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Aviation and ground compressors are susceptible to the erosion of hard particles in the sandy environment, leading to lower performance and shorter service life of the equipment. Although many studies have been performed on this topic, current literature mainly focused on the steady ideal operating conditions of compressors. In this paper, particle motion behavior and erosion characteristics in the blade passage of a 3.5-stage axial compressor under actual service environment are investigated with the RANS numerical simulation method systematically. By comparing the particle trajectories, erosion rate density and other indicators, effect of particle diameter, particle mass concentration, compressor speed and inlet conditions on erosion characteristics are explored in detail. Results show that the value of erosion rate density on the blade pressure side is overall higher than the suction side. The erosion area and intensity of the rotors are generally more serious than stators, especially on the first rotor blade. With variation in particle size, particle diameter of 100 μm becomes the turning point to change the erosion trend of the blades. Moreover, the overall erosion rates increase linearly with increasing mass concentration of inhaled particles. However, its impact on the erosion position and morphology are not obvious. When the compressor speed increases from 6050 rpm to 6650 rpm, the eroded mass of R1 increases by 10.7%, and the casing erosion rate increases about 11 times. Compared with the winter condition, the overall erosion rate in summer increases by 62%. The results of this paper will provide a technology basis for the prediction on particle erosion behavior and formulation of operation and maintenance programs for aero engines and ground gas turbines under the actual service environment.

Background Parkinson’s disease (PD) is a neurodegenerative disorder with no absolute cure. The evidence of the involvement of gut microbiota in PD pathogenesis suggests the need to identify certain molecule(s) derived from the gut microbiota, which has the potential to manage PD. Osteocalcin (OCN), an osteoblast-secreted protein, has been shown to modulate brain function. Thus, it is of interest to investigate whether OCN could exert protective effect on PD and, if yes, whether the underlying mechanism lies in the subsequent changes in gut microbiota. Results The intraperitoneal injection of OCN can effectively ameliorate the motor deficits and dopaminergic neuronal loss in a 6-hydroxydopamine-induced PD mouse model. The further antibiotics treatment and fecal microbiota transplantation experiments confirmed that the gut microbiota was required for OCN-induced protection in PD mice. OCN elevated Bacteroidetes and depleted Firmicutes phyla in the gut microbiota of PD mice with elevated potential of microbial propionate production and was confirmed by fecal propionate levels. Two months of orally administered propionate successfully rescued motor deficits and dopaminergic neuronal loss in PD mice. Furthermore, AR420626, the agonist of FFAR3, which is the receptor of propionate, mimicked the neuroprotective effects of propionate and the ablation of enteric neurons blocked the prevention of dopaminergic neuronal loss by propionate in PD mice. Conclusions Together, our results demonstrate that OCN ameliorates motor deficits and dopaminergic neuronal loss in PD mice, modulating gut microbiome and increasing propionate level might be an underlying mechanism responsible for the neuroprotective effects of OCN on PD, and the FFAR3, expressed in enteric nervous system, might be the main action site of propionate.

It is now generally accepted that the extra-skeleton functionalities of bone are multifaceted. Its endocrine functions came first to light when it was realized that osteoblasts, the bone forming cells, maintain energy homeostasis by improving glucose metabolism, insulin sensitivity and energy expenditure through osteocalcin, a multipurpose osteokine secreted by osteoblasts. Recently, the emerging knowledge on the functional aspects of this osteokine expanded to properties including adult and maternal regulation of cognitive functions. Therapeutic potential of this osteokine has also been recently reported in experimental Parkinson’s disease models. This review highlights such findings on the functions of osteocalcin in the brain and emphasizes on exploring and analyzing much more in-depth basic and clinical studies.

The level of nicotinamide adenine dinucleotide (NAD) decreases in Parkinson's disease (PD), and its reduction has been reported to be involved in many age-associated neurodegenerative pathologies. Thus, we investigated whether NAD replenishment is beneficial in a 6-hydroxydopamine (6-OHDA)-induced mouse model of PD. Preinjection with NAD in the striatum ameliorated motor deficits and dopaminergic neuronal damage in the substantia nigra and striatum of a mouse model of PD. Moreover, preincubation with NAD protected PC12 cells against the loss of cell viability, morphological damage, oxidative stress and mitochondrial dysfunction caused by 6-OHDA. These results add credence to the beneficial role of NAD against parkinsonian neurodegeneration in mouse models of PD, provide evidence for the potential of NAD for the prevention of PD, and suggest that NAD prevents pathological changes in PD via decreasing mitochondrial dysfunctions.

Osteoblasts derived osteocalcin (OCN) is recently reported to be involved in dopaminergic neuronal development. As dopaminergic neuronal injury in the substantia nigra (SN) is a pathological hallmark of Parkinson's disease (PD), we investigated whether OCN could exert protective effects on 6-hydroxydopamine (6-OHDA)-induced PD rat model. Our data showed that the OCN level in the cerebrospinal fluid (CSF) in PD rat models was significantly lower than that in controls. Intervention with OCN could improve the behavioral dysfunction in PD rat models and reduce the tyrosine hydroxylase (TH) loss in the nigrostriatal system. In addition, OCN could inhibit the astrocyte and microglia proliferation in the SN of PD rats. In vitro studies showed that OCN significantly ameliorated the neurotoxicity of 6-OHDA through the AKT/GSK3β signaling pathway. In summary, OCN plays a protective role against parkinsonian neurodegeneration in the PD rat model, suggesting a potential therapeutic use of OCN in PD.

As cars become more and more quiet the sound quality of rotary components such as car compressor becomes more important in the customer’s subjective perception of passenger car quality. This needs a new evaluation method which is not only the traditional method like sound pressure level but also Psychoacoustic Metrics to focus the specification of component sounds. This paper on one hand analyzed one car’s abnormal noise reason through the tests, found the main problem frequency band of the compressor, and on the other hand studied the compressor’s psychoacoustic metrics. In this paper the countermeasure of solving this problem was also given, and then noise level and psychoacoustic parameters are compared. Both objective evaluation and subjective evaluation showed that the compressor with the solution not only reduced the sound pressure level, but also improved the car sound quality greatly.

The efficacy of oral hydration in the prevention of contrast-induced nephropathy in patients undergoing elective coronary intervention is unclear.A total of 120 patients were randomly assigned to three groups. Group A (n = 40) received intravenous hydration before and after coronary angiography or angioplasty. Group B (n = 40) received oral tap water before and after the procedures, whereas group C (n = 40) received only postprocedural drinking water. Levels of serum creatinine and urea nitrogen were measured before, 12 hours after, 2 and 3 days after the coronary angiography or angioplasty.: There was no statistically significant difference in the age, sex, baseline renal function and the volume of contrast medium used during the coronary procedures among the three groups (P0.05).There was no statistically significant difference in the mean serum creatinine or urea nitrogen among the three groups 12 hours, and 3 days after the coronary procedures ( P0.05).The incidence of contrast-induced nephropathy in group A, B and C was 5.0% (2/40), 7.5% (3/40) and 5.0% (2/40), respectively (P = 0.86). Renal function in the seven patients who experienced contrast-induced nephropathy recovered within a week following rehydration treatment.Pre- and post-procedural oral hydration was as effective as intravenous rehydration in the prevention of contrast-induced nephropathy in patients undergoing coronary angiography or angioplasty.

Cross Correlation Function Amplitude Vector(CorV) is a method of damage detection which is based on random vibration .In this paper, CorV is introduced in the damage detection of historic timber structure according to the characteristics of structure and damage.Meanwhile,the research has been done. CorV of structural damage before and after the change has been expressed that is based on Cross Correlation function amplitude Vector Criterion(CVAC) .Results show that there is a remarkable decrease of CVAC among the CorVs between damaged and intact structures.Damage locations can be determined through the relative change of CorVs which is before or after the damage of the structure . A basis can be provided for the damage of buildings and the ancient structure protection through this paper.

This paper studies several factors that affect the reliability of established structures .The theory of Data Mining is introduced into this paper as a new method to study the evaluation of established structures. New information is ultimately mined from “Data Sea” filed up in existed structures. According to the Chinese Structure Code and engineering experience, the factors affecting the reliability of structures are properly qualified as input parameters. This paper mainly researches with engineering structural examples on the theory of fuzzy cluster, which belong to the field of Data Mining. According to the analysis of the methods， it is found that the method put forward in this paper is practicable, reliable and effective.

Five different exhaust configurations were installed on the vehicle respectively and binaural sound signals at rear left passenger under ten operating conditions were recorded as subjective evaluation samples. Paired comparison method was introduced to subjectively evaluate the annoyance of these sound signals. Evaluation data was studied using Ranking-based and Bradley-Terry model fitting approach respectively and the correlation analysis showed excellent consistency between them. Accordingly interior subjective annoyance of different exhaust configurations was obtained and the best one was identified.

To investigate the knowledge and attitudes of practicing nurses on comfort care for hospitalized patients, a survey was conducted in 311 registered nurses from a major teaching hospital. A total of 212 (68.1%) of the participants showed an adequate knowledge of comfort care. Participants who had 6 years or more working experience returned a higher mean scores on physiological and psychological aspects of comfort care (P