Subsurface diffuse optical tomography can localize absorber and fluorescent objects but recovered image sensitivity is nonlinear with depth

Subsurface tomography with diffuse light has been investigated with a noncontact approach to characterize the performance of absorption and fluorescence imaging. Using both simulations and experiments, the reconstruction of local subsurface heterogeneity is demonstrated, but the recovery of target size and fluorophore concentration is not linear when changes in depth occur, whereas the mean position of the object for experimental fluorescent and absorber targets is accurate to within 0.5 and 1.45 mm when located within the first 10 mm below the surface. Improvements in the linearity of the response with depth appear to remain challenging and may ultimately limit the approach to detection rather than characterization applications. However, increases in tissue curvature and/or the addition of prior information are expected to improve the linearity of the response. The potential for this type of imaging technique to serve as a surgical guide is highlighted.     

Fabrication of chitosan/poly(ε-caprolactone) composite hydrogels for tissue engineering applications

The aim of this study was to fabricate three-dimensional (3D) porous chitosan/poly(ε-caprolactone) (PCL) hydrogels with improved mechanical properties for tissue engineering applications. A modified emulsion lyophilisation technique was developed to produce 3D chitosan/PCL hydrogels. The addition of 25 and 50 wt% of PCL into chitosan substantially enhanced the compressive strength of composite hydrogel 160 and 290%, respectively, compared to pure chitosan hydrogel. The result of ATR–FTIR imaging corroborated that PCL and chitosan were well mixed and physically co-existed in the composite structures. The composite hydrogels were constructed of homogenous structure with average pore size of 59.7 ± 14 μm and finer pores with average size of 4.4 ± 2 μm on the wall of these larger pores. The SEM and confocal laser scanning microscopy images confirmed that fibroblast cells were attached and proliferated on the 3D structure of these composite hydrogels. The composite hydrogels acquired in this study possessed homogeneous porous structure with improved mechanical strength and integrity. They may have a high potential for the production of 3D hydrogels for tissue engineering applications.     

超声波在纺织工业中的应用

超声波工艺使用极高强度和频率的声波(通常高出人的听力范围--大于20kHz或2万cycles/s)对材料进行改性.     

Prevalence of β‐Lactamase Producing Escherichia coli from Retail Meat in Turkey

Extended spectrum β‐lactamase (ESBL) and plasmid‐mediated AmpC β‐lactamase (pAmpC) producing Escherichia coli have been shown to be present in humans and animals representing a significant problem worldwide. This study aimed to search the presence of ESBL and/or AmpC‐producing E. coli in retail meats (chicken and beef) in Turkey. A total of 88 β‐lactamase‐producing E. coli were isolated from chicken (n = 81/100) and beef meat (n = 7/100) samples and their susceptibility to several antimicrobials were tested using disc diffusion method. E. coli isolates were further characterized for their phylogenetic groups. β‐Lactamase encoding (bla_TEM, bla_SHV, bla_OXA, bla_CTX‐M, and bla_AmpC) and quinolone resistance genes (qnrA, qnrB, qnrS, qepA, and acc(6′)‐Ib‐cr) were also secreened by polymerase chain reaction (PCR). However, in regard to β‐lactamase genes, 84 of 88 isolates were positive for bla_CTX‐M‐1 (n = 39), bla_CTX‐M‐3 (n = 5), bla_CTX‐M‐15 (n = 4), bla_TEM‐1b (n = 2), bla_SHV‐12 (n = 1), bla_CTX‐M‐1/bla_TEM‐1b (n = 10), bla_CTX‐M‐1/bla_TEM‐1b/bla_SHV‐5 (n = 1), bla_CTX‐M‐1/bla_CMY‐2 (n = 1) and bla_TEM‐1b/bla_CMY‐2 (n = 6), bla_CTX‐M‐15/bla_SHV‐12 (n = 1), bla_CTX‐M‐15/bla_TEM‐1b (n = 1), bla_TEM‐1b/bla_SHV‐12 (n = 1)_, and bla_CMY‐2 (n = 12) genes. Resistance to cefuroxime (75.6% and 85.7%), nalidixic acid (89% and 85.7%), tetracycline (91.4% and 100%), streptomycin (40.2% and 100%), and trimethoprim‐sulfamethoxazole (36.6% and 85.7%) was observed among strains isolated from chicken and beef, respectively. However, all isolates were found to be susceptible to amikacin, imipenem, and cefepime. Resistance to ampicillin and cefoxitin was significantly linked to bla_CMY‐2 gene, while there was a significant correlation between CTX‐M type ESBL and antimicrobial resistance to cefuroxime and streptomycin (P < 0.05). The results of this study suggest that raw chicken retail meats are highly contaminated with ESBL‐producing E. coli implementing a great risk to human health in Turkey.     

A Preconcentration Procedure for Determination of Ultra-Trace Mercury (II) in Environmental Samples Employing Continuous-Flow Cold Vapor Atomic Absorption Spectrometry

New functionalized magnetic nanoparticles as solid-phase sorbent were prepared and investigated for extraction of ultra-trace amounts of mercury from environmental samples. The Fe₃O₄ magnetic nanoparticles functionalized with dithizone were characterized by Fourier transform infrared spectrometer. X-ray diffraction and scanning electron microscopy confirmed the size of nanoparticles. Effects of several factors on the extraction procedure were investigated. The optimized conditions were established to be 80 mg of polymer, 8.5 for solution pH, 5 min for adsorption time, 5 min for desorption time, 2 mL for HCl (0.1 mol L^?1)/ thiourea 0.05 % as the eluent, 500 mL for breakthrough volume, and without addition of salt. Under the optimal conditions, the limit of detection, maximum capacity, and preconcentration factor were 0.05 ng mL^?1, 0.557 mmol g^?1, and 250, respectively. Limit of quantification was in the range of 0.2–2 ng mL^?1 for various matrices. Accuracy and precision of the method were about ±2.0 and below 11.1 %, respectively. Finally, the present method has been successfully applied to mercury determination in table salt, green tea, vegetables, toothpaste, and water samples. The mercury content found in the real samples was from 0.6 to 15.74 ng mL^?1 without addition of mercury.     

Parametric Analysis of Dry Hydrocarbons on the Performance of Organic Rankine Cycle Improved by Working Fluid Reheating

In this paper, the performance of organic Rankine cycle with a two‐stage turbine and internal heat exchanger, considering different dry hydrocarbons as working fluid, has been analyzed. This thermodynamic analysis is done using Engineering Equation Solver version 8.379 software. The influence of working fluid reheating has been studied and the critical temperatures for the thermal and exergy efficiencies are determined. Results show that thermal and exergy efficiencies increase with working fluid reheating and also through a two‐stage turbine. RC‐318 is a good replacement for R‐236fa, R‐113 has a better efficiency than R‐236fa, R‐245fa, and iso‐butane and finally cyclohexane can achieve the highest efficiency. Although the maximum value of efficiencies for each one of working fluids are different, but all of these maximum values almost happen at a unique value of relative pressure of the cycle. The same result has been presented for variation of turbine inlet temperature.     

Investigation of the clean patterning possibilities on cotton socks through laser technology

The aim of this research is to reveal the effect of laser treatment at different resolutions (10, 20 and 30 dpi) and pixel times (80, 100 and 120 μs) on reactive dye uptake of cotton fabrics and the fastness values obtained. Yellowness index, Fourier Transform–infrared analysis, scanning electron microscopy analysis and bursting strength tests were applied to samples. The samples treated with laser were dyed in lighter shades than the untreated ones, with all three of the reactive dyes used in the experiments. In general, colour yield values decreased when the resolution and pixel time increased. However, no significant change was observed in washing, rubbing, light and perspiration fastness values. The possibilities of obtaining various patterns on cotton socks dyed with reactive dyes by laser treatment at different resolutions and pixel times were also investigated. According to the results, it was determined that if laser treatment was not applied to some parts of reactive dyed cotton socks, and 10 dpi 100 μs and 20 dpi 100 μs laser was applied to other parts of those socks, then it was possible to obtain patterns with different shades of the same colour on the socks. On the other hand, laser application after dyeing does not have a negative effect on fastness values. After determining the optimum conditions for the laser process, non-see-through tights were produced with cotton yarn on the front and polyester/elastane yarn on the back, and patterns were obtained by applying laser treatment before or after dyeing via sample scale industrial production.     

Improvement in Corrosion Resistance of Tantalum Oxide and Tantalum Oxide with Diethanolamine Sol–Gel Coated Magnesium Alloys

Protection of Metals and Physical Chemistry of Surfaces - In this study, corrosion resistance was developed to ensure that AZ91 Mg alloy remains stable in the body for longer periods. For this...