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Journal of Microbiology and... Apr 2023Ultraviolet C (UV-C, 200-280 nm) light has germicidal properties that inactivate a wide range of pathogenic and spoilage microorganisms. UV-C has been extensively... (Review)
Review
Ultraviolet C (UV-C, 200-280 nm) light has germicidal properties that inactivate a wide range of pathogenic and spoilage microorganisms. UV-C has been extensively studied as an alternative to thermal decontamination of fruit juices. Recent studies suggest that the efficacy of UV-C irradiation in reducing microorganisms in fruit juices is greatly dependent on the characteristics of the target microorganisms, juice matrices, and parameters of the UV-C treatment procedure, such as equipment and processing. Based on evidence from recent studies, this review describes how the characteristics of target microorganisms (, type of microorganism/strain, acid adaptation, physiological states, single/composite inoculum, spore, etc.) and fruit juice matrices (, UV absorbance, UV transmittance, turbidity, soluble solid content, pH, color, etc.) affect the efficacy of UV-C. We also discuss the influences on UV-C treatment efficacy of parameters, including UV-C light source, reactor conditions (, continuous/batch, size, thickness, volume, diameter, outer case, configuration/arrangement), pumping/flow system conditions (, sample flow rate and pattern, sample residence time, number of cycles), homogenization conditions (, continuous flow/recirculation, stirring, mixing), and cleaning capability of the reactor. The collective facts indicate the immense potential of UV-C irradiation in the fruit juice industry. Existing drawbacks need to be addressed in future studies before the technique is applicable at the industrial scale.
Topics: Fruit and Vegetable Juices; Decontamination; Chemical Phenomena; Acids; Ultraviolet Rays; Fruit
PubMed: 36788459
DOI: 10.4014/jmb.2212.12022 -
Chemical & Pharmaceutical Bulletin 2012The reactions of (±)-α-epoxy drimenol (4) and (±)-α-epoxy drimenyl cyanide (6) with acids (proton acid or Lewis acid) selectively gave the rearranged aldehyde...
The reactions of (±)-α-epoxy drimenol (4) and (±)-α-epoxy drimenyl cyanide (6) with acids (proton acid or Lewis acid) selectively gave the rearranged aldehyde (±)-13 and (±)-15 having the hydroindane skeleton, respectively, while the reactions of (±)-4 and (±)-6 with Dibal-H selectively afforded the allyl alcohol (±)-14 and (±)-16, respectively. The reactions of (8aR)-6 and (8aS)-6 with Dibal-H were applied for the determination of the absolute structure of natural 7β-acetoxy-ent-labda-8(17),13(14)E-dien-15-ol (18). The reaction of (±)-α-epoxy bicyclofarnesol (5) and (8aS)-5 with proton acid selectively provided the rearranged ketol (±)- and (8aS)-31 having the hydroindane skeleton, respectively. The optically active (8aS)-31 was converted to the natural (9S)-austrodoric acid (33).
Topics: Acids; Biological Products; Epoxy Compounds; Molecular Conformation; Polycyclic Sesquiterpenes; Sesquiterpenes; Stereoisomerism
PubMed: 22466743
DOI: 10.1248/cpb.60.562 -
Chemistry (Weinheim An Der Bergstrasse,... Jan 2015Electronic circular dichroism and circularly polarized luminescence acid/base switching activity has been demonstrated in helicene-bipyridine proligand 1 a and in its...
Electronic circular dichroism and circularly polarized luminescence acid/base switching activity has been demonstrated in helicene-bipyridine proligand 1 a and in its "rollover" cycloplatinated derivative 2 a. Whereas proligand 1 a displays a strong bathochromic shift (>160 nm) of the nonpolarized and circularly polarized luminescence upon protonation, complex 2 a displays slightly stronger emission. This strikingly different behavior between singlet emission in the organic helicene and triplet emission in the organometallic derivative has been rationalized by using quantum-chemical calculations. The very large bathochromic shift of the emission observed upon protonation of azahelicene-bipyridine 1 a has been attributed to the decrease in aromaticity (promoting a charge-transfer-type transition rather than a π-π* transition) as well as an increase in the HOMO-LUMO character of the transition and stabilization of the LUMO level upon protonation.
Topics: 2,2'-Dipyridyl; Acids; Circular Dichroism; Electrons; Hydrogen-Ion Concentration; Luminescence; Luminescent Measurements; Models, Molecular; Organoplatinum Compounds; Polycyclic Compounds
PubMed: 25418503
DOI: 10.1002/chem.201405176 -
Journal of Oleo Science 2012The catalytic activity of acid activated montmorillonite in the esterification of free fatty acids (FFA) is reported. Standard Montmorillonite (MMT) type STx-1 provided...
The catalytic activity of acid activated montmorillonite in the esterification of free fatty acids (FFA) is reported. Standard Montmorillonite (MMT) type STx-1 provided by the Clay Mineral Society repository was activated using phosphoric, nitric and sulphuric acids under different conditions and the resulting materials were characterized and evaluated as catalysts in the methyl esterification of lauric acid. Blank reactions carried out in the absence of any added catalyst presented conversions of 32.64, 69.79 and 79.23%, for alcohol:lauric acid molar ratios of 60:1, 12:1 and 6:1, respectively. In the presence of the untreated clay and using molar ratios of 12:1 and 6:1 with 12% of catalyst, conversions of 70.92 and 82.30% were obtained, respectively. For the acid activated clays, conversions up to 93.08% of lauric acid to methyl laurate were obtained, much higher than those observed for the thermal conversion or using untreated montmorillonite. Relative good correlations were observed between the catalytic activity and the development of acid sites and textural properties of the resulting materials. Therefore, a simple acid activation was able to improve the catalytic activity and produce clay catalysts that are environmental friendly, cost effective, noncorrosive and reusable.
Topics: Bentonite; Catalysis; Lauric Acids; Nitric Acid; Phosphoric Acids; Sulfuric Acids
PubMed: 22975784
DOI: 10.5650/jos.61.497 -
Journal of Bacteriology Jun 1962Fite, George L. (U. S. Public Health Service Hospital, Carville, La.), Carolyn K. Wrinkle, and Donald J. Lartigue. Action of organic anhydrides on mycobacteria. J....
Fite, George L. (U. S. Public Health Service Hospital, Carville, La.), Carolyn K. Wrinkle, and Donald J. Lartigue. Action of organic anhydrides on mycobacteria. J. Bacteriol. 83:1305-1305. 1962.-The bacilli of leprosy, murine leprosy, and tuberculosis lose acid-fastness when treated with maleic anhydride, without loss of morphological integrity. Mycobacterium lepraemurium characteristically reacts only with maleic and not other anhydrides. Although the acid-fastness of M. tuberculosis, strain H(37)R(v), is altered by hot water and many hot organic solvents, it is destroyed by maleic anhydride with greater rapidity than that of M. lepraemurium. M. leprae lies intermediate to the other two in its reactivity. The reaction is probably a diene-anhydride synthesis, which in the case of M. lepraemurium may be of the Diels-Alder type.
Topics: Acids; Anhydrides; Animals; Mice; Mycobacterium; Mycobacterium leprae; Mycobacterium tuberculosis; Solvents; United States
PubMed: 13893334
DOI: 10.1128/jb.83.6.1301-1305.1962 -
International Journal of Environmental... Apr 2020In this study, we investigated the feasibility of using a solution of sulfuric acid and phosphoric acid as an extraction method for soil-washing to remove Cu, Pb, Zn,...
In this study, we investigated the feasibility of using a solution of sulfuric acid and phosphoric acid as an extraction method for soil-washing to remove Cu, Pb, Zn, and As from contaminated soil. We treated various soil particles, including seven fraction sizes, using sulfuric acid. In addition, to improve Cu, Pb, Zn, and As removal efficiencies, washing agents were compared through batch experiments. The results showed that each agent behaved differently when reacting with heavy metals (Cu, Pb, and Zn) and As. Sulfuric acid was more effective in extracting heavy metals than in extracting As. However, phosphoric acid was not effective in extracting heavy metals. Compared with each inorganic acid, As removal from soil by washing agents increased in the order of sulfuric acid (35.81%) < phosphoric acid (62.96%). Therefore, an enhanced mixture solution using sulfuric acid and phosphoric acid to simultaneously remove heavy metals and As from contaminated soils was investigated. Sulfuric acid at 0.6 M was adopted to combine with 0.6 M phosphoric acid to obtain the mixture solution (1:1) that was used to determine the effect for the simultaneous removal of both heavy metals and As from the contaminated soil. The removal efficiencies of As, Cu, Pb, and Zn were 70.5%, 79.6%, 80.1%, and 71.2%, respectively. The combination of sulfuric acid with phosphoric acid increased the overall As and heavy metal extraction efficiencies from the contaminated soil samples. With the combined effect of dissolving oxides and ion exchange under combined washings, the removal efficiencies of heavy metals and As were higher than those of single washings.
Topics: Arsenic; Environmental Pollution; Metals, Heavy; Phosphoric Acids; Soil; Soil Pollutants; Sulfuric Acids
PubMed: 32365892
DOI: 10.3390/ijerph17093133 -
Molecules (Basel, Switzerland) May 2019The gold abundance in basic rocks, which normally varies between 0.5 and 5 ppb, has served as a very important indicator in many geoscience studies, including those... (Review)
Review
The gold abundance in basic rocks, which normally varies between 0.5 and 5 ppb, has served as a very important indicator in many geoscience studies, including those focused on the planetary differentiation, redistribution of elements during the crustal process, and ore genesis. However, because gold is a monoisotopic element that exhibits a nugget effect, it is very difficult to quantify its ultra-low levels in rocks, which significantly limits our understanding of the origin of gold and its circulation between the Earth crust, mantle, and core. In this work, we summarize various sample digestion and combined preconcentration methods for the determination of gold amounts in rocks. They include fire assay, fire assay combined with Te coprecipitation and instrumental neutron activation analysis (INAA) or laser ablation inductively coupled plasma mass spectrometry, fusion combined with Te coprecipitation and anion exchange resins, dry chlorination, wet acid digestion combined with precipitation, ion exchange resins, solvent extraction, polyurethane foam, extraction chromatography, novel solid adsorbents, and direct determination by INAA. In addition, the faced challenges and future perspectives in this field are discussed.
Topics: Acids; Chemical Precipitation; Chemistry, Inorganic; Geologic Sediments; Gold; Liquid Phase Microextraction
PubMed: 31071914
DOI: 10.3390/molecules24091778 -
Dental Materials : Official Publication... Oct 2014To investigate the complex structural and dynamical conversion process of the amorphous-calcium-phosphate (ACP)-to-apatite transition in ACP based dental composite...
OBJECTIVE
To investigate the complex structural and dynamical conversion process of the amorphous-calcium-phosphate (ACP)-to-apatite transition in ACP based dental composite materials.
METHODS
Composite disks were prepared using zirconia hybridized ACP fillers (0.4 mass fraction) and photo-activated Bis-GMA/TEGDMA resin (0.6 mass fraction). We performed an investigation of the solution-mediated ACP-to-apatite conversion mechanism in controlled acidic aqueous environment with in situ ultra-small angle X-ray scattering based coherent X-ray photon correlation spectroscopy and ex situ X-ray diffraction, as well as other complementary techniques.
RESULTS
We established that the ACP-to-apatite conversion in ACP composites is a two-step process, owing to the sensitivity to local structural changes provided by coherent X-rays. Initially, ACP undergoes a local microstructural rearrangement without losing its amorphous character. We established the catalytic role of the acid and found the time scale of this rearrangement strongly depends on the pH of the solution, which agrees with previous findings about ACP without the polymer matrix being present. In the second step, ACP is converted to an apatitic form with the crystallinity of the formed crystallites being poor. Separately, we also confirmed that in the regular Zr-modified ACP the rate of ACP conversion to hydroxyapatite is slowed significantly compared to unmodified ACP, which is beneficial for targeted slow release of functional calcium and phosphate ions from dental composite materials.
SIGNIFICANCE
For the first time, we were able to follow the complete solution-mediated transition process from ACP to apatite in this class of dental composites in a controlled aqueous environment. A two-step process, suggested previously, was conclusively identified.
Topics: Acids; Calcium Phosphates; Composite Resins; Molecular Structure; Powder Diffraction
PubMed: 25082155
DOI: 10.1016/j.dental.2014.07.003 -
Current Opinion in Biotechnology Oct 2008The extremely thermoacidophilic archaea are a particularly intriguing group of microorganisms that must simultaneously cope with biologically extreme pHs (< or = 4) and... (Review)
Review
The extremely thermoacidophilic archaea are a particularly intriguing group of microorganisms that must simultaneously cope with biologically extreme pHs (< or = 4) and temperatures (Topt > or = 60 degrees C) in their natural environments. Their expanding biotechnological significance relates to their role in biomining of base and precious metals and their unique mechanisms of survival in hot acid, at both the cellular and biomolecular levels. Recent developments, such as advances in understanding of heavy metal tolerance mechanisms, implementation of a genetic system, and discovery of a new carbon fixation pathway, have been facilitated by the availability of genome sequence data and molecular genetic systems. As a result, new insights into the metabolic pathways and physiological features that define extreme thermoacidophily have been obtained, in some cases suggesting prospects for biotechnological opportunities.
Topics: Acids; Archaea; Archaeal Proteins; Cell Survival; Ecosystem; Hot Temperature; Hydrogen-Ion Concentration; Models, Biological; Signal Transduction
PubMed: 18760359
DOI: 10.1016/j.copbio.2008.08.001 -
Biochemistry and Molecular Biology... May 2020Undergraduate biochemistry students frequently find the quantitative treatment of weak acids and bases troublesome. Given the pK of a weak acid HA, for instance, many...
Undergraduate biochemistry students frequently find the quantitative treatment of weak acids and bases troublesome. Given the pK of a weak acid HA, for instance, many students struggle to calculate the pH of a solution of the conjugate base A at concentration C, pH(A , C). The traditional method involves calculating the base dissociation constant K and the artificial quantity pOH before reaching pH, but these steps increase the risk of mistakes and provide little insight into acid-base equilibria. The alternative method presented here allows students to calculate the pH of a weak base solution from the pK of its conjugate acid without calculating K and pOH, using a memorable relationship: pH(HA, C) + pH(A , C) = pK + 7.
Topics: Acids; Biochemistry; Humans; Hydrogen-Ion Concentration; Learning; Pharmacology; Students; Temperature; Water
PubMed: 32040240
DOI: 10.1002/bmb.21336