4,248 results on '"M. Khalid"'
Search Results
52. Recent progress of magnetic nanoparticles in biomedical applications: A review
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Muzahidul I. Anik, M. Khalid Hossain, Imran Hossain, A. M. U. B. Mahfuz, M. Tayebur Rahman, and Isteaque Ahmed
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clinical trial ,CRISPR‐Cas9 ,drug delivery ,lab‐on‐a‐chip ,magnetic bioseparation ,magnetic hyperthermia ,Materials of engineering and construction. Mechanics of materials ,TA401-492 - Abstract
Abstract Magnetic nanoparticles (MNPs) offer tremendous potentialities in biomedical applications for a long while. Since these materials' interactions in biological media largely rely on their crystal structures, sizes, and shapes, detailed studies on their synthesis mechanism for medicinal aspects are crucial. Despite many review reports that have already been published on MNPs, they mainly have focused either on their perspective in biomedical applications or their synthesis and characterization along with functionalization mechanisms as individual entities. For this reason, this review uncovers a comprehensive insight into the ongoing improvement of fabrication processes, surface functionalization of MNPs for biomedical applications together. Besides, various magnetic nanocomposite (MNCs) for smart drug delivery, recent hyperthermia treatment, lab‐on‐a‐chip, and magnetic bio‐separation, and some of the recent emerging imaging techniques using MNPs are discussed. A detailed analysis of toxicity, challenges, and recent progress of clinical trials of MNPs is sketched out to open numerous entryways for advanced research on MNPs for biomedical applications.
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- 2021
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53. Microbicidal actives with virucidal efficacy against SARS-CoV-2 and other beta- and alpha-coronaviruses and implications for future emerging coronaviruses and other enveloped viruses
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M. Khalid Ijaz, Raymond W. Nims, Sifang Steve Zhou, Kelly Whitehead, Vanita Srinivasan, Tanya Kapes, Semhar Fanuel, Jonathan H. Epstein, Peter Daszak, Joseph R. Rubino, and Julie McKinney
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Medicine ,Science - Abstract
Abstract Mitigating the risk of acquiring coronaviruses including SARS-CoV-2 requires awareness of the survival of virus on high-touch environmental surfaces (HITES) and skin, and frequent use of targeted microbicides with demonstrated efficacy. The data on stability of infectious SARS-CoV-2 on surfaces and in suspension have been put into perspective, as these inform the need for hygiene. We evaluated the efficacies of formulated microbicidal actives against alpha- and beta-coronaviruses, including SARS-CoV-2. The coronaviruses SARS-CoV, SARS-CoV-2, human coronavirus 229E, murine hepatitis virus-1, or MERS-CoV were deposited on prototypic HITES or spiked into liquid matrices along with organic soil loads. Alcohol-, quaternary ammonium compound-, hydrochloric acid-, organic acid-, p-chloro-m-xylenol-, and sodium hypochlorite-based microbicidal formulations were evaluated per ASTM International and EN standard methodologies. All evaluated formulated microbicides inactivated SARS-CoV-2 and other coronaviruses in suspension or on prototypic HITES. Virucidal efficacies (≥ 3 to ≥ 6 log10 reduction) were displayed within 30 s to 5 min. The virucidal efficacy of a variety of commercially available formulated microbicides against SARS-CoV-2 and other coronaviruses was confirmed. These microbicides should be useful for targeted surface and hand hygiene and disinfection of liquids, as part of infection prevention and control for SARS-CoV-2 and emerging mutational variants, and other emerging enveloped viruses.
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- 2021
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54. Quantum Fisher Information of Three-Level Atom under the Influence of the Stark Effect and Intrinsic Dechorence
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S. Jamal Anwar, M. Ramzan, and M. Khalid Khan
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quantum entanglement (QE) ,quantum fisher information (QFI) ,the Stark effect ,von Neumann entropy (VNE) ,Nuclear and particle physics. Atomic energy. Radioactivity ,QC770-798 - Abstract
We study the dynamical evolution of quantum Fisher information (QFI) and von Neumann entropy (VNE) for a three-level atomic system interacting with the single-mode coherent field in the presence of the Stark effect and intrinsic decoherence (ID) with and without atomic motion. The effect of the ID is significant on the VNE and QFI for a three-level atom in the absence of atomic motion. It is observed that in the case of a three-level atomic system in the presence of ID, the decay of QFI and VNE is rapid and significant but no prominent effect of the Stark effect is observed. Hence, for a three-level atom, the decay of quantum entanglement (QE) with respect to time is very fast and rapid in the absence of atomic motion with an increasing value of ID. Moreover, ID is not suitable to maintain the QE for three-level atomic systems in the absence of atomic motion. The Stark effect has no significant effect on the QE. In the case of three-level atoms, ID and the Stark do not affect the periodic nature of QFI and VNE with time evolution in the presence of atomic motion. The periodic response of QFI and VNE is observed under the effect of the Stark effect and ID in the presence of a motion of a three-level atom. The QE sudden death and birth is observed in the presence of atomic motion. Therefore, the ID with the Stark effect is suitable to sustain and maintain the QE in the presence of atomic motion for three-level atomic systems. These results show the strong dependence of QFI and VNE on the Stark effect and ID.
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- 2023
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55. The Influence of Social Presence on Students’ Satisfaction toward Online Course
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M. Khalid M. Nasir
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social presence ,course satisfaction ,online learning ,community of inquiry (coi) ,Special aspects of education ,LC8-6691 - Abstract
Students’ satisfaction plays a vital role in ensuring effective online learning. This study investigated the association between social presence and students’ satisfaction toward online discussions in Learning Management System (LMS) platform conducted at a private university in Malaysia. Both correlation and two-step hierarchical linear regression were performed to analyze the online survey data. The instruments used to measure the summated scores of social presence and satisfaction were Community of Inquiry (CoI) framework and satisfaction scale, respectively. The results revealed that the correlation between both variables was significantly positive. Students who declared relatively high level of satisfaction were more likely to report high level of interaction with their peers in online conversation and high level of social presence. Essentially, social presence seemed to contribute the most in predicting the level of course satisfaction amongst the students.
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- 2020
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56. Dynamic simulation of articulated soft robots
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Weicheng Huang, Xiaonan Huang, Carmel Majidi, and M. Khalid Jawed
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Science - Abstract
To advance the design of soft robots, novel computational frameworks that accurately model the dynamics of soft material systems are required. Here, the authors report a numerical framework for studying locomotion in limbed soft robots that is based on the discrete elastic rods algorithm.
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- 2020
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57. Euler’s Numerical Method on Fractional DSEK Model under ABC Derivative
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Fareeha Sami Khan, M. Khalid, Omar Bazighifan, and A. El-Mesady
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Electronic computers. Computer science ,QA75.5-76.95 - Abstract
In this paper, DSEK model with fractional derivatives of the Atangana-Baleanu Caputo (ABC) is proposed. This paper gives a brief overview of the ABC fractional derivative and its attributes. Fixed point theory has been used to establish the uniqueness and existence of solutions for the fractional DSEK model. According to this theory, we will define two operators based on Lipschitzian and prove that they are contraction mapping and relatively compact. Ulam-Hyers stability theorem is implemented to prove the fractional DSEK model’s stability in Banach space. Also, fractional Euler’s numerical method is derived for initial value problems with ABC fractional derivative and implemented on fractional DSEK model. The symmetric properties contribute to determining the appropriate method for finding the correct solution to fractional differential equations. The numerical solutions generated using fractional Euler’s method have been plotted for different values of α where α∈0,1 and different step sizes h. Result discussion will be given, describing the changes that occur due to the step size h.
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- 2022
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58. Content-Based Image Retrieval Using Gamma Distribution and Mixture Model
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Yaser Daanial Khan, M. Khalid Mahmood, Daud Ahmad, and Nasser M. Al-Zidi
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Mathematics ,QA1-939 - Abstract
Since the last decade, the complexity of multimedia data, specifically images, is emerging exponentially as millions of images are uploaded by users on daily basis. Searching for a relevant image from such a substantial amount of data is very hectic and resource-demanding. To cope with this issue, researchers are working on content-based image retrieval (CBIR) approaches. This article proposes an efficient and novel probabilistic technique as a solution for content-based image retrieval. The patterns formed by the glyph structure of an image are excavated to yield content representations. These representations are accumulatively used to form a distribution, whereas the characteristics of this distribution represent the semantic structure of the image. In the end, the mixture model for gamma distribution is applied and parameters are refined through maximum likelihood. Furthermore, a mechanism is devised to retrieve matching images having comparable distribution patterns. Experiments show not only that the proposed technique yields a comparable precision to other competitive techniques but it also demonstrates that it is sufficiently efficient with high performance compared as compared to the others and requires unsupervised training.
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- 2022
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59. A Paradigmatic Approach to Find Equal Sum Partitions of Zero-Divisors via Complete Graphs
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M. Haris Mateen, M. Khalid Mahmood, Daud Ahmad, Shahbaz Ali, and Shajib Ali
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Chemistry ,QD1-999 - Abstract
In computer science and mathematics, a partition of a set into two or more disjoint subsets with equal sums is a well-known NP-complete problem. This is a hard problem and referred to as the partition problem or number partitioning. In this paper, we solve a particular type of NP-complete problem on the set of all zero-divisors of Zn including zero, where Zn is the ring of residue classes of a positive integer n. In this regard, we introduce and investigate quadratic zero-divisor graph in which we build an edge between zero-divisors zi and zj if and only if zi2≡zj2 mod n,i≠j. This is denoted as G⏞2,n. We characterize these graphs in term of complete graphs for classes of integers 2α,pα,2αp,2pα and pq, where α is any positive integer and p,q are odd primes.
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- 2022
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60. A Computational Model for q-Bernstein Quasi-Minimal Bézier Surface
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Daud Ahmad, M. Khalid Mahmood, Qin Xin, Ferdous M. O. Tawfiq, Sadia Bashir, and Arsha Khalid
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Mathematics ,QA1-939 - Abstract
A computational model is presented to find the q-Bernstein quasi-minimal Bézier surfaces as the extremal of Dirichlet functional, and the Bézier surfaces are used quite frequently in the literature of computer science for computer graphics and the related disciplines. The recent work [1–5] on q-Bernstein–Bézier surfaces leads the way to the new generalizations of q-Bernstein polynomial Bézier surfaces for the related Plateau–Bézier problem. The q-Bernstein polynomial-based Plateau–Bézier problem is the minimal area surface amongst all the q-Bernstein polynomial-based Bézier surfaces, spanned by the prescribed boundary. Instead of usual area functional that depends on square root of its integrand, we choose the Dirichlet functional. Related Euler–Lagrange equation is a partial differential equation, for which solutions are known for a few special cases to obtain the corresponding minimal surface. Instead of solving the partial differential equation, we can find the optimal conditions for which the surface is the extremal of the Dirichlet functional. We workout the minimal Bézier surface based on the q-Bernstein polynomials as the extremal of Dirichlet functional by determining the vanishing condition for the gradient of the Dirichlet functional for prescribed boundary. The vanishing condition is reduced to a system of algebraic constraints, which can then be solved for unknown control points in terms of known boundary control points. The resulting Bézier surface is q-Bernstein–Bézier minimal surface.
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- 2022
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61. Book Review of Evaluating Online Teaching: Implementing Best Practices
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NorHafizah Azhar and M. Khalid M. Nasir
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Online learning ,Social Science ,Instructional Design ,Special aspects of education ,LC8-6691 - Abstract
Thomas J. Tobin, B. Jean Mandernach & Ann H. Taylor (2015). Evaluating online teaching: implementing best practices. Jossey-Bass. 301 pages. ISBN 978-1-118-91036-8.
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- 2021
62. Freelance Model with Atangana–Baleanu Caputo Fractional Derivative
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Fareeha Sami Khan, M. Khalid, Areej A. Al-moneef, Ali Hasan Ali, and Omar Bazighifan
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Atangana–Baleanu fractional derivative ,local stability ,differential equation ,uniqueness and existence ,fractional Euler’s method ,numerical method ,Mathematics ,QA1-939 - Abstract
As technology advances and the Internet makes our world a global village, it is important to understand the prospective career of freelancing. A novel symmetric fractional mathematical model is introduced in this study to describe the competitive market of freelancing and the significance of information in its acceptance. In this study, fixed point theory is applied to analyze the uniqueness and existence of the fractional freelance model. Its numerical solution is derived using the fractional Euler’s method, and each case has been presented graphically as well as tabular. Further, the results have been compared with the classic freelance model and real data to show the importance of this model.
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- 2022
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63. Soap, water, and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2): an ancient handwashing strategy for preventing dissemination of a novel virus
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M. Khalid Ijaz, Raymond W. Nims, Sarah de Szalay, and Joseph R. Rubino
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SARS-CoV-2 ,Hierarchy of susceptibility to inactivation ,Infection prevention and control ,Hand disinfection ,Hand sanitizers ,Anti-infective agents ,Medicine ,Biology (General) ,QH301-705.5 - Abstract
Public Health Agencies worldwide (World Health Organization, United States Centers for Disease Prevention & Control, Chinese Center for Disease Control and Prevention, European Centre for Disease Prevention and Control, etc.) are recommending hand washing with soap and water for preventing the dissemination of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections. In this review, we have discussed the mechanisms of decontamination by soap and water (involving both removal and inactivation), described the contribution of the various components of formulated soaps to performance as cleansers and to pathogen inactivation, explained why adherence to recommended contact times is critical, evaluated the possible contribution of water temperature to inactivation, discussed the advantages of antimicrobial soaps vs. basic soaps, discussed the differences between use of soap and water vs. alcohol-based hand sanitizers for hand decontamination, and evaluated the limitations and advantages of different methods of drying hands following washing. While the paper emphasizes data applicable to SARS-CoV-2, the topics discussed are germane to most emerging and re-emerging enveloped and non-enveloped viruses and many other pathogen types.
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- 2021
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64. Isolation and characterization of bacteria residing in the oral, gut, and fecal samples of different pheasant species
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M. Mushtaq, S. M. Bukhari, S. Ahmad, A. Khattak, M. B. Chattha, I. Mubeen, K. Ur Rehman, S. Andleeb, S. Hussain, A. Javid, A. Hussain, W. Ali, N. Khalid, G. Mustafa, F. Sughra, M. J. Iqbal, M. Khalid, M. M. Naeem, and M. Inayat
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pheasants ,biochemical characterization ,fecal microbiota ,prevalence ,CFU method ,diversity ,microbiota ,Science ,Biology (General) ,QH301-705.5 ,Zoology ,QL1-991 ,Botany ,QK1-989 - Abstract
Abstract There is a paucity of research conducted on microbial prevalence in pheasants. The microbiota of captive birds has zoonotic significance and must be characterize. Present study is therefore planned to assess the microbiota from oral, fecal and gut content of captive avian species. It will be helpful in characterization of harmful microbes. Different samples taken from oral, gut and feces of ring-necked pheasants (Phasianus colchicus), green pheasants (Phasianus versicolor), golden pheasant (Chrysolophus pictus) and silver pheasant (Lophura nycthemera). Samples were collected, diluted, and inoculated onto different agar plates (MacConkey, SS agar, MSA and nutrient agar) for cultivation of bacterial species. Colonies of E.coli, Staphylococcus spp. Brachyspira spp. and Campylobacter spp were observed based on colony morphology. Colony forming unit showed E. coli as frequently found bacteria in fecal, oral and gut contents of all the above pheasants. The overall significance difference was found among bacterial species of golden pheasants, green pheasant, ring-necked pheasant, and silver pheasants. It was concluded that E.coli is predominant isolated from heathy pheasants followed by Campylobacter, Staphylococcus and Brachyspira.
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- 2021
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65. The impact of cow dung augmentation on soil restoration and bio-accumulation of metals (Lead and Cadmium) in Pheretima posthuma (Annelida: Clitellata)
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M. Hussain, I. Liaqat, S. M. Bukhari, F. S. Khan, R. Adalat, M. Salman Shafique, S. M. Azam, A. Ali, M. Khalid, Z. Shahid, M. Javed Iqbal, Slahuddin, and A. Ehsan
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cow dung ,bio-assimilation ,heavy metals ,soil reclamation ,Pheretima posthuma ,Science ,Biology (General) ,QH301-705.5 ,Zoology ,QL1-991 ,Botany ,QK1-989 - Abstract
Abstract To investigate the role of cow dung in soil reclamation and bio assimilation along with bio accumulation of heavy metals in earthworm (P. posthuma) (N=900) earthworms were used and treatment groups of CD-soil mixture of different proportion of cow dung were designed. Nonlethal doses of lead acetate and cadmium chloride were added in treatment groups. Mature P. posthuma were released in each experimental pot maintaining the favorable conditions. The pH, carbon, nitrogen, phosphorus, exchangeable cations, and heavy metal level of each mixture was evaluated. The results indicated that bio-assimilation of Pb and Cd by P. posthuma were significantly (P ˂ 0.01) higher in different soil-CD treatments compared to control. Highest bio-assimilation of both metals was observed in T1 of both groups (Pb = 563.8 mg/kg and Cd = 42.95 mg/kg). The contents of both metals were significantly (P ˂ 0.05) lowered in casting. The nutrient concentration in the final castings of all soil-CD treatments were also equally transformed from less or insoluble to more soluble and available for plants, except for carbon level which increased with CD proportion. It is concluded that cow dung as organic matter has a positive effect on soil reclamation and bio-assimilation of metals by P. posthuma.
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- 2021
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66. Thalassemia, a human blood disorder
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F. Shafique, S. Ali, T. Almansouri, F. Van Eeden, N. Shafi, M. Khalid, S. Khawaja, S. Andleeb, and M. ul Hassan
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thalassemias ,beta globin genes ,hemoglobinopathies ,Science ,Biology (General) ,QH301-705.5 ,Zoology ,QL1-991 ,Botany ,QK1-989 - Abstract
Abstract A group of inherited blood defects is known as Thalassemia is among the world’s most prevalent hemoglobinopathies. Thalassemias are of two types such as Alpha and Beta Thalassemia. The cause of these defects is gene mutations leading to low levels and/or malfunctioning α and β globin proteins, respectively. In some cases, one of these proteins may be completely absent. α and β globin chains form a globin fold or pocket for heme (Fe++) attachment to carry oxygen. Genes for alpha and beta-globin proteins are present in the form of a cluster on chromosome 16 and 11, respectively. Different globin genes are used at different stages in the life course. During embryonic and fetal developmental stages, γ globin proteins partner with α globin and are later replaced by β globin protein. Globin chain imbalances result in hemolysis and impede erythropoiesis. Individuals showing mild symptoms include carriers of alpha thalassemia or the people bearing alpha or beta-thalassemia trait. Alpha thalassemia causes conditions like hemolytic anemia or fatal hydrops fetalis depending upon the severity of the disease. Beta thalassemia major results in hemolytic anemia, growth retardation, and skeletal aberrations in early childhood. Children affected by this disorder need regular blood transfusions throughout their lives. Patients that depend on blood transfusion usually develop iron overload that causes other complications in the body systems like renal or hepatic impairment therefore, thalassemias are now categorized as a syndrome. The only cure for Thalassemias would be a bone marrow transplant, or gene therapy with currently no significant success rate. A thorough understanding of the molecular basis of this syndrome may provide novel insights and ideas for its treatment, as scientists have still been unable to find a permanent cure for this deadly disease after more than 87 years since it is first described in 1925.
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- 2021
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67. Comparison of the Efficacy of Disinfectant Pre-impregnated Wipes for Decontaminating Stainless Steel Carriers Experimentally Inoculated With Ebola Virus and Vesicular Stomatitis Virus
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Todd A. Cutts, Samantha B. Kasloff, Jay Krishnan, Raymond W. Nims, Steven S. Theriault, Joseph R. Rubino, and M. Khalid Ijaz
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ASTM E2967-15 ,disinfectant pre-impregnated wipes ,Ebola virus Makona variant ,viral removal/inactivation ,vesicular stomatitis virus ,wiperator ,Public aspects of medicine ,RA1-1270 - Abstract
The authors evaluated four disinfectant pre-impregnated wipes (DPW) for efficacy against Ebola virus Makona variant (EBOV) and vesicular stomatitis virus (VSV), Indiana serotype. Steel carriers were inoculated with the infectious virus and then were wiped with DPW in the Wiperator instrument per ASTM E2967-15. Following the use of J-Cloth impregnated with medium (negative control wipes) or the use of activated hydrogen peroxide (AHP)-, ethanol-, sodium hypochlorite (NaOCl)-, or single or dual quaternary ammonium compound (QAC)-based DPW, virus recovery from the carriers was assayed by titration assay and by two passages on Vero E6 cells in 6-well plates. The Wiperator also enabled the measurement of potential transfer of the virus from the inoculated carrier to a secondary carrier by the DPW or control wipes. The J-Cloth wipes wetted with medium alone (no microbicidal active) removed 1.9–3.5 log10 of virus from inoculated carriers but transferred ~4 log10 of the wiped virus to secondary carriers. DPW containing AHP, ethanol, NaOCl, or single or dual QAC as active microbicidal ingredients removed/inactivated ~6 log10 of the virus, with minimal EBOV or no VSV virus transfer to a secondary surface observed. In Ebola virus outbreaks, a DPW with demonstrated virucidal efficacy, used as directed, may help to mitigate the unintended spread of the infectious virus while performing surface cleaning.
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- 2021
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68. A Review of Applications, Prospects, and Challenges of Proton-Conducting Zirconates in Electrochemical Hydrogen Devices
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M. Khalid Hossain, S. M. Kamrul Hasan, M. Imran Hossain, Ranjit C. Das, H. Bencherif, M. H. K. Rubel, Md. Ferdous Rahman, Tanvir Emrose, and Kenichi Hashizume
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perovskite oxide ,proton-conducting oxide ,zirconate ,electrochemical device ,tritium monitoring ,tritium recovery ,Chemistry ,QD1-999 - Abstract
In the future, when fossil fuels are exhausted, alternative energy sources will be essential for everyday needs. Hydrogen-based energy can play a vital role in this aspect. This energy is green, clean, and renewable. Electrochemical hydrogen devices have been used extensively in nuclear power plants to manage hydrogen-based renewable fuel. Doped zirconate materials are commonly used as an electrolyte in these electrochemical devices. These materials have excellent physical stability and high proton transport numbers, which make them suitable for multiple applications. Doping enhances the physical and electronic properties of zirconate materials and makes them ideal for practical applications. This review highlights the applications of zirconate-based proton-conducting materials in electrochemical cells, particularly in tritium monitors, tritium recovery, hydrogen sensors, and hydrogen pump systems. The central section of this review summarizes recent investigations and provides a comprehensive insight into the various doping schemes, experimental setup, instrumentation, optimum operating conditions, morphology, composition, and performance of zirconate electrolyte materials. In addition, different challenges that are hindering zirconate materials from achieving their full potential in electrochemical hydrogen devices are discussed. Finally, this paper lays out a few pathways for aspirants who wish to undertake research in this field.
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- 2022
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69. Ecological impacts of climate change on the snow leopard (Panthera unica) in South Asia
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F. A. Kazmi, F. Shafique, M. U. Hassan, S. Khalid, N. Ali, N. Akbar, K. Batool, M. Khalid, and S. Khawaja
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snow leopard ,South Asia ,Himalaya ,Karakorum ,climate change ,habitat loss ,Science ,Biology (General) ,QH301-705.5 ,Zoology ,QL1-991 ,Botany ,QK1-989 - Abstract
Abstract Snow leopard (Panthera unica) is a felid which lives in the highly rugged areas of alpine regions in different mountain ranges of South and Central Asia. This solitary animal needs large spaces for its ranges but due to climate change and relatively faster rate of global warming in South Asian mountain ranges, its habitat is going to shrink and fragment by tree-line shifts and change in hydrology of the area. Vegetative modification of montane flora and competition with domestic goats will create its prey’s population to decline along with a chance of a direct conflict and competition with the common leopard. Common leopard being more adaptable, grouped, and larger in size can be a significant stressor for a smaller and solitary snow leopard. Habitat would shrink, and snow leopard can possibly move upslope or northward to central Asian ranges and their predicted migratory patterns are unknown.
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- 2021
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70. Smart nanocarrier-based drug delivery systems for cancer therapy and toxicity studies: A review
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Sarwar Hossen, M. Khalid Hossain, M.K. Basher, M.N.H. Mia, M.T. Rahman, and M. Jalal Uddin
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Medicine (General) ,R5-920 ,Science (General) ,Q1-390 - Abstract
Nonspecific distribution and uncontrollable release of drugs in conventional drug delivery systems (CDDSs) have led to the development of smart nanocarrier-based drug delivery systems, which are also known as Smart Drug Delivery Systems (SDDSs). SDDSs can deliver drugs to the target sites with reduced dosage frequency and in a spatially controlled manner to mitigate the side effects experienced in CDDSs. Chemotherapy is widely used to treat cancer, which is the second leading cause of death worldwide. Site-specific drug delivery led to a keen interest in the SDDSs as an alternative to chemotherapy. Smart nanocarriers, nanoparticles used to carry drugs, are at the focus of SDDSs. A smart drug delivery system consists of smart nanocarriers, targeting mechanisms, and stimulus techniques. This review highlights the recent development of SDDSs for a number of smart nanocarriers, including liposomes, micelles, dendrimers, meso-porous silica nanoparticles, gold nanoparticles, super paramagnetic iron-oxide nanoparticles, carbon nanotubes, and quantum dots. The nanocarriers are described in terms of their structures, classification, synthesis and degree of smartness. Even though SDDSs feature a number of advantages over chemotherapy, there are major concerns about the toxicity of smart nanocarriers; therefore, a substantial study on the toxicity and biocompatibility of the nanocarriers has been reported. Finally, the challenges and future research scope in the field of SDDSs are also presented. It is expected that this review will be widely useful for those who have been seeking new research directions in this field and for those who are about to start their studies in smart nanocarrier-based drug delivery. Keywords: Smart drug delivery, Smart nanocarrier, Nanocarrier functionalization, Toxicity of nanocarrier, Cancer cell targeting, Drug release stimulus
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- 2019
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71. Emerging SARS-CoV-2 Mutational Variants of Concern Should Not Vary in Susceptibility to Microbicidal Actives
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M. Khalid Ijaz, Raymond W. Nims, and Julie McKinney
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coronavirus ,COVID-19 ,decontamination of surfaces and hands ,Beta variant ,Delta variant ,formulated microbicidal active ,Science - Abstract
The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is evolving, with emergence of mutational variants due to the error-prone replication process of RNA viruses, in general. More recently, the Delta and Omicron variants (including sub-variants BA.1–5) predominate globally, and a Delta–Omicron recombinant termed Deltacron has emerged. The emergence of variants of concern (VOC) demonstrating immune evasion and potentially greater transmissibility and virulence naturally raises concern in both the infection control communities and the public at large, as to the continued suitability of interventions intended to mitigate the risk of viral dissemination and acquisition of the associated disease COVID-19. We evaluated the virucidal efficacy of targeted surface hygiene products (an ethanol/quaternary ammonium compound (QAC)-containing disinfectant spray, a QAC disinfectant wipe, a lactic acid disinfectant wipe, and a citric acid disinfectant wipe) through both theoretical arguments and empirical testing using international standard methodologies (ASTM E1053-20 hard surface test and EN14476:2013+A2:2019 suspension test) in the presence of soil loads simulating patients’ bodily secretions/excretions containing shed virus. The results demonstrate, as expected, complete infectious viral inactivation (≥3.0 to ≥4.7 log10 reduction in infectious virus titer after as little as 15 s contact time at room temperature) by these surface hygiene agents of the original SARS-CoV-2 isolate and its Beta and Delta VOC. Through appropriate practices of targeted surface hygiene, it is expected that irrespective of the SARS-CoV-2 VOC encountered as the current pandemic unfolds (and, for that matter, any emerging and/or re-emerging enveloped virus), the chain of infection from virus-contaminated fomites to the hand and mucous membranes of a susceptible person may be disrupted.
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- 2022
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72. Impact of ionizing radiation doses on nanocrystalline TiO2 layer in DSSC’s photoanode film
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M. Khalid Hossain, M.T. Rahman, M.K. Basher, M.J. Afzal, and M.S. Bashar
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Physics ,QC1-999 - Abstract
In dye-sensitized solar cell (DSSC) properties of nanocrystalline oxide layer of photoanode may changes when exposed to ionization radiation environment which may leads to change the cell performance. In this study, 10 µm thick TiO2 (Degussa-P25) was deposited as a photoanode film on microscopic glass slide with the doctor-blade coating. The deposited film was subjected to different gamma (γ) radiation doses (0–20 kGy) to study the effect of ionizing radiation on morphological, structural, optical and compositional characteristics of the film. At 10 kGy dose, dislocation density (DD), strain, crystallites per unit surface area (CPSA), specific surface area (SSA) of anatase phase (1 0 1) of the film were decreased abruptly, conversely, crystal size and morphology index (MI) were increased at the same radiation dose slowly. UV-Vis-NIR spectroscopy results showed that in irradiated photoanode film the light transmittance and absorption depth were decreased, whereas, absorption and absorption coefficient were increased beyond the visible wavelength. The optical band gap of the irradiated film was increased by 12.5% when the gamma radiation dose increased from 0 kGy to 20 kGy. Thus, the irradiation induced changes in physio-chemical properties of nanocrystalline photoanode film may affect the DSSC cell performance. Keywords: Effect of ionizing radiation, Structural properties, Optical properties, DSSC photoanode film, Nanocrystalline TiO2, Dye-sensitized solar cell
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- 2018
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73. On Symmetry of Complete Graphs over Quadratic and Cubic Residues
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M. Haris Mateen, M. Khalid Mahmood, Shahbaz Ali, and M. D. Ashraful Alam
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Chemistry ,QD1-999 - Abstract
In this study, we investigate two graphs, one of which has units of a ring Zn as vertices (or nodes) and an edge will be built between two vertices u and v if and only if u3≡v3mod n. This graph will be termed as cubic residue graph. While the other is called Gaussian quadratic residue graph whose vertices are the elements of a Gaussian ring Zni of the form α=a+ib,β=c+i d, where a,b,c,d are the units of Zn. Two vertices α and β are adjacent to each other if and only if α2≡β2mod n. In this piece of work, we characterize cubic and Gaussian quadratic residue graphs for each positive integer n in terms of complete graphs.
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- 2021
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74. Variationally Improved Bézier Surfaces with Shifted Knots
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Daud Ahmad, Kanwal Hassan, M. Khalid Mahmood, Javaid Ali, Ilyas Khan, and M. Fayz-Al-Asad
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Physics ,QC1-999 - Abstract
The Plateau-Bézier problem with shifted knots is to find the surface of minimal area amongst all the Bézier surfaces with shifted knots spanned by the admitted boundary. Instead of variational minimization of usual area functional, the quasi-minimal Bézier surface with shifted knots is obtained as the solution of variational minimization of Dirichlet functional that turns up as the sum of two integrals and the vanishing condition gives us the system of linear algebraic constraints on the control points. The coefficients of these control points bear symmetry for the pair of summation indices as well as for the pair of free indices. These linear constraints are then solved for unknown interior control points in terms of given boundary control points to get quasi-minimal Bézier surface with shifted knots. The functional gradient of the surface gives possible candidate functions as the minimizers of the aforementioned Dirichlet functional; when solved for unknown interior control points, it results in a surface of minimal area called quasi-minimal Bézier surface. In particular, it is implemented on a biquadratic Bézier surface by expressing the unknown control point P11 as the linear combination of the known control points in this case. This can be implemented to Bézier surfaces with shifted knots of higher degree, as well if desired.
- Published
- 2021
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75. Gold and platinum functionalized arsenene for the detection of CH3Cl and CH3Br: first-principles insights
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Mushtaq, Muhammad, Chang, Zheng, Khan, Muhammad Abdul Rauf, Leilei, Zhang, Ayesh, Ahmad I., El-Muraikhi, Maitha D., Algethami, Norah, Rahman, Md. Ferdous, and Hossain, M. Khalid
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- 2024
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76. Eco-friendly Sustainable Dyeing of Lycra Viscose Fabric with Allium sativum Using Natural and Metal Mordants
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Toki, Gazi Farhan Ishraque, Muntasin, Md., Roy, Sourav Kantee, Mia, Rony, Ahmed, Taosif, Alave, Rezaul Karim Khan, Ghosh, Sumonta, Almarhoon, Zainab M., and Hossain, M. Khalid
- Published
- 2024
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77. Numerical analysis of silicon nitride and perovskite nanomaterial assisted SPR biosensor for dengue cell detection
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Singh, Nikhil Pratap, Mishra, Adarsh Chandra, Yadav, Sapana, Lohia, Pooja, Dwivedi, D. K., Tighezza, Ammar M., and Hossain, M. Khalid
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- 2024
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78. Deciphering the mechanisms and contributions of ceramic-based materials in hydrogen storage applications: a contemporary outlook
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Rahman, M. Atikur, Taher, Abu, Mia, Rana, Chowdhury, Faisal I., Khandaker, Mayeen Uddin, Osman, Hamid, Hossain, M. Khalid, Al-Sehemi, Abdullah G., Ghann, W., Alim, Mohammad A., and Uddin, Jamal
- Published
- 2024
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79. High-efficiency silicon solar cells designed on experimentally achieved nano-engineered low-reflective silicon surface
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Zumahi, S. M. Amir-Al, Basher, M. Khairul, Arobi, Nourin, Rahman, M. Momtazur, Tawfeek, Ahmed M., Akand, M. A. Rafiq, Rahman, M. Mahbubur, Nur-E-Alam, M., and Hossain, M. Khalid
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- 2024
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80. Lead-free Ge-based perovskite solar cell incorporating TiO2 and Cu2O charge transport layers harnessing over 25% efficiency
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Uddin, M. Shihab, Al Mashud, Md. Abdullah, Toki, G. F. Ishraque, Pandey, Rahul, Zulfiqar, Muhammad, Saidani, Okba, Chandran, Karnan, Ouladsmane, Mohamed, and Hossain, M. Khalid
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- 2024
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81. Attaining above 30% efficiency of PbS-based colloidal quantum dot solar cell using MoO3 and SnO2 as charge transport layers: a numerical approach
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Singh, Jyoti, Agarwal, Surbhi, Srivastava, Vaibhava, Sadanand, Maurya, Hossain, M. Khalid, Pandey, Rahul, Madan, Jaya, Lohia, Pooja, Dwivedi, D. K., and Ouladsmane, Mohamed
- Published
- 2024
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82. Automatic discovery of clinically interpretable imaging biomarkers for Mycobacterium tuberculosis supersusceptibility using deep learning
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Thomas E. Tavolara, M. Khalid Khan Niazi, Melanie Ginese, Cesar Piedra-Mora, Daniel M. Gatti, Gillian Beamer, and Metin N. Gurcan
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Granuloma ,Lung ,Diversity outbred mice ,Multiple instance learning ,Biomarkers ,Tuberculosis ,Medicine ,Medicine (General) ,R5-920 - Abstract
Background: Identifying which individuals will develop tuberculosis (TB) remains an unresolved problem due to few animal models and computational approaches that effectively address its heterogeneity. To meet these shortcomings, we show that Diversity Outbred (DO) mice reflect human-like genetic diversity and develop human-like lung granulomas when infected with Mycobacterium tuberculosis (M.tb) . Methods: Following M.tb infection, a “supersusceptible” phenotype develops in approximately one-third of DO mice characterized by rapid morbidity and mortality within 8 weeks. These supersusceptible DO mice develop lung granulomas patterns akin to humans. This led us to utilize deep learning to identify supersusceptibility from hematoxylin & eosin (H&E) lung tissue sections utilizing only clinical outcomes (supersusceptible or not-supersusceptible) as labels. Findings: The proposed machine learning model diagnosed supersusceptibility with high accuracy (91.50 ± 4.68%) compared to two expert pathologists using H&E stained lung sections (94.95% and 94.58%). Two non-experts used the imaging biomarker to diagnose supersusceptibility with high accuracy (88.25% and 87.95%) and agreement (96.00%). A board-certified veterinary pathologist (GB) examined the imaging biomarker and determined the model was making diagnostic decisions using a form of granuloma necrosis (karyorrhectic and pyknotic nuclear debris). This was corroborated by one other board-certified veterinary pathologist. Finally, the imaging biomarker was quantified, providing a novel means to convert visual patterns within granulomas to data suitable for statistical analyses. Implications: Overall, our results have translatable implication to improve our understanding of TB and also to the broader field of computational pathology in which clinical outcomes alone can drive automatic identification of interpretable imaging biomarkers, knowledge discovery, and validation of existing clinical biomarkers. Funding: National Institutes of Health and American Lung Association.
- Published
- 2020
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83. Virucidal Action Mechanism of Alcohol and Divalent Cations Against Human Adenovirus
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Natalia Martín-González, Leonam Vieira Gonçalves, Gabriela N. Condezo, Carmen San Martín, María Rubiano, Ian Fallis, Joseph R. Rubino, M. Khalid Ijaz, Jean-Yves Maillard, and Pedro J. De Pablo
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virus damage ,biocides ,virus mechanics ,AFM ,adenovirus ,Biology (General) ,QH301-705.5 - Abstract
Hygiene and disinfection practices play an important role at preventing spread of viral infections in household, industrial and clinical settings. Although formulations based on >70% ethanol are virucidal, there is a currently a need to reformulate products with much lower alcohol concentrations. It has been reported that zinc can increase the virucidal activity of alcohols, although the reasons for such potentiation is unclear. One approach in developing virucidal formulations is to understand the mechanisms of action of active ingredients and formulation excipients. Here, we investigated the virucidal activity of alcohol (40% w/v) and zinc sulfate (0.1% w/v) combinations and their impact on a human adenovirus (HAdV) using, nucleic acid integrity assays, atomic force microscopy (AFM) and transmission electron microscopy (TEM). We observed no difference in virucidal activity (5 log10 reduction in 60 min) against between an ethanol only based formulation and a formulation combining ethanol and zinc salt. Furthermore, TEM imaging showed that the ethanol only formulation produced gross capsid damage, whilst zinc-based formulation or formulation combining both ethanol and zinc did not affect HAdV DNA. Unexpectedly, the addition of nickel salt (5 mM NiCl2) to the ethanol-zinc formulation contributed to a weakening of the capsid and alteration of the capsid mechanics exemplified by AFM imaging, together with structural capsid damage. The addition of zinc sulfate to the ethanol formulation did not add the formulation efficacy, but the unexpected mechanistic synergy between NiCl2 and the ethanol formulation opens an interesting perspective for the possible potentiation of an alcohol-based formulation. Furthermore, we show that AFM can be an important tool for understanding the mechanistic impact of virucidal formulation.
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- 2020
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84. Evaluation of the hydrogen solubility and diffusivity in proton-conducting oxides by converting the PSL values of a tritium imaging plate
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M. Khalid Hossain, Kenichi Hashizume, and Yuji Hatano
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Barium zirconate (BaZrO3) ,Calcium zirconate (CaZrO3) ,Photostimulated luminescence (PSL) ,Tritium imaging plate (TIP) ,Hydrogen solubility and diffusivity ,Fusion reactors materials ,Nuclear engineering. Atomic power ,TK9001-9401 - Abstract
Proton-conducting oxides have potential applications in hydrogen sensors, hydrogen pumps, and other electrochemical devices including the tritium purification and recovery systems of nuclear fusion reactors. Although the distribution of hydrogen (H) in such oxide materials is an important aspect, its precise measurement is difficult. In the present study, the hydrogen solubility and diffusivity behavior of BaZr0.9Y0.1O2.95 (BZY), BaZr0.955Y0.03Co0.015O2.97 (BZYC), and CaZr0.9In0.1O2.95 (CZI) were studied using tritiated heavy water vapor i.e., DTO (~2 kPa, tritium (T) = 0.1%) by converting the photostimulated luminescence (PSL) values of the imaging plate (IP). The samples were exposed to DTO vapor at 673 K for 2 h or at 873 K for 1 h. The disc-shaped oxide specimens (diameter ~ 7.5 mm; thickness ~ 2.3 mm; theoretical density (TD) greater than 98%) were prepared by conventional powder metallurgy. The IP images of the specimen surfaces of all the three materials T-exposed revealed that BZY showed the most uniform T distribution with the highest tritium activity. The cross-sectional T concentration profiles of the cut specimens showed that T diffused deeper into BZY and BZYC than into CZI. The hydrogen solubility and diffusivity in the CZI specimen were lower than that in the BZY and BZYC specimens. This suggested that barium zirconates were more favorable proton conductors than calcium zirconates.
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- 2020
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85. Combating SARS-CoV-2: leveraging microbicidal experiences with other emerging/re-emerging viruses
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M. Khalid Ijaz, Syed A. Sattar, Joseph R. Rubino, Raymond W. Nims, and Charles P. Gerba
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Ebola virus ,Enterovirus D68 ,Hantaan virus ,Lassa virus ,Microbicides ,MERS-CoV ,Medicine ,Biology (General) ,QH301-705.5 - Abstract
The emergence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in Wuhan City, China, late in December 2019 is an example of an emerging zoonotic virus that threatens public health and international travel and commerce. When such a virus emerges, there is often insufficient specific information available on mechanisms of virus dissemination from animal-to-human or from person-to-person, on the level or route of infection transmissibility or of viral release in body secretions/excretions, and on the survival of virus in aerosols or on surfaces. The effectiveness of available virucidal agents and hygiene practices as interventions for disrupting the spread of infection and the associated diseases may not be clear for the emerging virus. In the present review, we suggest that approaches for infection prevention and control (IPAC) for SARS-CoV-2 and future emerging/re-emerging viruses can be invoked based on pre-existing data on microbicidal and hygiene effectiveness for related and unrelated enveloped viruses.
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- 2020
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86. Assessing the Contributions of Inactivation, Removal, and Transfer of Ebola Virus and Vesicular Stomatitis Virus by Disinfectant Pre-soaked Wipes
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Todd A. Cutts, Catherine Robertson, Steven S. Theriault, Raymond W. Nims, Samantha B. Kasloff, Joseph R. Rubino, and M. Khalid Ijaz
- Subjects
ASTM E2967-15 ,Disinfectant pre-soaked wipes ,Ebola virus—Makona strain ,inactivation ,removal ,transfer ,Public aspects of medicine ,RA1-1270 - Abstract
Disinfectant pre-soaked wipes (DPW) containing activated hydrogen peroxide (AHP) or quaternary ammonium compounds (QAC) were tested using ASTM E2967-15 to determine removal, transfer, and inactivation of Ebola virus Makona variant (EBOV/Mak) and vesicular stomatitis virus (VSV) from contaminated stainless steel prototypic environmental surfaces. The infectious virus-contaminated carriers were subjected to wiping in the Wiperator per the standard. Following the use of negative control (J-Cloth)-, AHP-, or QAC-based wipes, recovery of residual infectious virus was assayed. In the case of the J-Cloth wipes (negative control), although removal of virus from inoculated carriers was extensive i.e., ~99% (1.9–3.5 log10) transfer of virus by these wipes to a secondary surface amounted to ≤ 2% (~3.8 log10) of the initial virus load. In the case of each DPW, >6 log10 removal/inactivation of virus was observed, with limited (EBOV/Mak) or no (VSV) virus transfer observed. The efficacy of wipes for decontaminating high-touch environmental surfaces spiked with EBOV/Mak or VSV is discussed. In summary, removal of EBOV/Mak and VSV using wipes was extensive in this study. In the absence of a sufficient concentration and contact time of an appropriate microbicidal active in DPW (such as the AHP- and QAC-based DPW tested), transfer of a low, albeit significant (from an infectious unit/infectious dose perspective), quantity of infectious virus from the inoculated surface to a secondary surface was observed. In the case of Ebola virus, it is essential that a DPW with an appropriate microbicidal active, following the appropriate contact time, be used to prevent unintended transfer of infectious virus to a clean secondary surface (as observed in negative control /J-Cloth). Otherwise, there exists the possibility of dissemination of Ebola virus and the associated risk of transmission of Ebola virus disease.
- Published
- 2020
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87. Study and investigation of phosphorus doping time on emitter region for contact resistance optimization of monocrystalline silicon solar cell
- Author
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M.K. Basher, M. Khalid Hossain, R. Afaz, S. Tayyaba, M.A.R. Akand, M.T. Rahman, and N.M. Eman
- Subjects
Physics ,QC1-999 - Abstract
In this paper, contact resistance of monocrystalline silicon solar cells was optimized by the variation of phosphorus doping time on emitter region. Wet-chemical texturization was performed to form pyramidal structure on silicon wafer surface. The surface morphology of the textured wafers was studied by field emission scanning electron microscope (FESEM) and surface reflection measurement (SRM). The textured wafers were doped by varying phosphorus doping time using constant flow rate of phosphorus oxychloride (POCl3) in a high-temperature diffusion furnace. The phosphorus doped silicon wafers were metalized by screen printer using silver and aluminum paste in the front and back surface of the wafers respectively. To form ohmic contacts between silver/aluminum layer and the silicon wafer, rapid thermal annealing (RTA) was performed on the screen-printed solar cells. The contact resistance of screen-printed solar cells was measured using transmission line method (TLM). 25 minutes doped sample showed minimum front and back contact resistances, which could potentially be useful for efficient monocrystalline silicon solar cells fabrication. Keywords: silicon solar cell, phosphorous diffusion, doping time, contact resistance, transmission line method, surface reflection measurement
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- 2018
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88. CHOLINE CHLORIDE:UREA-BASED DEEP EUTECTIC SOLVENT AS ADDITIVE TO PROTON CONDUCTING CHITOSAN FILMS
- Author
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W. Y. WONG, C. Y. WONG, W. RASHMI, and M. KHALID
- Subjects
Chitosan membrane ,Morphology ,Plasticiser ,Proton conductivity ,Engineering (General). Civil engineering (General) ,TA1-2040 ,Technology (General) ,T1-995 - Abstract
Chitosan (CS) film has been regarded as one of the bioresources that shows its ability to conduct proton upon modification. Nonetheless, CS film in nature is brittle and shows extremely high swelling degree towards water, leading to the impractical applications for fuel cell membranes and batteries. Formation of natural polymeric film requires plasticiser to crosslink natural polymers in improving the mechanical strength. Here, we investigate the potential of choline chloride (ChCl) and urea based deep eutectic solvent (DES) as additive in CS film with the aim to improve the mechanical property of the film. In this study, ChCl:urea- based DES was mixed with pure CS solution at different volume ratio and casted into a film. The film will be investigated on the functional groups, water uptake, ionic conductivity, proton exchange capacity and its morphology. Based on the SEM morphology result, it was found that addition of DES improves the homogeneity of the membrane film mainly attributed to the presence of strong bonds between the CS monosaccharides. Besides that, it also contributed towards better plasticising effect of the film that improves the flexibility of the membrane. The addition of DES has further improved the ionic conductivity of CS film from 2.98×10-3 to 1.23×10-2 S/cm; while drastically reduced the water uptake from 698.89 % to 180.67 %.
- Published
- 2018
89. Fabrication and comparative study of magnetic Fe and α-Fe2O3 nanoparticles dispersed hybrid polymer (PVA + Chitosan) novel nanocomposite film
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Md. Asadul Hoque, M.R. Ahmed, G.T. Rahman, M.T. Rahman, M.A. Islam, Mubarak A. Khan, and M. Khalid Hossain
- Subjects
Physics ,QC1-999 - Abstract
Incorporation of nanoparticles into polymer matrix allows the development of new features that differs from the pure materials. In this research, magnetic nanoparticles reinforced organic biodegradable polymer matrix based biocompatible nanocomposite films were fabricated. This work covered, synthesis of Iron (Fe) and Iron oxide (α-Fe2O3) nanoparticles by chemical reduction and sol-gel method respectively, fabrication of Fe/Polyvinyl alcohol (PVA)/Chitosan and α-Fe2O3/PVA/Chitosan nanocomposites by solvent casting method, and evaluation and comparison of their mechanical properties to find the superior biocompatible nanocomposite. The X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDX) analysis confirmed the size, structure, morphology and formation of Fe and α-Fe2O3 nanoparticles. Magnetic study showed that, synthesized α-Fe2O3 nanoparticle possess better magnetic properties than the Fe nanoparticle. The Fourier-transform infrared spectroscopy (FTIR) spectra confirmed the successful interaction of Fe and α-Fe2O3 nanoparticles with the polymer matrix. The Iron oxide dispersed (16.67 wt%) nanocomposite α-Fe2O3/PVA/Chitosan showed highest tensile strength and elastic modulus that is respectively 45% and 40% higher than the PVA polymer alone. This novel nanocomposite may potentially be useful in various biomedical applications. Keywords: Magnetic nanoparticles, Sol-gel and chemical reduction method, Biodegradable polymer, Biocompatible nanocomposite, Mechanical properties, Biomedical applications
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- 2018
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90. Numerical prediction of shock/boundary-layer interactions at high Mach numbers using a modified Spalart–Allmaras model
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Amjad Ali Pasha, K. A. Juhany, and M. Khalid
- Subjects
High speed flows ,shock wave ,turbulent boundary layer ,shock unsteadiness ,separation bubble ,turbulence modeling ,Engineering (General). Civil engineering (General) ,TA1-2040 - Abstract
The Reynolds-averaged Navier–Stokes equations with one-equation turbulence models are used to simulate the flow field past a cone–flare geometry in the Mach number range from 5 to 8 with emphasis on the interaction region of the flare shock with the upstream boundary layer. A model based on the physics of shock unsteadiness is used to correct the standard Spalart–Allmaras turbulence model to improve the prediction of the extent of the separation bubble arising from the shock/turbulent boundary-layer interaction and its accompanying peak pressure and aerothermal loads on the surface. The computed results are validated against the experimental data. The limitations of the shock-unsteadiness model and the extent of the improvement in predicting the heat flux are discussed.
- Published
- 2018
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91. Time and pressure dependent deformation of microcontact printed channels fabricated using self-assembled monolayers of alkanethiol on gold
- Author
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M. Jalal Uddin, M. Khalid Hossain, Wayesh Qarony, Mohammad I. Hossain, M.N.H. Mia, and S. Hossen
- Subjects
Microcontact printing (μCP) ,PDMS ,Self-assembled monolayers (SAMs) ,Polyethylene terephthalate (PET) ,Au ,Alkanethiol ,Materials of engineering and construction. Mechanics of materials ,TA401-492 - Abstract
In this work, the replication-based microcontact printing method has been presented to study the deformation effect of different printing times and printing pressures on the microcontact printed structures. Cost-effective microcontact printing channels of self-assembled monolayers of alkanethiol have been prepared on gold surface. The alkanethiol inking the polydimethylsiloxanes stamp effectively forms the self-assembled monolayers on the noble gold surface that protects the metal against etchant solution and thereby forms channel-like structures. To address the deformation issue, variations in the printing time in the range of 30 s–60 min and the printing pressure ranging from 840 to 4200 Pa have been studied. The estimation of differing the channel width and channel space with varying printing time and pressure shows the best resolution structures printed under minimal printing time at atmospheric pressure.
- Published
- 2017
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- View/download PDF
92. Influence of Mg content on tailoring optical bandgap of Mg-doped ZnO thin film prepared by sol-gel method
- Author
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M.N.H. Mia, M.F. Pervez, M. Khalid Hossain, M. Reefaz Rahman, M. Jalal Uddin, M.A. Al Mashud, H.K. Ghosh, and Mahbubul Hoq
- Subjects
Physics ,QC1-999 - Abstract
Tailoring optical bandgap of ZnO nanostructured thin films doped with different elements facilitates potential material for photonic applications. Different methods of fabrication process result in different optical and structural properties for the same amount of Mg content. Therefore, details investigation of structural and optical parameters, and their correlation need to be revealed to utilize the fabricated thin films. In this work, Mg-doped ZnO thin film of 200 nm thickness was fabricated by sol-gel spin coating method on a glass substrate for four different Mg content levels. Multiple layers were deposited by a spin coater to increase the film thickness. The prepared thin films were characterized by SEM, XRD, EDS, and UV–Vis spectroscopy. The spectroscopic analysis showed a uniform crystalline nanostructured surface with less structural defects, enhanced transmittance, and higher optical bandgap than that of pure ZnO nanostructured thin film. Change of Mg content from 2% to 8% facilitated tuning of bandgap in the range of 3.30–3.39 eV. Changing trend of structural and optical parameters with Mg content showed non-linear, non-monotonic relation. In-depth analysis of structural and optical properties provides crucial information to form a better view about bandgap dependency on structural parameters. Keywords: Mg-doped ZnO, MgZnO, Bandgap tuning, Sol-gel, Spin coating
- Published
- 2017
- Full Text
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93. Efficient amorphous silicon solar cells: characterization, optimization, and optical loss analysis
- Author
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Wayesh Qarony, Mohammad I. Hossain, M. Khalid Hossain, M. Jalal Uddin, A. Haque, A.R. Saad, and Yuen Hong Tsang
- Subjects
Physics ,QC1-999 - Abstract
Hydrogenated amorphous silicon (a-Si:H) has been effectively utilized as photoactive and doped layers for quite a while in thin-film solar applications but its energy conversion efficiency is limited due to thinner absorbing layer and light degradation issue. To overcome such confinements, it is expected to adjust better comprehension of device structure, material properties, and qualities since a little enhancement in the photocurrent significantly impacts on the conversion efficiency. Herein, some numerical simulations were performed to characterize and optimize different configuration of amorphous silicon-based thin-film solar cells. For the optical simulation, two-dimensional finite-difference time-domain (FDTD) technique was used to analyze the superstrate (p-i-n) planar amorphous silicon solar cells. Besides, the front transparent contact layer was also inquired by using SnO2:F and ZnO:Al materials to improve the photon absorption in the photoactive layer. The cell was studied for open-circuit voltage, external quantum efficiency, and short-circuit current density, which are building blocks for solar cell conversion efficiency. The optical simulations permit investigating optical losses at the individual layers. The enhancement in both short-circuit current density and open-circuit voltage prompts accomplishing more prominent power conversion efficiency. A maximum short-circuit current density of 15.32 mA/cm2 and an energy conversion efficiency of 11.3% were obtained for the optically optimized cell which is the best in class amorphous solar cell. Keywords: Superstrate p-i-n, Power loss, Quantum efficiency, Short circuit current, FDTD
- Published
- 2017
- Full Text
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94. Modeling of self-assembled monolayers (SAMs) of Octadecanethiol and Hexadecanethiol on gold (Au) and silver (Ag)
- Author
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M. Jalal Uddin, M. Khalid Hossain, Mohammad I. Hossain, Wayesh Qarony, S. Tayyaba, M.N.H. Mia, M.F. Pervez, and S. Hossen
- Subjects
Physics ,QC1-999 - Abstract
This work proposes a modeling of self-assembled monolayers (SAMs) to assess the quality of SAM layers in terms of their leaky behavior. In the modeling, electrochemical impedance spectroscopy (EIS) and a conceptual and simplified resistance-resistance-capacitance (RRC) electrical model from an electrochemical setup were demonstrated. Based on the model, Matlab-based simulation was carried out to find out the suggestive low frequency measurement for analyzing the defective monolayers. Finally, the developed electrical model facilitated the interpretation of the EIS spectra measured in the range of 10 Hz to 100 kHz and provided the capacitance, resistance and thickness of the monolayer. Thus the proposed model could be considered as a powerful tool to characterize the defective SAMs, which was very specific to determine the resistive behavior of the self-assembled monolayers prepared for shorter adsorption time. Keywords: Self-assembled monolayers (SAMs), Octadecanethiol (ODT), Hexadecanethiol (HDT, Impedance, Capacitance of the SAM (CSAM), Resistance of the SAM (RSAM)
- Published
- 2017
- Full Text
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95. Study and analysis the Cu nanoparticle assisted texturization forming low reflective silicon surface for solar cell application
- Author
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M. K. Basher, R. Mishan, S. Biswas, M. Khalid Hossain, M. A. R. Akand, and M. A. Matin
- Subjects
Physics ,QC1-999 - Abstract
Monocrystalline silicon solar cells with photo-absorbing morphology can amplify light-trapping properties within the absorber layer and help to fabricate cost-effective solar cells. In this paper, the effect of different parameters namely temperature and time of Cu-assisted chemical etching was thoroughly investigated for the optimization of the light absorption properties. P-type monocrystalline wafers were selectively treated with Cu(NO3)2.3H2O:HF:H2O2:DI water solution at 50 °C for five different time duration. The entire process was repeated at five different temperatures for 20min as well to study the relation between etching temperature and surface reflectance. Sonication bathing was used for the removal of the deposited Cu atoms from the surface with the variation of time and the effect was examined using energy dispersive spectroscopy (EDS). Field emission scanning electron microscopy (FESEM) and UV/VIS spectroscopy were conducted to study the surface morphology and light absorbance respectively. Inverted shapes almost similar to inverted pyramids or porous surface were found randomly on the surface of the wafer. The effect of temperature was found more significant compared to the effect of time variation. An optimum light reflectance was found at 50 °C for 20 min of texturization. Atomic force microscopy (AFM) of the textured sample revealed the average depth of pyramidal shape was about 1.58 μm. EDS results showed a proportional relation between time and Cu removal process, and a complete Cu atoms free textured surface after 25 min of sonication bathing. Therefore, a suitable Cu-assisted texturization technique was found, which could enable lowering the photo-reflectance below 1% without any antireflection coating.
- Published
- 2019
- Full Text
- View/download PDF
96. Study on the mechanical, electrical and optical properties of metal-oxide nanoparticles dispersed unsaturated polyester resin nanocomposites
- Author
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M.T. Rahman, Md. Asadul Hoque, G.T. Rahman, M.A. Gafur, Ruhul A. Khan, and M. Khalid Hossain
- Subjects
Physics ,QC1-999 - Abstract
In this work, unsaturated polyester resin matrix based polymer nanocomposites were fabricated incorporating sol-gel synthesized Fe2O3, TiO2 and co-precipitation synthesized NiFe2O4 nanoparticles. The individual and synergic effect of nanoparticles on mechanical, electrical and optical properties in polymer matrix was evaluated. The maximum improvement in tensile strength (21.62%), Young’s modulus (6.56%) and Vickers microhardness number was found in NiFe2O4 loaded nanocomposite. Both the highest DC electrical conductivity and the lowest resistivity were found in (Fe2O3 + TiO2 + NiFe2O4) nanoparticles dispersed nanocomposite. The maximum improvement in light absorbance (30.38%) in UV–Vis range was found in Fe2O3 incorporated nanocomposite as well as the lowest (18.96%) optical energy band gap was found in NiFe2O4 nanoparticles dispersed nanocomposite. These nanocomposites may find its potential use in industrial sectors as well as in light shielding applications. Keywords: Unsaturated polyester resin, Inorganic nanoparticles, Polymer nanocomposites, Mechanical, electrical and optical properties, Fe2O3, TiO2, NiFe2O4 nanoparticle
- Published
- 2019
- Full Text
- View/download PDF
97. Comparative Overview of the Performance of Cementitious and Non-Cementitious Nanomaterials in Mortar at Normal and Elevated Temperatures
- Author
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M. Arsalan Khan, M. Khalid Imam, Kashif Irshad, Hafiz Muhammad Ali, Mohd Abul Hasan, and Saiful Islam
- Subjects
nano-mortar ,fresh-state properties ,mechanical properties ,durability properties ,microstructural characterization ,elevated temperature ,Chemistry ,QD1-999 - Abstract
Nanotechnology has emerged as a field with promising applications in building materials. Nanotechnology-based mortars are examples of such building materials that have widespread applications in the construction industry. The main nanomaterials used in mortars include nano-silica, nano-magnesium oxide, nano-alumina, nano-titanium oxide, nano-zinc oxide, nano-clay, and nano-carbon. This review paper presents a summary of the properties and effects of these nanomaterials on cement mortar in terms of its fresh-state and hard-state properties. The fresh-state properties include the setting time, consistency, and workability, while the hard-state properties include mechanical properties such as compressive, flexural, tensile strengths, as well as the elasticity modulus, in addition to durability properties such as water absorption, shrinkage strain, strength loss due to freeze–thaw cycles, and chloride penetration, among others. Different nanomaterials cause different physical and chemical alterations within the microstructures of cement mortar. Therefore, the microstructural characterization and densification of mortar are discussed in detail at varying temperatures. In general, the involvement of nanomaterials in cement mortar influences the fresh-state properties, enhances the mechanical properties, and impacts the durability properties, while reducing the porosity present in the mortar matrix. Cementitious nanomaterials can create a pathway for the easy injection of binding materials into the internal microstructures of a hydration gel to impact the hydration process at different rates, whereas their non-cementitious counterparts can act as fillers. Furthermore, the research gaps and future outlook regarding the application of nanomaterials in mortar are discussed.
- Published
- 2021
- Full Text
- View/download PDF
98. High-Performance Plasmonic Biosensor for Blood Cancer Detection: Achieving Ultrahigh Figure-of-Merit
- Author
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Singh, Yashaswini, Mishra, Adarsh Chandra, Yadav, Sapana, Jaiswal, Laxmi, Lohia, Pooja, Dwivedi, D. K., Yadav, R. K., Eldesoky, Gaber E., and Hossain, M. Khalid
- Published
- 2024
- Full Text
- View/download PDF
99. Numerical investigation and optimization of highly efficient and stable organic solar cells: OghmaNano (GPVDM) framework
- Author
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Gogoi, Dipankar, Hossain, M. Khalid, Das, T. D., Toki, Gazi F. I., Shahatha, Sara H., Mohammad, M. R., Albaqami, Munirah D., and Mohammad, Saikh
- Published
- 2024
- Full Text
- View/download PDF
100. Green Synthesis of Silver Oxide Nanoparticles Using Plectranthus amboinicus and Solanum trilobatum Extracts as an Eco-friendly Approach: Characterization and Antibacterial Properties
- Author
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Mohanaparameswari, S., Balachandramohan, M., Kumar, K. Ganesh, Revathy, M. S., Sasikumar, P., Rajeevgandhi, C., Vimalan, M., Pugazhendhi, S., Batoo, Khalid Mujasam, Hussain, Sajjad, Albukhaty, Salim, Sulaiman, Ghassan M., and Hossain, M. Khalid
- Published
- 2024
- Full Text
- View/download PDF
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