Electron conduction in fe-doped polystyrene films

The DC electrical conductivity of pure and Fe³⁺-doped polystyrene films has been studied at various bias field strengths in the temperature range 304–392K. Doped films showed increased conductivity compared with undoped films up to 0.5% dopant concentration; beyond this concentration there was a decrease in the conductivity. The increase in conductivity for lower doping concentrations (0.25% and 0.5%) is attributed to the formation of charge transfer complexes. The decrease in the electrical conductivity and the increase in the activation energy at more than 0.5% dopant concentration is due to the formation of molecular aggregates. For undoped films the activation energies in the low temperature region were found to be higher than those at higher temperatures. Also, with increasing bias field strength, the activation energies showed a decrease at all temperatures studied. It is suggested, on the basis of the magnitudes of the activation energies, that electronic conduction is the dominant charge transport mechanism both at low and high temperatures.     

Exclusion of atrial thrombus by transesophageal echocardiography does not preclude embolism after cardioversion of atrial fibrillation. A multicenter study

BACKGROUND: Transesophageal echocardiography (TEE) has been used recently to detect atrial thrombi before cardioversion of atrial arrhythmias. It has been assumed that embolic events after cardioversion result from embolism of preexisting atrial thrombi that are accurately detected by TEE. This study examined the clinical and echocardiographic findings in patients with embolism after cardioversion of atrial fibrillation despite exclusion of atrial thrombi by TEE. METHODS AND RESULTS: Clinical and echocardiographic data in 17 patients with embolic events after TEE-guided electrical (n = 16) or pharmacological (n = 1) cardioversion were analyzed. All 17 patients had nonvalvular atrial fibrillation, including four patients with lone atrial fibrillation. TEE before cardioversion showed left atrial spontaneous echo contrast in five patients and did not show atrial thrombus in any patient. Cardioversion resulted in return to sinus rhythm without immediate complication in all patients. Thirteen patients had cerebral embolic events and four patients had peripheral embolism occurring 2 hours to 7 days after cardioversion. None of the patients were therapeutically anticoagulated at the time of embolism. New or increased left atrial spontaneous echo contrast was detected in four of the five patients undergoing repeat TEE after cardioversion including one patient with a new left atrial appendage thrombus. CONCLUSIONS: Embolism may occur after cardioversion of atrial fibrillation in inadequately anticoagulated patients despite apparent exclusion of preexisting atrial thrombus by TEE. These findings suggest de novo atrial thrombosis after cardioversion or imperfect sensitivity of TEE for atrial thrombi and suggest that screening by TEE does not obviate the requirement for anticoagulant therapy at the time of and after cardioversion. A randomized clinical trial is needed to compare conventional anticoagulant management with a TEE-guided strategy including anticoagulation after cardioversion.     

A comparative study of the thermal discharge behaviour of cellulose diacetate and cellulose triacetate films

The thermal discharge behaviour of cellulose diacetate (CA2) (39% acetyl content) and cellulose triacetate (CA3) (44% acetyl content) films was studied at different polarizing temperatures and fields. Cellulose diacetate exhibited two peaks, one at low temperatures and the other at high temperatures, whereas cellulose triacetate exhibited only one peak. The origin of these peaks in CA2 is attributed to dipolar orientation and space charge polarization respectively, while the only peak in CA3 is due to space charge polarization. The difference in thermal discharge behaviour of CA2 and CA3 is attributed to the difference in acetyl contents of the two acetates.     

Restorative proctocolectomy with end to end pouch-anal anastomosis in patients over the age of fifty

This study was to examine whether 'fit' patients over the age of 50 who require elective surgery for ulcerative colitis are suitable candidates for restorative proctocolectomy, providing that they are continent before operation and that the anal sphincter is preserved in its entirety without stripping of the mucosa or endoanal anastomosis. Between 1986 and 1991, 18 patients 50 to 66 years old (median 55 years: nine men) underwent restorative proctocolectomy with end to end ileoanal anastomosis without mucosal stripping (12 quadruplicated (W), four duplicated (J), two no reservoir). The results were compared 12 (range three to 24) months later with those of 18 matched patients who were less than 50 years of age (median 34 years). In patients over 50, median resting anal pressure was 88 (range 44-131) cm water before and 80 (47-138) cm water after the operation (NS). In patients under 50, median resting anal pressure was 76 (51-128) cm water before and 77 (36-137) cm water after operation (NS). Resting anal pressure in older patients did not differ significantly from that in younger patients either before or after the operation. Both sensory and reflex anal functions were preserved as well after operation in the older patients as in the younger ones. The clinical results in patients over 50 were slightly inferior to the results for the younger patients, but the difference was small and not significant. Hence age alone is not a contraindication to restorative surgery provided that the anal sphincter is preserved in its entirety.     

Flocculation properties of polyacrylamide grafted carboxymethyl guar gum (CMG-g-PAM) synthesised by conventional and microwave assisted method

A novel polymeric flocculant based on polyacrylamide grafted carboxymethyl guar gum (CMG-g-PAM) has been synthesised by grafting polyacrylamide chains onto CMG backbone using conventional redox grafting and microwave assisted grafting methods. Under optimum grafting conditions, 82% and 96% grafting efficiencies have been observed in case of conventional and microwave assisted methods respectively. The optimum sample has been characterized using viscometry, spectroscopic analysis, elemental analysis, molecular weight and radius of gyration determination. The flocculation characteristics of grafted and ungrafted polysaccharides have been evaluated in kaolin suspension, municipal sewage wastewater and decolourization efficiency of a dye solution (methylene blue). It is evident from results that CMG-g-PAM synthesised by microwave assisted grafting method is showing best flocculation characteristics.     

Effect of temperature and sanitizers on the survival of feline calicivirus, Escherichia coli, and F-specific coliphage MS2 on leafy salad vegetables

We conducted a series of experiments to compare the survival of Escherichia coli, feline calicivirus, and F-specific coliphage MS2 on lettuce and cabbage with and without disinfection. Inoculated produce was held at 4, 25, or 37 degrees C for 21 days or was treated with different concentrations of sodium bicarbonate, chlorine bleach, peroxyacetic acid, or hydrogen peroxide. Survival was measured by the decimal reduction value (time to 90% reduction in titer) and the change in log titers of the test organisms. A stronger correlation of survival measures was observed between feline calicivirus and MS2 than between E. coli and either of the viral agents at 25 and 37 degrees C. The maximum time to detection limit for MS2 at all temperatures was 9 days, whereas feline calicivirus was detected for a maximum of 14 days at 4 degrees C. In contrast, E. coli was detectable for 21 days at 4 and 25 degrees C and for 14 days at 37 degrees C. Significant increases in E. coli titer occurred within the first 5 days, but virus titers decreased steadily throughout the experiments. E. coli was also highly susceptible to all disinfectants except 1% sodium bicarbonate and 50 ppm chlorine bleach, whereas the viruses were resistant to all four disinfectants.     

Quantification of Phospholipids Classes in Human Milk

Phospholipids are integral constituents of the milk fat globule membranes and they play a central role in infants’ immune and inflammatory responses. A methodology employing liquid chromatography coupled with evaporative light scattering detector has been optimized and validated to quantify the major phospholipids classes in human milk. Phospholipids were extracted using chloroform and methanol and separated on C18 column. Repeatability, intermediate reproducibility, and recovery values were calculated and a large sample set of human milk analyzed. In human milk, phospholipid classes were quantified at concentrations of 0.6 mg/100 g for phosphatidylinositol; 4.2 mg/100 g for phosphatidylethanolamine, 0.4 mg/100 g for phosphatidylserine, 2.8 mg/100 g for phosphatidylcholine, and 4.6 mg/100 g for sphingomyelin. Their relative standard deviation of repeatability and intermediate reproducibility values ranging between 0.8 and 13.4 % and between 2.4 and 25.7 %, respectively. The recovery values ranged between 67 and 112 %. Finally, the validated method was used to quantify phospholipid classes in human milk collected from 50 volunteers 4 weeks postpartum providing absolute content of these lipids in a relatively large cohort. The average content of total phospholipids was 23.8 mg/100 g that corresponds to an estimated mean intake of 140 mg phospholipids/day in a 4-week old infant when exclusively breast-fed.