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Mathematical modeling and experimental studies on axial drilling load for rotary ultrasonic drilling of c/Sic composites

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INTERNATIONAL JOURNAL OF ADVANcED MANUFAcTURING TEcHNOLOGY 2020年第3-4期107卷 1309-1326页

作者： Islam, Shafiul Yuan, Songmei Li, Zhen Beihang Univ Beijing Engn Technol Res Ctr High Efficient & Gre Sch Mech Engn & Automat Beijing 100191 Peoples R China

ceramic matrix composites of type c/Sic have great potential in space applications because of their superior properties such as low density, high wear resistance, and high-temperature resistance. However, due to their heterogeneous, anisotropic, and unstable thermal properties, the machining is still challenging to achieve desired efficiency and quality. For advanced materials, rotary ultrasonic machining (RUM) is considered as a highly efficient technology. Predicting mechanical load in RUM can help to optimize input variables and reduce processing defects in composites. In this research, a mathematical axial drilling load (force and torque) model has been developed based on the indentation fracture theory of material removal mechanism considering penetration trajectory and energy conservation theorem for rotary ultrasonic drilling (RUD) of c/Sic. Experiments were conducted on c/Sic composites to validate the model, and experimental results agreed well with model predictions with less than 14% (force) and 10% (torque) error. Therefore, this theoretical model can be effectively applied to predict axial drilling load during RUD of c/Sic. The relationships of axial drilling force and torque with machining process parameters, including spindle speed, feed rate, and ultrasonic power, were investigated. A specific range of experiments was carried out to demonstrate the benefit of ultrasonic vibration in RUD over conventional drilling (cD) on mechanical load for a designed drilling tool. It was noticed that RUD outperformed cD with a maximum of 38.11% and 34.30% in axial drilling force and torque reduction, respectively. The influence of drilling tool flute length on drilling performance was also elucidated based on a set of experiments using several designed drilling tools.

关键词： Rotary ultrasonic drilling c Sic composites Mechanical load (force and torque) Mathematical modeling Drilling tool flutes

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Efficient Electrocatalytic Performance of WP Nanorods Propagated on WS2/c for Hydrogen Evolution Reduction

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cHEMELEcTROcHEM 2020年第14期7卷 3082-3088页

作者： Yang, Jinzhou Yu, Zong-Bao Sun, Wei Li, Yue Wu, Hongda Geng, Zhongxing Yang, Zhanxu Liaoning Shihua Univ Sch Petrochem Engn Fushun 113001 Liaoning Peoples R China

Through a stepwise synthesis, intercalation followed by chemical vapor deposition (cVD) method, WP nanorods have been grown on the surface of WS2/c composite. compared to WS2/c, WP nanorods@WS2/c demonstrate better hydrogen evolution reaction (HER) activity and long-term chronopotentiometric stability as well as suitability in both acid electrolyte and alkaline electrolyte. In order to uncover the enhanced HER property reason, systematic characterizations were applied to assist analyzing. The characterizations used include X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS), electrochemical impedance spectroscopy (EIS), electrochemical active surface area (EcSA), Raman, and BET. Based on the analysis, it points that improved EcSA, synergy between WS(2)and WP nanorods, and enhanced degree of graphitization as well, leads to better HER activities of WP nanorods@WS2/c over WS2/c. This work highlights significant role of WP nanorods in WP/WS2/c three-phase composite in electrocatalytic hydrogen evolution and may evoke new interest in related nanostructure study.

关键词： WP nanorods@WS2 c hydrogen evolution reduction chemical vapor deposition

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Exploring How (Ti plus Mo)/c and Ti/Mo Influence the Precipitation Behaviors within Microalloyed Steels: Experimental Evidence and Related Patents Investigation

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JOURNAL OF MATERIALS ENGINEERING AND PERFORMANcE 2020年第3期29卷 1882-1891页

作者： chen, chih-Yuan chiang, Lung-Jen chen, chien-chon Liao, Meng-Hsuan Kuo, Jih-Sheng chou, Ya-Hsuan Natl Taipei Univ Technol Grad Inst Intellectual Property Taipei 10608 Taiwan China Steel Corp Iron & Steel Res & Dev Dept Kaohsiung 81233 Taiwan Natl United Univ Dept Energy Engn Miaoli 36063 Taiwan

The main objective of the present study was to understand the influences of different atomic ratios of Ti/Mo and (Ti + Mo)/c on the precipitation behaviors in Ti-Mo HSLA steels. It was found that the steel with a higher Ti/Mo atomic ratio possessed a large theoretical volume fraction of precipitated carbides, but the ferrite matrix did not achieve a corresponding higher microhardness. On the other hand, the experimental results also indicated that it was not suitable to assess the precipitation strengthening effect of the ferrite matrix based on only one of the atomic factors, i.e., (Ti + Mo)/c or Ti/Mo. In addition, from the present study, similarity of the (Ti + Mo)/c atomic ratios is a prerequisite for comparing the precipitation hardening effects in steels having different Ti/Mo atomic ratios. Besides experimental data, the main deduction is also supported by related patent information, which further corroborates the reliability of the present study. Furthermore, of the two steels with different M/c atomic ratios, the ferrite matrix of the H-(M/c) steel showed a rising trend in Vickers hardness when the isothermal holding time was increased from 5 min to 60 min at 650-700 degrees c. This higher strengthening ability, which occurs within ferrite grains after holding at longer times, can be ascribed to the higher austenite decomposition rate occurring in the H-(M/c) atomic ratio steel. Therefore, the hardening mechanisms in both kinds of steel are also discussed in the present study.

关键词： interphase precipitation precipitation random precipitation Ti Mo (Ti plus Mo) c

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Synthetic ablations in the c. elegans nervous system

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NETWORK NEUROScIENcE 2020年第1期4卷 200-216页

作者： Towlson, Emma K. Barabasi, Albert-Laszlo Univ Network Sci Inst Dept Phys NE Boston MA USA MIT Media Lab Cambridge MA USA Univ Network Sci Inst Dept Phys NE Boston MA USA Brigham & Women's Hosp Harvard Med Sch Dept Med Boston MA USA Univ Dept Network & Data Sci Cent European Budapest Hungary

Author Summary "Synthetic lethality" in cell biology is an extreme example of the effects of higher order genetic interactions: The simultaneous knockout of two or more individually nonessential genes leads to cell death. We define a neural analog to this concept in relation to the locomotor response to gentle touch in c. elegans. Two or more neurons are synthetic essential if individually they are not required for this behavior, yet their combination is. We employ a network control approach to systematically assess all pairs and triplets of neurons by their effect on body wall muscle controllability, and find that only surprisingly small sets of neurons are synthetic essential. They are highly localized in the nervous system and predicted to affect control over specific sets of muscles. Synthetic lethality, the finding that the simultaneous knockout of two or more individually nonessential genes leads to cell or organism death, has offered a systematic framework to explore cellular function, and also offered therapeutic applications. Yet the concept lacks its parallel in neuroscience-a systematic knowledge base on the role of double or higher order ablations in the functioning of a neural system. Here, we use the framework of network control to systematically predict the effects of ablating neuron pairs and triplets on the gentle touch response. We find that surprisingly small sets of 58 pairs and 46 triplets can reduce muscle controllability in this context, and that these sets are localized in the nervous system in distinct groups. Further, they lead to highly specific experimentally testable predictions about mechanisms of loss of control, and which muscle cells are expected to experience this loss.

关键词： c elegans Graph theory Network control theory Neuronal ablations Synthetic lethality

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Does influent c/N ratio affect pollutant removal and greenhouse gas emission in wastewater ecological soil infiltration systems with/without intermittent aeration?

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WATER ScIENcE AND TEcHNOLOGY 2020年第4期81卷 668-678页

作者： Pang, Junling Yang, Mo Tong, Deli Fu, Xu Huang, Linli Sun, Bo Pan, Jing Shenyang Normal Univ Coll Life Sci Shenyang 110034 Peoples R China

Wastewater ecological soil infiltration system (WESIS) is a land treatment technology for decentralized wastewater treatment that has been applied all over the world. In this study, the pollutant removal, emission of greenhouse gases (GHGs) and functional gene abundances with different influent c/N ratios were evaluated in WESISs with/without intermittent aeration. Intermittent aeration and influent c/N ratio affect pollutant removal and GHG emission. Increased influent c/N ratio led to high total nitrogen (TN) removal, low cH4 and N2O emission in the aerated WESIS, which was different from the non-aerated WESIS. High average removal efficiencies of chemical oxygen demand (cOD) (94.8%), NH4+-N (95.1%), TN (91.2%), total phosphorus (TP) (91.1%) and low emission rates for cH4 (27.2 mg/(m(2) d)) and N2O (10.5 mg/(m(2) d)) were achieved with an influent c/N ratio of 12:1 in the aerated WESIS. Intermittent aeration enhanced the abundances of bacterial 16S rRNA, amoA, nxrA, narG, napA, nirK, nirS, qnorB, nosZ genes and decreased the abundances of the mcrA gene, which are involved in pollutant removal and GHG emission. Intermittent aeration would be an effective alternative to achieving high pollutant removal and low cH4 and N2O emission in high influent c/N ratio wastewater treatment.

关键词： aeration c N ratio greenhouse gas wastewater ecological soil infiltration system

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changes in climate suitability for oil-tea (c. oleifera Abel) production in china under historical and future climate conditions

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AGRIcULTURAL AND FOREST METEOROLOGY 2022年 316卷 108843-108843页

作者： Wu, Dingrong Wang, Peijuan Huo, Zhigguo Yuan, Xiaokang Jiang, Huifei Yang, Jianying Tang, Junxian Ma, Yuping Chinese Acad Meteorol Sci State Key Lab Severe Weather LASW Beijing 100081 Peoples R China Nanjing Univ Informat Sci & Technol Collaborat Innovat Ctr Meteorol Disaster Forecast Nanjing 210044 Peoples R China Hunan Res Inst Meteorol Sci Changsha 410118 Peoples R China China Agr Univ Coll Resource & Environm Sci Beijing 100193 Peoples R China

Defining climate suitability zones accurately can provide supporting information for locating regions for crops with a long period of return on investment such as oil-tea (c. oleifera). The objective of this study was to evaluate changes in suitability for a typical oil-tea species (Abel) under climate change conditions in china. Based on correlation analysis, annual mean temperature, mean temperature in July, annual rainfall, and annual sunshine hours were identified as the factors impacting production suitability. A modified bioclimatic method was verified using extensively collected crop occurrence data. changes in climate suitability under two different historical periods (1961-1990, 1991-2020) and under two future climate change periods (2021-2050, 2051-2100) using 28 General circulation Models (GcMs) under Representative concentration Pathway (RcP) 4.5 and 8.5 emission scenarios were then investigated. Results showed that: (1) The modified method well described the main climatic features of the actual production regions;96.3% of the dominant production regions and 92.4% of the main production regions were located in the regions classified as most suitable and suitable;(2) Historical climate change has caused the northern and southern production boundaries to move northward by 130 and 70 km, respectively, and the east-central part of the study region has degraded to the suitable classification;(3) Under RcP 4.5, the regional pattern of suitability did not change much, while under RcP 8.5, the area of the most suitable region was reduced by up to 66%;(4) Suitability varied greatly between different GcMs, especially under RcP 8.5. Our results showed that historical climate change had negative impacts in some of the most suitable regions, and that future climate change will have negative impacts on more regions. To maintain future healthy development of production, significant efforts should be devoted to breeding heat and drought-resistant varieties and to improv

关键词： climate change climate suitability Global climate models c oleifera Abel

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Serum cystatin c levels are negatively correlated with post-stroke cognitive dysfunction

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Neural Regeneration Research 2020年第5期15卷 922-928页

作者： Dao-Xia Guo Zheng-Bao Zhu chong-Ke Zhong Xiao-Qing Bu Li-Hua chen Tan Xu Li-Bing Guo Jin-Tao Zhang Dong Li Jian-Hui Zhang Zhong Ju chung-Shiuan chen Jing chen Yong-Hong Zhang Jiang He Department of Epidemiology School of Public Health and Jiangsu Key Laboratory of Preventive and Translational Medicine for Geriatric DiseasesMedical College of Soochow UniversitySuzhouJiangsu ProvinceChina Department of Epidemiology Tulane University School of Public Health and Tropical MedicineNew OrleansLAUSA Department of Neurology Siping Central HospitalSipingJilin ProvinceChina Department of Neurology the 88th Hospital of People’s Liberation ArmyTaianShandong ProvinceChina Department of Internal Medicine Feicheng City People’s HospitalFeichengShandong ProvinceChina Department of Neurology Tongliao Municipal HospitalInner Mongolia Autonomous RegionChina Department of Neurology Kerqin District First People’s Hospital of Tongliao CityInner Mongolia Autonomous RegionChina Department of Medicine Tulane University School of MedicineNew OrleansLAUSA

Stroke is the leading cause of death and long-term disability worldwide,and cognitive impairment and dementia are major complications of ischemic *** c (cysc) has been found to be a neuroprotective factor in animal ***,the relationship between cysc levels and cognitive dysfunction in previous studies has revealed different *** prospective observational study investigated the correlation between serum cysc levels and post-stroke cognitive dysfunction at 3 *** from 638 patients were obtained from the china Antihypertensive Trial in Acute Ischemic Stroke (cATIS).cognitive dysfunction was assessed using the Mini-Mental State Examination (MMSE) at 3 months after *** to the MMSE score,308 patients (52.9%) had post-stroke cognitive *** adjusting for potential confounding factors,the odds ratio (95% cI) of post-stroke cognitive dysfunction for the highest quartile of serum cysc levels was 0.54 (0.30–0.98),compared with the lowest *** correlation between serum cysc and cognitive dysfunction was modified by renal function *** observed a negative linear dose-response correlation between cysc and cognitive dysfunction in patients with normal renal function (Plinearity = 0.044),but not in those with abnormal renal *** serum cysc levels were correlated with a low risk of 3-month cognitive dysfunction in patients with acute ischemic stroke,especially in those with normal renal *** current results suggest that cysc is a protective factor for post-stroke cognitive dysfunction,and could be used to treat post-stroke cognitive *** cATIS study was approved by the Institutional Review Boards at Soochow University from china (approval No.2012-02) on December 30,2012,and was registered at *** (identifier ***01840072) on April 25,2013.

关键词： abnormal renal function cognitive dysfunction cystatin c ischemic stroke Mini-Mental State Examination neural regeneration neuroprotective effect normal renal function

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Short stature explained by dimerization of human growth hormone induced by a p.c53S point mutation

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JOURNAL OF BIOLOGIcAL cHEMISTRY 2020年第15期295卷 4893-4901页

作者： Sander, Max Wu Zida Strasburger, christian J. Univ Med Berlin Dept Endocrinol Diabet & Nutr Med Campus Charite MitteCharitepl 1 D-10117 Berlin Germany

A homozygous mutation in growth hormone 1 (GH1) was recently identified in an individual with growth failure. This mutation, c.705G>c, causes replacement of cysteine at position 53 of the 191-amino-acid sequence of 22 kDa human GH (hGH) with serine (p.c53S). This hGH molecule (hereafter referred to as GH-c53S) lacks the disulfide bond between ***-53 and ***-165, which is highly conserved among species. It has been reported previously that monomeric GH-c53S has reduced bioactivity compared with WT GH (GH-WT) because of its decreased ability to bind and activate the GH receptor in vitro. In this study, we discovered that substitution of ***-53 in hGH significantly increased formation of hGH dimers in pituitary cells. We expressed His-tagged hGH variants in the cytoplasm of genetically modified Rosetta-gami B DE3 Escherichia coli cells, facilitating high-yield production. We observed that the bioactivity of monomeric GH-c53S is 25.2% of that of GH-WT and that dimeric GH-c53S?His has no significant bioactivity in cell proliferation assays. We also found that the expression of GH-c53S in pituitary cells deviates from that of GH-WT. GH-c53S was exclusively stained in the Golgi apparatus, and no secretory granules formed for this variant, impairing its stimulated release. In summary, the unpaired cys-165 in GH-c53S forms a disulfide bond linking two hGH molecules in pituitary cells. We conclude that the GH-c53S dimer is inactive and responsible for the growth failure in the affected individual.

关键词： growth hormone disulfide dimerization pituitary gland protein folding c 705G>c cysteine GH-c53S growth hormone deficiency

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Simultaneous nitrogen and carbon removal in a packed A/O reactor: effect of c/N ratio on microbial community structure

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BIOPROcESS AND BIOSYSTEMS ENGINEERING 2020年第7期43卷 1241-1252页

作者： Ding, Shuai He, Jian Luo, Xingzhang Zheng, Zheng Fudan Univ Dept Environm Sci & Engn Room 2026Environm Bldg2005 Songhu Rd Shanghai 200433 Peoples R China

In this research, a novel packed anoxic/oxic moving bed biofilm reactor (MBBR) was established to achieve high-organic matter removal rates, despite the carbon/nitrogen (c/N) ratio of 2.7-5.1 in the influent. Simultaneous nitrification-denitrification (SND) was investigated under a long sludge retention time of 104 days. The system exhibited excellent performance in pollutant removal, with chemical oxygen demand and total nitrogen (TN) enhanced to 93.6-97.4% and 34.4-60%, respectively. Under low c/N conditions, the nitrogen removal process of A/O MBBR system was mainly achieved by anaerobic denitrification. The increase of c/N ratio enhanced SND rate of the aerobic section, where dissolved oxygen was maintained at the range of 4-6 mg/L, and resulted in higher TN removal efficiency. The microbial composition and structures were analyzed utilizing the MiSeq Illumina sequencing technique. High-throughput pyrosequencing results indicated that the dominant microorganisms were Proteobacteria and Bacteroidetes at the phylum level, which contributes to the removal of organics matters. In the aerobic section, abundances of Nitrospirae (1.12-29.33%), Burkholderiales (2.15-21.38%), and Sphingobacteriales (2.92-11.67%) rose with increasing c/N ratio in the influent, this proved that SND did occur in the aerobic zone. As the c/N ratio of influent increased, the SND phenomenon in the aerobic zone of the system is the main mechanism for greatly improving the removal rate of TN in the aerobic section. The c/N ratio in the aerobic zone is not required to be high to exhibit good TN removal performance. When c/NH4+ and c/TN in the aerobic zone were higher than 2.29 and 1.77, respectively, TN removal efficiency was higher than 60%, which means that carbon sources added to the reactor could be saved. This study would be vital for a better understanding of microbial structures within a packed A/O MBBR and the development of cost-efficient strategies for the treatment of low c/N wastewate

关键词： Packed A O reactor Moving bed biofilm reactor c N ratio Simultaneous nitrification-denitrification (SND) Microbial community structure

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Preparation of high performance LiFePO4/c by extracting iron element from iron tailings by concentrated sulfuric acid hot dip method

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IONIcS 2020年第4期26卷 1645-1655页

作者： Wang, Yingling Wang, Yafeng Luo, Shaohua Liu, chengjun Teng, Fei chen, Huanhuan Shen, Huiliang Gao, Desheng Northeastern Univ Sch Met Shenyang 110819 Peoples R China Northeastern Univ Minist Educ Key Lab Ecol Met Multimetall Ores Shenyang 110819 Peoples R China Northeastern Univ Qinhuangdao Sch Resources & Mat Qinhuangdao 066004 Hebei Peoples R China Northeastern Univ Sch Mat Sci & Engn Shenyang 110819 Peoples R China

LiFePO4/c cathode materials are synthesized by carbothermal reduction process using FePO4 as iron and phosphorus source, and starch as carbon source. The FePO4 precursor was prepared by leaching iron tailings with concentrated sulfuric acid and then leaching with phosphoric acid and hydrogen peroxide. The morphology and structure of FePO4 precursors prepared under different pH conditions were studied by using thermogravimetric-differential analysis (TG-DTA), infrared analysis (FTIR), x-ray diffraction (XRD), and field emission scanning electron microscopy (FESEM). The effect of the FePO4 material on the properties of the synthesized LiFePO4 cathode was investigated by charge and discharge cycles. On this basis, the effects of different molar ratios of c and LiFePO4 on the performance of synthetic product LiFePO4/c were studied using starch as carbon source. The results show that the FePO4 precursor prepared under the condition of pH 2 is the raw material, and the LiFePO4/c cathode material synthesized by adding 45% carbon has the best performance. The first cycle discharge capacity reached 142.6 mAh g(-1) at a current density of 0.1 degrees c, reaching 83.9% of its theoretical capacity. This work proposes a novel and effective method to utilize the iron tailings.

关键词： cathode material LiFePO4 c Iron tailings concentrated sulfuric acid leaching FePO4 precursor

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