Carbon Chain Compounds Research Articles

Alumina-supported multi-metal catalyst for e-waste management for reclamation of valuable products

ABSTRACT Electronic and electrical waste (e-waste) has increased exponentially due to the humungous growth in the information technology and communication sector. Many multi-metal catalysts are developed by researchers for electronic waste plastic conversion into fuel products and recovery of valuable metals. In the present study, an Alumina-supported catalyst powder with selected transition metals metal oxides was prepared to improve the yield of hydrocarbon liquids. FESEM with energy-dispersive spectroscopy, XRD and laser diffraction particle size analysis were used to characterise catalysts. The shredded e-waste chips to catalyst weight ratio was maintained from 2:1 to 10:1 and studied. The experiments were conducted with a reaction temperature range from 300°C to 500°C. The produced fuel density was 0.88 kg/L, with 0.75 liquid fuel conversion and 71.7% overall liquid fuel yield. The light gas percentage was 4–6%. NMR analysis, bomb calorimetric study and gas chromatography-mass spectroscopy of liquid fuel analysis suggest carbon chain compounds of C3–C20 hydrocarbon, indicating a mixture of petrol and diesel-like liquid products. The catalyst can be tuned to improve liquid fuel conversion. The liquid fuel product is promising for fuel use, however, upgrading treatments are needed to meet standard product specifications.

Analysis of bio-oil production and characterization from duckweed biomass

In this study, the production and characterization of bio-oil from duckweed was carried out through a pyrolysis process. The study aim is to produce and characterize bio-oil from duckweed through a pyrolysis process. The method used in the production of bio-oil from duckweed in this study is the pyrolysis method where a fix-bed reactor was connected to a condensers and heat was applied from a gas burner and the temperature was monitored using a thermocouple connected to the reactor and time monitored by a stopwatch until the last drop of product was observed from the system. Analysis of produced bio-oil shows that it is a heavy oil with API gravity of ˚8.73, density value of 1.006 g/cm3 at 22 oC, specific gravity of 1.009 kg/m3 and a high viscosity of 9.32 mm2.s-1. Further analysis resulted in a high flashpoint of 93 oC and a pour point of 14 oC respectively. GC/MS analysis carried out on the bio-oil sample shows that it contains Polyaromatic hydrocarbon (PaH) at different concentrations. The study also showed that the produced bio-oil contains carbon chain compounds; C8-C28. It was concluded that bio-oil produced from duckweed is a potential green alternative to fossil fuels and efforts should be made by relevant bodies to convert the laboratory scale production of duckweed to industrial scale as it will be a good and possible alternative for fossil fuel.

Analysis on Electrochemical CO2 Reduction by Diamond Doping Technology

Abstract Mitigating the massive emissions of greenhouse gases is one of the main measures taken to resolve the current growing climate problems. The electrochemical reduction of carbon dioxide to economically valuable chemical fuels has attracted the intensive attention of scholars. This review provides an overview of the application of conductive diamond in electrocatalytic reduction and outlines the improvement of electrochemical properties by employing metal particles to modify the surface. Meanwhile, the carbon-based electrode materials represented by glassy carbon and diamond-like carbon also have broad research value. Emphasis is placed on the electrochemical properties of boron-doped, transition metal modification, and co-doped diamond film electrodes with appropriate extensions. The carbon-chain compounds produced by the reduction reaction are also briefly described, mainly using formic acid and ethanol as examples, and focusing on the switchable selectivity of the multi-carbon products. In addition, the development directions of electrochemical reduction technology are prospected.

Methanethiol Consumption and Hydrogen Sulfide Production by the Thermoacidophilic Methanotroph Methylacidiphilum fumariolicum SolV.

Methanotrophs aerobically oxidize methane to carbon dioxide to make a living and are known to degrade various other short chain carbon compounds as well. Volatile organic sulfur compounds such as methanethiol (CH3SH) are important intermediates in the sulfur cycle. Although volatile organic sulfur compounds co-occur with methane in various environments, little is known about how these compounds affect methanotrophy. The enzyme methanethiol oxidase catalyzing the oxidation of methanethiol has been known for decades, but only recently the mtoX gene encoding this enzyme was identified in a methylotrophic bacterium. The presence of a homologous gene in verrucomicrobial methanotrophs prompted us to examine how methanotrophs cope with methanethiol. Here, we show that the verrucomicrobial methanotroph Methylacidiphilum fumariolicum SolV consumes methanethiol and produces H2S, which is concurrently oxidized. Consumption of methanethiol is required since methanethiol inhibits methane oxidation. Cells incubated with ∼15 μM methanethiol from the start clearly showed inhibition of growth. After depletion of methanethiol, growth resumed within 1 day. Genes encoding a putative methanethiol oxidase were found in a variety of methanotrophs. Therefore, we hypothesize that methanethiol degradation is a widespread detoxification mechanism in methanotrophs in a range of environments.

Enhancement of antidermatophytic activities of Citrullus colocynthis Schrad collected from different ecological habitats in Egypt using fluconazole

BackgroundDermatophytes may cause various and severe types of fungal infections in several communities. Herbal plant extracts may be inhibitory against cutaneous fungi related to Epidermophyton, Microsporum, and Trichophyton. The extract may be more efficient by its mixing with a low concentration of the antifungal agent. PurposeThis study demonstrates the antidermatophytic activities of seed methanol extract of Citrullus colocynthis from different habitats in Egypt, namely Sinai desert, El-Wadi El-Gadid, and Wadi Qena. MethodsA broth microdilution assay was used to determine the MIC and MFC of the extracts against the investigated fungal strains according to the Clinical and Laboratory Standards Institute (CLSI) M38-Ed3 guidelines. GC/MS was employed for the identification of the active constituents. Keratinase, lipase, phospholipase, and protease were measured spectrophotometrically or by determining the diameter of the reaction zone according to standard methods using a specific medium. ResultsC.colocynthis seed methanol extract from Sinai desert combined with 0.5 μg/ml of the antifungal drug fluconazole (FLU) was more effective than the extract or FLU, each on its own, in decreasing spore viability and reduction of fungal enzyme activities. The phytochemical analyses of the methanolic seed extract of the three cultivars show the presence of three common main compounds, namely, (9Z,12Z)-methyl octadeca-9,12-dienoate, (9Z,12E)-methyl octadeca-9,12-dienoate, and (9E,12E)-methyl octdeca-9,12-dienoate. The in-silico docking activity of the main compounds toward fungal enzymes showed a high binding affinity between the first compound and lipase enzymes of Microsporum canis and Trichophyton mentagrophytes. ConclusionsThe variation in the bioactivity of the plant extracts of a certain species may be varied due to the difference of the active constituents that are formed under specific conditions or stress. The inhibitory action of the extract to a certain pathogen could be improved when combined with lower drug concentration. Longer chain carbon compounds were frequently detected in the cultivar of Sinai compared to the compounds identified from the other localities suggesting that there was a variation in the active constituents according to the surveyed habitat although the main core of the constituents is maintained.

Photocatalytic oxidation mechanism of Gas-Phase VOCs: Unveiling the role of holes, •OH and •O2−

To identify the distinctive role of reactive oxygen species (ROS) and trace the intermediates not only help to decompose the pollutants in high efficiency but also for avoiding more harmful intermediates formed. Here, we developed a new method to generate different ROSs by controlling the atmosphere to distinguish their role in the degradation of flowing gas-phase VOCs, including o-xylene, styrene, and acetaldehyde. This method is in good agreement with the traditional sacrificial agent capture experiment. The results show that •OH radicals play a dominant role in the degradation of o-xylene and styrene, while •O2− radicals primarily take part in the acetaldehyde degradation. Additionally, we distinguish the role of holes, •OH and •O2− played during the VOCs photo-oxidation through the radical trapping, in situ DRIFTS, and GC-MS analysis. Under the attack of •O2− radicals, aromatic VOCs were photo-oxidized to intermediates containing benzene rings and ketones (i.e., toluene and butanone), while carbon chain compounds (i.e., 3-methylfuran and ethanol) tend to form under the action of •OH and holes. This can be associated with the different reaction paths initiated by ROS. For acetaldehyde removal, •O2− species facilitate the formation of acids (i.e., acetic acid) while the •OH species and holes lead to the production of ketones (i.e., acetone). This work provides deep understanding on the role of various ROS in the photocatalytic oxidation of VOCs, which can guide the design of efficient photocatalysts, selective formation of intermediates to be easily decomposed or as raw materials for further application.

Synthesis of long chain alkanes via aldol condensation over modified chitosan catalyst and subsequent hydrodeoxygenation

In this paper, jet fuel range alkanes were produced by aldol condensation of furfural and levulinic acid over modified chitosan catalyst and subsequent hydrodeoxygenation. NaOH modified chitosan was developed and used as a solid catalyst in the aldol condensation of furfural and levulinic acid to produce long carbon chain compounds. At room temperature, the total yield of condensation products reached 94.4% over NaOH/CT-4 catalyst. The amine of chitosan plays an important role in the aldol condensation, which reacted with the aldehyde group of the furfural, producing an intermediate Schiff base and promoting the formation of condensation products. This new route avoided the occurrence of side reactions caused by NaOH. Therefore, the yield of the products was greatly increased. Moreover, kinetic analysis of the condensation reaction and the test of catalyst repeatability were also conducted with NaOH/CT-4. The condensation products were further converted to long-chain branched alkanes by hydrodeoxygenation over the 5 wt% Pd/NbOPO4 catalyst. As a potential application, these alkanes could be mixed with and used as the components of jet fuels.

Characterization and Impact of Waste Plastic Oil in a Variable Compression Ratio Diesel Engine

The characterization of pyrolysis oil obtained from mixed waste plastics and its utilization in a compression ignition engine were investigated. The chemical compositions and physicochemical properties of distilled waste plastic oil (WPO) and crude waste plastic oil (CWPO) were analyzed. The experiment was conducted with a variable compression ratio diesel engine at various loads and compression ratios to evaluate combustion characteristics, exhaust emissions, and engine performance. The experimental results show that CWPO contains the highest percentage of carbon atoms in the C4–C11 group, while WPO contains the highest percentage of carbon atoms in the C12–C20 group, similar to the main compositions of diesel fuel. According to the preliminary study in chemical compositions and physicochemical properties, WPO and diesel fuel were selected for the engine test at different compression ratios of 16, 17, and 18 and different engine operating loads of 25%, 50%, and 75% of maximum engine torque at an engine speed of 1500 rpm. It was found that increasing the engine operating load and the compression ratio tends to increase the brake thermal efficiency. Increasing the compression ratio results in a significantly shorter delay time in a combustion state. A lower cetane index and a higher percentage of long chain carbon compounds (C12–C20) could be the main factors affecting higher NOx, CO, and HC emissions with the combustion characteristics of WPO, compared to diesel fuel. The disadvantage of emissions by the use of WPO can be alleviated when the engine is running at maximum load and a high compression ratio.

Azadirachtin directly or indirectly affects the abundance of intestinal flora of Spodoptera litura and the energy conversion of intestinal contents mediates the energy balance of intestine-brain axis, and along with decreased expression CREB in the brain neurons

Azadirachtin is a good growth inhibitor for Lepidopteran larvae, but its effect on the brain neurons, intestinal flora and intestinal contents caused by the growth inhibition mechanism has not been reported yet. This study explored the mechanism of azadirachtin on the growth and development of Spodoptera litura larvae and brain neurons through three aspects: intestinal pathology observation, intestinal flora sequencing, and intestinal content analysis. The results showed that the treatment of azadirachtin led to the pathological changes in the structure of the midgut and the goblet cells in the intestinal wall cells to undergo apoptosis. Changes in the host environment of the intestinal flora lead to changes in the abundance value of the intestinal flora, showing an increase in the abundance value of harmful bacteria such as Sphingomonas and Enterococcus, as well as an increase in the abundance value of excellent flora such as Lactobacillus and Bifidobacterium. Changes in the abundance of intestinal flora will result in changes in intestinal contents and metabolites. The test results show that after azadirachtin treatment, the alkane compounds in the intestinal contents of the larvae are greatly reduced, and the number of the long carbon chain and multi-branched hydrocarbon compounds is increased, unsaturated fatty acids, silicon‑oxygen compounds and ethers. The production of similar substances indicates that azadirachtin has an inhibitory effect on digestive enzymes in the intestines, which results in the inhibition of substance absorption and energy transmission, and ultimately the inhibition of larval growth and brain neurons.

Physiological Perspectives on the Use of Triheptanoin as Anaplerotic Therapy for Long Chain Fatty Acid Oxidation Disorders.

Inborn errors of mitochondrial fatty acid oxidation (FAO) comprise the most common group of disorders identified through expanded newborn screening mandated in all 50 states in the United States, affecting 1:10,000 newborns. While some of the morbidity in FAO disorders (FAODs) can be reduced if identified through screening, a significant gap remains between the ability to diagnose these disorders and the ability to treat them. At least 25 enzymes and specific transport proteins are responsible for carrying out the steps of mitochondrial fatty acid metabolism, with at least 22 associated genetic disorders. Common symptoms in long chain FAODs (LC-FAODs) in the first week of life include cardiac arrhythmias, hypoglycemia, and sudden death. Symptoms later in infancy and early childhood may relate to the liver or cardiac or skeletal muscle dysfunction, and include fasting or stress-related hypoketotic hypoglycemia or Reye-like syndrome, conduction abnormalities, arrhythmias, dilated or hypertrophic cardiomyopathy, and muscle weakness or fasting- and exercise-induced rhabdomyolysis. In adolescent or adult-onset disease, muscular symptoms, including rhabdomyolysis, and cardiomyopathy predominate. Unfortunately, progress in developing better therapeutic strategies has been slow and incremental. Supplementation with medium chain triglyceride (MCT; most often a mixture of C8–12 fatty acids containing triglycerides) oil provides a fat source that can be utilized by patients with long chain defects, but does not eliminate symptoms. Three mitochondrial metabolic pathways are required for efficient energy production in eukaryotic cells: oxidative phosphorylation (OXPHOS), FAO, and the tricarboxylic (TCA) cycle, also called the Krebs cycle. Cell and mouse studies have identified a deficiency in TCA cycle intermediates in LC-FAODs, thought to be due to a depletion of odd chain carbon compounds in patients treated with a predominantly MCT fat source. Triheptanoin (triheptanoyl glycerol; UX007, Ultragenyx Pharmaceuticals) is chemically composed of three heptanoate (seven carbon fatty acid) molecules linked to glycerol through ester bonds that has the potential to replete TCA cycle intermediates through production of both acetyl-CoA and propionyl-CoA through medium chain FAO. Compassionate use, retrospective, and recently completed prospective studies demonstrate significant reduction of hypoglycemic events and improved cardiac function in LC-FAOD patients, but a less dramatic effect on muscle symptoms.

A realistic skeletal mechanism for the oxidation of biodiesel surrogate composed of long carbon chain and polyunsaturated compounds

To obtain a realistic reduced reaction model for the combustion of biodiesel in compression ignition engine, the heavy methyl esters with long carbon chain and polyunsaturated degree were used to characterize real biodiesel fuel in this study. Methyl palmitate (MHD), methyl stearate (MOD), methyl linoleate (MOD9D12D), methyl–5–decenoate (MD5D) and n–decane were selected as the surrogate of biodiesel. A skeletal mechanism with 187 species and 982 reactions was developed for the oxidation of biodiesel surrogate using the decoupling methodology. The mechanism was partitioned into three, including the relatively simplified fuel–related sub-mechanism, the ester group–related sub–mechanism, and the detailed core sub–mechanism during the construction process. It was validated by zero–dimensional ignition delay for each component in biodiesel surrogate under variable conditions. The predicted outcomes are in concordance with the experimental information, which preliminarily verifies the effectiveness and accuracy of the mechanism. A three–dimensional computational fluid dynamics code coupled with the mechanism was subsequently utilized to simulate engine combustion. The findings show that the combustion characteristics of biodiesel are robustly replicated, portraying that the newly developed biodiesel mechanism can be assuredly used in the practical engine simulation.

Comparison of zebrafish in vitro and in vivo developmental toxicity assessments of perfluoroalkyl acids (PFAAs)

ABSTRACT Perfluoroalkyl acids (PFAAs) are persistent environmental contaminants that are associated with various adverse health outcomes. Perfluorooctanoic acid (PFOA) is one of the most prominently detected PFAAs in the environment, which is now replaced with shorter chain carbon compounds including perfluorohexanoic acid (PFHxA) and perfluorobutyric acid (PFBA). The aim of this study was to compare the toxicity of four PFAAs as a function of chain length and head group (carboxylate versus sulfonate) with in vitro and in vivo zebrafish assessments, which were subsequently compared to other cell and aquatic models. Mortality rate increased with chain length (PFOA > PFHxA ≫ PFBA) in both whole embryo/larvae and embryonic cell models. The sulfonate group enhanced toxicity with perfluorobutane sulfonate (PFBS) showing higher toxicity than PFBA and PFHxA in both larvae and cells. Toxicity trends were similar among different aquatic models, but sensitivities varied. Discrepancies with other zebrafish studies were confirmed to be associated with a lack of neutralization of acidic pH of dosing solutions in these other investigations, demonstrating the need for rigor in reporting pH of exposure solutions in all experiments. The zebrafish embryonic cell line was also found to be similar to most other cell lines regardless of exposure length. Overall, results agree with findings in other cell lines and organisms where longer chain length and sulfonate group increase toxicity, except in investigations not neutralizing the exposure solutions for these acidic compounds.

Characterisation of pyrolysis kinetics and detailed gas species formations of engineering polymers via reactive molecular dynamics (ReaxFF)

One of the major limiting factors in fire modelling involving solid pyrolysis of polymer materials is the fundamental understanding of thermal degradation process from solid fuel to gas volatiles. This also brings along other challenges such as the characterisation of the parent combustion fuel in the gas-phase chemical reaction process. To bridge the knowledge gap, this article proposes a methodology applying molecular dynamics (MD) simulation as a tool to characterise the thermal degradation process of polymer composites, especially the emission of volatile and toxic gas species. The method was applied to three common engineering polymers: i) high-density polyethene (HDPE), ii) polymethyl methacrylate (PMMA), and iii) high-impact polystyrene (HIPS). Based on the modelling results, the chemical distribution of the fully-decomposed chemical compounds was realised for the selected polymers. The chemical composition and charring kinetics were validated against thermogravimetry data via experimental measurement. Numerical simulations demonstrated good agreement with the thermogravimetric analysis experiments. It was found that all HDPE, PMMA, and HIPS formed fuel gas with alkane group (i.e. mainly C1-C3) that acted as the combustible source. Furthermore, the composition of char formations for the selective polymers can be predicted by the MD simulation through analysing the accumulation of pure carbon chain compounds. In this study, MD simulation identified the detailed decomposition process from solid to gas phases, which could further act as the precursors of combustible fuel gases in combustion models, and significantly enhance the reliability of toxic gas, charring, and smoke particulate predictions.

Structure Determination, Chemical Synthesis, and Evaluation of Biological Activity of Super Carbon Chain Natural Products

Abstract Marine microorganisms are known to produce natural products, so called super carbon chain compounds whose molecular weights (MWs) exceed one thousand, such as amphidinol 3 (AM3) and maitotoxin (MTX). AM3 (MW 1328) is a long linear compound containing polyol, bis-tetrahydopyran, and polyene moieties, and elicits potent antifungal activities. During the course of our studies on AM3, originally proposed absolute configuration was revised by the chemical synthesis of partial structures in combination with degradation of the natural product. Furthermore, the first total synthesis of AM3 has been achieved based on the convergent method via three components coupling. In addition, we have succeeded in design and synthesis of an artificial truncated analog of AM3 which elicits comparable antifungal activity with those of the natural product. On the other hand, MTX (MW 3422) is a ladder-shaped polyether comprised of thirty-two cyclic ethers, and it elicits potent Ca2+ influx activity. During the course of our structure-activity relationship studies of MTX, we have developed three methods for synthesizing ladder-shaped polyethers via two-ring construction through the coupling of two fragments. The synthetic partial structures corresponding to the hydrophobic parts of MTX inhibited the Ca2+ influx induced by MTX.

Degradation mechanism of perfluorooctanoic acid (PFOA) during electrocoagulation using Fe electrode

In this study, the electrocoagulation of perfluorooctanoic acid (PFOA) in water using an iron (Fe) electrode was investigated. The effects of the current density, stirring speed, and electrolyte concentration (NaCl) on the corresponding removal rates of PFOA were examined. An increase in the current density from 2.4 to 80.0 mA cm−2 led to a significant increase in the removal efficiency of PFOA from 10.0 to 100.0% within 6 h. Formate (HCOO−) ions and three shorter-chain perfluorocarboxylates (i.e., perfluoropentanoic acid; PFPeA, perfluorohexanoic acid; PFHxA, and perfluoroheptanoic acid; PFHpA) were observed as organic byproducts during the electrocoagulation of PFOA, indicating that the C-C bond between C7F15 was first broken down and then was degraded into short carbon-chain compounds by PFOA decomposition. 65% of fluorine recovery as fluoride ions and organic fluorine in shorter-chain byproducts (PFPeA, PFHxA, and PFHpA) with 60% of total organic carbon (TOC) removal was achieved within 6 h during electrocoagulation, while the complete removal of PFOA was achieved. Our results imply that electrocoagulation using Fe electrode can effectively degrade PFOA into shorter-chain byproducts with significant mineralization.

Biosorption of Metal Ions on Methanol Dehydrogenase Enzymatic Activity of Bradyrhizobium japonicum USDA110

This research aims to understand the effect of metal ions bioabsorption which belong on different elemental groups to the methanol dehydrogenase (MDH) enzymatic activity in nitrogen-fixing bacteria Bradyhizobium japonicum USDA 110. Ten metal ions with each have 30μM concentration were added to grow Bradyhizobium japonicum USDA 110 in 10-1 diluted nutrient medium. The MDH activity test showed a similar result between the bacteria grown in medium without metal ions addition (control) and the bacteria were grown in a calcium ion/Ca2+ added media. The highest MDH enzymatic activity was shown on the bacteria grown in a magnesium/Mg2+ added medium, which showed 0.08 (U/mg) enzymatic activities. The addition of magnesium/Mg2+ metal ion accelerates the bacterial growth by 2.6 times and MDH activity by 1.28 times compared to control. The MDH enzyme is essential, especially for bacteria which exist in the soil environment, to adapt to high methanol concentration and to support bacterial anaerobic growth capacity along with plant symbiotic process. Moreover, the MDH activity staining method could also act as pollutant indicators like metal ions and hydrocarbon derivates. This research concluded that metal ions biosorption (calcium/Ca2+ and magnesium/Mg2+) are required for bacterial cells reproduction and oxidation of single carbon chain compounds like methanol. The nitrogen-fixing symbiotic bacteria, Bradyhizobium japonicum USDA 110 showed high MDH activity after the two metal ions absorption. However, contrary results were shown on vanadium/V3+, manganese/Mn2+, iron/Fe3+, copper/Cu2+, zinc/Zn2+, and aluminum/Al3+ absorption, which showed low MDH activity and cells biomass.

Microbial mineralization of cellulose in frozen soils

High-latitude soils store ~40% of the global soil carbon and experience winters of up to 6 months or more. The winter soil CO2 efflux importantly contributes to the annual CO2 budget. Microorganisms can metabolize short chain carbon compounds in frozen soils. However, soil organic matter (SOM) is dominated by biopolymers, requiring exoenzymatic hydrolysis prior to mineralization. For winter SOM decomposition to have a substantial influence on soil carbon balances it is crucial whether or not biopolymers can be metabolized in frozen soils. We added 13C-labeled cellulose to frozen (−4 °C) mesocosms of boreal forest soil and followed its decomposition. Here we show that cellulose biopolymers are hydrolyzed under frozen conditions sustaining both CO2 production and microbial growth contributing to slow, but persistent, SOM mineralization. Given the long periods with frozen soils at high latitudes these findings are essential for understanding the contribution from winter to the global carbon balance.

Hydrogen isotope and molecular alteration of n-alkanes during heating in open and closed systems

We conducted a series of heating experiments using pure n-alkane mixtures and natural soil organic extracts to evaluate isotopic and molecular changes during cracking and exchange associated with thermal alteration. Experiments included controlled heating of pure n-alkane mixtures (C7–C40) and a total lipid extract from a modern wetland sediment under both ambient air and anhydrous, closed-system conditions. In an argon-purged, closed-system (at temperatures of 60–300°C), the distribution of pure n-alkane mixtures predictably shifted towards a higher proportion of shorter chain lengths (< C20), with no odd-over-even preference. During the heating process, the δ2H values of long-chain n-alkanes (> C20) became 2H-enriched by up to 12‰, while the δ2H of short chain n-alkanes were 2H-depleted by up to 28‰. When repeating these experiments with the total lipid extract from soils, we observed 2H-enrichment of individual n-alkanes and mean-weighted δ2HnC27–31 of soil n-alkanes under both ambient air (up to 15‰ at 300°C over 72h) and Ar-purged, anhydrous, closed-system (up to 10‰ at 300°C over 720h) conditions. Carbon preference indices (CPI) decreased during the thermal alteration process in tandem with isotopic changes. The average chain length (ACL) of the n-alkanes decreased by more than 1 unit during heating, even at temperatures as low as 60°C, when in the ambient air. This highlights the potential for differences in sediment lithology and gas permeability on an outcrop scale to alter primary organic signatures during thermal alteration. In the presence or absence of oxygen, the hydrogen isotopic composition of pure n-alkane mixtures and natural extracts change from the original composition, though for most compounds this was less than 10–15‰ at temperatures below 150°C. The magnitude of change is greatest for shorter chain n-alkanes and at temperatures above 150°C. We conclude that degradation and/or production during heating, such as may be expected during sediment burial or contact heating, could drive shifts in the measured hydrogen isotope composition of sedimentary leaf wax biomarkers. This is especially rapid at temperatures in excess of 200°C, but the magnitude of isotopic change is generally in the range 10–15‰ before the loss of compounds reaches levels that are below analytical relevance for isotope work. Collectively, our results highlight the need for careful consideration of the depositional environment (particularly for information pertaining to oxygen availability) when interpreting molecular and/or isotopic information from sedimentary alkanes. In addition, they also demonstrate the general fidelity of hydrogen isotopes of n-alkanes under shallow burial temperatures with only modest isotopic enrichment prior to complete loss of long carbon chain compounds.

Synthesis and Biological Evaluation of Novel Gigantol Derivatives as Potential Agents in Prevention of Diabetic Cataract.

As a continuation of our efforts directed towards the development of natural anti-diabetic cataract agents, gigantol was isolated from Herba dendrobii and was found to inhibit both aldose reductase (AR) and inducible nitric oxide synthase (iNOS) activity, which play a significant role in the development and progression of diabetic cataracts. To improve its bioefficacy and facilitate use as a therapeutic agent, gigantol (compound 14f) and a series of novel analogs were designed and synthesized. Analogs were formulated to have different substituents on the phenyl ring (compounds 4, 5, 8, 14a-e), substitute the phenyl ring with a larger steric hindrance ring (compounds 10, 17c) or modify the carbon chain (compounds 17a, 17b, 21, 23, 25). All of the analogs were tested for their effect on AR and iNOS activities and on D-galactose-induced apoptosis in cultured human lens epithelial cells. Compounds 5, 10, 14a, 14b, 14d, 14e, 14f, 17b, 17c, 23, and 25 inhibited AR activity, with IC50 values ranging from 5.02 to 288.8 μM. Compounds 5, 10, 14b, and 14f inhibited iNOS activity with IC50 ranging from 432.6 to 1188.7 μM. Compounds 5, 8, 10, 14b, 14f, and 17c protected the cells from D-galactose induced apoptosis with viability ranging from 55.2 to 76.26%. Of gigantol and its analogs, compound 10 showed the greatest bioefficacy and is warranted to be developed as a therapeutic agent for diabetic cataracts.

Fresh and weathered crude oil effects on potential denitrification rates of coastal marsh soil

On April 20, 2010, the Deepwater Horizon oil platform experienced an explosion which triggered the largest marine oil spill in US history, resulting in the release of ∼795 million L of crude oil into the Gulf of Mexico. Once oil reached the surface, changes in overall chemical composition occurred due to volatilization of the smaller carbon chain compounds as the oil was transported onshore by winds and currents. In this study, the toxic effects of both fresh and weathered crude oil on denitrification rates of coastal marsh soil were determined using soil samples collected from an unimpacted coastal marsh site proximal to areas that were oiled in Barataria Bay, LA. The 1:10 ratio of crude oil:field moist soil fully coated the soil surface mimicking a heavy oiling scenario. Potential denitrification rates at the 1:10 ratio, for weathered crude oil, were 46±18.4% of the control immediately after exposure and 62±8.0% of the control following a two week incubation period, suggesting some adaptation of the denitrifying microbial consortium over time. Denitrification rates of soil exposed to fresh crude oil were 51.5±5.3% of the control after immediate exposure and significantly lower at 10.9±1.1% after a 2week exposure period. Results suggest that fresh crude oil has the potential to more severely impact the important marsh soil process of denitrification following longer term exposure. Future studies should focus on longer-term denitrification as well as changes in the microbial consortia in response to oil exposure.