Ar Ratio Research Articles

An LES study of the wake flow dynamics and heat transfer characteristics of two side-by-side finite wall-mounted square cylinders

This paper studies the wake flow dynamics and heat transfer characteristics of two side-by-side finite wall-mounted square cylinders through large-eddy simulations at Reynolds and Prandtl numbers of Re = 1.2 × 104 and Pr = 0.7. The influence of normalized center-to-center distances between cylinders (S/d, where d is the side of the cylindersʹ cross-section) is investigated for S/d = 2–5, while both cylinders pose an identical aspect ratio of AR = 7. First, the numerical approach is validated against the published experimental data. Then the instantaneous and time-mean wake flow structures, as well as the global quantities, turbulence statistics and heat transfer are studied. It is found that the biased/flip-flop flow at S/d = 2 turns into anti-phase coupled vortex shedding flow at S/d ≥ 3. This flow regime transition induces a relatively sharp change in drag coefficient and vortex shedding frequency, minimum values at S/d = 2 and maximum values at S/d = 3. The Nusselt number mildly changes at S/d ≥ 3. The turbulent deflected gap flow at S/d = 2 results in inequality of drag forces on and heat transfer from two cylinders. That is, the drag coefficient and Nusselt number are larger for the cylinder towards which the gap-flow is deflected. It is also shown that swinging the deflected gap flow at S/d = 2 is a more intense source of turbulence than the vortex shedding from lateral faces, albeit the Reynolds stress is magnified with increasing S/d. The flow interference is steadily reduced with S/d, almost faded at S/d = 5.

Relationship between aromatic hydrogen and aromatic carbon in straight run and converted oils

In the conversion of high boiling oil fractions, it is difficult to track compositional changes that affect the chemical nature of species. For reaction engineering, monitoring changes related to hydrogen transfer reactions and formation of aromatic species as thermal conversion progresses to coking is useful. Proton and carbon-13 nuclear magnetic resonance (1H and 13C NMR) spectrometry can measure the aromatic hydrogen and aromatic carbon content in oils of diverse origin and distillation range. 13C NMR analyses are more time consuming than 1H NMR analyses. The ability to calculate the aromatic carbon content of oils directly from measured aromatic hydrogen content is alluring and is reportedly feasible (Cookson, et al. Fuel 1986; 65:1247–1253). In this work previously reported 1H and 13C NMR data for different petroleum and coal derived oils were collated and supplemented with experimental measurements that included narrow cuts of straight run and refined oils, as well as bitumen-derived mixtures that were thermally converted at different levels of severity. It was found that aromatic carbon content, CAr, was only broadly related to aromatic hydrogen content, HAr. A wide range of values for CAr was possible for a specific value of HAr. The medium atmospheric equivalent boiling point temperature, T50, was a poor descriptor for indicating a directional change in the relationship between CAr and HAr, both for wide and narrow boiling range distillation fractions. An increase in heterocyclic aromatic content caused a decrease in the (H/C)Ar ratio, since heteroatoms in aromatics are mainly found in ring-edge and not in ring-junction positions. When the changes in HAr and CAr of different bitumen-derived materials with respect to thermal conversion severity were evaluated, it was found that changes in HAr and CAr were not in a fixed relation to each other.

Analysis of vibration mitigation for CFG pile-supported subgrade of high-speed railway

Ground vibrations due to a train moving on the pile-supported subgrade are investigated using a 2.5-dimensional finite element model (2.5D FEM). The equivalent pile wall approach is used to model the piles and soils. Two types of subgrades, with or without cement fly-ash gravel (CFG) piles, are analyzed to evaluate the performance of CFG pile-supported subgrade in mitigating ground vibration. The effects of area replacement ratio aR and pile-soil stiffness ratio Sps on vibration mitigation performance are studied. Results show that the CFG pile-supported subgrade exhibits positive performance in vibration mitigation, and this performance gets better away from the track than near it. The improved subgrade could elevate the critical speed, and the resonance-like amplification of ground vibration as the train runs at the critical speed for the unimproved subgrade is completely excluded. Increasing either the aR or Sps can enhance the vibration mitigation performance. However, there are the critical values of aR = 8.70% and Sps = 138.89, beyond which the vibration reduction performance would no longer be improved.

Ultralow Macroscale Friction and Wear of MoS2 in High‐Vacuum Through DC Pulsing Optimization, Nitridization, and Sublayer Engineering

AbstractThe reliability and durability of devices that operate in vacuum and are subjected to wear are critical issues. The concerns rise at the macroscale wherein the contact area is large, yet the contact stress is in the GPa range. This paper reports on the design and fabrication of a coating comprising nitridized molybdenum disulfide (MoSN) supported by a novel nanolayered coating composed of carbon with subnanometer‐thick periodic albeit discrete Cr interlayers. The MoSN coatings are deposited onto mating surfaces using pulsed‐DC magnetron sputtering in an atmosphere with varying N2 to argon (Ar) ratios. Pulsed‐DC parameters, such as pulse duty and frequency, together with nitrogen content, are systematically optimized to achieve superior mechanical and tribological properties. The results reveal the importance of optimizing pulsing parameters during deposition as they significantly alter the properties of MoS2. The outcome is fabrication of a coating that despite having a low thickness, exhibits extremely low friction and record‐breaking macroscale wear rate in high vacuum compared to the values reported in the literature by date. Lastly, the analysis confirms the prediction of theoretical studies regarding the release of entrapped nitrogen in gaseous form during the wear process without disrupting the formation of a stable solid lubricant tribofilm.

In situ and in vitro evaluation of the bioavailability of rumen-protected methionine with coating prototypes

Rumen protected amino acids are supplements that can enhance ruminal performance, yet the coating designed to protect the amino acids might also lead to different effects. Methionine is an essential methyl donor to synthesize protein, and little data exists on the effects of coating materials on its bioavailability. The purpose of this study was to estimate the effect of rumen-protected methionine (RPM) coatings with different ratios of acrylic resin IV (AR), ethyl cellulose (EC), and a mixture of AR and EC (AREC). Fifteen RPMs were prepared according to a single factor design, with 5 proportions each of AR, EC, and AREC to DL-methionine (DL-Met). Twelve hybrid small-tailed Han sheep with rumen fistula were utilized to evaluate in situ escape of RPMs, followed by in vitro abomasum-intestinal release of the RPMs. The results showed a regular variation in both ruminal disappearance and gastrointestinal release of RPMs with different coating prototypes and retention time. The RPMs that were EC and AREC coated presented high bioavailability compared to those with AR. Bioavailability of RPMs was optimal with the 2:20 AREC: DL-Met ratio, when the proportion of AR:EC is 1:1. Additionally, RPMs with a 1:3 ratio of AR:EC confirmed the optimum effect for the RPM of 2:20 AREC: DL-Met. In conclusion, an RPM with a lower AREC ratio coating can achieve better bioavailability and is synergistic to those with EC and AR.

A unified method for measuring noble gas isotope ratios in air, water, and volcanic gases via dynamic mass spectrometry

We describe a new method for the purification, transfer, and analysis of heavy noble gas isotope ratios in water, air, or volcanic gas samples using a dynamic dual-inlet isotope-ratio mass spectrometer (IRMS). IRMS noble gas analysis offers the potential for orders-of-magnitude higher precision than traditional (static) noble gas mass spectrometry. However, due to both inherent IRMS requirements and challenges associated with sample collection and purification, measuring noble gases via IRMS has typically been limited to samples with an air-like elemental composition. Our new method allows for highly accurate and precise measurements of Ar, Kr, and Xe isotope ratios via IRMS, independent of sample composition, thereby opening the door to air, water, or volcanic gas analyses all made with the same technique. This approach exploits the fact that purified heavy noble gas samples are dominated by 40Ar, such that matching 40Ar ion beams between sample and reference gas streams results in pressure balancing. We further introduce new techniques for precisely quantifying and correcting for (i) Kr and Xe isotope non-linearity and matrix effects, (ii) interference of the low energy 40Ar tail on 36Ar and 38Ar ion beams, and (iii) the impact of short-term background fluctuations on trace Xe isotope measurements. We also present results from adsorption-desorption experiments with multiple adsorbent materials across a range of temperatures. For adsorption on silica gel, we find small equilibrium isotopic fractionation of Kr (εeq = −0.37 ± 0.04‰ amu−1, ±2 SE) and Xe (εeq = −0.06 ± 0.02‰ amu−1, ±2 SE) that may be relevant to studies of terrestrial Xe isotope signatures. We demonstrate that adsorption and desorption of heavy noble gases on silica gel at 77 K and 303 K, respectively, is highly reproducible and thus constitutes a viable and efficient method for transferring gases without reliance on cryostats or liquid helium.

CO2 decomposition using the coaxial dielectric barrier discharge: effect of additive gas and double outer electrodes

This work has studied CO2 decomposition through the dielectric barrier discharge (DBD). The configuration of the DBD reactor was performed as a coaxial DBD tube. The dielectric barrier was made of a quartz tube with 1 mm thickness, while an outer electrode was made of a copper flat sheet wrapping around a quartz tube. The coaxial axis was made of stainless steel rod to be an inner electrode. The power source was applied by the alternative current (AC) high voltage with 7.8 kHz of frequency to both electrodes of the plasma reactor. The experiment was conducted on various conditions such as a mixed gas ratio, discharge gap, applied voltage, outer electrode length, two outer electrodes, and gas flow rate. The results showed that CO2 conversion was decreased when CO2 concentration increased. Similarly, the increase of gas flow rate also caused the decrease of CO2 conversion. Whilst the increase of an applied voltage causes the CO2 conversion clearly increased. Similarly, the CO2:Ar ratio of 60%:40% achieved 30% of CO2 conversion. Furthermore, the high percentage of CO2 conversion of 47.2% has been obtained from a 1.3 mm discharge gap with 40 ml/min of gas flow rate.

Tunable work function of molybdenum oxynitride for electron-selective contact in crystalline silicon solar cells

Dopant-free carrier-selective contacts based on metal compounds have attracted considerable attention for high-efficiency crystalline silicon solar cells. In this work, the feasibility of using molybdenum oxynitride (MoOxNy) as an electron-selective contact layer in n-type crystalline silicon (n-Si) solar cells has been demonstrated. With the increase in the N2:Ar ratio during the sputtering process, the work function of a MoOxNy film decreases from 4.57 to 4.26 eV, which is advantageous for the MoOxNy film to be an electron transport layer. An efficiency of 18.0% has been achieved in n-Si based solar cells using a full-area MoOxNy contact for electron extraction, featuring a high fill factor of 84.6%.

CO-PYROLYSIS of agricultural waste and estimation of the applicability of pyrolysis in the integrated technology of biorenewable hydrogen production

For the production of biorenewable hydrogen, the possibility of pyrolysis of agricultural waste, namely cow manure (CM) and stems of weed Amaranthus retroflexus L. (AR), as well as their mixtures in a ratio of 1:1, 2:1 and 4:1, was investigated. Thermogravimetric analysis was carried out at a heating rate of 10 °C/min in the temperature range from 40 °C to 1000 °C. It was shown that the thermal decomposition of agricultural waste in an inert environment is characterized by three main stages, the most significant of which is in the temperature range from 145 to 410 °C, at which the maximum yield of volatile components occurs. Pyrolysis was carried out at a temperature of 550 °C and a heating rate of 10 °C/min. During the pyrolysis of CM and AR mixture, the material balance was on average as follows: 36.95% pyrolysis liquid, 24.99% syngas and 38.06% biochar, and the maximum hydrogen concentration in the pyrolysis gas was 21.17% with CM to AR ratio of 4:1. With this ratio, the hydrogen yield was 12.1% higher than when using a mixture of CM and AR with a 1:1 ratio. An increase in the proportion of AR in the mixture led to the enrichment of the pyrolysis liquid with phenolic compounds. The obtained high content of fixed carbon (47.52%) in biochar is attractive for its use as soil additives. For further research on increasing the yield of gaseous hydrogen from biomass, a scheme of bio-thermochemical processing was proposed, involving a combination of dark fermentation and pyrolysis.

Helium, neon and argon in alkaline basalt-related corundum megacrysts: Implications for their origin and forming process

Corundum megacrysts from Cenozoic alkaline basaltic fields, notably in eastern Asia and Australia, are economically important but poorly understood in their genesis. Here we present new crushing noble gas (He, Ne and Ar) data of alkali basalt-related corundum and some other mineral megacrysts from several localities worldwide to better constrain their ultimate fluid (material) source and forming process. Markedly, the corundum megacrysts have widespread mid ocean ridge basalts (MORB)-like 3He/4He ratios (8 ± 1 RA, where RA is atmospheric 3He/4He ratio of 1.39 × 10−6) in each locality, although lower than MORB 3He/4He ratios also occur in some cases. The latter could be interpreted as the addition of ingrowth 4He but not reflect the initially trapped compositions. The initially MORB-like 3He/4He and high 40Ar/36Ar isotopic ratios, combined with major element and fluid inclusion data, support that the asthenosphere-derived melts/fluids are the primary source for their formation, which is genetically related to the generation of the Cenozoic continental alkaline basalts and mafic megacrysts like clinopyroxene and garnet. Elemental fractionation between helium and argon, enriched in helium compared to the current mantle production value, was observed in most blue-green-yellow (BGY) sapphires, notably for the samples from Changle, eastern China and Ban Huai Sai, Laos. However, the blue sapphires from Wenchang, China do not show such an enrichment. The elevated 4He/40Ar* (40Ar* is radiogenic Ar corrected for atmospheric Ar) ratios are interpreted as a solubility-controlled fractionation during magma degassing. Based on the degree of fractionation, the degassing scheme is most likely to be a single-stage process in closed systems (e.g., in a magma chamber), and the original volatile (assuming pure CO2) content of the parental melts before vesiculation is estimated to be ∼3.5 wt.% in minimum. The degassing process may have caused a sudden Al-saturation of the parental magma and facilitated the crystallization of sapphires by losing alkalis from the magma and decreasing the system's temperature. However, the “degassing” model, so far, has limitations to interpret the Wenchang data. After crystallization of the BGY sapphires at depths of deep to middle crust levels, a new pulse of alkaline basaltic melt carries them to the surface.

Dynamic Stall Characteristics of Pitching Swept Finite-Aspect-Ratio Wings

An experimental investigation regarding the dynamic stall of various swept wing models with pitching motion was performed to analyze the effect of sweep on the dynamic stall. The experiments were performed on a wing with a NACA0012 airfoil section with an aspect ratio of AR = 4. The experimental study was conducted for chord-based Reynolds number Rec =2×105 and freestream Mach number Ma=0.1. First, a ‘particle image velocimetry’ (PIV) experiment was performed on the wing with three sweep angles, Λ=0o, 15o, and 30o, to obtain the flow structure at several wing spans. The results obtained at a reduced frequency showed that a laminar separation bubble forms at the leading edge of the wing during upward motion. As the upward pitching motion continues, a separation burst occurs and shifts towards the wing trailing edge. As the wing starts to pitch downward, the growing dynamic stall vortex (DSV) vortex sheds from the wing’s trailing edge. With the increasing sweep angle of the wing, the stall angle is delayed during the dynamic motion of the wing, and the presence of DSV shifts toward the wingtip. During the second stage, a ‘turbo pressure-sensitive paint’ (PSP) technique was deployed to obtain the phase average of the surface pressure patterns of the DSV at a reduced frequency, k=0.1. The phase average of pressure shows a distinct pressure map for two sweep angles, Λ=0o, 30o, and demonstrates a similar trend to that presented in the published computational studies and the experimental data obtained from the current PIV campaign.

Effect of pressure on the thermo-oxidative behavior of saturates, aromatics, and resins (S-Ar-R) mixtures

To understand the effect of pressure on the interactions between saturates, aromatics, and resins (S-Ar-R) fractions during thermo-oxidation reactions, this study evaluates the oxidation behavior of saturates:resins (S:R), saturates:aromatics (S:Ar), and aromatics:resins (Ar:R) mixtures at 0.084, 3.0 and 6.0 MPa. Oxidation was analyzed by high-pressure thermogravimetric analysis in terms of mass change and rate for mass change. Kinetic analysis was done using a first-order kinetic model discretizing thermal profiles in four regions: oxygen chemisorption (OC), decomposition of chemisorbed oxygen-based compounds (DCO), first combustion (FC), and second combustion (SC). The results demonstrate the role of pressure on the simultaneous oxidation of S:Ar, S:R, and Ar:R mixtures. First, S:Ar thermo-oxidative profiles are described by FC and SC at 0.084 MPa, regardless of the S:Ar ratio. When the oxidation is evaluated at 3.0 and 6.0 MPa, OC and DCO zones are observed, and the amount of oxygen chemisorbed increased as pressure increased. The same trend was observed for S:R and Ar:R systems. Between the S:Ar mixtures, the oxygen chemisorption increased as the amount of aromatics increased too, at 3.0 and 6.0 MPa. The structures formatted at high pressure, present higher reactivity, and therefore, the total consumption of the samples end at lower temperatures. During S:R oxidation, the higher the content of resins, the higher the oxygen chemisorption and the lower the temperature required to decompose the samples. Finally, the mixture between aromatics and resins shows slower kinetic rates than for the other systems. The products from the oxidation of the resins' aliphatic structure react in FC with the aromatics, promoting combustion reactions at higher pressures. The kinetic parameters corroborated the results obtained. For the systems with higher chemisorption, the effective activation energy values were higher, therefore the DCO values. In comparison, the pre-exponential factor showed opposite results, given slower reaction kinetics in these stages.

Controllable Wetting Modification of Polypropylene Fibrous Mats

In this study, polypropylene (PP) fibrous mats are modified by plasma treatment, following by chemical grafting. Initially, the as-prepared PP fibrous mats are treated by plasma at different oxygen (O2) and argon (Ar) ratios. Then, the PP fibrous mats are modified by grafting dopamine onto polar groups for in situ polymerizations, resulting in a polydopamine (PDA) coating on the substrate's surface. Time-sensitive wettability is thereby converted into permanent wettability in PP fibers. The morphology, chemical performance, and relative wettability of the modified PP fibers are then characterized. The experimental results show, using an O2/Ar ratio of 3:7 during plasma treatment, that the water contact angle was decreased from 114.2° to 0°, and the maximum grafting degree was 0.79%.

A numerical study of the solidification process of a retracting fluid filament

In this study, the retraction and solidification of a fluid filament are studied by a front-tracking method/finite difference scheme. The interface between two phases is handled by connected points (Lagrangian grid), which move on a fixed grid domain (Eulerian grid). The Navier-Stokes and energy equations are solved to simulate the problem. Initially, the fluid filament has a shape as half of a cylindrical capsule contact with a cold flat surface. We consider the effect of the aspect ratio (Ar) on the solidification of the fluid filament. It is found that an increase in the aspect ratio (Ar) in the range of 2 – 14 causes the retraction length to increase. The rate of the solidification of a fluid filament decreases when the Ar ratio increases. The solidification time, the solidification height and the tip angle of the fluid filament under the influence of the aspect ratio are also considered. After complete solidification, a small protrusion on the top of the solidified fluid filament is found.

Moist Air Flow Analysis in an Open Enclosure. Part A: Parametric Study

Heat and mass transfer in many systems are widely accomplished applying natural convection process due to their low cost, reliability, and easy support. Typical applications include different mechanisms in various fields such as (solar energy, solar distiller, stream cooling, etc…). Numerical results of turbulent natural convection and mass transfer in an open enclosure for different aspect ratios (AR = 0.5, 1, and 2) with a humid-air are carried out. Mass fraction and local Nusselt number were proposed to investigate the heat and mass transfer. A heat flux boundary conditions were subjected to the lateral walls and the bottom one make as an adiabatic wall, while the top area was proposed as a free surface. Effect of Rayleigh numbers (106≤????????≤108) on natural convection and mass flow behavior are analyzed. The governing equations are solved using CFD Fluent code based on the SIMPLE algorithm. The results showed that the cavity with an aspect ratio of AR = 2 has a significant enhancement to raise the rates of both heat and mass transfer. When the Rayleigh number increases, maximum heat transfer rates were observed due to the fluid flow becomes more vigorous. However, mass transfer improves as the Rayleigh number decreases.

Turbulence Characteristics of the Flexible Circular Cylinder Agitator

A flexible protruding surface was employed as the flow disturbance to promote turbulence at the area of interest. An ultrasonic velocity profiler, UVP technique, was used to study the mean and fluctuating flow properties in the near wake of the rigid and flexible protruding surface in a water tunnel. The polymer based, ethylene-vinyl acetate (EVA) with an aspect ratio of AR = 10, 12, 14, 16 was used as the flexible circular cylinder, and submerged in a flow at Re = 4000, 6000 and 8000. The motion of the cylinder altered the fluid flow significantly. As a means to quantify turbulence, the wakes regions and production terms were analyzed. In general, the flexible cylinders show better capability in augmenting the turbulence than the rigid cylinder. The results show that the turbulence production term generated by the flexible cylinder is higher than that of rigid cylinder. The localized maximum shear production values have increased significantly from 131%, 203% and 94% against their rigid counterparts of AR = 16 at the Re = 4000, 6000 and 8000, respectively. The performance of turbulence enhancement depends heavily on the motion of the cylinder. The findings suggest that the turbulence enhancement was due to the oscillation of the flexible cylinder. The results have concluded that the flexible cylinder is a better turbulence generator than the rigid cylinder, thus improving the mixing of fluid through augmented turbulent flow.

Circulating Adiponectin and Resistin Levels Are Associated with Adiposity Indices and Physical Fitness in Healthy Adult Males

BackgroundThe aim of this study was to assess the correlation of physical fitness scores (PFS) with serum adiponectin, resistin, and adiponectin/resistin ratio (AR ratio) in relation to body adiposity indices in healthy adult males.Material/MethodsThis cross-sectional study was conducted at the Clinical Physiology Unit, Physiology Department, King Saud University Medical City, King Saud University, Riyadh, from March 2017 to April 2018. We included 125 healthy adult males. Serum samples were obtained after overnight fasting. Analysis was performed for fasting blood glucose (FBG), glycosylated hemoglobin (HbA1c), basal insulin, lipid profile, resistin, and adiponectin. Bioimpedance analysis (BIA) was used to assess body composition. Based on ideal body composition, PFS were computed as previously published for all subjects and compared with serum markers.ResultsThere was a positive correlation of adiponectin with PFS (r=.218, p=0.015) and an inverse correlation with obesity degree (OD), OD (r=−.239, p=0.001), body mass index (BMI) (r=−.244, p=0.001), and waist/hip ratio (WHR) WHR (r=−.296, p=0.001). Moreover, it was correlated negatively with basal insulin (r=−.211, p=0.009) and homeostatic insulin resistance model (HOMA-IR) HOMA-IR (r=−.221, p=0.013). Resistin was correlated negatively with PFS (r=−.203, p=0.023), while its correlation with OD, BMI, WHR, and HOMA-IR was not significant. AR ratio was positively correlated with PFS (r=.286, p=0.001) and negatively with OD (r=−.210, p=0.019), BMI (r=−.222, p=0.013), WHR (r=−.308, p=0.001) and basal insulin (r=−.237, p=0.008). In linear regression analysis, the relationship of PFS was significant with adiponectin (r=.218, p=0.015), resistin (r=−.203, p=0.023) and AR ratio (r=.286, p=0.001). ROC curve analysis showed that individually the values of adiponectin and resistin were not significantly correlated with PFS, but they were significant with the combined AR ratio with AUC 64.6% (p=0.029).ConclusionsSerum adiponectin was positively correlated and resistin was negatively correlated with physical fitness scores based on healthy body composition with low proportion of body adiposity and a higher proportion of fat-free mass. However, the combined effect of adiponectin/resistin ratio is an even better predictor of physical fitness. Moreover, the adiponectin/resistin ratio is even more highly associated with physical fitness than adiponectin or resistin alone.

Experimental study on the pressure distribution of a low aspect-ratio circular cylinder and interference effects of a square cylinder in downburst flows

Wind loads on a surface-mounted finite-height circular cylinder are strongly influenced by the flow field structure. Based on the stationary and moving downburst flows simulated by an impinging jet device, this paper studies the wind pressure distribution in a circular cylinder with a low aspect ratio of AR = 2 at different radial positions and discusses the interference effects of other cylinders. The results indicate that the Reynolds number has a significant effect on the mean wind pressure coefficient on the crosswind side. The maximum absolute value of the mean coefficients on the leeward and crosswind sides appears at r/Djet = 1.0. In general, the interference effect of the square cylinder closely spaced on the fluctuating coefficients of each side is the largest when it is in the upstream position in tandem. The pressure distribution on the crosswind side is more easily affected by the interference cylinder. Under the action of a moving downburst, the instantaneous pressure coefficients on all sides of the cylinder have both positive and negative peaks, and the maximum overshooting variation is close to three. The overshooting effect lasts in a shorter time and has a greater impact on the structure when the downburst moving speed is faster.

Efficacy and Safety of Tripterygium Glycoside in the Treatment of Diabetic Nephropathy: A Systematic Review and Meta-Analysis Based on the Duration of Medication.

AimThe aim of this study was to assess the clinical efficacy and safety of Tripterygium-derived glycosides (TG) after 3-month and 6-month of treatments of diabetic nephropathy (DN) and to resolve the conflict between medicine guidance and clinical practice for TG application.MethodsWe conducted a systematic review and meta-analysis of randomized controlled trials involving TG application in treating DN. We extensively searched PubMed, Cochrane Library, CNKI, VIP, Wan-Fang, CBM, Chinese Clinical Trial Registry, and WHO International Clinical Trial Registration Platform till November 2020, along with grey literature for diabetes and all other relevant publications to gather eligible studies. Based on the preset inclusion and exclusion criteria, document screening, quality assessment of methodology, and data extraction was conducted by two researchers independently. The methodological quality was assessed by the Cochrane risk test from the Cochrane Handbook 5.2, and then analyses were performed by Review Manager 5.3 (Rev Man 5.3). The quality of output evidence was classified by GRADE.ResultsThirty-one eligible studies (2764 patients) were included for this meta-analysis. Our study results showed a comparable significant decrease in the 24 h-UTP and blood creatinine levels in DN patients from both 3-month and 6-month TG treatment groups, compared with the routine symptomatic treatment alone. To the contrary of the findings from the included studies, our results showed that the occurrence of serious adverse reaction events was significantly higher in the TG treated group with 6 months of treatment duration compared to that of 3 months of the treatment course. However, the total AR ratio was slightly varied while increasing the percent of severe adverse events. GRADE assessment indicated that the quality of evidence investigating TG-induced adverse reactions was moderate and that for 24 h-UTP and blood creatinine indicators were considerably low.ConclusionCombinatorial treatment regimen including TG can significantly decrease the pathological indicators for DN progression, while it can also simultaneously predispose the patient to a higher risk for developing severe adverse events, as the medicine guidance indicates. Notably, even in 3-month of course duration smaller percent of severe adverse events can get to a fatal high percent and is likely to increase proportionally as the TG treatment continues. This suggests that TG-mediated DN treatment duration should be optimized to even less than 3 continuous months to avoid adverse event onset-associated further medical complications in DN patients. In clinical practice, serious attention should be paid to these severe side-effects even in a course normally considered safe, and importantly more high-quality studies are urgently warranted to obtain detailed insights into the balance between the efficacy and safety profiles of TG application in treating DN.

Minimizing film residual stress with in situ OES big data using principal component analysis of deposited AlN films by pulsed DC reactive sputtering

In this study, aluminum nitride (AlN) thin films were deposited on Si (100) and investigated on the minimum film residual stress with varying two critical deposition conditions in N2 gas flow and power. The pulsed DC reactive sputtering of aluminum targets was carried out in gas ratio of nitrogen (N2) and argon (Ar) plasma with N2:Ar ratios from 15:15 to 60:15 and power from 400 to 1000 W. According to the large-scale data of in situ optical emission spectroscopy (OES) study in connection with film microstructure information by analyzing X-ray diffraction (XRD) patterns, scanning electron microscope (SEM) micrographs, transmission electron microscope (TEM) analyses, Fourier-transform infrared spectroscopy (FTIR) spectra, and alpha-step profilers, the deposited film stress states can be highly affected by the critical processing parameters of N2 flow rate and power. In addition, the proposed value of residual stress (VRS) can be calculated by PC1-DEV (the standard deviation in the first principal component direction) method for accurate prediction of the stress states of deposited films, i.e., compressive stress or tensile stress, which will provide valuable information on residual stress characterization as the in situ monitoring tool for the AlN thin film deposition process. In summary, a methodology based on large data of OES by which principal component analysis (PCA) was utilized to reduce its dimension can be used to determine residual stress characterization from a simple measurement in situ plasma monitoring tool is suggested.