Influence of Post-Implantation Annealing Parameters on the Focused Ion Beam Directed Nucleation of InAs Quantum Dots

M. Mehta,D. Reuter,M. Kamruddin,A. K. Tyagi,A. D. Wieck 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2015 NANO Vol.10 No.4

We present the effect of post-implantation annealing conditions on the structural and optical quality of InAs quantum dots (QDs) grown by combination of focused ion beam (FIB) and molecular beam epitaxy (MBE) approach. A FIB of Ga+ ion was employed to pattern a homogeneously GaAs buffer layers and then, an in situ annealing step followed by InAs deposition was performed. Three different post-implantation annealing conditions were tested and under well-optimized conditions, a dislocation and defect-free InAs QDs growth on FIB patterned surface was successfully achieved. Furthermore, using photoluminescence (PL) study, we demonstrate that our best sample shows almost similar optical quality as MBE grown QDs on unimplanted GaAs surface. The patterning technique described here can presumably be applied to systems other than InAs/GaAs and highly interesting for site-controlled nucleation of QDs that finds its potential applications in nanooptoelectronic devices.

Design, optimization and pharmacokinetics of novel prolonged gastroretentive drug delivery system of quetiapine fumarate

Dharmik M. Mehta,Punit B. Parejiya,Hetal K. Patel,Palak J. Trivedi,Disha D. Suthar,Pragna K. Shelat 한국약제학회 2016 Journal of Pharmaceutical Investigation Vol.46 No.5

Present study attempts to overcome pH-dependent solubility, a limitation for oral delivery of poorly soluble BCS class-II drugs. A pH independent, patient compliant, dual working gastroretentive drug delivery system of model drug quetiapine fumarate (QF) was fabricated by unique combination approach of mucoadhesion and floating. Bilayer tablets comprising floating adhesive layer (FL) and matrix layer (ML) was systematically optimized by applying 32 full factorial experimental designs. Selected variables for FL: Polyox 303WSR (X1FL) and alginate beads (X2FL), and for ML: HPMC K100M (X1ML) and fumaric acid (X2ML) were studied against responses for FL: floating lag time (R1FL), total floating time (R2FL) and adhesion force (R3FL) and for ML: percentage drug released at 2 h—Q2h (R1ML), 8 h—Q8h (R2ML), and 18 h—Q18h (R3ML), respectively. Optimized batch (OP) showed floating lag time (6.5 h), total floating time (14 h), adhesion force (0.82 N) and Q18h ([90 %). Pharmacokinetic study of OP and immediate release market product demonstrated improved bioavailability (*12 % higher AUC0–?) of OP. In a nutshell, developed drug delivery system can be fabricated as a platform for QF and similar BCS class-II drugs with pH dependent solubility.

Non-stationary quasi-periodic pulsations in solar and stellar flares

Nakariakov, V M,Kolotkov, D Y,Kupriyanova, E G,Mehta, T,Pugh, C E,Lee, D-H,Broomhall, A-M IOP 2019 Plasma physics and controlled fusion Vol.61 No.1

<P>Often the enhanced electromagnetic radiation generated in solar and stellar flares shows a pronounced (quasi)-oscillatory pattern—quasi-periodic pulsations (QPP), with characteristic periods ranging from a fraction of a second to several tens of minutes. We review recent advances in the empirical study of QPP in solar and stellar flares, addressing the intrinsic non-stationarity of the signal, i.e. the variation of its amplitude, period or phase with time. This non-stationarity could form a basis for a classification of QPP, necessary for revealing specific physical mechanisms responsible for their appearance. We could identify two possible classes of QPP, decaying harmonic oscillations, and trains of symmetric triangular pulsations. Apparent similarities between QPP and irregular geomagnetic pulsations Pi offer a promising avenue for the knowledge transfer in both analytical techniques and theory. Attention is also paid to the effect of the flare trend on the detection and analysis of QPP.</P>

Rewiring of Genetic Networks in Response to DNA Damage

Bandyopadhyay, S.,Mehta, M.,Kuo, D.,Sung, M.-K.,Chuang, R.,Jaehnig, E. J.,Bodenmiller, B.,Licon, K.,Copeland, W.,Shales, M.,Fiedler, D.,Dutkowski, J.,Guenole, A.,van Attikum, H.,Shokat, K. M.,Kolodner American Association for the Advancement of Scienc 2010 Science Vol.330 No.6009

<P>Although cellular behaviors are dynamic, the networks that govern these behaviors have been mapped primarily as static snapshots. Using an approach called differential epistasis mapping, we have discovered widespread changes in genetic interaction among yeast kinases, phosphatases, and transcription factors as the cell responds to DNA damage. Differential interactions uncover many gene functions that go undetected in static conditions. They are very effective at identifying DNA repair pathways, highlighting new damage-dependent roles for the Slt2 kinase, Pph3 phosphatase, and histone variant Htz1. The data also reveal that protein complexes are generally stable in response to perturbation, but the functional relations between these complexes are substantially reorganized. Differential networks chart a new type of genetic landscape that is invaluable for mapping cellular responses to stimuli.</P>

The Energy-Efficient Algorithm for a Sensor Network

Mehta, S.,Oh, S.-M.,Kim, J.-H. SPRINGER-VERLAG 2005 Lecture Notes in Computer Science Vol.3391 No.-

Analysis of unreinforced masonry (URM) walls and evaluation of retrofitting schemes for URM structures

Mehta, Sanjay,Saadeghvaziri, M.A. Techno-Press 1998 Structural Engineering and Mechanics, An Int'l Jou Vol.6 No.7

An overview of an analytical model to predict mortar joint failure in unreinforced masonry (URM) structures is presented. The validity of the model is established by comparison with experimental results at element level as well as structure level. This model is then used to study the behavior of URM walls and two commonly used retrofitting schemes. Finally, effectiveness of the two retrofitting schemes in increasing strength and stiffness of existing URM walls is discussed.

Epidemiological Insights from 1,652 Patients with Spinal Tuberculosis Managed at a Single Center: A Retrospective Review of 5-Year Data

Garg Bhavuk,Mehta Nishank,Mukherjee Rudra Narayan,Swamy Arun M.,Siamwala Burhan S.,Malik Garima 대한척추외과학회 2022 Asian Spine Journal Vol.16 No.2

Study Design: Retrospective cohort. Purpose: To report the demographic characteristics, clinico-radiological presentation, laboratory findings, and outcomes of “middle-path” treatment in patients with spinal tuberculosis from a single public healthcare facility in a developing country. Overview of Literature: Tuberculosis is a global health problem that is endemic in developing countries and undergoing resurgence in developed ones. Spinal tuberculosis can cause disabling back pain, progressive deformity, and neurological involvement. However, there is a lack of large-scale epidemiological studies quantifying the size and severity of the problem of spinal tuberculosis. Methods: Hospital records of spinal tuberculosis patients treated at a single center over a period of 5 years were retrospectively reviewed. A diagnosis of spinal tuberculosis was based on standard clinical, radiological, microbiological, and histopathological evidence. Patients were treated in accordance with the “middle-path” regimen; surgery was reserved for selective indications. Results: A total of 1,652 patients were included. Their median age was 32.4 years, with 53% being male. Axial pain (98%) was the most common presenting symptom; 19% of patients had neurological deficit. Lumbar spine (37%) was the most common site of involvement, with a paradiscal pattern (82%) of involvement predominating. Multi-level involvement was seen in 19% of patients; skip lesions were noted in 2.8%. Transpedicular biopsy was performed in 667 patients; at least one tissue test was diagnostic of tuberculosis in 65% of patients. Forty-four patients had drug resistance to rifampicin. Surgery was required in 10.5% of patients. The “middle-path” regimen was associated with high compliance and significant improvements in pain (Visual Analog Scale score) and function (36-Item Short Form Health Survey). Conclusions: Our findings confirm the widespread prevalence of spinal tuberculosis and describe various epidemiological characteristics of a large sample of spinal tuberculosis patients. Adoption of the “middle-path” regimen is associated with high compliance and favorable outcomes in spinal tuberculosis.

FEEDING OF BYPASS PROTEIN TO CROSS BRED COWS IN INDIA ON STRAW BASED RATION

Kunju, P.J.G.,Mehta, A.K.,Garg, M.R. Asian Australasian Association of Animal Productio 1992 Animal Bioscience Vol.5 No.1

Feeding of bypass protein to lactating animals have been suggested by many research scientists as a way to increase the nutrient supply at the intestinal level thereby enhance animal production in ruminant animals. A feeding trial with a formulated bypass protein feed on straw based ration was carried out by using lactating cross bred cows at the stage of 4th month of their lactation. Bypass protein feed was fed at 5 different levels. Urea Molasses Block was used as a nitrogen source to the rumen microflora. In order to reduce the heat increment straw intake was restricted to all the animals. Urea Molasses Block intake was noticed varying in proportion with the bypass protein feed intake. Milk production was observed increasing in accordance with the level of bypass protein feed intake. However, the maximum response was noticed in cows that were fed 3 kg bypass protein feed. The nutrient availability at this stage was below the NRC (1988) requirements. Other remarkable finding was that the cows maintained the persistency of milk production even after 3rd month of lactation when the ambient temperature was $40^{\circ}C$.

Laser Doppler Anemometer Measurements in Complex Three-Dimensional Recirculating Flowfields

H. W. Shin,J. M. Mehta 대한기계학회 1990 KSME/JSME THERMAL and FLUID Engineering Conference Vol.2 No.1

Software-Based Hybrid Perfusion SPECT/CT Provides Diagnostic Accuracy When Other Pulmonary Embolism Imaging Is Indeterminate

Nishant Kumar,Karen Xie,Winnie Mar,Thomas M. Anderson,Benjamin Carney,Nikhil Mehta,Roberto Machado,Michael J. Blend,Yang Lu 대한핵의학회 2015 핵의학 분자영상 Vol.49 No.4

Purpose To investigate the diagnostic performance of perfusion single-photon emission computed tomography/computed tomography (Q-SPECT/CT) in patients suspected to have pulmonary embolism (PE) but with indeterminate computed tomographic pulmonary angiography (CTPA) or planar ventilation/perfusion (V/Q) scans. Methods This retrospective study included two groups of patients. Group I consisted of 49 patients with nondiagnostic CTPA. These 49 patients underwent subsequent V/Q scans. Further Q-SPECTs were obtained in patients with indeterminate planar images and fused with existing CTPA. Group II consisted of 182 non-CTPA patients with indeterminate V/Q scans. These 182 patients underwent further Q-SPECT and separate noncontrast low-dose CT chest. Fusion Q-SPECT/ CT scans were obtained through FDA-approved software and interpreted according to published criteria as positive, negative, or indeterminate for PE. Upon retrospective analyses, the final diagnosis was made using composite reference standards including all available clinical and imaging information for at least 6-month follow-up. Results In group I patients, 1 was positive, 24 were negative, and another 24 (49 %, 24/49) were indeterminate. In the subsequent 24 Q-SPECT/CTPAs, 4 were positive, 19 were negative, and 1 was indeterminate (4.2 %, 1/24). In group II patients, 9 (4.9 %, 9/182) were indeterminate, 33 were positive, and 140 were negative. The combined nondiagnostic rate for Q-SPECT/CT was only 4.9 % (10/ 206). There was six false-negative and one false-positive Q-SPECT/CT examinations. The sensitivity, specificity, and positive and negative predictive value of Q-SPECT/ CT were 85.7 % (36/42), 99.4 % (153/154), 97.3 % (36/ 37) and 96.2 % (153/159), respectively. Conclusions Q-SPECT/CT improves the diagnostic rate with promising accuracy in diagnosing PE that yields a satisfactory clinical verdict, especially when the CTPA and planar V/Q scan are indeterminate.