Potential of fish by‐products as a source of novel marine lipases and their uses in industrial applications

An abundance of fish by‐products worldwide provides a diverse and highly valuable raw material for the extraction of numerous biochemicals, including lipases. Marine lipases are versatile enzymes possessing high activity at relatively low temperatures and unique fatty acid specificity. The challenges associated with marine lipases revolve around their cost of extraction and chemical instability. As these are overcome there is scope for commercial exploitation. The potential applications of marine lipases include flavour development in food products and synthesis of specialty lipids such as omega‐3 concentrates.     

Microfluidic reactor with immobilized enzyme-from construction to applications: A review

Microfluidic, as the systems for using microchannel (micron-or sub-micron scale) to process or manipulate microflow, is being widely applied in enzyme biotechnology and biocatalysis. Microfluidic immobilized enzyme reactor (MIER) is a tool with great value for the study of catalytic property and optimal reaction parameter in a flourishing and highly producing manner. In view of its advantages in efficiency, economy, and addressable recognition especially, MIER occupies an important position in the investigation of life science, including molecular biology, bioanalysis and biosensing, biocatalysis etc. Immobilization of enzymes can generally improve their stability, and upon most occasions, the immobilized enzyme is endowed with recyclability. In this review, the enzyme immobilization techniques applied in MIER will be discussed, followed by summarizing the novel developments in the field of MIER for biocatalysis, bioconversion and bioanalysis. The preponderances and deficiencies of the current state-of-the-art preparation ways of MIER are peculiarly discussed. In addition, the prospects of its future study are outlined.     

Hydrogel networks as nanoreactors: A novel approach to silver nanoparticles for antibacterial applications

Hydrogel networks based on N-isopropylacrylamide (NIPAM) and sodium acrylate (SA) were prepared by redox-polymerization in the presence of N,N′-methylenebisacrylamide (MBA). Highly stable and uniformly distributed silver nanoparticles have been prepared using these hydrogel networks as a carrier via in situ reduction of silver nitrate in the presence of sodium borohydride as a reducing agent. It has been demonstrated that the hydrogel hybrid with different sizes of silver nanoparticles can be effectively employed as antibacterial material.     

Organosilicon-functionalized polyolefins,a kind of designable and versatile polymer: From preparation to applications

Functionalization of polyolefins has been a challenging but promising issue since their invention, with the promise of retaining inherent properties and overcoming the low reactivity and poor compatibility. Organosilicons are widely used for polymer modification to improve thermal stability, hydrophobicity, compatibility, and permeability. Since the advent of alkoxysilane-grafted polyethylene in 1960s, organosilicon-functionalized polyolefins (Si-PO) have been extensively prepared, investigated, and developed. The structure of Si-PO is designable due to the flexible chemistry of organosilicons; crosslinked, long chain branched, and star-shaped polyolefins are available after the introduction of alkoxysilanes, chlorosilanes, hyrdosilanes, or alkylsilanes into polyolefins, and generally these polymers are more compatible to fillers than commercial polyolefins due to stronger interaction. In addition, functionalization of polyolefins with stable organosilicon components such as polysiloxane and polysilsesquioxane can improve thermostability, hydrophobicity, gas permeability, and aging resistance; such polyolefins are usually grafted or block polymers. In this review, Si-PO is classified according to the functional organosilicon component, namely alkoxysilane, chlorosilane, hydrosilane, alkylsilane, polysiloxane, and polysilsesquioxane; their preparations are discussed minutely and summarized with manifold examples. Silicon-containing structures impart the unique properties of organosilicons to polyolefins; applications of Si-PO as compatibilizers, processing aids, battery separators, and separating membranes have been widely reported and are discussed here.     

Asymmetric catalytic hydrogenation. Design of new Ru catalysts and chiral ligands: from laboratory to industrial applications

This Account covers the design of Ru catalysts and ligands. Two classes of chiral phosphine ligands are prepared: the electron-rich trans-2,4-substituted phosphetanes, readily available from optically pure 1,3-diol cyclic sulfates, and atropoisomeric ligands (SYNPHOS, MeO-NAPhePHOS, bearing heterotopic biaryl moieties, and a chiral water-soluble diguanidinium binaphthyl diphosphine, Digm-BINAP). Applications of these ligands to rhodium- and ruthenium-mediated hydrogenation of ketones and olefins have been reported with high enantioselectivities. The recognition abilities of Ru-SYNPHOS for a wide range of ketones is superior to those observed with BINAP, MeO-NAPhePHOS, and MeO-BIPHEP. Several biologically active compounds have been prepared through dynamic kinetic resolution. This work gives access to a number of highly active catalysts of the type [Ru(biphosphane)(H)(eta(6)-cot)]BF(4). These catalysts have demonstrated their utility in the enantioselective hydrogenation of the tetrasubstituted cyclopentenone "dehydrodione", which leads to the commercially important perfume component Paradisone (Firmenich).     

Synergism of enzymes in chemical pulp bleaching from an industrial point of view: A critical review

Enzymes are biological catalysts and are very specific, catalyzing either a single chemical reaction or a limited number of closely related reactions. For example, xylanases are enzymes that catalyze the cleavage of polymeric xylan and thereby break down this hemicellulose. The first xylanase enzyme preparations used in the bleaching process of chemical pulp also contained cellulase, which catalyzes the hydrolysis of cellulose. This obviously had an adverse effect on pulp yield and quality. Unfortunately, this setback gave enzyme-assisted pulp bleaching a negative reputation. At a later stage, enzyme producers managed to engineer enzyme production strains that generated cellulase-free xylanase preparations. However, due to the initial negative experiences with the earlier enzyme mixtures, only a limited number of companies in the pulp industry have seriously considered using these so-called second-generation enzymes in their bleach plants. It is apparent that these improved enzyme preparations would bring about significant benefits in terms of chemical cost savings and effluent quality. In addition to xylanase-aided bleaching, it is possible to improve the effectivity further by adding other enzymes, such as lipase and esterase, to create an enzyme cocktail. This may be particularly beneficial in the bleaching of hardwood pulp, such as white birch, which often encounters complex and troublesome problems with wood extractives. By adding different types of enzymes at more than one position in the fiberline, even further improvements are possible. The main objective of this review is to discuss the advantages of incorporating modern enzyme preparations in the bleaching of chemical pulp.     

Functional biohybrid materials synthesized via surface-initiated MADIX/RAFT polymerization from renewable natural wood fiber: Grafting of polymer as non leaching preservative

Crude wood fibers represent a wide class of renewable resources. The surface modification of such materials via covalent grafting of polymer offers new surface properties with non-leaching coating. The grafting of the polymer chains was achieved by surface-initiated controlled radical polymerization through a grafted xanthate chain transfer agent. Macromolecular design via interchange of xanthate (MADIX) technique was chosen to graft poly(vinyl acetate), polystyrene, poly(n-butyl acrylate) and poly(4-vinylbenzyl chloride)-polystyrene amphiphilic cationic copolymers. Water contact angle measurements highlighted the hydrophobization of the wood fiber surface with a nanoscaled polymer monolayer indicating the appropriate coverage of the fiber. X-ray photoelectron spectroscopy showed the successful grafting of the polymer after drastic washing procedure. The quaternization of the grafted polystyrene-co-poly(4-vinyl benzyl chloride) copolymers with tertiary amine allows the introduction of biocide quaternary ammonium functions while preserving the hydrophobic character of the modified wood fiber when introducing a long alkyl chain in the statistical copolymer. Finally, the cationic copolymer was subjected to Coniophora Puteana to evaluate its propensity to limit the fungi expansion.     

Structural DNA nanotechnology: from design to applications

The exploitation of DNA for the production of nanoscale architectures presents a young yet paradigm breaking approach, which addresses many of the barriers to the self-assembly of small molecules into highly-ordered nanostructures via construct addressability. There are two major methods to construct DNA nanostructures, and in the current review we will discuss the principles and some examples of applications of both the tile-based and DNA origami methods. The tile-based approach is an older method that provides a good tool to construct small and simple structures, usually with multiply repeated domains. In contrast, the origami method, at this time, would appear to be more appropriate for the construction of bigger, more sophisticated and exactly defined structures.     

Pd loaded bismuth ferrite: A versatile perovskite for dual applications as acetone gas sensor and photocatalytic dye degradation of malachite green

Herein we report the palladium loaded bismuth ferrite for its bidirectional application as acetone gas sensor and photocatalytic dye degradation of malachite green. The motivation for loading Pd on bismuth ferrite (BFO) is due to its fascinating catalytic redox reactions causing faster adsorption and desorption of the oxygen molecules over the metal oxide. The planned perovskites were developed via surfactant assisted sol-gel auto-combustion route, and characterized their physico-chemical properties using XRD, SEM, TEM, HRTEM, EDAX, XPS and BET. The developed BFO showed the best selectivity towards acetone, whose response was 69% at 300 °C operating temperature for 500 ppm gas concentration. By tuning the surface area and catalytic behavior using CTAB and Pd loading, respectively, the enhancement in the gas response properties of BFO was achieved to 95% with the response and recovery time of 75 s and 104 s. The 1 wt% Pd loaded BFO showed the highest response (95%) in comparison to rest of the Pd loadings (0.5, 1.5 and 2.0 wt%). Moreover, the sunlight driven photocatalytic dye degradation of malachite green is carried out at 1 h exposure time. Here as well, 1 wt% Pd loaded BFO exhibited the maximum dye degradation efficiency of 51%. The results of this study demonstrate the developed perovskites have a significant potential for the use in dual applications such as acetone gas sensor and MG photocatalysis.     

如何使我国氮肥企业尽快摆脱困境

氮肥在我国化肥工业中占主导地位,面对愈来愈激烈的市场竞争,众多氮肥生产企业举步维艰,如何使这些工厂尽快摆脱困境,继续发展壮大,根据不同规模企业的特点,提出了相应的建议。     

Acrylic polymers derived from high solid emulsions as excipients to pharmaceutical applications: synthesis and characterization

Novel polymeric excipients need to be designed to allow for the controlled delivery of many drugs to treat a variety of diseases. In this work, two polymers based on different proportions of ethyl acrylate, methyl methacrylate, and butyl methacrylate were synthesized by multistage emulsion polymerization using a redox initiator system to yield excipients for the manufacture of prolonged release tablets by the coating or compression technique. Fourier Transform Infrared spectrometer (FTIR) indicated that the polymerization reaction of the monomers was complete without carbon double bond absorption bands. Differential Scanning Calorimetry (DSC) analysis indicated that the glass transition temperature (T _g) of the polymers was around 50 °C. The dispersions obtained were characterized in terms of particle size and particle size distribution (PSD) using Dynamic Light Scattering (DLS), and the particle charge (zeta potential) was measured by electrophoretic mobility. The measurements showed particle diameters of approximately 200 nm and a zeta potential close to −60 mV. The low viscosity obtained for the polymers was attributed to bimodal PSD. The dispersions were freeze dried and the particles were submitted to in vitro cell tests to make a preliminary check of the toxicity of the materials. The low viscosity of the polymers, the absence of volatile solvents, and the high solid content (>50%) are ideal for these polymers to be used as coatings and matrices pharmaceutical excipients for prolonged release tablets. In vitro MTT tests suggested that the materials can be considered nontoxic.     

Catalytic combustion: from reaction mechanism to commercial applications

The present commercial applications of catalytic combustion are briefly reviewed. Difficulties still hinder the commercial development of this type of combustion as an NO_x control technique. The problems are addressed by both academia and industry. The relevant activities of Gaz de France and GASTEC, both involved in several projects supported by the European Union, are described.     

Physicochemical properties of talc ore from three deposits of Lamal Pougue area (Yaounde Pan-African Belt, Cameroon), in relation to industrial uses

Three talc deposits were discovered at Ngoung, Lamal Pougue and Bibodi Lamal (Cameroon). They derived from ultramafic rocks and are enclosed in a Pan-African garnet and muscovite-bearing mica schist of the Yaoundé series. The physico-chemical properties of these talc deposits have been investigated by different techniques including Scanning Electron and Transmission Microscopy (SEM and TEM), chemical analyses, X-ray diffraction (XRD), infrared spectroscopy, particle size analysis by laser diffraction and low temperature gas absorption–desorption. The mineralogical composition deduced from XRD is wide (talc + chlorite + tremolite ± anthophyllite ± chromite ±serpentine ± brucite ± magnesite ± dolomite), but due to the high talc contents (≈ 90%) the samples are close to monomineralic. SEM studies reveal that all talc deposits comprise bundles of platy talc and a few prismatic crystals of amphiboles and other contaminating minerals. Laser diffraction confirms the coarse particle size of the talc crystals. Mode values are as high as 105–170 μm (except two samples displaying 76 and 42 μm) and d50 ranges from 107 to 25 μm. The values of specific surface area measured by BET and t-plot methods range from 1 to 6 m²/g and are correlated with external specific surface area measured by laser diffraction. Discrepancies from the trend are due to the semi-crystalline texture of the samples and mostly to intra-crystalline structural defects revealed by TEM observations. In infrared spectra, specific absorption bands are distinguished for talc, chlorite, tremolite, carbonates, serpentine, brucite and water. Occasional substitutions in minerals led to a shift in some absorption bands. The chemical composition criteria important for most of the industrial applications such as ceramics and pharmaceutics are closely complied with in untreated samples from these deposits. In summary, high talc proportions, chemical compositions, platy morphology and coarse grain size of its crystals lead to the conclusion that the studied deposits are economically attractive. The data set of the present work is an important tool for choosing the beneficiation methods for specific applications.     

Scale-up of functional properties of pressure-sensitive adhesive from laboratory to industrial plant production: from monomers to label

A waterborne acrylic pressure-sensitive adhesive produced in a commercial plant to label market was successfully developed. In order to reach the required functional properties (i.e. holding time, peel, and loop tack strengths), glass transition temperature, functional monomer content, type of surfactant, and reaction temperature were optimized. A proper balance of wetting and thickening agents content was found taking into consideration their significant unfavorable effect on functional properties.     

Many pathways in laboratory evolution can lead to improved enzymes: how to escape from local minima

Directed evolution is a method to tune the properties of enzymes for use in organic chemistry and biotechnology, to study enzyme mechanisms, and to shed light on darwinian evolution in nature. In order to enhance its efficacy, iterative saturation mutagenesis (ISM) was implemented. This involves: 1) randomized mutation of appropriate sites of one or more residues; 2) screening of the initial mutant libraries for properties such as enzymatic rate, stereoselectivity, or thermal robustness; 3) use of the best hit in a given library as a template for saturation mutagenesis at the other sites; and 4) continuation of the process until the desired degree of enzyme improvement has been reached. Despite the success of a number of ISM-based studies, the question of the optimal choice of the many different possible pathways remains unanswered. Here we considered a complete 4-site ISM scheme. All 24 pathways were systematically explored, with the epoxide hydrolase from Aspergillus niger as the catalyst in the stereoselective hydrolytic kinetic resolution of a chiral epoxide. All 24 pathways were found to provide improved mutants with notably enhanced stereoselectivity. When a library failed to contain any hits, non-improved or even inferior mutants were used as templates in the continuation of the evolutionary pathway, thereby escaping from the local minimum. These observations have ramifications for directed evolution in general and for evolutionary biological studies in which protein engineering techniques are applied.     

Hydroxyapatite/tricalcium silicate composites cement derived from novel two-step sol-gel process with good biocompatibility and applications as bone cement and potential coating materials

Tricalcium silicate (C₃S) and hydroxyapatite (HAp) composites were fabricated through the sol-gel process. The aim of this research is to improve the biocompatibility of C₃S through HAp addition and study the potential of using this as coating materials. The composites (HAp/C₃S) were characterised by Fourier transform infrared spectrometry, thermal gravity-differential thermal analysis and X-ray diffraction. The working and setting times of cement pastes were tested using Gillmore needle. Mechanical properties were examined by nanoindentation and material testing system. In vitro biocompatibility of the materials were studied by cell attachment and viability of L929 and MG-63 cells. HAp/C₃S as a coating material on gelatin film were measured with the surface roughness and imaged by scanning electron microscope. With the addition of HAp, no undesirable free CaO was detected with the synthesis by the sol-gel preparation. The pH values of HAp added groups were between 7.54 and 8.76, which were much lower than pure C₃S group (pH?=?11.75). For in vitro studies, the presence of HAp could effectively enhance the cell attachment and viability of both L929 and MG-63 cells grown in the extract or directly on the composites. However, the mechanical properties of the composites were impaired as compared to pure C₃S. Lastly, HAp/C₃S cement could be evenly coated on gelatin film. HAp is successfully demonstrated to improve C₃S biocompatibility with this new composites HAp/C₃S. C-75 (75% C₃S and 25% HAp), in particular, has good biocompatibility, relatively high compressive strength and can be uniformly coated onto gelatin film. Thus, C-75 is a promising material for further investigation as a coating on other biopolymers.     

The use of solid residues derived from different industrial activities to obtain calcium silicates for use as insulating construction materials

Calcium silicates have obtained through solid state reaction of the different residues generated in various industrial activities. As a source of calcium oxide: marble, mussel shells, and the reagent commercial calcium hydroxide were used. The source of silica was biomass ash and fired ceramic residue formed by crushing pieces of broken and defective ceramic products from a brick factory (chamotte). From the raw materials, biomass ash and marble, biomass ash and commercial calcium hydroxide, and chamotte and crushed mussel shell dust, mixed in a molar ratio CaO:SiO₂ 1:1 and sintered at 1100 °C (24 h), calcium silicates such as wollastonite, gehlenite and larnite were obtained. Both the raw materials and the synthesized material were characterized by XRD, XRF and TGA-DTA. In order to use the calcium silicates obtained as low temperature thermal insulating ceramic materials, the materials obtained were compressed under uniaxial loading at 81.7 MPa to obtain bricks measuring 60 mm × 30 mm × 10 mm. The properties of the bricks were studied. The ceramic materials present conductivity values between 0.10 W/m² K and 0.18 W/m² K and compressive strength of 29.8-59.3 MPa, respectively. The bricks met the UNE guidelines for use as low-temperature structural insulation ceramics.