Minimizing the surface effect of PDMS–glass microchip on polymerase chain reaction by dynamic polymer passivation

Polydimethyl siloxane (PDMS)–glass microchip has a very strong surface effect on polymerase chain reaction (PCR), leading to a very poor PCR yield. In the work reported here, practical dynamic passivation of surfaces of PDMS–glass microchip using polyethylene glycol (PEG) or polyvinylpyrrolidone (PVP) was achieved using a conventional thermocycler. The passivation procedure was cost‐effective and easy to conduct. The effects of polymer molecular weight and polymer concentration on tube PCR efficiency were investigated primarily to prescreen out suitable polymers and polymer concentrations in the PCR mixture. The result from tube PCR indicated that both PEG and PVP could affect the performance of Taq polymerase. A final concentration of 0.025% (w/v) or 0.4% (w/v) polymer in the PCR mixture can enhance the tube PCR, while 1% (w/v) polymer was found to inhibit the reaction. PEG was more effective in tube PCR, although PVP performed better in chip PCR. Instead of employing the polymer directly in the PCR mixture, i.e. the conventional in situ passivation approach, another approach of dynamic passivation by pre‐injecting polymers into the microchip achieved better performance. The efficiency of pre‐passivation was found to follow the order: PVP10000>PVP55000, PEG8000> PEG10000>PEG400. After pre‐passivation with PVP10000, PVP55000 and PEG8000, the PCR efficiency can recover to 93%, 86% and 83%, respectively, of that obtained from tube PCR. Copyright © 2006 Society of Chemical Industry     

Application of economical models for dye removal from aqueous solutions: cash flow,cost–benefit,and alternative selection methods

Although there are numerous adsorption studies performed by using various adsorbents, there is no deterministic knowledge about selection of appropriate adsorbent type from present alternatives. In order to evaluate the advantages of the selected adsorbent species mathematically, researchers may use economical models such as cash flow diagrams, cost–benefit analyses, and alternative selection methods. In spite of the fact that these models have been used in many other engineering branches they are rarely applied in environmental research. In this study we have aimed to investigate usability of the mentioned economical models in adsorption of reactive azo dyes from aqueous solutions. Activated ash, a waste material, and commercial granular activated carbon were decided to be adsorbent alternatives. By applying economical models appropriate adsorbent type was selected considering both adsorption efficiencies and economical conditions. Although similar tendencies were monitored in cash flow diagrams; considering the amount of expenses activated ash exhibited remarkable advantages compared to granular activated carbon. Furthermore, results of cost–benefit analyses showed that activated ash has been advantageous when total costs and profits were evaluated together. Results of this study suggest usage of these economical models even in adsorption studies in order to provide accurate information on the selection of appropriate adsorbent type. These methods enable evaluation of economical conditions, which is generally neglected, together with the obtained removal efficiencies.     

Antioxidant and anticholinesterase evaluation of selected Turkish Salvia species

Since Salvia species (Lamiaceae) have been recorded to be used against memory loss in European folk medicine, we herein examined in vitro anticholinesterase and antioxidant activities of 56 extracts prepared with petroleum ether, chloroform, ethyl acetate and methanol obtained from 14 Salvia species (Salvia albimaculata Hedge and Hub, Salvia aucheri Bentham var. canescens Boiss and Heldr, Salvia candidissima Vahl. ssp. occidentalis, Salvia ceratophylla L., Salvia cryptantha Montbret and Bentham, Salvia cyanescens Boiss and Bal., Salvia frigida Boiss, Salvia forskahlei L., Salvia halophilaHedge, Salvia migrostegia Boiss and Bal., Salvia multicaulis Vahl., Salvia sclarea L., Salvia syriaca L., Salvia verticillata L. ssp. amasiaca) growing in Turkey. The antioxidant activities were assessed by both chemical and enzymatic methods against 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical-scavenging and xanthine/xanthine oxidase (XO) system generated superoxide anion radical inhibition. Anticholinesterase effect of the extracts was tested against both acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) at concentrations of 0.2 and 1 mg/ml using a microplate-reader assay based on the Ellman method. Most of the extracts did not show any activity against AChE at 0.2 mg/ml, while the chloroform extracts had noticeable inhibition against BChE between 47.7% and 74.7%. The most active extracts at 1 mg/ml for AChE inhibition were observed to be petroleum ether extract of Salvia albimaculata (89.4%) and chloroform extract of Salvia cyanescens (80.2%), whereas ethyl acetate extracts of Salvia frigida and Salvia migrostegia, chloroform extracts of Salvia candidissima ssp. occidentalis and Salvia ceratophylla, as well as petroleum ether extract of Salvia cyanescens were found to inhibit potently BChE (92.2%, 89.6%, 91.1%, 91.3%, and 91.8%, respectively). Particularly, the ethyl acetate and methanol extracts were observed to be highly active against both DPPH and XO. Our data indicates that nonpolar extracts of Salvia species for anticholinesterase activity and the polar extracts for antioxidant activity are worth further phytochemical evaluation for identifying their active components.     

A new approach for the computation of design shear force in reinforced concrete walls subjected to seismic loads

This paper investigates the dynamic shear amplification in reinforced concrete shear walls designed according to the seismic provisions of the current Turkish Building Earthquake Code (TBEC-2018). Shear walls with a high ductility level and different aspect ratios are examined to evaluate the design shear force calculated by using the dynamic amplification factor (β_v) and overstrength factor (D) defined in TBEC-2018. For this purpose, response spectrum analyses (RSAs) are first carried out on two-dimensional cantilever shear walls with heights of 30, 45, and 60 m and with lengths of 1.5, 3, and 4.5 m in the plan. Then, a total of 198 nonlinear time history analyses (NLTHAs) are performed with real and simulated ground motions matched to the elastic design spectrum defined in TBEC-2018. The comparison of the design shear forces obtained from RSA and the shear demands obtained from NLTHA along the heights of the walls reveals that the design shear forces calculated according to TBEC-2018 may underestimate the actual shear demands from studied ground motions. Moreover, the applicability of the updates proposed to TBEC-2018 for the design shear force and shear force diagram along the wall height in reinforced concrete shear wall-frame systems to cantilever shear walls is also examined.     

Effects of different surface treatment methods on the bond strength of composite resin to porcelain

In this study failures of composite resin/ porcelain interfaces under shear loading were examined. Porcelain firing were made onto metal cylinders and porcelain surfaces were roughened with burrs or treated with hydrofloric acid gel and/ or sandblasted with a Microetcher. Two silane coupling agents were used in five groups, each of which had 22 samples. All of the treated samples were restored with a hybrid-type composite resin. Then each group was divided into two subgroups according to storage times of 24 h and 30 days. After thermocyling the samples which were stored for 30 days, all of the groups were subjected to shear force at the composite resin/porcelain interface until fracture occurred. The results showed that there were differences both in the 24-h and 30-day storage period bond strengths between the various surface treatment methods. The samples treated with all three of the Microetcher, hydrofloric acid and silane exhibited the highest shear bond values after 24 h storage, followed by the microetched/silane and the hydrofluoric acid/silane groups (F: 570.31, P: 0.00). After 30 days, the highest mean shear bond strength values were again with samples treated by all three processes. The storage period and thermocycling decreased the bond strength of samples, however, there was a significant difference among groups (F: 1388-55, P: 0.00). Silane pre-treatment of porcelain was important as the mean bond strength of sandblasted/etched specimens were significantly lower than the other groups which were treated mechanically, in 24 h. Sandblasting seems to have little effect on the bonding. The comparison of 24-h and 30-day samples have also significant difference (F: 91.4376, P: 0.00).     

Cometabolic degradation of TCE in enriched nitrifying batch systems

The aim of this study was to evaluate the effect of the trace pollutant trichloroethylene (TCE) on the nitrification process and to assess its cometabolic degradation. Nitrification was accomplished in batch suspended growth systems containing an enriched nitrifier culture. The presence of TCE resulted in both the inhibition of specific oxygen uptake rate (SOUR) and specific ammonium utilization rate (qNH(4)-N). In both SOUR and qNH(4)-N a 50% decrease was observed in a TCE concentration range of 1000-2000 ppb. TCE was cometabolically degraded by this enriched nitrifier culture. The cometabolic degradation of TCE was found to be dependent on initial TCE concentration. The results may be applicable in the treatment of TCE containing industrial wastewaters and contaminated groundwaters and soils.     

Assessment of technological attributes of autochthonous starter cultures in Turkish dry fermented sausage (sucuk)

The study aims to evaluate the technological properties of autochthonous strains (Lactobacillus sakei S15, Lactobacillus plantarum S24, L. plantarum S91, Pediococcus pentosaceus S128b and Staphylococcus carnosus G109) in Turkish dry fermented sausage (sucuk). After 24 h of fermentaPtion, all lactic acid bacteria strains reduced the pH to below 5.0, while the pH in the control group was above 5.3. The number of lactic acid bacteria strains reached 10⁸–10⁹ cfu g⁻¹ during fermentation. Staphylococcus carnosus G109 remained at the inoculation level of 10⁶ cfu g⁻¹ during ripening. Lactobacillus sakei S15 as mono-culture showed higher TBARS values compared to other strains. The control group had the lowest L* value and autochthonous strains caused no significant difference for a* value. According to principal component analysis results, most volatile compounds were positively correlated with the group containing only L. sakei S15.     

Walnut consumption in a weight reduction intervention: effects on body weight,biological measures,blood pressure and satiety

Background

Dietary strategies that help patients adhere to a weight reduction diet may increase the likelihood of weight loss maintenance and improved long-term health outcomes. Regular nut consumption has been associated with better weight management and less adiposity. The objective of this study was to compare the effects of a walnut-enriched reduced-energy diet to a standard reduced-energy-density diet on weight, cardiovascular disease risk factors, and satiety.

Methods

Overweight and obese men and women (n =?100) were randomly assigned to a standard reduced-energy-density diet or a walnut-enriched (15% of energy) reduced-energy diet in the context of a behavioral weight loss intervention. Measurements were obtained at baseline and 3- and 6-month clinic visits. Participants rated hunger, fullness and anticipated prospective consumption at 3 time points during the intervention. Body measurements, blood pressure, physical activity, lipids, tocopherols and fatty acids were analyzed using repeated measures mixed models.

Results

Both study groups reduced body weight, body mass index and waist circumference (time effect p <?0.001 for each). Change in weight was ?9.4 (0.9)% vs. -8.9 (0.7)% (mean [SE]), for the standard vs. walnut-enriched diet groups, respectively. Systolic blood pressure decreased in both groups at 3 months, but only the walnut-enriched diet group maintained a lower systolic blood pressure at 6 months. The walnut-enriched diet group, but not the standard reduced-energy-density diet group, reduced total cholesterol and low-density lipoprotein cholesterol (LDL-C) at 6 months, from 203 to 194 mg/dL and 121 to 112 mg/dL, respectively (p <?0.05). Self-reported satiety was similar in the groups.

Conclusions

These findings provide further evidence that a walnut-enriched reduced-energy diet can promote weight loss that is comparable to a standard reduced-energy-density diet in the context of a behavioral weight loss intervention. Although weight loss in response to both dietary strategies was associated with improvements in cardiovascular disease risk factors, the walnut-enriched diet promoted more favorable effects on LDL-C and systolic blood pressure.

Trial registration

The trial is registered at (NCT02501889).