A meta-analytic review of the relationship between absence and turnover.

A meta-analysis that combined 33 correlations from 17 studies found a corrected average correlation of .330 between absence and turnover. The type of absence measure did not moderate the covariation between absence and turnover, but industry type and study duration did act as moderators. The results are discussed in the context of the "withdrawal" approach to understanding employee behaviors. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Microstructure and mechanical properties of mechanically alloyed and spark plasma sintered amorphous–nanocrystalline Al65Cu20Ti15 intermetallic matrix composite reinforced with TiO2 nanoparticles

Multiphase Al₆₅Cu₂₀Ti₁₅ intermetallic alloy matrix composite, dispersed with 10 wt.% of TiO₂ nanoparticles, has been processed by mechanical alloying, followed by spark plasma sintering under pressure in the temperature range of 623–873 K. Differential scanning calorimetry and X-ray diffraction suggest that equilibrium crystalline phases evolve from the amorphous or intermediate crystalline phases. Transmission electron microscopy shows that the composite sintered at 873 K has partially amorphous microstructure, with dispersion of equilibrium, crystalline, intermetallic precipitates of Al₅CuTi₂, Al₃Ti, and Al₂Cu of 25–50 nm size, besides the TiO₂. The composite sintered at 873 K exhibits little porosity, hardness of 5.6 GPa, indentation fracture toughness in the range of 3.1–4.2 MPa√m, and compressive strength of 1.1 GPa. Indentation crack deflection by TiO₂ particle aggregates causes increase in fracture resistance with crack length, and suggests R-curve type behaviour. The study provides guidelines for processing high strength amorphous–nanocrystalline intermetallic composites based on the Al–Cu–Ti ternary system.     

Novel PDMS‐based membranes: Sodium chloride and glucose permeability

Permeation of sodium chloride and glucose through polydimethylsiloxane‐poly(N‐isopropylacrylamide) (PDMS‐PNIPAAm) interpenetrating polymer networks (IPNs) of two different microstructures was investigated. We have successfully developed small‐molecule permeable IPNs, by modifying PDMS film structure. A group of PDMS films was prepared using conventional solvent casting (SC) method and another group produced by introducing oil, followed by SC and leaching the oil out (SCOL method). Scanning electron microscopy (SEM) and attenuated total reflection fourier transformer infrared (ATR‐FTIR) spectroscopy results confirmed the presence of PNIPAAm in the SC and SCOL IPNs. Results obtained from spectra of differential scanning calorimetry (DSC) showed that these IPNs had a phase transition temperature at about 32°C. Permeation measurements showed that the presence of PNIPAAm as the second phase in the IPN, improved the permeability of PDMS film. According to the results, maximum permeation coefficient was related to SCOL IPN containing 15.8% ± 0.3%PNIPAAm, at 23°C (5.98 × 10^?7 ± 7.93 × 10^?9 cm²/s for sodium chloride and 3.6 × 10^?7 ± 7 × 10^?9 cm²/s for glucose). These results suggested that these PDMS‐PNIPAAm IPNs with sodium chloride and glucose permeability may be further developed as ophthalmic biomaterials or corneal replacements. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Inferential estimation of molecular weights of polybutadiene rubber by neural networks

Molecular weight distribution, which is characterized by its averages like number average (Mn) and weight average (Mw), is one of the important properties of polybutadiene rubber (PBR), and it is difficult to measure. The objective of this work is to develop models to predict Mn and Mw from readily available process variables. Neural networks that are capable of mapping highly complex and non‐linear dependencies have been adapted to develop models for the Mn and Mw of PBR. The molecular weight distribution and its averages of PBR samples collected over a wide range of operating conditions were measured by the conventional Gel Permeable Chromatograph (GPC) method. Neural networks were trained with relevant data to predict Mn and Mw from process variables. The trained networks were found to generalize well when tested with new data. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 1611–1618, 2005     

Experimental study of paddy drying in a vortex chamber

The intensification of interfacial mass, heat, and momentum transfer makes vortex chambers potentially interesting for the efficient drying of paddy, allowing shorter drying times and/or more compact equipment. The presence of a shell introduces particular challenges. Intraparticle diffusion limitations are strong and may reduce the advantage from intensified interfacial mass and heat transfer and the efficiency of air usage. Furthermore, high shear and normal stresses in the fast rotating particle bed may cause damage to the paddy shell, posing problems for transport and storage. With these specific aspects in mind, the use of vortex chambers for paddy drying is experimentally evaluated.     

Growth kinetics and lipid production using Chlorella vulgaris in a circulating loop photobioreactor

BACKGROUND: Compared with agriculture, microalgae culture promises to be a novel way of producing lipids for both food consumption and transportation fuel (biodiesel) purposes while using a minimal amount of land area. A circulating loop photobioreactor has been used to study the growth kinetics and lipid yield of Chlorella vulgaris growing on carbon dioxide as the sole source of carbon. RESULTS: Because of high photosynthetic active radiation (PAR) fluxes, C. vulgaris was observed to grow in exponential mode. The highest growth rate achieved was 0.049 h^?1 at the optimum growth conditions of 71.8 mW L^?1 PAR density, 10% CO₂ (v/v) in air and with an applied 8 h dark phase. The microalgae was observed to grow in a Monod fashion with a PAR density saturation coefficient of 2.8 mW L^?1. Light intensity showed the potential to significantly increase lipid yield, which reached a maximum of 30% (by mass) of cell dry weight. CONCLUSION: The circulating loop photobioreactor is a low‐cost bioreactor technology capable of culturing photosynthetic microalgae at high PAR densities and with uniform mixing and lighting. C. vulgaris is able to grow exponentially in this bioreactor and produce lipids at concentrations up to 30% by cell dry weight. Copyright © 2011 Society of Chemical Industry     

Investigation of Nucleation Mechanism and Tapering Observed in ZnO Nanowire Growth by Carbothermal Reduction Technique

ZnO nanowire nucleation mechanism and initial stages of nanowire growth using the carbothermal reduction technique are studied confirming the involvement of the catalyst at the tip in the growth process. Role of the Au catalyst is further confirmed when the tapering observed in the nanowires can be explained by the change in the shape of the catalyst causing a variation of the contact area at the liquid–solid interface of the nanowires. The rate of decrease in nanowire diameter with length on the average is found to be 0.36 nm/s and this rate is larger near the base. Variation in the ZnO nanowire diameter with length is further explained on the basis of the rate at which Zn atoms are supplied as well as the droplet stability at the high flow rates and temperature. Further, saw-tooth faceting is noticed in tapered nanowires, and the formation is analyzed crystallographically.     

Scientific basis for establishing country greenhouse gas estimates for rice-based agriculture: An Indian case study

A comprehensive scientific assessment of CH₄ budget estimation for Indian rice paddies, based on a decade of measurements in India, is presented. Indian paddy cultivation areas contain soils that have low to medium levels of soil organic carbon. The average seasonally integrated CH₄ flux (E _sif) values calculated from these measurements were 15.3 ± 2.6 g m^–2 for continuously flooded (CF), 6.9 ± 4.3 g m^–2 for intermittently flooded (IF) single aeration (SA) and 2.2 ± 1.5 g m^–2 for IF multiple aeration (MA) rice ecosystems. For CF and IF (MA) rice ecosystems having high soil organic carbon, without organic amendments, the CH₄ flux (E _sif) may be increased by 1.7 times relative to low soil organic carbon, whereas it may enhance by 5.3 for CF if amended organically. Organic amendment and high soil organic carbon paddy areas do not alter the methane budget estimates for India (3.6±1.4 TgY^–1) much, due to their small paddy harvested area. Methane estimated using average emission factors (E _sif) for all paddy water regimes, which include harvested areas having soils with high organic carbon and organic amendments, may give a budget of 5 TgY^–1 for India.     

Headspace Volatile Oxylipins of Eastern Himalayan Moss Cyathophorella adiantum Extracted by Sample Enrichment Probe

Cyathophorella adiantum (Griff.) M. Fleisch. (Division-Bryophyta, Family-Daltoniaceae), an Eastern Himalayan moss was studied for the first time to identify the volatiles derived from cellular and membrane bound fatty acids. A high capacity sample enrichment probe (SEP) was used for extraction of headspace volatile (HSV) molecules followed by GC–MS analysis. Different short-chain oxylipins like alkenes, alkanes, saturated and unsaturated alcohols, saturated and unsaturated aldehydes, ketones were identified along with free and esterified fatty acids, cyclo compounds and some by-products of secondary metabolites. Fatty acid analysis of neutral lipids (NL) and phospholipids (PL) of this plant exhibits the predominance of C16 and C18 fatty acids. It also reveals some interesting information that might indicate the possible fatty acid precursors for volatile generation and their sources in this plant.