Recent developments in oxidative biocatalytic cascades

Biocatalytic cascades that involve enzymatic oxidation as one or more key steps are powerful tools to access valuable chemicals with various functionalizations starting from simple substrates, without the isolation of intermediates. This review discusses the recent advances in oxidative cascades, with perspectives given on the current limitations and future developments. The strategies employed to achieve efficient supply of redox cofactors are also highlighted. The examples include cascades that begin with alkene epoxidation, alkane hydroxylation, alcohol oxidation or amine oxidation. These oxidative steps are followed by a variety of enzyme-catalyzed functionalizations, producing a diverse range of high-value products.     

Food oral processing: Recent developments and challenges

As the very first step of food consumption, food oral processing is not only of great importance to food intake and the following digestion and adsorption, but also provides the necessary sensory attributes that please the consumer. Starting from the first bite, to oral manipulation including mastication and transportation, until bolus formation and swallowing, food products undergo a variety of physical and biochemical changes over a wide range of time and length scales. A number of efforts had been made to uncover the mechanisms in each oral processing step; some of which are still poorly understood. This review covers some of the most recent progress made in the area of food oral processing, with an emphasis on eating and swallowing difficulties in the elderly and the corresponding model food development. It also includes the oral surface coating and lubrication and the dynamic textural perception during food oral processing. The authors hope that this will facilitate food scientists, psychologists, dentists and other clinical researchers to further understand and reveal the detailed controlling mechanisms and governing principles of food oral processing.     

Recent developments of chemical processes and catalysts in Japan

Recent developments of (petro)chemical processes and of the catalysts needed for them are reviewed. In this paper (part I of a two-part series), oxidation, oxidative dehydrogenation, ammoxidation, hydrogenation, hydroformylation and carbonylation are described. Part II will treat acid and base catalysis, enzyme and microbial catalysis, and stereospecific polymerization references.     

Recent developments on ion-exchange membranes and electro-membrane processes

Rapid growth of chemical and biotechnology in diversified areas fuels the demand for the need of reliable green technologies for the down stream processes, which include separation, purification and isolation of the molecules. Ion-exchange membrane technologies are non-hazardous in nature and being widely used not only for separation and purification but their application also extended towards energy conversion devices, storage batteries and sensors etc. Now there is a quite demand for the ion-exchange membrane with better selectivities, less electrical resistance, high chemical, mechanical and thermal stability as well as good durability. A lot of work has been done for the development of these types of ion-exchange membranes during the past twenty-five years. Herein we have reviewed the preparation of various types of ion-exchange membranes, their characterization and applications for different electro-membrane processes. Primary attention has been given to the chemical route used for the membrane preparation. Several general reactions used for the preparation of ion-exchange membranes were described. Methodologies used for the characterization of these membranes and their applications were also reviewed for the benefit of readers, so that they can get all information about the ion-exchange membranes at one platform. Although there are large number of reports available regarding preparations and applications of ion-exchange membranes more emphasis were predicted for the usefulness of these membranes or processes for solving certain type of industrial or social problems. More efforts are needed to bring many products or processes to pilot scale and extent their applications.     

Low-temperature direct ammonia fuel cells: Recent developments and remaining challenges

Low-temperature direct ammonia fuel cells (DAFCs) are fueled directly by ammonia, a carbon-neutral fuel stored in the liquid state under low pressure. Liquid ammonia has advantages over compressed hydrogen gas, including higher energy density and facilitated distribution and refill. The beginning-of-life performance reported until recently for low-temperature DAFCs has been substantially lower than that of polymer electrolyte fuel cells fueled by hydrogen. We discuss here promising recent advances in electrocatalyst development, cell performance, and cell performance stability for low-temperature DAFCs, including beginning-of-life peak power density of 420 mW/cm², and operation over several days at constant current. In addition, we describe technology gaps that must be closed for low-temperature DAFCs to achieve the performance required for practical applications.     

Recent developments in neutron-induced gamma activation for on-line multielemental analysis in industry

Neutron-induced gamma activation is an important method for on-line multi-elemental analysis. It has a long history of use in industrial applications, in particular the minerals and energy sectors, although it has also been applied in other areas, including medicine and security. This paper reviews significant developments and trends of the last decade in technology, in particular in the areas of sources, detectors and analytical methods. Changes in implementation such as the increasing use of neutron inelastic scattering reactions and the development of on-belt designs are also discussed. This revised version was published online in July 2006 with corrections to the Cover Date.     

Recent developments in chiral capillary electrophoresis and applications of this technique to pharmaceutical and biomedical analysis

This paper provides an overview of the current status of chiral capillary electrophoresis (CE). The emphasis is placed on the application of CE in chiral separation of various racemic compounds. During the last two years about 280 papers, several review articles, and two entire issues, edited by S. Fanali (Electrophoresis 1999, 20, 2577-2798, and H. Nishi and S. Terabe (J. Chromatogr. A 2000, 879, 1-471.) have been devoted to chiral CE. Enantiomeric separations of various compounds, e.g., pharmaceuticals, drug candidates, drugs and related metabolites in biological fluids, amino acids, di- and tri peptides, pesticides and fungicides, have been performed using different chiral selectors. Native and derivatized cyclodextrins continue to be the most widely used chiral selectors. Other chiral selectors such as natural and synthetic chiral micelles, crown ethers, chiral ligands, proteins, oligo- and polysaccharides, and macrocyclic antibiotics have also been applied to chiral CE separations.     

Transition metal catalyzed hydroarylation of olefins using unactivated substrates: Recent developments and challenges

The addition of aromatic C-H bonds across olefin CC bonds (olefin hydroarylation) is an important synthetic methodology for the preparation of alkylated arenes. Traditional methods utilizing Friedel-Crafts catalysts result in a significant waste stream and substantial polyalkyated products. In order to achieve high overall yield of monoalkylated compounds, Friedel-Crafts catalysis must be combined with a second transalkylation catalytic step. Reactions that incorporate substituted olefins are selective for branched products. In addition, the regioselective synthesis of disubstituted alkyl arenes is difficult to achieve. Recent development of transition metal based catalysts provides non-Friedel-Crafts pathways for the production of alkyl arenes. Systems based on Ru(II), Ir(III), and Pt(II) have been developed, and mechanistic studies have begun to provide insight into the details of these catalysts. Herein, we review recently published results in the area of transition metal catalyzed olefin hydroarylation with a comparison of known catalysts and discussion of challenges yet to be overcome.     

Monitoring anthropogenic particles in the environment: Recent developments and remaining challenges at the forefront of analytical methods

Anthropogenic particles at the microscale and nanoscale are posing risks to human health and the ecosystem. Engineered nanomaterials, microplastics and nanoplastics, soot, road and tire wear are a few prominent examples of particles that are either intentionally manufactured or incidentally produced and released into the environment. Analytical developments in the past few decades have made it possible to study particles in the microscale and nanoscale; however, there is still no universal protocol of analysis and caveats exist in the use of the most prominent techniques. The task is challenging because of the large variety of particle properties and the complexity of environmental media. This review discusses a selected group of techniques most likely to play a key role in future monitoring activities and their recent developments and inherent shortcomings.     

Measuring the performance of quality assurance processes: pharmaceutical industry deviation management case study

This article presents experience from the practice of a successful pharmaceutical company related to design and implementation of performance measures (PMs) for deviation management linked to the analysis of impact on the production cost for the selected product. Case study focuses on PMs within good manufacturing practice (GMP) processes related to quality assurance (QA) and quality management, with the aim of complying with its future requirements proposed by the European Commission. Critical areas were identified based on data gathered from the industrial deviation database. Implementation of the suggested corrective actions showed significant improvement in terms of reducing their number for more than 50% per selected deviation category. The results obtained in the course of this practice-oriented study contribute to further improvement of deviation management in the pharmaceutical industry and performance measurement of other GMP processes. The suggested performance measurement concept and problem-solving techniques may serve both practitioners and the decision-makers within QA and quality control (QC) in order to improve their processes by implementing relevant regulatory requirements for quality management and maintain compliance.     

Shape and color of au nanoparticles follow biocatalytic processes

The NAD(P)H-mediated growth of Au nanoparticles (NPs) in the presence of ascorbic acid, AuCl4-, and cetyltrimethylammonium bromide leads to the formation of shaped NP structures consisting of dipods, tripods, and tetrapods. The shaped particles exhibit a red-shifted plasmon absorbance at lambda = 680 nm, consistent with the existence of a longitudinal plasmon exciton. High-resolution transmission electron microscopy analysis of the tripod and tetrapod structures reveals directional growth along the <211> and <010> directions, respectively. The shaped Au NPs could be generated by a biocatalytic process using alcohol dehydrogenase, NAD+, and ethanol, and the resulting blue color provides a colorimetric test for ethanol.     

Recent developments in radioimmunoassay

Recent developments in the radioimmunoassay of steroid and peptide hormones are discussed. The modern requirement for the rigorous demonstration and maintainance of accuracy is emphasized. The future of immunoassay in clinical chemistry is discussed with special reference to quality control and automation.     

Recent developments in isotachophoresis

This paper is summarizing the contributions to the analytical capillary isotachophoresis published during the period 1981-1984. It characterizes the present state of the method and covers theory, fundamental analytical aspects, instrumentation and applications. Special attention was payed to the fundamental analytical aspects, and a detailed discussion is given of the selection of electrolyte systems, stability of zones and separability of substances. The present commercial instrumentation is also briefly described.     

Designing for sustainability with biocatalytic and chemoenzymatic cascade processes

Cascade reactions have been widely recognized to cut costs, decrease solvent usage, and reduce cycle times in chemical processes. Recently, biocatalytic cascades have altered how we design synthetic routes to complex molecules to achieve sustainable commercial processes for pharmaceutical, agricultural, and fine chemical industries. With advancements in protein engineering and an increase in the number of enzyme classes available to chemists, industrial and academic groups alike have endeavored to expand the scope of biocatalysis from single reactions to multi-enzyme cascades to rapidly build complex molecular structures. Recent reports have drawn inspiration from biosynthetic pathways and have applied engineered enzymes to in vitro enzymatic cascades. Furthermore, combining transition-metal catalysis and enzymes in one-pot chemoenzymatic cascades likewise serves to broaden the scope of biocatalysis, enabling traditional chemical reactions to be performed under mild aqueous conditions. In this article, we review recent biocatalytic and chemoenzymatic cascades from 2019 to 2021.     

Cyclodextrin polymers in the pharmaceutical industry

The potential applications of cyclodextrin polymers (soluble and insoluble ones) in the pharmaceutical industry are reviewed. The soluble polymers are good solubilizers of drugs thus enhancing their bioavailability. When applied topically the insoluble bead polymer accelerates the healing of burns and ulcers. It can also be used for chromatography and to remove certain components from mixtures. The insoluble ground polymer is an effective tablet disintegrant in direct compression systems as well as in formulations made by wet granulation.Lecture, presented at the meeting Anwendungsmöglichkeiten von Cyclodextrin in der pharmazeutischen Industries, Berlin, 21/22 September 1987.