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Grinding force and temperature will affect the microscopic quality of workpiece surface and service life. Taking the cylindrical grinding of precision spindle bearings as the research object, the metamorphic layer of bearings of different brands was analyzed. Theoretical modeling and orthogonal test were carried out for the coupling of grinding force and grinding temperature of the outer ring surface of bearing. The surface roughness, residual stress, and retained austenite were analyzed. The grinding process of precision spindle bearing was optimized, and the fatigue life test of 6000 h was carried out and discussed. The results shown that (1) there were "dark layer" and "white layer" in the bearing surface, and the maximum thickness of "dark layer" was 12 μm, and the maximum thickness of "white layer" was 4.5 μm. (2) Feed speed had the greatest influence on grinding force. Grinding depth had the greatest influence on grinding temperature. Grinding wheel speed and grinding depth had the greatest influence on surface roughness. With the increase of grinding wheel speed, the tangential residual stress decreased, and the retained austenite increased instead. (3) The highest and lowest content of retained austenite was 9.9% (wheel speed: 40 m/s, workpiece speed: 5 r/min, grinding depth: 50 μm, feed speed: 0.6 mm/min) and 6.8% (wheel speed: 25 m/s, workpiece speed: 15 r/min, grinding depth: 40 μm, feed speed: 0.9 mm/min), respectively. (4) The fatigue failure of precision spindle bearings was caused by spalling, pitting, burning, and gluing. When the rotating speed was between 48,000 and 49,000 r/min, the temperature changes of the four bearings increased sharply. The temperature changes of the four bearings in each unit test were between 20 and 50℃. [ABSTRACT FROM AUTHOR]

Low-order feedforward controllers have attracted much attention in engineering applications due to their simple structure and easy implementation. This paper focuses on low-order feedforward controllers with closed-loop-injection architectures. Currently, the gain of this type of feedforward controller is tuned with the goal of accurately fitting the following error. However, due to the limited control bandwidth, the compensation signal generated by the feedforward controller cannot be fully responded to by the feed axis. This paper proposes a new gain-tuning method. It enhances the feedforward controller's performance by considering the axis dynamics. The effectiveness of the proposed method is verified by experiments implemented on a two-axis bench. The results show that, compared with the method that does not consider the axis dynamics, the proposed method further reduces the following error and the trajectory error during trajectory tracking. [ABSTRACT FROM AUTHOR]

China Overseas Economic and Trade Cooperation Zone (COCZs) which as a platform for China's foreign investment and trade has a potential impact on CO2 emissions, while strengthening bilateral investment and trade between China and the host countries. Since most of the COCZs are located in countries along the "Belt and Road," the purpose of this paper is to investigate the impact of COCZs on CO2 emissions of the countries along the "Belt and Road" and the mechanism of this impact. We constructed a panel data of 63 countries along the "Belt and Road" from 2000 to 2020, and conducted an empirical study using the difference-in-difference (DID) model. Our research result show that COCZs can significantly increase the CO2 emissions of the countries along the "Belt and Road." Then, we conduct a series of robustness tests and endogeneity test on the estimation results of the baseline model, and the results of the tests all support the conclusion reached by the baseline model. Our heterogeneity analysis reveals that the effect of COCZs on CO2 emissions is more significant in Asian countries with lower national income or industrialization and higher country risk. Finally, we analyzed industrial value added and energy depletion as possible impact mechanisms, the results of mechanism model shows that COCZs can increase the industrial value added and then significantly increase CO2 emissions, but energy depletion was not an efficient mechanism. Our paper provides a new insight into the impact of bilateral economic and trade cooperation zones on CO2 emissions in host countries. [ABSTRACT FROM AUTHOR]

Geometric error compensation is important in improving the machining accuracy of five-axis machine tools. To improve the efficiency of real-time compensation, this paper proposes a novel compensation method based on a novel representation of the volumetric error. First, 5 error parameters in the workpiece-tool coordinate system are employed to describe the volumetric error, simplifying the actual reverse kinematics from an overdetermined problem to a well-determined problem. Second, the actual inverse kinematics solution, neglecting the position-varying feature of geometric errors, is derived by a simple operation. Finally, the actual inverse kinematics solution considering the position-varying feature of geometric errors is derived based on a linear approximation of geometric errors at the command position nearby. Compared with traditional compensation methods, the proposed method could guarantee higher efficiency since it has a concise analytical expression. Simulation and experiment results are then illustrated to validate the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

Bearing is one of the essential and important components in high-end equipment. In this study, the spindle precision bearings, RV reducer thin-walled bearings and high-speed rail bearings produced by different manufacturers were used as research carriers. The element content, grain size, grain boundary morphology, metamorphic layer and hardness of the bearing raceway, fatigue life test for 42 h were compared and analyzed. The theoretical model of influencing factors of bearing service life was deduced, and the raw materials, processing technology and service life of bearing were discussed in multiple dimensions. The following conclusions were obtained: (a) The bearings produced by German and Japanese manufacturers were more accurately controlled in heat treatment of the raw material and ultra-precision machining process. (b) The bearings produced by Chinese and American manufacturers have their own advantages in service life. (c) With the increase of torque, friction factor and wear amount will increase, wear resistance and fatigue life of bearings will decrease. (d) With the increase of the hardness of the bearing raceway, the wear amount will decrease, the wear resistance and the fatigue life will increase. (e) With the decrease of the metamorphic layer in the bearing raceway, the compressive stress will increase, the wear amount will decrease, and the wear resistance and the fatigue life will increase. Through the analysis of this study, we hope to provide product quality control methods for bearing enterprises. [ABSTRACT FROM AUTHOR]

To explore the current state of research on off-label drug use in children and identify the existing research gaps in this topic. Six literature databases were searched to identify studies focusing exclusively on off-label drug use in children (aged < 18 years) published in Chinese or English between 2016 and 2021. We also searched clinicaltrials.gov for pediatric clinical trials conducted in the same period and compared the numbers of studies on off-label use and clinical trials for the most commonly reported drugs and drug types. Our search revealed 568 studies on off-label drug use. Almost half of the studies (n = 240) were cross-sectional. A total of 212 specific drugs or drug types were addressed in 361 studies, the most frequent being antipsychotic agents (n = 12), dexmedetomidine (n = 10), and rituximab (n = 8). Antipsychotic agents were also the most common type of drug examined in clinical trials in children. We identified a total of 435 different types of off-label use, the top three being unapproved indication (n = 157), population (n = 96), or age (n = 36). Only about one-third of the studies reported collecting informed consent (n = 195) or having ethics committee approval (n = 166).    Conclusions: Off-label use of antipsychotics in children is widely reported in the literature. We suggest pediatric researchers to consider the number of studies on off-label use and existing clinical trials on different drugs when selecting target drugs for new studies and systematic reviews. What is Known: • There exist a large number of studies on off-label drug use in children. What is New: • This is the first scoping review of studies on off-label drug use in children. • Off-label use of antipsychotic agents is widely reported. [ABSTRACT FROM AUTHOR]

The purpose of this systematic review is to evaluate the efficacy and safety of using potential drugs: remdesivir and glucocorticoid in treating children and adolescents with COVID-19 and intravenous immunoglobulin (IVIG) in treating MIS-C. We searched seven databases, three preprint platform, ClinicalTrials.gov, and Google from December 1, 2019, to August 5, 2021, to collect evidence of remdesivir, glucocorticoid, and IVIG which were used in children and adolescents with COVID-19 or MIS-C. A total of nine cohort studies and one case series study were included in this systematic review. In terms of remdesivir, the meta-analysis of single-arm cohort studies have shown that after the treatment, 54.7% (95%CI, 10.3 to 99.1%) experienced adverse events, 5.6% (95%CI, 1.2 to 10.1%) died, and 27.0% (95%CI, 0 to 73.0%) needed extracorporeal membrane oxygenation or invasive mechanical ventilation. As for glucocorticoids, the results of the meta-analysis showed that the fixed-effect summary odds ratio for the association with mortality was 2.79 (95%CI, 0.13 to 60.87), and the mechanical ventilation rate was 3.12 (95%CI, 0.80 to 12.08) for glucocorticoids compared with the control group. In terms of IVIG, most of the included cohort studies showed that for MIS-C patients with more severe clinical symptoms, IVIG combined with methylprednisolone could achieve better clinical efficacy than IVIG alone. Conclusions: Overall, the current evidence in the included studies is insignificant and of low quality. It is recommended to conduct high-quality randomized controlled trials of remdesivir, glucocorticoids, and IVIG in children and adolescents with COVID-19 or MIS-C to provide substantial evidence for the development of guidelines. What is Known: • The efficacy and safety of using potential drugs such as remdesivir, glucocorticoid, and intravenous immunoglobulin (IVIG) in treating children and adolescents with COVID-19/MIS-C are unclear. What is New: • Overall, the current evidence cannot adequately demonstrate the effectiveness and safety of using remdesivir, glucocorticoids, and IVIG in treating children and adolescents with COVID-19 or MIS-C. • We are calling for the publication of high-quality clinical trials and provide substantial evidence for the development of guidelines. [ABSTRACT FROM AUTHOR]

The beryllium bronze guide sleeve and the aluminum alloy valve body are assembled to form a beryllium bronze-aluminum alloy stepped hole which requires multiple positioning and tool changes during machining, resulting in lower machining efficiency and accuracy. The geometry error and surface quality of beryllium bronze-aluminum alloy stepped holes after reaming were studied in this research. The geometric error (cylindricity, concentricity and verticality) and diameters of the stepped holes were measured by using a three-coordinate measuring machine. The experimental results show that the PCD forming cutters has high geometric error and diameter stability when reaming beryllium bronze-aluminum alloy stepped holes. Under various cutting parameters, the cylindricity of stepped holes was guaranteed to be within 6μm, and the concentricity of stepped holes was guaranteed to be within 6μm, and verticality of stepped holes was guaranteed to be within 2μm. With the increase of spindle speed and feed per tooth, the diameters of beryllium bronze holes increase while the diameters of aluminum alloy holes decrease and then increase. As the cutting allowance increases, the diameters of the beryllium bronze holes and aluminum alloy holes decrease. The laser confocal microscope and scanning electron microscope were used to detect and analyze the surface quality of beryllium bronze-aluminum alloy stepped holes after reaming. The experimental results show that the surface roughness of the beryllium bronze-aluminum alloy stepped holes reamed by using the PCD forming cutter were less than 0.3μm, and the surface roughness of the beryllium holes were slightly larger than the aluminum holes. The fourth group of experimental parameters (spindle speed 1290r/min, feed per tooth 0.01mm/z, cutting allowance 0.06mm) was selected as the actual processing parameters. There are cavities on the surface of the initial stepped holes before reaming and the cavities basically disappear after reaming, so the surface quality of the beryllium bronze-aluminum alloy stepped holes has been greatly improved. [ABSTRACT FROM AUTHOR]

This paper proposed a new guideway base structure of hydrostatic guideways to flatten its spatial temperature variation characteristics. Four oil storage holes penetrating through the base are used to collect the hydraulic oil, which is heated by power losses after oil flows through the bearing clearances. When the heated oil flows into the four oil storage holes, the whole base is warmed and temperature distribution non-uniformity is avoided. In order to verify the effectiveness of the new structure, a physical model of the guideway base simplified from actual base was developed. A thermal model of a guideway base was developed using the finite element method (FEM). The temperature distribution of guideway bases was calculated, taking into account the temperature-dependent heat transfer coefficients of interfaces and thermal contact conductances. Analysis of temperature differences, thermal equilibrium time, and temperature uniformity of bases demonstrates the effectiveness of the new base design on its thermal characteristics and improves structural parameters. The experimental results verify the accuracy of the thermal model hydrostatic guideway bases. [ABSTRACT FROM AUTHOR]

This study mainly measures the accuracy of closed impeller machining machines in aerospace. However, this machining center is different from others and belongs to a "cradle type" five-axis machining center. The measuring difficulty of cradle-type five-axis machining center is that the error accuracy of X, Y, Z, B, and C axes can meet the requirements when the Y-axis moving speed reaches 80 m/min and the maximum acceleration is 10 m/s2; and the C-axis maximum angular acceleration is 1.25 rad/s2; and the maximum angular velocity is 60 rpm. Therefore, the 24 theoretical models of accuracy error measurement for cradle type are derived at first. Combined with the theoretical model, the straightness of X, Y, and Z and the positioning accuracy of X, Y, Z, B, and C axes are measured by laser interferometer. In X, Y, Z, and C axes detection, two methods are adopted and compared. Then, the overall processing accuracy is measured through trial-cutting parts. The measurement results show that the second way (with temperature sensor) is better than the first measurement. Compared with the device without normal temperature sensor, the measurement of X-axis repeated positioning accuracy and positioning accuracy are improved by 8.5% and 23.6%, respectively. The positioning accuracy of Y-axis is improved by 16.7%. The repeated positioning accuracy and positioning accuracy of Z-axis are improved by 78.9% and 72.1%, respectively. The repeated positioning accuracy and positioning accuracy of the C-axis are improved by 20.4% and 7%, respectively. At the same time, it is also measured that the repeated positioning accuracy of B-axis is 15 μm. Finally, through the processing and testing of the trial-cutting parts, the processing error of the inclined cone table profile is 20 μm, which is far less than the design parameters of the original cradle-type five-axis machine tool. It provides efficient theoretical guidance and practical reference for similar five-axis machine tool measurement methods in the future. [ABSTRACT FROM AUTHOR]

This paper mainly analyzes and experiments the processing technology of high speed (12000 r/min) and large proportion thin-wall parts (thickness/width = 1:80 and thickness/height = 1:120), so as to guide the machining of closed centrifugal impellers in aerospace. In this process, low melting point alloy is selected as the filling material to increase the rigidity of thin-walled parts and improve the indicated roughness of parts. Different low melting point alloy filling structures are carried out on large proportion of thin-wall sample parts. In addition, an auxiliary angle R is added at the stress concentration of the part itself to reduce the vibration caused by the machining path. For the results of simulation and test, the parts without filling low melting point alloy can not be processed and used at all, while the "tower" filling structure has fine cracks at the top of the thin-walled parts. The "column" filling structure increases the rigidity by about 19.97 % and the roughness by about 50 %. [ABSTRACT FROM AUTHOR]

Aims: We aim to systematically review the existing guidelines on physical activity for T2DM and assess the consistency of their recommendations, methodological quality, and reporting quality. Methods: We performed a literature search on PubMed, China Biology Medicine disc, and four main guideline databases in order to identify existing T2DM guidelines. We then evaluated the methodological and reporting qualities of the guidelines using the AGREE II instrument and the RIGHT checklist. Fifteen guidelines were included in total, with eight of these (53.33%) assessed being "recommended" and five graded as having good reporting quality. Result: A total of 30 physical activity recommendations were extracted. Fifteen recommendations reported the levels of evidence, and of these, five were found to be based on a high quality of evidence. Aerobic exercise at least 3 days per week was recommended by most guidelines (10/15, 66.67%). Eight guidelines (53.33%) recommended resistance exercise, while combined aerobic and resistance exercise was recommended in three of the guidelines (20.0%). Only two guidelines recommended supervised exercise, and one recommended flexibility exercise. Four of the guidelines (26.67%) solely recommended physical activity or exercise, but with no added details. Conclusions: The quality of the guidelines concerning physical activity for T2DM was found to be moderate to low and varied substantially. Recommendations regarding physical activity for T2DM are not very specific or clear and remain incompletely consistent, while the level of evidence and the strength of the recommendations were seldom reported. Our findings suggest a need for guidelines for diabetes based on high levels of evidence. [ABSTRACT FROM AUTHOR]

Volumetric error is a primary factor that affects the accuracy of machining tools. The ability to ascertain volumetric error in a rapid and simple manner is of significant importance, and this can remarkably reduce the probability of temperature variation during the experiment. This study proposes a strategy for volumetric error measurement and compensation based on laser tracer for the 3-axis numerical control (NC) machining tool, and verifies the machining accuracy of a concave semi-spheroid test piece. In this study, the calibration methods employed by the laser tracer and the error separation algorithm of the machining tool are initially investigated. Following this, the accuracy of the geometric error measurement is verified using the laser interferometer. The cubic spline interpolation method is then employed to establish the tool path volumetric error model in the 3-axis NC machining tool, and the G-code modification is conducted for volumetric error compensation. Experiment results show that when the error compensation is performed, the improvement in the accuracy as compared with the initial state exceeds 50% not involving machining. To evaluate the accuracy and effectiveness of the proposed method, two machining tests to obtain a concave semi-spheroid test piece with and without volumetric error compensation strategy are studied, and the corresponding accuracies are measured by a high precision coordinate–measuring machine. It is found that the machining accuracy after having performed the error compensation is approximately 43% higher than that obtained on the pre-volumetric error compensation. [ABSTRACT FROM AUTHOR]

Background: Several antiviral agents licenced for blocking mother-to-child transmission (MTCT) of HBV, but their relative efficacy beginning from different trimesters has scarce been evaluated. We aimed to conduct a network meta-analysis to statistically differ the efficacy and safety of each antiviral agents initiating on different timings in preventing mother-to-infant transmission of HBV. Methods: Studies were included from PubMed, EMBASE, Web of Science, and Cochrane databases through July 1, 2019. Eligible studies recruited randomized controlled trials and nonrandomized studies reporting about infant or/and maternal efficacy and safety outcomes and were screened by two investigators independently. Extracted data were analyzed by pair-wised and network meta-analysis, respectively. Results: 3 Randomized and 32 nonrandomized studies enrolling 6738 pregnant female were included. Using network analysis, any antiviral agent interrupted HBV vertical transmission much more effectively than placebo. No agent showed significant efficacy different from others, but a strong trend toward significance was found in telbivudine and tenofovir, of which had the highest probability of being ranked the first- or second-best treatment for reducing MTCT of HBV. The treatment applied in the first and second trimester had a similar efficacy in preventing MTCT. Compared with the initiation during the third trimester, lower rate of MTCT was revealed when antiviral therapy was administrated before third trimester, (RR = 0.045, 95% CI 0.0053 to 0.20); a similar effect at delivery on suppressing maternal HBV DNA level and converting serum HBeAg were achieved if the timing of antiviral treatment started prior, but an obvious improvement of normalizing ALT flare was calculated out; no statistically differences among maternal and fetal safety outcomes were found if mothers received antiviral agents before pregnant 28 weeks. Conclusion: This network meta-analysis recommended the earlier use of telbivudine or tenofovir, tends to be better to prevent MTCT of HBV in pregnancy with no increased adverse maternal or fetal outcomes. [ABSTRACT FROM AUTHOR]

Closed hydrostatic rotary table is one of the key units in an ultra-precision machine tool, while the main component of the rotary table is the rotor system, consisting of two thrust plates and a rotor. The kinematic errors of the rotary table are directly affected by the geometric errors of the rotor system. However, geometric errors of the rotor system are difficult to evaluate, due to the closed structure of the system. In this paper, a strategy to evaluate geometric errors of rotor system, using ultra-precision CMM (coordinate measuring machine), is presented. The method is based on coordinate conversion and least squares principle. In this approach, two sets of open structures are established, by dividing the rotor system into two parts. The profiles and cylindrical feature of the components of the rotor system are directly scanned by CMM. Following the compensation of the data from the CMM, the parallelism and perpendicularity errors can be evaluated. Furthermore, based on the aforementioned compensation algorithm, an optimization method for improving assembly precision of the rotor system is proposed. The result shows perpendicularity error between the two thrust plates and the rotor to be 14 μm and 21 μm, respectively, and the parallelism error between the two thrust plates to be 28 μm with measurement uncertainty of 0.5 μm. Additionally, the experimental result on the optimization method of guiding the assemblage of rotor system indicates that the parallelism error reduced to 12.1 μm, noting a 57% improvement. [ABSTRACT FROM AUTHOR]

Objective: Reporting Items for Clinical Practice Guidelines (CPGs) in HealThcare (RIGHT) checklist was used as a tool to assess the reporting quality of 2014–2018 CPGs on diabetes treatment, aiming to promote the application of RIGHT and improve the reporting quality of future guidelines. Methods: We searched Chinese Biomedical Literature Service System (CBM), China National Knowledge Infrastructure (CNKI), Wanfang Data, VIP database, Medline, Embase, Allied, and Complementary MEdicine Database (AMED), and Medlive and Google Scholar (Google academics), and collected published CPGs on diabetes with published date during 1st January, 2014 and 7th November, 2018. CPGs on diabetes issued since 2014 were included and filtered by two reviewers independently. Then the basic information extraction and RIGHT evaluation of the included CPG are carried out. Results: A total of 34 guidelines were included, out of which 7 are for Chinese and 27 for other countries. Overall, basic information (domain 1) got the highest (64.66%) reporting rate, while financing and conflict-of-interest statements and management (domain 6) got the lowest (8.1%). For all guidelines, classification of guidelines (item 1c) was sufficiently reported, and description of the specific sources of funding for all stages of guideline development (item 18a) was not reported. For Chinese CPGs, financing and conflict-of-interest statements and management (domain 6) was most insufficiently reported, and only identification of guideline in the title (item 1a), corresponding information of the developer or author (item 4), description of basic epidemiology (item 5), and subgroup description (item 7b) out of 22 items were better reported than foreign guidelines. Conclusions: Overall, the CPGs on diabetes during 2014–2018 adhered to ~41% RIGHT checklist, of which Chinese CPGs adhered less than that of foreign guidelines. It is suggested that the RIGHT reporting checklist should be endorsed and used by CPG developers to ensure higher quality and adequate use of guidelines. [ABSTRACT FROM AUTHOR]

In high-speed precision machining, the spindle balance state may be altered by re-clamping of the workpiece or tool changes, as well as a number of other reasons. Therefore, repeating the dynamic balancing process on-site after any changes have been made to the spindle system is of utmost importance. This paper proposes a new method for balancing rigid motorized spindles based on the real-time position data of CNC machine tools with the aim of reducing the costs associated with external balancing instruments and improving the efficiency of the dynamic balancing process. Moreover, the proposed technique can be integrated into CNC controllers and data such as the amplitude and phase angle of spindle can be extracted based on the real-time position of linear axis with the feed direction perpendicular to the spindle axis. The speed of the spindle and the reference position of the correction masses can then be calculated using the index pulse of the spindle measurement system and unbalanced spindle data. The dynamic balancing system was shown to accurately identify sensitive processing speeds of motorized spindles, which is crucial to high-speed high-precision machining. Finally, the feasibility and the stability of the spindle dynamic balancing system were experimentally validated using an LDT500 ultra-precision diamond turning. The roughness of the machined surface was shown to decrease from 25.2 to 5.9 nm and thus, verifies the feasibility of applying spindle dynamic balancing system in practical engineering. [ABSTRACT FROM AUTHOR]

Purpose: To systematically evaluate the quality, consistency and the evidence support of guidelines for perioperative diabetes management.Methods: We retrieved guidelines through systematic search, critically evaluated their quality and compared the recommendations of included guidelines. Five aspects were compared: target level, management of hyper- and hypoglycaemia, frequency of monitoring, management of insulin, and management of oral anti-diabetic drugs (OADs).Results: Fourteen guidelines met our criteria, and 342 recommendations were extracted, the results of Appraisal of Guidelines for Research and Evaluation II (AGREE II) evaluation showed that none of the mean score in each domain was higher than 50%. On average, most guidelines had only one domain scored above 50%. Most recommendations (78.9%) did not specify their supporting evidence, 71 (20.8%) were formed using grading criteria, none cited systematic review or meta-analysis. Recommendations were inconsistent across different guidelines.Conclusions: The existing guidelines about perioperative management of diabetes needs improvement in methodology, as well as the production of evidence with high quality. Evidence-based guidelines are required for the perioperative management of diabetes. [ABSTRACT FROM AUTHOR]

Numerous systematic reviews investigating the effects of mesenchymal stem cells (MSCs) in treating knee osteoarthritis (OA) have been published with controversial conclusion. The purpose of the overview was (1) to perform an overview of systematic reviews investigating MSCs for knee OA and (2) to synthesize evidence qualitatively to assess confidence in the review findings. A systematic search of systematic reviews published through Aug 2017 was conducted using the MEDLINE, EMBASE and Cochrane Library. The methodological quality and risk of bias of included systematic reviews was assessed by AMSTAR instrument and ROBIS tool, respectively. Best evidence choice procedure was conducted according to the Jadad decision algorithm. The systematic reviews with high methodological quality and low risk of bias were selected ultimately for further evidence synthesis based on the CERQual tool. Four systematic reviews were eligible for inclusion. According to the ROBIS tool, there was one systematic review with low risk of bias and three with high risk of bias. Thus, only one systematic review conducted by Pas et al. with highest AMSTAR score and low risk of bias was selected. For all outcomes after evidence synthesis via the CERQual tool, confidence for decision making was either low (self-reported measurement and MRI/histological outcome) or moderate (adverse events). The present study demonstrates that moderate confidence could be placed in safety of MSCs therapy for knee OA, but with low confidence in efficacy outcomes due to limitations of the current evidence. Further high-quality studies with high internal and external validity are still required. [ABSTRACT FROM AUTHOR]

To improve the grinding process towards a higher surface integrity, in this study, an orthogonal test was designed and conducted to determine the effect of the wheel speed, workpiece speed, and the grinding depth on the surface integrity of a bearing raceway. After the grinding process, the residual stress, the residual austenite content, the surface hardness, the thickness of the affected layer, the surface roughness, and other properties were measured, and a parametric characterization of the surface integrity of the raceway was performed. Using the results of the orthogonal test as training samples, two support vector machine (SVM) models were established, and the prediction accuracy was tested through cross-validation. Finally, the step size search method was used starting at the optimal grinding parameters obtained through the orthogonal test, and the grinding parameters were further optimized using the two SVM models. The results showed that combining an orthogonal test with an SVM model can effectively shorten the time required for optimizing the grinding process, and that a global optimum can be obtained for the surface integrity. [ABSTRACT FROM AUTHOR]

Hydrostatic guideways have various applications in precision machine tools due to their high motion accuracy. The analysis of motion straightness in hydrostatic guideways is generally ignoring the external load on the slider. A variation force also exists, caused by the different working positions, together with the dead load of the slider and that of other auxiliary devices. The effect of working position on vertical motion straightness is investigated based on the equivalent static model, considering the error averaging effort of pressured oil film in open hydrostatic guideways. Open hydrostatic guideways in LGF1000 are analyzed with this approach. The theoretical results show that the slider has maximum vertical motion straightness when the working position is closer the guiderail of Y axis. The vertical motion straightness reaches a minimum value as the working position is located at the center of the two guiderails on the Y axis. The difference between the maximum and minimum vertical motion straightness is 34.7%. The smaller vertical motion straightness is attributed to the smaller spacing of the two pads centers, along the Y direction. The experimental results show that the vertical motion straightness is 4.15 μm/1200 mm, when the working position is located in the middle of the X beam, and 5.08 μm/1200 mm, when the working position is approaching the Y guiderails, denoting an increase of 18.3%. The changing trends of the measured results validate the correctness of the theoretical model. The research work can be used to reveal the variation law of accuracy of the open hydrostatic guideways, under different working positions, to predict the machining precision, and provides the basis for an error compensation strategy for gantry type grinding machines. [ABSTRACT FROM AUTHOR]

In the production process of aeronautical thin-walled parts, under the influence of cutting force, clamping force, cutting chatter, and other factors, thin-walled parts are particularly prone to vibration and instability phenomena. Thus, it is hard to guarantee machining accuracy. In this paper, a special fixture using low-shrinkage of low-melting-point alloy to clamp thin-walled parts was designed. The physical properties of low-melting-point alloy were studied. The experimental results showed that the alloy with melting point of 70 °C is suitable for clamping the thin-walled part. A typical aeronautical thin-walled part was selected, and the corresponding milling process was adopted. Then, the overall structural design of the fixture is accomplished. The machining experiment results showed that the workpiece milled with this special fixture has high accuracy and low removal rate. [ABSTRACT FROM AUTHOR]

Due to the error averaging effect of pressured oil film in hydrostatic guideways, motion straightness of the slider is smaller than the profile error of guide rails. In spite of this, structural parameters of the guideway system have dramatic effects on the error averaging coefficient. Therefore, it is necessary to investigate the relationship between the structural parameters of the guideway system and slider motion straightness. In this paper, effect of the ratio ( m) of pad center spacing to guide rail profile error wavelength on motion straightness was the primary focus. A static analysis model based on the error averaging effect considering pad center spacing in open hydrostatic guideways with four pads was established. Linear displacement motion error of the slider with different system structural parameters was solved, and slider motion straightness was calculated using least-square method. A grinding machine LGF1000 was used in experiments, and the slider vertical motion straightness was improved to 0.98 μm/600 mm from 2.08 μm/600 mm after using the lapping process on a specific guide rail along the Y-axis for change the m. In addition, precision was improved by 52.9 %. Results show that m has significant influence on vertical motion straightness of the slider. Increasing the pad center spacing m allows a reduction in motion straightness for m equal or lesser than 0.5. However, a decrease in the pad center spacing is useful to decrease the motion straightness, when m is equal or larger than 0.72. [ABSTRACT FROM AUTHOR]

The aim of this systematic review and meta-analysis is to assess the efficacy and safety of tofacitinib for the treatment of patients with acute rheumatoid arthritis (RA) who have had an inadequate response to disease-modifying antirheumatic drug (DMARD). Randomized controlled trials were searched in MEDLINE (1966-2013), Embase (1947-2013), the Cochrane Central Register of Controlled Trials (1948-2013), WHO International Clinical Trial Registration Platform (2004-2013), Clinical Trial.gov (1999-2013), and China Biology Medicine disc (1978-2013). The review included 10 studies involving 4,929 patients. A pooled analysis of six studies showed that tofacitinib had a superior effect over placebo (both with background therapy) at weeks 12 and 24. Also, the pooled results of three studies showed that tofacitinib monotherapy had a significantly greater effect over placebo. Compared to adalimumab, tofacitinib was found to be more efficacious as well. For safety, tofacitinib monotherapy had less serious adverse events (sAE) than placebo but not other adverse effects (oAE). In the comparison of tofacitinib and placebo both with background therapy, no difference in sAE and oAE were found. However, the quality of the evidence was quite low when evaluated using GRADE. Tofacitinib alone, or together with non-biologic DMARDs, was associated with more favorable remission in the signs and symptoms of RA than adalimumab or placebo. Also, tofacitinib monotherapy was safer than placebo with regards to reported sAE, but not oAE. However, the quality of evidence is exceedingly low; long-term, large-scale, and high-quality post-marketing research is suggested to further verify the conclusion. [ABSTRACT FROM AUTHOR]

A letter to the editor is presented in response to the article "Plate Fixation Versus Intramedullary Fixation for Displaced Mid-Shaft Clavicle Fractures: A Systematic Review" by R. M. Houwert et al in the 2012 issue.