Saturated NaCl Solution Research Articles

Previous physicochemical stress exposures influence subsequent resistance of Escherichia coli O157:H7, Salmonella enterica, and Listeria monocytogenes to ultraviolet-C in coconut liquid endosperm beverage

This study investigated the influences of prior exposures to common physicochemical stresses encountered by microorganisms in food and food processing ecologies such as acidity, desiccation, and their combinations, on their subsequent susceptibility towards UV-C treatment in coconut liquid endosperm beverage. Cocktails of Escherichia coli O157:H7, Salmonella enterica, and Listeria monocytogenes were separately subjected to gradually acidifying environment (final pH4.46), exposed to abrupt desiccation by suspension in saturated NaCl solution (aw=0.85) for 4, 8, and 24h, and sequential acidic and desiccated stresses before suspending in the coconut beverage for UV-C challenge. The exposure times (D) and UV-C energy dose values (DUV-C) necessary to reduce 90% of the population of the different test organisms varied with previous exposures to different sublethal stresses, indicating possible influence of implicit microbial factors towards resistance to UV-C. All tested individual and combined stresses resulted in increased resistance, albeit some were not statistically significant. Non-stressed cells had D values of 3.2–3.5s, and corresponding DUV-C values of 8.4–9.1mJ/cm2. Cells exposed to previous acid stress had D values of 4.1–4.8s and corresponding DUV-C values of 10.7–12.5mJ/cm2. Prior exposure to desiccation resulted in D values of 5.6–7.9s and DUV-C values of 14.7–20.6mJ/cm2, while exposure to combined acid and desiccation stresses resulted in D values of 6.1–8.1s and DUV-C values of 15.9–21.0mJ/cm2. The D and DUV-C values of S. enterica after previous exposure to sequential acid (24h) and desiccation (24h) stresses were found significantly greatest, making the organism and physiological state an appropriate reference organism for the establishment of UV-C pasteurization process for the beverage.

Anisotropic effective permittivity of an ultrathin gold coating on optical fiber in air, water and saline solutions.

The optical properties of an ultrathin discontinuous gold film in different dielectric surroundings are investigated experimentally by measuring the polarization-dependent wavelength shifts and amplitudes of the cladding mode resonances of a tilted fiber Bragg grating. The gold film was prepared by electron-beam evaporation and had an average thickness of 5.5 nm ( ± 1 nm). Scanning electron imaging was used to determine that the film is actually formed of individual particles with average lateral dimensions of 28 nm ( ± 8 nm). The complex refractive indices of the equivalent uniform film in air at a wavelength of 1570 nm were calculated from the measurements to be 4.84-i0.74 and 3.97-i0.85 for TM and TE polarizations respectively (compared to the value for bulk gold: 0.54-i10.9). Additionally, changes in the birefringence and dichroism of the films were measured as a function of the surrounding medium, in air, water and a saturated NaCl (salt) solution. These results show that the film has stronger dielectric behavior for TM light than for TE, a trend that increases with increasing surrounding index. Finally, the experimental results are compared to predictions from two widely used effective medium approximations, the generalized Maxwell-Garnett and Bruggeman theories for gold particles in a surrounding matrix. It is found that both of these methods fail to predict the observed behavior for the film considered.

Radio-frequency capacitive discharge with non-flow-type and droplet-jet electrolytic electrodes

Results are presented from experimental studies of the shape, structure, and spectral characteristics of an RF capacitive discharge operating between a droplet-jet electrolytic electrode and an electrolytic cell in air at pressures of P = 103–105 Pa, as well as of a discharge burning between a copper rod and the surface of non-flow electrolyte at atmospheric pressure. It is found that, at voltages of U ≥ 3500 V, the multichannel discharge burning between the rod and the electrolyte (saturated solution of NaCl in technical water) surface transforms into a torch discharge. Specific features of the burning of a discharge with a droplet electrolytic electrode are investigated. Different forms of discharges burning on the surface of a copper tube and an electrolyte jet are revealed.

Removal of cadmium(II) from aqueous solutions by chemically modified maize straw

A new regenerable adsorbent was successfully prepared by modifying maize straw (MS) with succinic anhydride in xylene. The succinylated-maize straw (S-MS) was characterized by FTIR, solid-state MAS 13C NMR spectroscopy, SEM-EDX and point of zero charge analysis. NaS-MS was successfully obtained after deprotonating the carboxylic acid groups of S-MS by Na2CO3 solution. Batch experiments were carried out with NaS-MS for the removal of Cd(II). The effects of pH, adsorbent dosage, contact time, initial concentration and temperature were investigated. The experimental data were best described by a pseudo-second-order kinetics and Langmuir adsorption models. Thermodynamic parameters (ΔG, ΔH, and ΔS) were also calculated from data obtained from experiments performed to study the effect of temperatures. NaS-MS could be regenerated at least five times in saturated NaCl solution without any loss. Furthermore, ∼97% of adsorbed Cd(II) ions could be recovered as the metal oxide. Finally, the adsorption mechanism of NaS-MS was discussed.

The effect of environmental humidity on radiation-induced degradation of carrageenans

Better understanding of the chemistry of radiation-induced degradation is becoming of increasing importance on account of the utilization of polymeric materials in a variety of radiation environments as well as beneficial uses of degraded polymers. In this report the importance of environmental humidity on the degrading effect of radiation has been considered from the point of view of controlling the molecular weights of kappa- and iota-carrageenans. These two polysaccharides were irradiated in solid form under strictly controlled environmental humidity conditions by incubating and later irradiating the samples over saturated aqueous salt solutions of NaCl, NaNO3 and MgCl2. The degradation was followed in detail by a careful gel permeation chromatographic analysis of their respective molecular weights before and after irradiation. The chain scission yield values G(S) were found to decrease with the water adsorbed from environment at every absorbed dose in the range of 5–100kGy. On the other hand at very high water uptakes the yield of chain scission again increases especially at low doses. The decrease in degradation yield was attributed to the plastifying effect of water trapped in between the polymer chains facilitating the macroradical recombinations thus reducing the extent of chain scission. This study showed that although carrageenans were irradiated in solid form, the difference in their water uptake from changing environmental humidity has a profound effect in controlling their molecular weights by irradiation with ionizing radiation.

Effects of corrosive environments on properties of pultruded GFRP plates

Glass Fiber Reinforced Polymer (GFRP) composites have low permeability and high corrosion resistance. In recent years, as the use of GFRP in applications requiring high corrosion resistance has gradually expanded, its long-term performance in highly corrosive environments has caught public attention worldwide. Nevertheless, there is only limited theoretical research and accumulated test data on the corrosion resistance of GFRP. This paper analyses the long-term performance of GFRP in highly corrosive environments. Samples cut from pultruded GFRP profiles were exposed to alkaline, saline, and acidic solutions of different concentrations at 60°C. Additionally, the effects of acidic solutions at high temperature (90°C) were investigated. Flexural properties, changes in the flexural fracture mechanism, hardness, the rate of weight gain, changes in appearance, and scanning electron microscopy (SEM) images of fracture sections were analyzed over periods of 7, 15, 30 and 90days. Results indicate that flexural strength decreases with increased exposure time to both acidic and alkaline solutions. Under conditions of high concentration acidity and high temperature acidity, respectively, flexural strength decreases even more drastically. Additionally, it was found that saturated NaCl solution has little effect on GFRP.

Saturated salt accelerated aging and computerized analysis of seedling images to evaluate soybean seed performance

Seed deterioration causes losses to seed companies during the storage. For researches, the challenge has been to develop techniques which improve the seed longevity as well as laboratory analysis methods required for evaluating the evolution of deterioration in storage. This study had the objective of determining the effectiveness of the accelerated aging test with a saturated NaCl solution and Seed Vigor Imaging System (SVIS) analysis in checking soybean seed physiological in comparison with the recommended vigor tests. Soybean seeds from the cultivars BRS 184 and M-Soy 7908 RR were used, each of them were represented by six lots and stored for six months under two environment conditions. Seed physiological quality was checked every two months in storage through germination evaluations, accelerated aging (different methods), tetrazolium test (vigor and viability) seedling emergence, and SVIS analysis. The tetrazolium test is the most advisable method for evaluating soybean seed quality during storage. The results of the saturated salt accelerated aging test with NaCl at 41 ºC for 72 or 96 hours and the SVIS evaluation are also both efficient for estimating the physiological potential of seeds.

Qualidade fisiológica de sementes de diferentes árvores matrizes de Poincianella pyramidalis (Tul.) L. P. Queiroz

A catingueira [Poincianella pyramidalis (Tul.) L. P. Queiroz] é uma espécie arbórea endêmica do bioma Caatinga, bastante explorada devido ao seu potencial madeireiro, forrageiro e farmacológico. Face à relevância de sua importância, este trabalho teve o objetivo de avaliar a qualidade fisiológica das sementes entre matrizes de P. pyramidalis por meio de testes fisiológicos para fins de restauração ambiental. O estudo de campo foi conduzido na Fazenda Açude, município de Soledade-PB, onde foram selecionados 28 matrizes de catingueira, sendo as análises, realizadas no Laboratório de Análise de Sementes do Centro de Ciências Agrárias da Universidade Federal da Paraíba. Foram avaliadas as seguintes variáveis: teor de água, peso de mil sementes, número de sementes por quilograma, germinação, vigor {primeira contagem e índice de velocidade de germinação, comprimento e massa seca de plântulas, emergência, índice de velocidade e primeira contagem de emergência, envelhecimento acelerado (procedimento tradicional e solução saturada de NaCl)}. O delineamento experimental utilizado foi inteiramente casualizado, com os dados submetidos à análise de variância e a comparação entre as médias realizadas pelo teste de Scott-Knott a 5% de probabilidade. Com base nos resultados, a qualidade fisiológica das sementes de Poincianella pyramidalis varia mesmo quando oriundas de matrizes de uma única área de coleta; o teste de envelhecimento acelerado, utilizado no método tradicional, no período de 24 horas e à temperatura de 41 ºC mostra ser o teste de vigor mais eficiente na avaliação do potencial fisiológico das sementes de P. pyramidalis.

PTH-023 Paediatric Faecal Voc Analysis: Method Optimisation

IntroductionFaecal Volatile Organic Compounds (VOCs) analysis is an emerging diagnostic tool for gastrointestinal conditions because of its sampling ease and non-invasive characteristics. Solid phase micro-extraction (SPME) is often used with...

Testes para a seleção de populações de cenoura visando ao vigor e à longevidade das sementes

Populações de cenoura com sementes de maior qualidade fisiológica e potencial de armazenamento são de interesse para as empresas de sementes e horticultores. Assim, verificou-se a eficiência de alguns testes para a seleção de populações de cenoura com maior vigor e longevidade das sementes. Sementes de 50 progênies de meio-irmãos de cenoura tipo Brasília foram avaliadas quanto à massa de cem sementes, primeira contagem de germinação, germinação, dormência, envelhecimento acelerado com água e com solução saturada de NaCl. As sementes foram armazenadas com teor de água de 6,1±0,3% em embalagem hermética nas temperaturas de 15 e 25oC por 12 meses e a germinação foi avaliada trimestralmente. Os dados experimentais foram avaliados quanto à variância e correlações fenotípicas, genotípicas e ambientais; herdabilidade; coeficiente de variação genética e ganho por seleção. A seleção baseada na massa não deve ser utilizada, pois aumentaria a ocorrência de dormência nas sementes da geração seguinte. Os testes da primeira contagem, de germinação e de envelhecimento acelerado com água ou solução salina saturada podem ser utilizados para selecionar populações de cenoura com sementes de maior vigor e longevidade. O ganho genético estimado com a seleção para a germinação após 12 meses de armazenamento a 25°C foi de 14%.

A Universal and Cost-Effective Approach to the Synthesis of Carbon-Supported Noble Metal Nanoparticles with Hollow Interiors

Noble metal nanoparticles with hollow interiors and customizable shell compositions have immense potential for catalysis. Herein, we present a universal and cost-effective approach for the fabrication of carbon-supported Pt-containing noble metal nanoparticles with hollow interiors. This strategy starts with the synthesis of Pt-containing core shell Ag noble metal nanoparticles, which are then loaded on the carbon supports and refluxed in acetic acid to remove the original organic surfactant. The carbon-supported Pt-containing core shell Ag noble metal nanoparticles are subsequently agitated in saturated Na2S or NaCl solution to eliminate Ag from the core region, leading to the formation of Pt-containing noble metal nanoparticles with hollow interiors. In particular, the Pt-containing core shell Ag noble metal nanoparticles hollowed by NaCl on carbon support exhibit enhanced catalytic activity, whereas the hollowing by Na2S is a serious detriment to the catalytic activity of the resulting carbon-supported hollow nanoparticles for methanol oxidation.

Synthesis of Pt–Ag alloy triangular nanoframes by galvanic replacement reactions followed by saturated NaCl treatment in an aqueous solution

Pt–Ag alloy triangular nanoframes were prepared by a galvanic replacement (GR) reaction of Ag nanoprisms with H2PtCl6 in an aqueous solution. Their growth mechanisms were studied by observing transmission electron microscopic (TEM) and TEM-energy dispersed X-ray spectroscopy (EDS) images and surface plasmon resonance (SPR) bands. Results show that triangular Pt–Ag alloy prisms are slowly formed 12–48h after the addition of H2PtCl6. We found that after treatment using saturated NaCl solution is effective for the transformation of Ag-rich Pt–Ag alloy nanoprisms to Pt-rich Pt–Ag nanoframes.

Optimization study of BTEX extraction from soils spiked with two kinds of Brazilian diesel by HS SPME using Box–Behnken experimental design and multi-response analysis

In this work the main sorption conditions were optimized in the solid-phase microextraction (SPME) mode head-space (HS) for extraction of BTEX (benzene, toluene, ethylbenzene, and xylene isomers) from soils spiked with Brazilian conventional diesel and desulphurized diesel. Using a 100 μm poly(dimethylsiloxane) coating, the optimal exposure time was 4 min at 45 °C in saturated solution of NaCl (36 g per 100 mL). The resulting limits of detection (LODs) were between 0.002 and 0.02 mg kg−1. Statistics tools were used to assist in the selection of extraction variables in function to the best response (peak area) and the reproducibility (RSD%). Using Box–Behnken experimental design and desirability functions, an empirical model was developed through a response surface methodology to describe the effect of tested variables (temperature, time and ionic strength). Each experiment was carried out in triplicate. The most important result of this work is a fast and easy method (including solvent-free) that was optimized to determine BTEX in soils by the HS-SPME procedure combined with analysis of GC-FID that showed applicability in real samples (spiked soils with conventional Brazilian diesel and desulphurized diesel). It is postulated that this methodology that was intentionally developed to assess the natural biodegradation of BTEX in soils may also be used for environmental diagnostics in general.

Synthesis of Ag–Au and Ag–Pd alloy triangular hollow nanoframes by galvanic replacement reactions without and with post-treatment using NaCl in an aqueous solution

Ag–Au and Ag–Pd alloy triangular hollow nanoframes were prepared using galvanic replacement (GR) reactions of Ag nanoprisms with HAuCl4 and Na2PdCl4 in an aqueous solution. Their growth mechanisms were studied by observing transmission electron microscopic (TEM) and TEM-energy dispersed X-ray spectroscopic (EDS), XRD, and ultraviolet (UV)-visible (Vis)-near infrared (NIR) extinction spectral data. Results show that Ag–Au alloy triangular frames start with formation of a truncated prism, followed by expansion of a hollow structure to the interior of the prism, reformation of the triangular shape, and finally formation of a triangular frame at ambient temperature within a few minutes. On the other hand, triangular Ag–Pd alloy plates are slowly formed by the addition of Na2PdCl4 and heating at 100 °C for 30–120 min. Results show that post-treatment using saturated NaCl solution is effective for the transformation of Ag–Pd alloy nanoplates to Ag–Pd nanoframes. The difference in the formation of nanoframes is explained by the difference in the dealloying rates between Ag–Au alloys by AuCl4− and Ag–Pd alloys by Pd2+. XRD data suggested that hexagonally closed packed (hcp) layers are involved as major components of the triangular Ag–Au and Ag–Pd alloy nanoframes.

Combining thermodynamic simulations, element and surface analytics to study U(VI) retention in corroded cement monoliths upon >20 years of leaching

Retention or release of radionuclides in a deep geological repository for radioactive wastes strongly depends on the geochemical environment and on the interaction with near-field components, e.g. waste packages and backfill materials. Deep geological disposal in rock salt is one of the concepts considered for cemented low- and intermediate-level wastes. Long-term experiments were performed to observe the evolution of full-scale cemented waste simulates (doped with (NH4)2U2O7) upon reaction with relevant salt brines, e.g. MgCl2-rich and saturated NaCl solutions, and to examine the binding mechanisms of uranium. Throughout the experiments, concentrations of major solution components, uranium and pH values were monitored regularly and compared to thermodynamic equilibrium calculations, which indicate that close-to-equilibrium conditions have been achieved after 13–14years duration of the leaching experiments. Two of the full-scale cemented waste simulates were recovered from the solutions after 17–18years and studied by different analytical methods to characterize the solids, especially with respect to uranium incorporation. In drill core fragments of various lateral and horizontal positions of the corroded monoliths, U-rich aggregates were detected and analyzed by means of space-resolved techniques. Raman, μ-XANES and μ-XRD analyses of several aggregates demonstrate that they consist of an amorphous diuranate-type solid. Within error, calculated U solubilities controlled by Na-diuranate (Na2U2O7·H2O) are consistent with measured U concentrations in both, the NaCl and the MgCl2-system. Since uranophane occurs also in the corroded monoliths, it is proposed that a transition towards the thermodynamic equilibrium U(VI) phase is kinetically hindered.

Osmoadaptation Strategy of the Most Halophilic Fungus, Wallemia ichthyophaga, Growing Optimally at Salinities above 15% NaCl

Wallemia ichthyophaga is a fungus from the ancient basidiomycetous genus Wallemia (Wallemiales, Wallemiomycetes) that grows only at salinities between 10% (wt/vol) NaCl and saturated NaCl solution. This obligate halophily is unique among fungi. The main goal of this study was to determine the optimal salinity range for growth of the halophilic W. ichthyophaga and to unravel its osmoadaptation strategy. Our results showed that growth on solid growth media was extremely slow and resulted in small colonies. On the other hand, in the liquid batch cultures, the specific growth rates of W. ichthyophaga were higher, and the biomass production increased with increasing salinities. The optimum salinity range for growth of W. ichthyophaga was between 15 and 20% (wt/vol) NaCl. At 10% NaCl, the biomass production and the growth rate were by far the lowest among all tested salinities. Furthermore, the cell wall content in the dry biomass was extremely high at salinities above 10%. Our results also showed that glycerol was the major osmotically regulated solute, since its accumulation increased with salinity and was diminished by hypo-osmotic shock. Besides glycerol, smaller amounts of arabitol and trace amounts of mannitol were also detected. In addition, W. ichthyophaga maintained relatively small intracellular amounts of potassium and sodium at constant salinities, but during hyperosmotic shock, the amounts of both cations increased significantly. Given our results and the recent availability of the genome sequence, W. ichthyophaga should become well established as a novel model organism for studies of halophily in eukaryotes.

Accelerated aging in parsley seeds with and without salt solution and saturated

There are many gaps for the assessment of seed quality vegetable crops species, among these the parsley. In this context, the accelerated aging test is recognized as one of the most widely used to evaluate the effect of seeds of various crop species, being able to provide information with a high degree of consistency. Thus, the objective of the present study was to evaluate the methodology of accelerated aging test to check physiological potential of parsley seeds, as well as verify the possibility of using saline and saturated NaCl solution as an alternative for control of water uptake by seeds during the test without reducing yours sensitivity. Four lots of parsley seeds were tested for germination, seedling emergence, speed emergence and accelerated aging (periods of 48, 72 and 96 h, with or without the use of saturated and saline NaCl solution). The use of saline and saturated NaCl solution reduces water absorption by seeds of parsley during the accelerated aging test, resulting in a rate of deterioration is less pronounced and less drastic and results more uniform. Exposure for a period of 48 h is promising option for the evaluation of seed vigor.

Testing for the Influence of the Degree of Water Saturation of Concrete upon Chloride Diffusivity

In order to estimate the impact of the degree of water saturation of concrete to chloride ion diffusion coefficient, the experimental setup allows to measure chloride diffusion coefficient through nonsaturated concrete specimens with controlled degree of water saturated. The different degrees of water saturation of concrete specimens were obtained, by using saturated solutions of NaCl and KCl controlling the relative humidity, then applied Rapid Cloride Permeability Test method to measure the cloride diffusion coefficient. The test results show that chloride diffusion coefficient depends strongly on the degree of water saturation of concrete. Beside, this relationship shows the non-linear relationship, in which, chloride diffusion coefficient reachs the maximum value in fully saturated concrete specimens.

Influence of pozzolana on sulfate attack of cement stone affected by chloride ions

This study investigated the influence of natural pozzolana (opoka) additive on the hydration of Portland cement and the effects of pozzolana on sulfate attack of cement stone affected by chloride ions. In the samples, 25 % (by weight) of the Portland cement was replaced with pozzolana. The specimens were hardened for 28 days in water, and then one batch was soaked in a saturated NaCl solution and another in a 5 % Na2SO4 solution for 3 months at 20 °C. After being kept for 3 months in a saturated NaCl solution, samples were transferred to a 5 % Na2SO4 solution and kept under these conditions for 3 months. It was estimated that under normal conditions, pozzolana additive accelerated the hydration of calcium silicates and initiated the formation of CO3 2−–AFm; opoka also decreased the threshold pore diameter of hardened Portland cement paste. It was found that Cl– ions penetrate to monosulfoaluminate, form Friedel’s salt, and release SO4 2− ions, which react with unaffected monosulfoaluminate and form extra ettringite; when samples were transferred to the 5 % Na2SO4 solution, a greater quantity of new ettringite was formed. Meanwhile, pozzolana additive reduced the penetration of chloride and sulfate ions into the structure of Portland cement hydrates and inhibited sulfate attack of cement stone treated in a saturated NaCl solution.

Experimental study on fatigue behavior of corroded steel

The objective of this article is to provide datum to engineers on the fatigue behavior of corroded steel plate and the material used in this study was Q235 steel. The effect of corrosion on fatigue behavior of corroded steel was investigated by using Hydraulic Servo Universal Fatigue Testing Machine. The results indicate that the presence of corrosion pits, produced by the method of constant temperature and humidity with prior immersion in saturated NaCl solution for about 2min, significantly reduces the fatigue life of corroded steel. The relationship between (a) fractal dimension of roughness surface and fatigue life of corroded steel plate, (b) fractal dimension of roughness surface and corrosion ratio, and (c) corrosion ratio and fatigue life of corroded steel plate was also studied. In this paper, the fractal dimension refers to the fractal dimension of roughness surface but not to the fractal dimension of the fracture surfaces. In the end of this paper, the morphology characterization and fractography were also analyzed by using 3D Profiling and stereoscopic microscope, respectively.