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This paper examines the need for innovation in phosphorus fertilizer production. An important area requiring action is the use of sulfuric acid in the wet chemical process (WCP), which is the dominant process in phosphate fertilizer production. About 50 % of the sulfuric acid produced worldwide is used for fertilizers, and ~95 % of the world's fertilizers are based on sulfuric acid. The latter is almost exclusively a by-product of gas and oil production, so the production of conventional P fertilizer is largely dependent on the availability of oil and gas. In addition to rendering P fertilizer production independent of fossil raw materials, energy consumption, CO 2 emissions, phosphogypsum production and water consumption should also be considered. With the example of the PARFORCE process and the Improved Hard Process (IHP), new non-sulfuric acid-based alternatives are discussed with respect to overcoming the drawbacks of the classical WCP by being completely independent of fossil sources, working with renewable energies as the sole energy source, and the option of using seawater instead of fresh water. These new processes adhere to the principles of climate neutrality, zero waste production, low CO 2 footprint, water conservation, renewable energy use, and energy and resource efficiency. This demonstrates what sustainable innovation can look like from a production perspective. The discussion will focus on whether current incentives are sufficient to realize the sustainability innovations discussed., (© 2024 The Authors. ChemSusChem published by Wiley-VCH GmbH.)

Raw mixtures of Rare Earths Elements, REE, recovered by E-waste, were used as catalysts to promote the (stereoselective) synthesis of highly valuable compounds. Y 2 O 3 , the major species that is recovered by the E-waste, can be easily converted into the catalytically active Y(OTf) 3 that is able to efficiently promote the Michael addition of indoles to benzylidene malonates and the stereoselective Diels-Alder cycloaddition between cyclopentadiene and 4-(S)-3 acryloyl 4-tert-butyl 2-oxazolidinone. Additionally, the raw mixtures were immobilissed onto silica and used to construct packed reactors, resulting in values for Productivity and Space-Time Yields that were significantly higher than those of the corresponding batch conversions. Notably, the prepared cartridge employed in the model Michael reaction maintained its catalytic efficiency for more than 4 days of continuous running., (© 2024 The Authors. ChemSusChem published by Wiley-VCH GmbH.)

Considerable evidence links the "Big Five" personality traits (neuroticism, extroversion, conscientiousness, agreeableness, and openness) with depression. However, potential mediating and moderating factors are less well understood. We utilized data from a cross-sectional survey of 3065 German-speaking adults from the D-A-CH region to estimate multivariable-adjusted odds ratios and 95% confidence intervalsbetween personality traits and lifetime prevalence of depression (overall and stratified by sex and age). We further explored proportions mediated by psychosocial factors optimism, empathy, perspective-taking, work-life balance, and interpersonal trust. High levels of neuroticism were associated with more than two-fold higher odds of depression, whereas higher levels of conscientiousness were associated with approximately 30% lower odds of depression. The association with neuroticism persisted in all investigated subgroups; apparently, stronger associations for females and participants aged ≥60 years did not correspond to statistically significant interactions. Overall and across all strata, the association of neuroticism with depression appeared to be mediated in part by the considered psychosocial factors; optimism explained the largest proportion of the association. Our results provide empirical evidence for the dynamic predisposition model. Further investigations of these relationships are warranted in longitudinal data with more precise outcome assessments.

A novel biobased pickering emulsion (PE) material was prepared by the encapsulation of Cyanex 923 (Cy923) into chitosan (CS) to selectively recover rare earth elements (REEs) from the aqueous phase. The preparation of PE was optimized through sequentially applying a 2 3 full factorial design, followed by a 3 3 Box-Behnken design varying the Cy923 content, CS concentration, and pH of CS. The material was characterized by Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), optical microscopy, rheological, compositional, and stability measurements. The resultant material was evaluated in the removal of yttrium by pH influence, nitrate concentration, kinetics, equilibrium isotherms, reusability, and a comparison with liquid-liquid (L-L) extraction and tested in a real scenario to extract Y from a fluorescent lamp powder waste. In addition, the selectivity of PE for REE was investigated with Y/Ca, Gd/Ca, and La/Ni systems. PE extracts REE at 1 ≤ pH ≤ 5 at nitrate concentrations up to 2 mol/L. The kinetics and equilibrium studies showed reaction times <5 min and a maximum sorption capacity of 89.98 mg/g. Compared with L-L extraction, PE consumed 48% less Cy923 without using organic diluents. PE showed a remarkable selectivity for REE in the systems evaluated, showing separation factors of 22.62, 9.35, and 504.64 for the blends Y/Ca, Gd/Ca/Mg, and La/Ni, respectively. PE showed excellent selectivity extracting Y from a real aqueous liquor from the fluorescent lamp powder. PE demonstrates to be an effective and sustainable alternative for REE recovering due to its excellent efficiency in harsh conditions, favorable green chemistry metrics, and use of a biopolymer material in its composition avoiding the use of organic solvents used in L-L extraction.

Interpersonal trust declined worldwide during the COVID-19 pandemic; strategies are needed to restore it. We surveyed 3,065 quota-sampled German-speaking adults residing in the D-A-CH region. Using multinomial logistic regression models and backward elimination for variable selection, we calculated multivariable-adjusted odds ratios (OR) and 95% confidence intervals (95% CIs) to appraise correlates of interpersonal trust using the Interpersonal Trust Short Scale (KUSIV3). Participants with high levels of interpersonal trust (top KUSIV3 tertile (T3)) tended to be older, male, residents of Switzerland, university degree holders, and workers with higher income and work satisfaction (all Pdiff<0.01) compared to those in the lowest KUSIV3 tertile (T1). Optimism was most strongly associated with high interpersonal trust (ORT3vsT1 = 5.75, 95%CI = 4.33-7.64). Also significantly associated with high interpersonal trust were: Having voted in the last national election (for the opposition, OR = 1.39, 95%CI = 1.02-1.89 or the governing party, OR = 1.61, 95%CI = 1.23-2.11) versus non-voters; perspective taking (ORT3vsT1 = 1.46, 95%CI = 1.11-1.91); being more extraverted (ORT3vsT1 = 1.99, 95%CI = 1.53-2.59) and more agreeable (ORT3vsT1 = 1.95, 95% CI = 1.46-2.61); and scoring higher on complexity thinking (ORT3vsT1 = 1.32, 95%CI = 1.01-1.72). Participants scoring significantly lower for interpersonal trust did not regularly participate in religious meetings (OR = 0.61, 95%CI = 0.44-0.84, versus participation at least monthly); were more conscientious (ORT3vsT1 = 0.68, 95%CI = 0.51-0.91) or current smokers (OR = 0.68; 95%CI = 0.53-0.87, versus never smoking); had sleep problems >5 times a week (OR = 0.48; 95%CI = 0.36-0.66, versus none); and scored high on conspiracy belief (ORT3vsT1 = 0.53; 95%CI = 0.41-0.69). Results differed minimally by gender and country. These findings may be helpful in devising targeted strategies to strengthen interpersonal trust and social engagement in European societies, especially during times of crises., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2023 Schernhammer et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

The presented work sets out to investigate the influence of aluminium on the hydrogenation of vanadium by first studying the hydrogenation properties of the V-H system in detail followed by the study of the V-Al-H system. Aluminium was found to have a stabilising effect on vanadium hydride phases. Presumably by functioning as an oxygen getter, aluminium lowers equilibrium pressures and increases hydrogen capacities in respect to the V/H ratio compared to the V-H system. Attempts of the synthesis of the hypothetical V(AlH 4 ) x by metathesis and direct hydrogenation were not successful, suggesting its instability below room temperature at ambient pressure as well as up to 180 bar of hydrogen pressure in the temperature range of 30 to 100 °C.

Neodymium (Nd) is a key rare earth element (REE) needed for the future of incoming technologies including road transport and power generation. Hereby, a sustainable adsorbent material for recovering Nd from the aqueous phase using a residue from the saccharification process is presented. Banana rachis (BR) was treated with cellulases and polyethylene glycol (PEG) to produce fermentable sugars prior to applying the final residue (BR-PEG) as an adsorbent material. BR-PEG was characterized by scanning electron microscopy (SEM), compositional analysis, pH of zero charge (pH pzc ), Fourier transform infrared analysis (FTIR) and thermogravimetric analysis (TGA). A surface response experimental design was used for obtaining the optimized adsorption conditions in terms of the pH of the aqueous phase and the particle size. With the optimal conditions, equilibrium isotherms, kinetics and adsorption-desorption cycles were performed. The optimal pH and particle size were 4.5 and 209.19 μm, respectively. BR-PEG presented equilibrium kinetics after 20 min and maximum adsorption capacities of 44.11 mg/g. In terms of reusage, BR-PEG can be efficiently reused for five adsorption-desorption cycles. BR-PEG was demonstrated to be a low-cost bioresourced alternative for recovering Nd by adsorption.

The recovery and valorization of metals and rare earth metals from wastewater are of great importance to prevent environmental pollution and recover valuable resources. Certain bacterial and fungal species are capable of removing metal ions from the environment by facilitating their reduction and precipitation. Even though the phenomenon is well documented, little is known about the mechanism. Therefore, we systematically investigated the influence of nitrogen sources, cultivation time, biomass, and protein concentration on silver reduction capacities of cell-free cultivation media (spent media) of Aspergillus niger , A. terreus , and A. oryzae . The spent medium of A. niger showed the highest silver reduction capacities with up to 15 μmol per milliliter spent medium when ammonium was used as the sole N-source. Silver ion reduction in the spent medium was not driven by enzymes and did not correlate with biomass concentration. Nearly full reduction capacity was reached after 2 days of incubation, long before the cessation of growth and onset of the stationary phase. The size of silver nanoparticles formed in the spent medium of A. niger was influenced by the nitrogen source, with silver nanoparticles formed in nitrate or ammonium-containing medium having an average diameter of 32 and 6 nm, respectively., Competing Interests: The authors have declared no conflict of interest., (© 2023 The Authors. Engineering in Life Sciences published by Wiley‐VCH GmbH.)

Background: Emergence of new coronavirus variants and waning immunity may necessitate regular COVID-19 vaccine boosters, but empirical data on population willingness for regular vaccination are limited., Methods: In August 2021, we surveyed 3,067 quota-sampled German-speaking adults residing in the D-A-CH region (Germany, Austria, Switzerland). Using multivariable adjusted ordered logistic regression models we calculated odds ratios (OR) and 95% confidence intervals (95% CIs) to assess factors associated with willingness to vaccinate annually against COVID-19., Findings: Among 2,480 participants vaccinated or planning to get vaccinated, 82·4% indicated willingness to receive annual COVID-19 boosters. This willingness was higher in Austria (OR=1·47, 95% CI, 1·19-1·82; p < 0·001) and Germany (OR=1·98, 95% CI, 1·60-2·45; p  < 0·001) versus Switzerland and increased with age. Having voted in the last national election (OR opposition party voters =1·51, 95% CI=1·18-1·92; p  = 0·001 and OR governing party voters =1·57, 95% CI=1·28-1·93; p  < 0·001, versus non-voters) and not regularly participating in religious meetings (OR=1·37, 95% CI=1·08-1·73; p  = 0·009, versus participation at least monthly) were significantly associated with willingness to vaccinate, as was partial (OR=1·97, 95% CI=1·43-2·72; p  < 0·001) or total (OR=5·20, 95% CI=3·76-7·19; p  < 0·001) approval of COVID-19 mitigation measures (versus non-approval). By country, Austrians showed the strongest association of voting behavior and mitigation measure approval with willingness to vaccinate., Interpretation: Targeted promotion programs informed by political and religious engagement and mitigation measure approval are needed to increase willingness to receive regular COVID-19 boosters., Funding: Medical University of Vienna, Department of Epidemiology, Danube University Krems, Department for Knowledge and Communication Management; Austrian Society of Epidemiology., Competing Interests: JW received funding from the Austrian Society of Epidemiology. BMB reports that her institution (Brigham and Women's Hospital, Boston, MA, USA) received research grant funding from the US National Institutes of Health and from the American Institute for Cancer Research (AICR) to support research projects that she leads and that are unrelated to this manuscript (cancer etiology studies). She is also has been an unpaid member of the Scientific Advisory Panel of the Oliver Foundation (Key Biscayne, FL) since 2015 to help guide their work on pediatric cancer prevention. IS reports royalties from book publications and Honoraria (about 2-3 times per year) for invited lectures not exceeding on the average € 1000 per year. MB reports to have received funding from the German Federal Ministry of Science and Education, German Federal Ministry of Economic affairs, Saxonian Ministry of Science and the Arts, EU H-2020 and honoraria for reviews from European public funding organizations. MB also reports patents DE102021115850.8; DE102020134133.4; DE102020107138.8; DE102018105449.1; and he is Member of the Executive committee of the Saxonian Academy of Sciences, Secretary General for the technical sciences in the Saxonian Academy of Sciences, Head of DECHEMA expert group “Raw Materials”, as well as Director of Recycling unit at Fraunhofer Institute for Ceramic Technologies and Systems IKTS; Fraunhofer Technology Center for High-Performance Materials THM, Am St.-Niclas-Schacht 13, 09599 Freiberg, Germany. LZ reports small shares in a stock portfolio < 500 EUR. MDL reports funding from the NSF (USA), small amounts of royalties for several published books, and he is Advisory boards (KLI; Complexity Science Hub, Vienna, TU Graz; TISE). ESS reports funding from the National Institute of Health, FFG, FWF, H-2020, and received honoraria (about 2-3 times per year, each never >1000 Euro) for invited lectures. She is member on the Advisory board of trustees of the FWF (Austrian Science Fund), and the Scientific Advisory Board for the Annual Houska Award; honorary board member of the Austrian Cancer Help; scientific advisory board member for Cochrane Austria; advisory board member of the Austrian Scientific Community and member of Board of Trustees “Sparkling Science” Funding, Ministry of Health Austria; as well as ad hoc NIH study section member and Horizon Europe Scientific Review Panel member., (© 2022 The Author(s).)

Background: With the coronavirus disease 2019 (COVID-19) pandemic surging and new mutations evolving, trust in vaccines is essential., Methods: We explored correlates of vaccine hesitancy, considering political believes and psychosocial concepts, conducting a non-probability quota-sampled online survey with 1007 Austrians., Results: We identified several important correlates of vaccine hesitancy, ranging from demographics to complex factors such as voting behavior or trust in the government. Among those with hesitancy towards a COVID-19 vaccine, having voted for opposition parties (opp) or not voted (novote) were (95% Confidence Intervall (CI)opp, 1.44-2.95) to 2.25-times (95%CInovote, 1.53-3.30) that of having voted for governing parties. Only 46.2% trusted the Austrian government to provide safe vaccines, and 80.7% requested independent scientific evaluations regarding vaccine safety to increase willingness to vaccine., Conclusions: Contrary to expected, psychosocial dimensions were only weakly correlated with vaccine hesitancy. However, the strong correlation between distrust in the vaccine and distrust in authorities suggests a common cause of disengagement from public discourse., (© The Author(s) 2021. Published by Oxford University Press on behalf of Faculty of Public Health.)

Objectives: To explore changes in quality of life and perceived productivity, focusing on the effects of working from home during the first COVID-19 50-day mitigation period in Austria., Methods: We conducted an Austrian-representative online survey (N = 1010) of self-reported life- and work-related changes during the first COVID-19 50-day mitigation period (March 16 through May 1 2020) compared to the situation before. We used multinominal logistic regression models to identify correlates of improved/decreased quality of life in the entire sample, and of improved/decreased productivity in a subsample of the working population (N = 686). We also calculated age- and multivariable-adjusted ORs and 95% CIs of an improved/decreased quality of life and an improved/decreased productivity by work from home status., Results: During the COVID-19 mitigation period, quality of life improved in 17.5%, but decreased in 20.7% of the general Austrian population; perceived productivity at work increased in 12.7%, but decreased in 30.2% of the working population. Working from home during the mitigation period was associated with an increased quality of life (vs. none, partially: OR 2.07, 95% CI 1.09-3.91; all the time: 3.69, 1.86-7.29). In contrast, perceived productivity seemed to decrease when people worked from home (vs. none, partially: 1.42, 0.86-2.35; all the time: 1.48, 0.85-2.58). Working from home and related benefits were not equally distributed among gender, age, and educational attainment., Conclusions: A transition to more flexibility of workplace and working hours for employees could have important positive consequences for family and professional life, for stakeholders, for public health, and ultimately for the environment., (© 2021. The Author(s).)

The design of new composite materials using extreme biomimetics is of crucial importance for bioinspired materials science. Further progress in research and application of these new materials is impossible without understanding the mechanisms of formation, as well as structural features at the molecular and nano-level. It presents a challenge to obtain a holistic understanding of the mechanisms underlying the interaction of organic and inorganic phases under conditions of harsh chemical reactions for biopolymers. Yet, an understanding of these mechanisms can lead to the development of unusual-but functional-hybrid materials. In this work, a key way of designing centimeter-scale macroporous 3D composites, using renewable marine biopolymer spongin and a model industrial solution that simulates the highly toxic copper-containing waste generated in the production of printed circuit boards worldwide, is proposed. A new spongin-atacamite composite material is developed and its structure is confirmed using neutron diffraction, X-ray diffraction, high-resolution transmission electron microscopy/selected-area electron diffraction, X-ray photoelectron spectroscopy, near-edge X-ray absorption fine structure spectroscopy, and electron paramagnetic resonance spectroscopy. The formation mechanism for this material is also proposed. This study provides experimental evidence suggesting multifunctional applicability of the designed composite in the development of 3D constructed sensors, catalysts, and antibacterial filter systems., (© 2021 The Authors. Advanced Materials published by Wiley-VCH GmbH.)

We would like to extend on the article by Alley et al [...].

Investigations were carried out to obtain different lignin monomers such as vanillin and catechol as efficiently as possible, to prevent side reactions e.g., during lignin degradation. Therefore, extraction experiments were performed to determine the influence of parameters such as initial pH in the aqueous phase, organic phases containing alcohols or solvating extractants, and monomer concentrations. Cyanex 923 (Cy923) and tri-n-butyl-phosphat (TBP) diluted in kerosene were the organic phases chosen to evaluate the transport of vanillin because of their high efficiencies (>76.8%) and suitability in membrane technologies. The most efficient vanillin transport was accomplished with Cy923, as > 90% of vanillin was transferred after 5 h. However, the permeability coefficient at carrier concentration of > 0.48 mol/L was influenced not only by the diffusion but also by the organic mixture viscosity. Thus, this concentration was used in the membrane experiment containing a mixture of vanillin and catechol in the feed phase. Catechol was transported about 7% faster to the receiving phase than vanillin, presumably due to its chemical structure. Side reactions were avoided using the current liquid membrane set-up, allowing the further industrial application of an entire process, which, e.g., recovers vanillin from enzymatic lignin conversion by membrane technology.

Although the first coronavirus disease 2019 (COVID-19) wave has peaked with the second wave underway, the world is still struggling to manage potential systemic risks and unpredictability of the pandemic. A particular challenge is the "superspreading" of the virus, which starts abruptly, is difficult to predict, and can quickly escalate into medical and socio-economic emergencies that contribute to long-lasting crises challenging our current ways of life. In these uncertain times, organizations and societies worldwide are faced with the need to develop appropriate strategies and intervention portfolios that require fast understanding of the complex interdependencies in our world and rapid, flexible action to contain the spread of the virus as quickly as possible, thus preventing further disastrous consequences of the pandemic. We integrate perspectives from systems sciences, epidemiology, biology, social networks, and organizational research in the context of the superspreading phenomenon to understand the complex system of COVID-19 pandemic and develop suggestions for interventions aimed at rapid responses.

Diverse fields of modern technology and biomedicine can benefit from the application of ready-to-use chitin-based scaffolds. In this work we show for the first time the applicability of tubular and porous chitin from Caribena versicolor spiders as a scaffold for the development of an effective CuO/Cu(OH) 2 catalyst for the reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AM), and as a scaffold for the tissue engineering of selected cells. The formation of CuO/Cu(OH) 2 phases on and within the chitinous tubes leads to a hybrid material with excellent catalytic performance with respect to the reduction of p-nitrophenol. On the other hand, experimental results provide for the first time strong evidence for the biocompatibility of spider chitin with different cell types, a human progenitor cell line (hPheo1), as well as cardiomyocytes differentiated from induced pluripotent stem cells (iPSC-CMs) that were cultured on a tube-like scaffold., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Chitin, as a fundamental polysaccharide in invertebrate skeletons, continues to be actively investigated, especially with respect to new sources and the development of effective methods for its extraction. Recent attention has been focused on marine crustaceans and sponges; however, the potential of spiders (order Araneae) as an alternative source of tubular chitin has been overlooked. In this work, we focused our attention on chitin from up to 12 cm-large Theraphosidae spiders, popularly known as tarantulas or bird-eating spiders. These organisms "lose" large quantities of cuticles during their molting cycle. Here, we present for the first time a highly effective method for the isolation of chitin from Caribena versicolor spider molt cuticle, as well as its identification and characterization using modern analytical methods. We suggest that the tube-like molt cuticle of this spider can serve as a naturally prefabricated and renewable source of tubular chitin with high potential for application in technology and biomedicine., Competing Interests: The authors declare no conflict of interest.

Fabrication of biomimetic materials and scaffolds is usually a micro- or even nanoscale process; however, most testing and all manufacturing require larger-scale synthesis of nanoscale features. Here, we propose the utilization of naturally prefabricated three-dimensional (3D) spongin scaffolds that preserve molecular detail across centimeter-scale samples. The fine-scale structure of this collagenous resource is stable at temperatures of up to 1200°C and can produce up to 4 × 10-cm-large 3D microfibrous and nanoporous turbostratic graphite. Our findings highlight the fact that this turbostratic graphite is exceptional at preserving the nanostructural features typical for triple-helix collagen. The resulting carbon sponge resembles the shape and unique microarchitecture of the original spongin scaffold. Copper electroplating of the obtained composite leads to a hybrid material with excellent catalytic performance with respect to the reduction of p -nitrophenol in both freshwater and marine environments., (Copyright © 2019 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works. Distributed under a Creative Commons Attribution NonCommercial License 4.0 (CC BY-NC).)

This Review provides an overview of valuable metals, the supply of which has been classified as critical for Europe. Starting with a description of the current state of the art, novel approaches for their recovery from primary resources are presented as well as recycling processes. The focus lies on developments since 2005. Chemistry strategies which are used in metal recovery are summarized on the basis of the individual types of deposit and mineral. In addition, the economic importance as well as utilization of the metals is outlined., (© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Wheat straw was subjected to three different processes prior to saccharification, namely alkaline pulping, natural pulping and autohydrolysis, in order to study their effect on the rate of enzymatic hydrolysis. Parameters like medium concentration, temperature and time have been varied in order to optimize each method. Milling the raw material to a length of 4mm beforehand showed the best cost-value-ratio compared to other grinding methods studied. Before saccharification the pulp can be stored in dried form, leading to a high yield of glucose. Furthermore the relation of pulp properties (i.e. intrinsic viscosity, Klason-lignin and hemicelluloses content, crystallinity, morphology) to cellulose hydrolysis is discussed., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

The substitution potential of sewage sludge for German primary phosphate imports has been estimated as 40%. Yet, a marketable option for the full scale recovery has been lacking. This study focuses on a full-scale process for the manufacture of a P-fertilizer from sewage sludge ash (SSA) adapted from the production of Triple Superphosphate. Given (i) conformity of the input with phosphate ores mined from sedimentary deposits, (ii) comparability of the product with a commercially available P-fertilizer regarding contaminant levels, P-fractionation and yield effects, and (iii) compliance of the output with the German Fertilizer Ordinance the RecoPhos P 38 fertilizer was discharged from the waste legislation regime. The fertilizer is currently being produced at a rate of 1000 tonnes per month and sold at a competitive price., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

In the field of industrial biocatalysis, formate dehydrogenase (FDH) is well established, in particular for its broad application in cofactor regeneration. Further applications have been limited by the enzyme's narrow range of substrates. These restrictions have been overcome now by the finding, that the enzyme is capable of selectively cleaving formic acid esters to the respective alcohol. Five homologous alkyl formates and phenyl formate as an aromatic ester were converted quantitatively by FDH from Candida boidinii in a batch reaction within 3 to 5 h. The substrates were turned irreversibly into carbon dioxide and the respective alcohol through hydride abstraction from the formyl group with full conversion. The mechanism shows parallels to hydrolysis reactions of the A(AC)1-type. K(M)-values and reactions rates of the tested formic acid esters display a tendency to higher conversion rates with increasing chain length. FDH emerged to be a superior deformylation catalyst compared to hydrolases as well as classical catalysts, as was shown by the selective deformylation of 1-acetoxy-4-formoxy butane (92%) and 1,3-bis(3-formoxypropyl)tetramethyldisiloxane. In particular its capability to distinguish between formic acid esters and non-formic acid esters renders the method particularly suitable for protective group chemistry. Furthermore the completeness of deformylation allows for converting substrates highly incompatible with aqueous media like siloxanes within a few hours.

Importance of the Field: Predicting drug metabolism after oral administration is highly complex, yet indispensable. Hitherto, drug metabolism mainly focuses on hepatic processes. In the intestine, drug molecules encounter the metabolic activity of microorganisms prior to absorption through the gut wall. Drug biotransformation through the gastrointestinal microflora has the potential to evoke serious problems because the metabolites formed may cause unexpected and undesired side effects in patients. Hence, in the course of drug development, the question has to be addressed if microbially formed metabolites are physiologically active, pharmaceutically active or even toxic. In order to provide answers to these questions and to keep the number of laboratory tests needed low, predictive tools - in vivo as well as in silico - are invaluable., Areas Covered in This Review: This review gives an outline of the current state of the art in the field of predicting the drug biotransformation through the gastrointestinal microflora on several levels of modelling., What the Reader Will Gain: A comprehensive review of the literature with a thorough discussion on assets and drawbacks of the different modelling approaches., Take Home Message: The impact of the gastrointestinal drug biotransformation on patients' health will grow with increasing complexity of drug entities. Predicting metabolic fates of drugs by combining in vitro and in silico models provides invaluable information which will be suitable to particularly reduce in vivo studies.

The synthesis of pharmaceuticals and catalysts more and more relies on enantiopure chiral building blocks. These can be produced in an environmentally benign and efficient way via bioreduction of prochiral ketones catalyzed by dehydrogenases. A productive source of these biocatalysts is the yeast Saccharomyces cerevisiae, whose genome also encodes a reductase catalyzing the sequential reduction of the gamma-diketone 2,5-hexanedione furnishing the diol (2S,5S)-hexanediol and the gamma-hydroxyketone (5S)-hydroxy-2-hexanone in high enantio- as well as diastereoselectivity (ee and de >99.5%). This enzyme prefers NADPH as the hydrogen donating cofactor. As NADH is more stable and cheaper than NADPH it would be more effective if NADH could be used in cell-free bioreduction systems. To achieve this, the cofactor binding site of the dehydrogenase was altered by site-directed mutagenesis. The results show that the rational approach based on a homology model of the enzyme allowed us to generate a mutant enzyme having a relaxed cofactor preference and thus is able to use both NADPH and NADH. Results obtained from other mutants are discussed and point towards the limits of rationally designed mutants.

The enantiopure (2S,5S)-hexanediol serves as a versatile building block for the production of various fine chemicals and pharmaceuticals. For industrial and commercial scale, the diol is currently obtained through bakers' yeast-mediated reduction of 2,5-hexanedione. However, this process suffers from its insufficient space-time yield of about 4 g L(-1) d(-1) (2S,5S)-hexanediol. Thus, a new synthesis route is required that allows for higher volumetric productivity. For this reason, the enzyme which is responsible for 2,5-hexanedione reduction in bakers' yeast was identified after purification to homogeneity and subsequent MALDI-TOF mass spectroscopy analysis. As a result, the dehydrogenase Gre2p was shown to be responsible for the majority of the diketone reduction, by comparison to a Gre2p deletion strain lacking activity towards 2,5-hexanedione. Bioreduction using the recombinant enzyme afforded the (2S,5S)-hexanediol with >99% conversion yield and in >99.9% de and ee. Moreover, the diol was obtained with an unsurpassed high volumetric productivity of 70 g L(-1) d(-1) (2S,5S)-hexanediol. Michaelis-Menten kinetic studies have shown that Gre2p is capable of catalysing both the reduction of 2,5-hexanedione as well as the oxidation of (2S,5S)-hexanediol, but the catalytic efficiency of the reduction is three times higher. Furthermore, the enzyme's ability to reduce other keto-compounds, including further diketones, was studied, revealing that the application can be extended to alpha-diketones and aldehydes.

A rapid HS-SPME-GC-MS (headspace solid-phase microextraction-gas chromatography-mass spectrometry) method has been developed for determination of menthone, isomenthone, neomenthol and menthol in serum samples with and without enzymatic cleavage. These flavour compounds are characteristic markers for consumption of peppermint liqueurs as well as certain digestif bitters, herbal and bitter liqueurs. This method enabled the detection of the four compounds with a limit of detection (LOD) of 2.1 ng mL(-1) (menthone and isomenthone), 2.8 ng mL(-1) (neomenthol) and 4.6 ng mL(-1) (menthol), and a limit of quantification (LOQ) of 3.1 ng mL(-1) (menthone and isomenthone), 4.2 ng mL(-1) (neomenthol) and 6.8 ng mL(-1) (menthol) in serum samples. The method shows good precision intraday (3.2-3.8%) and interday (5.8-6.9%) and a calibration curve determination coefficient (R(2)) of 0.990-0.996. Experiments were conducted with a volunteer, who consumed peppermint liqueur on three different days under controlled conditions. At defined intervals, blood samples were taken, and the concentration-time profiles for serum menthone, isomenthone, neomenthol and menthol, as free substances as well as glucuronides, were determined. Both menthol and neomenthol underwent a rapid phase II metabolism, but minor amounts of free substances were also detected. Menthone and isomenthone were rapidly metabolised and were found in lower concentrations and over a shorter time span than the other analytes. In blood samples taken from 100 drivers who claimed to have consumed peppermint liqueur prior to the blood sampling, menthone, isomenthone, neomenthol and menthol were detected in the serum as free substances in concentrations between 3.1 and 7.0 ng mL(-1) in eight cases (menthone), 3.1 and 11.3 ng mL(-1) in eight cases (isomenthone), 5.3 and 57.8 ng mL(-1) in nine cases (neomenthol) and 8.0 and 92.1 ng mL(-1) in nine cases (menthol). The sum values of free and conjugated substances ranged between 4.2 and 127.8 ng mL(-1) in 35 cases for neomenthol and 11.0 and 638.2 ng mL(-1) in 59 cases for menthol. Menthone and isomenthone were not conjugated. These test results confirmed that the analysis of characteristic beverage aroma compounds, such as menthone, isomenthone, neomenthol and menthol, can be used for specific verification of post-offence alcohol consumption claims.

Biocatalytical approaches have been investigated in order to improve accessibility of the bifunctional chiral building block (5S)-hydroxy-2-hexanone ((S)-2). As a result, a new synthetic route starting from 2,5-hexanedione (1) was developed for (S)-2, which is produced with high enantioselectivity (ee >99%). Since (S)-2 can be reduced further to furnish (2S,5S)-hexanediol ((2S,5S)-3), chemoselectivity is a major issue. Among the tested biocatalysts the whole-cell system S. cerevisiae L13 surpasses the bacterial dehydrogenase ADH-T in terms of chemoselectivity. The use of whole-cells of S. cerevisiae L13 affords (S)-2 from prochiral 1 with 85% yield, which is 21% more than the value obtained with ADH-T. This is due to the different reaction rates of monoreduction (1-->2) and consecutive reduction (2-->3) of the respective biocatalysts. In order to optimise the performance of the whole-cell-bioreduction 1 2 with S. cerevisiae, the system was studied in detail, revealing interactions between cell-physiology and xenobiotic substrate and by-products, respectively. This study compares the whole-cell biocatalytic route with the enzymatic route to enantiopure (S)-2 and investigates factors determining performance and outcome of the bioreductions.

Caffeine affects the stereoselectivity of microbial high cell density reductions with commercial grade Saccharomyces cerevisiae (Baker's yeast). Cyclic beta-keto esters ethyl 2-oxocyclopentanoate (1) and ethyl 2-oxocyclohexanoate (3) were shown to be reduced with increased diastereoselectivity (1: 90.1 --> 92.1% de, 3: 75.0 --> 90.0% de) after addition of caffeine. Effects on enantioselectivity were less pronounced (1: 97.3 --> 98.5% ee, 3: 90.1 --> 92.1% ee). The observations are ascribed to the action of caffeine on cellular calcium homeostasis. These effects are accompanied by caffeine-induced cell-death, which preferably takes effect on pre-stressed cells which were found to decrease diastereoselectivity.

Extractive work-up of whole-cell biotransformations generally suffers from the formation of stable gels and slimes upon addition of the organic solvent to the cell suspension and the cell-free solution, respectively. This problem has been overcome by enzymatic lysis of emulsifying agents present in the medium through addition of hydrolases. Of these agents, proteases have exhibited the most powerful de-emulsifying activity. Enzyme treatment of cell-free culture media of Saccharomyces cerevisiae with pronase E drastically reduced phase separation time (t(p)) from 1 week to 30 min without significantly affecting product integrity. Yeast cell suspensions were de-emulsified best with protease N-01, where phase separation was complete after 1 h. As was exemplified with cell-free culture media of Lactobacillus kefir, wherein addition of pronase E or protease N-01 reduced t(p) from 1 week to 2 h each, this practical, ready-to-use method is appropriate for both fungal and bacterial biocatalysts.

The bioavailability of lipophilic substrates is critical for biotransformations with isolated enzymes as well as with whole cells. With the example of a series of lipophilic ketones the suitability of saccharides as potent solubilisers for highly lipophilic substrates was demonstrated. Best results were obtained for d-glucose, which increased substrate solubility up to 50 times. In whole-cell biocatalysis the sugar acts both as solubiliser and as carbon source for which reason this procedure does not impair cell physiology and is unique in being environmentally benign. The capability of saccharides to solubilise lipophilic compounds in aqueous media sources from their ability to form hydrophilic and lipophilic domains at hydrophobic interfaces, thus forming cyclodextrin-like structures around the lipophilic substrate.

Determination of inorganic chloride released from a chloro-organic compound by whole-cell or enzymatic dehalogenation can be affected by free thiols, phosphate, sugars, pH, the chloro-organic substrate, and its dehalogenation product. For these reasons a highly sensitive, colorimetric chloride assay on the basis of [FeCl]2+ (lambda(max) = 340 nm) formed in highly acidic medium which is insensitive to composition of culture medium, free thiols, substrate, and dehalogenation product was developed. It is applicable to both fungal and bacterial high-cell-density cultures. The [FeCl]2+ method provides reliable data and is convenient for the rapid and facile determination of dehalogenation kinetics.

Saccharomyces cerevisiae reduces the beta-keto ester ethyl 2-chloroacetoacetate to the respective chiral cis- and trans-beta-hydroxy esters. In the course of chiral reduction, competing dehalogenation of the xenobiotic substrate to ethyl acetoacetate occurs, in a reaction mediated by cytosolic glutathione (GSH). Mechanistically, the dechlorination is a novel type of glutathione-dependent dehalogenation catalysed by an as yet unidentified glutathione-dependent dehalogenase. The first step consists of a nucleophilic replacement of the chloride substituent by glutathione. In the subsequent enzyme-catalysed step, a second glutathione molecule liberates the dehalogenation product by thiolytic attack at the thioether bridge, resulting in a net transfer of two electrons to the substrate and in the formation of glutathione disulfide (GSSG). Being effective under aerobic conditions and catalysed by a fungus, this reductive dechlorination of an aliphatic substrate is an outstanding example of a novel, glutathione-mediated microbial dehalogenation.

For the seco-dodecahedradiene 1, in which the distance d ππ between the carbon atoms of the two double bonds ranges from 2.90 to 3.20 Å and pyramidalization angles Φ range from 14.9 to 35.5°, the geometrical prerequisites for in-plane (σ)-homoconjugative (σ-bishomoaromatic) electron delocalization in 4C/3(2)e cations could be better defined. Whilst the 4C/3e radical cation is persistent in a matrix, the 4C/2e dication in superacid medium is, at best, an intermediate en route to the stable bisallylic dication., (© 2001 WILEY-VCH Verlag GmbH, Weinheim, Fed. Rep. of Germany.)

Two variants of the "S N 2 route" from pagodanes (A, B) to functionalized dodecahedranes (D, F) and particularly dodecahedradienes (E) offer considerable improvements in the number of operations (from nine to five to three) and yields (e.g., for diester F from 55-65 to 70-75 to 85-91%). Key steps are the regio- and stereospecific introduction of four to six bromine substituents into dimethyl pagodane-4-syn,9-syn-dicarboxylate (1 b) and a highly complex (thirteen bond-breaking/bond-forming events in four participating structures). yet very convenient (one-pot operation) and extremely efficient (nearly quantitative) transformation of secopagodane to bissecododecahedradiene with complete stereocontrol in transannular CH 2 functionalizations. The prohibitively low kinetic acidity of "caged" hydrogens has so far only been overcome with the recently reported P 2 F reagent (Schwesinger). Further improvement of the overall economy of the pagodane → dodecahedrane scheme has been achieved by efficiently channeling a byproduct of the pagodane synthesis (ca. 10%) back into the S N 2 track., (Copyright © 1996 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)