103 research outputs found

    Expression levels of apoptotic factors in a rat model of corticosteroid-induced femoral head necrosis

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    Purpose: To study the expression levels of apoptotic factors in corticosteroid-mediated femoral head necrosis (FHN) in rats. Methods: Sprague-Dawley (SD) rats (n = 60) bred adaptively for one week were randomly assigned to control and model groups (30 rats/group). A rat model of corticosteroid-induced femoral head necrosis was established. Then, 3 mL of blood drawn from the inferior vena cava of each rat was used for the assay of the expression levels of osteoprotegerin (OPG) and osteoclast differentiation factor (RANKL) in each group using enzyme-linked immunosorbent assay (ELISA). The caspase-3- and Bcl-2-+ve cells in each group were determined with immunohistochemical method. Results: Relative to control, serum OPG level of model group was significantly decreased, while the RANKL level was markedly raised (p < 0.05). The degree of empty lacunae in the model rats was markedly increased, relative to control. Caspase-3-+ve cells were more numerous in the model group than in control, while Bcl-2-positive cells were markedly decreased compared to control (p < 0.05). Conclusion: Apoptosis occurs in the rat model of femoral head necrosis. Glucocorticoids may regulate the apoptotic process by  upregulating caspase-3 and inhibiting Bcl-2. This provides a novel lead for FHN therapy. Keywords: Femoral head necrosis, Corticosteroid, Glucocorticoid, Apoptosi

    Application of a Force Sensor in Wire Bonding Process

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    Wire bonder is important equipment in semiconductor end-package. The benefits of using force sensor are precisely force control and earlier contact detection. In this paper, we introduced an application of a force sensor in the wire bonding process. We proposed the control strategy of the whole bonding process with the force sensor. In the bonding process, it's very important to make sure the safety before switching between the force control and position control. A contact detection method in force mode was introduced to get a smooth switch from position control to force control. Before switching from the force control to position control, a two-steps method was proposed to prevent vibrations. The experiments results show that a good bonding performance was achieved by applying with the force sensor

    Application of a Force Sensor in Wire Bonding Process

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    Abstract: Wire bonder is important equipment in semiconductor end-package. The benefits of using force sensor are precisely force control and earlier contact detection. In this paper, we introduced an application of a force sensor in the wire bonding process. We proposed the control strategy of the whole bonding process with the force sensor. In the bonding process, it's very important to make sure the safety before switching between the force control and position control. A contact detection method in force mode was introduced to get a smooth switch from position control to force control. Before switching from the force control to position control, a twosteps method was proposed to prevent vibrations. The experiments results show that a good bonding performance was achieved by applying with the force sensor

    A Synthetic Material to Simulate Soft Rocks and Its Applications for Model Studies of Socketed Piles

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    A detailed manufacturing procedure of a synthetic soft rock is presented, as well as its applications on the laboratory experiments of socketed piles. With the homogeneity and isotropy of the simulated soft rock, the influence of different variables on the bearing performance could be investigated independently. The constituents, cement, gypsum powder, river sand, concrete-hardening accelerator, and water, were mixed to form the specimens. Both uniaxial and triaxial compressive tests were conducted to investigate the stress-strain behavior of the simulated soft rock. Additionally, the simulated soft rock specimens were used in model pile tests and simple shear tests of the pile-rock interface. Results of the simulated soft rock in both the uniaxial and triaxial compressive tests are consistent with those of natural soft rocks. The concrete-hardening accelerator added to the mixtures improves the efficiency in laboratory investigations of soft rock specimens with a curing time of 7 days. The similarities between the laboratory tests and the field observations provide convincing evidence to support its suitability in modeling the behavior of soft rocks

    Scale response of summer urban heat island to building plot ratio and its warning parameter

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    Omjer građevne čestice je značajan pokazatelj arhitektonskog rasporeda koji utječe na urbani toplinski otok (UHI - urban heat island). Prethodna su istraživanja usredotočena na omjer visina/težina, gustoću zgrada i ostale pokazatelje povezane s omjerom građevne čestice, ali ne uspijevaju uspješno opisati odnos vrijeme-prostor između omjera građevne čestice i UHI te točno voditi planiranje i projekt kako bi se smanjila učinkovitost UHI-a. Metoda stupnja osjetljivosti predložena je za analiziranje reakcije vrijeme-prostor UHI-a na omjer građevne čestice u svrhu reguliranja intenziteta UHI (UHII) do kojeg je došlo prihvatljivim omjerom građevne čestice tijekom planiranja i projektiranja. Osjetljivost omjera građevnih čestica u različitim prostornim omjerima prema UHI tijekom dana izračunata je redom pomoću 3S tehnologije, MATLABa, SPSS-a i drugih platformi zasnovanih na teoriji razmjere ekologije pejzaža i metodi geo-statističke analize. Razmatrana je krivulja promjene reakcije omjera građevne čestice na UHI u najosjetljivijoj prostornoj ljestvici. Tada je izrađen standard prevencije i kontrole UHI-a ljeti prema temperaturi tijekom najtoplijih ljetnih dana i ljudskoj fiziološkoj reakciji kod visokih temperatura, i odgovarajućim nacionalnim pravilima. Dano je upozorenje na parametre omjera građevne čestice na temelju porasta temperature UHI-a zbog omjera građevne čestice. Rezultati pokazuju da postoji skala osjetljivosti između omjera građevne čestice i UHI. Po danu se odnos između osnovnog omjera građevne čestice i ljetnog UHI-a pomiče od negativne ka pozitivnoj korelaciji. Učinak porasta temperature poslije podne veći je od jutarnjeg rashlađenja. Osnovni omjer građevne čestice je u linearnom odnosu s ljetnim UHII. Povećanje prosječnog omjera čestice dovodi do smanjenja UHI za 0,76 °C ujutro i porasta za 0,97 °C poslije podne. Optimalni radijus osjetljivosti omjera građevne čestice na ljetni UHI iznosi 230 m. Mehanizam reakcije omjera građevne čestice na UHI nastaje uglavnom zbog obujma pohranjene topline i zaustavljanja topline zračenja. Zaključak ove analize može pružiti podršku znanstveno teoretskom parametru u arhitektonskom dizajnu i urbanom planiranju i dizajnu.Plot ratio is an important indicator of architectural layout that affects urban heat island (UHI). Previous studies focus on street height/weight ratio, building density, and other indicators related to plot ratio but fail to effectively describe the time-space relationship between plot ratio and UHI and accurately guide the planning and design to reduce the UHI in the effective scale. The scale sensitivity method was proposed to study the time-space response of UHI to plot ratio to control the UHI intensity (UHII) caused by plot ratio during planning and design in a reasonable scale. The sensitivity of plot ratios in different space scales to UHI in the daytime was repeatedly calculated on 3S technology, MATLAB, SPSS, and other data analysis platforms based on the scale theory of landscape ecology and the method of geo-statistics analysis. The change curve of the response of plot ratio on UHI in the most sensitive space scale was discussed. The prevention and control standard of summer UHI was then constructed in accordance with the temperature in dog days of summer, human physiological reaction under high temperature, and relevant national regulations. The warning control was taken on the parameters of plot ratio on the basis of the temperature rise of UHI caused by plot ratio. Results show that scale sensitivity exists between plot ratio and UHI. In the daytime, the relationship between core plot ratio and summer UHI shifts from negative correlation to positive correlation. The temperature-rising effect in the afternoon is greater than the cooling effect in the morning. Core plot ratio has a linear relationship with summer UHII. The increase in the average core plot ratio reduces the UHII by 0,76 °C in the morning and increases it by 0,97 °C in the afternoon. The optimal sensitive radius of the core plot ratio on summer UHI is 230 m. The response mechanism of plot ratio on UHI is mainly due to heat storage volume and block to radiation heat. The study conclusion can provide scientific theoretical parameter support for architectural design and urban planning and design

    Long-lived magmatic evolution and mineralization resulted in formation of the giant Cuonadong Sn-W-Be polymetallic deposit, southern Tibet

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    The Cuonadong Sn-W-Be polymetallic deposit is the first Cenozoic leucogranite-related rare-metal deposit with giant metallogenic potential in the Himalayan orogen. However, controlling factors for the supernormal enrichment of beryllium, tin and tungsten in this deposit remain vague. In this study, we carried out systematic geochronological, whole-rock geochemical, and Sr-Nd isotopic analysis for the Cuonadong leucogranites, as well as detailed ore-forming geochronological analysis. The monazite U-Th-Pb, cassiterite U-Pb and muscovite Ar-Ar dating results, together with previously reported geochronological data, indicate that the major Cuonadong leucogranites (including, from old to young, weakly-oriented two-mica, two-mica granite and muscovite) were formed during ∼21-15 Ma, whereas the Sn-W-Be mineralization mainly occurred at ∼18-14 Ma. The Cuonadong leucogranites show strong peraluminous (A/CNK=1.09-1.22) features, and have high SiO2 (71.62-75.97 wt.%) and Al2O3 (14.04-16.09 wt.%) and low MgO (0.07-0.33 wt.%), MnO (0.01-0.15 wt.%) and total Fe2O3 (0.36-1.01 wt.%) contents, and are enriched in large ion lithophile elements (e.g., Rb, U, K, and Pb). These geochemical features together with enriched Sr-Nd isotopes (εNd(t) = -15.7 to -11.7; (87Sr/86Sr)i=0.71957-0.76313) indicate that the Cuonadong leucogranites belong to S-type granite and were derived from muscovite-induced dehydration melting of metapelites of the Higher Himalayan Crystalline Sequence. Perceptible linear variations of some major elements (e.g., Na2O, K2O, MnO, Fe2O3T, TiO2 and A/CNK) with increasing Rb/Sr ratios suggest these leucogranites experienced different degrees of evolution. Quantitative simulation calculations based on the whole-rock Rb, Sr, and Ba contents imply that the Cuonadong leucogranites experienced increasingly-strong fractional crystallization of plagioclase, K-feldspar and biotite from the weakly-oriented two-mica granite to two-mica granite and muscovite granite. Importantly, intense fractional crystallization leaded to notable enrichment of Sn, W and Be, although these elements are not obviously high in the relatively primitive magma for the Cuonadong leucogranites. Significantly, evident REE tetrad effects and deviation of twin-element pair ratios (K/Rb, K/Ba, Zr/Hf, Nb/Ta, and Y/Ho) from the chondritic values demonstrate that intense interaction between melts and F-rich aqueous fluids occurred during magmatic evolution. This implies that the Cuonadong leucogranites were derived from a volatile-rich magmatic system. The abundant volatiles probably remarkably facilitated and extended the fractional crystallization though lowering the solidus and viscosity of the magma. Thus, we propose that long-lived crystal fractionation (∼21-15 Ma) and mineralization (∼18-14 Ma) collectively leaded to supernormal enrichment of Sn, W, and Be in the Cuonadong Sn-W-Be polymetallic deposit. In contrast, the enrichment of Sn, W, and Be during the partial melting was insignificant.publishedVersio

    Spin excitations and the Fermi surface of superconducting FeS

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    High-temperature superconductivity occurs near antiferromagnetic instabilities and nematic state. Debate remains on the origin of nematic order in FeSe and its relation with superconductivity. Here, we use transport, neutron scatter- ing and Fermi surface measurements to demonstrate that hydro-thermo grown superconducting FeS, an isostructure of FeSe, is a tetragonal paramagnet without nematic order and with a quasiparticle mass significantly reduced from that of FeSe. Only stripe-type spin excitation is observed up to 100 meV. No direct coupling between spin excitation and superconductivity in FeS is found, suggesting that FeS is less correlated and the nematic order in FeSe is due to competing checkerboard and stripe spin fluctuations.Comment: 11 pages, 4 page

    Validating quantum-supremacy experiments with exact and fast tensor network contraction

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    The quantum circuits that declare quantum supremacy, such as Google Sycamore [Nature \textbf{574}, 505 (2019)], raises a paradox in building reliable result references. While simulation on traditional computers seems the sole way to provide reliable verification, the required run time is doomed with an exponentially-increasing compute complexity. To find a way to validate current ``quantum-supremacy" circuits with more than 5050 qubits, we propose a simulation method that exploits the ``classical advantage" (the inherent ``store-and-compute" operation mode of von Neumann machines) of current supercomputers, and computes uncorrelated amplitudes of a random quantum circuit with an optimal reuse of the intermediate results and a minimal memory overhead throughout the process. Such a reuse strategy reduces the original linear scaling of the total compute cost against the number of amplitudes to a sublinear pattern, with greater reduction for more amplitudes. Based on a well-optimized implementation of this method on a new-generation Sunway supercomputer, we directly verify Sycamore by computing three million exact amplitudes for the experimentally generated bitstrings, obtaining an XEB fidelity of 0.191%0.191\% which closely matches the estimated value of 0.224%0.224\%. Our computation scales up to 41,932,80041,932,800 cores with a sustained single-precision performance of 84.884.8 Pflops, which is accomplished within 8.58.5 days. Our method has a far-reaching impact in solving quantum many-body problems, statistical problems as well as combinatorial optimization problems where one often needs to contract many tensor networks which share a significant portion of tensors in common.Comment: 7 pages, 4 figures, comments are welcome
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