Adsorption and Thermal Desorption of Volatile Organic Compounds in a Fixed Bed – Experimental and Modeling

Adsorption and thermal desorption dynamics of acetone in fixed-bed silica gel were studied experimentally and theoretically. The effect of process factors on adsorption and desorption performances was established. Acetone adsorption from air stream was performed by the dynamic (flowing gas) method in a laboratory setup at two levels of air superficial velocity (0.7 and 1.7 cm s^?1), temperature (30 and 40°C), and adsorbent particle diameter (0.21 and 0.54 cm). The values of saturation adsorption capacity (0.147–0.270 g g^?1) increased up to 78% and 36%, respectively, with a decrease in air velocity and adsorption temperature. Acetone thermal desorption from spent silica gel was studied in a thermobalance at three levels of process temperature (60, 70, and 80°C) and two values of particle size (0.21 and 0.54 cm). Equilibrium desorption efficiency (63–81%) was up to 14% larger for finer particles and increased with the desorption temperature. Kinetic models with relevant parameters adjusted based on experimental data were adopted to predict the dynamics of acetone adsorption and thermal desorption. The models simulated well the real conditions and could be applied to scale up and operate the adsorption columns used for air remediation.     

Physicochemical and Bioactive Compounds of ‘Cantaloupe’ Melon: Effect of Ozone Processing on Pulp and Seeds

Melon seeds are an important source of bioactive compounds, which are considered to be health beneficial. Therefore, the objective of this work was to assess the impact of gaseous ozone treatments (30 and 60 min) on melon seeds paste (nonedible part) and compare with the effect on pulp (edible part). Ozone treatments were evaluated in terms of physicochemical (color, pH, and soluble solids content) and nutritional profiles (total phenolics, total carotenoids, and total antioxidant capacity) of processed material. Results indicate that ozone has a different impact on the two fruit matrices, being seeds less affected by this preservation treatment.     

Thermal Decomposition of 2,4‐Dinitrobenzofuroxan and Some of Its Compounds with Metal Hydroxides

The kinetic regularities of the thermal decomposition of 2,4dinitrobenzofuroxan and its adducts with K, Na, and Cu hydroxides were studied. The variation in the reaction rate during the transformation and the relationship between the decomposition kinetics and the degree of filling of the vessel with the substance, the state of aggregation, and temperature were established. Possible mechanisms of the chemical reactions are considered on the basis of the kinetic data obtained, the compositions of gaseous and some condensed decomposition products, and an analysis of the element mass balance between the starting substance and products.     

Pine Bark and Green Tea Concentrated Extracts: Antioxidant Activity and Comprehensive Characterization of Bioactive Compounds by HPLC–ESI-QTOF-MS

The consumption of polyphenols has frequently been associated with low incidence of degenerative diseases. Most of these natural antioxidants come from fruits, vegetables, spices, grains and herbs. For this reason, there has been increasing interest in identifying plant extract compounds. Polymeric tannins and monomeric flavonoids, such as catechin and epicatechin, in pine bark and green tea extracts could be responsible for the higher antioxidant activities of these extracts. The aim of the present study was to characterize the phenolic compounds in pine bark and green tea concentrated extracts using high-performance liquid chromatography coupled to electrospray ionization mass spectrometry (HPLC–ESI-QTOF-MS). A total of 37 and 35 compounds from pine bark and green tea extracts, respectively, were identified as belonging to various structural classes, mainly flavan-3-ol and its derivatives (including procyanidins). The antioxidant capacity of both extracts was evaluated by three complementary antioxidant activity methods: Trolox equivalent antioxidant capacity (TEAC), ferric reducing antioxidant power (FRAP) and oxygen radical absorbance capacity (ORAC). Higher antioxidant activity values by each method were obtained. In addition, total polyphenol and flavan-3-ol contents, which were determined by Folin–Ciocalteu and vanillin assays, respectively, exhibited higher amounts of gallic acid and (+)-catechin equivalents.     

Estimation of Separation of Electrolytes and Organic Compounds by Nanofiltration Membranes Using an Irreversible Thermodynamic Modei

Nanofiltration separation has become a popular technique for removing large organic molecules and inorganic substances from water. It is achieved by a combination of three mechanisms: electrostatic repulsion, sieving and diffusion. In the present work, a modei based on irreversible thermodynamics is extended and used to estimate rejection of inorganic salts and organic substances. Binary systems are modeled, where the feed contains an ion that is much less permeable to the membrane as compared with the other ion. The two modei parameters are estimated by fitting the modei to the experimental data. Variation of these parameters with the composition of the feed is described by an empirical correlation. This work attempts to describe transport through the nanofiltration membranes by a simple model.     

Shock‐Wave Compression of Carbonyl Compounds

The state variables of material behind a shockwave front in carbonyl compounds are calculated. The following versions are considered: preservation of the starting compound, its decomposition to water, methane, and carbon, polymerization, etc. Calculation results are compared to experimental Hugoniots. Conversions of ketones, acids, and esters with characteristic times of 0.001–0.1 sec were observed at postshock temperatures of the starting compound above (1.1 – 1.3) · 10³K. Vapors of the compounds decomposed in firstorder reactions at temperatures above 2 · 10³ K over the same times. Conversions of the anhydrides of carboxylic acids were observed at postshock temperatures of the starting compound above 1.6 · 10³K. Their vapors decomposed in a firstorder reaction at about the same temperature.     

Schiff Based Silatranyl Compounds Exhibiting ‘Fe3+ and Mn2+ Fluorescence Dual Ion Sensing and Antibacterial Activity’

Silicon - The synthesis of different Schiff base substituted silatranes (1c–4c) was carried out from the corresponding organotrimethoxysilanes (OTMS) (1b–4b) under anhydrous atmospheric...     

Fluoride Removal from Aqueous Solutions by Magnesium,Nickel, and Cobalt Calcined Hydrotalcite‐like Compounds

Abstract

Magnesium, nickel and cobalt hydrotalcite‐like compounds (MgHT, NiHT, and CoHT), with similar M²⁺:Al³⁺ ratios were synthesized and characterized by XRD. It was confirmed from XRD that the materials have hydrotalcite‐like structure. MgHT, NiHT, and CoHT were calcined and treated with fluoride solutions in a batch system. F^? ions were determined in the remaining solutions using a fluoride ion selective electrode. The kinetics of the fluoride ions sorption on calcined hydrotalcite‐like compounds (CHT) was best described by the pseudo‐second order model and the equilibrium was reached in less than 300 minutes in all cases (MgCHT, NiCHT, and CoCHT). The sorption isotherms of the fluoride by hydrotalcite like compounds can be explained by the Langmuir‐Freundlich model and, the highest fluoride sorption capacity was obtained for NiCHT (1.202 mgF/gCHT). The fluoride removal from aqueous solutions by calcined hydrotalcite‐like compounds depends on the adsorption properties of the thermal decomposition products and the regeneration reaction mechanism of the hydrotalcite‐like compounds.     

Rhm Molding Compounds投资DVD设备

2001年5月,一个主要针对消费者的DVD试验工厂在德国的中部城市达姆施塔特开始运转。这个试验工厂是由Business Line Rohm MoldingCompounds与其合作伙伴——OK Media DiscService GmbH＆Co.KG共同设立的。工厂的“心脏”是Singulus的Spaceline DVD设备,在一定的生产条件下,该设备可以用PLEXIGLAS~(R)DQ501来生产DVDS和DVD9。此举的目的一方面是为了论证利用PLEXIGLAS~(R) DQ501 PMMA材料进行DVD制造的可行性,同时也是对在现行条件下用于生产未来格式的模塑料的一种开发。     

Isolation,Identification, and Quantification of Potential Defensive Compounds in the Viceroy Butterfly and its Larval Host–Plant,Carolina Willow

The viceroy-monarch and viceroy-queen butterfly associations are classic examples of mimicry. These relationships were originally classified as Batesian, or parasitic, but were later reclassified as Müllerian, or mutalistic, based on predator bioassays. The Müllerian reclassification implies that viceroy is unpalatable because it too is chemically defended like the queen and the monarch. However, unlike the queen and the monarch, the viceroy defensive chemistry has remained uncharacterized. We demonstrate that the viceroy butterfly (Limenitis archippus, Nymphalidae) not only sequesters nonvolatile defensive compounds from its larval host-plant, the Carolina willow (Salix caroliniana, Salicaceae), but also secretes volatile defensive compounds when disturbed. We developed liquid chromatography-mass spectrometry-mass spectrometry methods to identify a set of phenolic glycosides shared between the adult viceroy butterfly and the Carolina willow, and solid phase microextraction and gas chromatography-mass spectrometry methods to identify volatile phenolic compounds released from stressed viceroy butterflies. In both approaches, all structures were characterized based on their mass spectral fragmentation patterns and confirmed with authentic standards. The phenolics we found are known to deter predator attack in other prey systems, including other willow-feeding insect species. Because these compounds have a generalized defensive function at the concentrations we described, our results are consistent with the Müllerian reclassification put forth by other researchers based on bioassay results. It seems that the viceroy butterfly possesses chemical defenses different from its monarch and queen butterfly counterparts (phenolic glycosides vs. cardiac glycosides, respectively), an unusual phenomenon in mimicry warranting future study.     

Agronomical Parameters,Sugar Profile and Antioxidant Compounds of “Catherine” Peach Cultivar Influenced by Different Plum Rootstocks

The influence of seven plum rootstocks (Adesoto, Monpol, Montizo, Puebla de Soto 67 AD, PM 105 AD, St. Julien GF 655/2 and Constantí 1) on individual and total sugars, as well as on antioxidant content in fruit flesh of “Catherine” peaches, was evaluated for three years. Agronomical and basic fruit quality parameters were also determined. At twelve years after budding, significant differences were found between rootstocks for the different agronomic and fruit quality traits evaluated. The Pollizo plum rootstocks Adesoto and PM 105 AD seem to induce higher sweetness to peach fruits, based on soluble solids content, individual (sucrose, fructose and sorbitol) and total sugars. A clear tendency was also observed with the rootstock Adesoto, inducing the highest content of phenolics, flavonoids, vitamin C and relative antioxidant capacity (RAC). Thus, the results of this study demonstrate the significant effect of rootstock on the sugar profile and phytochemical characteristics of peach fruits. In addition, this work shows the importance of the sugar profile, because specific sugars play an important role in peach flavour quality, as well as the studied phytochemical compounds when looking for high quality peaches with enhanced health properties.     

On the results of the First All-Russian Conference “Sol-Gel Synthesis and Study of Inorganic Compounds,Hybrid Functional Materials,and Disperse Systems”

Chronicle

On the results of the First All-Russian Conference “Sol-Gel Synthesis and Study of Inorganic Compounds, Hybrid Functional Materials, and Disperse Systems”     

Organometallic Compounds: An Opportunity for Chemical Biology?

Organometallic compounds are renowned for their remarkable applications in the field of catalysis, but much less is known about their potential in chemical biology. Indeed, such compounds have long been considered to be either unstable under physiological conditions or cytotoxic. As a consequence, little attention has been paid to their possible utilisation for biological purposes. Because of their outstanding physicochemical properties, which include chemical stability, structural diversity and unique photo- and electrochemical properties, however, organometallic compounds have the ability to play a leading role in the field of chemical biology. Indeed, remarkable examples of the use of such compounds-notably as enzyme inhibitors and as luminescent agents-have recently been reported. Here we summarise recent advances in the use of organometallic compounds for chemical biology purposes, an area that we define as "organometallic chemical biology". We also demonstrate that these recent discoveries are only a beginning and that many other organometallic complexes are likely to be found useful in this field of research in the near future.     

Competitive Binding of Off-Flavor Compounds with Soy Protein and β-Cyclodextrin in a Ternary System: A Model Study

Removal of soy protein (SP)-bound 2-nonanone by β-cyclodextrin (βCD) was studied using an equilibrium dialysis technique. It was observed that in the presence of βCD, a significant (p < 0.05) amount of SP-bound 2-nonanone could be removed in a concentration-dependent manner. Up to 94% of SP-bound 2-nonanone was stripped from SP when 6 mM βCD was present in the system. However, in thermodynamic terms, the net standard free energy change for transfer of 2-nonanone from SP to βCD, i.e., \( \Updelta \Updelta G^\circ_{{{\text{SP}} \to \beta {\text{CD}}}} \), was essentially zero, implying that the apparent equilibrium binding constant for the formation of βCD–2-nonanone complex was essentially same as that for the SP–2-nonanone complex formation in the ternary system. This indicated that stripping-off of 2-nonanone from SP by βCD was driven by the mass action ratio. Based on these results, it is shown that βCD can be used effectively for removing SP-bound off-flavor carbonyl compounds.     

Rhinacanthus nasutus Extracts Prevent Glutamate and Amyloid-β Neurotoxicity in HT-22 Mouse Hippocampal Cells: Possible Active Compounds Include Lupeol, Stigmasterol and β-Sitosterol

The Herb Rhinacanthus nasutus (L.) Kurz, which is native to Thailand and Southeast Asia, has become known for its antioxidant properties. Neuronal loss in a number of diseases including Alzheimer's disease is thought to result, in part, from oxidative stress. Glutamate causes cell death in the mouse hippocampal cell line, HT-22, by unbalancing redox homeostasis, brought about by a reduction in glutathione levels, and amyloid-β has been shown to induce reactive oxygen species (ROS) production. Here in, we show that ethanol extracts of R. nasutus leaf and root are capable of dose dependently attenuating the neuron cell death caused by both glutamate and amyloid-β treatment. We used free radical scavenging assays to measure the extracts antioxidant activities and as well as quantifying phenolic, flavonoid and sterol content. Molecules found in R. nasutus, lupeol, stigmasterol and β-sitosterol are protective against glutamate toxicity.     

Characterization of Aroma-Active Compounds in Iranian cv. Mari Olive Oil by Aroma Extract Dilution Analysis and GC–MS-Olfactometry

Aroma, aroma‐active compounds and fatty acid profiles of Iranian olive oil obtained from the cv. Mari were investigated for the first time in the current study. Aroma extracts were isolated from the oil by using a purge and trap extraction system and their compositions were analyzed by gas chromatography‐mass spectrometry‐olfactometry (GC–MS‐O). A total of 35 aroma compounds comprising alcohols, aldehydes, acids, esters, ketones, terpenes and volatile phenols were identified and quantified in the assayed samples. Aldehydes were present at the highest levels, followed by ketones and alcohols. (E)‐2‐Hexenal was quantitatively (1589 µg kg^?1) the main aroma compound in the analyzed oils, followed by hexanal and (E)‐2‐heptenal. The aroma‐active volatiles were elucidated in the aromatic extract by applying aroma extract dilution analysis (AEDA). The results of AEDA revealed 17 aroma‐active compounds. Under these condition it was possible to completely identify 16 of these compounds. Regarding to the flavor dilution (FD) factor, the most potent odorants with the highest FD factor were (E)‐2‐hexenal (512), followed by hexanal, 6‐methyl‐5‐hepten‐2‐one, (E)‐2‐decenal and one unknown compound (LRI = 1871). The fatty acid profile of the tested oils was composed of thirteen compounds. Oleic acid was the main fatty acid (76.01 %) followed by palmitic acid.     

Phenolic Compounds in a Sahelian Sorghum (Sorghum bicolor) Genotype (CE145–66) and Associated Soils

CE_145–66 is an improved early-maturing grain sorghum genotype, increasingly grown by farmers in the Sahelian part of Senegal. This genotype is known to have negative effects on the following groundnut crop, because of the release of allelopathic phenolic compounds into the soil. We have assessed the synthesis of phenolics in sorghum vegetative parts and the variations in synthesis between years and sites. Total phenols and phenolic acids in the aerial parts and roots of flowering sorghum plants from 52 farmers' fields at two sites (Sagnanème and Médina) in Senegal in 1996 and 1997 were measured. Thirty-eight soil samples, collected after the sorghum harvest, from sorghum rows and interrows also were analyzed for their phenolic content. Total phenols reached 1.1–1.5% of root dry weight and 1.1–2.2% of aerial parts dry weight, with little variation between sites, and large variability between years, presumably due to climatic conditions. Eight phenolic acids and three associated aldehydes were identified by HPLC, with p-hydroxybenzoic, p-coumaric, and ferulic acids the most abundant. Their totals reached 2.9–3.2 mg/g in 1996 and 2.6–2.8 mg/g in 1997 for the aerial part; and 3.3–3.6 mg/g in 1996 and 2.8–3.3 mg/g in 1997 for roots. In soils under sorghum rows, the mean water-soluble total phenols increased from 4.6 in 1997 to 6.7 g/g in 1998 in Sagnanème, and from 3.8 in 1997 to 5 g/g in 1998 in Médina. The concentrations of total phenols and phenolic acids were higher in rows than in interrows. All the phenolic monomers identified in vegetative parts were recovered in associated soil samples, with vanillic and p-hydroxybenzoic acids the most abundant. Finally, variability in plant phenolic content seemed more due to climatic than to cropping or soil factors, as differences between years appear more important than differences between or within sites.     

Copper-Catalyzed α-Arylation of Sulfoxonium Ylides Using Hypervalent Iodine Compounds

A Cu(I)-catalyzed synthesis of α-arylated sulfoxonium ylides has been achieved from mesitylene-derived diaryliodonium salts and α-carbonyl sulfoxonium ylides. The reaction is believed to proceed via an electrophilic Cu(III)-aryl intermediate that can be trapped upon nucleophilic attack of the sulfoxonium ylide precursor. The reaction was tolerant to both α-keto and α-ester-derived sulfoxonium ylides, to drug-derived ylide motifs and to electronically-diverse arenes, and enabled the direct synthesis of 32 α-aryl-sulfoxonium ylides in 42–85% yield.     

R(o)hm Molding Compounds投资DVD设备

2001年5月,一个主要针对消费者的DVD试验工厂在德国的中部城市达姆施塔特开始运转.这个试验工厂是由Business Line R(o)hm Molding Compounds与其合作伙伴--OK Media Disc Service GmbH ＆ Co.KG共同设立的.工厂的"心脏"是Singulus的Spaceline DVD设备,在一定的生产条件下,该设备可以用PLEXIGLAS(R)DQ501来生产DVD5和DVD9.此举的目的一方面是为了论证利用PLEXIGLAS(R)DQ501 PMMA材料进行DVD制造的可行性,同时也是对在现行条件下用于生产未来格式的模塑料的一种开发.