Plasma modification on a Nafion membrane for direct methanol fuel cell applications

This research focuses on Nafion modification using plasma techniques for direct methanol fuel cell applications. The results indicated the both argon (Ar) and carbon tetrafluoride (CF₄) plasma treatments modified the Nafion surface substantially without altering the bulk properties. The Nafion surface exposed to CF₄ plasma resulted in a more hydrophobic layer and an even lower MeOH permeability than the Ar-treated membrane. The plasma operating conditions using CF₄ were optimized by utilizing an experimental design. The minimum MeOH permeability was reduced by 74%. The conductivity was 1–2×10^-3 S/cm throughout the entire experimental range. Suppressed MeOH permeability can be achieved while maintaining the proton conductivity at a satisfactory level by adjusting the plasma operating conditions.     

A novel dielectric drying method of sea cucumber

The sea cucumber autolyses readily so it must be dehydrated for preservation. Traditional drying methods of sea cucumber need very long time and have adverse effect on quality. Hence, a novel microwave freeze drying technique was developed to dry sea cucumber. Because microwave heating is a function of dielectric properties of the material in microwave field, dielectric properties of sea cucumber were determined. As expected, the dielectric loss factor of sea cucumbers was very low in frozen state, and several pretreatments (nanoscale calcium carbonate impregnation and vacuum impregnation, salt impregnation, etc.) were analysed to improve the dielectric properties of sea cucumber. Vacuum impregnation with nanoscale calcium carbonate combined with microwave freeze drying was found to be an efficient drying method for sea cucumber by anova (P < 0.01). Compared with microwave freeze drying method without any treatments, this drying method could reduce the drying time by up to two hours.     

Studies on different combined microwave drying of carrot pieces

Three different combined microwave (MW) drying methods were compared, namely microwave‐assisted vacuum drying (MWVD), microwave‐assisted freeze drying (MWFD), microwave‐enhanced spouted bed drying (MWSD), in terms of drying rate, drying uniformity, product colour, rehydration ratio, retention of β‐carotene and vitamin C, and energy consumption. The drying rate of MWVD and MWSD were much faster than that of MWFD. The largest drying rate was obtained in MWSD with 3.5 W g^?1. In general, the colour of MWSD products was very uniform. Rehydration ratio of MWFD carrot pieces was almost the same as the freeze‐dried (FD) products and better than MWVD and MWSD products. In addition, the highest retention of carotene and vitamin C was observed in MWFD carrot pieces. No significant differences were observed in carotene and vitamin C between MWVD and MWSD products. However, the energy consumption in MWFD was the highest.     

Effects of carbon nanotubes on rheological behavior in cellulose solution dissolved at low temperature

Multi-walled carbon nanotubes (MWNTs) were dispersed, for the first time, in cellulose solution in 9.5 wt% NaOH/4.5 wt% thiourea aqueous system pre-cooled to −5 °C. Dynamic light scattering and transmission electron microscopy results revealed a relatively strong interaction existed between MWNTs and the cellulose macromolecules, leading to a good dispersion of MWNTs in the cellulose solution. Their rheological behaviors, especially the sol-gel transition were investigated by using the advanced rheological expanded system on the basis of Winter and Chambon theory. The gel point and gel concentration of the cellulose/MWNTs solution system were determined, indicating a regularly rheological behavior. The data of loss tangent and relaxation exponent (n) indicated an enhancement in the viscoelasticity of the MWNTs/cellulose system. The results from scaling law before and beyond the sol-gel transition in the MWNTs/cellulose system confirmed that the cluster formation and alteration of the gelation structure occurred at the gel point. Interestingly, the n values calculated by both the Winter and Chambon theory and scaling law were coincident only at relatively low temperature. The predicted gel strength values of the MWNTs/cellulose system were significantly larger than the pure cellulose solution, suggesting a relatively high strength, supported by the mechanical strength of the cellulose/MWNTs material.     

Light scattering study on the dynamic behaviour of cellulose inclusion complex in LiOH/urea aqueous solution

In our previous study, the rapid dissolution of cellulose in alkali/urea aqueous solution at low temperature induced by a dynamic self-assembly process has been demonstrated [1]. The cellulose solution was meta-stable, and its stability could be influenced by system fluctuations (temperature, concentration or time). In the present work, cellulose dissolved in 4.6wt% LiOH/15.0wt% urea aqueous solution pre-cooled to −12 °C was studied by means of dynamic light scattering (DLS). The results revealed that cellulose existed as single inclusion complexes (ICs) associated with LiOH and urea hydrate which could surround the ICs at their surface. And the ICs were stiff, as revealed by results from transmission electron microscopy (TEM) and light scattering (LS). When there was a system fluctuation, the self-association of cellulose with each other took place, resulted from the destruction of the urea shell, and leading to the aggregation of the ICs. For that reason, the ICs stability could be evaluated by the aggregation behaviour. In our findings, the hydrodynamic radius (R_h,app) for the cellulose dispersion in dilute solution shifted to higher values with an increase of the temperature, the concentration or the storage time, indicating an IC aggregation phenomenon.     

Oral sildenafil in the treatment of erectile dysfunction. Sildenafil Study Group

BACKGROUND: Sildenafil is a potent inhibitor of cyclic guanosine monophosphate hydrolysis [corrected] in the corpus cavernosum and therefore increases the penile response to sexual stimulation. We evaluated the efficacy and safety of sildenafil, administered as needed in two sequential double-blind studies of men with erectile dysfunction of organic, psychogenic, and mixed causes. METHODS: In a 24-week dose-response study, 532 men were treated with oral sildenafil (25, 50, or 100 mg) or placebo. In a 12-week, flexible dose-escalation study, 329 different men were treated with sildenafil or placebo, with dose escalation to 100 mg based on efficacy and tolerance. After this dose-escalation study, 225 of the 329 men entered a 32-week, open-label extension study. We assessed efficacy according to the International Index of Erectile Function, a patient log, and a global-efficacy question. RESULTS: In the dose-response study, increasing doses of sildenafil were associated with improved erectile function (P values for increases in scores for questions about achieving and maintaining erections were <0.001). For the men receiving 100 mg of sildenafil, the mean score for the question about achieving erections was 100 percent higher after treatment than at base line (4.0 vs. 2.0 of a possible score of 5). In the last four weeks of treatment in the dose-escalation study, 69 percent of all attempts at sexual intercourse were successful for the men receiving sildenafil, as compared with 22 percent for those receiving placebo (P<0.001). The mean numbers of successful attempts per month were 5.9 for the men receiving sildenafil and 1.5 for those receiving placebo (P<0.001). Headache, flushing, and dyspepsia were the most common adverse effects in the dose-escalation study, occurring in 6 percent to 18 percent of the men. Ninety-two percent of the men completed the 32-week extension study. CONCLUSIONS: Oral sildenafil is an effective, well-tolerated treatment for men with erectile dysfunction.     

The transition from the d- to s-state due to thermal fluctuationfor high-Tc superconductors as an evidence from the microwavepenetration-depth measurement

A temperature dependence of the penetration depth λ(T) measurement for the high-T_c superconductors YBa₂Cu ₃O_7-δ and Tl₂Ba₂CaCu ₂O₇ thin films elucidates a T² dependence at low temperatures and an exponential dependence at high temperatures. The transition temperature for the shift from T² to exponential dependence decreases as the duration for the samples exposed to air increases. An impurity scattered mechanism to fluctuate a pure d-wave to the s-wave by thermal fluctuation is proposed for the pairing states of these high-T_c superconducting films     

In vitro functional properties of the rat bladder regenerated by the bladder acellular matrix graft

PURPOSE: To assess the response of rat urinary bladder regenerated by the homologous bladder acellular matrix graft (BAMG) to in vitro electrical and pharmacologic stimuli. MATERIALS AND METHODS: In Sprague-Dawley rats, partial cystectomy (>50%) was performed, followed by BAMG augmentation cystoplasty. After 4 months, organ bath studies of tissue strips in 10 were used to compare the contractility of the BAMG regenerates and the corresponding host detrusor smooth muscle. RESULTS: The BAMG regenerates exhibited contractile activity to electrical field stimulation and a qualitatively identical pattern of response to muscarinic, purinergic, alpha- and beta-adrenergic drug administration and nitric oxide. At 4 months after surgery, the maximum forces of contraction of the BAMG regenerates to carbachol stimulation amounted to close to 80% of the host bladder response. With electrical field stimulation, they equaled 44% and 62% of the host bladder response after 2.5 and 4 months, respectively. Histological and immunohistochemical studies confirmed the presence of receptors for neurotransmitters that these functional in vitro studies implied. CONCLUSIONS: The present study provides further evidence that augmentation cystoplasty with the BAMG leads to functional regeneration of the rat bladder detrusor smooth muscle.