凉水塔风机断轴原因分析

针对凉水塔风机在连续断轴事故进行现场分析和理论分析，找出风机断轴的原因，采取了针对性措施，避免了风机的断轴事故再次发生。     

1107-JA半贫液泵断轴原因分析与对策

针对断轴特征,通过对半贫液泵进行综合分析,找出其断轴原因,并制定出解决断轴的对策.     

多级离心泵泵轴破坏原因分析及措施

针对离心泵断轴事故进行了断轴断面、结构和疲劳强度分析,找出了事故原因,提出相应的改进措施,取得了一定效果。     

螺旋输送机的断轴原因分析及改造

针对某PTA装置中的螺旋输送机突然发生的断轴情况,分析造成断轴的原因并提出改造方案。     

SP238计量泵断轴故障分析

就德国Ｂａｒｍａｇ公司产ＳＰ２３８纺丝机在生产过程中易发生的计量泵断轴现象进行了８个方面原因分析，提出了预防断轴的８条措施。     

150FB-35型离心泵断轴的原因分析与改进措施

150FB-35型离心泵在使用中断轴频繁,严重威胁安全生产。在实践中通过不断摸索和总结,认为断轴原因主要是泵轴设计不合理、机组轴心不重合、轴承造型不当、泵的出水管道安装不合理。针对以上情况采取了重新设计加工泵轴、对机组重新找正、轴承改型、泵的出水管道增设伸缩装置等改造措施和相应的一些预防措施,实施后杜绝了断轴事故的发生。     

克劳斯硫黄回收装置液硫泵断轴原因分析与改进建议

某天然气净化厂克劳斯硫黄回收装置液硫泵为长轴液下泵，使用中频繁出现断轴故障。通过对断轴进行化学成分分析、宏观和微观形貌分析、非金属夹杂物评定，并从泵的结构、操作运行和配套液硫池设计几个方面综合分析，认为当泵因滑动轴承磨损等原因出现偏心旋转时，轴受到扭转与弯曲载荷是断轴的主因，轴内非金属夹杂物多、启机瞬间扭矩大是导致断轴的次因，装置减产和配套液硫池设计不合理致使泵长时间处于低流量工况运行也对断轴有影响。从优化工艺操作、状态监测、改进启动方式、材料控制和泵的改型等方面提出了建议措施。     

炼油焦化装置高压离心水泵轴断裂失效分析

某企业高压离心水泵发生断轴事故,对该高压水泵断轴进行材料化学成分、断口宏观形貌、金相组织以及断口腐蚀产物能谱等检验分析。结果表明,造成此次高压水泵断轴事故的主要原因是介质水中含有硫和氯,并在水泵的出口处聚集浓缩,使泵轴产生腐蚀凹坑,从而引起裂纹萌生,最终导致疲劳裂纹扩展,使泵轴发生断裂失效。     

强自吸双吸循环水泵故障多发的原因分析与对策

泵轴的断裂原因涉及操作环境、材质、轴负荷、汽蚀以及装配质量等多个方面,其中之一或更多方面的共同作用都会导致泵轴在运行时断裂,通过对循环水场两台双吸泵的断轴故障原因分析,提出改造措施,消除了断轴现象,保证了水泵的长周期安全运行。     

皮带输送机电机断轴原因分析与改进

皮带输送机运行130小时后出现断轴故障,通过对皮带机启动方式、传动结构、轴加工工艺、材质热处理情况分析出断轴原因,提出改进方案并实施成功。     

Alginate-g-PNIPAM-Based Thermo/Shear-Responsive Injectable Hydrogels: Tailoring the Rheological Properties by Adjusting the LCST of the Grafting Chains

Graft copolymers of alginate backbone and N-isopropylacrylamide/N-tert-butylacrylamide random copolymer, P(NIPAM_x-co-NtBAM_y), side chains (stickers) with various NtBAM content were designed and explored in aqueous media. Self-assembling thermoresponsive hydrogels are formed upon heating, in all cases, through the hydrophobic association of the P(NIPAM_x-co-NtBAM_y) sticky pendant chains. The rheological properties of the formulations depend remarkably on the NtBAM hydrophobic content, which regulates the lower critical solution temperature (LCST) and, in turn, the stickers’ thermo-responsiveness. The gelation point, T_gel, was shifted to lower temperatures from 38 to 20 °C by enriching the PNIPAM chains with 20 mol % NtBAM, shifting accordingly to the gelation temperature window. The consequences of the T_gel shift to the hydrogels’ rheological properties are significant at room and body temperature. For instance, at 37 °C, the storage modulus increases about two orders of magnitude and the terminal relaxation time increase about 10 orders of magnitude by enriching the stickers with 20 mol % hydrophobic moieties. Two main thermo-induced behaviors were revealed, characterized by a sol–gel and a weak gel–stiff gel transition for the copolymer with stickers of low (0.6 mol %) and high (14, 20 mol %) NtBAM content, respectively. The first type of hydrogels is easily injectable, while for the second one, the injectability is provided by shear-thinning effects. The influence of the type of media (phosphate buffer (PB), phosphate-buffered saline (PBS), Dulbecco’s modified Eagle’s medium (DMEM)) on the hydrogel properties was also explored and discussed. The 4 wt % NaALG-g-P(NIPAM₈₀-co-NtBAM₂₀)/DMEM formulation showed excellent shear-induced injectability at room temperature and instantaneous thermo-induced gel stiffening at body temperature, rendering it a good candidate for cell transplantation potential applications.     

Interphases in the Adhesive Bonding of Fluoropolymers

Strong and durable adhesive bonds may be made between polytetrafluoroethylene (PTFE) and either cyanoacrylate (CA) or epoxy adhesives, if the PTFE surface is modified by the use of a “primer” such as triphenylphosphine (TPP) or diaminodiphenylmethane (DDM). The primer mixes with the PTFE surface, and the modified surface is then capable of forming an interphase, tens to hundreds of nanometers thick, where interpenetration of the adhesive and adherend occurs. Using CA adhesives, PTFE/CA/PTFE block compression shear bond strength (ASTM D4501-85) of over 10 MPa can be achieved, with failure occurring cohesively. Initial work with epoxy adhesives indicates that the use of DDM primer gives adhesive bonds comparable in strength with those produced by modification of the fluoropolymer surface by sodium naphthalenide.     

On the several molecules and nanostructures of water

This paper investigates the water molecule from a variety of viewpoints. Water can involve different isotopes of Hydrogen and Oxygen, it can form differently shaped isomer molecules, and, when frozen, it occupies space differently than most other substances do. The tool for conducting the investigation of all this is called 'Algebraic Chemistry'. This tool is a quantitative model for predicting the energy budget for all sorts of changes between different ionization states of atoms that are involved in chemical reactions and in changes of physical state. The model is based on consistent patterns seen in empirical data about ionization potentials, together with rational scaling laws that can interpolate and extrapolate for situations where no data are available. The results of the investigation of the water molecule include comments, both positive and negative, about technologies involving heavy water, poly water, Brown's gas, and cold fusion.     

Exploring the Impact of the Microbiome on Neuroactive Steroid Levels in Germ-Free Animals

Steroid hormones are essential biomolecules for human physiology as they modulate the endocrine system, nervous function and behaviour. Recent studies have shown that the gut microbiota is directly involved in the production and metabolism of steroid hormones in the periphery. However, the influence of the gut microbiota on levels of steroids acting and present in the brain (i.e., neuroactive steroids) is not fully understood. Therefore, using liquid chromatography–tandem mass spectrometry, we assessed the levels of several neuroactive steroids in various brain areas and the plasma of germ-free (GF) male mice and conventionally colonized controls. The data obtained indicate an increase in allopregnanolone levels associated with a decrease in those of 5α-androstane-3α, 17β-diol (3α-diol) in the plasma of GF mice. Moreover, an increase of dihydroprogesterone and isoallopregnanolone in the hippocampus, cerebellum, and cerebral cortex was also reported. Changes in dihydrotestosterone and 3α-diol levels were also observed in the hippocampus of GF mice. In addition, an increase in dehydroepiandrosterone was associated with a decrease in testosterone levels in the hypothalamus of GF mice. Our findings suggest that the absence of microbes affects the neuroactive steroids in the periphery and the brain, supporting the evidence of a microbiota-mediated modulation of neuroendocrine pathways involved in preserving host brain functioning.     

Exploring the Role of Different Neonatal Nutrition Regimens during the First Week of Life by Urinary GC-MS Metabolomics

In this study, a gas-chromatography mass spectrometry (GC-MS) metabolomics study was applied to examine urine metabolite profiles of different classes of neonates under different nutrition regimens. The study population included 35 neonates, exclusively either breastfed or formula milk fed, in a seven-day timeframe. Urine samples were collected from intrauterine growth restriction (IUGR), large for gestational age (LGA), and appropriate gestational age (AGA) neonates. At birth, IUGR and LGA neonates showed similarities in their urine metabolite profiles that differed from AGA. When neonates started milk feeding, their metabolite excretion profile was strongly characterized by the different diet regimens. After three days of formula milk nutrition, urine had higher levels of glucose, galactose, glycine and myo-inositol, while up-regulated aconitic acid, aminomalonic acid and adipic acid were found in breast milk fed neonates. At seven days, neonates fed with formula milk shared higher levels of pseudouridine with IUGR and LGA at birth. Breastfed neonates shared up-regulated pyroglutamic acid, citric acid, and homoserine, with AGA at birth. The role of most important metabolites is herein discussed.     

How Parkinsonian Toxins Dysregulate the Autophagy Machinery

Since their discovery, Parkinsonian toxins (6-hydroxydopamine, MPP+, paraquat, and rotenone) have been widely employed as in vivo and in vitro chemical models of Parkinson’s disease (PD). Alterations in mitochondrial homeostasis, protein quality control pathways, and more recently, autophagy/mitophagy have been implicated in neurotoxin models of PD. Here, we highlight the molecular mechanisms by which different PD toxins dysregulate autophagy/mitophagy and how alterations of these pathways play beneficial or detrimental roles in dopamine neurons. The convergent and divergent effects of PD toxins on mitochondrial function and autophagy/mitophagy are also discussed in this review. Furthermore, we propose new diagnostic tools and discuss how pharmacological modulators of autophagy/mitophagy can be developed as disease-modifying treatments for PD. Finally, we discuss the critical need to identify endogenous and synthetic forms of PD toxins and develop efficient health preventive programs to mitigate the risk of developing PD.     

Apoptosis is Induced in Cancer Cells via the Mitochondrial Pathway by the Novel Xylocydine-Derived Compound JRS-15

The novel compound JRS-15 was obtained through the chemical modification of xylocydine. JRS-15 exhibited much stronger cytotoxic and pro-apoptotic activity than its parent compound in various cancer cell lines, with IC₅₀ values in HeLa, HepG2, SK-HEP-1, PC-3M and A549 cells ranging from 12.42 to 28.25 μM. In addition, it is more potent for killing cancer than non-cancerous cells. Mechanistic studies showed that JRS-15 treatment arrested cell cycle at the G1/S phase, which further triggered the translocation of Bax and Bak to the mitochondria, resulting in mitochondrial membrane potential (MMP) depolarization and the subsequent release of cytochrome c and the second mitochondria-derived activator of caspase (Smac). The sequential activation of caspase-9 and caspase-3/7 and the cleavage of poly (ADP-ribose) polymerase (PARP) were observed following these mitochondrial events. Caspase-8, an initiator caspase that is required to activate the membrane receptor-mediated extrinsic apoptosis pathway was not activated in JRS-15-treated cells. Further analysis showed that the levels of the anti-apoptotic proteins Bcl-xL and XIAP were significantly reduced upon JRS-15 treatment. Furthermore, the caspase-9 inhibitor z-LEHD-fmk, the pan-caspase inhibitor z-VAD-fmk, and Bcl-xL or XIAP overexpression all effectively prevented JRS-15-induced apoptosis. Taken together, these results indicate that JRS-15 induces cancer cell apoptosis by regulating multiple apoptosis-related proteins, and this compound may therefore be a good candidate reagent for anticancer therapy.     

Erythropoietin: New Directions for the Nervous System

New treatment strategies with erythropoietin (EPO) offer exciting opportunities to prevent the onset and progression of neurodegenerative disorders that currently lack effective therapy and can progress to devastating disability in patients. EPO and its receptor are present in multiple systems of the body and can impact disease progression in the nervous, vascular, and immune systems that ultimately affect disorders such as Alzheimer’s disease, Parkinson’s disease, retinal injury, stroke, and demyelinating disease. EPO relies upon wingless signaling with Wnt1 and an intimate relationship with the pathways of phosphoinositide 3-kinase (PI 3-K), protein kinase B (Akt), and mammalian target of rapamycin (mTOR). Modulation of these pathways by EPO can govern the apoptotic cascade to control β-catenin, glycogen synthase kinase-3β, mitochondrial permeability, cytochrome c release, and caspase activation. Yet, EPO and each of these downstream pathways require precise biological modulation to avert complications associated with the vascular system, tumorigenesis, and progression of nervous system disorders. Further understanding of the intimate and complex relationship of EPO and the signaling pathways of Wnt, PI 3-K, Akt, and mTOR are critical for the effective clinical translation of these cell pathways into robust treatments for neurodegenerative disorders.     

Whey-Derived Peptides at the Heart of the COVID-19 Pandemic

The renin–angiotensin system (RAS) is a key regulator of blood pressure and hypertension. Angiotensin-converting enzyme 2 (ACE2) and angiotensin-converting enzyme I (ACE) are two main components of the RAS that play a major role in blood pressure homeostasis. The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) uses ACE2 as a receptor to enter cells. Despite some controversies, numerous studies have reported a significant association between the use of ACE inhibitors and reduced risk of COVID-19. In our previous studies, we produced and identified peptide sequences present in whey hydrolysates exhibiting high ACE inhibitory activity. Therefore, the aim of this work is to obtain an improved understanding of the function of these natural peptides as RAS inhibitors and investigate their potential therapeutic role in the COVID-19 pandemic. The molecular interactions between peptides IPP, LIVTQ, IIAE, LVYPFP, and human ACE2 were assessed by employing a molecular docking approach. The results show that natural whey-derived peptides have a dual inhibitory action against both ACE and ACE2. This dual activity distinguishes these ACE inhibitory peptides from synthetic drugs, such as Captopril and Lisinopril which were not shown to inhibit ACE2 activity, and may represent a potential strategy in the treatment of COVID-19.