THE GROWTH , PROPERTIES AND APPLICATIONS OF Si1-xGex ALLOYS

Iyer, S. S. 대한전자공학회 1989 ICVC : International Conference on VLSI and CAD Vol.1 No.1

Novel low temperature epitaxial growth techniques such as Molecular Beam Epitaxy and Low Temperature Chemical Vapor Deposition permit the use of pseudomorphic Si_(1-x)Ge_x alloys in silicon technology. The smaller bandgap of these alloys allows for a variety of novel band engineered structures that promise to significantly enhance silicon based technology. In this brief review, we discuss the growth and properties of pseudomorphic Si_(1-x)Ge_x structures, their properties and then focus on their applications, especially the Si_(1-x)Ge_x base heterojunction bipolar transistor (HBT).

Implications of small modular reactors for climate change mitigation

Iyer, G.,Hultman, N.,Fetter, S.,Kim, S.H. IPC Science and Technology Press ; Elsevier Scienc 2014 ENERGY ECONOMICS Vol.45 No.-

Achieving climate policy targets will require large-scale deployment of low-carbon energy technologies, including nuclear power. The small modular reactor (SMR) is viewed as a possible solution to the problems of energy security as well as climate change. In this paper, we use an integrated assessment model (IAM) to investigate the evolution of a global energy portfolio with SMRs under a stringent climate policy. Technology selection in the model is based on costs; we use results from previous expert elicitation studies of SMR costs. We find that the costs of achieving a 2<SUP>o</SUP>C target are lower with SMRs than without. The costs are higher when large reactors do not compete for market share compared to a world in which they can compete freely. When both SMRs and large reactors compete for market share, reduction in mitigation cost is achieved only under advanced assumptions about SMR technology costs and future cost improvements. While the availability of SMRs could lower mitigation costs by a moderate amount, actual realization of these benefits would depend on the rapid up-scaling of SMRs in the near term. Such rapid deployment could be limited by several social, institutional and behavioral obstacles.

Isolation, Screening, and Selection of an L-glutaminase Producer from Soil and Media Optimization Using a Statistical Approach

Iyer Padma,Rekha Singhal 한국생물공학회 2010 Biotechnology and Bioprocess Engineering Vol.15 No.6

A culture isolated from garden soil was found to be a promising L-glutaminase producer. Biochemical identification tests and 16S rRNA sequencing identified this isolate to be Klebsiella oxytoca. Subsequently, media optimization using one-factor-at-a-time approach and response surface methodology was undertaken. A face centered central composite design was employed to investigate the interactive effects of four variables, viz. concentrations of maltose, yeast extract, beef extract, and ammonium acetate on glutaminase production. Almost all factors had significant interactive effects on glutaminase production. A medium containing (g/L): maltose, 23.31; yeast extract, 20.0; beef extract, 20.01; ammonium acetate, 10.0; mannitol, 10.0;KH2PO4, 0.4; Na2SO4, 0.4; and MgCl2, 0.4 was optimum for glutaminase production. The applied methodology was validated using this optimized media and enzyme activity of 458.91 ± 9.49 U/L and specific activity of 0.441 ± 0.04U/mg protein after 42 h of incubation at 33oC were obtained.

Technical efficiency analysis of container terminals in India

Iyer K. Chandrasekhar,Nanyam V.P.S. Nihar 한국해운물류학회 2021 The Asian journal of shipping and Logistics Vol.37 No.1

Despite the number of studies on the efficiency of container ports, most studies are of developed nations, and very few are of developing nations, such as India. Indian container ports are very critical due to their location advantage and their ability to handle transhipment traffic. There is a need to understand their performance at the micro-level, specifically the terminal level rather than that of the whole port. This paper focuses on the analysis of the technical efficiency of 26 container terminals in India using a data envelopment analysis approach for the years 2015–2018 and interprets it with respect to location advantage, administrative control and private control of terminal operations. The research explores the Malmquist index which measures productivity changes over a period of time and deconstructs them into two components, namely efficiency change, referred to as catch-up, and frontier shift. This study enabled the ranking of these terminals in terms of their performances. The relative efficiency of container terminals on the west coast of India is found to be better than that of the east coast of India, and the efficiency of container terminals operating under major ports is on a declining path when compared with that of minor ports. The private participation has also not seen similar productivity changes across all container terminals. Among the seven high performing container terminals identified through the analysis provided, the terminal at Tuticorin emerged as the most consistent one in terms of relative efficiency and growth in total factor productivity. The dominant factor influencing the efficiency of a terminal is found to be the size of the terminal, offering the advantages of economies of scale.

Diffusion of low-carbon technologies and the feasibility of long-term climate targets

Iyer, G.,Hultman, N.,Eom, J.,McJeon, H.,Patel, P.,Clarke, L. American Elsevier 2015 TECHNOLOGICAL FORECASTING AND SOCIAL CHANGE Vol.90 No.1

Stabilizing the global climate will require large-scale global deployment of low-carbon technologies. Even in the presence of aggressive climate policies, however, the diffusion of such technologies may be limited by several institutional, behavioral, and social factors. In this paper, we review the literature on the sources of such diffusion constraints, and explore the potential implications of such constraints based on the GCAM integrated assessment model. Our analysis highlights that factors that limit technology deployment may have sizeable impacts on the feasibility and mitigation costs of achieving stringent stabilization targets. And such impacts are greatly amplified with major delays in serious climate policies. The results generally indicate that constraints on the expansions of CCS and renewables are more costly than those on nuclear or bioenergy, and jointly constraining these technologies leaves some scenarios infeasible.

Keratinocyte Migration in a Three-Dimensional In Vitro Wound Healing Model Co-Cultured with Fibroblasts

Kritika Iyer,Zhuo Chen,Teja Ganapa,Benjamin M. Wu,Bill Tawil,Chase S. Linsley 한국조직공학과 재생의학회 2018 조직공학과 재생의학 Vol.15 No.6

BACKGROUND: Because three-dimensional (3D) models more closely mimic native tissues, one of the goals of 3D in vitro tissue models is to aid in the development and toxicity screening of new drug therapies. In this study, a 3D skin wound healing model comprising of a collagen type I construct with fibrin-filled defects was developed. METHODS: Optical imaging was used to measure keratinocyte migration in the presence of fibroblasts over 7 days onto the fibrin-filled defects. Additionally, cell viability and growth of fibroblasts and keratinocytes was measured using the alamarBlue assay and changes in the mechanical stiffness of the 3D construct was monitored using compressive indentation testing. RESULTS: Keratinocyte migration rate was significantly increased in the presence of fibroblasts with the cells reaching the center of the defect as early as day 3 in the co-culture constructs compared to day 7 for the control keratinocyte monoculture constructs. Additionally, constructs with the greatest rate of keratinocyte migration had reduced cell growth. When fibroblasts were cultured alone in the wound healing construct, there was a 1.3 to 3.4-fold increase in cell growth and a 1.2 to 1.4-fold increase in cell growth for keratinocyte monocultures. However, co-culture constructs exhibited no significant growth over 7 days. Finally, mechanical testing showed that fibroblasts and keratinocytes had varying effects on matrix stiffness with fibroblasts degrading the constructs while keratinocytes increased the construct’s stiffness. CONCLUSION: This 3D in vitro wound healing model is a step towards developing a mimetic construct that recapitulates the complex microenvironment of healing wounds and could aid in the early studies of novel therapeutics that promote migration and proliferation of epithelial cells.

COVID-19: an update on diagnostic and therapeutic approaches

Mahalaxmi Iyer,Kaavya Jayaramayya,Mohana Devi Subramaniam,Soo Bin Lee,Ahmed Abdal Dayem,Ssang-Goo Cho,Balachandar Vellingiri 생화학분자생물학회 2020 BMB Reports Vol.53 No.4

The unexpected pandemic set off by the novel coronavirus 2019 (COVID-19) has caused severe panic among people worldwide. COVID-19 has created havoc, and scientists and physicians are urged to test the efficiency and safety of drugs used to treat this disease. In such a pandemic situation, various steps have been taken by the government to control and prevent the Severe Acute Respiratory Syndrome coronavirus 2 (SARSCoV- 2). This pandemic situation has forced scientists to rework strategies to combat infectious diseases through drugs, treatment, and control measures. COVID-19 treatment requires both limiting viral multiplication and neutralizing tissue damage induced by an inappropriate immune reaction. Currently, various diagnostic kits to test for COVID-19 are available, and repurposing therapeutics for COVID-19 has shown to be clinically effective. As the global demand for diagnostics and therapeutics continues to rise, it is essential to rapidly develop various algorithms to successfully identify and contain the virus. This review discusses the updates on specimens/samples, recent efficient diagnostics, and therapeutic approaches to control the disease and repurposed drugs mainly focusing on chloroquine/hydroxychloroquine and convalescent plasma (CP). More research is required for further understanding of the influence of diagnostics and therapeutic approaches to develop vaccines and drugs for COVID-19.

A Review of Complications and Outcomes following Vertebral Column Resection in Adults

Sravisht Iyer,Venu M. Nemani,Han Jo Kim 대한척추외과학회 2016 Asian Spine Journal Vol.10 No.3

The correction of rigid spinal deformities in adult patients can require a three-column osteotomy (pedicle subtraction osteotomy [PSO] or vertebral column resection [VCR]) to obtain spinal balance. Unfortunately, the existing adult deformity literature frequently reports the outcomes and complications of these procedures together even though VCR is a more extensive procedure with potentially higher rates of complications. We sought to address this shortcoming and provide clinicians with an overview of the existing literature regarding VCR in adult patients. The goals of this review are: to determine the rate of overall and neurologic complications following VCR, the rate of complications with VCR compared to PSO, and the impact of VCR on clinical and radiographic outcomes. An electronic literature search was used to identify studies reporting outcomes or complications following VCR in adult patients. Raw data on patient demographics, case information, radiographic outcomes, complications and clinical outcomes were extracted. Data were pooled to report a rate of overall complications and neurologic complications. A pooled relative risk of complications following PSO vs. VCR was also calculated. Eleven retrospective studies (Level IV) met our inclusion criteria. The overall rate of complications was 69.2%. The reoperation rate was 9.6%. The rate of neurologic complications was 13.3% (range, 6.3% to 15.8%) with most cases being transient. The rate of permanent neurologic deficits was 2.0%. We found a significantly higher rate of all complications with VCR compared to PSO (relative risk, 1.36; 95% confidence interval, 1.24–1.49; p <0.001). All studies reporting clinical outcomes showed significant improvements in functional outcome postoperatively.

Job Release Control in Semiconductor Wafer Fabrication

Appa Iyer Sivakumar,Chao Qi,Hiap Keong Tan,Sip Khean Lieu 대한산업공학회 2003 Industrial Engineeering & Management Systems Vol.2 No.2

Production of Glutaminase (E.C. 3.2.1.5) from Zygosaccharomyces rouxii in Solid-State Fermentation and Modeling the Growth of Z. rouxii Therein

( Padma Iyer ),( Rekha S. Singhal ) 한국미생물 · 생명공학회 2010 Journal of microbiology and biotechnology Vol.20 No.4