Shaking Water Bath Research Articles

Thermal Tolerance Characteristics of Non-O157 Shiga Toxigenic Strains of Escherichia coli (STEC) in a Beef Broth Model System Are Similar to Those of O157:H7 STEC

The non-O157 Shiga toxigenic Escherichia coli (STEC) serogroups most commonly associated with illness are O26, O45, O103, O111, O121, and O145. In the United States, these serogroups are considered adulterants in raw nonintact beef. To begin to understand the behavior of these pathogens in meat systems, we compared the thermal tolerance of acid-adapted cells of non-O157 STEC and O157:H7 STEC in a beef-derived broth. D58°C-values were determined for at least three strains per serogroup, and D54.6°C-values and D63.6°C-values were determined for one strain per serogroup. Each strain was grown to stationary phase in brain heart infusion broth (BHIB; pH 7.0) and inoculated into prewarmed BHIB in a shaking water bath for thermotolerance experiments at 54.6, 58.0, or 63.6°C (three trials per strain). Samples were heated for up to 160 min at 54.6°C, 3 min at 58.0°C, or 45 s at 63.6°C, with periodic sampling followed by rapid cooling and plating on modified Levine's eosin methylene blue agar. For each strain and temperature, the log CFU per milliliter was plotted versus time, and D-values were determined. Across all strains, the least and most heat tolerant STEC serogroups at 58°C were O145 and O157, respectively. D58°C-values in BHIB ranged from 0.44 min for an O145 strain to 1.42 min for an O157:H7 strain. D58°C-values for O157 STEC strains were significantly higher than those for at least one strain in each of the non-O157 STEC serogroups (P < 0.05) except for serogroup O103. At 54.6°C, the most heat-resistant STEC strain belonged to serogroup O103 and was significantly more heat tolerant than the O157:H7 strains (P < 0.05). Grouping the strains, there were no significant differences in heat tolerance between O157 and non-O157 STEC at 63.6°C (P ≥ 0.05). The z-values for non-O157 STEC strains were comparable to those for O157:H7 STEC strains (P ≥ 0.05), ranging from 4.10 to 5.21°C. These results suggest that thermal processing interventions that target destruction of E. coli O157:H7 may have adequate lethality against non-O157 STEC.

Changes of β-glucan physicochemical characteristics in frozen and freeze dried oat bran bread and porridge

The ability of oat foods to lower serum cholesterol and post-prandial blood glucose concentrations has been linked to the physicochemical properties of the bioactive component, mixed linkage β-glucan. Oat foods frequently need to be shipped or stored prior to analysis and β-glucan characteristics may change over time. Reductions in β-glucan solubility or molecular weight lead to lower viscosity development which decreases bioactivity. Impact of freezing and freeze drying conditions on the β-glucan physicochemical characteristics in oat bran bread and porridge were studied. Two in vitro digestibility methods were used to produce physiological extracts and the results were compared. The β-glucan molecular weight, solubility and viscosity for oat bread stored at room temperature were unchanged for 3 days, followed by a gradual decline in these parameters. The extract viscosity for bread decreased significantly after freezing at −80 °C and freeze drying after freezing at −18 and −80 °C, whereas freezing in liquid nitrogen did not significantly influence viscosity. Freezing of oat bran porridge did not affect extract viscosity, but freeze drying resulted in reduction of extract viscosity compared to the fresh porridge. Freezing and freeze drying did not dramatically affect the molecular weight or solubility of β-glucan in either product. The rapid visco analyzer was more effective and reliable for sample digestion than when physiological extraction was conducted in the shaking water bath. Generally, freezing at −18 °C or by submersion in liquid nitrogen maintained the physicochemical characteristics of β-glucan in food products either for commercial products or subsequent analysis.

Equilibrium Study on Reactive Extraction of Lactic Acid with Tri-n – Butyl Phosphate in n - Hexane

Extraction of carboxylic acids from dilute aqueous solution using traditional solvents such as ketones, alcohols, ethers, and ester is inefficient because the distribution ratio is rather low. Reactive extraction which exploits reversible chemical complexation is an effective separation process for extraction of carboxylic acids from aqueous streams such as fermentation broths and wastewaters. In the extraction process, selection of the solvent is an important aspect to be considered. Considering its solubility in water, cost and availability, tri-n-butyl phosphate (TBP) seems to be an attractive solvent for the extraction of lactic acid from aqueous solution. The purpose of this experiment is to study the equilibrium of the reactive extraction of lactic acid in aqueous solution with TBP in n-hexane. The parameters studied in this experiment were initial concentration of lactic acid in the aqueous phase, TBP concentration in n-hexane phase, and the extraction temperature. The experiments at ambient temperature were carried out using a separatory funnel, while the experiments at other than ambient temperature were carried out using erlenmeyer flask and water bath shaker to adjust the temperature. In this experiment, the initial concentration of lactic acid was varied from 0.1 to 0.5 gmol/dm3. The range of initial TBP concentrations in n-hexane was 0.1 to 1.0 gmol/dm3 and the extraction temperature range was 283 to 313 K. The experimental results showed that the higher the initial concentration of lactic acid in aqueous solution, the higher the distribution ratio for a fixed TBP concentration and extraction temperature. For a fixed initial concentration of lactic acid in aqueous solution and extraction temperature, the distribution ratio of lactic acid is increased by increasing TBP concentration. The overall equilibrium constants (Kpq) for the experiments using TBP concentration ranging from 0.1 to 1.0 gmol/dm3 at the extraction temperature of 293 K are calculated to be 0.0668 to 0.5144. Kpq for the experiments at the temperature ranging from 283 to 313 K at the initial concentration of lactic acid of 0.2 gmol/L are found to be 0.0122 to 0.8856. The Kpq as a function of temperature (T) in K can be expressed as ln Kpq = 10,596/T - 38.08 with sum of square of error of 0.14.

Development of an ex vivo model for investigating the bacterial association to the gut epithelium of pigs

To study enterotoxigenic Escherichia coli (ETEC) association to the gut of pigs, a simple and reproducible experimental model would be helpful. The aim of this experiment was to establish a model for studying the association of ETEC to the gut epithelium of pigs. Intestinal segments were prepared from 4 weaned pigs, which were tested susceptible to E. coli O149:F4 (homo- and heterozygotic; 2 pigs each) and O138:F18 (all homozygotic). Five segments were taken from 50% of the intestinal length measured from duodenum [mid small intestine (SI)], and 5 segments were taken from 90% distal to the duodenum (distal SI). The segments were immersed in Dulbecco's Modified Eagle Medium (DMEM) and kept on ice. Polyethylene tubing was inserted into either end of the segment and tied. The tissue was washed with 50 mL of PBS. The other end of segment was tied, 10 mL of DMEM alone or DMEM containing either E. coli F4 or F18 was inoculated, and the segment was sealed with Teflon plug. The segment was immersed in DMEM in a 300-mL infusion bottle in a shaking water bath at 37°C. After 1 h the segment was removed, tissue was washed with 50 mL of PBS, weighed, and homogenized in PBS. Final dilution of 10(-6) was prepared from the content and homogenate. The E. coli was enumerated on MacConkey agar. Data were analyzed according to a 2 × 3 × 2 parametric model including the effects of intestinal segment, E. coli strain, and site of SI with GLM procedure in SAS. A t-test was used to analyze the effect of genotype in F4-inoculated segment. The binding of E. coli on the tissue was 10 times higher (P < 0.001) for F4 than F18. The E. coli F18 was highest (P < 0.05) in mid SI whereas differences were not observed (P > 0.05) between sites of SI for F4. Fewer (P < 0.001) bacteria bound in the control and they associated more (P = 0.10) at distal than mid SI. The E. coli did not differ (P > 0.05) between genotypes in F4-inoculated segment. In conclusion, the ex vivo model may be feasible to investigate the ETEC association to the gut epithelium of pigs.

Expression of Platelet (PLT) P-Selectin and PLT-Neutrophil (PMN) Interaction After Treatment of Whole Blood with Mirasol® PRT.

AbstractAbstract 2288 IntroductionPlatelet concentrates develop biologically active compounds during storage which may play a role in adverse events of transfusion. Although many studies have focused on release of soluble pro-inflammatory compounds, changes in cells such as platelets may contribute to the response or pro-inflammatory effects of transfusion products. In previous studies we have shown that pathogen reduction with Mirasol PRT of apheresis PLT concentrates induced changes in PLTs which increased during storage including expression of P-selectin and the capacity to form PLT-PMN aggregates. These changes were also associated with increased adherence of stored PLTs in a microfluidic chamber. In the current study we evaluated P-selectin and PLT-PMN aggregate formation in whole blood after treatment with Mirasol PRT. MethodsTen units of whole blood from healthy donors were drawn into CPD under an IRB approved protocol. Five units where treated with Mirasol PRT and five units remained untreated. Aliquots were taken before and after treatment (or at same times for untreated units) on Day 0 and 24–27 hours after draw on Day 1 after storage at 22–24°C. Platelet rich plasma (PRP) was produced by standard technique and PLTs isolated on a Sepharose 2B column. PLTs were incubated with APC-CD62P and FITC-CD41a for comparison with P-selectin expressed as percent positive increase over isotype control. PMNs were isolated from 50 ml of heparinized peripheral blood drawn from healthy, ABO-matched donors. After a 5 min pre-incubation at 37°C in a shaking water bath, untreated, treated PLTs, and PMNs were incubated separately or together for 3 min then quenched at 4°C. FITC-CD41a and FITC-IgG1 isotype for platelet-PMN aggregate quantitation or PE-CD11b for CD11b expression on neutrophils were added. Platelet-PMN aggregates was expressed as percent of all PMN events above CD41a isotype control. CD11b expression was determined for PMNs after exposure to PLTs by flow cytometry. ResultsP-selectin positive cells did not change significantly over time in samples from untreated products (Table 1). After Mirasol PRT treatment, cells positive for P-selectin increased on Day 0 and 1 (p<0.005, two-tailed t-test). Treated products, compared to untreated products demonstrated significantly increased P-selectin expression on Day 1.Table 1P-selectin Expression on PLTsSample% PLTs positive for P-selectinUntreated WBDay 0, earlyDay 0, lateDay 110.2 ± 2.2*15.2 ± 3.312.3 ± 2.3Mirasol PRT treatedDay 0, preDay 0, postDay 17.6 ± 1.119.0 ± 2.521.7 ± 2.6***Numbers represent mean ± SEM for 5 separate products each**Treated cells different than untreated cells, p<0.05Results for PMN-PLT aggregates parallel expression of P-selectin (Table 2). No increase in aggregate formation was seen for untreated samples; however, treated samples showed increased aggregates at Day 0 and 1 (p<0.005). Aggregates with PMNs were increased in treated samples in comparison to untreated samples on Day 1.Table 2PLT-PMN AggregatesSample% PMNs with associated PLTsUntreated WBDay 0, earlyDay 0, lateDay 17.8 ± 4.49.8 ± 3.37.1 ± 3.8Mirasol PRT treatedDay 0, preDay 0, postDay 14.8 ± 3.015.5 ± 3.519.3 ± 6.9**No differences were seen with CD11b expression on PMNs after exposure of treated or untreated PLTs at any of the times studied.*Numbers represent mean ± SEM for 5 separate products each**Treated cells different than untreated cells, p<0.05 ConclusionTreatment of whole blood with Mirasol PRT results in increased expression of P-selectin on PLTs and capability of forming aggregates with PMNs. The changes occur soon after initiation of treatment, and the implications for clinical response to of platelet infusion and adverse events of transfusion need to be established. Disclosures:Ambruso:Terumo BCT: Research Funding. Seewald:Terumo BCT: Research Funding. Marschner:Terumo BCT: Employment. Goodrich:Terumo BCT: Employment.

Optimization of Lipase-Mediated Synthesis of 1-Nonene Oxide Using Phenylacetic Acid and Hydrogen Peroxide

Herein, an efficient epoxidation of 1-nonene is described. In a simple epoxidation system, commercially available Novozym 435, an immobilized Candida antarctica lipase B, and hydrogen peroxide (H2O2) were utilized to facilitate the in situ oxidation of phenylacetic acid to the corresponding peroxy acid which then reacted with 1-nonene to give 1-nonene oxide with high yield and selectivity. The aliphatic terminal alkene was epoxidised efficiently in chloroform to give an excellent yield (97%–99%) under the optimum reaction conditions, including temperature (35 °C), initial H2O2 concentration (30%), H2O2 amount (4.4 mmol), H2O2 addition rate (one step), acid amount (8.8 mmol), and stirring speed (250 rpm). Interestingly, the enzyme was stable under the single-step addition of H2O2 with a catalytic activity of 190.0 Ug−1. The entire epoxidation process was carried out within 12 h using a conventional water bath shaker.

Enzyme-facilitated synthesis of 1-nonene oxide and simple GC-MS SIM method for rapid screening of epoxidation processes

Here, we describe an improved enzyme-facilitated epoxidation of 1-nonene using a conventional water bath shaker at ambient temperature. Enzymes were used to produce peroxy acids instantly from hydrogen peroxide (H2O2) and various perhydrolysis substrates. The peroxy acid generated was then utilised directly for in-situ oxidation of 1-nonene to 1-nonene oxide. Various parameters affecting the reaction were studied such as the nature of the peroxy acids, organic solvents, enzyme sources and enzyme concentrations. The highest conversion rate was achieved using phenylacetic acid as an oxygen carrier. 1-Nonene was converted most efficiently with 95% of the maximum yield by Novozym 435, an immobilised Candida antarctica lipase B, using dichloromethane as the reaction media. A minimum amount (16 mg, 1.4% w/w) of Novozym 435 was needed to maintain catalytic activity (160.0 Ug−1). In addition, a simple and rapid Gas chromatography mass spectroscopy selective ion monitoring (GC-MS SIM) method was developed using a HP-5ms column for determining 1-nonene oxide. The method was found to be linear in the range of 29.9 to 298.8 mg/L with R2 = 0.9981.

석류 종자유로부터 얻어진 Conjugated Linolenic Acid를 함유한 기능성 고체지의 효소적 합성 및 이화학적 특성 연구

기능성 지방산인 CLnA를 다량 함유하고 있는 석류 종자유로부터 합성된 가수분해물과 고체지인 팜 스테아린을 기질로 사용하여 Lipozyme TL IM 효소를 촉매로 하여, 기능성 고체지들을 무용매 반응(NH-SL)과 n-hexane 반응(H-SL)조건에서 합성하였다. 합성은 기질 비율 1:6 몰(w/w, PS:HPSO)로, 각 12, 24, 72 hr 동안 반응하여 이루어졌다. 합성 후 반응물은 탈산과정을 수행한 후 각 기능성 고체지들의 이화학적 특성을 살펴보았다. 총 지방산 조성분석결과, 반응시간이 증가함에 따라 NH-SL에서 CLnA의 함량은 34.38%, 37.68%, 40.63%의 함량으로 유의적 차이를 보이며 증가하는 경향을 나타내었다(p<0.05). H-SL에서 CLnA의 함량은 36.81%, 41.19%, 45.83%으로 유의적 차이를 보이며 증가하였다(p<0.05). TAG 조성분석 결과, 기능성 재구성지질들(NH-SL, H-SL)에는 LnLnLn(PN=36), LnLnL(PN=38), LnLL과 LnLnP(PN=40), LLL(PN=42), PLP(PN=46), OOLn과 PLO, POP, PPS(PN=48), LOO, POS(PN=50) 등으로 구성되어 있었다. 반응시간이 길어짐에 따라 NH-SL의 경우 LnLnLn의 함량이 1.63%에서 11.54%로 증가하였고, H-SL의 경우 5.89%에서 18.45%로 증가하였다. 또한 주된 TAG 조성인 LnLnP의 경우 각각 23.15~33.77%(NH-SL)와 28.76~36.44%(H-SL)으로 높은 함량을 나타내었다. 합성한 석류종자유 가수분해물의 산가는 200.46이었으며, 합성 후 탈산한 기능성 고체지들의 산가는 1.05~1.41로 낮았다. 또한 불포화도를 나타내는 요오드가 측정결과, 무용매 반응과 용매 반응 모두에서 반응시간이 길어짐에 따라 요오드가가 점차로 증가하였다. 이러한 결과는 반응시간이 길어짐에 따라 CLnA의 함량이 높아졌기 때문에 IV가 점차로 높아지는 결과를 얻은 것으로 사료된다. 기능성 고체지들의 total tocopherol 함량 측정결과, 반응시간이 길어짐에 따라 NH-SL의 경우 3.37~2.13 mg/100 g으로 다소 감소하였으며, H-SL의 경우 3.89~2.51 mg/100 g으로 감소하는 경향을 나타내었다. 또한, 기능성 고체지들의 SFI 측정결과, H-SL의 경우 <TEX>$10^{\circ}C$</TEX>에서 NH-SL보다 고체지 함량이 낮았으며, <TEX>$25^{\circ}C$</TEX>에서는 거의 액체 상태를 유지하였다. 이는 융점이 낮으며 불포화지방산인 CLnA의 함량이 비교적 높았기 때문인 것으로 사료된다. 따라서 마가린과 같은 적절한 spreadability를 부여하기 위해서는 무용매 반응(NH-SL)에서 12 hr과 24 hr 반응을 통하여 생성된 기능성 고체지들이 적합할 것으로 예측되었다. 72 hr 동안 반응하여 생성된 기능성 고체지들(NH-SL, H-SL)의 경우, <TEX>$3.86{\AA}$</TEX>에서 낮은 강도를 나타내어, 주로 <TEX>${\beta}$</TEX>'의 결정형을 이루고 있음을 확인하였다. Lipozyme TL IM-catalyzed esterification was carried out to produce functional hard fat (structured lipid, SL) using palm stearin (PS) and hydrolysate of pomegranate seed oil (HPSO) of 1:6 molar ratio. HPSO contained conjugated linolenic acid (CLnA, about 80%). The reaction was performed at non-solvent system and solvent (n-hexane) system using Lipozyme TL IM (10% of total substrates, w/w) for 12, 24, and 72 hr in a shaking water bath (<TEX>$55^{\circ}C$</TEX> and 185 rpm), respectively. SL synthesized in non-solvent system (NH-SL) and SL synthesized in n-hexane system (H-SL) were refined after deacidification, respectively. Their physicochemical properties were compared to obtain desirable functional hard fat. The content of CLnA in NH-SL increased from 34.38% to 40.63% with increasing reaction time. Similar results also observed in H-SL resulting in 36.81~45.83% of CLnA. In triacylglycerol (TAG) composition, the main molecules of LnLnLn (Ln=linolenic acid, PN=36) and the LnLnP (P=palmitic acid, PN=40) were newly synthesized in NH-SL and H-SL with increasing reaction time. After 72 hr reaction, iodine values of NH-SL (136.49) and H-SL (140.37) showed high values because of the high content of CLnA. Solid fat index (SFI) in NH-SL was higher than that in H-SL at each measured temperature. The predominant polymorphic forms of NH-SL and H-SL obtained after esterification for 72 hr were the desirable crystalline structure of the <TEX>${\beta}$</TEX>' form.

Release and Bioaccessibility of β-Carotene from Fortified Almond Butter during in Vitro Digestion

The objective of this study was to determine the release and bioaccessibility of β-carotene from fortified almond butter using in vitro digestion models. Two types of fortifiers were investigated: β-carotene oil (oil) and whey protein isolate (WPI)-alginate-chitosan capsules containing β-carotene oil (capsule). Shaking water bath and Human Gastric Simulator (HGS) digestion models assessed the impact of gastric peristalsis on the release of β-carotene. Bioaccessibility of β-carotene was measured as percent recovered from the micelle fraction. There was greater release of β-carotene from oil fortified almond butter in the HGS model (87.1%) due to peristalsis than the shaking water bath model (51.0%). More β-carotene was released from capsule fortified almond butter during intestinal digestion. However, more β-carotene was recovered from the micelle fraction of oil fortified almond butter. These results suggest that a WPI-alginate-chitosan capsule coating may inhibit the bioaccessibility of β-carotene from fortified almond butter.

Determination of optimal conditions for laccase production by Pleurotus ostreatus using sawdust as solid medium and its use in phenol degradation

The ability of four local fungal isolates for extracellular laccase production has been tested with five grams 1:1(w/v) humidified sawdust as substrate in mineral salt medium. After 21 day of incubation at 25±1 ? C and using one mycelial plug (5mm), higher level of laccase activity (0.15U/ml) and specific activity (15U/mg) were observed by Pleurotus ostreatus in comparison with other fungal isolates. The results of optimum conditions for laccase production from selected isolate showed that, the maximum laccase activity (0.55U/ml) and specific activity (55U/mg) were obtained at moisture ratio 1:3 (w/v), using 3 mycelial plugs (5 mm), after 15 days incubation period at 25±1 ? C. The results of phenol degradation by crud laccase revealed that, 100% degradation of phenol occurred after 24 hr of incubation at 25 ? C using shaking water bath except at 200mg/l, the remaining phenol was 10.13%.

Determination of optimal conditions for laccase production by Pleurotus ostreatus using sawdust as solid medium and its use in phenol degradation

The ability of four local fungal isolates for extracellular laccase production has been tested with five grams 1:1(w/v) humidified sawdust as substrate in mineral salt medium. After 21 day of incubation at 25±1 ? C and using one mycelial plug (5mm), higher level of laccase activity (0.15U/ml) and specific activity (15U/mg) were observed by Pleurotus ostreatus in comparison with other fungal isolates. The results of optimum conditions for laccase production from selected isolate showed that, the maximum laccase activity (0.55U/ml) and specific activity (55U/mg) were obtained at moisture ratio 1:3 (w/v), using 3 mycelial plugs (5 mm), after 15 days incubation period at 25±1 ? C. The results of phenol degradation by crud laccase revealed that, 100% degradation of phenol occurred after 24 hr of incubation at 25 ? C using shaking water bath except at 200mg/l, the remaining phenol was 10.13%.

ATP secretion in the male reproductive tract: essential role of CFTR

Extracellular ATP is essential for the function of the epididymis and spermatozoa, but ATP release in the epididymis remains uncharacterized. We investigated here whether epithelial cells release ATP into the lumen of the epididymis, and we examined the role of the cystic fibrosis transmembrane conductance regulator (CFTR), a Cl(-) and HCO(3)(-) conducting ion channel known to be associated with male fertility, in this process. Immunofluorescence labelling of mouse cauda epididymidis showed expression of CFTR in principal cells but not in other epithelial cells. CFTR mRNA was not detectable in clear cells isolated by fluorescence-activated cell sorting (FACS) from B1-EGFP mice, which express enhanced green fluorescent protein (EGFP) exclusively in these cells in the epididymis. ATP release was detected from the mouse epididymal principal cell line (DC2) and increased by adrenaline and forskolin. Inhibition of CFTR with CFTR(inh172) and transfection with CFTR-specific siRNAs in DC2 cells reduced basal and forskolin-activated ATP release. CFTR-dependent ATP release was also observed in primary cultures of mouse epididymal epithelial cells. In addition, steady-state ATP release was detected in vivo in mice, by measuring ATP concentration in a solution perfused through the lumen of the cauda epididymidis tubule and collected by cannulation of the vas deferens. Luminal CFTR(inh172) reduced the ATP concentration detected in the perfusate. This study shows that CFTR is involved in the regulation of ATP release from principal cells in the cauda epididymidis. Given that mutations in CFTR are a leading cause of male infertility, we propose that defective ATP signalling in the epididymis might contribute to dysfunction of the male reproductive tract associated with these mutations.

Release of Ciprofloxacin-HCl and Dexamethasone Phosphate by Hyaluronic Acid Containing Silicone Polymers.

The purpose of this study was to determine the effect of the covalent incorporation of hyaluronic acid (HA) into conventional hydrogel and hydrogels containing silicone as models for contact lens materials on the uptake and release of the fluoroquinolone antibiotic ciprofloxacin and the anti-inflammatory steroid dexamethasone phosphate. A 3 mg/mL ciprofloxacin solution (0.3% w/v) and a 1 mg/mL dexamethasone phosphate solution (0.1%) was prepared in borate buffered saline. Three hydrogel material samples (pHEMA; pHEMA TRIS; DMAA TRIS) were prepared with and without the covalent incorporation of HA of molecular weight (MW) 35 or 132 kDa. Hydrogel discs were punched from a sheet of material with a uniform diameter of 5 mm. Uptake kinetics were evaluated at room temperature by soaking the discs for 24 h. Release kinetics were evaluated by placing the drug-loaded discs in saline at 34 °C in a shaking water bath. At various time points over 6–7 days, aliquots of the release medium were assayed for drug amounts. The majority of the materials tested released sufficient drug to be clinically relevant in an ophthalmic application, reaching desired concentrations for antibiotic or anti-inflammatory activity in solution. Overall, the silicone-based hydrogels (pHEMA TRIS and DMAA TRIS), released lower amounts of drug than the conventional pHEMA material (p < 0.001). Materials with HA MW132 released more ciprofloxacin compared to materials with HA MW35 and lenses without HA (p < 0.02). Some HA-based materials were still releasing the drug after 6 days.

A New, Highly Conductive, Lithium Salt/Nonionic Surfactant, Lyotropic Liquid‐Crystalline Mesophase and Its Application

Highly conductive electrolyte materials are an essential part of many electrochemical systems, such as fuel cells, solar cells, batteries, electrochromic devices, and next-generation renewable-energy sources. The growing diversity in batteries and electrochemical cells increases the demand for novel electrolyte materials. For instance, in solar-cell applications, an electrolyte material with high viscosity and low volatility is desirable, together with high ionic conductivity. Electrolytes can be solids, gels, or liquids depending on the application. Gel electrolytes are advantageous when the conductivity in the solid form is not sufficient or the leakage or vaporization of the liquid electrolyte is a problem. Gel electrolytes can be aqueous or non-aqueous depending on the application type. While in some battery systems aqueous gel electrolytes have no use—for example, in Li ion batteries—they can be used in many rechargeable batteries, electrochemical capacitors, solar cells, and so on. Liquid-crystal gel electrolytes have also been investigated and are considered to be an important class of ordered materials for the above applications. A lyotropic liquid-crystalline (LLC) mesophase is formed by two main constituents: an amphiphile and a solvent. Common solvents are water, organic liquids, or ionic liquids. LLC-based electrolytes offer many advantages, like rigidity and high ionic mobility and can be an alternative to polymer electrolytes. Solvent-free LC systems (thermotropic LC) usually have low ionic conductivities at room temperature, typically around 10 6 Scm , whereas solvent-containing LLC systems have room-temperature ionic conductivities around 10 3 Scm . Usually high ionic conductivity in solvent-free LC electrolyte systems is achieved at high temperatures, that is, 150 8C and above. Recently we have shown that transition-metal aqua complex salts ([M ACHTUNGTRENNUNG(H2O)6]X2; in which M is a transition-metal cation and X is a suitable counterion), which have melting points close to room temperature, can also be used as solvents in the self-assembly process of some surfactants. The LLC mesophases of molten transition-metal-salt aqua complexes have important physical properties, such as high thermal stability (between 83 and 383 K), high ionic conductivity (room-temperature conductivities close to 2.0 10 4 Scm ), and nonvolatility. A highly concentrated aqueous electrolyte solution of an alkali metal salt can also act as a solvent in the assembly process of oligo(ethylene oxide) type surfactants, in which the highly concentrated electrolyte solution can be considered as an analogue of a molten salt. Their similarities arise due to strong ion–dipole (salt–water) interactions at high salt concentrations (highly concentrated refers to water/salt mole ratios of less than 8 in the case of lithium salts) and as a consequence, the heat of vaporization of water sharply increases. In this contribution, we have investigated the phase behavior and ionic conductivity of a new class of hydrated-salt/ surfactant mesophase, namely; LiNO3–H2O–C12EO10, LiCl– H2O–C12EO10, and LiClO4–H2O–C12EO10 systems, in which C12EO10 is C12H25 ACHTUNGTRENNUNG(OCH2CH2)10OH. The mesophase is a collaborative assembly of a hydrated salt species in the liquid phase and surfactant molecules. Earlier studies on salt– water–surfactant mesophases focus on the effect of salts on the phase behavior of surfactants in dilute aqueous solutions (18–1, water/salt mole ratio). Here, we demonstrate that as little as two water molecules per molecule of lithium salt is sufficient to form a LLC mesophase. At such a low water and high salt concentrations, the bulk properties of water are altered by the salt–water interactions and the salt– water couple collaboratively acts as the solvent in the LLC mesophase. An important outcome of the salt–water interaction is that the LLC mesophase is stable under ambient atmospheric conditions for years (see Supporting Information) and displays high ionic conductivity over a broad temperature range. The LLC samples were prepared by adding each ingredient: salt (LiNO3, LiCl, or LiClO4), surfactant (C12EO10), and water in the required amounts and the resulting mixture was then homogenized by constant shaking in a shaking water bath at 60–110 8C for 24 h. Under ambient conditions, the amount of water in the samples depends on the temperature, relative humidity, and the amount of salt in the mesophase, but always enough water remains in the samples to [a] C. Albayrak, Prof. . Dag Department of Chemistry, Bilkent University 06800, Ankara (Turkey) Fax: (+90)312-266-4068 E-mail : dag@fen.bilkent.edu.tr [b] Prof. A. Cihaner Department of Chemical Engineering and Applied Chemistry Atilim University 06836, Ankara (Turkey) Supporting information for this article is available on the WWW under http://dx.doi.org/10.1002/chem.201103705.

Degradation of electrospun poly(L‐lactide) membranes under cyclic loading

AbstractBecause of the great effect of mechanical loads on degradation of biodegradable biomaterials, investigation on degradation of electrospun membranes under dynamic loading is of importance. In this article, degradation of electrospun poly(L‐lactide) (PLLA) membranes was carried out in a Tris‐HCl buffer solution containing proteinase K under a cyclic stretch loading (dynamic condition) in comparison with that in shaking water bath (static condition). The evolutions of mass loss, morphology, thermal properties, and relative molecular weight of PLLA were monitored during degradation. The results showed that after degradation for 10 h, the mass of the electrospun PLLA membranes dropped by 38.7% and 31.3%, respectively, under dynamic and static conditions. And the electrospun PLLA membranes showed higher value of crystallinity during degradation under both cyclic loading and static condition. In addition, benzyl triethyl ammonium chloride (BTEAC) was introduced during electrospinning, and the effects of electrospun membranes characteristic and crystallinity on degradation were also investigated. The degradation study results are expected to be a basic study in mimicking actually mechanical environments. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci 124:258–266, 2012

Preparation and Characterization of Faujasite using Fly Ash and Amorphous Silica from Rice Husk Ash

Zeolite was synthesized by using fly ash and amorphous silica from rice husk ash as the raw materials. Amorphous silica was mixed with fly ash and then fused by fusion method prior to incubation at low temperature. The objectives of this research were to prepare zeolite using fly ash and amorphous silica from rice husk ash and to study the effect of amorphous silica content on crystallization time of the synthesis products. Fly ash was mixed with amorphous silica in the ratios of 10:0, 8:2, 7:3, 6:4 and 5:5 (wt/wt). Then, the mixtures were ground with sodium hydroxide in the ratio of 1:1 and fused at 823K for 1h. Subsequently, the ground samples were dissolved in 100ml of distilled water and put into shaking water bath. The mixture of fly ash and amorphous silica in ratio of 7:3 generated the highest yield and crystallinity of zeolite (faujasite type). Moreover, the crystallization time was studied at 343K after left the mixture for 1, 2, 3 and 4 days, respectively. The results showed that the faujasite phase was found after left for 1 day. Then, the morphology of faujasite was confirmed by using SEM which indicated that the octahedral crystal of faujasite. The results were confirmed by FTIR, CEC and BET techniques. FTIR spectra exhibited the presence of internal Si-O-Si and Si-O-Al asymmetric stretching mode. The CEC and specific surface area of faujasite were 3.6 meq/g and 233 m2/g, respectively.

Microemulsions of Potassium Oleate, Tween-20, Propylene Carbonate, and Ethylene Glycol as Drug Vehicles for Mefenamic Acid

Different microemulsions were prepared with and without mefenamic acid (MFA). The base microemulsion was mainly composed of distilled water; the aqueous phase, propylene carbonate; the oil phase, potassium oleate; the surfactant, and finally di-ethylene glycol; the cosurfactant. The effect of mixing ionic (potassium oleate) with nonionic (Tween-20) surfactant was investigated via constructing the phase diagrams of such systems. Changes in conductivity and viscosity of the freshly prepared microemulsion over time were monitored as an indication for the stability of the microemulsion. Measurements were carried out at room temperature, after a freeze-thaw cycle and also after storage for 3 days at 60°C, where the latter is treated as an accelerated test for the time-temperature effects on the stability of a microemulsion. It was found that a set of surfactants, instead of a single surfactant, and inclusion of cosurfactant resulted in a broader region where a stable microemulsion is predominant. At a mass ratio of 1:2 of potassium oleate to Tween-20, O/W microemulsions were found to have maximum stability among all examined systems, under the accelerated test, such that they have a minimum portion of combined surfactants and cosurfactant of 60 wt% and maximum of 80 wt%. With the aforementioned specifications, no phase separation and neither significant change in the conductivity nor in the viscosity was observed in any of the examined systems after subjecting them both to the accelerated and freeze-thaw cycle test, indicating that such systems were thermodynamically stable. Samples of micro emulsions passing previous tests were further subjected to an acidic medium by dispersing 1 g of MFA-containing microemulsion in 10 g HCl solution (pH 1) in a shaking water bath at 37°C, for a 6 hour period. The maximum solubility of MFA in a stable microemulsion was approximately 5 wt%, evaluated at room temperature.

Green Tea Polyphenols Control Dysregulated Glutamate Dehydrogenase in Transgenic Mice by Hijacking the ADP Activation Site

Glutamate dehydrogenase (GDH) catalyzes the oxidative deamination of L-glutamate and, in animals, is extensively regulated by a number of metabolites. Gain of function mutations in GDH that abrogate GTP inhibition cause the hyperinsulinism/hyperammonemia syndrome (HHS), resulting in increased pancreatic β-cell responsiveness to leucine and susceptibility to hypoglycemia following high protein meals. We have previously shown that two of the polyphenols from green tea (epigallocatechin gallate (EGCG) and epicatechin gallate (ECG)) inhibit GDH in vitro and that EGCG blocks GDH-mediated insulin secretion in wild type rat islets. Using structural and site-directed mutagenesis studies, we demonstrate that ECG binds to the same site as the allosteric regulator, ADP. Perifusion assays using pancreatic islets from transgenic mice expressing a human HHS form of GDH demonstrate that the hyperresponse to glutamine caused by dysregulated GDH is blocked by the addition of EGCG. As observed in HHS patients, these transgenic mice are hypersensitive to amino acid feeding, and this is abrogated by oral administration of EGCG prior to challenge. Finally, the low basal blood glucose level in the HHS mouse model is improved upon chronic administration of EGCG. These results suggest that this common natural product or some derivative thereof may prove useful in controlling this genetic disorder. Of broader clinical implication is that other groups have shown that restriction of glutamine catabolism via these GDH inhibitors can be useful in treating various tumors. This HHS transgenic mouse model offers a highly useful means to test these agents in vivo.

Mfc1 Is a Novel Forespore Membrane Copper Transporter in Meiotic and Sporulating Cells

To gain insight in the molecular basis of copper homeostasis during meiosis, we have used DNA microarrays to analyze meiotic gene expression in the model yeast Schizosaccharomyces pombe. Profiling data identified a novel meiosis-specific gene, termed mfc1(+), that encodes a putative major facilitator superfamily-type transporter. Although Mfc1 does not exhibit any significant sequence homology with the copper permease Ctr4, it contains four putative copper-binding motifs that are typically found in members of the copper transporter family of copper transporters. Similarly to the ctr4(+) gene, the transcription of mfc1(+) was induced by low concentrations of copper. However, its temporal expression profile during meiosis was distinct to ctr4(+). Whereas Ctr4 was observed at the plasma membrane shortly after induction of meiosis, Mfc1 appeared later in precursor vesicles and, subsequently, at the forespore membrane of ascospores. Using the fluorescent copper-binding tracker Coppersensor-1 (CS1), labile cellular copper was primarily detected in the forespores in an mfc1(+)/mfc1(+) strain, whereas an mfc1Δ/mfc1Δ mutant exhibited an intracellular dispersed punctate distribution of labile copper ions. In addition, the copper amine oxidase Cao1, which localized primarily in the forespores of asci, was fully active in mfc1(+)/mfc1(+) cells, but its activity was drastically reduced in an mfc1Δ/mfc1Δ strain. Furthermore, our data showed that meiotic cells that express the mfc1(+) gene have a distinct developmental advantage over mfc1Δ/mfc1Δ mutant cells when copper is limiting. Taken together, the data reveal that Mfc1 serves to transport copper for accurate and timely meiotic differentiation under copper-limiting conditions.

팜중부유를 이용한 대칭형 Palmitoyl-Oleoyl-Stearoyl Triacylglycerol의 효소적 합성 반응 연구

본 연구에서는 palm mid fraction(PMF)와 stearic ethyl ester를 기질로 Lipozyme TLIM을 이용한 에스테르 교환반응을 실시하였으며 기질의 몰 비율과 효소양 및 시간에 따른 TAG 조성 변화와 함께 POS 구성율 및 acyl migration 정도를 알아보았다. sn-2 위치에서의 주요 지방산 조성 변화는 몰 비율과 효소양, 반응시간이 증가할수록 C18:1은 점차 감소하였고, C16:0과 C18:0은 증가함을 알 수 있었다. 이와 같은 변화는 특히 반응시간이 증가함에 따라 두드러지게 나타났으며 acyl migration 생성과 관계가 깊은 것으로 예측되었다. 그 결과 총 포화지방산의 함량은 최고 37.4 area%까지 증가한 수치를 보였다. 반응 합성물의 주요 TAG 조성으로는 POP, POS, SOS와 같은 대칭형 구조의 TAG가 확인되었으며 반응이 진행됨에 따라 POP는 감소하고 POS가 증가하는 경향을 보였다. Acyl migration과 POS 함량을 고려하였을 때 몰 비율 1:2, 효소양 3 wt%, 5시간 반응 조건에서 POS는 53.5 area%의 높은 함량을 보였으며 이때 총 포화지방산 함량은 반응 전 11.9 area%와 비교하여 약 2배 증가한 23.1 area%를 나타내었다. 한편, 전체 반응 조건 중 가장 높은 POS 함량은 55.4 area%의 수치를 보였는데, 이후 몰 비율과 효소양의 증가와 더불어 반응시간이 지속되었음에도 불구하고 POS는 오히려 감소하는 것을 확인할 수 있었다. 또한 반응이 진행되면서 acyl migration에 의해 sn-2 위치에 palmitic acid와 stearic acid가 전이된 PPS, PSS, SSS와 같은 TAG의 생성도 증가함을 알 수 있었다.