Hypoxic Culture Conditions as a Solution for Mesenchymal Stem Cell Based Regenerative Therapy

Cell-based regenerative therapies, based on in vitro propagation of stem cells, offer tremendous hope to many individuals suffering from degenerative diseases that were previously deemed untreatable. Due to the self-renewal capacity, multilineage potential, and immunosuppressive property, mesenchymal stem cells (MSCs) are considered as an attractive source of stem cells for regenerative therapies. However, poor growth kinetics, early senescence, and genetic instability during in vitro expansion and poor engraftment after transplantation are considered to be among the major disadvantages of MSC-based regenerative therapies. A number of complex inter-and intracellular interactive signaling systems control growth, multiplication, and differentiation of MSCs in their niche. Common laboratory conditions for stem cell culture involve ambient O-2 concentration (20%) in contrast to their niche where they usually reside in 2-9% O-2. Notably, O-2 plays an important role in maintaining stem cell fate in terms of proliferation and differentiation, by regulating hypoxia-inducible factor-1 (HIF-1) mediated expression of different genes. This paper aims to describe and compare the role of normoxia (20% O-2) and hypoxia (2-9% O-2) on the biology of MSCs. Finally it is concluded that a hypoxic environment can greatly improve growth kinetics, genetic stability, and expression of chemokine receptors during in vitro expansion and eventually can increase efficiency of MSC-based regenerative therapies.Article Link: http://www.hindawi.com/journals/tswj/2013/632972

Three-loop HTLpt thermodynamics at finite temperature and chemical potential

In this proceedings we present a state-of-the-art method of calculating thermodynamic potential at finite temperature and finite chemical potential, using Hard Thermal Loop perturbation theory (HTLpt) up to next-to-next-leading-order (NNLO). The resulting thermodynamic potential enables us to evaluate different thermodynamic quantities including pressure and various quark number susceptibilities (QNS). Comparison between our analytic results for those thermodynamic quantities with the available lattice data shows a good agreement.Comment: 5 pages, 6 figures, conference proceedings of XXI DAE-BRNS HEP Symposium, IIT Guwahati, December 2014; to appear in 'Springer Proceedings in Physics Series

Site-selective lysine conjugation methods and applications towards antibody-drug conjugates

Site-selective protein modification is of significant interest in chemical biology research, with lysine residues representing a particularly challenging target. Whilst lysines are popular for bioconjugation, due to their nucleophilicity, solvent accessibility and the stability of the resultant conjugates, their high abundance means site-selectivity is very difficult to achieve. Antibody-drug conjugates (ADCs) present a powerful therapeutic application of protein modification, and have often relied extensively upon lysine bioconjugation for their synthesis. Here we discuss advances in methodologies for achieving site-selective lysine modification, particularly within the context of antibody conjugate construction, including the cysteine-to-lysine transfer (CLT) protocol which we have recently reported

Possible Detection of Causality Violation in a Non-local Scalar Model

We consider the possibility that there may be causality violation detectable at higher energies. We take a scalar nonlocal theory containing a mass scale $\Lambda$ as a model example and make a preliminary study of how the causality violation can be observed. We show how to formulate an observable whose detection would signal causality violation. We study the range of energies (relative to $\Lambda$) and couplings to which the observable can be used.Comment: Latex, 30 page

Design and Simulation of Control strategies for Voltage Source PWM Rectifier

Power Electronics is defined as branch of science, engineering and technology which deals with Power Electronics Modulators (PEM) in which efficient conversion, conditioning, processing, controlling and modulating the flow of large electric power using Solid State Power Semiconductor Device (SSPSD) in order to supply high quality power to the load which causes minimum pollution of physical characteristics of electric power with regulating stability and response characteristics of the closed loop system and its application. Diode rectified circuit and thyristor rectifiers circuit are widely used in the conventional rectifier circuit, but the problems arising during operating should not be ignored, such as, harmonic problems and low power factor. These problems may do harm to the grid, which in turn cause a series consequences, therefore, the application of such rectifier will be limited. With the continuous development of PWM technology people pay attention to the PWM rectifier gradually. The paper first analyzes the mathematical model of three-phase voltage-source PWM rectifier and then introduces double closed-loop control of voltage and current system, in which the active and reactive power can be controlled independently. PWM rectifier control system is built based on the DSP2812 after modeling and simulating in MATLAB / SIMULINK environment. The result shows that the system has the characteristic of good anti-interference performance and fast dynamic response

Analysis and Assessment of Motor Drive Speed Control through Variable Frequency Drive

Electric Motor Drive System is employed in the various industrial applications such as pumping, air blowing, cooling and compression refrigeration. The motor drive speed control can be achieved by variety of techniques, but an emerging one is Variable Frequency Drive System. The motor driven equipment on a typical industrial site accounts for approximately two thirds of the electricity consumption. Therefore, any type of measure taken to improve the efficiency of a motor system consequently can offer major energy savings. There are multiple benefits of variable frequency drive system utilizing along with speed control. For the technical and economic reliability of such integrated approach of motor with variable frequency drive, analysis and assessment is the key tool. This paper first outlines the benefits of Variable Frequency Drives (VFD) compared to classical drivers or control methods (i.e. steam/gas turbines, hydraulic coupling and Direct-On-Line operation with, for example, valve/damper control). The paper then focuses on analysis and assessment of typical variable frequency drive applications in the sugar industry and also describes a real case study, namely a VFD soft-starter application at Narmada Sugar Factory, Bharuch

Design of Resistance Spot Welding System using Integral Switching Cycle Control Technique

The process of combining metal of similar composition by heating at suitable temperature with or without pressure and application of filler material is known as Welding. Resistance Spot Welding (RSW) is defined as a process which requires simultaneous application of high electrical current and appropriate pressure over short periods in order to keep the molten material inside the weld zone. Values of these parameters are varied in function of the characteristics of the materials to be welded. The application of the electrical current carrying two copper electrodes brought in contact with the welded parts while the required pressure is applied by means of pneumatic or hydraulic systems. This paper presents a novel design of resistance welding system using Integral Switching Cycle Control Technique used for performing a welding process. The paper is discussed about two aspects. First, a brief introduction about welding, methods of welding control and electronic control used in resistance welding. Secondly, the critical factors in design of a welding process are dealt along with the principle of the welding process. Following this, the introduction to the design of control scheme employed with the basic block diagram of welding system and its functioning is presented

Quantitative assessment of people-oriented forestry in Bangladesh: A case study in the Tangail forest division

ArticleJOURNAL OF ENVIRONMENTAL MANAGEMENT. 88(1): 83-92 (2008)journal articl