An investigation on the impact fatigue characteristics of valve leaves for small hermetic reciprocating compressors in a new automated test system

This paper presents an investigation on the impact fatigue characteristics of valve leaves that are prevalently used in hermetic reciprocating compressors especially for the household type refrigerators. A unique automated impact fatigue test system has been designed and produced, which enables to carry out impact fatigue tests of the compressor valve leaves under the desired impact velocities. The test system incorporates a noncontact actuation, a data acquisition system and an acoustic‐based damage detection technique, which continuously monitors the health of the structure. The damage detection system allows parametrical investigation on the impact fatigue life by detecting any possible damage and automatically terminating the test. The investigation relates the impact fatigue lifetime of the valve leaves with the impact velocity, asymmetrical impact, operation temperature, material type (carbon strip steel, stainless strip steel and new stainless strip steel grade) and tumbling operation duration. The observations show that the cracks have initiated from the edges of the valve leaf where is in contact with the valve plate. Subsequently, the cracks initially have propagated in the radial direction inwards the center of the impact area. Various failure cases have been resulted in by either a single crack or inter‐related multiple cracks. Microscopic and metallographic observations have been performed on the specimens to enhance the understanding of the damage mechanisms. The investigation and introduced test system guide the design optimization of the valve leaves in terms of compressor performance due to the energy consumption and lifetime of the valve leaf.     

A survey of the occurrence and properties of methicillin‐resistant Staphylococcus aureus and methicillin‐resistant Staphylococcus intermedius in water buffalo milk and dairy products in Turkey

Antimicrobial resistance, β‐lactamase activity and mecA gene of Staphylococcus aureus and Staphylococcus intermedius isolated from raw water buffalo milk and dairy products in Turkey were determined. All strains showed resistance to at least one antibiotic but none was resistant to vancomycin. Of the 97 S. aureus and 35 S. intermedius strains, 9 (9.2%) and 2 (5.7%) were resistant to oxacillin and harboured mecA gene. β‐lactamase activity of 13.4% and 5.7% of S. aureus and S. intermedius strains was positive, respectively. Overall, 2.5% and 0.55% of the samples were contaminated with methicillin‐resistant S. aureus and S. intermedius, respectively.     

Oxygen permeability of macrocrystalline paraffin wax and relevance to wax coatings on natural corks used as wine bottle closures

The oxygen permeability of a commercial macrocrystalline paraffin wax was determined. This permeability figure and diffusion theory were used to calculate the theoretical ingress of oxygen through the paraffin coating of a cork used as a bottle closure. We wanted to ascertain whether macrocrystalline paraffin wax coatings used on corks could be permeable enough to allow oxidation of wine. We also employed electron microscopy to show the spread of coatings on waxed corks before and after insertion inside a bottle. Our calculations indicated that oxygen permeation along the length of paraffin coating on a cork closure would not allow ingress of sufficient oxygen to cause oxidation of wine during storage.     

Boldine provides protective effect against nephrotoxicity induced by cisplatin in Wistar rats: Role of oxidative stress,inflammation and caspase-3

Side effects of cisplatin, especially dose-dependent nephrotoxicity, are major factors limiting its use in cancer. Boldine ((S)-2, 9-dihydroxy-1, 10-dimethoxy-aporphine) is a natural alkaloid known for its strong antioxidant activity present in leaves/bark of boldo tree (Peumus boldus Molina), a native tree in Chile. Here, we aimed to investigate the nephroprotective effect of boldine and its underlying mechanisms on cisplatin-induced rat renal injury. Thirty Wistar albino rats divided into 5 groups (Control, Cis, Bold.40, Cis + Bold.20, Cis + Bold.40 groups) were used. Rats received boldine (20 or 40 mg/kg/day), or vehicle (saline) intraperitoneal for 14 days and a single dose cisplatin (7 mg/kg, ip) was applied on the 10th day to induce nephrotoxicity. Rats and kidney tissue were weighed to determine kidney index. Blood urea nitrojen (BUN) and creatinine levels, the amount of thiobarbituric acid reactive substances (TBARS, an index of lipid peroxidation), superoxide dismutase (SOD), glutathione peroxidase (GPx) enzyme activities and tumor necrosis factor alpha (TNF-α) levels were measured and histopathologic examination was performed. Inducible nitric oxide synthase (iNOS) and caspase-3 expressions were detected immunohistochemically. Nephrotoxicity induced by cisplatin was apparent by elevated levels of BUN, creatinine, kidney index, TBARS and TNF-α, and decreased body weight, SOD and GPx enzyme levels. Pretreatment with boldine protected the renal function at both boldine doses by fixing the renal damage markers, oxidative stress, caspase-3 and iNOS expression. Histopathological findings supported biochemical findings. Taken together these findings indicate that boldine has promising protective effect against cisplatin nephrotoxicity by improving oxidative stress, inflammation, histopathological alterations and by alleviating caspase 3 expression.     

EFFECT OF PENTOSANASE ON DOUGH AND BREAD PROPERTIES PRODUCED BY DIFFERENT TYPES OF FLOURS

ABSTRACT

The effects of pentosanase at different doses (20, 60 and 100 ppm) on physical dough properties and bread quality were studied using three types of wheat flours. Flour A was a regular bread flour, flour B had a high hardness ratio and protein content, and flour C was prepared from the same blend of flour A but had a high extraction ratio. Regarding farinograph data, water absorption values of the high extraction (86%) flour C and high hardness (65%) blend flour B increased with introduction of pentosanase. Extensibility values of the flours increased moderately with pentosanase addition, while resistance and energy values decreased. The volume of breads made with flours C and B decreased upon addition of pentosanase. But loaf volume of breads prepared with regular bread flour A with 50% hardness and 76% extraction rate increased with high levels of pentosanase addition. In conclusion, flour A as a regular bread flour gave satisfactory results with pentosanase supplementations, whereas the harder‐blend (65%) and higher‐extraction‐rate (85%) flours from the same cultivars did not.

PRACTICAL APPLICATIONS

Pentosanase addition was more effective on soluble pentosans than on insoluble ones. Because of these effects, it enhanced the bread‐making properties of regular flour more effectively than those of the high‐extraction and harder‐blend flours of the same cultivars.

     

复合球体生产海绵铁过程中还原剂膨润土钠含量和反应温度的作用

近年来,添加还原剂的复合球体铁生产逐步代替传统的铁生产.在高温下,加入适当比例的还原剂,在其熔化过程中产生海绵铁.通过确定化学成分和适当的反应温度可以获得产品,而球体结构在生产中产生的元素直接影响产品的质量.本研究将海绵铁矿石精矿(等级)和还原剂(焦煤尘和膨润土钠)按一定比例混合制备复合球体样品,研究了膨润土钠还原剂的...     

Diagnostic and prognostic significance of the lymphocyte/C-reactive protein ratio,neutrophil/lymphocyte ratio,and D-dimer values in patients with COVID-19

In this study, our aim was to examine the diagnostic and prognostic significance of lymphocyte/C-reactive protein ratio (LCR), neutrophil/lymphocyte ratio (NLR) and D-dimer parameters in COVID-19 infection. The LCR, NLR, neutrophil count, mean platelet volume (MPV), C-reactive protein (CRP), and D-dimer parameters were evaluated retrospectively. This was a retrospective cohort study with 1000 COVID-19 positive and 1000 healthy control groups, all over the age of 18 years. Odds ratio (OR) and 95% confidence interval (CI) values were calculated for each parameter found to be statistically significant in the univariate and multivariate logistic regression models. Herein, 127 (12.7%) of the COVID-19⁺ patients, whose data was included in this study, died. The neutrophil, MPV, CRP, D-dimer, and NLR values were higher in the COVID-19⁺/deceased group than in the COVID-19⁺/alive and control groups (p < 0.001, p < 0.001, p < 0.001, p < 0.001, p < 0.001). The lymphocyte and LCR values were lower in the COVID-19⁺/deceased group than in the COVID-19⁺/alive and control groups (p < 0.001, p < 0.001). Variables with statistically significance in predicting COVID-19 infection were lymphocyte, LCR, D-dimer, NLR, CRP, MPV, PLT, and neutrophil values. Statistically significant variables in predicting mortality due to COVID-19 were LCR, CRP, NLR, lymphocyte, D-dimer, neutrophil, and MPV values. A low LCR and high NLR are associated with the presence, prognosis, and mortality due to COVID-19. LCR and NLR parameters can thus be used in clinical monitoring to reduce morbidity and mortality rates.     

Hydrophone Arrays Assembled from PZT Ceramic Foams

A 3 × 3 hydrophone array for low frequency applications was constructed from reticulated PZT ceramic foams. The hydrophone array was tested for receiving sensitivity and compared with single element PZT-air and dense PZT hydrophones. The composite array showed a flat response in the 20 kHz–100 kHz frequency range while the single element hydrophone displayed broadening radial resonance around 50 kHz. The flat, broadband response indicates that the radial resonance is suppressed by both porous nature of the PZT-air composites and the array construction of the hydrophone. The sensitivity of the array hydrophone was –205 dB re 1 Vμ Pa^?1.     

OCCURRENCE OF ESCHERICHIA COLIO157:H7/O157, LISTERIA MONOCYTOGENES AND SALMONELLA SPP. IN BEEF SLAUGHTERHOUSE ENVIRONMENTS, EQUIPMENT AND WORKERS

Escherichia coli O157/O157:H7, Listeria monocytogenes and Salmonella spp. are major foodborne pathogens and the emergence of these pathogens has been reported in many countries. The aim of this study was to investigate contamination of the beef slaughterhouse environment, equipment and workers with E. coli O157/O157:H7, L. monocytogenes and Salmonella spp. For this study, 500 swab samples were taken from 19 different points in five privately owned slaughterhouses, their periphery, slaughterhouse equipment and slaughterhouse employees. The presence of E. coli O157:H7/O157, L. monocytogenes and Salmonella spp. was determined with the application of the immunomagnetic separation method. Our study showed that the swabs taken from the five slaughterhouses contained E. coli O157:H7 in the environment, equipment, abattoir workers and water with a frequency 0.31, 1, 1.42 and 0%, respectively; while E. coli O157 was evident in the environment, equipment, abattoir workers and water with a ratio of 15, 10, 10 and 0%, respectively; L. monocytogenes was detected in the environment, equipment, abattoir workers and water at a ratio of 4.37, 15, 5.71 and 0%, respectively; and Salmonella spp. occurrence in the environment, equipment, abattoir workers and water at a ratio of 3.43, 16, 11.42, and 0%, respectively. Implementing hazard analysis critical control point principles in work procedures would definitely reduce the gross contamination occurring in abattoirs.

PRACTICAL APPLICATIONS

This study has revealed the effect of personnel and equipment on the contamination routes of E. coli O157:H7, Listeria monocytogenes and Salmonella spp. in meat in slaughterhouses and showed that especially L. monocytogenes and Salmonella spp. may pose a higher risk than E. coli O157:H7 in slaughterhouses.     

Selective online solid-phase extraction of copper using p-morpholino-methylcalix[4]arene appended silica-based column

ABSTRACT

This study deals with investigation of selectivity of p-morpholino-methylcalix[4]arene appended silica from a group of metal ions having similar charge and radii. The values of distribution ratio revealed that modified silica possess higher selectivity for Cu²⁺. In addition, relative selectivity coefficients of modified silica were found to be 24.1, 13.8, 8.6 and 4.01 for Cu²⁺/Ni²⁺, Cu²⁺/Co²⁺, Cu²⁺/Cd²⁺, Cu²⁺/Pb²⁺, respectively. The maximum adsorption capacity was 1.5 mmolg^?1. The reusability data suggested no any loss of adsorption capacity of this material up to 10 cycles. The developed material was also applied for determination of copper in lake water samples with satisfactory results.