SciCombinator

Discover the most talked about and latest scientific content & concepts.

Concept: Base

225

The synchronization of two pendulum clocks hanging from a wall was first observed by Huygens during the XVII century. This type of synchronization is observed in other areas, and is fundamentally different from the problem of two clocks hanging from a moveable base. We present a model explaining the phase opposition synchronization of two pendulum clocks in those conditions. The predicted behaviour is observed experimentally, validating the model.

Concepts: Scientific method, Hypothesis, Das Model, Base, Problem of evil, Pendulum clock, Christiaan Huygens

156

To evaluate the evidence for a causal relationship between dietary acid/alkaline and alkaline water for the aetiology and treatment of cancer.

Concepts: Causality, Water, The Canon of Medicine, The Association, Philosophy of science, Base

30

To reduce the costs of maintaining a poliovirus immunization base in low-income areas, we assessed the extent of priming immune responses after the administration of inactivated poliovirus vaccine (IPV).

Concepts: Immune system, Vaccine, Vaccination, Polio vaccine, Immunology, Base, Poliovirus

28

There exists a misunderstanding on the TAED-activated peroxide system in the textile industry that H(2)O(2) used in excess of the stoichiometric amount could produce an addition effect on bleaching of cotton under alkaline conditions. In this study, a critical reinvestigation was carried out on the TAED-activated peroxide system for bleaching of cotton. It was found that the TAED-activated peroxide system achieved its best performance under near-neutral pH conditions. No addition effect was observed when an excessive amount of H(2)O(2) was used under alkaline conditions, which is probably due to the base-catalyzed bimolecular decomposition of peracetic acid and the nucleophilic attack by H(2)O(2) on peracetic acid. NaHCO(3) was shown to be a desired alkaline agent for maintaining near-neutral pH for the TAED-activated peroxide system. This study provides new insight into the application of the TAED-activated peroxide system for low-temperature bleaching of cotton under more environmentally benign conditions.

Concepts: Oxygen, Ammonia, Hydrogen peroxide, Cotton, PH, Textile, Base, Tetraacetylethylenediamine

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

28

Grape anthocyanins reacted with diacetyl, a secondary metabolite of microorganisms involved in winemaking, to form 10-acetyl-pyranoanthocyanins, a type of anthocyanin-derived pigments similar to other vitisin-type pyranoanthocyanins found in red wines. The structures of 10-acetyl-pyranomalvidin-3-β-O-glucoside and 10-acetyl-pyranopeonidin-3-β-O-glucoside were confirmed by spectroscopic methods (UV-vis, MS/MS, and NMR) after their synthesis and isolation. In contrast to other vitisin-type pyranoanthocyanins, the newly described 10-acetyl-pyranoanthocyanins exhibited differentiated color-related properties. They showed an important tendency to occur as colorless hemiacetals at C-10 under wine pH conditions, while co-occurrence of flavylium cation and quinoidal base yield a broad visible absorbance band around 510-520 nm. Moreover, they easily reacted with bisulfite in acidic aqueous solution (pH 2.0), but the expected bleaching was not observed. Bisulfite bonded to the carbonyl of 10-acetyl substituent instead the expected C-10 position of the pyranoanthocyanin core, thus giving rise to a red pigment hypsochromically shifted towards orangish nuances (maximum absorbances at 487-491 nm).

Concepts: Spectroscopy, Chemistry, Color, Vermilion, Wine, Oenology, Base, Anthocyanin

28

Multiple pH-sensitive composites have been prepared through non-covalently functionalizing chemically converted graphene (CCG) with chitosan. Chtiosan exhibits as polybases and CCG shows characteristics of polyacids. Owing to the synergistic effects of chitosan and CCG, chitosan decorated graphene (CS-G) presents a multiple pH-responsive behavior that it can be dispersed well whether in acidic or in basic solution but aggregated in near-neutral solution. After CS-G was modified through a controlled deposition and cross-linking process of chitosan, the resultant cross-linked chitosan decorated graphene (CLCS-G) can be converted to a different pH-sensitive material that disperses only in acidic solution. Both CS-G and CLCS-G present a reversible switching between dispersed and aggregated states with pH as a stimulus. The unique pH response mechanisms of CS-G and CLCS-G have been further investigated by zeta potential analysis. Based on the unique pH-responsive property of CS-G, a stable and repeatable pH-driven switch was developed for monitoring pH change.

Concepts: Acid, Chemistry, Polymer chemistry, Colloid, PH, Base, Cross-link, Thermoplastic

27

Silver nanoparticles were added into anaerobic batch reactors to enhance acidogenesis and fermentative hydrogen production simultaneously. The effects of silver nanoparticles concentration (0-200nmolL(-1)) and inorganic nitrogen concentration (0-4.125gL(-1)) on cell growth and hydrogen production were investigated using glucose-fed mixed bacteria dominated by Clostridium butyricum. The tests with silver nanoparticles exhibited much higher H2 yields than the blank, and the maximum hydrogen yield (2.48mol/molglucose) was obtained at the silver concentration of 20nmolL(-1). Presence of silver nanoparticles reduced the yield of ethanol, but increased the yield of acetic acid. The high silver nanoparticles had higher cell biomass production rate. Further study using the alkaline pretreated culture as inoculum was carried out to verify the positive effect of silver nanoparticles on H2 production. Results demonstrated that silver nanoparticles could not only increase the hydrogen yield, but reduce the lag phase for hydrogen production simultaneously.

Concepts: Oxygen, Hydrogen, Ethanol, Base, Fermentative hydrogen production, Hydrogen production, Dark fermentation, Biohydrogen

27

Endoscopic endonasal transpterygoid approaches (EETA) use the pneumatization of the sinonasal corridor to control lesions of the middle and posterior skull base. These surgical areas are complex and the required surgical corridors are difficult to predict.

Concepts: Forecasting, Base, Corridor

27

The present investigation was aimed at optimizing the conditions for preparing sulfated derivative of gum obtained from partially ripe fruits of Aegle marmelos. Elemental analysis, FTIR-ATR and NMR studies confirmed successful sulfation. The ratio of chlorosulfonic acid to pyridine exerted maximum influence on the degree of substitution followed by reaction temperature and reaction time. The sulfated derivative showed higher swelling in both acidic and alkaline pH as compared to unmodified gum. It also possessed higher negative zeta potential, higher viscosity, work of shear, firmness, consistency, cohesiveness and index of viscosity as compared to both unmodified gum as well as sodium alginate. Sulfated derivative was superior to unmodified gum and sodium alginate in terms of antimicrobial and anticoagulant activity. The sulfated sample appears to be a potential substitute over the unmodified gum sample and sodium alginate for modulating physicochemical properties of food and drug release dosage forms.

Concepts: Acid, Ratio, Cell wall, PH, Physical chemistry, Materials science, Base, Natural gum