Numerical Investigation of Convective Heat Transfer in Unsteady Laminar Flow Over a Square Cylinder in a Channel

Unsteady laminar flow past a heated square cylinder mounted inside a plane channel was investigated numerically. The blockage ratio was chosen as 1/8 and the Reynolds number based on the mean flow velocity and chord length of the square cylinder was selected as less than 200, for which the two-dimensional behavior of the flow is assured. The time-averaged Nusselt number as well as some integral parameters such as drag coefficient, recirculation length, and Strouhal number were obtained and compared with literature. Results show a nearly linear increase in recirculation length and decrease in drag coefficient with increasing Reynolds number for the steady flow regime. There is an increase in the total Nusselt number and drag coefficient with a Reynolds number for unsteady flow regime, where vortex shedding is observed from the cylinder. A correlation was obtained for the variation of the total Nusselt number with the Reynolds number.     

The strength of particulate polymer composite: A new insight on crystallinity and structural morphology

We have demonstrated the significant impact of high density polyethylene (HDPE) crystallinity and structural morphology on the tensile strength of 60/40 NR/HDPE polymer blend composites. Introducing nanoscale Boron Carbide (B4C-type compounds) fillers noticeably changed the crystallinity and morphology of HDPE, leading to the formation of fine spherulites. Conversely, microscale fillers mainly impacted the crystallinity while preserving a coarse architecture. Although both composites experienced a reduction in crystallinity, the nanocomposites outperformed microcomposites and even the pristine polymer blend in terms of strength, implying the effect of a fine structure. The nanocomposite with a filler loading of 2 wt% exhibited the highest strength. This investigation provides novel insights into the interplay between crystallinity, HDPE structure, and the size of fillers, which heavily influence the strength of polymer blend composites.     

Effect of Impact Milling and Ball Milling on Microstructure of Lead Titanate Powders Synthesized by Solid-State Reaction

Single phase lead titanate （PbTiO3） was prepared by solid-state route using lead （1I） oxide （PbO） and titanium dioxide （TiO2） as precursors. The effects of using impact mill （IM） and ball mill （BM） in solid state reaction have been observed. X-ray diffraction （XRD） pattern was recorded at room temperature and analyzed by employing Rietveld method. X-ray diffraction （XRD） pattern shows that the PbTiO3 particles are tetragonal with tetragonality （c/a） ratio ranging from 1.058 to 1.063 and average crystallite size from 40.8 to 64.2 nm. It is found that the impact mill （IM） can be used to produce pure tetragonal perovskite with a lower tetragonality and average crystallite size.     

Short communication: Blood metabolites,body reserves,and feed efficiency of high-producing dairy cows that varied in ruminal pH when fed a high-concentrate diet

Recent studies report considerable variation in ruminal pH for lactating dairy cows even when fed the same diet. We hypothesized that blood metabolites would be indicators of low ruminal pH, and hence could be used as predictors to help manage this variability. The objective of the study was to determine whether blood metabolite concentrations, body reserves, and feed efficiency were associated with ruminal pH in high-producing dairy cows fed a high-concentrate diet. Seventy-eight individually fed lactating dairy cows (days in milk = 103 ± 27; body weight = 638 ± 77 kg at the start; mean ± SD) were fed a diet consisting of 35% forage and 65% concentrate (dry matter basis). Cows were adapted for 14 d and then were sampled for 10 d. Ruminal pH was measured by rumenocentesis for all cows at the end of the study 4 h after feeding, and reticular pH was measured on a subsample of 14 cows via indwelling sensors for 5 consecutive days. Cows were classified according to rumenocentesis pH as high (pH ≥ 6.0; n = 26), medium (5.8 ≤ pH < 6; n = 21), and low (pH < 5.8; n = 31). Cows were also classified according to reticular pH as high if pH <5.8 persisted <330 min/d (an average of 78 min/d; n = 5) or low if duration of pH <5.8 was ≥330 min/d (an average of 920 min/d; n = 9). The classification based on rumenocentesis pH revealed that serum activity of aspartate aminotransferase (AST) was greater in cows with low ruminal pH (70.7 U/L) than cows with high (56.6 U/L) and medium (59.9 U/L) ruminal pH. Also, the blood urea nitrogen concentration was greater in cows with low ruminal pH (13.6 mg/dL) than cows with medium (12.2 mg/dL) and high (12.5 mg/dL) ruminal pH. Blood albumin concentration was greater for cows with low ruminal pH than for cows with medium and high ruminal pH. The classification based on reticular pH also resulted in a trend of greater AST activity and greater blood urea nitrogen concentration in the blood of cows with low pH. Regression analysis showed high serum concentration of AST was associated with high valerate concentration in ruminal fluid (R² = 0.14), low rumenocentesis pH (R² = 0.10), and low milk fat percentage (R² = 0.06). Glucose, triglyceride, cholesterol, globulin, alkaline phosphates, and serum amyloid A did not differ among the different ruminal pH classes. Low pH cows (reticular and ruminal) had less backfat thickness measured via ultrasound, and cows with low ruminal pH tended to have greater milk:feed ratio. Results indicated that cows that differ in ruminal pH also had different concentrations of blood metabolites and backfat thickness, and AST activity in blood may be a plausible indicator of ruminal pH in dairy cows. Further studies on the applicability of AST in blood as a biomarker for detecting low ruminal pH in dairy cows are warranted.     

Control strategies against grey mould (Botrytis cinerea Pers.: Fr) and corresponding fungicide residues in grapes and wines

This study examines the most effective anti-Botrytis strategies leading to possible lower pesticides residues in wine. To provide wine growers with a number of high-quality solutions for protection against Botrytis for their vineyards while minimizing pesticide residues in the final product, various treatment approaches were tested. A total of 10 strategies with different specific fungicide treatments for controlling Botrytis cinerea were applied to grapes at different growing stages: flowering, bunch closure and colour change. The type of vine chosen was Gamay, as it is very sensitive to Botrytis cinerea. In each experimental plot, disease incidence and severity were assessed at harvest. In addition, pesticide residue analysis was carried out on grapes, musts and wines to monitor residue levels in each treatment and to follow changes at each stage of the wine-making process. A correlation was established between the efficiency of anti-Botrytis fungicide treatment and pesticide residues in wine. Several strategies using various fungicides showed good results in terms of treatment efficiency while minimizing pesticide residues in wine, thus providing interesting alternatives to limit the development of fungal resistance.     

Use of artificial neural networks to determine parameters controlling the nanofibers diameter in electrospinning of nylon‐6,6

This study aimed to find out the primary factors influencing the diameter of electrospun nanofibers of nylon‐6,6 using artificial neural networks (ANNs). Four variables, namely, polymer concentration, working distance, injection rate, and applied voltage were considered as input parameters and the nanofibers diameter measured by scanning electron microscopy was taken as the output. The data were modeled and validated against a set of unseen data. The generated model was used to study the interactions occurring between the input variables and their effect on the diameter. Results show that the injection rate and the polymer concentration are major factors affecting the nanofibers diameter with inverse and direct relations with the diameter, respectively, while the working distance and the applied voltage have direct but minor effects on nanofibers diameter. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci 124:1589–1597, 2011     

Synthesis of Keto-RDX and its Characterizations Calculation（英）

Keto-RDX was obtained by one-step method with a certain amount of RDX as by-product. The effects of various parameters on high yield were studied. A simple analytical method was also introduced to determine simultaneously Keto-RDX/RDX mole ratio. Some important theoretical characterizations of Keto-RDX such as detonation performance at maximum nominal density and shock sensitivity were determined by new methods and compared with RDX.     

Predicting thermal degradation kinetics of nylon6/feather keratin blends using artificial intelligence techniques

A multi-structured architecture of artificial intelligence techniques including artificial neural network (ANN), adaptive-neuro-fuzzy-interference system (ANFIS) and radial basis function (RBF) were developed to predict thermal degradation kinetics (TDK) of nylon6 (NY6)/feather keratin (FK) blend films. By simultaneous implementation of back-propagation ANN and feed-forward ANFIS modeling on the experimental data obtained from thermogravimetric analysis (TGA) method, thermal degradation behavior of various compositions of NY6/FK blends was successfully predicted with minimum mean square errors (MSE). RBF networks were then trained on the TGA data at one heating rate for predicting analogs information at different heating rates, providing sufficient feed for TDK modeling. According to the comparison made between experimental and predicted kinetic parameters of thermal degradation process calculated from Friedman and Kissinger methods, the proposed prediction effort could effectively contribute to the estimation of precise activation energy (E_a) and reaction order (n) values with least amount of experimental work and most accuracy.     

Microfluidic Synthesis of Ultrasmall Chitosan/Graphene Quantum Dots Particles for Intranasal Delivery in Alzheimer's Disease Treatment

Nanoparticles (NPs) based therapies for Alzheimer's disease (AD) attract interest due to their ability to pass across or bypass the blood-brain barrier. Chitosan (CS) NPs or graphene quantum dots (GQDs) are promising drug carriers with excellent physicochemical and electrical properties. The current study proposes the combination of CS and GQDs in ultrasmall NP form not as drug carriers but as theranostic agents for AD. The microfluidic-based synthesis of the CS/GQD NPs with optimized characteristics makes them ideal for transcellular transfer and brain targeting after intranasal (IN) delivery. The NPs have the ability to enter the cytoplasm of C6 glioma cells in vitro and show dose and time-dependent effects on the viability of the cells. IN administration of the NPs to streptozotocin (STZ) induced AD-like models lead to a significant number of entrances of the treated rats to the target arm in the radial arm water maze (RAWM) test. It shows the positive effect of the NPs on the memory recovery of the treated rats. The NPs are detectable in the brain via in vivo bioimaging due to GQDs as diagnostic markers. The noncytotoxic NPs localize in the myelinated axons of hippocampal neurons. They do not affect the clearance of amyloid β (Aβ) plaques at intercellular space. Moreover, they showed no positive impact on the enhancement of MAP2 and NeuN expression as markers of neural regeneration. The memory improvement in treated AD rats may be due to neuroprotection via the anti-inflammation effect and regulation of the brain tissue microenvironment that needs to be studied.     

A comparative study for current transformer dimensioning in overcurrent relay

Dimensioning a current transformer (CT) is one of the most important tasks during the substation planning process. The installation of a correctly specified CT will ensure the integrity of the protection scheme. However, some parameters required for dimensioning a CT can be obtained only after the CT is installed in the substation. Because of the conflicting requirements, utility companies commonly adopt a simplified approach in compensating for the missing parameters. Two other methods for dimensioning CT under the given constraint during the planning stage have also been proposed by several authors. In view of the availability of the three methods of approximating CT specifications, this paper will conduct a comparative study to evaluate their accuracies. The approximated specifications of the CT during the planning stage are compared against those measured from a practical substation. Based on the findings from the comparative studies, the most reliable approach for CT dimensioning during the planning stage is proposed. © 2016 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.