A Hybrid Probabilistic Model for Evaluating and Simulating Human Error in Industrial Emergency Conditions (HEIE)

Over the years, many techniques have been developed for human reliability analysis (HRA). The main weakness of traditional HRA approaches is the use of a simple classification scheme without a link to a model of cognition in terms of mental processes. The present work is an attempt in this direction through a particular hybrid probabilistic model. The human error in industrial emergency model aims to develop an integrated methodological approach useful in critical infrastructures during an emergency condition. The proposed method, starting from the integration of existing techniques, develops a very flexible tool, able to take into account the main external and internal factors responsible of human error in emergency conditions. The model is able to estimate the evolution of human behavior and error following the evolution of the emergency scenario. The final result is a simulation model that calculates the contextualized human error probability, through which it is possible to estimate a realistic and detailed scenario of the conditions during the emergency management.     

Electrosprayed poly(vinyl alcohol) particles: preparation and evaluation of their drug release profile

Encapsulation of bioactive molecules within polymeric particles is a challenge because of several limitations, including low drug‐loading efficiency, unwanted release profile, polydispersity and batch‐to‐batch variation in reproducibility, along with the limitations of scaling up the process. It is essential to control the morphology of pure polymer particles in the first instance, in order to obtain the desired release profile of drugs from the particles during a later stage. Here we report the preparation of electrosprayed particles from a water‐soluble US Food and Drug Administration‐recognized polymer, namely poly(vinyl alcohol) (PVA), as an approach towards a short‐term drug delivery vehicle. Through electrospraying and varying the solvent ratios, three different sizes of particles were prepared, with sizes ranging from 500 to 2000 nm. Insulin was chosen as a model bioactive molecule, and the release profile of the drug was studied after its incorporation in the PVA particles. Fractional release plots obtained showed short‐term release of insulin within the first 60 min. Release curves were analyzed according to the Ritger–Peppas model, suggesting Fickian diffusion as the predominant insulin release mechanism from the PVA particles. This work suggests electrosprayed PVA particles as an innovative drug delivery system for short‐term administration of drugs. © 2015 Society of Chemical Industry     

The occurrence and identification of alpha-thalassemia-2 among hemoglobin S heterozygotes

The in-vitro synthesis of hemoglobin (Hb) chains was studied among 60 Hb S heterozygotes (AS) having different quantities of Hb S, including five with an associated alpha-chain heterozygosity (ASAG). Hematologic values and hemoglobin composition were studied in these cases and in 15 other ASAG heterozygotes. The percentages of Hb S (which fell between 27% and 42%) and the mean corpuscular volume values correlated directly with the alpha/non-alpha values, confirming previous suggestions (Huisman, Hemoglobin 1:349, 1977) that the concomitant occurrence of an alpha-thalassemia-2 heterozygosity (alpha alpha(0)/alpha alpha; beta/beta(S)) or homozygosity (alpha(0) alpha/alpha(0) alpha; beta/beta(S)) resulted in intermediate or lower levels of Hb S compared with Hb S heterozygotes having four active alpha-chain genes (alpha alpha/alpha alpha; beta/beta(S)). Among ASAG heterozygotes, the occurrence of low (about 25%), intermediate (about 33%), or high (about 45%) proportions of an alpha-chain variant resulting from a variability in the number of active alpha-chain genes due to alpha-thal-2 coincided with high (39%), intermediate (34%), or low (28%) levels of Hb S, respectively. However, the overlap of biosynthetic data between Hb S heterozygotes with four, three, or two active alpha-chain genes prevents a reliable diagnosis in individual cases.     

A new SPICE subcircuit model of power p-i-n diode

A new modeling approach for the power p-i-n diode is proposed. The base region is represented with a two-port network, obtained by solving the ambipolar diffusion equation with the Laplace transform method, and by approximating the resulting transcendental functions in the s-domain with rational approximations. Two different networks have been obtained. The first one, based on Taylor-series approximation is shown to be a generalization of a two-port model already proposed in the literature for the nonquasi-static modeling of bipolar transistors. The second network representation is based on Pade' approximation and is shown to be more accurate than the Taylor-series approach, The obtained RLC networks are easily implemented in a PSPICE subcircuit which also takes into account the emitter recombination effects and the dynamic of the space-charge voltage build-up. Good agreement has been obtained by comparing the results of the proposed model with numerical device simulations     

Determination of lipase specificity

Specificity of lipases is controlled by the molecular properties of the enzyme, structure of the substrate and factors affecting binding of the enzyme to the substrate. Types of specificity are as follows. I. Substrate: (a) different rates of lipolysis of TG, DG, and MG by the same enzyme; (b) separate enzymes from the same source for TG, DG and MG. II. Positional: (a) primary esters; (b) secondary esters; and (c) all three esters or nonspecific hydrolysis. III. Fatty acid, preference for similar fatty acids. IV. Stereospecificity: faster hydrolysis of one primarysn ester as compared to the other. V. Combinations of I–IV. Lipases with these specificities are: Ia, pancreatic; Ib, postheparin plasma. IIa, pancreatic; IIb,Geotrichum candidum, for fatty acids withcis-9-unsaturation, and IIc,Candida cylindracea. III,G. candidum for unsaturates. IV.sn-1, postheparin plasma andsn-3 human and rat lingual lipases. V. Rat lingual lipase. Methods for determination involve digestion of natural fats of known structure and synthetic acylglycerols followed by analysis of the lipolysis products. All of the types of specificity have been detected with use of synthetic acylglycerols. Detection of stereospecificity requires enantiomeric acylglycerols which are difficult to synthesize, so other methods have been developed. These involve the generation of 1,2-(2,3) DG and resolution of the enantiomers. Trioleoylglycerol or racemic TG can be used as substrates. If the lipase is stereospecific, then either thesn-1,2- or 2,3-enantiomer will predominate. The relative amounts of the enantiomers can be determined by measurement of specific rotation, and nuclear magnetic resonance spectra. The DG can also be separated by conversion to phospholipids and hydrolysis with phospholipases A-2 or C. Applications of these procedures are discussed and data on the specificity of various lipases presented. Scientific Contribution No. 988, Storrs Agricultural Experiment Station, University of Connecticut, Storrs, CT 06268. Trioleoylglycerol is 18∶1−18∶1−18∶1, etc. 1,2-dioleoyl-3-palmitoyl-sn-glycerol issn-18∶1−18∶1−16∶0, with thesn-1 ester to the left. If the TG is racemic,rac is omitted.     

Fatty acid and positional selectivities of gastric lipase from premature human infants:in vitro studies

Gastric lipase activity in aspirates from premature human infants was tested for fatty acid and positional selectivity using racemic diacid triacylglycerols (TG) as substrates. The resulting free fatty acids and monoacylglycerols (MG) were recovered and analyzed. Octanoic acid (8∶0) and decanoic acid (10∶0) were hydrolyzed with a preference of 61.5∶1 and 2.4∶1 compared to palmitic acid (16∶0) fromrac-16∶0–8∶8∶0 andrac-16∶0–10∶0–10∶0, respectively. The ratio of lauric acid (12∶0) to oleic acid (18∶1) hydrolyzed fromrac-18∶1–12∶0 was 13∶1. Myristic acid (14∶0), 18∶1 and linoleic acid (18∶2) were released at similar rates. These data and the composition of the MG suggest that,in vitro, the lipase is selective for shorter chain fatty acids and for fatty acids on the primary positions of the TG backbone.