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41.
Hydrogels composed of etherificated sodium alginate (ESA), sodium acrylic acid (NaAA), and poly (vinyl alcohol) (PVA) were synthesized by aqueous solution polymerization. The effects of reaction variables such as terminal pH, ions, and ionic strength on hydrogel swelling ratio (SR) were determined and compared. SR was influenced strongly by pH and ionic strength. SR increased with increasing pH but tended to decrease with PVA content. At a given ionic strength, SR of ESA/NaAA/PVA hydrogel was dependent on the valence of anion; SR was higher in multivalent anion salt solution than in monovalent anion salt solution, i.e., SRK2SO4 > SRKCl and SRNa2SO4 > SRNaCl. The swelling kinetic of the hydrogels showed Fickian kinetic diffusion in acidic media and non‐Fickian behavior in alkaline media. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 相似文献
42.
V Sundaram AN Hanna L Koneru HA Newman JM Falko 《Canadian Metallurgical Quarterly》1997,82(10):3421-3424
Hypothyroidism is frequently associated with hypercholesterolemia and an increased risk for atherosclerosis, whereas hyperthyroidism is known to precipitate angina or myocardial infarction in patients with underlying coronary heart disease. We have shown previously that L-T4 functions as an antioxidant in vitro and inhibits low density lipoprotein (LDL) oxidation in a dose-dependent fashion. The present study was designed to evaluate the changes in LDL oxidation in subjects with hypothyroidism and hyperthyroidism. Fasting blood samples for LDL oxidation analyses, lipoprotein determinations, and thyroid function tests were collected at baseline and after the patients were rendered euthyroid. The lag phase (mean +/- SEM hours) of the Cu+2-catalyzed LDL oxidation in the hypothyroid state and the subsequent euthyroid states were 4 +/- 0.0.65 and 14 +/- 0.68 h, respectively (P < 0.05). The lag phase during the hyperthyroid phase was 6 +/- 0.55 h, and that during the euthyroid phase was 12 +/- 0.66 h (P < 0.05). The total and LDL cholesterol levels were higher in hypothyroidism than in euthyroidism and were lower in hyperthyroidism than in the euthyroid state. We conclude that LDL has more susceptibility to oxidation in both the hypothyroid and hyperthyroid states. Thus, the enhanced LDL oxidation may play a role in the cardiac disease process in both hypothyroidism and hyperthyroidism. 相似文献
43.
Sundaram Vickram Karunakaran Rohini Subramanian Srinivasan David Nancy Veenakumari Kumar Archana Krishnan Anbarasu Palanivelu Jeyanthi Sundaram Thanigaivel Govindarajan Gulothungan Nanmaran Rajendiran Padmalayam Sadanandan Srikumar 《International journal of molecular sciences》2021,22(4)
Zinc (Zn), the second-most necessary trace element, is abundant in the human body. The human body lacks the capacity to store Zn; hence, the dietary intake of Zn is essential for various functions and metabolism. The uptake of Zn during its transport through the body is important for proper development of the three major accessory sex glands: the testis, epididymis, and prostate. It plays key roles in the initial stages of germ cell development and spermatogenesis, sperm cell development and maturation, ejaculation, liquefaction, the binding of spermatozoa and prostasomes, capacitation, and fertilization. The prostate releases more Zn into the seminal plasma during ejaculation, and it plays a significant role in sperm release and motility. During the maternal, labor, perinatal, and neonatal periods, the part of Zn is vital. The average dietary intake of Zn is in the range of 8–12 mg/day in developing countries during the maternal period. Globally, the dietary intake of Zn varies for pregnant and lactating mothers, but the average Zn intake is in the range of 9.6–11.2 mg/day. The absence of Zn and the consequences of this have been discussed using critical evidence. The events and functions of Zn related to successful fertilization have been summarized in detail. Briefly, our current review emphasizes the role of Zn at each stage of human reproduction, from the spermatogenesis process to childbirth. The role of Zn and its supplementation in in vitro fertilization (IVF) opens opportunities for future studies on reproductive biology. 相似文献
44.
An experimental investigation has been carried out with aa point focusing dish reflector of 12 square meters aperture area,exposed to the average direct normal irradiations of 810 W/m2.This work focuses on enhancinge the energy and exergy efficiencies of the cavity receiver by minimizing the temperature difference between the wall and heat transfer fluids.Two heat transfer fluids Water and SiC + water nano fluid have been prepared from 50 nm particle size and 1% of volume fraction,and experimented separately for the flow rates of 0.2 lpm to 0.6 lpm with an interval of 0.1 lpm.The enhanced thermal conductivity of nano fluid is 0.800115 W/mK with the keff/kb ratio of 1.1759 determined by using the Koo and Kleinstreuer correlation.The maximum attained energy and exergy efficiencies are 29.14% and 24.82% for water,and 32.91% and 39.83% for SiC+water nano fluid.The nano fluid exhibits enhanced energy and exergy efficiency of 12.94% and 60.48% than that of water at the flow rate of 0.5 lpm.The result shows that the system with SiC+Water produces higher exergy efficiency as compared to energy efficiency;in the case ofwater alone,the energy efficiency is higher than exergy efficiency. 相似文献
45.
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47.
Current vs. time (I−t) measurements were performed on Ta2O5-based devices. Charge build-up at the Ta2O5/SiO2 interface was used to explain the transient. The interfacial charge density was calculated from the I−t curve and the maximum was found to be 398 nC cm-2 and 317 nC cm-2 for Al/Ta2O5/Si and Al/Ta2O5/SiO2/Si capacitors respectively. The value for MTOS was comparable with the value obtained by quasi-static measurements. 相似文献
48.
John S. McCloy Jarrod V. Crum S. K. Sundaram Ryan Slaugh Paul P. Woskov 《Journal of Infrared, Millimeter and Terahertz Waves》2011,32(11):1337-1349
Millimeter wave (MMW) radiometry can be used for simultaneous measurement of emissivity and temperature of materials under
extreme environments such as in slagging coal gasifiers, where sensors have been identified as a key enabling technology need
for process optimization. We present a dual-channel MMW heterodyne radiometer with active interferometric capability that
allows simultaneous measurements of sample temperature, emissivity, and flow dynamics. Interferometric capability at 137 GHz
is supplied via a probe signal originating from a local oscillator allowing monitoring of sample dynamics such as volume expansion
and thickness change. This capability has been used to monitor characteristic behavior between refractories and slag such
as slag infiltration, slag melting, viscous flow, foaming, and crucible corrosion by the molten slag. These results show the
promise of the MMW system for extracting process parameters from operating slagging coal gasifiers, providing valuable information
for process efficiency, control, and increased productivity. 相似文献
49.
P. Bhama Iyer S. Sreenivasan P. K. Chidambareswaran N. B. Patil V. Sundaram 《应用聚合物科学杂志》1991,42(6):1751-1757
In the present investigation, we have made a systematic study of the induced crystallization in never-dried cotton fiber, by allowing it to desiccate under different conditions of humidity and temperature. The resulting structural changes have been followed using x-ray diffraction and infrared absorption techniques. A slow rate of drying coupled with a high temperature was more conducive for maximum crystallization. Analysis of the effect of temperature on the induced crystallization showed possible existence of a thermal transition in cellulose around 30°C. The induced crystallization brought about by slow drying as well as those produced using intercrystalline swelling agents, have been shown to be resulting from a proper channelization of the interfibrillar mobility existing in the never-dried fibers. 相似文献
50.
K. B. Sundaram S. S. Seshan V. H. Desai S. M. Arora 《Journal of Materials Science: Materials in Electronics》1992,3(1):26-28
HighT
c superconductor materials of yttrium barium copper oxide (YBCO) have been etched by a new electrochemical technique. In this technique, acids like hydrochloric, nitric and phosphoric have been used as an electrolyte and etching has been achieved with acid dilutions as high as 1:200 with water. It is observed that rapid and controlled etching is possible by this technique. 相似文献