Increased thermal tolerance in Cronobacter sakazakii strains in reconstituted milk powder due to cross protection by physiological stresses

Cronobacter sakazakii (C. sakazakii) is an opportunistic, neonatal, and food borne pathogen primarily associated with the contamination of powdered infant formula (PIF). The pathogen is reported to overcome the food safety barriers such as increased acidity, heat treatment, and so on. This study evaluates the thermal tolerance of C. sakazakii strains independently at 52, 55, and 58°C in reconstituted PIF after exposure to physiological stresses: refrigeration (4°C for 24 hr), starvation (37°C for 48 hr), and desiccation (25°C for 4 days). The Log₁₀ CFU/ml and D-values indicated that survival rate of all the strains decreased significantly (p < .05) after desiccation as compared to those of the control condition (without stress exposure). However, cold stress increased the thermal tolerance of all strains at all temperatures (52, 55, and 58°C) as indicated by increased D-values. Among the tested strains, C. sakazakii strain N15 was found to be the most resistant to thermal treatment after each stress exposure as depicted by principal component analysis (PCA). No apparent correlation between thermal tolerance and starvation stress was observed. The findings indicate that prior exposure to stress conditions may induce cross protection to thermal treatment in C. sakazakii.     

Estimation of lung's air volume and its variations throughout respiratory CT image sequences

A respiratory image-sequence-segmentation technique is introduced based on a novel image-sequence analysis. The proposed technique is capable of segmenting the lung's air and its soft tissues followed by estimating the lung's air volume and its variations throughout the image sequence. Accurate estimation of these two parameters is very important in many applications related to lung disease diagnosis and treatment systems (e.g., brachytherapy), where the parameters are either the variables of interest themselves or are dependent/independent variables. The concept of the proposed technique involves using the image sequence's combined histogram to obtain a reasonable initial guess for the lung's air segmentation thresholds. This is followed by an optimization process to find the optimum threshold values that best satisfy the lung's air mass conservation and tissue incompressibility principles. These threshold values are consequently applied to estimate the lung's air volume and its variations throughout respiratory Computed Tomography (CT) image sequences. Ex vivo experiments were conducted on porcine left lungs in order to demonstrate the performance of the proposed technique. The proposed method was initially validated using a breath-hold CT image sequence with known air volumes inside the lung, where results show that the proposed technique outperforms single-histogram-based methods. This was followed by demonstrating the proposed technique's application in a 4-D-CT respiratory sequence, where the air volume inside the lung was unknown. Consistency of the obtained results in the latter experiment with tissue near incompressibility principle was validated. The results indicate a very good ability of the proposed method for estimating the lung's air volume and its variations in a respiratory image sequence.     

Steady state and transient photoconductivity measurements in a-Se90 − xSb10Inx thin films

Amorphous thin films of Se_90 − xSb₁₀In_x (0 ≤ x ≤ 15) have been prepared by electron beam evaporation method. The steady state and transient photoconductivity measurements on the thin films of Se_90 − xSb₁₀In_x (0 ≤ x ≤ 15) were carried out at different levels of light intensities (500 lx-5000 lx) at room temperature (301 K). The plot of photocurrent (I_ph) versus light intensity (F) follows a power law I_ph ∝ F^γ. The value of exponent γ lies between 0.5 and 1.0, which indicates there exists a continuous distribution of localized states in the mobility gap of Se_90 − xSb₁₀In_x (0 ≤ x ≤ 15) thin films. For transient photoconductivity, when the samples were illuminated with light, the photocurrent reaches the maximum value during the first 5 s of exposure time and thereafter, it starts decreasing and becomes stable after 15 min of exposure. This kind of phenomenon is termed as photo-degradation of photocurrent. The results have been explained on the basis of charged defect model and the intercluster interaction model. The magnitude of photocurrent of the system a-Se₇₅Sb₁₀In₁₅ is higher than the parent system a-Se₉₀Sb₁₀. The photosensitivity shows a minimum value at 5 atomic percentage of indium (In) concentration, which is explained based on chemically ordered network model and the topological model.     

Use of tergitol-7 in photogalvanic cell for solar energy conversion and storage: Toluidine blue-glucose system

Photogalvanic effects were studied in a photogalvanic cell containing toluidine blue, glucose and tergitol-7 as a photosensitizer, reductant and surfactant, respectively. The photocurrent and photopotential generated by this system were 70 μA and 315 mV, respectively. The effects of different parameters on the electrical output of the cell were observed. Current/voltage characteristics of the cell have also been studied, and a mechanism has been proposed for the generation of photocurrent in photogalvanic cell.     

Microbial screening of copolymers of 2,4‐dichlorophenyl methacrylate with N‐vinylpyrrolidone: synthesis and characterization

Copolymers of 2,4‐dichlorophenyl methacrylate and hydrophilic monomer (N‐vinylpyrrolidone) were synthesized with different feed ratios using dimethylformamide as solvent and 2,2′‐azobisisobutyronitrile as initiator at 70 °C. The copolymers were characterized by IR spectrometry. Copolymer compositions were determined by UV spectrometry. The monomer reactivity ratios were determined by applying the conventional linearization method of Fineman‐Ross. Gel permeation chromatography was employed for determining molecular weights and polydispersity indexes. Thermogravimetric analyses of polymers were carried out in nitrogen atmosphere. Homo‐ and copolymers were tested for their antimicrobial properties against selected microorganisms. © 2003 Society of Chemical Industry     

Synthesis and neutron structural studies of (Pb/Cu)-1201 superconductor

A 1201-phase superconductor (Pb_0.5Cu_0.5)SrLaCuO_5± exhibiting a zero-resistance (R=0) state at 21 K has been synthesized. Neutron Rietveld refinement of the structure shows substantial oxygen disorder in the (Pb/Cu)-O(3) monolayer and excess occupancy of oxygen at the O(3) sites. The superconducting behavior of (Pb_0.5Cd_0.5)SrLaCuO_5± , prepared under identical conditions, yields a value ofT _c (R=0) equal to 24 K. The presence of extra oxygen appears to be responsible for trapping of holes within the rock-salt (Pb/Cu)-O(3).     

Neutron structural investigations of Y1?xCaxBa2Cu3?yCoyO7±δ

The results of a systematic powder neutron study on Y_1–x CaxBa₂Cu_3–y Co _y O_7± for A (x=y=0), B (x=0;y=0.2), C (x= 0;y=0.4), D (x=y=0.2), and E (x=y=0.4) are investigated with a view to understanding the relation between the structural parameters and superconductivity. Rietveld refinements of the structures show that: (a) Co substitutes at the chain Cu(1) sites only, except for sample E, where the presence of a minor amount of Co at the planar Cu(2) site cannot be ruled out; (b) Co substitution reduced thec-parameter, which is reduced even further upon substitution of Ca at the Y-sites; (c) the occupancy factors of the chain O(1) site indicate an average coordination of 4.8 and 5.1 for Co for samples B and C, but only 4 for D and E; (d) Cu/Co(1) atoms for B and C display large thermal parameters, suggesting a displacement from their ideal centrosymmetric location; (e) the apical Cu(1)-O(4) bond lengthens upon substitution of Co in samples B and C but undergoes shortening upon substitution of Ca in the case of samples D and E. The apical Cu(2)-O(4) bond, on the other hand, shows just the opposite trend; (f) samples D and E show a reduction in the separation of CuO₂ layers and their oxygen content; and (e) the bond valence of the Cu(2) ion shows the lowest value of 2.127 for the nonsuperconducting sample C.     

Resin-tooth interfacial morphology and sealing ability of one-step self-etch adhesives: microleakage and SEM study

OBJECTIVES: To compare microleakage of three self‐etch adhesives and to analyze enamel surface morphology and interfacial morphology of resin–enamel and resin–dentin interface under scanning electron microscope (SEM). EXPERIMENTAL DESIGN: Study was conducted in 65 extracted human premolars. Class V cavities were prepared in 45 teeth and assigned to three groups (n = 15) according to three self‐etch adhesives (OptiBond All‐in‐One, iBond, and Adper Prompt L‐Pop). After restoration, 10 samples from each group were used to assess microleakage at enamel and dentin margin. Five samples from each group were used for analysis of interfacial morphology at resin–enamel and resin–dentin interface under SEM. Remaining 20 teeth were used to prepare flat enamel buccal surfaces to analyze the difference in surface morphology after treatment with three adhesives (n = 5 each) and 36% phosphoric acid treatment (n = 5). PRINCIPAL OBSERVATIONS: At enamel margin, Prompt L‐Pop depicted least leakage of all the three adhesives and also showed best interfacial adaptation under SEM. At dentin margin, OptiBond All‐in‐One showed significant less leakage than iBond and Prompt L‐Pop. On flat enamel surface, phosphoric acid produced the most retentive etching pattern when compared with the three adhesives. CONCLUSION: Prompt L‐Pop showed the best bonding effectiveness in enamel, whereas OptiBond All‐in‐One performed significantly better in dentin. Microsc. Res. Tech. 2012. © 2012 Wiley Periodicals, Inc.     

TRAM: Technique for resource allocation and management in fog computing environment

The Journal of Supercomputing - The traditional cloud computing technology provides services to a plethora of applications by providing resources. These services support numerous industries for...     

A potential antitumor drug (arginine deiminase) reengineered for efficient operation under physiological conditions

Arginine deiminase (ADI, EC 3.5.3.6) is a potential antitumor drug for the treatment of arginine‐auxotrophic tumors such as hepatocellular carcinomas (HCCs) and melanomas, and studies on human lymphatic leukemia cell lines have confirmed that ADI has antiangiogenic activity. Recent studies showed that a combination of taxane and ADI‐PEG20, which induces caspase‐independent apoptosis, is more effective than taxane monotherapy for prostate cancer. The main limitation of ADI from Pseudomonas plecoglossicida (PpADI) and of many other ADI enzymes lies in their pH‐dependent activity profile. PpADI has a pH optimum at 6.5 and a pH shift from 6.5 to 7.5 results in an ～80 % activity drop (the pH of human plasma is 7.35 to 7.45). In 2010, we reported a proof of concept for ADI engineering by directed evolution that resulted in variant M2 (K5T/D44E/H404R). M2 has a pH optimum of pH 7.0, a fourfold higher k_cat value than the wild‐type PpADI (pH 7.4, 0.5 M phosphate buffer), and an increased K_m value for substrate arginine. In our latest work, variants M5 (K5T/D38H/D44E/A128T/H404R) and M6 (K5T/D38H/D44E/A128T/E296K/H404R) were generated by directed evolution by employing PBS buffer (pH 7.4), which mimics physiological conditions. The S_0.5 value of parent M3 (K5T/D44E/A128T/H404R) decreased from 2.01 to 1.48 mM (M5) and 0.81 mM (M6). The S_0.5 value of M6 (0.81 mM ) is lower than that of wild‐type PpADI (1.30 mM ); the k_cat values improved from 0.18 s^?1 (wild‐type PpADI) to 17.56 s^?1 (M5, 97.6‐fold) and 11.64 s^?1 (M6, 64.7‐fold).