A scoping study characterizing prevalence, risk factor and intervention research, published between 1990 and 2010, for microbial hazards in leafy green vegetables

A scoping study was conducted to identify all published prevalence, risk factor, and intervention research investigating 16 microbial hazards in leafy green vegetables and to evaluate the volume, main characteristics, basic aspects of methodological soundness and/or reporting, and the main knowledge gaps and research needs. Our study included a comprehensive literature search, a replicable two-level relevance screening (abstract and article levels), and a two-phase quality assessment and data extraction (article level). All steps were conducted by two independent reviewers following general principles of systematic review methodology. From the initial 7961 citations, 657 articles were relevant, reporting one or more research themes: prevalence (314 studies), risk factor (472) and intervention research (269). These articles were published in 190 different scientific journals, 15% between 1990 and 2000, and the remaining 85% after year 2000. Sixty-five percent of studies was conducted in the USA, Canada, or Europe. Over 70% of all studies investigated lettuce. Collectively, four leafy greens (lettuce, cabbage, spinach, and fresh leafy herbs) and microorganism (Escherichia coli, Salmonella, Listeria and coliforms) combinations accounted for almost 80% of relevant studies. Forty-one percent of the research was conducted at the processing stage of production. Lack of reporting sufficient data and/or replicable laboratory protocols (first phase assessment) resulted in exclusion of 60% of relevant articles. In total, 231 papers were retained following second phase quality evaluation, and only 152 (20% of all relevant articles) met all ranking criteria. A lack of well designed, executed, and reported prevalence studies with sampled populations representative of the target populations and of experimental studies investigating the efficacy of intervention(s) under real-life conditions was observed. A limited number of articles investigating commonly accepted important risk factors, for example worker hygiene and health, equipment sanitation, and wildlife, was identified. We highlight research areas with the data potentially feasible for full systematic review-meta-analysis methodology and areas warranting additional investigation. The resulting information is necessary for the establishment of evidence-informed guidelines for food safety enhancement.     

Modification of hydrophilic polymer network to design a carrier for a poorly water-soluble substance

pH sensitive, nontoxic, and biocompatible poly(methacrylic) acid (PMAA) based soft networks have been extensively used in the design of systems for targeted drug delivery. Still, their highly hydrophilic nature limits their potential to be used as a carrier of poorly water-soluble substances. With the aim to overcome this limitation, the present study details a new approach for modification of PMAA based carriers using two amphiphilic components: casein and liposomes. The FTIR analysis revealed structural features of each component as well as the synergetic effect that originated from the formation of specific interactions. Namely, hydrophobic interactions between the poorly water-soluble model drug (caffeine) and casein enabled caffeine encapsulation and controlled release, while addition of liposomes ensured better control of the release rate. The morphological properties of the carriers, swelling behavior, and release kinetics of caffeine were investigated depending on the variable synthesis parameters (neutralization degree of methacrylic acid, concentration of caffeine, presence/absence of liposomes) in two different media simulating the pH environment of human intestines and stomach. The data obtained from in vitro caffeine release were correlated and analyzed in detail using several mathematical models, indicating significant potential of investigated carriers for targeted delivery and controlled release of poorly water-soluble substances.     

GISAXS and GIWAXS analysis of amorphous–nanocrystalline silicon thin films

Amorphous–nanocrystalline silicon thin films were deposited by Plasma Enhanced Chemical Vapor Deposition (PECVD) on glass substrate with various silicon nano-crystal size distributions and volume fractions. The samples were examined by Grazing Incidence Small Angle X-ray Scattering (GISAXS) and Grazing Incidence Wide Angle X-ray Scattering (GIWAXS) at the Austrian SAXS beamline (Synchrotron Elettra, Trieste) using an X-ray beam energy of 8 keV. The grazing incidence angle varied from the critical angle to 0.2° above the critical angle. This allowed the examination of the samples at different depths, and the distinction of the surface scattering contribution from the particles scattering in the bulk. The sizes of the “particles” obtained from the horizontal and vertical sections of 2D GISAXS patterns were between 2 nm and 6 nm. Since GISAXS is sensitive to electron density differences (contrast) between the scattering bodies and the surrounding matrix, it is not evident whether the particles are nano-crystals or just voids embedded in amorphous matrix. However, the size of the crystals calculated from the line-shape analysis of peaks in GIWAXS spectra and the crystal size distribution obtained from High-Resolution Transmission Electron Microscopy (HRTEM) images agree well with the size of “particles” estimated from GISAXS, strongly indicating that the observed particles are silicon nano-crystals.     

Repeating of positive and negative high electric field stress and corresponding thermal post-stress annealing of the n-channel power VDMOSFETs

We have subjected n-channel power VDMOSFETs to a positive and negative high electric field stress (HEFS) followed by biased annealing at 150 °C. Stress-induced defects have been monitored using midgap-subthreshold and charge-pumping techniques, the use of which in tandem has enabled an insight into behaviours of fixed and switching traps in the gate oxide and oxide/silicon interface. The repetition of the stress/annealing sequence has resulted in some quantitative but no qualitative differences in response compared to the original sequence. We have observed complex kinetics of different types the stress-induced defects during post-HEFS annealing, including an intriguing latent buildup of “true” interface traps. Comparison of post-HEFS and post-irradiation annealing data has indicated differences of the nature of defects induced by Fowler-Nordheim injection and irradiation in our samples.     

Exploitation of geothermal energy as a priority of sustainable energetic development in Serbia

The actual global economic crisis, including all other well-known problems of sustainable development, reflects the direction of development of all countries in the world. Serbia, as a European country in its early stage of development, is trying to synchronize its progress with experience of other countries from the field of sustainable development and in accordance with rules in the field of energetic and energetic efficiency, and, as well as to promote and develop the sector of use of renewable sources of energy. On the other hand, Serbia is a country which largely depends on import of all forms of energy, which to a great extent affects its economic stability. Therefore, in Serbia the strategy for development of energetic was imposed and it considers all the aspects of development of energetic until 2015 and it also defines the priorities which can be mostly seen in the choice of forms of alternative sources of energy. These sources, based on some criteria, can be considered the most convenient for a gradual substitution of energy which is gotten from the conventional sources. Taking into account strategically defined goals and domestic potentials which are at disposal, as well as economic parameters, an alternative source of energy of basic importance for the future exploitation on the territory of Serbia geothermal energy, was chosen. The research points to the fact that Serbia will be capable to respond adequately to Kyoto protocol demands and to the European rules regarding the substitution of a certain amounts of fossil fuels by the fuel origin from the raw biological materials. The research defines the existent and non-existent capacities and the assessment of positive effects of usage of geothermal energy. At the moment, 160 long holes are being exploited whose water temperature is around 60 °C (140 °F) and their heat power reach 160 MJ/s. It was stated that adequate exploitation of existing and new geothermal sources a yearly would save about 500,000 tons of fossil fuels what is proportional to the 10% of the today's heating system. The total amount of heat accumulated at geothermal deposit sites in Serbia, up to 3 km of depth, is two times greater than the total amount of heat that may be generated by burring all available coal reserves in Serbia. Price of electrical energy produced from geothermal springs is estimated to be between 9.2 US cents/kWh and 11.5 US cents/kWh. In order to support exploitation of geothermal energy (as well as all other renewable sources of energy) the decision that all the producers of energy from renewable sources get a status of privileged producers were made.     

Kinetic modeling and synergy quantification in sono and photooxidative treatment of simulated dyehouse effluent

The aim of this work was to explore the application of sulfate radical based advanced oxidation processes: photooxidation (UV/PMS/PS), sonooxidation (US/PMS/PS) and combined sono-photooxidation (US/UV/PMS/PS) for the mineralization of simulated dyehouse effluent (WW); using peroxymonosulfate (PMS) and persulfate (PS) as oxidants. Experiments were performed in a reaction vessel of a defined geometry and axially positioned source of UV-C radiation, all placed in the ultrasonic bath (35 kHz). Mathematical model of the process was developed according to the proposed degradation scheme. Decomposition of dyestuff (C.I. Reactive Violet 2, RV2 and C.I. Reactive Blue 7, RB7), surfactant (linear alkylbenzene sulfonate; hereafter: LAS) and auxiliary organic components was explored in three types of model wastewater: WW, simulated effluent excluding inorganic species (WW-IS) and model solution that consists of a specific compound (hereafter: compound model solutions). The influence of inorganic matrix (Cl⁻, CO₃²⁻/HCO₃⁻) was studied due to the corresponding quenching affinity toward HO and SO₄⁻ radicals. The efficiency of applied processes was evaluated and the response to combined phenomena (cavitation and irradiation) was quantified as synergy index, f_Syn. Sono-photooxidative treatment (US/UV/PMS/PS) of WW resulted in a partial mineralization and partial decolourization; approximately 40% of initial TOC and 30% of initial RB7 remained after 60 min of treatment, while RV2 and LAS molecule were completely decomposed. Circumstantially, the combined process increased the mineralization efficiency by a factor of 3 (f_Syn = 3.026).     

Development and characterization of thermosensitive hydrogels based on poly(N‐isopropylacrylamide) and calcium alginate

This work refers to the synthesis and characterization of thermosensitive hydrogels based on interpenetrating polymer networks (IPNs) of poly(N‐isopropylacrylamide) (PNIPAAm) and calcium alginate in the form of films. The influence of the crosslinking degree of PNIPAAm and alginate content on thermal, swelling, mechanical, and morphological properties of hydrogels is investigated in detail. Characterization of pure PNIPAAm hydrogels and IPN hydrogels was performed by FTIR, DSC, DMA, and SEM. In addition, the studies of equilibrium swelling behavior as well as swelling, deswelling, and reswelling kinetics are performed. The results obtained imply the benefits of synthesizing IPNs based on PNIPAAm and calcium alginate over pure PNIPAAm hydrogels. The presence of calcium alginate contributes to the improvement of mechanical properties, the deswelling rate of hydrogels, and the network porosity, without altering the thermosensitivity of PNIPAAm significantly. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

The simple one-step solvothermal synthesis of nanostructurated VO2(B)

VO₂(B) has been successfully synthesized by simple, facile and environmental friendly one-step solvothermal method using V₂O₅ and ethanol as a starting agent. Obtained micrometer-sized powder was composed from mutually welded nanosized rod-like, flat and snowflake structures. VO₂(B) powder was tested for possible application as anode material for aqueous lithium ion batteries. Lithium intercalation/deintercalation reaction has been carried out by cyclic voltammetry in a saturated aqueous solution of LiNO₃. At scan rate of 10 mV s^?1 very stable cyclic performance of such obtained VO₂ was established with discharge capacity around 184 mAh g^?1.     

Isothermal degradation of poly(3‐hydroxybutyrate)/organically modified montmorillonite nanocomposites

Polymer nanocomposites consisted of biodegradable poly(3‐hydroxybutyrate) (PHB) and organically modified montmorillonite Cloisite25A (OMMT), prepared by the solution‐casting method, were isothermally degraded for 120 min at 230, 235, 240, and 245°C in the nitrogen atmosphere. The addition of OMMT increases the thermal stability of PHB, and the most pronounced effect has the addition of 7 wt% of OMMT. Kinetic analysis was performed using reduced time plots and model‐free isoconversional methods. The empirical kinetic triplets (E, A, and g(α)) for the isothermal degradation of pure PHB and PHB/OMMT nanocomposites were determined. POLYM. COMPOS., 2010. © 2009 Society of Plastics Engineers     

Flavan‐3‐ol C‐glycosides – Preparation and model experiments mimicking their human intestinal transit

In order to study the human intestinal transit of flavan‐3‐ol C‐glycosides, several C‐glycosyl derivatives were prepared by non‐enzymatic reaction of (+)‐catechin with α‐D ‐glucose, α‐D ‐galactose and α‐D ‐rhamnose, respectively. In contrast to literature data, we propose that the reaction mechanism proceeds in analogy to the rearrangement of flavan‐3‐ols during epimerization under alkaline conditions. Four of the 12 synthesized flavan‐3‐ol C‐glycosides were incubated under aerobic conditions at 37°C using saliva (2 min) and simulated gastric juice (3 h). To simulate human intestine, the C‐glycosides were also incubated under anaerobic conditions at 37°C both in human ileostomy fluid (10 h) and colostomy fluid (24 h), respectively. The flavan‐3‐ol C‐glycosides under study, i.e. (+)‐epicatechin 8‐C‐β‐D ‐glucopyranoside (1a), (+)‐epicatechin 6‐C‐β‐D ‐glucopyranoside (1d), (+)‐catechin 6‐C‐β‐D ‐galactopyranoside (2b), (+)‐catechin 6‐C‐β‐D ‐rhamnopyranoside (3b) were analyzed in the incubation samples by HPLC‐DAD and HPLC‐DAD‐MS/MS. They were found to be stable in the course of incubation in saliva, simulated gastric juice and ileostomy fluid and underwent degradation in colostomy fluid. While the 6‐C‐β‐D ‐glucopyranoside 1d was completely metabolized between 2 and 4 h, decomposition of the 6‐C‐β‐D ‐galactopyranoside 2b reached only 16±2% within 4 h of incubation. Linear degradation rates of 1d and 2b in colostomy fluid differed significantly. As microbial metabolism of flavan‐3‐ols is known not to be influenced by the stereochemistry of the aglycon, varying degradation rates are ascribed to the effect of the sugar moiety. Based on these results we assume that flavan‐3‐ol C‐glycosides pass through the upper gastrointestinal tract (oral cavity, stomach and small intestine) unmodified and are then metabolized by the colonic microflora.