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51.
Alyson J. Turner Smitha Nair Zhen Lai Chieh‐Min Cheng Surita R. Bhatia 《应用聚合物科学杂志》2011,122(2):1358-1363
Micrometer‐sized particles were formed by controlled aggregation of carboxylated polystyrene colloidal spheres having a mean diameter of about 200 nm with a commercial cationic coagulant. To identify the parameters governing the size and structure of the aggregates, the aggregate size distribution was studied over a period of time with dynamic light scattering. The effect of the particle concentration, pH, and ionic strength on the aggregation behavior was investigated. The coagulant concentration used for present studies was 5 parts per hundred on the basis of the polystyrene particles and the particle concentrations used were 10–15%. The particle size distribution for the latex suspensions was also investigated with a 10% aluminum sulfate [Al2(SO4)3·14H2O] solution as a model coagulant. With the commercial coagulant, aggregation was found to be slower at lower pH than at neutral pH. At pH 6, the particles started to aggregate within minutes and form aggregates of about 1000 nm. We expected that lowering the pH would reduce interparticle repulsive forces and enhance the collision efficiency. However, at a lower pH of 2, the aggregation process slowed down. Increasing the ionic strength at neutral pH led to a broader aggregate size distribution, and the population of larger aggregates increased. The suspensions with the model coagulant showed similar behavior. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011 相似文献
52.
Iatrogenic hypernatremia in hemodialysis patients: A result of erroneous online conductivity monitor and conductivity meter reading 下载免费PDF全文
Chamberlain I. Obialo Smitha John Khalid Bashir 《Hemodialysis international. International Symposium on Home Hemodialysis》2017,21(4):E73-E75
Hyponatremia is common in chronic kidney disease and in end stage kidney disease (ESKD) but hypernatremia is infrequent in ESKD. The incidence of hypernatremia is higher in ambulatory peritoneal dialysis (PD) than in hemodialysis (HD) patients. In PD patients it is often a result of excessive ultrafiltration but in HD it is often a result of dialysate composition errors. Dialysate composition errors can inadvertently cause either hyponatremia or hypernatremia. We present two cases of symptomatic hypernatremia which manifested as increased thirst, excessive weight gain and worsening hypertension in HD patients. The hypernatremia was caused by a combination of errors in online conductivity reading and a faulty hand held conductivity meter. Symptoms were relieved in both patients after replacement of the dialysis machine. 相似文献
53.
The release of hemoglobin from hydrogel matrices of polyethylene glycol (PEG), polyvinyl alcohol (PVA), and crosslinked polyacrylamide (PAM) was investigated in phosphate‐buffered saline (PBS, pH 7.4) as a release medium. The hemoglobin was loaded onto hyrogels by swelling them in hemoglobin solution and the effect of composition of the hydrogel on the amount of hemoglobin loaded was observed. The effects of experimental parameters such as varying concentrations of PEG, PVA, PAM, and crosslinking agent in the feed mixture, pH of the release medium, and the presence of salts were investigated on the release dynamics of the hemoglobin. The release results were analyzed on the basis of the kinetic data, and the kinetic parameters such as the diffusional exponent (n) and diffusion constant (D) were evaluated. From the kinetic parameters data an attempt was made to explore the nature of the mechanism of the hemoglobin release process. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 104–113, 2002 相似文献
54.
M. R. Resmi K. Smitha T. N. Arunagiri T. Pradeep 《Fullerenes, Nanotubes and Carbon Nanostructures》2013,21(2):123-146
Abstract Photochemical reactions of M(CO)6 (M = W, Mo) with C60 in solution yield η:2-complexes of M(CO)5 with C60. The complexes have been characterised by IR, UV/VIS, NMR and DSC. They do not show any orientational ordering down to 12 K and all the infrared bandwidths remain the same down to this temperature. The complexes can be decomposed thermally or photochemically yielding metal fullerides, which show characteristic reduction in peak width in the variable temperature IR spectra due to orientational ordering. Transitions are manifested in calorimetric studies also. Metal → C60 charge-transfer is observed in IR and XPS. A high temperature IR study of the C60-W(CO)5 complex reveals sequential elimination of the carbonyls yielding MC60. The study shows that carbonyl complexes can be used as precursors to make transition metal fullerides. 相似文献
55.
Ancy Smitha Alex Vijendra Kumar R. S. Rajeev N. Supriya S. K. Manu 《Journal of Adhesion Science and Technology》2013,27(13):1496-1513
Hydroxyl-terminated poly(dimethylsiloxane) cured by a mixture of methyl tris (methyl ethyl ketoxime) silane and 3-aminopropyl triethoxy silane system is known for satisfactory mechanical properties and chemical resistance. The effect of nanoclay on this poly(dimethyl siloxane) (PDMS) system is explored in this study. Organically modified clay (montmorillonite) nanocomposites of PDMS were processed by solution blending followed by cross linking. The effect of nanoclay content on the mechanical, barrier, thermal and dynamic mechanical properties of the nanocomposites were investigated in detail. X-ray diffraction studies reveal exfoliated nature of the nanoclay layers in the composites. The mechanical properties, such as tensile strength and elongation at break of PDMS, improved substantially on reinforcement with nanoclay. The maximum enhancement in properties occurred at a nanoclay content of 2-3%. Cross-link density increased with increase in nanoclay concentration up to 3% and decreased with further addition. The barrier properties were not significantly altered by the incorporation of nanoclay. Initial decomposition temperatures marginally increased at lower loading levels of nanoclay, whereas a reverse trend is observed at higher loadings. The glass transition temperature remains practically the same for all the compositions. The study demonstrates that nanoclay addition is an effective method for improving the properties of PDMS. 相似文献
56.
Outer approximation algorithm with physical domain reduction for computer‐aided molecular and separation process design 下载免费PDF全文
Smitha Gopinath George Jackson Amparo Galindo Claire S. Adjiman 《American Institute of Chemical Engineers》2016,62(9):3484-3504
Integrated approaches to the design of separation systems based on computer‐aided molecular and process design (CAMPD) can yield an optimal solvent structure and process conditions. The underlying design problem, however, is a challenging mixed integer nonlinear problem, prone to convergence failure as a result of the strong and nonlinear interactions between solvent and process. To facilitate the solution of this problem, a modified outer‐approximation (OA) algorithm is proposed. Tests that remove infeasible regions from both the process and molecular domains are embedded within the OA framework. Four tests are developed to remove subdomains where constraints on phase behavior that are implicit in process models or explicit process (design) constraints are violated. The algorithm is applied to three case studies relating to the separation of methane and carbon dioxide at high pressure. The process model is highly nonlinear, and includes mass and energy balances as well as phase equilibrium relations and physical property models based on a group‐contribution version of the statistical associating fluid theory (SAFT‐γ Mie) and on the GC+ group contribution method for some pure component properties. A fully automated implementation of the proposed approach is found to converge successfully to a local solution in 30 problem instances. The results highlight the extent to which optimal solvent and process conditions are interrelated and dependent on process specifications and constraints. The robustness of the CAMPD algorithm makes it possible to adopt higher‐fidelity nonlinear models in molecular and process design. © 2016 The Authors AIChE Journal published by Wiley Periodicals, Inc. on behalf of American Institute of Chemical Engineers AIChE J, 62: 3484–3504, 2016 相似文献
57.
Puthucheri Smitha Isha Singh Mohd Najim Ravi Panwar Dharmendra Singh Vijaya Agarwala Ghanshyam Das Varma 《Journal of Materials Science: Materials in Electronics》2016,27(8):7731-7737
Stealth applications now emphasise on development of efficient Radar Absorbing Materials of light weight, less coating thickness, broad bandwidth of absorption along with cost effective raw materials and manufacturing techniques. Therefore, in this paper an attempt has been made to develop such an efficient cost effective radar absorbing material which possesses broad band absorption with less coating thickness. Unconventionality of acquiring impedance match for a double layer absorber of nanostructured nickel ferrite (NF) with reasonably good dielectric properties and its cation substituted counterpart, nickel zinc ferrite (NZF) with enhanced magnetic properties has been thoroughly investigated for radar wave absorption for very low coating thickness. Complex permittivity and permeability of NF and NZF with crystallite sizes of 10.0 and 16.0 nm, respectively, are measured and used as the data bases. The microwave absorption properties of the ferrites are correlated with their size, morphology, permittivity, permeability, thickness and bandwidth of absorption. Multilayering has been performed using the optimization through Genetic Algorithm in order to attain suitable impedance matching layer for minimum reflection loss (RL) at lower thickness. The results indicate an enhancement in the absorption with RL value of ?45.0 dB for a moderately low coating thickness of 1.72 mm. Single layers NF, NZF and multilayer NF–NZF are fabricated over the aluminium sheets and the results are experimentally verified. 相似文献
58.
In textile reinforced concrete (TRC), the yarns of the textiles are inherently wavy due to the manufacturing process. In most structural applications, this leads to delayed activation of textiles during loading and affects the composite performance negatively. In this context, the paper reports on the significance of mechanically prestressing or stretching the textiles before casting the TRC towards enhancing its load-carrying ability, which has been assessed by comparing the responses of specimens with textiles placed by manual and mechanical stretching. Studies were carried out to determine the uniaxial tensile behaviour of TRC with two types of alkali-resistant glass textiles, woven and bonded and their combinations. TRC with mechanically-stretched woven textile exhibits better performance compared to that of the manually stretched textile, in terms of load-carrying ability though the elongation at failure could be compromised for specimens with bonded textiles. Mechanically stretched textile lead to pronounced strain hardening behaviour, enhancement in the stress at first cracking and stress at peak, which also increase as the number of layers increases. The failure of TRC with manually stretched textile occurs with the pullout of the textile from the matrix contrasting with the rupture of textile when mechanically stretched. X-ray tomography images of the internal structure of TRC further revealed that there is less frictional bond loss and debonding of textile from the matrix for mechanically stretched textile. 相似文献
59.
Asymmetrically Encapsulated Vertical ITO/MoS2/Cu2O Photodetector with Ultrahigh Sensitivity 下载免费PDF全文
Sangeeth Kallatt Smitha Nair Kausik Majumdar 《Small (Weinheim an der Bergstrasse, Germany)》2018,14(3)
Strong light absorption, coupled with moderate carrier transport properties, makes 2D layered transition metal dichalcogenide semiconductors promising candidates for low intensity photodetection applications. However, the performance of these devices is severely bottlenecked by slow response with persistent photocurrent due to long lived charge trapping, and nonreliable characteristics due to undesirable ambience and substrate effects. Here ultrahigh specific detectivity (D*) of 3.2 × 1014 Jones and responsivity (R) of 5.77 × 104 A W?1 are demonstrated at an optical power density (Pop) of 0.26 W m?2 and external bias (Vext) of ?0.5 V in an indium tin oxide/MoS2/copper oxide/Au vertical multi‐heterojunction photodetector exhibiting small carrier transit time. The active MoS2 layer being encapsulated by carrier collection layers allows us to achieve repeatable characteristics over large number of cycles with negligible trap assisted persistent photocurrent. A large D* > 1014 Jones at zero external bias is also achieved due to the built‐in field of the asymmetric photodetector. Benchmarking the performance against existing reports in literature shows a viable pathway for achieving reliable and highly sensitive photodetectors for ultralow intensity photodetection applications. 相似文献
60.
Luciana Sartore Chiara Pasini Stefano Pandini Kamol Dey Marco Ferrari Stefano Taboni Harley H. L. Chan Jason Townson Sowmya Viswanathan Smitha Mathews Ralph W. Gilbert Jonathan C. Irish Federica Re Piero Nicolai Domenico Russo 《International journal of molecular sciences》2022,23(9)
A great promise for tissue engineering is represented by scaffolds that host stem cells during proliferation and differentiation and simultaneously replace damaged tissue while maintaining the main vital functions. In this paper, a novel process was adopted to develop composite scaffolds with a core-shell structure for bone tissue regeneration, in which the core has the main function of temporary mechanical support, and the shell enhances biocompatibility and provides bioactive properties. An interconnected porous core was safely obtained, avoiding solvents or other chemical issues, by blending poly(lactic acid), poly(ε-caprolactone) and leachable superabsorbent polymer particles. After particle leaching in water, the core was grafted with a gelatin/chitosan hydrogel shell to create a cell-friendly bioactive environment within its pores. The physicochemical, morphological, and mechanical characterization of the hybrid structure and of its component materials was carried out by means of infrared spectroscopy, thermogravimetric analysis, scanning electron microscopy, and mechanical testing under different loading conditions. These hybrid polymer devices were found to closely mimic both the morphology and the stiffness of bones. In addition, in vitro studies showed that the core-shell scaffolds are efficiently seeded by human mesenchymal stromal cells, which remain viable, proliferate, and are capable of differentiating towards the osteogenic phenotype if adequately stimulated. 相似文献