The Chemical Composition and Nitrogen Distribution of Chinese Yak (Maiwa) Milk

The paper surveyed the chemical composition and nitrogen distribution of Maiwa yak milk, and compared the results with reference composition of cow milk. Compared to cow milk, yak milk was richer in protein (especially whey protein), essential amino acids, fat, lactose and minerals (except phosphorus). The contents of some nutrients (total protein, lactose, essential amino acids and casein) were higher in the warm season than in the cold season. Higher ratios of total essential amino acids/total amino acids (TEAA/TAA) and total essential amino acids/total non essential amino acids (TEAA/TNEAA) were found in the yak milk from the warm season. However its annual average ratio of EAA/TAA and that of EAA/NEAA were similar to those of cow milk. Yak milk was rich in calcium and iron (p < 0.05), and thus may serve as a nutritional ingredient with a potential application in industrial processing

Altered Brain Fraction Amplitude of Low Frequency Fluctuation at Resting State in Patients With Early Left and Right Bell’s Palsy: Do They Have Differences?

Purpose: Bell’s palsy refers to acute idiopathic unilateral facial nerve palsy. It is a common disorder of the main motor pathway to the facial muscles. This study aimed to investigate the abnormal fraction amplitude of low frequency fluctuation (fALFF) of the brain in patients with early left and right Bell’s palsy.Materials and Methods: Sixty-seven patients (left 33, right 34) and 37 age- and sex-matched healthy controls underwent resting-state functional magnetic resonance imaging (R-fMRI) examination. The fALFF values were measured from all subjects and were compared among the left palsy, right palsy, and control groups. Then, correlations between the Toronto Facial Grading System (TFGS) scores of the patients and the fALFF values of abnormal brain regions were analyzed.Results: Significant group differences in fALFF values among the three groups were observed mainly in the cerebral cortical, subcortical, and deep gray matter regions. Compared with the right Bell’s palsy group, the left Bell’s palsy group showed significantly decreased fALFF values in the left temporal pole of the superior temporal gyrus (TPOsup), right supramarginal, left and right middle cingulate cortex (MCC), left superior frontal gyrus (SFG), and left precentral gyrus (PreCG), and increased fALFF values were observed in the right SFG and PreCG. Furthermore, altered fALFF values correlated positively with the TFGS scores in the left superior TPO, bilateral MCC, and right PreCG, and correlated negatively with the TFGS scores in the right SFG of the left Bell’s palsy group. Altered fALFF values correlated positively with the TFGS scores in the bilateral MCC and right PreCG and correlated negatively with the TFGS scores in the left superior TPO and SFG of the right Bell’s palsy group.Conclusion: Regulatory mechanisms seem to differ between patients with left and right early Bell’s palsy. The severity of the disease is associated with these functional alterations

Experimental Investigations of Expansion Strength of Hydraulic Expansion Joints Interconnecting Tube and Fins Heat Exchanger

As a high expansion strength corresponds to a high heat transfer efficiency, this study investigated the expansion strength of an air-conditioning heat exchanger jointed by hydraulic expansion. A device that would be reliable and adaptable to different types of tubes and fins was designed and developed for testing hydraulic expansion. The device was used to perform a non-pulsating hydraulic expansion experiment on samples comprising tubes and fins to determine the hydraulic pressure range. The expansion strength was tested by performing tensile tests to evaluate the pull-out force at different bulging zones of the same sample with the selected hydraulic pressure. A series of pulsating hydraulic expansion experiments were performed on the joints of tubes and fins with different pulsating amplitudes and frequencies. Tensile tests were performed on the pulsating hydraulic expansion samples to study the influence of the pulsation parameters on the pull-out force. When the amplitude was fixed, an increase in frequency led to uniform expansion in the exchanger. This indicates that joint expansion in tubes and fins results in a more reliable heat exchanger performance

Experimental Investigations of Expansion Strength of Hydraulic Expansion Joints Interconnecting Tube and Fins Heat Exchanger

As a high expansion strength corresponds to a high heat transfer efficiency, this study investigated the expansion strength of an air-conditioning heat exchanger jointed by hydraulic expansion. A device that would be reliable and adaptable to different types of tubes and fins was designed and developed for testing hydraulic expansion. The device was used to perform a non-pulsating hydraulic expansion experiment on samples comprising tubes and fins to determine the hydraulic pressure range. The expansion strength was tested by performing tensile tests to evaluate the pull-out force at different bulging zones of the same sample with the selected hydraulic pressure. A series of pulsating hydraulic expansion experiments were performed on the joints of tubes and fins with different pulsating amplitudes and frequencies. Tensile tests were performed on the pulsating hydraulic expansion samples to study the influence of the pulsation parameters on the pull-out force. When the amplitude was fixed, an increase in frequency led to uniform expansion in the exchanger. This indicates that joint expansion in tubes and fins results in a more reliable heat exchanger performance

Estimation of the postmortem interval using chromatographic fingerprints of volatile organic compounds from muscle

Estimation of the postmortem interval (PMI) is a crucial task in the field of forensic pathology and has unfortunately not been properly resolved. In this study, we analyzed volatile organic compounds (VOCs) in rat muscle samples collected at different PMIs and studied the feasibility of muscle VOC fingerprinting as a new method for PMI estimation. In total, 110 rats were sacrificed and stored at a constant temperature (25°C). Rat skeletal muscle samples were collected at 0–10-day postmortem, and then the VOCs were determined using a method of headspace solid-phase microextraction coupled with gas chromatography-mass spectrometry. The correlations between the VOCs (species and quantities) and PMIs were carefully analyzed and standard muscle VOC fingerprints at 25°C were established for different PMIs. To further test the accuracy of muscle VOC fingerprinting as a method for PMI estimation, ten additional rats with known PMIs were studied. We identified 15 kinds of VOCs and the number of VOC species increased with the PMI. The total peak areas of the VOCs increased significantly with the postmortem day (adjusted R2 = 0.96–0.97). The mean error of the VOC fingerprinting for PMI estimation was 0.5 days and the mean relative error was 8.33%. We concluded that muscle VOC fingerprinting combining the use of VOC species and peak areas is accurate and effective and could be used as an alternative approach for PMI estimation in forensic practice. Although the preliminary results are encouraging, further studies in human cadavers under real case conditions are needed

Photovoltaic Devices Employing Ternary PbSxSe1-x Nanocrystals

We report solar cells based on highly confined nanocrystals of the ternary compound PbSxSe1-x. Crystalline, monodisperse alloyed nanocrystals are obtained using a one-pot, hot injection reaction. Rutherford back scattering and energy filtered transmission electron microscopy suggest that the S and Se anions are uniformly distributed in the alloy nanoparticles. Photovoltaic devices made using ternary nanoparticles are more efficient than either pure PbS or pure PbSe based nanocrystal devices

Failure Analysis of Hydraulic Expanding Assembled Camshafts Using BP Neural Network and Failure Tree Theory

Due to the complex and changeable working environment of assembled camshafts using tube hydroforming (THF) technology, the manifestations of failure, the causes of failure and the preventive measures for these failures are a major concern. Therefore, in view of this new connection technology for assembled camshafts, it is important to put forward a prediction and evaluation method of failure for hydraulic expanding assembled camshafts. In this study, an isometric-trilateral profile cam was used to complete the hydroforming connection with the hollow shaft (tube) under different hydraulic pressures. Orthogonal torsion experiment and laser measurement experiment were performed. Finite element analysis was carried out using ABAQUS 6.14 software, and relevant research data were obtained. A more accurate BP neural network model was constructed to predict the main failure factors of assembled camshafts. The failure manifestations of assembled camshafts are displayed by the experiment from the microscopic perspective. The causes of failure are analyzed by using the minimum cut set in the failure Tree (FT) theory. The effect of basic causes on the subsystems is analyzed, and the weight distribution of the main events in the FT is given. Finally, the specific measures to prevent failure are proposed from a macro perspective. The research is of great significance to study the failures of assembled camshafts in service to further the production, manufacturing, failure prevention, faults monitoring and performance improvement of assembled camshafts in the engine industry

Degradation of 1-alkyl-3-methylimidazolium tetrafluoroborate in an ultrasonic zero-valent zinc and activated carbon micro-electrolysis system

Abstract Increased attention has been given to the removal of ionic liquids (ILs) from natural water environments. In this work, 5 kinds of 1-alkyl-3-methylimidazoliumtetrafluoroborate ([Cnmim][BF4] (n = 2, 4, 6, 8, 10)) ILs were degraded in an ultrasonic zero-valent zinc (ZVZ) and activated carbon (AC) micro-electrolysis system. Optimization of degradation conditions and the degradation levels were studied by high performance liquid chromatography, the surface morphology of the ZVZ and AC changed before and after the reaction were observed by scanning electron microscope. The degradation intermediates were detected by gas chromatography- mass spectrometry and ion chromatography, and inferred the degradation pathway. The degradation effect of [C4mim][BF4] was best with ultrasonic assistance, pH 3 and an AC/ZVZ ratio of 1:1. The degradation of [Cnmim][BF4] in aqueous solution exceeded 91.7% in 120 min, and the mineralization level exceeded 88.9%. The surface of smooth and dense ZVZ particles became loose flocculent and the porous surface of AC became larger and rougher after reaction. The degradation pathway suggested that the imidazolium ring was sulfurized or oxidized, and then the ring was opened to form N-alkyl formamide and N-methyl formamide. ZVZ/AC micro-electrolysis combined with ultrasonic irradiation is an effective method to remove ILs, which provides new insight into IL degradation

Protein composition of yak milk

The protein composition of 24 individual Maiwa yak milk samples that were collected in the Sichuan province of China was determined by reversed-phase high-performance liquid chromatography. Yak milk differed from cow milk by its high concentration of total proteins (46.2–58.4 g·L−1), total casein (40.2 g·L−1 on average) and the proportion of individual caseins. The high content of β-casein (more than 45%) and consequently the lower proportion of αs-casein (about 40%) together with a small increase in κ-casein (15%) appear to make this milk more favorable for infant nutrition as used by the Tibetan nomads. Also, the whey proteins, β-lactoglobulin and serum albumin, showed similarities in centesimal composition with the homologous cow whey proteins. However, this initial study on yak milk proteins has highlighted the lack of knowledge in the literature and underlines that much research is required to optimize the utilization of all components of this milk for people living in extreme climatic environments