Micellization and Clouding Behavior of EO–PO Block Copolymer in Aqueous Salt Solutions

Aqueous solution properties of polyethylene oxide–block-polypropylene oxide–block-polyethylene oxide TBP [(PEO)₁₀₃(PPO)₃₉(PEO)₁₀₃] were studied in the presence of sodium salts with different anions (NaI, NaBr, NaCl, NaF, Na₂SO₄, Na₃PO₄) to investigate unimer-to-micelle transition [critical micelle concentration (CMC), critical micellization temperature (CMT)], micelle size and the phase separation (cloud point). This TBP, due to its very hydrophilic (80% PEO) nature does not form micelles at ambient temperatures. Micellization can be induced much below its CMT in water on addition of sodium salts having different anions. Analytical methods viz. fluorescence, FTIR and dynamic light scattering (DLS) were used to monitor the salt-induced micellization. The hydration of respective anion and resultant contribution to its salting-out effect was found to be the governing factor in promoting micellization. The presence of salt decreases the CMC, CMT and phase separation temperature. The salts affect the aggregation process in agreement with an order mentioned in Hofmeister series.     

Effect of moisture on the oxidation behavior of ZrB2

Oxidation studies of ZrB₂ were performed under wet air and dry air conditions at 1200°C, 1400°C, and 1500°C for 1, 4, and 10 h. Compared to dry air, the presence of water vapor was found to enhance the oxidation kinetics by a factor of 7 to 30, depending on the temperature. Thermodynamic calculations suggested that water vapor promoted the formation of additional volatile species such as boric acid (HBO₂), in addition to boria (B₂O₃) produced in dry air, which increased the evaporation rate of B₂O₃. Compared to dry air, the presence of water vapor leads to more rapid evaporation of boria and the transition from parabolic oxidation kinetic behavior (ie, rate controlled by diffusion through boria) to linear (ie, underlying ZrB₂ is directly exposed to the oxidizing environment) at shorter times and lower temperatures.     

Key issues in the microchemical systems-based methanol fuel processor: Energy density,thermal integration,and heat loss mechanisms

Microreactor technology is a promising approach in harnessing the high energy density of hydrocarbons and is being used to produce hydrogen-rich gases by reforming of methanol and other liquid hydrocarbons. However, on-demand H₂ generation for miniature proton exchange membrane fuel cell (PEMFC) systems has been a bottleneck problem, which has limited the development and demonstration of the PEMFC for high-performance portable power. A number of crucial challenges exist for the realization of practical portable fuel processors. Among these, the management of heat in a compact format is perhaps the most crucial challenge for portable fuel processors. In this study, a silicon microreactor-based catalytic methanol steam reforming reactor was designed, fabricated, and demonstrated in the context of complete thermal integration to understand this critical issue and develop a knowledge base required to rationally design and integrate the microchemical components of a fuel processor. Detailed thermal and reaction experiments were carried out to demonstrate the potential of microreactor-based on-demand H₂ generation. Based on thermal characterization experiments, the heat loss mechanisms and effective convective heat coefficients from the planar microreactor structure were determined and suggestions were made for scale up and implementation of packaging schemes to reduce different modes of heat losses.     

Automatic room information retrieval and classification from floor plan using linear regression model

International Journal on Document Analysis and Recognition (IJDAR) - The automatic creation of a repository of the building’s floor plan helps a lot to the architects to reuse them. The basic...     

Safety analysis of intermittent hemodialysis in patients with continuous flow left ventricular assist devices

Dialysis centers adopt a cautious approach when it comes to performing intermittent hemodialysis (HD) on patients with continuous flow (CF) left ventricular assist devices (LVADs) because of the potential for volume flux‐related complications and absence of pulsatile blood pressure for monitoring. Many patients have to remain hospitalized because of the inability of the dialysis centers to accept them for outpatient dialysis. In this study, the effect of HD was observed in such patients. Between June 2009 and October 2012, 139 patients received LVADs, of which 10 patients (7%) required intermittent HD postoperatively. The mean age of the patients was 53 ± 14 years and 90% were men. A total of 281 dialysis sessions were administered amounting to 1025 hours of dialysis. The mean systolic blood pressure monitored with Doppler device was 97 ± 18 mmHg. Dialysis durations averaged 218 ± 18 minutes. Mean blood flow rate was 334 ± 38 cc/min, and 2.6 ± 1.1 L was ultrafiltrated during each session. Only 15 (5.3%) sessions were interrupted or terminated in six patients. The reasons for termination were symptomatic hypotension—6 (2.1%), asymptomatic hypotension—3 (1%), ventricular tachycardia—1 (0.36%), dialysis machine malfunction—2 (0.7%), low phosphorus—2 (0.7%), and abdominal cramps—1 (0.36%). Volume expansion was necessary on three occasions. Low‐flow device alarms were registered during two (0.71%) sessions. The results showed no serious adverse effects or deaths.     

An efficient one pot synthesis of water-dispersible calix[4]arene polyhydrazide protected gold nanoparticles--a "turn off" fluorescent sensor for Hg[II] ions

In the present study, we report the synthesis of aqueous stable gold nanoparticles by using calix[4]arene polyhydrazide (CPH) as both reducing and capping agents. The calix[4]arene polyhydrazide reduced gold nanoparticles (CPH-AuNps) were characterized by UV/Vis, particle size analyzer (PSA) and transmission electron mictroscopy (TEM). The records confirmed high stability of CPH-AuNps in aqueous solution over a long period of time and even at varied pH. Additionally, CPH-AuNps have been investigated for its application as "Turn Off" fluorescent sensor for Hg[II]. A concentration of Hg[II] in the limit of 10 nM to 10 microM can be detected based on fluorescence quenching of the CPH-AuNPs and it was also concluded from the spectroscopic data that CPH-AuNPs possess excellent selectivity to Hg[II] over several metal ions like Pb[II], Cu[II], Cd[II], Mn[II], Zn[II] and Ni[II].     

Effect of chronic hypovitaminosis A on water metabolism in the weanling rat

To study water imbalance reported to occur in vitamin A deficiency, chronic hypovitaminosis A was produced in 7-week old rats by feeding deficient or adequate vitamin A (12 or 256 mug/kg body weight/day, respectively) for a comparison period of 6 weeks. In the case of the deficient rats, these were partially depleted of their vitamin A stores prior to feeding the 12 mug intake. At the termination of the comparison period, the deficient rats exhibited elevated cerebrospinal fluid pressure and lower plasma and liver vitamin A concentrations. Based upon kinetics of a single intrajugular injection of 3H2O and 14C-inulin, total body water, extracellular water and renal clearances were lower in vitamin A deficient rats. However, when these criteria were expressed on a body weight basis, there were no significant differences. The turnover of total body water was reduced in the hypovitaminotic A rats. The results are discussed in terms of an inhibitory effect of vitamin A deficiency on growth.