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AcHIEvING THRESHOLD BARRIER OF 1 nm ROUGHNESS vALUE OF SILIcON SURFAcE BY DIAMOND TURNING

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chinese Journal of Mechanical Engineering 1998年第1期11卷 7-11,19页

作者： Fang, Fengzhou venkatesh, v.c. Nanyang Technological Univ Singapore Singapore

nm roughness value of silicon surface by diamond turning is obtained firstly and three novel techniques are proposed. The surface integrity is studied in detail by using atomic force microscope, scanning electron microscope, and stylus surface instrument. The diamond tool sharpness has a considerable influence on the machined surface, therefore a novel technique—brightness modulation for measuring accurately the edge of the cutter is proposed. Mirror surfaces are assessed by another novel technique—a measure of their reflectivity. A third technique, single grit diamond machining is carried out. It supplies a experimental evidence for verifying the obtained high quality turned surfaces.

关键词： Mirror surfaces Diamond turning Brittle materials Single grit machining

MicroRNAs as potential diagnostic biomarkers for bipolar disorder

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Neural Regeneration Research 2025年第6期20卷 1681-1695页

作者： Bridget Martinez Philip v.Peplow Department of Pharmacology University of Nevada-RenoRenoNVUSA Department of Medicine University of Nevada-RenoRenoNVUSA Department of Anatomy University of OtagoDunedinNew Zealand

Abnormal expression of microRNAs is connected to brain development and disease and could provide novel biomarkers for the diagnosis and prognosis of bipolar disorder. We performed a PubMed search for microRNA biomarkers in bipolar disorder and found 18 original research articles on studies performed with human patients and published from January 2011 to June 2023. These studies included microRNA profiling in bloodand brain-based materials. From the studies that had validated the preliminary findings,potential candidate biomarkers for bipolar disorder in adults could be miR-140-3p,-30d-5p,-330-5p,-378a-5p,-21-3p,-330-3p,-345-5p in whole blood, miR-19b-3p,-1180-3p,-125a-5p, let-7e-5p in blood plasma, and miR-7-5p,-23b-5p,-142-3p,-221-5p,-370-3p in the blood serum. Two of the studies had investigated the changes in microRNA expression of patients with bipolar disorder receiving treatment. One showed a significant increase in plasma miR-134 compared to baseline after 4 weeks of treatment which included typical antipsychotics, atypical antipsychotics, and benzodiazepines. The other study had assessed the effects of prescribed medications which included neurotransmitter receptorsite binders(drug class B) and sedatives, hypnotics, anticonvulsants, and analgesics(drug class c) on microRNA results. The combined effects of the two drug classes increased the significance of the results for miR-219 and-29c with miR-30e-3p and-526b* acquiring significance. MicroRNAs were tested to see if they could serve as biomarkers of bipolar disorder at different clinical states of mania, depression, and euthymia. One study showed that upregulation in whole blood of miR-9-5p,-29a-3p,-106a-5p,-106b-5p,-107,-125a-3p,-125b-5p and of miR-107,-125a-3p occurred in manic and euthymic patients compared to controls, respectively, and that upregulation of miR-106a-5p,-107 was found for manic compared to euthymic patients. In two other studies using blood plasma,downregulation of miR-134 was observed i

关键词： biomarker bipolar disorder blood leukocytes blood plasma blood plasma extracellular vesicles/exosomes blood serum brain tissue brain tissue extracellular vesicles/exosomes lymphoblastoid cell lines microRNA neural progenitor cells whole blood

MicroRNAs as potential biomarkers for diagnosis of post-traumatic stress disorder

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Neural Regeneration Research 2025年第7期20卷 1957-1970页

Post-traumatic stress disorder is a mental disorder caused by exposure to severe traumatic life ***,there are no validated biomarkers or laboratory tests that can distinguish between trauma survivors with and without post-traumatic stress *** addition,the heterogeneity of clinical presentations of post-traumatic stress disorder and the overlap of symptoms with other conditions can lead to misdiagnosis and inappropriate *** suggests that this condition is a multisystem disorder that affects many biological systems,raising the possibility that peripheral markers of disease may be used to diagnose post-traumatic stress *** performed a PubMed search for microRNAs(miRNAs)in post-traumatic stress disorder(PTSD)that could serve as diagnostic biomarkers and found 18 original research articles on studies performed with human patients and published January 2012 to December *** included four studies with whole blood,seven with peripheral blood mononuclear cells,four with plasma extracellular vesicles/exosomes,and one with serum *** of these studies had also used whole *** studies were excluded as they did not involve microRNA *** of the studies had collected samples from adult male veterans who had returned from deployment and been exposed to combat,and only two were from recently traumatized adult *** measuring miRNA expression levels,many of the studies had used microarray miRNA analysis,miRNA Seq analysis,or NanoString *** six studies had used real time polymerase chain reaction assay to determine/validate miRNA expression in PTSD subjects compared to *** miRNAs that were found/validated in these studies may be considered as potential candidate biomarkers for PTSD and include miR-3130-5p in whole blood;miR-193a-5p,-7113-5p,-125a,-181c,and-671-5p in peripheral blood mononuclear cells;miR-10b-5p,-203a-3p,-4488,-502-3p,-874-3p,-5100,and-7641 in plasma extracellular vesicles/

关键词： biomarker diagnosis microRNA peripheral blood mononuclear cells plasma extracellular vesicles/exosomes post-traumatic stress disorder serum exosomes whole blood whole plasma

Tribological behaviour of c/c-Sic composites-A review

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Journal of Advanced ceramics 2016年第1期5卷 1-12页

作者： Parshant KUMAR v.K.srivastava Department of Mechanical Engineering Indian Institute of Technology(BHU) Varanasi-221005 India

ceramic matrix composites made of carbon fibres and carbon matrix (c/c) are generally used for aircraft structures and brake discs due to their low density, and good thermal, mechanical, and tribological properties. Silicon carbide (Sic) can be introduced to the matrix to improve the performance of c/c composites, because it increases the hardness and thermal stability, and decreases the chemical reactivity, which leads to the improvement of tribological properties of c/c composites. Thus carbon–carbon silicon carbide (c/c–Sic) composites can be used at high temperature for the application of brake discs, friction clutches, etc. c/c–Sic composites are fabricated by three different methods: (i) chemical vapour infiltration (cvI), (ii) polymer infiltration and pyrolysis (PIP), and (iii) liquid silicon infiltration (LSI), among which LSI method is widely used for the fabrication of c/c–Sic composites due to higher mechanical and thermal properties.

关键词： carbon-carbon (c/c) composites coefficient of friction wear

valveless pumping using a two-stage impedance pump

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Frontiers of Mechanical Engineering 2013年第3期8卷 311-318页

作者： v.c.-c.LEE Y.A.ABAKR K.-c.WOO School of Engineering and Science Curtin University Sarawak MalaysiaCDT 25098009 MiriSarawakMalaysia Department of Mechanical Materials and ManufacturingUniversity of Nottingham Malaysia CampusJalan Broga43500 SemenyihSelangor Darul EhsanMalaysia

Impedance pump is defned as a type of valveless pumping mechanism,where an elastic tube is joined with a tube of different impedance,a periodic asymmetrical compression on part of the elastic tube will produce a unidirectional *** and experimental studies had been conducted in the past,but little experimental work was found to exploit the principle of multi-stage impedance pumping for fuid *** paper concentrates on the fuid behavior for an openloop two-stage system *** aim of this work is to have an insight on the deliverable head and pumping rate of an open-loop two-stage impedance pumping *** paper generally investigates the effect of different parameters towards the generation of unidirectional fows and composite fow of two opposite *** obtained are of signifcant values.

关键词： valveless pumping open-loop two-stage unidirectional composite

Application of IITM-RANS3D to free-fall water entry of prismatic and non-prismatic finite wedges

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Journal of Hydrodynamics 2023年第3期35卷 417-430页

作者： Shaswat Saincher Kshitij srivastava R.vijayakumar v.Sriram center for Maritime Experiments to Maritime Experience(ME2ME) Indian Institute of Technology MadrasChennaiIndia Department of Ocean Engineering Indian Institute of Technology MadrasChennaiIndia

High-speed watercraft and ships undergo coupled motions which make the front portion of the hull exit and violently re-enter *** induces short-term slamming loads that may compromise the structural integrity of the *** slamming of the bow can be modeled as straight wedges of different deadrise angles(DRAs)falling into water from different *** advent of computational fluid dynamics has allowed the problem of wedge-slamming to be simulated using the full Navier-Stokes equations thus complementing the pioneering studies based on ***,most researchers are opting to use commercial software to simulate the wedge-impact problem as it allows access to overset meshing algorithms which are robust in modeling the wedge as a moving *** boundary methods(EBMs)offer some advantages over overset meshing in that the mesh only needs to be generated once and cartesian mesh-based solvers can be ***,the application of EBMs to wedge-impact has been limited in the literature and merits further *** this context,we investigate the applicability of the fast-fictitious-domain(FFD)based embedded boundary treatment to simulate the violent water-entry of *** extend our in-house Navier-Stokes model IITM-RANS3D to handle floating bodies through integration of a rigid-body dynamics solver and an algorithm to embed three-dimensional stereolithography(STL)geometries as solids over a cartesian *** proposed algorithm is extensively benchmarked against variable DRA wedge-slamming experiments reported in the literature as well as constant DRA wedge-slamming experiments performed *** good agreement is reported in terms of the time-history of hydrodynamic impact pressures measured at various locations on the hull as well as the wedge motion responses thus demonstrating the suitability of FFD for simulating the coupled hydrodynamics of slamming for simplified hull geometries.

关键词： Wedge water entry slamming fast-fictitious-domain IITM-RANS3D experiments

compositionally Graded Microstructure for Ag-Fe Nanoparticles

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Nano-Micro Letters 2012年第3期4卷 172-175页

作者： chandan srivastava K.v.L.Sushma Department of Materials Engineering Indian Institute of Science

Ag-Fe nanoparticles with a highly Ag rich average composition were synthesized by the sonochemical ***-iron system exhibits a wide miscibility gap in the bulk ***,a graded compositional profile along the nanoparticle radius was *** at and near the surface of the nanoparticle contained both Ag and Fe *** composition got relatively deficient Fe towards the center of the particle with particle core made up of pure *** of Ag and Fe is confirmed by the absence of diffraction signal corresponding to pure Fe phase and presence of a paramagnetic phase in nanoparticles containing a diamagnetic(Ag)and ferromagnetic(Fe)elements.

关键词： Nanoparticles Electron Microscopy Ag-Fe Miscibility gap Solid solution Microstructure

Irritable bowel syndrome and small intestinal bacterial overgrowth:Meaningful association or unnecessary hype

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World Journal of Gastroenterology 2014年第10期20卷 2482-2491页

作者： Uday c Ghoshal Deepakshi srivastava Department of Gastroenterology Sanjay Gandhi Post Graduate Institute of Medical Sciences Lucknow 226104 India

Irritable bowel syndrome (IBS) is a common condition characterized by abdominal pain or discomfort, bloating, and altered stool form and passage. Small intestinal bacterial overgrowth (SIBO) is a condition in which there is overgrowth of bacteria in small bowel in excess of 105 colony forming units per milliliter on culture of the upper gut aspirate. Frequency of SIBO varied from 4%-78% among patients with IBS and from 1%-40% among controls. Higher frequency in some studies might be due to fallacious criteria [post-lactulose breath-hydrogen rise 20 PPM above basal within 90 min (early-peak)]. Glucose hydrogen breath test (GHBT) has a low sensitivity to diagnose SIBO. Hence, studies based on GHBT might have under-estimated frequency of SIBO. Therefore, it is important to analyze these studies carefully to evaluate whether the reported association between IBS and SIBO is over or under-projected. This review evaluates studies on association between SIBO and IBS, discordance between different studies, their strength and weakness including methodological issues and evidence on therapeutic manipulation of gut flora on symptoms of IBS.

关键词： Glucose hydrogen breath test Lactulose hydrogen breath test Functional bowel disease Dysbiosis Gut flora

Effect of hydrogen plasma treatment on the growth and microstructures of multiwalled carbon nanotubes

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Nano-Micro Letters 2010年第1期2卷 42-48页

作者： S.K.srivastava v.D.vankar v.Kumar Department of Physics Indian Institute of Technology Delhi National Physical Laboratory Dr.K.S.Krishnan Marg

The effect of hydrogen plasma treatment of iron oxide films on the growth and microstructure of carbon nanotubes(cNTs)by microwave plasma enhanced chemical vapor deposition process has been *** plasma was characterized in-situ using optical emission *** of the films was examined by scanning electron *** analysis was carried out by high resolution transmission electron microscopy(HRTEM)equipped with energy dispersive X-ray spectroscopy(EDS)and micro-diffraction *** is found that oxide films without H_2 plasma pretreatment or treated for lesser time resulted in cNT films with high percentage of carbonaceous particles and with embedded particles/nanorods distributed discontinuously in the cavity of the *** embedded particles were found to be of iron carbide(Fe-c)as confirmed by HRTEM,EDS and micro-diffraction *** observations suggested that the iron oxide particles had poor catalytic action for cNT growth and in-situ reduction of oxide clusters to Fe by hydrogen plasma plays a key role in discontinuous filling of the nanotubes by the catalytic particles.

关键词： carbon nanotubes chemical vapor deposition Iron carbide MPEcvD