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Due to their chemical and physical properties, rare earth elements (REEs) are essential in modern applications such as energy conversion or IT technology. The increasing demand for these elements leads to strong incentives for REE recovery and induces the exploration of new, alternative sources for REEs. Accessing REEs from clay minerals, in our case kaolinite, by an elution process is a promising method. The present study investigates the potential application of REE recovery through elution with different mineral acids (HNO3, H2SO4, and HCl) in a microwave process. The material used in this study—residues from an industrial kaolin production process—contained 2.47 g/kg REEs which is a significant amount for REE recovery. The ability of various mineral acids to solubilize metals was studied to assess the REE content of this residual resource. Around 1.87 g/kg of REEs was eluted from industrial kaolinite residues in hydrochloric acid, 1.71 g/kg in sulfuric acid, and 1.13 g/kg in nitric acid. [ABSTRACT FROM AUTHOR]

Elevated carbon dioxide (eCO2) and rising temperatures will have far‐reaching effects on global plant‐insect interactions, yet their implications for future biological control programs are not fully understood. Studies have shown that elevated CO2 will affect insect feeding guilds differently and these responses can be predicted with some confidence. Water hyacinth, Pontederia crassipes Mart. (Pontederiaceae), is a native and representative species of the Del Plata wetlands (Argentina) that invades outside of its native environment. It is considered one of the world's worst aquatic weeds and a target for biological control. In this study, water hyacinth plants were grown under two CO2 concentrations – current (400 p.p.m.) or elevated (800 p.p.m.) –, with and without two biocontrol agents representing different feeding guilds, the leaf‐chewing Cornops aquaticum Brüner (Orthoptera: Acrididae) and the phloem‐feeding Megamelus scutellaris Berg (Hemiptera: Delphacidae). Under eCO2 concentration, photosynthetic rate, total dry weight, and relative growth rate of P. crassipes acclimated to eCO2 conditions and plants showed very little CO2 fertilization response in eutrophic water. Insect herbivory varied depending on feeding guilds at eCO2; however, P. crassipes growth responses increased when exposed to insect herbivory. Chewing herbivory by C. aquaticum was consistent across CO2 conditions, whereas the feeding by M. scutellaris increased substantially at eCO2. These results indicate that successful biological control of P. crassipes under conditions of elevated CO2 might rely on phloem‐feeding insects, with chewers playing a lesser role. [ABSTRACT FROM AUTHOR]

Systems engineering activities in the concept and development phases have evolved continuously for decades. The deployment of digital thread, digital engineering, MBSE approaches, and modeling and simulation techniques have driven part of this evolution. Despite this trend, requirements are still largely textual and expressed in natural language, and requirements engineering activities are still often document‐based. However, model‐based requirements‐engineering approaches have emerged in recent years and have demonstrated significant benefits, including improved requirements quality, less ambiguity, and early and efficient verification and validation. The goal of this paper is to present the current outcomes and perspectives of setting up an Integrated Digital Requirements Engineering approach as developed within our company. This approach seeks to optimize usability and maximize benefits to support end‐to‐end V&V activities while fully integrating into MBSE workflows. [ABSTRACT FROM AUTHOR]

Iron reduction and sulfate reduction often occur simultaneously in anoxic systems, and where that is the case, the molar ratio between the reactions (i.e., Fe/SO42− reduced) influences their impact on water quality and carbon storage. Previous research has shown that pH and the supply of electron donors and acceptors affect that ratio, but it is unclear how their influences compare and affect one another. This study examines impacts of pH and the supply of acetate, sulfate, and goethite on the ratio of iron to sulfate reduction in semi‐continuous sediment bioreactors. We examined which parameter had the greatest impact on that ratio and whether the parameter influences depended on the state of each other. Results show that pH had a greater influence than acetate supply on the ratio of iron to sulfate reduction, and that the impact of acetate supply on the ratio depended on pH. In acidic reactors (pH 6.0 media), the ratio of iron to sulfate reduction decreased from 3:1 to 2:1 as acetate supply increased (0–1 mM). In alkaline reactors (pH 7.5 media), iron and sulfate were reduced in equal proportions, regardless of acetate supply. Secondly, a comparison of experiments with and without sulfate shows that the extent of iron reduction was greater if sulfate reduction was occurring and that the effect was larger in alkaline reactors than acidic reactors. Thus, the influence of sulfate supply on iron reduction extent also depended on pH and suggests that iron reduction grows more dependent on sulfate reduction as pH increases. Our results compare well to trends in groundwater geochemistry and provide further evidence that pH is a major control on iron and sulfate reduction in systems with crystalline (oxyhydr)oxides. pH not only affects the ratio between the reactions but also the influences of other parameters on that ratio. [ABSTRACT FROM AUTHOR]

Methanogenesis and iron reduction play major roles in determining global fluxes of greenhouse gases. Despite their importance, environmental factors that influence their interactions are poorly known. Here, we present evidence that pH significantly influences the balance between each reaction in anoxic environments that contain ferric (oxyhydr)oxide minerals. In sediment bioreactors that contained goethite as a source of ferric iron, both iron reduction and methanogenesis occurred but the balance between them varied significantly with pH. Compared to bioreactors receiving acidic media (pH 6), electron donor oxidation was 85% lower for iron reduction and 61% higher for methanogenesis in bioreactors receiving alkaline media (pH 7.5). Thus, methanogenesis displaced iron reduction considerably at alkaline pH. Geochemistry data collected from U.S. aquifers demonstrate that a similar pattern also exists on a broad spatial scale in natural settings. In contrast, in bioreactors that were not augmented with goethite, clay minerals served as the source of ferric iron and the balance between each reaction did not vary significantly with pH. We therefore conclude that pH can regulate the relative contributions of microbial iron reduction and methanogenesis to carbon fluxes from terrestrial environments. We further propose that the availability of ferric (oxyhydr)oxide minerals influences the extent to which the balance between each reaction is sensitive to pH. The results of this study advance our understanding of environmental controls on microbial methane generation and provide a basis for using pH and the occurrence of ferric minerals to refine predictions of greenhouse gas fluxes. [ABSTRACT FROM AUTHOR]

Abstract: Relevant for engineering a wide range of technological systems, Property Model Methodology (PMM) is applied in this paper to the development process of a helicopter function in the frame of the ARP4754A/ED79A. After a short presentation of the method, the case study is presented: “to retract and to extend airborne the landing gear system”. Then, each stage of the PMM development process is illustrated by examples from the case study: (1) Modeling the top level requirements specification, (2) Validating the requirements specification by proof and simulation, (3) Modeling the architectural design, Refining the top level requirements into requirements specified to the different subsystems contributing to the function and Modeling the terminal subsystems detailed designs (4) Validating the requirements specified to the contributing subsystems by proof or simulation, (5) Verifying the design models by simulation and finally (6–8) Verifying physical implementations by test on the basis of all validation and verification scenarios accumulated throughout the development. At end, lessons learnt and industrial perspectives are summarized highlighting how PMM is a methodology adapted to the challenges facing to systems engineering by the globalization of development processes and showing how PMM can provide a powerful conceptual framework to support digital continuity within globalized Design Organizations. Modeling, simulation, proof and test generation activities are supported by the MATLAB and Simulink products. [ABSTRACT FROM AUTHOR]

Glucosylceramides (GlcCer), glucose-conjugated sphingolipids, are major components of the endomembrane system and plasma membrane in most eukaryotic cells. Yet the quantitative significance and cellular functions of GlcCer are not well characterized in plants and other multi-organ eukaryotes. To address this, we examined Arabidopsis lines that were lacking or deficient in GlcCer by insertional disruption or by RNA interference ( RNAi) suppression of the single gene for GlcCer synthase ( GCS, At2g19880), the enzyme that catalyzes GlcCer synthesis. Null mutants for GCS (designated ' gcs-1') were viable as seedlings, albeit strongly reduced in size, and failed to develop beyond the seedling stage. Heterozygous plants harboring the insertion allele exhibited reduced transmission through the male gametophyte. Undifferentiated calli generated from gcs-1 seedlings and lacking GlcCer proliferated in a manner similar to calli from wild-type plants. However, gcs-1 calli, in contrast to wild-type calli, were unable to develop organs on differentiation media. Consistent with a role for GlcCer in organ-specific cell differentiation, calli from gcs-1 mutants formed roots and leaves on media supplemented with the glucosylated sphingosine glucopsychosine, which was readily converted to GlcCer independent of GCS. Underlying these phenotypes, gcs-1 cells had altered Golgi morphology and fewer cisternae per Golgi apparatus relative to wild-type cells, indicative of protein trafficking defects. Despite seedling lethality in the null mutant, GCS RNAi suppression lines with ≤2% of wild-type GlcCer levels were viable and fertile. Collectively, these results indicate that GlcCer are essential for cell-type differentiation and organogenesis, and plant cells produce amounts of GlcCer in excess of that required for normal development. [ABSTRACT FROM AUTHOR]

The antiinflammatory effects of ethanol and aqueous extracts from Drosera rotundifolia and from Drosera madagascariensis were compared in vivo in the HET-CAM assay. Both extracts from D. rotundifolia and the ethanol extract from D. madagascariensis showed remarkable efficacy at doses of 500 µg/pellet. The inhibition of the inflammation by the extracts was stronger than that by 50 µg hydrocortisone/pellet. In contrast, there was only a very weak effect observed at a dose of 500 µg/pellet of the water extract from D. madagascariensis. The chemical analyses of the extracts showed that the effect cannot be attributed to naphthoquinones, but might be due to flavonoids. Ellagic acid obviously plays an important role in the antiangiogenic effect of the Drosera extracts. Copyright © 2005 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

In 1992 Barnett Bank, one of the top 25 banks in the United States, embarked on a redesign of the direct consumer lending process. The redesign involved moving from 32 to two processing centres, and has reduced processing time from three to less than one day. This case study describes Barnett Bank's approach to BPR and managing the process of redesign itself. [ABSTRACT FROM AUTHOR]

The purpose of the research was to examine the part a creative environment plays in creating the foundation for BPR efforts. A comparison between creative environments in US and Japanese companies was used to address the research question. The creative environment of each company was examined by looking at four categories of factors--people, process, output, and environment. These categories were used to organize and systematically analyze the data. In general, the researcher found that Japanese companies tend to adopt incremental business process improvement (BPI) rather than BPR. BPI is a way of life. Emphasis is placed on the 'group' rather than the individual. Since the group is emphasized, individual innovation and creativity is not generally nurtured by management. However, some Japanese companies are beginning to see the value of individual creativity. They are starting creativity training programmes for key employees. Nevertheless, it will take some time before a paradigm of individuality is generally accepted. Since US companies want to change quickly and radically to become more competitive, many are experimenting with BPR. However, a critical success factor of BPR is teamwork and cooperation. Although US companies have historically been very individualistic, teaming and nurturing is beginning to make its way into the culture of many organizations. Successful BPR hinges on changing to an environment conducive to change. Organizations that understand the importance of a change-oriented environment will have the best chance of success. It appears that US and Japanese companies are converging on similar paradigms of work. US companies are moving from "rugged" individualism to cooperation and teamwork. Japanese companies are moving from a group consensus paradigm to one that encourages individual creativity. Although US companies have a long way to go, it might be more difficult for Japanese companies. The culture in Japan is much more homogeneous. In addition, free flow of ideas has not been a part of the Japanese culture. Whether or not companies in the US embrace teamwork and individual creativity, the basic culture of the US has always been democratic and has encouraged free speech. [ABSTRACT FROM AUTHOR]

ABSTRACT "What's right with unemployment insurance" by far outweighs "What's wrong." There are, nevertheless, many flaws in the program--in philosophy, in benefits, in taxes, in administration. Most important is the need for consensus concerning primary goals. There is still no generally-accepted philosophy concerning the proper place and purpose of unemployment insurance in our economic system. Many workers currently exempt from coverage should be protected. Qualifying requirements for benefit eligibility, as well as disqualifying provisions, should be reexamined. Minimum and maximum weekly benefit amounts and potential duration provisions indicate inherent philosophies which are inconsistent and inequitable, which yield more generous benefits to unemployed secondary workers than to unemployed heads of families. Changes should relate qualifying employment and earnings, by sex, to minimum and maximum benefits and duration, in fixed proportions rather than in fixed amounts. Payroll tax bases vary considerably. Their impact among different industries is widely divergent. A supplemental flat-rate employee tax should help finance more adequate benefits. Pending agreement on primary goals, no practical solution to federal-state administrative problems can be suggested. Thereafter, however, authority and responsibility and costs should be fairly and dearly allocated between the federal government and the states. This would contribute to a much better partnership, program, and public image. [ABSTRACT FROM AUTHOR]

Chronic disorders such as haemophilia and yon Willebrand disease can rob people of a feeling of control over their lives. Added to this is often a feeling of confusion or intimidation when dealing with the healthcare system. People may begin to feel like victims of their disorders and of the healthcare system. The healthcare system defines people who are in receipt of care as patients. The word patient comes from the Latin word patiens, which means to suffer, endure, allow, permit or undergo. Even the term implies a sense of victimization. People who become partners in their care and view the receipt and delivery of healthcare as a service wherein they are the consumer and the doctor or clinician is the provider, will feel more in control and will likely have better outcomes than people who assume the more traditional role of 'patient'. [ABSTRACT FROM AUTHOR]

N-methylated tryptamines, such as the hallucinogenic natural products, psilocybin and N,N-dimethyltryptamine (DMT), are gaining interest from the medical community due to their potential as next generation treatments for mental health disorders. The clinical relevance of these compounds has driven scientists to develop biosynthetic production routes to a number of tryptamine drug candidates, and efforts are ongoing to expand and further develop these biosynthetic capabilities. To that end, we have further characterized the substrate preferences of two enzymes involved in tryptamine biosynthesis: TrpM, a tryptophan N-methyltransferase from Psilocybe serbica, and PsiD, the gateway decarboxylase of the psilocybin biosynthesis pathway. Here, we show that TrpM can N-methylate the non-native amino acid substrate, 4-hydroxytryptophan, a key intermediate in the Escherichia coli-based recombinant psilocybin biosynthesis pathway. However, the ability to incorporate TrpM into a functional psilocybin biosynthesis pathway was thwarted by PsiD's inability to use N,N-dimethyl-4-hydroxytryptophan as substrate, under the culturing conditions tested, despite demonstrating activity on N-methylated and 4-hydroxylated tryptophan derivatives individually. Taken together, this work expands upon the known substrates for TrpM and PsiD, further increasing the diversity of tryptamine biosynthetic products., (© 2024 The Author(s). Biotechnology Progress published by Wiley Periodicals LLC on behalf of American Institute of Chemical Engineers.)

Butyl butyrate is a short-chain fatty acid ester (C8) with a fruity aroma. It has broad prospects in the fields of foods, cosmetics and biofuels. At present, butyl butyrate is produced by chemical synthesis in the industry, but it is highly dependent on petroleum-based products. The growing concerns regarding the future scarcity of fossil fuels have been strongly promoted the transition from traditional fossil fuels and products to renewable bioenergy and biochemicals. Therefore, it is necessary to develop a green biochemical technology to replace traditional petroleum-based materials. In recent years, microorganisms such as Escherichia coli and Clostridium have been engineered to serve as cell factories for the sustainable one-pot production of short-chain fatty acid esters, including butyl butyrate. This opinion highlights the recent development in the use of lipases and alcohol acyltransferases (AATs) for butyl butyrate production in microbial fermentation, as well as future perspectives., (© 2024 The Author(s). Microbial Biotechnology published by John Wiley & Sons Ltd.)

Parametric optimization always plays important roles in bioengineering systems to obtain a high product yield under the proper conditions. The parametric conditions of lactic acid production by homologous batch fermentation of Lactobacillus pentosus cells was optimized by the Box-Behnken design. The highest l-lactic acid yield was obtained as 0.836 ± 0.003 g/g glucose with the productivity of 0.906 ± 0.003 g/(L × H) under the optimum conditions of 34.7 °C, pH 6.2, 148 rpm agitation speed, and 9.3 g/L nitrogen source concentration determined by quadratic response surface with high accuracy. The adequate kinetic models of cell growth rate, lactic production rate, and glucose consumption rate were also established to describe the fermentation behavior of L. pentosus cells with the correlation coefficients of 09985, 0.9990, and 0.9989, respectively., (© 2020 International Union of Biochemistry and Molecular Biology, Inc.)

Lignocellulose, one of the most abundant renewable sources of sugar, can be converted into bioenergy through hydrolysis of cellulose and hemicellulose. Due to its renewability and availability in large quantities, bioenergy is considered as a possible alternative to fossil energy and attracts the attention of the world with increased concerns about environmental protection and energy crisis. The depolymerization of cellulosic substrate to monomer is the rate-limiting step in the bioconversion of lignocellulose by cellulolytic microbes. Cellulosome, a multienzyme complex from anaerobic cellulolytic bacteria, can efficiently degrade the cellulosic substrates. Previous studies have shown that the reconstitution of cellulosome in vitro and its heterologous expression or display on the cell surface can help to solve the low yield problem of cellulosome in cellulolytic bacteria. This paper reviews the research progress in the reconstitution of cellulosome as well as its application in biorefinery, including the construction of cellulosome as well as different methods for cellulosome reconstitution and its surface display. This review will promote the understanding of cellulosome and its reconstitution., (© 2019 International Union of Biochemistry and Molecular Biology, Inc.)

When using a combination of pre-extraction and chemical pulping, a high yield of sugar recovery and minimal negative effect on the subsequent pulping step are expected. In this work, the P factor was utilized to investigate the effect of auto-hydrolysis severity on sugar recovery, removal of the main component, and impact on the kraft pulping of acacia wood chips. Using a P factor of 235, 84.34% of the polysaccharides in 14.05 g L -1 of dissolved sugars could be obtained. In addition, the soluble sugars were easily separated with a recovery yield of 3.54 g ·L -1 and Mw of 4,690 g mol -1 by direct precipitation using organic solvents. However, a maximum of 22.14 g L -1 of dissolved sugars was obtained with approximately 72.53% polysaccharides and Mw of 2,198 g mol -1 for a P factor of 601. Moreover, nearly 50% of the degraded carbohydrates remained in the auto-hydrolyzed wood chips. The decrease in the mass of pentosan, holocellulose, and klason lignin was 62, 30, and 8.76%, respectively. With intensifying severity, the screened yield and viscosity of pulps decreased markedly, whileas the Kappa number increased. No significant differences were observed in the morphology of the resultant fibers. Moreover, there was a decrease in the physical strength of the pulps due to the loss of the intrinsic strength of the pulp fibers, which in turn resulted from the cellulose damage. The combustion performance of the resultant pulping black liquor is improved due to the higher lignin content., (© 2019 American Institute of Chemical Engineers.)

This study investigated the impact of biomass-based fly ash (FA) pretreatment on the biodegradability of a thermomechanical pulping spent liquor (TMPL) in an aerobic system. In this study, FA was mixed with TMPL under the conditions of 6 wt.% based on TMPL, 25°C and 10 h, which removed a part of recalcitrant organic materials and resulted in 68.0, 40.0, 60.1, 81.2 and 48.3% reductions in chemical oxygen demand (COD), biochemical oxygen demand (BOD), total organic carbon (TOC), lignin and sugar, respectively. FA-pretreated TMPL pressate (FA-TMPL) was biologically treated in an aerobic system of sequencing batch reactor (SBR). The performance of the biological treatment with and without FA pretreatment was studied in two parallel SBRs over three months. The combination of FA and biological treatments removed 97.3% of COD, 98.3% of BOD, 96.3% of lignin, 99.5% of sugar, and 98.1% of TOC. Without FA pretreatment, the biological system removed 87.3% of COD, 89% of BOD, 81.6% of lignin, 98.6% of sugars, and 90.5% of TOC. The results also confirmed that the settling ability of sludge, which was indicated as a sludge volume index, was reduced from 109.3 mL/g to 53.5 mL/g. In addition, the advantages of using FA pretreatment in aerobic systems were discussed in detail. © 2017 American Institute of Chemical Engineers Biotechnol. Prog., 34:370-378, 2018., (© 2017 American Institute of Chemical Engineers.)

The main purpose of this study is to explore the sulfation of xylan to produce an anionic flocculant, sulfated xylan, for removing ethyl violet dye from simulated dye solutions. In this work, xylan was sulfated with chlorosulfonic acid in N, N-dimethylformamide solvent and the reaction conditions were optimized using a response surface methodology. It was observed that the maximum degree of substitution of 1.1 was obtained for sulfated xylan under the conditions of 3.71 chlorosulfonic acid/xylan molar ratio, 70°C and 7 h reaction time. The resulting sulfated xylan had a charge density of -3.12 mmol/g and molecular weight (M w ) of 22,300 g/mol. Furthermore, elemental and thermogravimetric analyses, Fourier transform infrared spectroscopy and proton nuclear magnetic resonance ( 1 H-NMR) confirmed the sulfation of xylan. The application of sulfated xylan as a flocculant for decolorizing the simulated ethyl violet dye wastewater was studied. The results indicated that 97% of dye was removed from 50 mg/L dye solution at the sulfated concentration of 175 mg/L and pH 9, but unmodified xylan was ineffective in flocculating and removing dye segments. © 2018 American Institute of Chemical Engineers Biotechnol. Prog., 34:529-536, 2018., (© 2018 American Institute of Chemical Engineers.)

Among the protease-producing bacterial strains isolated from deep-sea sediments, SWJS2 was finally selected and identified as genus Exiguobacterium. Plackett-Burman and orthogonal array designs were applied to optimize the fermentation conditions, and the results are as follows: Glucose 5g, yeast extract 15g, glycerin 2g and CaCl2 ⋅2H2 O 0.5 g dissolved in 1 L artificial seawater; temperature 25 °C, original pH 7, inoculum rate 2%, seed age 12 H, loading volume 25 mL (250-mL Erlenmeyer flask), shaking speed 150 rpm, and fermentation time 44 H. The protease activity production was improved from about 80 to 660 U/mL under the optimized parameters. The protease was purified fourfold with specificity activity of 30,654.1 U/mg protein and a total yield of 16.2%. The protease exhibited the maximum activity at 40-45 °C and pH 7. Moreover, the enzyme activity was found to be inhibited by Cu(2+) , Ba(2+) , Cd(2+) , Hg(2+) , and Al(3+) at 5 mM, whereas it can be increased by Mg(2+) , Mn(2+) , and Ca(2+) at 0.5-5 mM. The enzyme was totally inactivated by 1 or 5 mM ethylenediaminetetraacetic acid but not by phenylmethanesulfonyl fluoride, tyrpsin inhibitor from Glycine max (STI), benzamidine, 5,5'-dithio-bis-(2-nitro benzoic acid), or pepstatin A, suggesting that it belonged to metalloprotease., (© 2015 International Union of Biochemistry and Molecular Biology, Inc.)

Potato residue is vastly produced in the food industry but it is landfilled. This article describes the treatment of purified cellulose derived from potato residues by a high pressure homogenizer to produce nano-fibrillated cellulose (NFC), which was then oxidized by sodium periodate to prepare dialdehyde nano-fibrillated cellulose (DANFC). The produced NFC and DANFC were characterized by a scanning electron microscope (SEM) and Fourier transform infrared spectroscopy (FTIR). The orthogonal experiment was induced to obtain the maximum degree of oxidation (DO) on DANFC. The results indicated that the optimal conditions were 40°C and pH 3. Alternatively, the isotherm and kinetic studies for the adsorption of creatinine on DANFC with different DOs (70.5 and 88.8%) were investigated, and the experimental results fitted well into Freundlich isotherm model and pseudo second-order kinetic model. The maximum adsorption capacities of DANFCs with the DO of 70.55 and 88.85% were 6.7 and 17.2 mg g(-1) , respectively, which were achieved under the conditions of 37°C and initial creatinine concentration of 100 mg L(-1)., (© 2015 American Institute of Chemical Engineers.)

Enzymatic synthesis of ascorbyl undecylenate, an unsaturated fatty acid ester of ascorbic acid, was reported with biomass-derived 2-methyltetrahydrofuran (MeTHF) as the cosolvent. Of the immobilized lipases tested, Candida antarctica lipase B (CAL-B) showed the highest activity for enzymatic synthesis of ascorbyl undecylenate. Effect of reaction media on the enzymatic reaction was studied. The cosolvent mixture, t-butanol-MeTHF (1:4, v/v) proved to be the optimal medium, in which not only ascorbic acid had moderate solubility, but also CAL-B showed a high activity, thus addressing the major problem of the solvent conflict for dissolving substrate and keeping satisfactory enzyme activity. In addition, the enzyme was much more stable in MeTHF and t-butanol-MeTHF (1:4) than in previously widely used organic solvents, t-butanol, 2-methyl-2-butanol, and acetone. The much higher initial reaction rate in this cosolvent mixture may be rationalized by the much lower apparent activation energy of this enzymatic reaction (26.6 vs. 38.1-39.1 kJ/mol) and higher enzyme catalytic efficiency (Vmax /Km , 8.4 vs. 1.3-1.4 h(-1) ). Ascorbyl undecylenate was obtained with the yields of 84-89% and 6-regioselectivity of >99% in t-butanol-MeTHF (1:4) at supersaturated substrate concentrations (60 and 100 mM) after 5-8 h., (© 2014 American Institute of Chemical Engineers.)

Biobleaching of kraft pulp is a possible application of laccase, but it has not been described in detail for complete industrial bleaching sequences yet. Therefore, in this work, the biobleaching of Eucalyptus globulus kraft pulp was performed using a modified industrial totally chlorine-free sequence. The modification consisted in the substitution of an enzymatic delignification stage, based on the application of laccase from Trametes villosa, for the first alkaline extraction one. The enzymatic stage was performed with several synthetic and natural mediators, namely 1-hydroxybenzotriazole (HBT), violuric acid (VA), methyl syringate, and syringaldehyde. Several pulp properties were analyzed after each stage of the bleaching process--kappa number, ISO brightness, viscosity, and optical properties of CIEL*a*b* system. The new biobleaching sequence improved the pulp properties, in comparison to the conventional bleaching sequence, if HBT or VA was used as mediators. VA was selected as the best mediator of those tested and the effect of its concentration in the enzymatic stage was subsequently studied. Reducing the initial concentration by 30%, the same pulp quality was obtained, but if the reduction attained 60%, an important decrease in pulp integrity was detected. The modified bleaching sequence could improve the bleached pulp properties (kappa number 10%, ISO brightness 1%, and viscosity 5%) in comparison to the mill sequence., (Copyright © 2012 American Institute of Chemical Engineers (AIChE).)

The prehydrolysis liquor (PHL) of the kraft-based dissolving pulp production process contains various amounts of hemicelluloses that can be utilized in the production of value-added products. In this work, a new process was proposed for removing the inhibitors of PHL via employing a flocculation concept to facilitate the utilization of hemicelluloses. Lignin, lignocelluloses/cationic polymer complexes, and possibly ethanol are the main products of this process. This process has been experimentally evaluated with an industrially produced PHL and cationic polymers. The results showed that 16% of lignin, 19% of acetic acid, 43% of furfural, and insignificant amount of sugars were removed from PHL via pretreating PHL with acid and lime at pH 7. Furthermore, by adding 0.4-0.5 mg g(-1) polydiallyldimethylammonium chloride (PDADMAC) or chitosan to the pretreated PHL, 12-14% acetic acid, 40-50% furfural, 5-6% monomeric sugars, and 25% oligomeric sugars were removed from the PHL. The complexes made from these components may be applied as organic fillers in various industries. Alternatively, by adding 1.2 or 1.4 mg g(-1) PDADMAC or chitosan to the pretreated PHL, 30 or 35% of lignin was removed, respectively, which induced complexes that could be used as a fuel source. The composition of the complexes formed was also determined in this work., (Copyright © 2012 American Institute of Chemical Engineers (AIChE).)

The modular endoglucanase Cel9B from Paenibacillus barcinonensis is a highly efficient biocatalyst, which expedites pulp refining and reduces the associated energy costs as a result. In this work, we set out to identify the specific structural domain or domains responsible for the action of this enzyme on cellulose fibre surfaces with a view to facilitating the development of new cellulases for optimum biorefining. Using the recombinant enzymes GH9-CBD3c, Fn3-CBD3b, and CBD3b, which are truncated forms of Cel9B, allowed us to assess the individual effects of the catalytic, cellulose binding, and fibronectin-like domains of the enzyme on the refining of TCF kraft pulp from Eucalyptus globulus. Based on the physico-mechanical properties obtained, the truncated form containing the catalytic domain (GH9-CBD3c) has a strong effect on fibre morphology. Comparing its effect with that of the whole cellulase (Cel9B) revealed that the truncated enzyme contributes to increasing paper strength through improved tensile strength and burst strength and also that the truncated form is more effective than the whole enzyme in improving tear resistance. Therefore, the catalytic domain of Cel9B has biorefining action on pulp. Although cellulose binding domains (CBDs) are less efficient toward pulp refining, evidence obtained in this work suggests that CBD3b alters fibre surfaces and influences paper properties as a result., ((c) 2010 American Institute of Chemical Engineers)

This study demonstrates sulfite pretreatment to overcome recalcitrance of lignocellulose (SPORL) for robust bioconversion of hardwoods. With only about 4% sodium bisulfite charge on aspen and 30-min pretreatment at temperature 180 degrees C, SPORL can achieve near-complete cellulose conversion to glucose in a wide range of pretreatment liquor of pH 2.0-4.5 in only about 10 h enzymatic hydrolysis. The enzyme loading was about 20 FPU cellulase plus 30 CBU beta-glucosidase per gram of cellulose. The production of fermentation inhibitor furfural was less than 20 mg/g of aspen wood at pH 4.5. With pH 4.5, SPORL avoided reactor corrosion problem and eliminated the need for substrate neutralization prior to enzymatic hydrolysis. Similar results were obtained from maple and eucalyptus., ((c) 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2009.)

CAL-B-catalyzed synthesis of different 5'-O-monoester derivatives of 6-azauridine via a one-step highly regioselective enzymatic acylation route was successfully performed for the first time. The effects of some crucial factors on the enzymatic undec-10-enoylation of 6-azauridine were examined. The optimal reaction medium, molar ratio of 6-azauridine to vinyl undec-10-enoate and reaction temperature were found to be anhydrous acetone, 1:3 and 50 degrees C, under which the reaction rate, the substrate conversion and the regioselectivity were 22.3 mM/h, 99.0% and 99.0%, respectively. In addition, the enzyme recognition of acyl donors was investigated. The results showed that the enzyme activity varied widely with different acyl donors owing to the specific structure of the lipase active site and the acyl donors. 5'-O-Monoesters of 6-azauridine were achieved exclusively with all the acyl donors tested., (2009 American Institute of Chemical Engineers)

The effects of xylanase pretreatment of high lignin content softwood (SW) kraft pulp on subsequent pulp treatment with laccase in combination with gallic acid were investigated. Although xylanase pretreatment was ineffective in enhancing the laccase-facilitated biografting of gallic acid to kraft fibers, it was beneficial for subsequent treatment with laccase exclusively. Treating pulp fibers with xylanase followed by laccase provided a collective 25% and 46% increase in dry and wet tensile strength properties, respectively.

A laccase-mediator system (LMS) for biobleaching was applied to a bleached chemical pulp dyed with stilbene dye Direct Yellow 11. Of mediators tested, 2,2'-azinobis(3-ethylbenzthiazoline-6-sulfonate) (ABTS) was found to be more effective than either violuric acid (VA) or N-hydroxybenzotriazole (HBT), which had been shown to be superior to ABTS when bleaching virgin chemical pulp. The laccase-ABTS system removed more than 60% of the color.

Laccase was reacted with gallic acid in the presence of a high-kappa (91) kraft pulp. The result was a modified pulp with 34%, 20%, and 72% improvements in burst, tensile, and wet tensile strength compared to untreated control samples. Fully bleached pulps were not responsive to the laccase treatment, indicating lignin was the major target for the fiber modification. The results indicate that the strength increases were a combined effect of improvements of hydrogen bonding between fibers and creation of phenoxy radical cross-links within the sheet.