Kinetics of the Reactions of Chlorinated Very Short-Lived Substances (VSLSs) with Chlorine Atoms.

Chlorinated very short-lived substances (VSLSs), which are not controlled by the Montreal Protocol, are of current concern with regard to recovery of stratospheric ozone. Further study is needed on the temperature dependences of chlorinated VSLSs relevant to atmospheric conditions. Here, the kinetics of chlorinated VSLSs, such as chloroform (CHCl3), dichloromethane (CH2Cl2), dichloroethane (CH2ClCH2Cl), and trichloroethene (C2HCl3) reacting with chlorine atoms, were investigated between 180 and 400 K, expanding the range of temperatures relative to previous studies. RRKM/Master Equation and Canonical Variational Transition State Theory were utilized to calculate the rate coefficients using the MultiWell suite of programs. CCSD(T), QCISD(T), and M062X with aug-cc-pV(T+d)Z levels of theory were used to calculate the kinetic parameters. Arrhenius equations obtained from fits to the calculated rate coefficients are k1 = (2.66 ± 0.7) × 10-12 exp [(-927 ± 131)/T] cm3 molecule-1 s-1, k2 = (8.99 ± 0.3) × 10-12 exp [(-957 ± 19)/T] cm3 molecule-1 s-1, k3 = (1.51 ± 0.16) × 10-11 exp [(-714 ± 54)/T] cm3 molecule-1 s-1, and k4 = (9.17 ± 1.8) × 10-12 exp [(612 ± 101)/T] cm3 molecule-1 s-1 for the reactions of CHCl3, CH2Cl2, CH2ClCH2Cl, and C2HCl3 with Cl atoms, respectively. The rate coefficients for the reactions of chlorinated VSLSs with Cl atoms from this study are compared with the most recent recommended values from the NASA/JPL and IUPAC evaluations and with literature values. The reactivity trends of the reactions are discussed.

Capparis zeylanica L. conjugated TiO2 nanoparticles as bio-enhancers for antimicrobial and chronic wound repair.

Chronic, non-healable wounds have been a threat throughout history and have consumed centuries of traditional and modern research. In wound repair, a growing variety of novel treatments have been developed. At various stages of wound healing, nanostructure systems are employed. The drug may be synthesized at the nanoscale to act as a "provider," or nanomaterial could be employed as biomedical devices. Capparis zeylanica was used to synthesize Titanium dioxide nanoparticles (TiO2NPs) under ambient temperature. The UV-Vis spectrophotometer was used to confirm the illumination of fabricated TiO2NPs tuned to a size of 352 nm TiO2NPs have been revealed to be spherical and linked to one another using scanning electron microscopy. Biologically active functionality molecules involved in green synthesized TiO2NPs were indicated by Fourier transform infrared spectroscopy peaks. The TiO2NPs are amorphous, according to X-ray diffraction spectra. Skin diseases causing pathogens were studied for anti-microbial activity using the agar well diffusion method, and the results indicated significant anti-microbial properties. Furthermore, the wound healing ability of fabricated TiO2NPs was investigated in an excision wound model in Swiss albino mice. Finally, our findings revealed that TiO2NPs had provided a unique therapeutic approach for wound healing and in the planning of therapies.

TiO2 nanoparticles derived from egg shell waste: Eco synthesis, characterization, biological and photocatalytic applications.

Biosynthesis of metal oxide nanoparticles has attracted much attention in recent years owing to the increasing impact for improving hygienic substances, cost effective approaches, environment friendly solvents and reusable resources. The present study has shown the eco synthesis of TiO2 nanoparticles using the aqueous extract of egg shell waste. UV, XRD, FT-IR, and FE-SEM with EDX methods were implied for TiO2 nanoparticles. The agar well approach was used to investigate the antimicrobial properties of biosynthesized nanoparticles against pathogenic organisms. The cytotoxicity analysis was investigated by MTT assay method and photocatalytic activity was studied using methylene blue, methyl orange and Congo red dye. X-ray diffraction studies showed that the presence of tetragonal structure. The crystallite size of synthesized TiO2 nanoparticles is 27.3 nm. FE-SEM analysis indicates that the average grain size of the prepared sample was found to be in the range of 30-40 nm. Eco synthesis of TiO2 nanoparticles displayed amazing antimicrobial efficacies against human pathogenic organisms and obtained excellent cytotoxicity investigation was performed against Osteosarcoma cell lines (MG-63). Further it was also found that the expression of impressive catalytic efficiency, 91.1 percent decreased in 60 min for methylene blue. From the results, we found that eco synthesized TiO2 nanoparticles has promising utility in multidisciplinary like antimicrobial, anticancer and photocatalytic applications.

Assessment of spatial-temporal changes in water bodies and its influencing factors using remote sensing and GIS - a model study in the southeast coast of India.

Concerns have been raised about the threat of ecological imbalance due to the loss of water bodies in densely populated areas. The present study explored the changes in water bodies in terms of area, number, and size in northern districts of Tamil Nadu, India, between 1978 and 2018 using satellite data, geographic information system, spatial analysis, ground truth verification, and field validation. The analysis indicated that the water bodies' area has reduced by 3027 ha and 4363 ha in the Kancheepuram and Tiruvallur Districts, respectively. Almost 179 water bodies have entirely disappeared, and 628 water bodies have been partly converted for other purposes. Of the disappeared water bodies, small, medium, and large water bodies account for 53, 93, and 33, respectively. The main reason for the changes in water bodies was the conversion to agriculture and buildings. Overall, the water bodies' area and number have been reduced by 9% and 12%, respectively, while the population has grown by 37%. The water bodies lost due to anthropogenic activities demand the scientific inventory of water bodies and integrated water resources management at a state or national level with strict monitoring regulations to protect them.

King or royal family? Testing for species boundaries in the King Cobra, Ophiophagus hannah (Cantor, 1836), using morphology and multilocus DNA analyses.

In widespread species, the diverse ecological conditions in which the populations occur, and the presence of many potential geographical barriers through their range are expected to have created ample opportunities for the evolution of distinct, often cryptic lineages. In this work, we tested for species boundaries in one such widespread species, the king cobra, Ophiophagus hannah (Cantor, 1836), a largely tropical elapid snake distributed across the Oriental realm. Based on extensive geographical sampling across most of the range of the species, we initially tested for candidate species (CS) using Maximum-Likelihood analysis of mitochondrial genes. We then tested the resulting CS using both morphological data and sequences of three single-copy nuclear genes. We used snapclust to determine the optimal number of clusters in the nuclear dataset, and Bayesian Phylogenetics and Phylogeography (BPP) to test for likely species status. We used non-metric multidimensional scaling (nMDS) analysis for discerning morphological separation. We recovered four independently evolving, geographically separated lineages that we consider Confirmed Candidate Species: (1) Western Ghats lineage; (2) Indo-Chinese lineage (3) Indo-Malayan lineage; (4) Luzon Island lineage, in the Philippine Archipelago. We discuss patterns of lineage divergence, particularly in the context of low morphological divergence, and the conservation implications of recognizing several endemic king cobra lineages.

Experimental and Computational Investigations of the Tropospheric Photooxidation Reactions of 1,1,1,3,3,3-Hexafluoro-2-Methyl-2-Propanol Initiated by OH Radicals and Cl Atoms.

The gas-phase kinetics for the reactions of OH radicals and Cl atoms with 1,1,1,3,3,3-hexafluoro-2-methyl-2-propanol (HF2M2P) were measured at temperatures between 268 and 363 K using the relative rate experimental technique. Methane and acetonitrile were used as reference compounds to measure the rate coefficients of the title reactions. For the reactions of HF2M2P with OH radicals and Cl atoms, the rate coefficients were measured to be (7.07 ± 1.21) × 10-15 and (2.85 ± 0.54) × 10-14 cm3 molecule-1 s-1, respectively, at 298 K. The obtained Arrhenius expressions for the reactions of HF2M2P with OH radicals and Cl atoms are kHF2M2P + OHExp - (268 - 363 K) = (7.84 ± 0.75) × 10-14 exp [-(717 ± 59)/T] and kHF2M2P + ClExp - (268 - 363 K) = (3.21 ± 0.45) × 10-12 exp [-(1395 ± 83)/T] cm3 molecule-1 s-1. In addition to the experimental measurements, computational kinetic calculations were also performed for the title reactions at the M06-2X/MG3S//M06-2X/6-31 + G(d,p) level of theory using advanced methods such as the canonical variational transition-state theory coupled with small curvature tunneling corrections at temperatures between 200 and 400 K. Theoretical calculations reveal that the H-abstraction from the CH3 group is a more favorable reaction channel than that from the OH group. Thermochemistry, branching ratios, cumulative atmospheric lifetime, global warming potential, acidification potential, and photochemical ozone creation potential of HF2M2P were calculated in the present investigation.

Extraction methods and computational approaches for evaluation of antimicrobial compounds from Capparis zeylanica L.

Capparis zeylanica Linn (Caparadaceae), a well-known traditional medicinal plant has been used prevalently in the Ayurvedic system of medicine. It has long been used in treating cholera, hemiplegia, pneumonia, helmintic and inflammatory activity. This study aims to investigate the antimicrobial activity of C. zeylanica leaf extracts against pathogenic microorganisms, with the interactions of potential compounds being predicted by a computational approach. Ethyl acetate leaf extracts of C. zeylanica were evaluated for antimicrobial activity using an agar well diffusion method against pathogenic microorganisms (Staphylococcus epidermidis, Enterococcus faecalis, Salmonella paratyphi, Shigella dysenteriae, Mycobacterium tuberculosis and Candida albicans). The ethyl acetate leaf extracts of the C. zeylanica were utilized for GC-MS analysis. Computational studies were performed to analyze the novel compound using Schrodinger software. The various concentrations of ethyl acetate leaf extract of C. zeylanica were checked against pathogenic microorganisms. Among them, Salmonella paratyphi shows the maximum inhibition. Molecular docking and ADME properties showed that (3E)-N-(3,4 Dichlorophenyl)-3-(Propionylhydrazono) butanamide, Heptadecanoic-Margaric acid and 5-(3-Fluorophenyl)-7-nitro-1,3-dihydro-2H-1,4-benzodiazepine-2-one had the highest fitness score and more specificity toward the microbial receptors.

Water vapor flux in tropical lowland rice.

A field experiment was conducted at Indian Council of Agricultural Research-National Rice Research Institute, Cuttack, Odisha, India in the dry seasons of 2015 and 2016 to assess the water vapor flux (FH2O) and its relationship with other climatic variables. The FH2O and climatic variables were measured by an eddy covariance system and a micrometeorological observatory. Daily mean FH2O during the dry seasons of 2015 and 2016 were 0.009-0.092 g m-2 s-1 and 0.014-0.101 g m-2 s-1, respectively. Seasonal average FH2O was 14.6% higher in 2016 than that in 2015. Diurnal variation for FH2O showed a bell-shaped curve with its peak at 13:30-14:00 Indian Standard Time (IST) in both the years. Carbon dioxide flux was found higher with rise in FH2O. This relationship was stronger at higher vapor pressure deficit (VPD) (20 ≤ VPD ≤ 40 and VPD > 40 hPa). The FH2O showed significant positive correlation with latent heat flux, net radiation flux, photosynthatically active radiation, air, water and soil temperatures, shortwave down and upwell radiations, maximum and minimum temperatures, evaporation, and relative humidity in both the years. Principal component analysis showed that FH2O was very close to latent heat flux in both the years (Pearson correlation coefficient close to 1). The two-dimensional observation map of the principal component F1 and F2 showed the observations taken during the vegetative stage and panicle initiation stage, and flowering stage and maturity stage were closer to each other. It can be concluded that the most important climatic variables controlling the FH2O were latent heat of vaporization, net radiation, air temperature, soil temperatures, and water temperature.

Phytochemical analysis and antimicrobial activity of some medicinal plants against selected pathogenic microorganisms.

The aim of the present study is to investigate the antimicrobial potency of leaves from various extracts of Capparis zeylanica, Streblus asper and Tribulus terrestris were evaluated. In addition, this is the first report on MIC, MBC/MFC antimicrobial activities of above mentioned plants and also identify the phytochemical, functional groups by GC-MS and FT-IR respectively. Soxhlet extraction method was used for preparation of different extracts viz., aqueous, petroleum ether, ethyl acetate and methanol. The extracts were examined against Staphylococcus epidermidis, Enterococcus faecallis, Salmonella paratyphi, Shigella dysenteriae, Candida albicans and Mycobacterium tuberculosis by agar well diffusion method, and Minimum Inhibitory Concentratioon (MIC), Minimum Bactericidal/Fungicidal Concentration (MBC/MFC) values were determined through micro dilution method. Phytochemical analysis of compounds was carried out by GC-MS analysis and functional groups were identified by FT-IR. Based on the outcome of our results, Ethyl acetate extract Showed significant antimicrobial activity against the tested pathogens especially, for C. albicans (40 mm) followed by ethyl acetate of S. asper against S. paratyphi (38 mm). While, the least inhibition was observed with aqueous extract of T. terrestris against S. paratyphi (10 mm). The MIC ranged from 3.21 mg/ml to 50 mg/ml and MBC/MFC 6.25 mg/ml to 50 mg/ml was recorded. Ethyl acetate extracts of almost all samples showed better activity than other extracts in inhibition growth of pathogens. Phytochemical analysis exhibited the presence of Steroids, tannins and cardiac glycosides were found only in ethyl acetate extract of C. zeylanica. Functional group of leaf extract was confirmed by FT-IR spectrum and GC-MS analysis of the ethyl acetate extract revealed the presence of 20 compounds. The results revealed that ethyl acetate extract of C. zeylanica leaves has potential activity than the other extracts as well as standard drugs (Gentamycin and Ketocozole). Hence, this plant may be recommended for further studies in isolation of active compounds and related pharmacological activities.

Identification and isolation of antimicrobial compounds from the flower extract of Hibiscus rosa-sinensis L: In silico and in vitro approaches.

The modern people are preparing the natural medicines from the plants and their parts for curing various diseases. The present study was chosen Hibiscus rosa-sinensis flowers to analyze its antimicrobial capabilities against venereal diseases causing pathogens. In this study, the antimicrobial activity performed in different solvents prepared flower extracts using agar well diffusion method. Among the extracts, the methanolic flower extract of Hibiscus rosa-sinensis shows better results than other solvents extracts. The extract analysed by GC-MS which was exposes seven bioactive molecules. These bioactive molecules were docked with N. gonorrhoea protein. Finally, benzene dicarboxylic acid had best glide docking XP scores -7.955 with better binding energy values (-38.692 kcal/mol) than other ligand molecules. Hence, this molecule was isolated from the flowers of H. rosa-sinensis. After that, the different concentrations of 1,2 benzene dicarboxylic acid were tested on human diseases causing microbial strains. There, all the levels were showed good anti-gonorrhoeal activity against N. gonorrhoeae. Hence this study suggested that 1,2 benzene dicarboxylic acid could be used as a better drug candidate for venereal diseases.

Biosynthesis, characterization and antimicrobial activities of zinc oxide nanoparticles from leaf extract of Glycosmis pentaphylla (Retz.) DC.

Biosynthesized nanoparticles have an incredible application in biomedicine owing to its simplicity, eco-friendly properties and low cost. The present study aims to determine the green synthesized zinc oxide nanoparticles from methanolic leaf extract of Glycosmis pentaphylla. The synthesized nanoparticles were characterized using UV-VIS Spectroscopy, Fluorescence spectrometer, FT-IR, XRD, SEM with EDAX and TEM. The confirmations of synthesized nanoparticles were characterized by peak at 351 and 410 nm in the UV-VIS spectrum and photoluminescence spectrum respectively. FT-IR studies revealed the functional group of the nanoparticles. The XRD data showed the crystalline nature of the nanoparticles and EDAX measurements indicated the 20.70% of highly pure zinc oxide metal. The morphological characterization of synthesized zinc oxide nanoparticles was analyzed by SEM and TEM and size of the particles were ranging from 32 to 36 nm. The synthesized zinc oxide nanoparticles exhibited interesting antimicrobial activity against pathogenic organisms. In addition, this is the first report on leaf mediated synthesis of zinc oxide (ZnO) nanoparticles from Glycosmis pentaphylla.

Effect of microencapsulated probiotic Bacillus vireti 01-polysaccharide extract of Gracilaria folifera with alginate-chitosan on immunity, antioxidant activity and disease resistance of Macrobrachium rosenbergii against Aeromonas hydrophila infection.

Polysaccharide from red seaweed Gracilaria folifera has an interesting functional property of antioxidant activity and prebiotic effect. A feeding trial experiment was directed to examine the effect of probiotic bacteria Bacillus vireti 01 microencapsulated with G. folifera polysaccharide against freshwater prawn M. rosenbergii. Three different feeding trials were conducted for 15 days. The first group contained prawns fed with commercial diet. The second group was comprised of Aeromonas hydrophila challenged prawns fed with commercial feed. The third group consisted of A. hydrophila challenged prawns fed with microencapsulated probiotic-polysaccharide. Survival percentage was significantly decreased in prawns of group2 as compared to that of group1 and group3 prawns (p < 0.0001). The immunological parameters and antioxidant activities (p < 0.001) were found to be increased in group three prawns which were fed with encapsulated probiotic-seaweed polysaccharide and challenged with A. hydrophila as compared to that of group1 and group2. Tissue necrosis, fused lamella, haemocyte infiltration and damage of hepatopancreas lumen and tubule were noted in group2 prawns. There was no histological changes were observed in group3 prawns in which the histological architecture was similar to the control group1. The results suggested that combination of encapsulated probiotic B. vireti 01 and seaweed polysaccharide as dietary feed showed an enhancement of immune response, antioxidant activity and disease resistant of M. rosenbergii against A. hydrophila.

Green synthesis of silver nano particles from Atalantia monophylla (L) Correa leaf extract, their antimicrobial activity and sensing capability of H2O2.

In the present study deals with the green synthesis of silver nano particles from methanolic leaf extracts of Atalantia monophylla. The synthesized nano-particles are characterized by UV-vis spectroscopy, PL, FTIR, XRD, SEM with EDAX and TEM. The nano-particles are indicated in absorption peak at 404 nm in the absorption spectrum. Further micro graphical analysis confirmed the average size was estimated about 35 nm and SEAD pattern authorized well crystalline materials. The FTIR studies help to confirm the functional group of synthesized silver nano particles. The XRD data shown the crystalline nature of nano particles and EDAX measurement indicates the purity of silver metal. The antimicrobial effect of silver nanoparticles was tested on pathogenic organisms using agar well diffusion method. Minimum inhibitory concentration (MIC) and Minimum bactericidal/fungicidal concentration (MBC/MFC) were also investigated in different concentrations of leaf extract. The results indicated that synthesized silver nano particle of A. monophylla leaf extract has the potential of antimicrobial activity against pathogenic microorganism. In addition, this is the first report on leaf synthesized silver nano particles of A. monophylla. The antimicrobial activity against pathogenic microorganisms and the ability to detect hydrogen peroxide using the silver nanoparticles were confirmed which would find applications in the development of new antimicrobial drugs and new biosensors to detect the presence of hydrogen peroxide in various samples respectively.

Therapeutic effects of gold nanoparticles synthesized using Musa paradisiaca peel extract against multiple antibiotic resistant Enterococcus faecalis biofilms and human lung cancer cells (A549).

Botanical-mediated synthesis of nanomaterials is currently emerging as a cheap and eco-friendly nanotechnology, since it does not involve the use of toxic chemicals. In the present study, we focused on the synthesis of gold nanoparticles using the aqueous peel extract of Musa paradisiaca (MPPE-AuNPs) following a facile and cheap fabrication process. The green synthesized MPPE-AuNPs were bio-physically characterized by UV-Vis spectroscopy, FTIR, XRD, TEM, Zeta potential analysis and EDX. MPPE-AuNPs were crystalline in nature, spherical to triangular in shape, with particle size ranging within 50 nm. The biofilm inhibition activity of MPPE-AuNPs was higher against multiple antibiotic resistant (MARS) Gram-positive Enterococcus faecalis. Light and confocal laser scanning microscopic observations evidenced that the MPPE-AuNPs effectively inhibited the biofilm of E. faecalis when tested at 100 µg mL-1. Cytotoxicity studies demonstrated that MPPE-AuNPs were effective in inhibiting the viability of human A549 lung cancer cells at higher concentrations of 100 µg mL-1. The morphological changes in the MPPE-AuNPs treated A549 lung cancer cells were visualized under phase-contrast microscopy. Furthermore, the ecotoxicity of MPPE-AuNPs on the freshwater micro crustacean Ceriodaphnia cornuta were evaluated. Notably, no mortality was recorded in MPPE-AuNPs treated C. cornuta at 250 µg mL-1. This study concludes that MPPE-AuNPs are non-toxic, eco-friendly and act as a multipurpose potential biomaterial for biomedical applications.

Experimental and Theoretical Investigations on the Reaction of 1,3-Butadiene with Cl Atom in the Gas Phase.

Temperature dependent rate coefficients for the reaction of Cl atom with 1,3-butadiene were measured over the temperature range 269-363 K relative to its reaction with isoprene and 1-pentene. Theoretical calculations were performed for the title reaction using CVT/SCT in combination with CCSD(T)/6-31+G (d,p)//MP2/6-311+G(2df,2p) level of theory, to complement our experimental measurements. The test molecule would survive for 1 h in the atmosphere, and therefore, it can be considered as a very short-lived compound. 1,3-Butadience cannot contribute to global warming as it is very short-lived. However, 4 ppm of ozone is estimated to be formed by the test molecule, which can be considered to be reasonably significant.

An Exprimental and Computational Study on the Cl Atom Initiated Photo-Oxidization Reactions of Butenes in the Gas Phase.

Temperature-dependent rate coefficients for the reactions of Cl atoms with trans-2-butene and isobutene were measured over the temperature range of 263-363 K using relative rate technique with reference to 1,3-butadiene, isoprene, and 1-pentene. The measured rate coefficients for the reactions of Cl atoms with isobutene and trans-2-butene are kR1298K= (3.43 ± 0.11) × 10-10 and kR2298K = (3.20 ± 0.04) × 10-10 cm3 molecule-1 s-1, respectively, at 298 K and 760 torr. Measured rate coefficients were used to fit the Arrhenius equations, which are obtained to be kR1-Exp269-363K = (4.99 ± 0.42) × 10-11 exp[(584 ± 26)/T] and kR2-Exp269-363K = (1.11 ± 0.3) × 10-10 exp[(291 ± 88)/T] cm3 molecule-1 s-1 for isobutene and trans-2-butene, respectively. To understand the reaction mechanism, estimate the contribution of each reaction site, and to complement our experimental results, computational studies were also performed. Canonical variational transition state theory with small curvature tunneling in combination with MP2/6-31G(d), MP2/6-31G(d,p), MP2/6-31+G(d,p), CCSD(T)/cc-pvdz, and QCISD(T)/cc-pvdz level of theories were used to calculate the temperature-dependent rate coefficients over the temperature range of 200-400 K. The effective lifetimes, thermodynamic parameters, and atmospheric implications of the test molecules were also estimated.

Glaciations, gradients, and geography: multiple drivers of diversification of bush frogs in the Western Ghats Escarpment.

The historical processes underlying high diversity in tropical biodiversity hotspots like the Western Ghats of Peninsular India remain poorly understood. We sampled bush frogs on 13 massifs across the Western Ghats Escarpment and examined the relative influence of Quaternary glaciations, ecological gradients and geological processes on the spatial patterns of lineage and clade diversification. The results reveal a large in situ radiation (more than 60 lineages), exhibiting geographical structure and clade-level endemism, with two deeply divergent sister clades, North and South, highlighting the biogeographic significance of an ancient valley, the Palghat Gap. A majority of the bush frog sister lineages were isolated on adjacent massifs, and signatures of range stasis provide support for the dominance of geological processes in allopatric speciation. In situ diversification events within the montane zones (more than 1800 m) of the two highest massifs suggest a role for climate-mediated forest-grassland persistence. Independent transitions along elevational gradients among sub-clades during the Miocene point to diversification along the elevational gradient. The study highlights the evolutionary significance of massifs in the Western Ghats with the high elevations acting as centres of lineage diversification and the low- and mid-elevations of the southern regions, with deeply divergent lineages, serving as museums.

Is H Atom Abstraction Important in the Reaction of Cl with 1-Alkenes?

The relative yields of products of the reaction of Cl atoms with 1-alkenes (C4-C9) were determined to see whether H atom abstraction is an important channel and if it is to identify the preferred position of abstraction. The presence of all the possible positional isomers of long chain alkenones and alkenols among the products, along with chloroketones and chloroalcohols, confirms the occurrence of H atom abstraction. A consistent pattern of distribution of abstraction products is observed with oxidation at C4 (next to allyl) being the lowest and that at CH2 groups away from the double bond being the highest. This contradicts with the higher stability of allyl (C3) radical. For a better understanding of the relative reactivity, ab initio calculations at MP2/6-311+G (d,p) level of theory are carried out in the case of 1-heptene. The total rate coefficient, calculated using conventional transition state theory, was found to be in good agreement with the experimental value at room temperature. The preferred position of Cl atom addition is predicted to be the terminal carbon atom, which matches with the experimental observation, whereas the rate coefficients calculated for individual channels of H atom abstraction do not explain the observed pattern of products. The distribution of abstraction products except at C4 is found to be better explained by reported structure activity relationship, developed from experimental rate coefficient data. This implies the reactions to be kinetically dictated and emphasizes the importance of secondary reactions.

Quality characteristics and plasmin activity of thermosonicated skim milk and cream.

The shelf life of pasteurized milk is limited by heat-stable proteases, which cause gelation and bitter taste upon extended storage of milk. Ultra-high temperature processing inactivates proteases but detrimentally affects milk's sensory quality. An adjunct to pasteurization is desired to extend milk's shelf life while maintaining quality characteristics. In this study, the effects of combined heat and ultrasound (thermosonication) on total plasmin activity and various quality characteristics of skim milk and cream were studied. Thermosonication, at an average power of 115 W (152 µmp-p, where p-p=peak-to-peak amplitude) for 3 min, decreased the total plasmin activity (i.e., plasmin- and plasminogen-derived activity) by nearly 94% in fresh skim milk and cream. Enzyme activity in thermosonicated skim milk samples measured at the end of 30 d was 5- to 10-fold higher than on d 0, but remained stable in thermosonicated cream. Descriptive analysis of odor attributes was conducted for up to 4 wk with 8 trained panelists. No significant differences were observed between the intensities of offensive "eggy" and "rubbery" odor attributes of thermosonicated skim milk and pasteurized commercial skim milk and cream. In addition, lightness (L*) values and viscosity were not adversely affected by thermosonication. Thermosonication decreased the fat globule size in skim milk and cream, and the homogenizing effect increased with treatment time. Thermosonication at average powers of 104 W (133 µmp-p) and 115 W (152 µmp-p) for 1 and 3 min destroyed coliforms and over 99% of the total aerobic bacteria. The total aerobic bacteria counts of thermosonicated skim milk and cream samples were less than 20,000 cfu/mL on d 30. Because thermosonication did not induce off-aromas or viscosity changes but did inactivate microorganisms and protease enzymes, thermosonication may be an appropriate adjunct to pasteurization to extend milk shelf life.