28 results on '"Jabbar G"'
Search Results
2. Frequency of normative word associations in the speech of individuals at familial high-risk for schizophrenia
- Author
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Manschreck, T.C., Merrill, A.M., Jabbar, G., Chun, J., and DeLisi, L.E.
- Published
- 2012
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3. Assessment of Physico-chemical Status of Ground Water Samples of Bhoom Area of Marathwada, India.
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Mulla, Jabbar G, Pradhan, Vidya, Ubale, Millind, Hussain, Sayyed, and Farooqui, Mazahar
- Published
- 2012
4. A single-center, single-blinded, randomized, parallel-group, non-inferiority trial to compare the efficacy of a 22-gauge needle versus a 15 blade to perform an Achilles tendon tenotomy in 244 clubfeet—study protocol
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Manon Pigeolet, Jabbar Ghufran Syed, Sadia Ahmed, Muhammad Amin Chinoy, and Mansoor Ali Khan
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Clubfoot ,Global surgery ,Pediatrics ,Orthopedics ,Ponseti treatment ,Medicine (General) ,R5-920 - Abstract
Abstract Background Achilles tendon tenotomy is an integral part of the Ponseti method, aimed at correcting residual equinus and lack of dorsiflexion after correction of the adductus deformity in clubfoot. Percutaneous tenotomy using a number 15 scalpel blade is considered the gold standard, resulting in excellent results with minimal complications. The use of a large-bore needle to perform Achilles tendon tenotomies has been described in literature, but a large-scale randomized controlled trial is currently lacking. In this trial, we aim to show the non-inferiority of the needle tenotomy technique compared to the gold standard blade tenotomy technique. Methods We will randomize 244 feet into group A: needle tenotomy or group B: blade tenotomy. Randomization will be done using a block randomization with random block sizes and applying a 1:1 allocation to achieve an intervention and control group of the exact same size. Children will be evaluated at 3 weeks and 3 months post-tenotomy for primary and secondary clinical outcomes. The primary clinical outcome will be the range of dorsiflexion obtained the secondary clinical outcomes will be frequency of minor and major complications and Pirani score. The non-inferiority margin was set at 4°, and thus, the null hypothesis of inferiority of the needle technique will be rejected if the mean difference between both techniques is less than 4°. The statistical analysis will use a multi-level mixed effects linear regression model for the primary outcomes and a multi-level mixed effects logistic regression model for the secondary clinical outcomes. The physician performing the evaluations post-tenotomy will be the only one blinded to group allocation. Trial registration This trial was registered prospectively with ClinicalTrials.gov registration number: NCT04897100 on 21 May 2021.
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- 2023
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5. Temporal change of Barujari Volcano magmatic process: Inferred from petrological study of erupted products since AD 1944
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Abdul-Jabbar, G, primary, Rachmat, H, additional, and Nakagawa, M, additional
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- 2019
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6. Identification characteristics of volcanic deposits in Cimarga, Southeast Banten.
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Yekini, M A, Sitorus, F, Jabbar, G A, and Supriyanto
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- 2020
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7. A new approach to the bipolar Shilkret integral
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Jabbar Ghafil
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non-additive measure ,shilkret integral ,bipolar scales ,bi-capacity ,bipolar shilkret integral ,Mathematics ,QA1-939 - Abstract
Abstract: Capacity, also known as a non-additive measure, is an extension of the Lebesgue measure. In recent years, bi-capacity was presented as a generalization of capacity with several bipolar fuzzy integrals related to bi-capacity, one of them being the bipolar Shilkret integral. In this paper, we propose a new approach to calculating the bipolar Shilkret integral to be suitable for bipolar scales. Then, we give some main properties of this integral related to bi-capacity.
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- 2022
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8. Editorial: Energy materials based novel solar thermal applications
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Muhammad Amjad, Enio Pedone Bandarra Filho, Shafiq Ahmad, Fahid Riaz, Muhammad Abdul Qyyum, Yanwei Hu, and Jabbar Gardy
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solar PV ,nanomaterials ,AI in solar energy ,heat transfer intensification ,solar PVT ,solar thermal collector ,General Works - Published
- 2023
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9. Designing of all-optical subtractor via PC-based resonators
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Forogh Pakrai, Mohammad Soroosh, and jabbar ganji
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half-subtractor ,optical kerr effect ,photonic crystal ,resonant ring ,Electrical engineering. Electronics. Nuclear engineering ,TK1-9971 ,Applied optics. Photonics ,TA1501-1820 - Abstract
Abstract Using a photonic crystal array, an all-opticalhalf-subtractor has been designed that consists of fourresonant rings and some waveguides which connect twoinput ports to output ports. The silicon rods with a periodof 0.631 μm are arranged in the form of a square.Concerning the four working states of the device,different radii of nonlinear rods inside the resonatorshave been chosen. This issue makes the differentswitching thresholds for the rings and results in thecorrect dropping operation for optical waves. Unlike theprevious works, each bit is defined to one port, and theinput ports have equal power. The maximum rise timeand the contrast ratio of the presented circuit are 3.5 psand 8.45 dB, respectively. The fast response and smallsize are the main advantages of the presented subtractor.The obtained results demonstrates that the designeddevice has an acceptable performance which is proper foroptical applications.
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- 2022
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10. Fabrication of Two Layers Al/Cu Metal Composite by Roll Bonding Technique
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Sara Alzubaidi, Jabbar Gattmah, and Sadettin Orhan
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Roll bonding technique RBT ,Al8112/Cu composite ,Thickness reduction (R%) ,Bonding temperature (T) ,Engineering machinery, tools, and implements ,TA213-215 ,Mechanics of engineering. Applied mechanics ,TA349-359 ,Electrical engineering. Electronics. Nuclear engineering ,TK1-9971 ,Chemical engineering ,TP155-156 ,Environmental engineering ,TA170-171 - Abstract
The sheet metal of two-layer composite (Al/Cu) is considered as one of the most important products used in different engineering applications. The roll bonding technique (RBT) is an active process to fabricate the metal composite due to the occurrence of high deformation that leads to layers bonding together. In this study, Al8112 and pure Cu were selected as the metals to create a sheet composite (Al8112/Cu) by employing RBT on the basis of one cycle at various thickness reductions (R%; 45%, 50%, 55%, and 60%) and bonding temperatures (T; 300 °C, 400 °C, and 450 °C). The microstructure behaviour was examined to check the overlap bonding area for the composite layers. Vickers microhardness and tensile tests were also performed to measure the hardness, yield strength, and tensile strength. The results revealed that the R% had a strong effect on the interface bonding zone and hardness. It also had a significant effect on yield and tensile strength. However, T had a small effect on the hardness and a disparate effect on the yield and tensile strength.
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- 2022
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11. Functionalization of metallic powder for performance enhancement
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Rahul Unnikrishnan, Jabbar Gardy, Ben F. Spencer, Robin Kurinjimala, Avishek Dey, Vahid Nekouie, Sandeep Irukuvarghula, Ali Hassanpour, Christoph Eisenmenger-Sittner, John A. Francis, and Michael Preuss
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Flowability of powder ,Functionalization of powder ,Oxidation protection ,SA508 grade 3 steel ,Surface modification ,Materials of engineering and construction. Mechanics of materials ,TA401-492 - Abstract
The oxidation state and surface properties of powder particles play a major role in the final properties of powder manufactured components. In the present study, the coating of a non-stainless low alloy (SA508 Grade 3) steel powder was explored to protect it from progressive oxidation while also studying the effects on powder flowability and electrical charging. The protective coating was applied by magnetron sputtering of chromium. The surface chemistries of both as-received and Cr coated powders were studied using X-ray photo electron spectroscopy (XPS). Accelerated oxidation tests were carried out on both uncoated and Cr coated powders to study the effects of coating on oxidation resistance. Hard X-ray photoelectron spectroscopy (HAXPES) analysis was used to measure oxygen pick up near the surface, showing significant reductions for the case of the Cr coated powder. The conductivity of the powder was found to increase with Cr coating. The flowability of the powder was characterised by the tapped density, the angle of repose (AOR) and a powder rheometer, and it was found to improve with a Cr coating, which can be attributed to reduced tribo-electrical charging and reduced cohesivity of the powder particles.
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- 2022
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12. Low energy and area efficient quaternary multiplier with carbon nanotube field effect transistors
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Saeed Rahmati, Ebrahim Farshidi, and Jabbar Ganji
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carbon nano tube ,minimum power consumption ,multiplier ,quaternary logic ,Telecommunication ,TK5101-6720 ,Electronics ,TK7800-8360 - Abstract
In this study, new multiplier and adder method designs with multiplexers are proposed. The designs are based on quaternary logic and a carbon nanotube field‐effect transistor (CNTFET). The design utilizes 4 × 4 multiplier blocks. Applying specific rotational functions and unary operators to the quaternary logic reduced the power delay produced (PDP) circuit by 54% and 17.5% in the CNTFETs used in the adder block and by 98.4% and 43.62% in the transistors in the multiplier block, respectively. The proposed 4 × 4 multiplier also reduced the occupied area by 66.05% and increased the speed circuit by 55.59%. The proposed designs are simulated using HSPICE software and 32 nm technology in the Stanford Compact SPICE model for CNTFETs. The simulated results display a significant improvement in the fabrication, average power consumption, speed, and PDP compared to the current best‐performing techniques in the literature. The proposed operators and circuits are evaluated under various operating conditions, and the results demonstrate the stability of the proposed circuits.
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- 2021
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13. Photoabsorption Enhancement in Synthetic-Natural Dye-Sensitized Solar Cells Using Bilayer TiO2 Deposition and Separated Sensitization
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Roohollah Nakhaei, Alireza Razeghizadeh, Pejman Shabani, Jabbar Ganji, and Seyed Sajjad Tabatabaee
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Renewable energy sources ,TJ807-830 - Abstract
In this study, a new methodology is proposed for the cosensitization of dye-sensitized solar cells by synthetic and natural dyes to increase their optical absorption. Synthetic dyes are efficient but expensive. In contrast, natural dyes are cheap but have a low adsorption rate in competition with synthetic dyes. Therefore, the conventional cosensitization method which is based on dye mixing prevents complete adsorption of natural dyes. In this work, a bilayer deposition of TiO2 and separated sensitization of each layer by one type of dye was performed. The N719 was used as a synthetic dye and betanin, crocin, acacetin, and indigo were used as natural dyes, which are extracted from plants inexpensively. The dyes were evaluated by UV-visible and FT-IR analyses. The results showed that a broad spectrum can be achieved due to different peaks in the photoabsorption spectra of these dyes. The bottom layer was sensitized by natural dyes while the top layer was sensitized by N719. Due to the effect of temperature on dyes, a low-temperature method based on acid-assistant sintering has been used for the top layer. The results of XRD and FESEM analyses indicated that a layer with proper crystalline phase, acceptable morphology, and good porosity can be achieved in the low-temperature process by tunning the acid concentration. The electrical properties of the fabricated solar cells were investigated by EIS analysis and J-V characteristics. The results showed that charge injection and transportation were improved via the ability of the proposed approach in separated dye adsorption. An efficiency of 3.48% was provided by the proposed method which demonstrates its better performance in comparison with the cocktail and sequential methods that showed efficiencies of 1.88% and 2.29%, respectively. The results indicated that separated sensitization of each layer can improve the dye loading leading to spectral expansion.
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- 2022
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14. Smart and Multi-Functional Magnetic Nanoparticles for Cancer Treatment Applications: Clinical Challenges and Future Prospects
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Elham Aram, Masome Moeni, Roya Abedizadeh, Davood Sabour, Hamid Sadeghi-Abandansari, Jabbar Gardy, and Ali Hassanpour
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smart magnetic nanoparticles ,theranostics ,cancer ,Chemistry ,QD1-999 - Abstract
Iron oxide nanoparticle (IONPs) have become a subject of interest in various biomedical fields due to their magnetism and biocompatibility. They can be utilized as heat mediators in magnetic hyperthermia (MHT) or as contrast media in magnetic resonance imaging (MRI), and ultrasound (US). In addition, their high drug-loading capacity enabled them to be therapeutic agent transporters for malignancy treatment. Hence, smartening them allows for an intelligent controlled drug release (CDR) and targeted drug delivery (TDD). Smart magnetic nanoparticles (SMNPs) can overcome the impediments faced by classical chemo-treatment strategies, since they can be navigated and release drug via external or internal stimuli. Recently, they have been synchronized with other modalities, e.g., MRI, MHT, US, and for dual/multimodal theranostic applications in a single platform. Herein, we provide an overview of the attributes of MNPs for cancer theranostic application, fabrication procedures, surface coatings, targeting approaches, and recent advancement of SMNPs. Even though MNPs feature numerous privileges over chemotherapy agents, obstacles remain in clinical usage. This review in particular covers the clinical predicaments faced by SMNPs and future research scopes in the field of SMNPs for cancer theranostics.
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- 2022
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15. A digital-based approach for characterising spread powder layer in additive manufacturing
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Yi He, Jabbar Gardy, Ali Hassanpour, and Andrew E. Bayly
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Powder spreading ,Additive manufacturing ,Discrete element method ,Chamber pore ,Density pore ,Materials of engineering and construction. Mechanics of materials ,TA401-492 - Abstract
Assessing the quality of a spread powder layer is critical to understanding powder spreadability in additive manufacturing. However, the small layer thickness presents a great challenge for a systematic and consistent characterisation of the spread powder layer. In this study, a novel digital-based characterisation approach is proposed based on space discretization, with an emphasis on the characteristics that is important to powder-bed-based additive manufacturing. With the developed approach, the spread powder layer can be qualitatively illustrated by contour maps and quantified by statistics of packing density, surface profile and pore characteristics. For the first time, two types of pores are proposed for the spread powder layer. The density pore can identify those less populated areas while the chamber pore is able to quantify the size of empty patches observed in the spread powder bed. Applicability of this approach is demonstrated via both simulation-generated and experimentally spread powder layers. Sensitivity tests on the sampling parameters are conducted. This digital-based characterisation method is general and can be applied to both polydisperse and non-spherical particle systems, not only enriching detailed structural analysis of the spread powder layer but also allowing us to quantitatively evaluate powder spreadability in additive manufacturing.
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- 2020
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16. Seasonally anovulatory ewes fail to respond to progestogen treatment in the absence of gonadotropin stimulation
- Author
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Umberger, S.H., primary, Jabbar, G., additional, and Lewis, G.S., additional
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- 1994
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17. Melengestrol acetate and norgestomet for the induction of synchronized estrus in seasonally anovular ewes
- Author
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Jabbar, G., primary, Umberger, S. H., additional, and Lewis, G. S., additional
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- 1994
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18. NUMERICAL SIMULATION OF THERMAL BEHAVIOR AND OPTIMIZATION OF a-Si/a-Si/C-Si/a-Si/A-Si HIT SOLAR CELL AT HIGH TEMPERATURES
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Jabbar Ganji
- Subjects
heterojunction with intrinsic thin layer cell ,high temperature ,thermal behavior ,Electrical engineering. Electronics. Nuclear engineering ,TK1-9971 - Abstract
Purpose. Silicon heterostructure solar cells, particularly Heterojunction with Intrinsic Thin layer (HIT) cells, are of recommended silicon cells in recent years that are simply fabricated at low processing temperature and have high optical and temperature stability and better efficiency than homojunction solar cells. In this paper, at first a relatively accurate computational model is suggested for more precise calculation of the thermal behavior of such cells. In this model, the thermal dependency of many parameters such as mobility, thermal velocity of carriers, band gap, Urbach energy of band tails, electron affinity, relative permittivity, and effective density of states in the valence and conduction bands are considered for all semiconductor layers. The thermal behavior of HIT solar cells in the range of 25-75 °C is studied by using of this model. The effect of the thickness of different layers of HIT cell on its external parameters has been investigated in this temperature range, and finally the optimal thicknesses of HIT solar cell layers to use in wide temperature range are proposed.
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- 2017
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19. Effects of the semi die/plug angles on cold tube drawing with a fixed plug by FEM for AISI 1010 steel tube
- Author
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Sadettin Orhan, Fahrettin Öztürk, and Jabbar Gattmah
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Cold drawing ,FEM ,Residual stress ,semi die angle ,drawing stress ,Engineering (General). Civil engineering (General) ,TA1-2040 ,Chemistry ,QD1-999 - Abstract
Bu makalede, AISI 1010 çelik borunun, sabit bir mandrel ile soğuk çekme işleminin benzetimi için sonlu eleman metodu kullanılmıştır. Farklı sürtünme katsayıları için, %23 kesit daralmasında yarı kalıp/mandrel açılarının çekme gerilmesi üzerine etkileri araştırılmıştır. Sonlu elemanlar modeli, deneysel verilerle başarıyla doğrulanmıştır. Elde edilen sonuçlar, sonlu elemanlar metodu ve deneysel çalışmanın iyi bir uyum sergilediğini göstermiştir. Sonuç olarak,daha büyük boyutları nedeniyle, yarı kalıp açısının plastik deformasyona etkisi, yarı mandrel açısından daha büyüktür. 120 yarı kalıp açısı, tüm sürtünme katsayıları için en az çekme gerilmesi oluşturur. Konik sabit mandrel ile boru çekme işleminde yarı kalıp açısı 70 iken, 20 ve 40 arasındaki yarı mandrel açısı kullanılmalıdır.
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- 2017
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20. Catalytic Pyrolysis of Plastic Waste: Moving Toward Pyrolysis Based Biorefineries
- Author
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Rashid Miandad, Mohammad Rehan, Mohammad A. Barakat, Asad S. Aburiazaiza, Hizbullah Khan, Iqbal M. I. Ismail, Jeya Dhavamani, Jabbar Gardy, Ali Hassanpour, and Abdul-Sattar Nizami
- Subjects
catalytic pyrolysis ,pyrolysis based biorefineries ,natural zeolite ,plastic waste ,aromatic compounds ,modified natural zeolite ,General Works - Abstract
Pyrolysis based biorefineries have great potential to convert waste such as plastic and biomass waste into energy and other valuable products, to achieve maximum economic and environmental benefits. In this study, the catalytic pyrolysis of different types of plastics wastes (PS, PE, PP, and PET) as single or mixed in different ratios, in the presence of modified natural zeolite (NZ) catalysts, in a small pilot scale pyrolysis reactor was carried out. The NZ was modified by thermal activation (TA-NZ) at 550°C and acid activation (AA-NZ) with HNO3, to enhance its catalytic properties. The catalytic pyrolysis of PS produced a higher liquid oil (70 and 60%) than PP (40 and 54%) and PE (40 and 42%), using TA-NZ and AA-NZ catalysts, respectively. The gas chromatography-mass spectrometry (GC-MS) analysis of oil showed a mixture of aromatics, aliphatic and other hydrocarbon compounds. The TA-NZ and AA-NZ catalysts showed a different effect on the wt% of catalytic pyrolysis products and liquid oil chemical compositions, with AA-NZ showing higher catalytic activity than TA-NZ. FT-IR results showed clear peaks of aromatic compounds in all liquid oil samples with some peaks of alkanes that further confirmed the GC-MS results. The liquid oil has a high heating value (HHV) range of 41.7–44.2 MJ/kg, close to conventional diesel. Therefore, it has the potential to be used as an alternative source of energy and as transportation fuel after refining/blending with conventional fuels.
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- 2019
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21. Synthesis of Uniform Mesoporous Zeolite ZSM-5 Catalyst for Friedel-Crafts Acylation
- Author
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Heman A. Smail, Mohammad Rehan, Kafia M. Shareef, Zainab Ramli, Abdul-Sattar Nizami, and Jabbar Gardy
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ZSM-5 ,mesoporous zeolite ,Friedel-Crafts acylation ,modification of ZSM-5 ,anisole ,Chemistry ,QD1-999 - Abstract
This work highlights how the treatment of ZSM-5 (parent Zeolite Socony Mobil–5, Si/Al = 23) with different surfactant templates and alkaline solution, improved the catalytic performance in the Friedel-Crafts acylation of anisole with a propionic anhydride to obtain p-methoxypropiophenone. The modified microporous to mesoporous zeolite catalysts were characterized using different analytical techniques, including X-ray diffraction (XRD), nitrogen porosimetry, Fourier-transform infrared spectroscopy (FT-IR), temperature-programmed desorption (ammonia-TPD) and field emission scanning electron microscopy (FE-SEM) to analyze the crystallographic structure, surface acidity, surface area, porosity, morphology, and particle size. The results showed that the formed mesoporous zeolite by NaOH solution had smaller mesopores (ca. 3.7 nm) as compared to the mesoporous zeolites obtained by surfactant templates, such as, CTAB (ca. 14.9 nm), TPAOH (ca. 11.1 nm) and mixture of CTAB/TPAOH (ca. 15.2 nm). The catalytic acylation reaction was conducted in a batch glass reactor at various temperatures and the products were analyzed using off-line gas chromatography–mass spectrometry (GC-MS). It was found that the activity of treated ZSM-5 with mixed surfactant templates (CTAB/TPAOH) exhibited enhanced selectivity towards the main product (p-methoxypropiophenone) by a factor 1.7 or higher than unmodified ZSM-5 due to its increased surface area by 1.5 times and enhanced acid sites.
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- 2019
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22. ChemInform Abstract: 4‐NITROPHENYLAZOACETIC ACID AND ITS DERIVATIVES
- Author
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FERNANDES, P. S., primary, NADKARNY, V. V., additional, JABBAR, G. A., additional, and JANI, R. P., additional
- Published
- 1976
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23. ChemInform Abstract: NEW SYNTHESIS OF 6-NITRO-4-HYDROXY AND 8-NITRO-4-HYDROXY CINNOLINES
- Author
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FERNANDES, P. S., primary, NADKARNY, V. V., additional, JABBAR, G. A., additional, and JANI, R. P., additional
- Published
- 1975
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24. BASAL GANGLIA VASCULAR MINERALIZATION IN AIDS
- Author
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Perl, D. P., primary, Good, P. F., additional, and Jabbar, G., additional
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- 1989
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25. Correlates to the variable effects of cannabis in young adults: a preliminary study
- Author
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Camera Ariella A, Tomaselli Veronica, Fleming Jerry, Jabbar Gul A, Trachtenberg Melissa, Galvez-Buccollini Juan A, Proal Ashley C, Rosenthal Richard N, and DeLisi Lynn E
- Subjects
Public aspects of medicine ,RA1-1270 - Abstract
Abstract Background Cannabis use can frequently have adverse affects in those that use it and these can be amplified by various characteristics of an individual, from demographic and environmental variations to familial predisposition for mental illnesses. Methods The current study of 100 individuals, who were cannabis users during their adolescence and may still be users, was a survey of the self perceived effects of cannabis and their correlates. A reliable family member was also interviewed for determination of family history of various major mental illnesses and substance use. Results As many as 40% of cannabis users had paranoid feelings (suspiciousness) when using cannabis, although the most frequent effect was feeling relaxed (46%). Having a familial background for mental illnesses such as depression or schizophrenia did not determine the effects of cannabis nor its pattern of use, although the number of subjects with such a history was small. An age at which an individual began using cannabis did have an effect on how heavily it was used and the heavier the cannabis use, the more likely the individual was also to have had psychotic symptoms after use. There were no sex differences in effects of cannabis. These results are tempered by the reliance on self-report for many of the variables ascertained. Conclusion Cannabis can frequently have negative effects in its users, which can be amplified by certain demographic and/or psychosocial factors. Thus, users with a specific profile may be at a higher risk of unpleasant effects from cannabis use and caution should be noted when cannabis is administered to young people for medicinal purposes.
- Published
- 2012
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26. Field-Induced Modulated State in the Ferromagnet PrPtAl.
- Author
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O'Neill CD, Abdul-Jabbar G, Wermeille D, Bourges P, Krüger F, and Huxley AD
- Abstract
The theory of quantum order-by-disorder (QOBD) explains the formation of modulated magnetic states at the boundary between ferromagnetism and paramagnetism in zero field. PrPtAl has been argued to provide an archetype for this. Here, we report the phase diagram in magnetic field, applied along both the easy a axis and hard b axis. For field aligned to the b axis, we find that the magnetic transition temperatures are suppressed and at low temperature there is a single modulated fan state, separating an easy a axis ferromagnetic state from a field polarized state. This fan state is well explained with the QOBD theory in the presence of anisotropy and field. Experimental evidence supporting the QOBD explanation is provided by the large increase in the T^{2} coefficient of the resistivity and direct detection of enhanced magnetic fluctuations with inelastic neutron scattering, across the field range spanned by the fan state. This shows that the QOBD mechanism can explain field induced modulated states that persist to very low temperature.
- Published
- 2021
- Full Text
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27. Altered language network activity in young people at familial high-risk for schizophrenia.
- Author
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Thermenos HW, Whitfield-Gabrieli S, Seidman LJ, Kuperberg G, Juelich RJ, Divatia S, Riley C, Jabbar GA, Shenton ME, Kubicki M, Manschreck T, Keshavan MS, and DeLisi LE
- Subjects
- Adult, Analysis of Variance, Brain blood supply, Female, Humans, Image Processing, Computer-Assisted, Language Tests, Linear Models, Male, Neuropsychological Tests, Oxygen blood, Reaction Time, Schizophrenia physiopathology, Semantics, Young Adult, Brain physiopathology, Brain Mapping, Language, Schizophrenia pathology, Schizophrenic Psychology
- Abstract
Background: Abnormalities in language and language neural circuitry are observed in schizophrenia (SZ). Similar, but less pronounced language deficits are also seen in young first-degree relatives of people with SZ, who are at higher familial risk (FHR) for the disorder than the general population. The neural underpinnings of these deficits in people with FHR are unclear., Methods: Participants were 43 people with FHR and 32 comparable controls. fMRI scans were collected while participants viewed associated and unrelated word pairs, and performed a lexical decision task. fMRI analyses conducted in SPM8 examined group differences in the modulation of hemodynamic activity by semantic association., Results: There were no group differences in demographics, IQ or behavioral semantic priming, but FHR participants had more schizotypal traits than controls. Controls exhibited the expected suppression of hemodynamic activity to associated versus unrelated word pairs. Compared to controls, FHR participants showed an opposite pattern of hemodynamic modulation to associated versus unrelated word pairs, in the left inferior frontal gyrus (IFG), right superior and middle temporal gyrus (STG) and the left cerebellum. Group differences in activation were significant, FWE-corrected for multiple comparisons (p<0.05). Activity within the IFG during the unrelated condition predicted schizotypal symptoms in FHR participants., Conclusions: FHR for SZ is associated with abnormally increased neural activity to semantic associates within an inferior frontal/temporal network. This might increase the risk of developing unusual ideas, perceptions and disorganized language that characterize schizotypal traits, potentially predicting which individuals are at greater risk to develop a psychotic disorder., (© 2013.)
- Published
- 2013
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28. Decreased axial diffusivity within language connections: a possible biomarker of schizophrenia risk.
- Author
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Kubicki M, Shenton ME, Maciejewski PK, Pelavin PE, Hawley KJ, Ballinger T, Swisher T, Jabbar GA, Thermenos HW, Keshavan MS, Seidman LJ, and Delisi LE
- Subjects
- Adolescent, Adult, Anisotropy, Female, Humans, Image Processing, Computer-Assisted, Male, Young Adult, Cerebral Cortex pathology, Diffusion Tensor Imaging methods, Language Disorders etiology, Language Disorders pathology, Nerve Fibers, Myelinated pathology, Schizophrenia complications
- Abstract
Siblings of patients diagnosed with schizophrenia are at elevated risk for developing this disorder. The nature of such risk associated with brain abnormalities, and whether such abnormalities are similar to those observed in schizophrenia, remain unclear. Deficits in language processing are frequently reported in increased risk populations. Interestingly, white matter pathology involving fronto-temporal language pathways, including arcuate fasciculus (AF), uncinate fasciculus (UF), and inferior occipitofrontal fasciculus (IOFF), are frequently reported in schizophrenia. In this study, high spatial and directional resolution diffusion MRI data was obtained on a 3T magnet from 33 subjects with increased familial risk for developing schizophrenia, and 28 control subjects. Diffusion tractography was performed to measure white matter integrity within AF, UF, and IOFF. To understand these abnormalities, Fractional Anisotropy (FA, a measure of tract integrity) and Trace (a measure of overall diffusion), were combined with more specific measures of axial diffusivity (AX, a putative measure of axonal integrity) and radial diffusivity (RD, a putative measure of myelin integrity). Results revealed a significant decrease in Trace within IOFF, and a significant decrease in AX in all tracts. FA and RD anomalies, frequently reported in schizophrenia, were not observed. Moreover, AX group effect was modulated by age, with increased risk subjects demonstrating a deviation from normal maturation trajectory. Findings suggest that familial risk for schizophrenia may be associated with abnormalities in axonal rather than myelin integrity, and possibly associated with disruptions in normal brain maturation. AX should be considered a possible biomarker of risk for developing schizophrenia., (Copyright © 2013 Elsevier B.V. All rights reserved.)
- Published
- 2013
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