SciCombinator

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Concept: Hydrochloric acid

171

BACKGROUND: The purpose was to investigate the effects of one dose of NaHCO3 per day for five consecutive days on cycling time-to-exhaustion (Tlim) at ‘Critical Power’ (CP) and acid–base parameters in endurance athletes. METHODS: Eight trained male cyclists and triathletes completed two exercise periods in a randomized, placebo-controlled, double-blind interventional crossover investigation. Before each period, CP was determined. Afterwards, participants completed five constant-load cycling trials at CP until volitional exhaustion on five consecutive days, either after a dose of NaHCO3 (0.3 g.kg-1 body mass) or placebo (0.045 g.kg-1 body mass NaCl). RESULTS: Average Tlim increased by 23.5% with NaHCO3 supplementation as compared to placebo (826.5 +/- 180.1 vs. 669.0 +/- 167.2 s; P = 0.001). However, there was no time effect for Tlim (P = 0.375). [HCO3-] showed a main effect for condition (NaHCO3: 32.5 +/- 2.2 mmol.l-1; placebo: 26.2 +/- 1.4 mmol.l-1; P < 0.001) but not for time (P = 0.835). NaHCO3 supplementation resulted in an expansion of plasma volume relative to placebo (P = 0.003). CONCLUSIONS: The increase in Tlim was accompanied by an increase in [HCO3-], suggesting that acidosis might be a limiting factor for exercise at CP. Prolonged NaHCO3 supplementation did not lead to a further increase in [HCO3-] due to the concurrent elevation in plasma volume. This may explain why Tlim remained unaltered despite the prolonged NaHCO3 supplementation period. Ingestion of one single NaHCO3 dose per day before the competition during multiday competitions or tournaments might be a valuable strategy for performance enhancement.Trial registration: ClinicalTrials.gov Identifier: NCT01621074.

Concepts: Clinical trial, Carbonate, Bicarbonate, Acidosis, Sodium bicarbonate, Hydrochloric acid, Sodium carbonate, Ammonium bicarbonate

49

Capabilities in health monitoring enabled by capture and quantitative chemical analysis of sweat could complement, or potentially obviate the need for, approaches based on sporadic assessment of blood samples. Established sweat monitoring technologies use simple fabric swatches and are limited to basic analysis in controlled laboratory or hospital settings. We present a collection of materials and device designs for soft, flexible, and stretchable microfluidic systems, including embodiments that integrate wireless communication electronics, which can intimately and robustly bond to the surface of the skin without chemical and mechanical irritation. This integration defines access points for a small set of sweat glands such that perspiration spontaneously initiates routing of sweat through a microfluidic network and set of reservoirs. Embedded chemical analyses respond in colorimetric fashion to markers such as chloride and hydronium ions, glucose, and lactate. Wireless interfaces to digital image capture hardware serve as a means for quantitation. Human studies demonstrated the functionality of this microfluidic device during fitness cycling in a controlled environment and during long-distance bicycle racing in arid, outdoor conditions. The results include quantitative values for sweat rate, total sweat loss, pH, and concentration of chloride and lactate.

Concepts: Blood, Chemistry, PH, Hydronium, Perspiration, Exocrine system, Hydrochloric acid, Wireless network

28

Carbon nanomaterials are robust and possess fascinating properties useful for separation technology applications, but their scalability and high salt rejection when in a strong cross flow for long periods of time remain challenging. Here, we present a graphene-based membrane that is prepared using a simple and environmentally friendly method by spray coating an aqueous dispersion of graphene oxide/few-layered graphene/deoxycholate. The membranes were robust enough to withstand strong cross-flow shear for a prolonged period (120 h) while maintaining NaCl rejection near 85% and 96% for an anionic dye. Experimental results and molecular dynamic simulations revealed that the presence of deoxycholate enhances NaCl rejection in these graphene-based membranes. In addition, these novel hybrid-layered membranes exhibit better chlorine resistance than pure graphene oxide membranes. The desalination performance and aggressive shear and chlorine resistance of these scalable graphene-based membranes are promising for use in practical water separation applications.

Concepts: Water, Sodium chloride, Nanomaterials, Graphene, Chlorine, Chemical engineering, Hydrochloric acid, Scalability

28

The characterization of a spore laccase from Bacillus vallismortis fmb-103, isolated from textile industry disposal sites, is described. The activity was 6.5U/g of dry spore with ABTS as the substrate. The enzyme was quite stable at high temperature. It retained more than 90% of its initial activity after 10h at 70°C. The enzyme demonstrated broad pH stability in both acidic and alkaline conditions. There was almost no activity loss at pH 3 over an extended period of time, and the relative activity remained at 82% and 38% at pH 7 and pH 9 after 10days. NaN(3), SDS, l-cysterine, Dithiothreitol, EDTA and NaCl inhibit the enzyme activity. Triphenylmethane dyes, including malachite green, brilliant green and aniline blue were efficiently degraded by the enzyme after 24h in combination with a mediator with efficiencies of 76.84%, 96.56% and 81.17%, respectively. The reusability of spore laccase for decolorization dyes was also examined.

Concepts: Acid, Enzyme, PH, Sodium hydroxide, Base, PH indicator, Triarylmethane dyes, Hydrochloric acid

27

Bimetallic iron nanoparticles have mostly been applied to the degradation of chlorinated compounds in the aqueous phase. In this study, the degradation of pentachlorophenol (PCP) spiked into sandy soil is considered as a first exploratory step for remediating PCP in real contaminated soil using a commercial preparation of bimetallic iron (Trade name BioCAT). After 21 days of treatment a PCP removal efficiency of 90% was achieved, along with 70% dechlorination efficiency, for a dosage of 600mg BioCAT slurry/kg soil. Degradation of PCP by BioCAT follows first order kinetics in PCP. Stepwise dechlorination is the main pathway of PCP elimination from soil slurries contacted with BioCAT. Such dechlorination is confirmed by the appearance of intermediate products, as well as by release of chlorides. Additionally, the increasing pH value and the rapid decrease of the oxidation/reduction potential (ORP) also attest to the reductive dechlorination of PCP. The reaction products comprehend lower chlorinated phenols, including three TeCP isomers, four TrCP isomers, four DCP isomers, two MCP isomers and phenol. These findings indicate that BioCAT could be applied for field treatment of PCP-contaminated soil under ambient conditions.

Concepts: Enzyme, Water, Environmental remediation, Acid dissociation constant, Phenols, Hydrochloric acid, Anthocyanin, Environmental chemistry

27

Aqueous core-silica shell nanocapsules were successfully prepared using liquid droplets containing transition-metal salt as templates in inverse miniemulsions. The formation of the silica shell was attributed to the interfacial deposition of silica species induced by the presence of the transition-metal salt. In addition to the control of the particle morphology, the incorporated transition-metal salts could be used to derivatize the particles and confer additional functionalities to the hollow silica particles. To demonstrate the derivatization, the magnetic hollow silica particles were prepared by converting iron salts to magnetic iron oxides by heat treatment. The particle morphology, size, and size distribution were characterized by transmission electron microscopy and scanning electron microscopy. The results show that the particle properties strongly depend on the type and the amount of salts, the amount of tetraethoxysilane (TEOS), the pH of the droplets, and the ratios of 2-hydroxyethyl methacrylate to aqueous HCl solution. The specific surface area and pore properties were characterized by N2 sorption measurements. The pore properties and specific surface area could be tuned by varying the amount of salt. Levels of elements and of iron oxides in the magnetic hollow particles were measured by energy-dispersive X-ray spectroscopy. Iron was distributed homogenously with silicon and oxygen in the sample. The magnetization measured by a magnetic property measurement system confirmed the successful conversion of the iron salts to magnetic iron oxides.

Concepts: Electron, Oxygen, Water, Measurement, Transmission electron microscopy, Scanning electron microscope, Silicon dioxide, Hydrochloric acid

27

We compared potential pre-concentration techniques for Nannochloropsis gaditana (Nng) by testing natural sedimentation; flocculation with aluminium sulphate, polyaluminium chloride and chitosan; and induced pH. Promising flocculation efficiencies and concentration factors were obtained in a short time with alkalinity-induced flocculation at an adjusted pH of 9.7 and with chitosan at an adjusted pH of 9.9 using a concentration of 30mgL. The sedimentation rates of alkalinity-induced flocculation were also evaluated. Additionally, viscosity, particle size distribution and Ca/Mg ions were analysed for pre-concentrated samples of N. gaditana (Nng) and the previously studied Phaeodactylum tricornutum (Pht) which were obtained by various different harvesting methods under optimal conditions. The rheological properties of the concentrated algae suspensions of two microalgal species showed Newtonian behaviour. The mean diameters of the flocs were between 39 and 48μm. The Ca/Mg analysis showed that Mg is the triggering ion for alkalinity-induced flocculation in the conditions studied.

Concepts: Blood, Aluminium, Ion, Particle size distribution, Phaeodactylum tricornutum, Flocculation, Hydrochloric acid, Aluminium chlorohydrate

25

Monitoring stationary source emissions for heavy metals generally requires the use of quartz filters to collect samples because of the high temperature and high moisture sampling environment. The documentary standard method sample preparation technique in Europe, EN 14385, uses digestion in hydrofluoric acid and nitric acid (HF/HNO3) followed by complexing with boric acid (H3BO3) prior to analysis. However, the use of this method presents a number of problems, including significant instrumental drift during analysis caused by the matrix components, often leading to instrument breakdown and downtime for repairs, as well as posing significant health and safety risks. The aim of this work was to develop an alternative sample preparation technique for emissions samples on quartz filters. The alternative techniques considered were: (i) acid digestion in a fluoroboric acid (HBF4) and HNO3 mixture and (ii) acid extraction in an aqua regia (AR) mixture (HCl and HNO3). Assessment of the effectiveness of these options included determination of interferences and signal drift, as well as validating the different methods by measurement of matrix certified reference materials (CRMs), and comparing the results obtained from real test samples and sample blanks to determine limits of detection. The results showed that the HBF4/HNO3 mixture provides the most viable alternative to the documentary standard preparation technique.

Concepts: Acids, Silicon, Standard, Heavy metal music, Nitric acid, Madchester, Aqua regia, Hydrochloric acid

24

Herein, we have demonstrated a rapid and scalable synthesis of six new imine-linked highly porous and crystalline COFs which showcased exceptionally high chemical stability in harsh environments including conc. H2SO4 (36N), conc. HCl (12N) and NaOH (9N).This is because of the presence of strong interlayer C-H***N hydrogen bonding among the individual layers which provides significant steric hindrance and a hydrophobic environment around the imine (-C=N-) bonds thus preventing their hydrolysis in such abrasive environment. These COFs were further converted into porous, crystalline, self-standing and crack-free COF membranes (COFMs) with extremely high chemical stability for their potential applications for sulfuric acid recovery. Also, the as-synthesized COFMs exhibit unprecedented permeance for acetonitrile (280 Lm-2h-1bar-1) and acetone (260 Lm-2h-1bar-1).

Concepts: Oxygen, Hydrogen, Petroleum, Atom, Carbon, Sulfuric acid, Hydrochloric acid, Strong acid

20

In June 2015, personnel from California’s Contra Costa Health Services Environmental Health and Hazardous Materials (hazmat) divisions were alerted to a possible chemical release at a swimming pool in an outdoor municipal water park. Approximately 50 bathers were in the pool when symptoms began; 34 (68%) experienced vomiting, coughing, or eye irritation. Among these persons, 17 (50%) were treated at the scene by Contra Costa’s Emergency Medical Services (EMS) and released, and 17 (50%) were transported to local emergency departments; five patients also were evaluated later at an emergency department or by a primary medical provider. Environmental staff members determined that a chemical controller malfunction had allowed sodium hypochlorite and muriatic acid (hydrochloric acid) solutions to be injected into the main pool recirculation line while the recirculation pump was off; when the main recirculation pump was restarted, toxic chlorine gas (generated by the reaction of concentrated sodium hypochlorite and muriatic acid) was released into the pool. A review of 2008-2015 California pesticide exposure records identified eight additional such instances of toxic chlorine gas releases at public aquatic venues caused by equipment failure or human error that sickened 156 persons. Chemical exposures at public aquatic venues can be prevented by proper handling, storage, and monitoring of pool chemicals; appropriate equipment operation and maintenance; training of pool operators and staff members on pool chemical safety; and reporting of chemical exposures.

Concepts: Hydrogen, Sodium chloride, Chlorine, Hypochlorous acid, Hydrogen chloride, Hydrochloric acid, Swimming pool, Sodium carbonate