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Our case details the atypical presentation of postpartum pituitary apoplexy in a 20-year-old female, who exhibited general weakness, dizziness, and brief loss of consciousness following an uncomplicated vaginal delivery. Despite normal vital signs except for bradycardia, imaging revealed a pituitary hemorrhage, leading to the diagnosis of pituitary apoplexy. Managed conservatively with IV hydrocortisone and intensive care, the patient experienced persistent bradycardia and severe abdominal pain, requiring transfer to another ICU. This case highlights the diagnostic challenges posed by the rarity and complexity of pituitary apoplexy during pregnancy and the postpartum period, emphasizing the importance of early diagnosis and tailored treatment strategies. The discussion further contrasts this case with existing literature, particularly in the context of postpartum pituitary apoplexy, and explores the broader implications for managing such rare cases, reinforcing the viability of conservative management in the absence of visual field disturbances.

Objective: To assess the correlation between patients with type 1 diabetes mellitus (T1DM) and dental caries outcomes, including missing teeth, missing surface, filling teeth, filling surface, plaque index, gingival index, and calculus index. Methods: A comprehensive search was performed across EMBASE, Medline/Pubmed, and Web of Science databases from inception until February 20, 2023. Observational and interventional studies reporting dental caries outcomes in patients with T1DM were included. A random effects meta-analysis was performed to estimate the pooled effect sizes and 95 % confidence intervals. Results: Thirty-three studies met the criteria for inclusion in the meta-analysis, which revealed that patients with T1DM had a reduced risk of missing teeth in comparison to those without diabetes (control group), with a mean difference (MD) of -0.03, CI 95 % [-0.03, -0.03]. No significant differences were found in missing surface, filling teeth, filling surface, or calculus index between T1DM and non-diabetic groups. However, patients with T1DM had a significantly higher plaque index (MD: 0.47, CI 95 % [0.06, 0.89]) than the non-diabetic group. The overall MD in DFMT between the DM and non-DM groups was 0.47 (95 % CI: 0.13, 0.82). The gingival index showed no significant difference between the groups. Conclusion: This meta-analysis suggests that patients with T1DM have a higher plaque index than the non-diabetic group, whereas no significant differences were observed in other dental caries outcomes. Because of the considerable variability identified in certain analyses, additional research employing more extensive sample sizes and rigorous methodologies is required to validate these results.

Edge sensing (ES) systems employ users’ owned smart devices with built-in sensors to gather data from users’ surrounding environments and use their processors to carry out edge computing tasks. Therefore, ES is emerging as a potential solution for remote sensing challenges. Additionally, ES systems are recognized for their favorable characteristics, including efficient time and cost management, scalability, and the ability to gather real-time data. To improve the performance of ES systems, enormous efforts have been made to enhance the quality of data (QoD) and the systems’ spatiotemporal coverage. Moreover, the research community has focused on developing better incentive schemes, as user incentivization is essential for enhancing system performance. In this study, we assess the impact of users’ mobility and availability on the spatiotemporal coverage and QoD of ES systems, taking into account the heterogeneity of users. We propose a distribution-aware and learning-based dynamic incentive scheme. Specifically, we consider the randomness of users’ mobility and velocity using a 2-dimensional random waypoint (RWP) model and support the learning-based incentive scheme with a long short-term memory (LSTM) model. The LSTM model utilizes the users’ historical data to predict their availability to perform the sensing tasks. The learning-based incentive scheme is further used to enhance system performance and effectively manage the trade-off between quality and cost, by recruiting users based on the required quality and cost constraints, to meet the minimum quality requirement within a constrained incentivization budget.

A prospective clinical trial was conducted on 30 cats suffering from pyometritis to investigate the multimodal analgesic efficacy of ropivacaine-tizanidine (RT) combination through intraperitoneal (IP) administration during ovariohysterectomy. Cats were randomly assigned into three groups whereby group RT received 0.5% ropivacaine (1 mg/kg) and tizanidine (10 μg/kg) (IP), group B received 0.5% bupivacaine (2 mg/kg) (IP), and group R received only 0.5% ropivacaine (1 mg/kg) (IP). It was observed that duration for anesthetic recovery (P

We report on a portable dielectrophoresis manipulation platform, for the positioning and immobilization of small dielectric objects, such as cells or microbes, using a circular array of up to six symmetrically arranged and independently controllable micro-electrodes. The system’s micro-controller-instructed electronic drivers can be operated in three distinct modes. We demonstrate the system’s function by actuating bacterial cells to specific locations and orientations within a region of interest. Using a deep learning approach, we map voltage phase combinations of the six electrodes to geometrical trap position locations, thereby facilitating smooth trajectory planning.

Th e study was a prospective trial, planned to determine the molecular epidemiology of ehrlichiosis in dogs through blood smear microscopy and Polymerase chain reaction (PCR). A total of 384 cephalic blood samples were collected from domestic (n=288) and stray dogs (n=96) belonging to varied demographics. Molecular detection of Ehrlichia spp. was conducted through PCR by targeting 16S rRNA gene using the genus specific primers. Final logistic regression analysis revealed that previous history of tick infestation and housing hygiene were significant (P

The administration of corticosteroids may have possible hazards, ranging from minor adverse medication reactions to more serious considerations. We aimed to assess levels of public awareness concerning corticosteroid use, side effects, and predictors of its use. A cross-sectional study was conducted online throughout the period of May to July 2023. The present investigation utilized a previously developed questionnaire tool. The study encompassed a cohort of 732 individuals. Upon inquiry regarding the adverse effects of corticosteroid treatment, the participants predominantly reported weight gain, skin alterations, and fluid retention leading to breathing difficulties, constituting 44.4%, 30.3%, and 27.7% of the responses, respectively. The prevailing adverse effects observed in individuals using corticosteroids were weight gain, alterations in mood, and changes in skin characteristics, which accounted for 38.1%, 25.7%, and 21.8% of reported cases, respectively. Individuals within the age range of 41–50 years and those who are currently not working show a higher propensity for utilizing corticosteroids in comparison to other demographic groups (p < 0.05). The level of general public knowledge about corticosteroids and the side effects connected with them in Saudi Arabia was adequate. Demographic factors, such as age, gender, and education, have an impact on the use of corticosteroids.

In today’s Telecom market, Telecom operators find a big value in introducing valuable services to users based on their location, both for emergency and ordinary situations. This drives the research for outdoor localization using different wireless technologies. Long Term Evolution (LTE) is the dominant wireless technology for outdoor cellular networks. This paper introduces DeepFeat: A deep-learning-based framework for outdoor localization using a rich features set in LTE networks. DeepFeat works on the mobile operator side, and it leverages many mobile network features and other metrics to achieve high localization accuracy. In order to reduce computation and complexity, we introduce a feature selection module to choose the most appropriate features as inputs to the deep learning model. This module reduces the computation and complexity by around 20.6% while enhancing the system’s accuracy. The feature selection module uses correlation and Chi-squared algorithms to reduce the feature set to 12 inputs only regardless of the area size. In order to enhance the accuracy of DeepFeat, a One-to-Many augmenter is introduced to extend the dataset and improve the system’s overall performance. The results show the impact of the proper features selection adopted by DeepFeat on the system’s performance. DeepFeat achieved median localization accuracy of 13.179m in an outdoor environment in a mid-scale area of 6.27Km2. In a large-scale area of 45Km2, the median localization accuracy is 13.7m. DeepFeat was compared to other state-of-the-art deep-learning-based localization systems that leverage a small number of features. We show that using DeepFeat’s carefully selected features set enhances the localization accuracy compared to the state-of-the-art systems by at least 286%.

Objectives: In the event of cardiac arrest, cardiopulmonary resuscitation (CPR) is an emergency procedure used to maintain the heart and lungs functional simultaneously. The do-not-resuscitate (DNR) order prohibits CPR and is therefore legally required. Despite this, a DNR remains a delicate and contentious issue that places physicians in morally ambiguous situations. This study aimed to assess Saudi citizens’ understanding of DNR orders, prior exposure to them, and preferences for DNR conversations. Methods: This was an online cross-sectional study that was conducted between January and April 2023 and aimed to assess the knowledge regarding DNR orders among Saudi populations. This study adapted a previously developed questionnaire tool by Al Ahmadi et al., which examined the knowledge and attitude toward do-not-resuscitate among patients and their relatives visiting outpatient clinics. Binary logistic regression analysis was the mean knowledge score for the study participants. Results: A total of 920 participants were involved in this study. Almost half of the study participants (49.6%) reported that they had heard of DNR before. The most commonly reported source of their information on DNR was healthcare providers (58.2%). The mean knowledge score of the study participants was 1.9 (1.3) out of 6, which is equal to 31.7% of the total maximum score. This demonstrates the weak level of knowledge about DNR among the general public. Females, divorced, and those who had a post-graduate level of education were more likely to be knowledgeable of DNR compared to others (p < 0.05). Around one-quarter of the study participants showed agreement with DNR. More than half of them (59.5%) believe that physicians should be involved in DNR decision making. Conclusions: Saudi Arabia’s general community has limited knowledge of DNR. It is recommended that healthcare professionals increase patients’ and caregivers’ understanding of this concept. This will improve the planning and the provision of end-of-life care.

Abstract A novel approach for automated high throughput NMR spectroscopy with improved mass-sensitivity is accomplished by integrating microfluidic technologies and micro-NMR resonators. A flow system is utilized to transport a sample of interest from outside the NMR magnet through the NMR detector, circumventing the relatively vast dead volume in the supplying tube by loading a series of individual sample plugs separated by an immiscible fluid. This dual-phase flow demands a real-time robust sensing system to track the sample position and velocities and synchronize the NMR acquisition. In this contribution, we describe an NMR probe head that possesses a microfluidic system featuring: (i) a micro saddle coil for NMR spectroscopy and (ii) a pair of interdigitated capacitive sensors flanking the NMR detector for continuous position and velocity monitoring of the plugs with respect to the NMR detector. The system was successfully tested for automating flow-based measurement in a 500 MHz NMR system, enabling high resolution spectroscopy and NMR sensitivity of 2.18 nmol s1/2 with the flow sensors in operation. The flow sensors featured sensitivity to an absolute difference of 0.2 in relative permittivity, enabling distinction between most common solvents. It was demonstrated that a fully automated NMR measurement of nine individual 120 μL samples could be done within 3.6 min or effectively 15.3 s per sample.

Abstract This paper presents an experimental and modeling studies on the thermodynamic inhibition effects of the mixture of monoethlyene glycol (MEG) and glycine (Gly) on the carbon dioxide hydrate phase boundary condition. The monoethlyene glycol and glycine (1:1) mixture inhibition effects were investigated at concentrations of 5, 10, and 15 wt.% and pressure ranges from 2.0–4.0 MPa. The effects of the proposed mixture on the carbon dioxide hydrate phase boundary were evaluated by measuring the dissociation temperature of carbon dioxide hydrate using a T-cycle method. The synergistic effect was evaluated based on comparison with pure MEG and Gly data. The results show that 15 wt.% of MEG and Gly mixture displays the highest inhibition effect compared to the 5 and 10 wt.% mixtures, respectively. However, the synergistic effect is higher at 10 wt.%. Dickens' model was also adopted to predict the phase equilibrium data of CO2 hydrates in the presence of the mixture. The modified model successfully predicted the data within a maximum error of ± 0.52 K.

Hydrate-based technology has yet to find its way to commercial applications due to several issues, including formation conditions and slow kinetics. Several solid particles were introduced to speed up hydrate formation. However, these solid compounds have given contradictory results. This study investigated the effect of high thermal conductive metallic nanofluids of silver (Ag) and copper (Cu) on CH4 and CO2 hydrates. The solid particles were suspended in a 0.03 wt% SDS aqueous solution, and the results were compared with the 0.03 wt% SDS and deionized water samples. A stirred tank batch reactor was used to conduct the thermodynamic and kinetic experiments. The thermodynamic study revealed that 0.1 wt% of solid particles do not shift the equilibrium curve significantly. The kinetic evaluation, including induction time, the initial rate of gas consumption, half-completion time, t50 and semi-completion time, t95, gas uptake, and storage capacity, have been studied. The results show that the Ag and Cu promote CH4 hydrates while they inhibit or do not significantly influence the CO2 hydrates formation. A predictive correlation was introduced to get the apparent rate constant of hydrate formation in the presence of metal-based fluid at the concentrations range of 0.005–0.1 wt%.

Gas hydrate inhibitors have proven to be the most feasible approach to controlling hydrate formation in flow assurance operational facilities. Due to the unsatisfactory performance of the traditional inhibitors, novel effective inhibitors are needed to replace the existing ones for safe operations within constrained budgets. This work presents experimental and modeling studies on the effects of nonionic surfactants as kinetic hydrate inhibitors. The kinetic methane hydrate inhibition impact of Tween-20, Tween-40, Tween-80, Span-20, Span-40, and Span-80 solutions was tested in a 1:1 mixture of a water and oil multiphase system at a concentration of 1.0% (v/v) and 2.0% (v/v), using a high-pressure autoclave cell at 8.70 MPa and 274.15 K. The results showed that Tween-80 effectively delays the hydrate nucleation time at 2.5% (v/v) by 868.1% compared to the blank sample. Tween-80 is more effective than PVP (a commercial kinetic hydrate inhibitor) in delaying the hydrate nucleation time. The adopted models could predict the methane hydrate induction time and rate of hydrate formation in an acceptable range with an APE of less than 6%. The findings in this study are useful for safely transporting hydrocarbons in multiphase oil systems with fewer hydrate plug threats.

Sickle cell anaemia (SCA) is a common haemoglobinopathy among people from the Middle East, the Afro-Caribbean region, the Mediterranean and East India. While osteomyelitis of the long bones is a welldocumented complication of SCA, there are few documented cases of SCA patients presenting with jaw osteomyelitis. We report three SCA patients with chronic jaw osteomyelitis who presented to the Department of Oral Health, Sultan Qaboos University Hospital, Muscat, Oman, between 2009 and 2013. Two of the patients had osteomyelitis of the mandible and the third had osteomyelitis of the maxilla. In addition, a brief review of the literature is presented focusing on the clinical presentation, diagnosis and management of jaw osteomyelitis among patients with SCA.

This paper presents a data driven framework for performance optimisation of Narrow-Band IoT user equipment. The proposed framework is an edge micro-service that suggests one-time configurations to user equipment communicating with a base station. Suggested configurations are delivered from a Configuration Advocate, to improve energy consumption, delay, throughput or a combination of those metrics, depending on the user-end device and the application. Reinforcement learning utilising gradient descent and genetic algorithm is adopted synchronously with machine and deep learning algorithms to predict the environmental states and suggest an optimal configuration. The results highlight the adaptability of the Deep Neural Network in the prediction of intermediary environmental states, additionally the results present superior performance of the genetic reinforcement learning algorithm regarding its performance optimisation.

The aim of this study was to review the aetiology, presentation and management of these patients with upper gastrointestinal bleeding (UGIB) at a tertiary children’s unit in the United Kingdom. This was a retrospective single-institution study on children (

Considered as the second deadliest disease globally, cancer has captured the attention of researchers who have been trying with perseverance to decode its hidden aspects, to find new prognosis methods, and to develop better and more effective treatments. Plants have continuously offered an excess of unique secondary metabolites with remarkable biological applications. Alkaloids, one of the most abundant metabolites, constitute a large conglomerate of basic heterocyclic nitrogen-containing natural compounds which are normally produced by plants as toxic substances. Out of the 27,000 different alkaloids, more than 17,000 have displayed diversified pharmacological properties including anticancer activities. These metabolites have been classified either according to their chemical structures or their taxonomic origin. None of the researched alkaloids have been classified according to their molecular mechanism of action against cancer. In fact, only a fraction of the tremendous number of anticancer alkaloids has been copiously mentioned in journals. Here, we aim to provide a summary of the literature on some of the promising anticancer alkaloids that have not been well discussed previously and to classify them according to their molecular mechanisms of action. This review will provide a better understanding of the anticancer mechanisms of these promising natural products that are a rich reservoir for drug discovery.

Aim. To evaluate the efficacy of the PeristeenⒸ transanal irrigation system when treating faecal incontinence in children due to chronic idiopathic constipation. Methods. A retrospective study was conducted of the first cohort of patients affected with faecal incontinence and referred to our centre for PeristeenⒸ transanal irrigation treatment between January 2010 and December 2012. Patients with neurogenic bowel disturbance were excluded. A previously described and validated faecal continence scoring system was used to assess bowel function and social problems before and after treatment with PeristeenⒸ. Results. 13 patients were referred for PeristeenⒸ transanal irrigation during the study period. Mean time of using PeristeenⒸ was 12.6 months (±0.6 months) and mean length of follow-up was 21.2 months (±0.9 months). All patients were noted to have an improvement in their faecal continence score, with a mean improvement from 9.7 ± 1.4 to 14.8 ± 2.7 (P=0.0008) and a reduction in episodes of soiling and increasing in quality of life scores. Conclusion. In this initial study, PeristeenⒸ appears to be a safe and effective bowel management system, which improves bowel function and quality of life in children affected with faecal incontinence as a result of chronic idiopathic constipation, Hirschsprung’s disease, and anorectal malformations.

Introduction Science has become a very narrow and qualified study of the universe. Its descriptions of reality are restricted to objective, publicly extended and impersonal notions. This characterization of reality is, in the Goethean sense, an utterly oppressive impasse to the subjective human condition. Thus did Nietzsche exclaim, “the nihilistic consequences of our natural sciences from its pursuits . . . there follows ultimately a selfdecomposition, a turning against itself.” One sees a disunited system of thought, where objective designs are studied using objective methods and tools, thereby leaving out many of the subjective and private characteristics of reality. How then can science claim to be a study of reality and the universe, when it does not have the tools to study even the most fundamental component of reality, the self? The gap between the subject and object was partly created by the Empiricist tradition and by Kant with his discussions on the “noumena” and “phenomena.” This dualism within the western world-view has culminated in a very disunited and incoherent description of reality. In physics, efforts are being made to create a “theory of everything” (TOE), but it has been quite a task, because of the inherent dualism and lack of connection between ideas, both in the natural sciences and the social sciences. As far as western art, it claims to be of an “absolute” and “universal” nature, so general as to include the whole universe, and beyond, within a single preview. Art relates to the subjective and inner feelings of an individual or a society at a particular time. As posited by the German Idealists, it actually submerges the object and the subject into But this bridge between the objective and the subjective is only an illusion whose disastrous effects can be seen in the modem conception of aesthetic autonomy. The negative production of an autonomous art form is a direct and implicit result of Kantian dualisms$ which pervades the ...

The development of carbon dots (CDs), either using green or chemical precursors, has inevitably led to their wide range application, from bioimaging to optoelectronic devices. The reported precursors and properties of these CDs have opened new opportunities for the future development of high-quality CDs and applications. Green precursors were classified into fruits, vegetables, flowers, leaves, seeds, stem, crop residues, fungi/bacteria species, and waste products, while the chemical precursors were classified into acid reagents and non-acid reagents. This paper quickly reviews ten years of the synthesis of CDs using green and chemical precursors. The application of CDs as sensing materials in optical sensor techniques for environmental monitoring, including the detection of heavy metal ions, phenol, pesticides, and nitroaromatic explosives, was also discussed in this review. This profound review will offer knowledge for the upcoming community of researchers interested in synthesizing high-quality CDs for various applications.

Abnormality of dopamine (DA), a vital neurotransmitter in the brain's neuronal pathways, causes several neurological diseases. Rapid and sensitive sensors for DA detection are required for early diagnosis of such disorders. Herein, a carbon quantum dot (CQD)-based refractive index surface plasmon resonance (SPR) sensor was designed. The sensor performance was evaluated for various concentrations of DA. Increasing DA levels yielded blue-shifted SPR dips. The experimental findings revealed an excellent sensitivity response of 0.138°/pM in a linear range from 0.001 to 100 pM and a high binding affinity of 6.234 TM -1 . The effects of varied concentrations of DA on the optical characteristics of CQD thin film were further proved theoretically. Increased DA levels decreased the thickness and real part of the refractive index of CQD film, according to fitting results. Furthermore, the observed reduction in surface roughness using AFM demonstrated that DA was bound to the sensor layer. This, in turn, explained the blue shift in SPR reflectance curves. This optical sensor offers great potential as a trustworthy solution for direct measurement due to its simple construction, high sensitivity, and other sensing features.

Due to the crucial role of dopamine (DA) in health and peripheral nervous systems, it is particularly important to develop an efficient and accurate sensor to monitor and determine DA concentrations for diagnostic purposes and diseases prevention. Up to now, using surface plasmon resonance (SPR) sensors in DA determination is very limited and its application still at the primary stage. In this work, a simple and ultra-sensitive SPR sensor was constructed for DA detection by preparation of chitosan- graphene quantum dots (CS-GQDs) thin film as the sensing layer. Other SPR measurements were conducted using different sensing layers; GQDs, CS for comparison. The proposed thin films were prepared by spin coating technique. The developed CS-GQDs thin film-based SPR sensor was successfully tested in DA concentration range from 0 fM to 1 pM. The designed SPR sensor showed outstanding performance in detecting DA sensitively (S = 0.011°/fM, R 2  = 0.8174) with low detection limit of 1.0 fM has been achieved for the first time. The increased angular shift of SPR dip, narrow full width half maximum of the SPR curves, excellent signal-to-noise ratio and figure of merit, and a binding affinity constant (K A ) of 2.962 PM -1 demonstrated the potential of this sensor to detect DA with high accuracy. Overall, it was concluded that the proposed sensor would serve as a valuable tool in clinical diagnostic for the serious neurological disorders. This in turns has a significant socio-economic impact., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Insecticides are enormously important to industry requirements and market demands in agriculture. Despite their usefulness, these insecticides can pose a dangerous risk to the safety of food, environment and all living things through various mechanisms of action. Concern about the environmental impact of repeated use of insecticides has prompted many researchers to develop rapid, economical, uncomplicated and user-friendly analytical method for the detection of insecticides. In this regards, optical sensors are considered as favorable methods for insecticides analysis because of their special features including rapid detection time, low cost, easy to use and high selectivity and sensitivity. In this review, current progresses of incorporation between recognition elements and optical sensors for insecticide detection are discussed and evaluated well, by categorizing it based on insecticide chemical classes, including the range of detection and limit of detection. Additionally, this review aims to provide powerful insights to researchers for the future development of optical sensors in the detection of insecticides.

This paper proposes a novel idea to enhance the sensitivity and selectivity of surface plasmon resonance (SPR) optical sensor for detection of dengue virus type-2 envelope proteins (DENV-2 E-proteins) using polyamidoamine (PAMAM) dendrimer biopolymer-based nanocomposite thin film. For this purpose, two ranges of DENV-2 E-protein concentrations, i.e., 0.000008-0.0001 nM and 0.00008-0.005 nM were evaluated, and the lowest detectable concentration was achieved at 0.00008 nM. The incorporation of PAMAM dendrimer-based nanocomposite thin film with an SPR sensor exhibited a significant increase in sensitivity and binding affinity to a lower range DENV-2 E-protein concentrations. Moreover, the proposed sensor displayed good selectivity towards DENV-2 E-proteins and have an average recovery of 80-120%. The findings of this study demonstrated that PAMAM dendrimer-based nanocomposite thin film combined with SPR sensor is a promising diagnostic tool for sensitive and selective detection of DENV-2 E-proteins.

Arecanut husk (AH) was selected as a material for silica replacement in the synthesis process of glass-ceramics zinc silicate and also the fact that it has no traditional use and often being dumped and results in environmental issues. The process of pyrolysis was carried out at temperature 700 °C and above based on thermogravimetric analysis to produce arecanut husk ash (AHA). The average purity of the silica content in AHA ranged from 29.17% to 45.43%. Furthermore, zinc oxide was introduced to AHA and zinc silicate started to form at sintering temperature 700 °C and showed increased diffraction intensity upon higher sintering temperature of 600 °C to 1000 °C based on X-ray diffraction (XRD) analysis. The grain sizes of the zinc silicate increased from 1011 nm to 3518 nm based on the morphological studies carried out by field emission scanning electron microscopy (FESEM). In addition, the optical band gap of the sample was measured to be in the range from 2.410 eV to 2.697 eV after sintering temperature. From the data, it is believed that a cleaner production of low-cost zinc silicate can be achieved by using arecanut husk and have the potential to be used as phosphors materials.

In this paper, the structural and optical properties of ZnO-SiO 2 -based ceramics fabricated from oil palm empty fruit bunch (OPEFB) were investigated. The OPEFB waste was burned at 600, 700 and 800 °C to form palm ash and was then treated with sulfuric acid to extract silica from the ash. X-ray fluorescence (XRF) and X-ray diffraction (XRD) analyses confirmed the existence of SiO 2 in the sample. Field emission scanning electron microscopy (FESEM) showed that the particles displayed an irregular shape and became finer after leaching. Then, the solid-state method was used to produce the ZnO-SiO 2 composite and the samples were sintered at 600, 800, 1000, 1200 and 1400 °C. The XRD peaks of the Zn 2 SiO 4 showed high intensity, which indicated high crystallinity of the composite. FESEM images proved that the grain boundaries were larger as the temperature increased. Upon obtaining the absorbance spectrum from ultraviolet-visible (UV-Vis) spectroscopy, the energy band gaps obtained were 3.192, 3.202 and 3.214 eV at room temperature, 600 and 800 °C, respectively, and decreased to 3.127, 2.854 and 2.609 eV at 1000, 1200 and 1400 °C, respectively. OPEFB shows high potential as a silica source in producing promising optical materials.

The optical constants of Para-Toluene sulfonic acid-doped polyaniline (PANI), PANIchitosan composites, PANI-reduced graphene-oxide composites and a ternary composite comprising of PANI, chitosan and reduced graphene-oxide dispersed in diluted p-toluene sulfonic acid (PTSA) solution and N -Methyl-2-Pyrrolidone (NMP) solvent have been evaluated and compared. The optical constant values were extracted from the absorbance spectra of thin layers of the respective samples. The potential utilization of the materials as the active sensing materials of surface plasmon resonance biosensors has also been assessed in terms of the estimated value of the penetration depth through a dielectric medium. The results show a reasonable dependence of the optical constant parameters on the solvent type. Higher real part refractive index ( n ) and real part complex dielectric permittivity ( ε ') values were observed for the samples prepared using PTSA solution, while higher optical conductivity values were observed for the NMP-based samples due to their relatively higher imaginary part refractive index ( k ) and imaginary part complex dielectric permittivity ( ε ″) values. In addition, NMP-based samples show improvement in terms of the penetration depth through a dielectric medium by around 9.5, 1.6, 4.4 and 2.9 times compared to PTSA-based samples for the PANI, PANI-chitosan, PANI-RGO and the ternary composites, respectively. Based on these, it is concluded that preparation of these materials using different dispersion solvents could produce materials of different optical properties. Thus, the variation of the dispersion solvent will allow the flexible utilization of the PANI and the composites for diverse applications.

In this study, synthesis and characterization of chitosan/maghemite (Cs/Fe 2 O 3 ) composites thin film has been described. Its properties were characterized using Fourier transform infrared spectroscopy (FTIR), atomic force microscopy (AFM) and ultraviolet-visible spectroscopy (UV-Vis). FTIR confirmed the existence of Fe-O bond, C-N bond, C-C bond, C-O bond, O=C=O bond and O-H bond in Cs/Fe 2 O 3 thin film. The surface morphology of the thin film indicated the relatively smooth and homogenous thin film, and also confirmed the interaction of Fe 2 O 3 with the chitosan. Next, the UV-Vis result showed high absorbance value with an optical band gap of 4.013 eV. The incorporation of this Cs/Fe 2 O 3 thin film with an optical-based method, i.e., surface plasmon resonance spectroscopy showed positive response where mercury ion (Hg 2+ ) can be detected down to 0.01 ppm (49.9 nM). These results validate the potential of Cs/Fe 2 O 3 thin film for optical sensing applications in Hg 2+ detection.

The modification of graphene quantum dots (GQDs) may drastically enhance their properties, therefore resulting in various related applications. This paper reported the preparation of novel cetyltrimethylammonium bromide/hydroxylated graphene quantum dots (CTAB/HGQDs) thin film using the spin coating technique. The properties of the thin film were then investigated and studied. The functional groups existing in CTAB/HGQDs thin film were confirmed by the Fourier transform infrared (FTIR) spectroscopy, while the atomic force microscope (AFM) displayed a homogenous surface of the thin film with an increase in surface roughness upon modification. Optical characterizations using UV-Vis absorption spectroscopy revealed a high absorption with an optical band gap of 4.162 eV. Additionally, the photoluminescence (PL) spectra illustrated the maximum emission peak of CTAB/HGQDs thin film at a wavelength of 444 nm. The sensing properties of the as-prepared CTAB/HGQDs thin film were studied using a surface plasmon resonance technique towards the detection of several heavy metal ions (HMIs) (Zn 2+ , Ni 2+ , and Fe 3+ ). This technique generated significant results and showed that CTAB/HGQDs thin film has great potential for HMIs detection.

In this work, waste coconut husk ash was used to prepare a ZnO-SiO 2 composite. Solid-state technique was used to fabricate the composite due to its producibility, simple procedure as well as lower production cost. At high sintering temperatures ranging from 600 °C to 1000 °C, the X-ray diffraction (XRD) peaks of the Zn 2 SiO 4 showed high intensity, which indicated high crystallinity. Furthermore, the formation of broad bands of ZnO 4 , Si-O-Si, and SiO 4 were detected by Fourier transform infrared (FTIR) spectroscopy and the bands became narrower with the increment of sintering temperature. Besides, the morphological image from field emission scanning electron microscopy (FESEM) showed the formation of densely packed grains and smooth surface composite with the increase of sintering temperature. Upon obtaining the absorbance spectrum from Ultraviolet-Visible (UV-Vis) spectroscopy, the optical band gap was calculated to be 4.05 eV at 1000 °C. The correlation between the structural and optical properties of ZnO-SiO 2 composite was discussed in detail.

Great efforts have been devoted to the invention of environmental sensors as the amount of water pollution has increased in recent decades. Chitosan, cellulose and nanocrystalline cellulose are examples of biopolymers that have been intensively studied due to their potential applications, particularly as sensors. Furthermore, the rapid use of conducting polymer materials as a sensing layer in environmental monitoring has also been developed. Thus, the incorporation of biopolymer and conducting polymer materials with various methods has shown promising potential with sensitively and selectively toward heavy metal ions. In this feature paper, selected recent and updated investigations are reviewed on biopolymer and conducting polymer-based materials in sensors aimed at the detection of heavy metal ions by optical methods. This review intends to provide sufficient evidence of the potential of polymer-based materials as sensing layers, and future outlooks are considered in developing surface plasmon resonance as an excellent and valid sensor for heavy metal ion detection.

Dengue viral infection is one of the most common deadliest diseases and has become a recurrent issue for public health in tropical countries. Although the spectrum of clinical diagnosis and treatment have recently been established, the efficient and rapid detection of dengue virus (DENV) during viremia and the early febrile phase is still a great challenge. In this study, a dithiobis (succinimidyl undecanoate, DSU)/amine-functionalized reduced graphene oxide--polyamidoamine dendrimer (DSU/amine-functionalized rGO-PAMAM) thin film-based surface plasmon resonance (SPR) sensor was developed for the detection of DENV 2 E-proteins. Different concentrations of DENV 2 E-proteins were successfully tested by the developed SPR sensor-based system. The performance of the developed sensor showed increased shift in the SPR angle, narrow full-width-half-maximum of the SPR curve, high detection accuracy, excellent figure of merit and signal-to-noise ratio, good sensitivity values in the range of 0.08-0.5 pM (S = 0.2576°/pM, R 2 = 0.92), and a high equilibrium association constant (K A ) of 7.6452 TM -1 . The developed sensor also showed a sensitive and selective response towards DENV 2 E-proteins compared to DENV 1 E-proteins and ZIKV (Zika virus) E-proteins. Overall, it was concluded that the Au/DSU/amine-functionalized rGO-PAMAM thin film-based SPR sensor has potential to serve as a rapid clinical diagnostic tool for DENV infection.

In this work, sensitive detection of dengue virus type 2 E-proteins (DENV-2 E-proteins) was performed in the range of 0.08 pM to 0.5 pM. The successful DENV detection at very low concentration is a matter of concern for targeting the early detection after the onset of dengue symptoms. Here, we developed a SPR sensor based on self-assembled monolayer/reduced graphene oxide-polyamidoamine dendrimer (SAM/NH 2 rGO/PAMAM) thin film to detect DENV-2 E-proteins. Surface characterizations involving X-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FTIR) confirms the incorporation of NH 2 rGO-PAMAM nanoparticles in the prepared sensor films. The specificity, sensitivity, binding affinity, and selectivity of the SPR sensor were then evaluated. Results indicated that the variation of the sensing layer due to different spin speed, time incubation, and concentration provided a better interaction between the analyte and sensing layer. The linear dependence of the SPR sensor showed good linearity (R 2  = 0.92) with the lowest detection of 0.08 pM DENV-2 E-proteins. By using the Langmuir model, the equilibrium association constant was obtained at very high value of 6.6844 TM -1 (R 2  = 0.99). High selectivity of the SPR sensor towards DENV-2 E-proteins was achieved in the presence of other competitors.

Surface plasmon resonance (SPR) sensors as novel optical sensors for the detection of a variety of analytes have been receiving increasing attention and their sensitivity has become the research hotspot recently. In this study, the sensitivity of an SPR optical sensor was enhanced by modifying a gold thin film with a nanocrystalline cellulose (NCC)-based material for zinc ion (Zn 2+ ) detection that exists in the environment due to industrial processing. By replacing the gold thin film with a novel modified-gold thin film, Zn 2+ can be detected from the range of 0 to 10 ppm using SPR. It is believed that the Zn 2+ may interact with the negative charge molecules that exist on the modified-gold thin film, and this was confirmed via X-ray photoelectron spectroscopy (XPS). Moreover, this modified-gold-SPR has a high sensitivity of 1.892° ppm -1 up to 0.1 ppm with an enhanced detection of Zn 2+ as low as 0.01 ppm. The SPR results also followed the Langmuir isotherm model with a binding affinity of 1.927 × 10 3 M -1 , which further confirmed the sensitivity of the SPR sensor. In addition, using the modified-gold thin film, SPR has a higher affinity towards Zn 2+ compared to other metal ions, i.e. Ni 2+ , Fe 2+ , Cr 2+ , Mn 2+ , and Co 2+ ., Competing Interests: There are no conflicts of interest to declare., (This journal is © The Royal Society of Chemistry.)

In this study, the incorporation of surface plasmon resonance (SPR) spectroscopy with novel chitosan-graphene oxide/cadmium sulphide quantum dots (CdS QDs) active layer for cobalt ion (Co 2+ ) detection has been developed. The interaction of different Co 2+ concentrations with the novel modified active layer was monitored using the SPR technique. From the SPR results, detection range, sensitivity, full width at half maximum (FWHM), detection accuracy (DA) and signal-to-noise ratio (SNR) have been analysed. The results showed the detection range of this optical sensor was 0.01 to 10 ppm, and it was saturated for higher concentration of Co 2+ . The sensitivity obtained was 0.1188 ppm -1 for low concentration of Co 2+ ranged from 0.01 to 1 ppm. The FWHM and DA were consistent for all concentration of Co 2+ , while the SNR of the SPR signal increased with the Co 2+ concentration. The SPR angle shifts were also fitted using Langmuir, Freundlich and Sips (Langmuir-Freundlich) isotherm models, where Sips model fitted the best with the binding affinity of 0.939 ppm -1 . The results proved that the novel chitosan-graphene oxide/CdS QDs modified gold thin film can detect Co 2+ via SPR spectroscopy.

About 71% of the Earth's surface is covered with water. Human beings, animals, and plants need water in order to survive. Therefore, it is one of the most important substances that exist on Earth. However, most of the water resources nowadays are insufficiently clean, since they are contaminated with toxic metal ions due to the improper disposal of pollutants into water through industrial and agricultural activities. These toxic metal ions need to be detected as fast as possible so that the situation will not become more critical and cause more harm in the future. Since then, numerous sensing methods have been proposed, including chemical and optical sensors that aim to detect these toxic metal ions. All of the researchers compete with each other to build sensors with the lowest limit of detection and high sensitivity and selectivity. Graphene quantum dots (GQDs) have emerged as a highly potential sensing material to incorporate with the developed sensors due to the advantages of GQDs. Several recent studies showed that GQDs, functionalized GQDs, and their composites were able to enhance the optical detection of metal ions. The aim of this paper is to review the existing, latest, and updated studies on optical sensing applications of GQDs-based materials toward toxic metal ions and future developments of an excellent GQDs-based SPR sensor as an alternative toxic metal ion sensor.

The emergence of unintentional poisoning and uncontrolled vector diseases have contributed to sensor technologies development, leading to the more effective detection of diseases. In this study, we present the combination of graphene-based material with surface plasmon resonance technique. Two different graphene-based material sensor chips were prepared for rapid and quantitative detection of dengue virus (DENV) and cobalt ion (Co 2+ ) as an example of typical metal ions. As the fundamental concept of surface plasmon resonance (SPR) sensor that relies on the refractive index of the sensor chip surface, this research focused on the SPR signal when the DENV and Co 2+ interact with the graphene-based material sensor chip. The results demonstrated that the proposed sensor-based graphene layer was able to detect DENV and Co 2+ as low as 0.1 pM and 0.1 ppm respectively. Further details in the detection and quantification of analyte were also discussed in terms of sensitivity, affinity, and selectivity of the sensor.

Surface plasmon resonance (SPR) is a label-free optical spectroscopy that is widely used for biomolecular interaction analysis. In this work, SPR was used to characterize the binding properties of highly sensitive nanocrystalline cellulose-graphene oxide based nanocomposite (CTA-NCC/GO) towards nickel ion. The formation of CTA-NCC/GO nanocomposite has been confirmed by FT-IR. The SPR analysis result shows that the CTA-NCC/GO has high binding affinity towards Ni 2+ from 0.01 until 0.1 ppm with binding affinity constant of 1.620 × 10 3  M -1 . The sensitivity for the CTA-NCC/GO calculated was 1.509° ppm -1 . The full width at half maximum (FWHM), data accuracy (DA), and signal-to-noise ratio (SNR) have also been determined using the obtained SPR curve. For the FWHM, the value was 2.25° at 0.01 until 0.08 ppm and decreases to 2.12° at 0.1 until 10 ppm. The DA for the SPR curves is the highest at 0.01 until 0.08 ppm and lowest at 0.1 until 10 ppm. The SNR curves mirrors the curves of SPR angle shift where the SNR increases with the Ni 2+ concentrations. For the selectivity test, the CTA-NCC/GO has the abilities to differentiate Ni 2+ in the mixture of metal ions., (Copyright © 2018 Elsevier B.V. All rights reserved.)

In this research, surface plasmon resonance (SPR) spectroscopy was used for sensing copper ion by combining the SPR with nanocrystalline cellulose modified by hexadecyltrimethylammonium bromide and graphene oxide composite (CTA-NCC/GO) thin film. The binding of Cu 2+ on CTA-NCC/GO thin film was monitored by using SPR spectroscopy. By using the obtained SPR curve, detection range, binding affinity, sensitivity, full width at half maximum (FWHM), data accuracy (DA), and signal-to-noise ratio (SNR) have been calculated. The results showed that the sensor detection range was 0.01 until 0.5 ppm, and that it reached a saturation value. Moreover, the resonance angle shift followed the Langmuir isotherm model with a binding affinity constant of 4.075 × 10 3 M -1 . A high sensitivity of 3.271° ppm -1 also was obtained for low Cu 2+ concentration ranged from 0.01 to 0.1 ppm. For the FWHM, the lowest value calculated was at 0.08 and 0.1 ppm, which is 3.35°. The DA of the SPR signal consecutively highest at 0.08 and 0.1 ppm. Besides that, the SNR of the SPR signal increases with the Cu 2+ concentrations. The CTA-NCC/GO thin film morphological properties were also studied by using atomic force microscopy. The rms roughness values, which were obtained before and after in contact with Cu 2+, were 3.51 nm and 2.46 nm, respectively.

In this study, the combination of novel valinomycin doped chitosan-graphene oxide (C-GO-V) thin film and surface plasmon resonance (SPR) system for potassium ion (K + ) detection has been developed. The novel C-GO-V thin film was deposited on the gold surface using spin coating technique. The system was used to monitor SPR signal for K + in solution with and without C-GO-V thin film. The K + can be detected by measuring the SPR signal when C-GO-V thin film is exposed to K + in solution. The sensor produces a linear response for K + ion up to 100ppm with sensitivity and detection limit of 0.00948°ppm -1 and 0.001ppm, respectively. These results indicate that the C-GO-V film is high potential as a sensor element for K + that has been proved by the SPR measurement., (Copyright © 2017 Elsevier B.V. All rights reserved.)