Prior Chemical Treatment Research Articles

Estudio palinológico de las Licofitas (Lycopodiopsida) de las Sierras Pampeanas centrales de Argentina

Background and aims: The Sierras Pampeanas Centrales of Argentina constitute the fourth centre of diversity of lycophytes and ferns in the Cono Sur, where representatives of four families of lycophytes live: Huperziaceae, Lycopodiaceae, Isoetaceae and Selaginellaceae. The aim of this work is to provide data of the morphology of their spores observed with optical and scanning electron microscopes, as a contribution to the taxonomy and conservation. M&M: The materials were analysed without prior chemical treatment and photographic records were obtained with both observation equipments. Results: The morphological diagnostic features of the spores are presented. The Huperziaceae and Lycopodiaceae are isosporous with trilete spores. Huperziaceae presents foveolated or fossulated spores, while Lycopodiaceae spores are reticulate, scabrate and baculate. In Isoetes hieronymi (heterosporate), the microspores are monolete with echinate ornamentation, while the megaspores are trilete, with reticulate ornamentation. The Selaginellaceae, all heterosporate, produce trilete microspores and megaspores, both with varied ornamentation. Conclusions: Spore characteristics provide relevant information for regional floristic studies as well as for taxonomic assignments, both of extant flora and fossil records. Also, for studies of the composition of soil spore banks as a tool for the conservation of local floristic biodiversity.

Elemental concentrations of seven types of green vegetables grown on small-scale farmlands in rural areas of Japan: Differences according to the type and place of production

We collected seven types of green vegetables produced in 11 areas of Japan and analyzed their elemental concentrations. Halogen analyses were performed with and without prior chemical treatment. The most popular type of spinach exhibited the highest concentrations of Mg, K, and Zn, and the lowest concentrations of alkaline earths (Ca and Sr) and halogens (Cl and Br). Japanese mustard spinach, the second most consumed type of spinach in Japan, exhibited the highest concentrations of P, S, Ca, Fe, and Br and adequate amounts of other essential elements. The other five green vegetables had unique elemental concentrations. In particular, radish had the highest concentrations of Ca, Na, and Cl and the lowest concentrations of Mg, P, Cu, and Zn. Leaves and stalks were separately analyzed. Fe, Cu, Zn, and Mn concentrations tended to be higher in leaves, and K, Na, and Rb concentrations were higher in stalks. Halogen (Cl and Br) concentrations in Japanese mustard spinach produced on farmland near the coast were remarkably high, suggesting an effect of sea salt. However, even in green vegetables produced near the coast, halogen uptake clearly differed by production area. The concentrations of Cl and Br in Japanese mustard spinach produced in two coastal areas were very high and were not removed by washing, but were mostly lost after boiling samples from Taneichi for 3[Formula: see text]min. In contrast, there was no difference in Na concentrations among vegetables produced in coastal and inland areas. The concentrations of essential elements such as Mg, Ca, and Fe were clearly higher in green vegetables from small- versus large-scale production areas, perhaps attributable to differences in the farming methods employed.

Comparative study of lignin and sodium lignosulfonate extracted from irradiated and non-irradiated sawdust wastes

Recent technologies in the production of chemicals and bio-material products are focusing on lignocellulosic biomass resources since it is the world's most abundant economical material, recyclable, sustainable, low cost, as well as highly renewable natural resources. This biomass refers to agricultural wastes such as woody plants (soft and hardwood). Lignin is extracted from these agro-wastes using chemical methods and ionizing radiation. The outcome of employing gamma radiation as a pretreatment step prior chemical treatment on the duration for alkaline, acid, and production of sodium lignosulfonate (NaLS) was examined. The structure of the produced NaLS was verified utilizing Nuclear magnetic resonance (1H-NMR, 13C-NMR) and Liquid chromatography–mass spectrometry (LC–MS). A comparison between the physicochemical properties of sodium lignosulfonate extracted from both non-irradiated and irradiated sawdust waste was studied using FTIR, XRD, EDX and TGA. The degree of sulfonation of the produced NaLS was determined utilizing the potentiometric titration method. The findings demonstrated that gamma exposure pretreatment step reduces the time of alkaline, acid, and sulfonation processes as well as a higher yield percentage and degree of sulfonation.

A dual-purpose polymerase engineered for direct sequencing of pseudouridine and queuosine.

More than 170 posttranscriptional RNA modifications are so far known on both coding and noncoding RNA species. Within this group, pseudouridine (Ψ) and queuosine (Q) represent conserved RNA modifications with fundamental functional roles in regulating translation. Current detection methods of these modifications, which both are reverse transcription (RT)-silent, are mostly based on the chemical treatment of RNA prior to analysis. To overcome the drawbacks associated with indirect detection strategies, we have engineered an RT-active DNA polymerase variant called RT-KTq I614Y that produces error RT signatures specific for Ψ or Q without prior chemical treatment of the RNA samples. Combining this polymerase with next-generation sequencing techniques allows the direct identification of Ψ and Q sites of untreated RNA samples using a single enzymatic tool.

Effect of Agave americana fibers used as reinforcement in the preparation of composites based on recycled PVC

AbstractThis work deals with the preparation and the study of a new composite obtained from a thermoplastic polymer and a vegetal fiber. The polymer used is a recycled polyvinylchloride (PVC) and the fiber used was extracted from Agave americana, a plant which grows easily under Mediterranean type climates. Prior chemical treatment of the extracted fiber was necessary to modify the surface of the fiber in order to optimize the adhesion between this fiber and the recycled PVC during the preparation of composites from these materials. For this purpose, our investigations led us to attempt various reactions modification of the surface fiber. The method that gave the best results consists of an alkaline treatment followed by a reaction with acetic anhydride. Once completed chemicals treatments of fiber, the material is mixed with the recycled PVC which serves as a matrix to prepare composites at varying rates from 5% to 30% by weight of agave modified fibers. The effects of the incorporation of raw and processed agave fibers on the mechanical, thermal and morphological properties of PVC/agave fiber composites were examined and discussed.

Anchoring single platinum atoms onto nickel nanoparticles affords highly selective catalysts for lignin conversion

Due to the highly complex polyphenolic structure of lignin, depolymerization without a prior chemical treatment is challenging, and new catalysts are required. Atomically dispersed catalysts are able to maximize the atomic efficiency of noble metals, simultaneously providing an alternative strategy to tune the activity and selectivity by alloying with other abundant metal supports. Here, we report a highly active and selective catalyst comprising monodispersed (single) Pt atoms on Ni nanoparticles supported on carbon (denoted as Pt 1 Ni/C, where Pt 1 represents single Pt atoms), designed for the reductive depolymerization of lignin. Selectivity toward 4-n-propylsyringol and 4-n-propylguaiacol exceeds 90%. The activity and selectivity of the Pt 1 Ni/C catalyst in the reductive depolymerization of lignin may be attributed to synergistic effects between the Ni nanoparticles and the single Pt atoms. • An efficient single-atom alloy catalyst for lignin-first biorefining is disclosed • The catalyst shows high activity in lignin deconstruction to afford aromatic monomers • Key structural and mechanistic features of the catalyst are provided Alloying noble metal atoms with non-noble metals allows the atomic efficiency of the noble metal to be maximized. Chen et al. describe single-atom catalysts for reductive lignin depolymerization based on platinum single atoms anchored onto nickel nanoparticles and supported on carbon, which are highly efficient, with the structure of the catalysts determining the selectivity of the reaction.

Non-covalent double bond sensors for gas-phase infrared spectroscopy of unsaturated fatty acids

The position and configuration of carbon-carbon double bonds in unsaturated fatty acids is crucial for their biological functions and influences health and disease. However, double bond isomers are not routinely distinguished by classical mass spectrometry workflows. Instead, they require sophisticated analytical approaches usually based on chemical derivatization and/or instrument modification. In this work, a novel strategy to investigate fatty acid double bond isomers (18:1) without prior chemical treatment or modification of the ion source was implemented by non-covalent adduct formation in the gas phase. Fatty acid adducts with sodium, pyridinium, trimethylammonium, dimethylammonium, and ammonium cations were characterized by a combination of cryogenic gas-phase infrared spectroscopy, ion mobility-mass spectrometry, and computational modeling. The results reveal subtle differences between double bond isomers and confirm three-dimensional geometries constrained by non-covalent ion-molecule interactions. Overall, this study on fatty acid adducts in the gas phase explores new avenues for the distinction of lipid double bond isomers and paves the way for further investigations of coordinating cations to increase resolution.Graphical abstract

Embedding Single Platinum Atoms Into Nickel Nanoparticles Affords Highly Selective Catalysts for Lignin Conversion

Lignin is an abundant biomass source that can be converted into value-added aromatic platform chemicals. Due to the highly complex polyphenolic-structure of lignin, depolymerisation without a prior chemical treatment is challenging, and new, superior catalysts are required. Atomically dispersed catalysts containing isolated atoms are able to maximize the atomic efficiency of noble metals in a catalytic process, simultaneously providing an alternative strategy to tune the activity and selectivity by alloying with other abundant metal supports. Herein, we report a highly active and selective catalyst comprising monodispersed (single) Pt atoms on Ni nanoparticles supported on carbon (denoted as Pt1Ni/C where Pt1 represent single Pt atoms), designed for the reductive depolymerization of lignin. Selectivity towards 4-n-propylsyringol and 4-n-propylguaiacol, in which the aromatic rings are preserved, exceeds 90%. The activity and selectivity of the engineered Pt1Ni/C catalyst in the reductive depolymerization of lignin may be attributed to synergistic effects between the Ni nanoparticles that promote dissociation of H2 and supply the absorbed hydrogen to the single Pt atoms where cleavage of the C-O bonds takes place.

Develepment of Catalystic Systems for Electroreduction of Highly Inert Reactants Such As Arsenate, Nitrite and Oxohalogenates

Noble metal nanoparticles (Pt, Rh, Ir Pd), when deposited on an inert electrode substrates, exhibit electrocatalytic properties during both oxidation of As(III) and reduction of As(V) in acid medium (e.g. 0.5 mol dm-3 H2SO4). For example, upon application of the appropriate potential, both As(III) and As(V) are preconcentrated on surfaces of Pt nanoparticles. Consequently, their presence can monitored under voltammetric conditions. Population of protons does affect the systems’ electrochemical characteristics. The nature of arsenic voltammetric peaks is strongly dependent on the preconcentration potential. While the reduction and deposition of As(III) is induced by adsorbed hydrogen on Pt formed at potentials lower than 0.25 V (vs. RHE), the adsorption and preconcentration of As(V) can be readily achieved at Pt oxides generated at Pt nanoparticles at potentials higher than 0.85 V (vs. RHE). From mechanistic point of view, voltammetric oxidation of bulk As(III) is catalyzed by Pt oxo species but electrocatalytic reduction of As(V) requires its prior adsorption. Electroreduction of the resulting As(V) adsorbates is catalyzed by both metallic platinum and by platinum on which hydrogen atoms are adsorbed; the resulting voltammetric peak current densities are dependent on concentration of As(V) in solution. A unique feature of the adsorbed As(III) and As(V) oxo species is the ability to agglomerate and form stable polynuclear electroactive films on Pt nanoparticles. Their performance resembles behavior of redox conducting polymers, and their redox transitions are fast and reversible. Electrochemical experiments are supported by the data from scanning and transmission electron microscopies and Raman spectroscopy.In conclusion, the present observations demonstrate the utility of Pt nanoparticles as the catalytic system for inducing of (otherwise highly inert) electrode processes of As(III) and As(V) in acid medium. While the electrocatalytic activity of platinum (particularly PtO) toward electrooxidation of As(III) was previously postulated, we clearly show here that arsenates(V) can be adsorbed, preconcentrated, and electrocatalytically reduced (without prior chemical treatment) and, thus, detected on surfaces of Pt nanostructures. On mechanistic grounds, As(V) must be first adsorbed on bare (metallic) Pt surface before the actual electron transfer can take place. In addition to the structural importance, ivolvement of protons is crucial to effective electrocatalysis. It is also noteworthy that the current signals can be correlated to concentration of As(V) in bulk solution. The present study also provides evidence of obtaining a stable redox-polymer-like As(III,V) oxo film capable of fast charge propagation (electron-self exchange rate on the level 8*106 dm3 mol-1 s-1) within the adsorbed layer existing on surfaces of platinum nanoparticles. The latter observation is of both fundamental and analytical significance. Observations made during electrocatalytic and photoelectrochemical reductions of bromates, nitrites and carbon dioxide with use of various metal nanoparticles and nanostructured metal oxides can serve as guides for such research.

Physicochemical Evaluation of the Oil Extracted from Anacardium occidentale Almonds for Energy Use

The present study aimed at exploring the potential of producing biofuels from unconventional vegetable oils extracted from Anacardium occidentale kernels. Accordingly, oils were extracted from Anacardium occidentale kernels and subjected to physical and chemical characterization namely: density; lower calorific value (PCI); quality indexes; fatty acid profile, viscosity using French and ISO standards.
 Results revealed that Anacardium occidentale almonds have a lipidic potential of 52.54%, the transesterification reaction yield was 78.28%. As for the quality indices of the vegetable oil: acidity (˃1%); saponification index (205.29 mg KOH/g-oil); peroxide value (8.08 meq O2/kg-oil) and iodine value (108.84 mg iodine/g-oil) were considerably reduced for biodiesel. The vegetable oil was unsaturated type with the predominance of oleic acid (43.86%). The fuel characteristics of the oil obtained were: acidity (2.89%), density at 40°C (0.796 g/cm3) cetane number (41.47). The raw extracted oil is not usable as fuel for engine due to its very high viscosity ranging 30.69 mm2/s. As a consequence, a prior chemical treatment is necessary to reduce the viscosity. 
 Our results provided an insight on the energetic potential of the investigated oil, with respect to its use as a source for biodiesel in replacement of the current conventional diesel fuel.

(Invited) Develepment of Electrocatalystic Systems for Highly Inert Reactants: Reduction of Arsenic(V), Nitrite, Oxohalogenates and CO2 in Acid Medium

Noble metal nanoparticles (Pt, Rh, Ir Pd), when deposited on an inert electrode substrates, exhibit electrocatalytic properties during both oxidation of As(III) and reduction of As(V) in acid medium (e.g. 0.5 mol dm-3 H2SO4). For example, upon application of the appropriate potential, both As(III) and As(V) are preconcentrated on surfaces of Pt nanoparticles. Consequently, their presence can monitored under voltammetric conditions. Population of protons does affect the systems’ electrochemical characteristics. The nature of arsenic voltammetric peaks is strongly dependent on the preconcentration potential. While the reduction and deposition of As(III) is induced by adsorbed hydrogen on Pt formed at potentials lower than 0.25 V (vs. RHE), the adsorption and preconcentration of As(V) can be readily achieved at Pt oxides generated at Pt nanoparticles at potentials higher than 0.85 V (vs. RHE). From mechanistic point of view, voltammetric oxidation of bulk As(III) is catalyzed by Pt oxo species but electrocatalytic reduction of As(V) requires its prior adsorption. Electroreduction of the resulting As(V) adsorbates is catalyzed by both metallic platinum and by platinum on which hydrogen atoms are adsorbed; the resulting voltammetric peak current densities are dependent on concentration of As(V) in solution. A unique feature of the adsorbed As(III) and As(V) oxo species is the ability to agglomerate and form stable polynuclear electroactive films on Pt nanoparticles. Their performance resembles behavior of redox conducting polymers, and their redox transitions are fast and reversible. Electrochemical experiments are supported by the data from scanning and transmission electron microscopies and Raman spectroscopy.In conclusion, the present observations demonstrate the utility of Pt nanoparticles as the catalytic system for inducing of (otherwise highly inert) electrode processes of As(III) and As(V) in acid medium. While the electrocatalytic activity of platinum (particularly PtO) toward electrooxidation of As(III) was previously postulated, we clearly show here that arsenates(V) can be adsorbed, preconcentrated, and electrocatalytically reduced (without prior chemical treatment) and, thus, detected on surfaces of Pt nanostructures. On mechanistic grounds, As(V) must be first adsorbed on bare (metallic) Pt surface before the actual electron transfer can take place. In addition to the structural importance, ivolvement of protons is crucial to effective electrocatalysis. It is also noteworthy that the current signals can be correlated to concentration of As(V) in bulk solution. The present study also provides evidence of obtaining a stable redox-polymer-like As(III,V) oxo film capable of fast charge propagation (electron-self exchange rate on the level 8*106 dm3 mol-1 s-1) within the adsorbed layer existing on surfaces of platinum nanoparticles. The latter observation is of both fundamental and analytical significance. Observations made during electrocatalytic and photoelectrochemical reductions of bromates, nitrites and carbon dioxide with use of various metal nanoparticles and nanostructured metal oxides can serve as guides for such research.

Importance of Interfacial Activation and Proton Transfers during Redox Processes of Highly Inert Systems: Electrocatalytic Detection of As(III) and As(V) in Acid Medium

Noble metal nanoparticles (Pt, Rh, Ir Pd), when deposited on an inert electrode substrates, exhibit electrocatalytic properties during both oxidation of As(III) and reduction of As(V) in acid medium (e.g. 0.5 mol dm-3 H2SO4). For example, upon application of the appropriate potential, both As(III) and As(V) are preconcentrated on surfaces of Pt nanoparticles. Consequently, their presence can monitored under voltammetric conditions. Population of protons does affect the systems’ electrochemical characteristics. The nature of arsenic voltammetric peaks is strongly dependent on the preconcentration potential. While the reduction and deposition of As(III) is induced by adsorbed hydrogen on Pt formed at potentials lower than 0.25 V (vs. RHE), the adsorption and preconcentration of As(V) can be readily achieved at Pt oxides generated at Pt nanoparticles at potentials higher than 0.85 V (vs. RHE). From mechanistic point of view, voltammetric oxidation of bulk As(III) is catalyzed by Pt oxo species but electrocatalytic reduction of As(V) requires its prior adsorption. Electroreduction of the resulting As(V) adsorbates is catalyzed by both metallic platinum and by platinum on which hydrogen atoms are adsorbed; the resulting voltammetric peak current densities are dependent on concentration of As(V) in solution. A unique feature of the adsorbed As(III) and As(V) oxo species is the ability to agglomerate and form stable polynuclear electroactive films on Pt nanoparticles. Their performance resembles behavior of redox conducting polymers, and their redox transitions are fast and reversible. Electrochemical experiments are supported by the data from scanning and transmission electron microscopies and Raman spectroscopy. In conclusion, the present observations demonstrate the utility of Pt nanoparticles as the catalytic system for inducing of (otherwise highly inert) electrode processes of As(III) and As(V) in acid medium. While the electrocatalytic activity of platinum (particularly PtO) toward electrooxidation of As(III) was previously postulated, we clearly show here that arsenates(V) can be adsorbed, preconcentrated, and electrocatalytically reduced (without prior chemical treatment) and, thus, detected on surfaces of Pt nanostructures. On mechanistic grounds, As(V) must be first adsorbed on bare (metallic) Pt surface before the actual electron transfer can take place. In addition to the structural importance, involvement of protons is crucial to effective electrocatalysis. It is also noteworthy that the current signals can be correlated to concentration of As(V) in bulk solution. The present study also provides evidence of obtaining a stable redox-polymer-like As(III,V) oxo film capable of fast charge propagation (electron-self exchange rate on the level 8*106 dm3 mol-1 s-1) within the adsorbed layer existing on surfaces of platinum nanoparticles. The latter observation is of both fundamental and analytical significance. Although the experimental approaches are not optimized here, the detection of As(V) and As(III) down 5*10-6 and 2*10-6 mol dm-3, respectively, is feasible. The main drawback is that the baseline uncertainty limits its routine use in static solutions to concentrations above 2-5*10-6 mol dm-3. This level is not sufficient for practical purposes. For example, the US Environmental Protection Agency (EPA) defines the permissible level of arsenic in drinking water in the United States as 10 μg dm-3 (ca. 1.3*10-7 mol dm-3). Further research is being continued along this line.

Thermolytic Reagents to Synthesize 5′‐ or 3′‐Mono(thio)phosphate Oligodeoxynucleotides or 3′‐modified oligodeoxynucleotides

Methylthioethanol and 2,2′‐thiodiethanol were derivatized into cyanoethyl‐phosphoramidites and solid support and were used to synthesize 5′‐, 3′‐monophosphate or 5′‐, 3′‐monothiophosphate oligonucleotides by thermolytic treatment followed by ammonia. The corresponding 2,2′‐thiodiethanol solid support was also used to release fully protected oligonucleotides from solid support without ammonia treatment, to monitor the oligonucleotide elongation on solid support by MALDI‐TOF mass spectrometry without any prior chemical treatment or to synthesize 3′‐pentynyl oligonucleotides in combination with a modified phosphoramidite where the cyanoethyl group was replaced by a pentynyl one.

Use of large pieces of printed circuit boards for bioleaching to avoid ‘precipitate contamination problem’ and to simplify overall metal recovery

Very recently bioleaching has been used for removing metals from electronic waste. Most of the research has been targeted to using pulverized PCBs for bioleaching where precipitate formed during bioleaching contaminates the pulverized PCB sample and making the overall metal recovery process more complicated. In addition to that, such mixing of pulverized sample with precipitate also creates problems for the final separation of non metallic fraction of PCB sample. In the present investigation we attempted the use of large pieces of printed circuit boards instead of pulverized sample for removal of metals. Use of large pieces of PCBs for bioleaching was restricted due to the chemical coating present on PCBs, the problem has been solved by chemical treatment of PCBs prior to bioleaching. In short,•Large pieces of PCB can be used for bioleaching instead of pulverized PCB sample.•Metallic portion on PCBs can be made accessible to bacteria with prior chemical treatment of PCBs.•Complete metal removal obtained on PCB pieces of size 4cm×2.5cm with the exception of solder traces. The final metal free PCBs (non metallic) can be easily recycled and in this way the overall recycling process (metallic and non metallic part) of PCBs becomes simple.

A New Method for the Analysis of Soluble and Insoluble Oxalate in Pulp and Paper Matrices

A novel method has been developed for determining soluble and insoluble forms of oxalate in pulp and paper samples by ion chromatography. Methanesulphonic acid is used to dissolve insoluble oxalate, and total oxalate is then determined by ion chromatography with suppressed conductivity detection. Soluble oxalate is determined directly by ion chromatography, without prior chemical treatment. Insoluble oxalate is obtained by difference. The method was applied to samples of pulp, process liquors, filtrates, and scale deposits from kraft mills. In kraft mills, considerably higher levels of oxalate were found in the Eop samples compared to those in the brownstock and D0 samples. In both brownstock and Eop samples, oxalate was mainly present in soluble form, whereas the D0-stage contained relatively higher levels of insoluble oxalate.

Desorption electrospray ionization mass spectrometry: Imaging drugs and metabolites in tissues

Ambient ionization methods for MS enable direct, high-throughput measurements of samples in the open air. Here, we report on one such method, desorption electrospray ionization (DESI), which is coupled to a linear ion trap mass spectrometer and used to record the spatial intensity distribution of a drug directly from histological sections of brain, lung, kidney, and testis without prior chemical treatment. DESI imaging provided identification and distribution of clozapine after an oral dose of 50 mg/kg by: i) measuring the abundance of the intact ion at m/z 327.1, and ii) monitoring the dissociation of the protonated drug compound at m/z 327.1 to its dominant product ion at m/z 270.1. In lung tissues, DESI imaging was performed in the full-scan mode over an m/z range of 200-1100, providing an opportunity for relative quantitation by using an endogenous lipid to normalize the signal response of clozapine. The presence of clozapine was detected in all tissue types, whereas the presence of the N-desmethyl metabolite was detected only in the lung sections. Quantitation of clozapine from the brain, lung, kidney, and testis, by using LC-MS/MS, revealed concentrations ranging from 0.05 microg/g (brain) to a high of 10.6 microg/g (lung). Comparisons of the results recorded by DESI with those by LC-MS/MS show good agreement and are favorable for the use of DESI imaging in drug and metabolite detection directly from biological tissues.

Cyclic Flow Injection Analysis with Spectrophotometric Detection for Assay of Acidity in Fruit Juices and Soft Drinks

A single-line flow system, through which a reagent carrier stream is circulated, is proposed for the spectrophotometric determination of acidity (expressed as citric acid content) in fruit juices and soft drinks. The reagent carrier solution consists of pH indicator (Methyl Orange, MO) and sugar (sucrose) in an acetate buffer solution. The method is based on the acid-base neutralization detecting the color change of MO. The resulting solution, after passing through a flow through cell, returns to the reservoir and reused repeatedly. Sucrose is added in the reagent carrier solution to compensate both the differences in refractive index and viscosity between the reagent carrier solution and the sample solution, which make the sample injection directly without any dilution process. Several parameters were optimized, resulting in a simple, fast, and ready constructed acidity analyzer. Fruits juices and soft drinks could be analyzed without any prior chemical treatment. Among several organic acids, citric acid is the major acid in fruit juices. It is frequently added to the industrial drinking derivatives to keep quality and flavor of products constant. The acidity is determined routinely during the processing of drinking products. It is expressed usually as citric acid content. Commonly used techniques for this analysis is titration with the standard base(1). Normally all batch titrations involve quite high volume of reagents consumption and manually operations which are subjected to time consuming and personal error. Therefore, an on-line, near real time acidity analyzer is very desirable. Flow injection analysis (FIA) is widely accepted as an analytical technique capable to perform rapid analysis, and offers many advantages over batch titration (2-4). For the assay of acidity in fruit juices, several procedures (5-7) based on the flow injection method have been proposed employing mixing chamber or variation in reagent flow rate, using spectrophotometry or potentiometry as detection techniques. Imato and Ishibashi reported the spectrophotometric FIA determination of strong acids and bases using a pH indicator and buffer solution (8,9). This method is excellent because the estimation of end point is not necessary. The calibration graph can be constructed from the peak heights (absorbances) of the standard solutions of various concentrations. We developed this method into a cyclic FIA for the determination of strong acids and bases, where the reagent carrier solution was circulated and reused repeatedly (10). Recently we found this cyclic FIA was applicable to citric acid determination in a similar manner as above. In quality control, actual sample analysis without any prior chemical treatment should be desirable in order to decrease sample handling steps while also saving time of analysis. These facilities can be provided by exploiting the direct determination with the simplest manifold. This paper therefore describes the

Desensitization of GSTF8 Induction by a Prior Chemical Treatment Is Long Lasting and Operates in a Tissue-Dependent Manner

The Arabidopsis (Arabidopsis thaliana) GSTF8 gene is a member of the glutathione S-transferase (GST) family whose expression is induced by defense signals, certain chemical stresses, and some pathogens. Here, we have used transgenic plants and an in vivo imaging system to demonstrate that GSTF8 expression is subject to a distinct desensitization phenomenon because prior chemical treatment significantly reduces reactivation of the GSTF8 promoter by hydrogen peroxide, auxin, and salicylic acid. A GSTF8 null line had similar desensitization properties to wild type, demonstrating that GSTF8 protein levels are not responsible for desensitization. The resulting refractory period is unusually long lasting, with full recovery taking 4 d. Expression of the GSTF8 promoter following a second treatment occurred predominantly in newly formed tissue at the root tip, suggesting that desensitization is lost upon cell division. Expression of the endogenous GSTF8 gene and another GST gene, GSTF6, is also desensitized following treatment with hydrogen peroxide. The desensitization phenomenon can be activated by a very low concentration of inducer that is not sufficient to activate the GSTF8 promoter. These results demonstrate that activation of the GSTF8 promoter is not essential for eliciting desensitization. A key promoter sequence within the GSTF8 gene, the ocs element, is also affected by desensitization. Treatment with a phosphatase inhibitor prevents desensitization of GSTF8 expression and ocs element activity, suggesting that dephosphorylation of one or more proteins is required for desensitization to occur.

Novel method for cell immobilization and its application for production of organic acid

The aim was to develop a novel and simple technique for the entrapment of fungal hyphae. A novel immobilization technique was developed by using a structural fibrous network (SFN) of papaya wood as an immobilizing matrix. The technique is simple and a stable entrapment was achieved simply by inoculating the Aspergillus terreus hyphae within culture medium containing SFN pieces for 3 days, without any prior chemical treatment. Results show that SFN has no detrimental effect both on growth and bioactivity of fungi. A 23.5% increase in the itaconic acid production by SFN-immobilized A. terreus was noted when compared with free biomass. SFN-immobilized fungal biomass retained 95% itaconic acid productivity for five repeated batch cycles, 7 days each, without any disintegration/release of hyphae in the production medium. This is the first report on the use of SFN, a structural material, as an immobilizing matrix for the entrapment of any kind of microbial biomass and its application in organic acid. The low cost of SFN and simplicity of the technique applied for immobilization of fungal hyphae within/onto SFN make its use ideal for the immobilization of fungal biomass to produce commercially valuable products.

An Automatic Spectrophotometric Titration Procedure for Ascorbic Acid Determination in Fruit Juices and Soft Drinks Based on Volumetric Fraction Variation

A spectrophotometric flow titration procedure for ascorbic acid in fruit juices and soft drinks based on volumetric fraction variation employing a reaction with 2,6-dichloroindophenol is described. A flow network was designed to implement the multicommutation process and a set of microcomputer controlled three-way solenoid valves was employed to handle the insertion of the titrand and titrant solutions into the analytical path. All the steps involved in the titration procedure were carried out automatically without any operator assistance. Fruit juices and soft drinks could be analyzed without any prior chemical treatment. Accuracy was assessed by comparing results with those obtained by the reference method (AOAC). No significant differences at 95% confidence level were observed. Other profitable features were achieved such as a percentual standard deviation of results of 1.1% (n = 5) for a typical juice sample containing 1.2 mmol L–1 ascorbic acid, a low sample consumption (6 μL per run), and an analytical throughput ranging from 5 to 30 determinations per hour for sample concentrations ranging from 0.6 to 6.0 mmol L–1.