Comparative study on inorganic Cl removal of municipal solid waste fly ash using different types and concentrations of organic acids.

In this study, different organic acids-such as citric, acetic, lactic, propionic, and butyric acid-were evaluated to ascertain the optimum leaching solvent for dechlorinating fly ash. Results suggest that the acid type, concentration, and interactions between both parameters contributed significantly to the variations in the efficiency of fly ash dechlorination. Simple main-effect analysis suggested that a higher acid concentration yields better dechlorination efficiency. However, improvements in dechlorination efficiency did not necessarily yield a low chlorine content leaching residue because in a specific acid concentration region, the increased acid concentration may also accelerate the mass reduction rate of the leaching residue. Experimental results also demonstrate that citric and acetic acid yield the highest dechlorination efficiency, followed by propionic and butyric acid. The least dechlorination efficiency of lactic acid could be attributed to the formation of precipitate (i.e. calcium lactate) which might cover the chlorides and reduce the contact area of intimal chlorides with the leaching solvent. Therefore, a specific concentration of organic matter fermentation broth rich in citric and acetic radicals may present itself as an ideal water substitute for fly ash dechlorination.

Design, synthesis and antiviral evaluation of novel acyclic phosphonate nucleotide analogs with triazolo[4,5-b]pyridine, imidazo[4,5-b]pyridine and imidazo[4,5-b]pyridin-2(3H)-one systems.

A new series of phosphonylated triazolo[4,5-b]pyridine (1-deaza-8-azapurine), imidazo[4,5-b]pyridine (1-deazapurine) and imidazo[4,5-b]pyridin-2(3H)-one (1-deazapurin-8-one) were synthesized from 2-chloro-3-nitropyridine and selected diethyl É·-aminoalkylphosphonates followed by reduction of the nitro group and cyclization. In the final step O,O-diethylphosphonates were transformed into the corresponding phosphonic acids. All synthesized compounds were evaluated in vitro for inhibitory activity against a broad variety of DNA and RNA viruses and their cytotoxic potencies were also established. Compound 12f showed marginal activity against cytomegalovirus Davis strain (EC50 = 76.47 µM) in human embryonic lung (HEL) cells while compounds 10g (EC50 = 52.53 µM) and 12l (EC50 = 61.70 µM) were minimally active against the varicella-zoster virus Oka strain in HEL cells. Compounds under investigation were not cytotoxic at the maximum concentration evaluated (100 µM).

Kinetics and mechanistic study on degradation of prednisone acetate by ozone.

Prednisone acetate (PNSA) is one of the regular glucocorticoid medicines that have been detected in surface water. In this work, the removal of PNSA by ozone was systematically studied under various conditions, and degradation intermediates and reaction pathways were proposed. The results showed that aqueous ozonation was able to remove PNSA effectively, and low pH favored this reaction. The addition of tertiary butanol did not inhibit the oxidation of PNSA by ozone, suggesting that the degradation was caused mainly by the direct oxidation effect of ozone molecules. Moreover, the presence of carboxylated or hydroxylated multiwalled carbon nanotubes can enhance the removal efficiency of PNSA by ozone. Under neutral and acidic conditions, the degradation of PNSA followed pseudo-first-order reaction. Seven intermediates were detected via liquid chromatography-mass spectrometry, and the degradation pathways were then proposed by considering the relative charge density of the frontier orbitals calculated with the Gaussian program. The electrophilic reaction and the Criegee mechanism were the primary reaction mechanisms in the degradation of PNSA by ozone. Formic acid, acetic acid, and oxalic acid were detected as the final reaction products via ion chromatography. Additionally, the aquatic toxicity of the ozonation products was predicted using ECOSAR method. The biodegradation potentials of the pollutant and the ozonation products were estimated using BIOWINTM, suggesting that O3 treatment could significantly enhance the biodegradable potentials of PNSA and its transformation intermediates in the biological post-treatment process. This work can provide useful information for the treatment of PNSA-containing wastewaters.

Gas chromatographic Analysis of Organic Acids in Japanese Green Tea Leaves.

Herein, gas chromatography is used to determine and quantify organic acids in Japanese green tea leaves, and the established method is employed to profile the acid components of Matcha, Gyokuro, Sencha green teas, and green tea varieties and thus acquire data needed to ensure the high quality and safety of green tea. The tea leaves were esterified with 10 vol% sulfuric acid in 1-butanol at 100℃ for 2 h. Oxalic acid contents were high in Asatsuyu and Okuyutaka samples and were low in Sofu, increasing in the order of Sencha < Gyokuro < Matcha, while citric acid content increased in the order of Sencha < Matcha < Gyokuro. Moreover, the oxalic acid content of Gyokuro only slightly increased with increasing tea grade. The relative contents of the different fatty acids did not strongly vary between the different green tea varieties. However, the n-3 to n-6 ratio was found to be low in Sofu. The progressing maturity increased the n-3 to n-6 ratio of Yabukita. The n-3 to n-6 ratio was low in high-grade Matcha, Gyokuro, Sencha green teas, and was related to the green tea quality. The developed method was concluded to be suitable for the evaluation of green tea quality.

Membrane intercalation-enhanced photodynamic inactivation of bacteria by a metallacycle and TAT-decorated virus coat protein.

Antibiotic resistance has become one of the major threats to global health. Photodynamic inactivation (PDI) develops little antibiotic resistance; thus, it becomes a promising strategy in the control of bacterial infection. During a PDI process, light-induced reactive oxygen species (ROS) damage the membrane components, leading to the membrane rupture and bacteria death. Due to the short half-life and reaction radius of ROS, achieving the cell-membrane intercalation of photosensitizers is a key challenge for PDI of bacteria. In this work, a tetraphenylethylene-based discrete organoplatinum(II) metallacycle (1) acts as a photosensitizer with aggregation-induced emission. It self-assembles with a transacting activator of transduction (TAT) peptide-decorated virus coat protein (2) through electrostatic interactions. This assembly (3) exhibits both ROS generation and strong membrane-intercalating ability, resulting in significantly enhanced PDI efficiency against bacteria. By intercalating in the bacterial cell membrane or entering the bacteria, assembly 3 decreases the survival rate of gram-negative Escherichia coli to nearly zero and that of gram-positive Staphylococcus aureus to ∼30% upon light irradiation. This study has wide implications from the generation of multifunctional nanomaterials to the control of bacterial infection, especially for gram-negative bacteria.

Quality characteristics of pork loin cured with green nitrite source and some organic acids.

This study was conducted to improve the quality characteristics of cured meat with natural nitrite. Control and treatment were conducted as follows: nitrite free, marinated with sodium nitrite and ascorbic acid, marinated with only fermented spinach (FS), and marinated with FS adding ascorbic acid, malic acid, citric acid, and tartaric acid. Treatments were pickled with regulated brine (8% salt and 0.08% nitrite). Cured meat with FS adding ascorbic acid, malic acid, and citric acid had higher redness values than sodium nitrite with ascorbic acid on cooked meat. There was a positive effect on lipid oxidation except for citric acid. Protein degradation appeared more in malic acid and tartaric acid treatment than others. Residual nitrite level was lower when adding organic acids. Among various organic acid, ascorbic acid had the highest efficient on quality properties of cured meat. Thus, ascorbic acid was a proper ingredient when curing meat product.

Recent Advances in Applications of Acidophilic Fungi to Produce Chemicals.

Processing of fossil fuels is the major environmental issue today. Biomass utilization for the production of chemicals presents an alternative to simple energy generation by burning. Lignocellulosic biomass (cellulose, hemicellulose and lignin) is abundant and has been used for variety of purposes. Among them, lignin polymer having phenyl-propanoid subunits linked together either through C-C bonds or ether linkages can produce chemicals. It can be depolymerized by fungi using their enzyme machinery (laccases and peroxidases). Both acetic acid and formic acid production by certain fungi contribute significantly to lignin depolymerization. Fungal natural organic acids production is thought to have many key roles in nature depending upon the type of fungi producing them. Biological conversion of lignocellulosic biomass is beneficial over physiochemical processes. Laccases, copper containing proteins oxidize a broad spectrum of inorganic as well as organic compounds but most specifically phenolic compounds by radical catalyzed mechanism. Similarly, lignin peroxidases (LiP), heme containing proteins perform a vital part in oxidizing a wide variety of aromatic compounds with H2O2. Lignin depolymerization yields value-added compounds, the important ones are aromatics and phenols as well as certain polymers like polyurethane and carbon fibers. Thus, this review will provide a concept that biological modifications of lignin using acidophilic fungi can generate certain value added and environmentally friendly chemicals.

Assessing and Reporting Household Chemicals as a Novel Tool to Mitigate Pesticide Residues in Spinach (Spinacia oleracea).

Non-selective use of pesticide to increase productivity leaves residues on crops. These pesticides after consumption have a detrimental effect on human health and their intake can lead to various diseases such as kidney damage, neurological disorders, cardiovascular diseases, circulatory and reproductive problems. The recent study was designed to assess the effects of household processing treatments such as acidic solutions (acidic acid and citric acid), alkaline solutions (sodium chloride and sodium carbonate) and biological solutions (radish, ginger, garlic, and lemon extracts) were evaluated for their efficiency for removal of pesticides in spinach by gas chromatography with electron capture detector (GC-ECD). The results showed that pesticide residues were sharply reduced when spinach was exposed to washing treatments. The results showed that the greatest reduction of deltamethrin, cypermethrin, chlorpyrifos and endosulfan with 10% acetic acid was (79.68 ± 0.81%), (89.99 ± 0.12%), (94.21 ± 0.02%) and (70.32 ± 0.25%), respectively of tested washing solutions. The acidic solutions were more effective than alkaline and biological extracts in the removal of pesticide residues. The average reduction in various washing solutions ranged from 10.21 to 79.68%, 22.60 to 89.48%, 22.95 to 94-21% and 11.24-70.32% for the removal of deltamethrin, cypermethrin, chlorpyrifos, and endosulfan, respectively.

Investigation of isomeric structures in a commercial mixture of naphthenic acids using ultrahigh pressure liquid chromatography coupled to hybrid traveling wave ion mobility-time of flight mass spectrometry.

The separation of isomeric naphthenic acids (NAs) is of high importance to obtain more detailed and therefore useful information to understand their fate, transport, toxicity and potential removal treatment methodologies. In the current study, the capabilities of the ultrahigh pressure liquid chromatography/traveling wave ion mobility-time of flight mass spectrometry (UPLC/TWIM-TOF-MS) to separate and study different isomeric structures of NAs were investigated. Fifty seven standard compounds belonging to different chemical families of classical NAs were analyzed to obtain their experimental drift times in addition to chromatographic retention time and mass-to-charge information (m/z). These acyclic and cyclic molecules yielded ions with collision cross section (CCS) values ranging from 110 to 210 Å2. The feasibility of the UPLC/TWIM-TOF-MS method to provide a higher degree of confidence in the identification of isomeric structures was evaluated by analyzing the commercial (Sigma-Aldrich) NAs mixture. Identification and structure confirmation of several alicyclic compounds of similar m/z in the NAs mixture were possible by this method. For instance, the presence of previously tentatively identified compounds by the ultrahigh pressure liquid chromatography/quadrupole time of flight mass spectrometry (UPLC/QTOF-MS), such as 4-tert-butylcyclohexanoic acid, 4-dicyclohexylacetic acid or 3,5-dimethyladamantane-1-carboxylic acid, was confirmed. Combining ion mobility separation with UPLC/TOF-MS gives a higher level of selectivity to the overall method by selective interrogation of specific retention time, mass-to-charge and mobility regions. However, there are cases where it is not possible to resolve many similar molecules such as acyclic isomeric compounds in commercial NAs mixture by this technique. This was likely due to the very small CCS area differences among the structural isomeric species. Considerable improvements in the ion mobility resolution and separation will be required for this technique to be able to resolve isomeric species with slight differences in physicochemical properties (e.g., size and structure).

Synthesis of Cyclic and Acyclic Pyrimidine Nucleosides Analogues with Anticipated Antiviral Activity.

A convenient method for preparation of cyclic and acyclic nucleosides was achieved by alkylation of 6-(2,4-dichlorophenoxymethyl) pyrimidine-2,4-dione (1) with a variety of acyclic and cyclic activated sugar analogues, namely (2-acetoxyethoxy)methyl acetate (3), 2-(acetoxymethoxy)propane-1,3-diyl dibenzoate (4), benzyloxymethyl acetate (5), 2-acetoxy-5-(benzoyloxymethyl)tetrahydrofuran-3,4-diyl dibenzoate (12), 5-chloro-2-((4-chlorobenzoyloxy)methyl) tetrahydrofuran-3-yl 4-chlorobenzoate (13) and 2-(acetoxymethyl)-6-bromotetrahydro-2H-pyran-3,4,5-triyl triacetate (14), respectively. Deprotection of the synthesized nucleosides was achieved by using methanolic ammonia. The structures of the newly synthesized nucleoside analogues were fully characterized by analytical methods (mass spectrometry, 1H NMR, 13C NMR, and elemental analysis).

Flavor Compounds in Pixian Broad-Bean Paste: Non-Volatile Organic Acids and Amino Acids.

Non-volatile organic acids and amino acids are important flavor compounds in Pixian broad-bean paste, which is a traditional Chinese seasoning product. In this study, non-volatile organic acids, formed in the broad-bean paste due to the metabolism of large molecular compounds, are qualitatively and quantitatively determined by high-performance liquid chromatography (HPLC). Amino acids, mainly produced by hydrolysis of soybean proteins, were determined by the amino acid automatic analyzer. Results indicated that seven common organic acids and eighteen common amino acids were found in six Pixian broad-bean paste samples. The content of citric acid was found to be the highest in each sample, between 4.1 mg/g to 6.3 mg/g, and malic acid were between 2.1 mg/g to 3.6 mg/g ranked as the second. Moreover, fumaric acid was first detected in fermented bean pastes albeit with a low content. For amino acids, savory with lower sour taste including glutamine (Gln), glutamic acid (Glu), aspartic acid (Asp) and asparagines (Asn) were the most abundant, noted to be 6.5 mg/g, 4.0 mg/g, 6.4 mg/g, 4.9 mg/g, 6.2 mg/g and 10.2 mg/g, and bitter taste amino acids followed. More importantly, as important flavor materials in Pixian broad-bean paste, these two groups of substances are expected to be used to evaluate and represent the flavor quality of Pixian broad-bean paste. Moreover, the results revealed that citric acid, glutamic acid, methionine and proline were the most important flavor compounds. These findings are agreat contribution for evaluating the quality and further assessment of Pixian broad-bean paste.

Copper(II)nitrate catalyzed regioselective protection of primary alcohols with 4,4'-dimethoxytrityl and 2,7-dimethyl-9-phenyl xanthen-9-yl groups in nucleosides and carbohydrates.

Regioselective protection of primary hydroxyl group in nucleoside and carbohydrate analogs was accomplished using dimethoxytrityl alcohol (DMTr-OH) or dimethylpixyl alcohol (DMPx-OH) in presence of copper(II)nitrate as a Lewis acid catalyst. Excellent selectivity was observed for the protection of primary hydroxyl group over secondary while glycosidic bond remain unaffected. Utility of this methodology was further exemplified via DMTr- and DMPx-protection of alipahtic acyclic and cyclic diols.

Synthesis and cytotoxic activity of novel acyclic nucleoside analogues with functionality in click chemistry.

We describe synthesis of novel acyclic nucleoside analogues which are building blocks for CuAAC reaction and their activity against two types of human cancer cell lines (HeLa, KB). Three of chosen compounds show promising cytotoxic activity. Synthesis pathway starting from simple and easily accessible substrates employing DMT or TBDPS protective groups is described. Adenosine and thymidine analogues containing alkyne moiety and adenosine analogue containing azido group were synthesized. The obtained units showed ability of forming triazole motif under the CuAAC reaction conditions.

Organic acid pretreatment of oil palm trunk: effect on enzymatic saccharification and ethanol production.

Effective lignocellulosic biomass saccharification is one of the crucial requirements of biofuel production via fermentation process. Organic acid pretreatments have been gained much interests as one of the high potential methods for promoting enzymatic saccharification of lignocellulosic materials due to their lower hazardous properties and lower production of inhibitory by-products of fermentation than typical chemical pretreatment methods. In this study, three organic acids, including acetic acid, oxalic acid, and citric acid, were examined for improvement of enzymatic saccharification and bioethanol production from oil palm trunk biomass. Based on response surface methodology, oxalic acid pretreated biomass released the maximum reducing sugar of 144 mg/g-pretreated biomass at the optimum condition, which was higher than untreated samples for 2.30 times. The released sugar yield of oil palm trunk also corresponded to the results of FT-IR analysis, which revealed the physical modification of cellulose and hemicellulose surface structures of pretreated biomass. Nevertheless, citric acid pretreatment is the most efficient pretreatment method to improve bioethanol fermentation of Saccharomyces cerevisiae TISTR 5606 at 1.94 times higher than untreated biomass. These results highlighted the selection of organic acid pretreatment as a potential method for biofuel production from oil palm trunk feedstocks.

Liposomal Circular Dichroism (L-CD) of Arenoyl Derivatives of Sphingolipids. Amplification of Cotton Effects in Ordered Lipid Bilayers.

Liposomal circular dichroism (L-CD) of acyclic amino alcohols exhibit amplification of Cotton effects when measured in highly uniform, unilamellar liposomes. The effect is likely due to intermolecular associations-H-aggregates-that self-assemble spontaneously within the lipid bilayer, and persists over long time scales. L-CD spectra of N,O,O'-tri-(6'methoxy-2'-naphthoyl)-d-erythro-sphingosine, or the corresponding dihydro-derivative (sphinganine), shows ~10-fold amplification of magnitudes of Cotton effects over conventional CD spectra recorded in isotropic solution.

The effect of low-molecular-weight organic acids on copper toxicity in E. fetida in an acute exposure system.

In the present study, the effects of low-molecular-weight organic acids (OAs) on the toxicity of copper (Cu) to the earthworm Eisenia fetida (E. fetida) were investigated in a simulated soil solution. We exposed E. fetida to soil solution containing Cu and a variety of OAs (acetic acid, oxalic acid, citric acid, and EDTA). We found that the addition of OAs reduced the toxicity of Cu to E. fetida, where the reduction was strongest in EDTA and weakest in acetic acid. These compounds decreased the mortality rate of E. fetida that were exposed to Cu and reduced levels of antioxidant enzymes and malondialdehyde to unexposed control levels. E. fetida were exposed to Cu with OAs had reduced Cu2+, which were likely caused by Cu forming complexes with the OAs, reducing the availability of Cu. The presence of OAs also reduced Cu-induced damage on earthworm cellular ultrastructures and changed the subcellular distribution of Cu. These results demonstrated that OAs could reduce the toxicity, as well as the bioavailability, of heavy metals in soil solutions where both OAs and heavy metals often coexist.

Combined effects of low-molecular-weight organic acids on mobilization of arsenic and lead from multi-contaminated soils.

A batch experiment was conducted to examine the combined effects of three common low-molecular-weight organic acids (LMWOAs) on the mobilization of arsenic and lead in different types of multi-contaminated soils. The capacity of individual LMWOAs (at a same molar concentration) to mobilize soil-borne As and Pb varied significantly. The combination of the organic acids did not make a marked "additive" effect on the mobilization of the investigated three elements. An "antagonistic" effect on element mobilization was clear in the treatments involving oxalic acid for some soils. The acid strength of a LMWOA did not play an important role in controlling the mobilization of elements. While the mobilization of As and Pb was closely associated with the dissolution of soil-borne Fe, soil properties such as original soil pH, organic matter contents and the total amount of the element relative to the total Fe markedly complicated the mobility of that element. Aging led to continual consumption of proton introduced from addition of LMWOAs and consequently caused dramatic changes in solution-borne Fe, which in turn resulted in change in As and Pb in the soil solution though different elements behaved differently.

Synthesis and characterization of new low-cost ILs based on butylammonium cation and application to lignocellulose hydrolysis.

Fourteen ionic liquids (ILs) were obtained and characterized by nuclear magnetic resonance and infra-red spectroscopy. One of these liquids, n-butylammonium acetate, was used in the treatment of coir fiber prior to acid hydrolysis. For this purpose, the fiber was pulped with 8% (w/w) sodium hydroxide for 6h under 2.5 atm pressure at 137°C and then treated with IL for 2h at 90°C. The samples were hydrolyzed in acetic acid at different concentrations and temperatures. The reducing sugar concentrations were determined in all samples, and the optimal hydrolysis conditions were established (32.2% acetic acid at 122.4°C). The reaction time was also studied, and the conversion was maximized at 3h. Under the best hydrolysis conditions, crude fiber, pulping fiber, and IL-treated fiber were hydrolyzed to yield 8.53%, 47.58%, and 89.75% of reducing sugars, respectively.

Different low-molecular-mass organic acids specifically control leaching of arsenic and lead from contaminated soil.

Low-molecular-mass organic acids (LMMOA) are of key importance for mobilisation and fate of metals in soil, by functioning as ligands that increase the amount of dissolved metal in solution or by dissociation of metal binding minerals. Column leaching experiments were performed on soil polluted with As and Pb, in order to determine the specificity of LMMOA related release for individual elements, at varying organic acid concentrations. Acetic, citric and oxalic acids were applied in 12h leaching experiments over a concentration range (0.5-25 mM) to soil samples that represent organic and mineral horizons. The leaching of As followed the order: oxalic>citric>acetic acid in both soils. Arsenic leaching was attributed primarily to ligand-enhanced dissolution of mineral oxides followed by As released into solution, as shown by significant correlation between oxalic and citric acids and content of Al and Fe in leaching solutions. Results suggest that subsurface mineral soil layers are more vulnerable to As toxicity. Leaching of Pb from both soils followed the order: citric>oxalic>acetic acid. Mineral soil samples were shown to be more susceptible to leaching of Pb than samples characterised by a high content of organic matter. The leaching efficiency of citric acid was attributed to formation of stable complexes with Pb ions, which other acids are not capable of. Results obtained in the study are evidence that the extent of As and Pb leaching in contaminated surface and subsurface soil depends significantly on the types of carboxylic acid involved. The implications of the type of acid and the specific element that can be mobilised become increasingly significant where LMMOA concentrations are highest, such as in rhizosphere soil.

Landscape of π-π and sugar-π contacts in DNA-protein interactions.

There were 1765 contacts identified between DNA nucleobases or deoxyribose and cyclic (W, H, F, Y) or acyclic (R, E, D) amino acids in 672 X-ray structures of DNA-protein complexes. In this first study to compare π-interactions between the cyclic and acyclic amino acids, visual inspection was used to categorize amino acid interactions as nucleobase π-π (according to biological edge) or deoxyribose sugar-π (according to sugar edge). Overall, 54% of contacts are nucleobase π-π interactions, which involve all amino acids, but are more common for Y, F, and R, and involve all DNA nucleobases with similar frequencies. Among binding arrangements, cyclic amino acids prefer more planar (stacked) π-systems than the acyclic counterparts. Although sugar-π interactions were only previously identified with the cyclic amino acids and were found to be less common (38%) than nucleobase-cyclic amino acid contacts, sugar-π interactions are more common than nucleobase π-π contacts for the acyclic series (61% of contacts). Similar to DNA-protein π-π interactions, sugar-π contacts most frequently involve Y and R, although all amino acids adopt many binding orientations relative to deoxyribose. These DNA-protein π-interactions stabilize biological systems, by up to approximately -40 kJ mol(-1) for neutral nucleobase or sugar-amino acid interactions, but up to approximately -95 kJ mol(-1) for positively or negatively charged contacts. The high frequency and strength, despite variation in structure and composition, of these π-interactions point to an important function in biological systems.