An overview of the chemical composition of biomass

An extended overview of the chemical composition of biomass was conducted. The general considerations and some problems related to biomass and particularly the composition of this fuel are discussed. Reference peer-reviewed data for chemical composition of 86 varieties of biomass, including traditional and complete proximate, ultimate and ash analyses (21 characteristics), were used to describe the biomass system. It was shown that the chemical composition of biomass and especially ash components are highly variable due to the extremely high variations of moisture, ash yield, and different genetic types of inorganic matter in biomass. However, when the proximate and ultimate data are recalculated respectively on dry and dry ash-free basis, the characteristics show quite narrow ranges. In decreasing order of abundance, the elements in biomass are commonly C, O, H, N, Ca, K, Si, Mg, Al, S, Fe, P, Cl, Na, Mn, and Ti. It was identified that the chemical distinctions among the specified natural and anthropogenic biomass groups and sub-groups are significant and they are related to different biomass sources and origin, namely from plant and animal products or from mixtures of plant, animal, and manufacture materials. Respective chemical data for 38 solid fossil fuels were also applied as subsidiary information for clarifying the biomass composition and for comparisons. It was found that the chemical composition of natural biomass system is simpler than that of solid fossil fuels. However, the semi-biomass system is quite complicated as a result of incorporation of various non-biomass materials during biomass processing. It was identified that the biomass composition is significantly different from that of coal and the variations among biomass composition were also found to be greater than for coal. Natural biomass is: (1) highly enriched in Mn > K > P > Cl > Ca > (Mg, Na) > O > moisture > volatile matter; (2) slightly enriched in H; and (3) depleted in ash, Al, C, Fe, N, S, Si, and Ti in comparison with coal. The correlations and associations among 20 chemical characteristics are also studied to find some basic trends and important relationships occurring in the natural biomass system. As a result of that five strong and important associations, namely: (1) C-H; (2) N-S-Cl; (3) Si-Al-Fe-Na-Ti; (4) Ca-Mg-Mn; and (5) K-P-S-Cl; were identified and discussed. The potential applications of these associations for initial and preliminary classification, prediction and indicator purposes related to biomass were also introduced or suggested. However, future detailed data on the phase-mineral composition of biomass are required to explain actually such chemical trends and associations.     

AB‐ and ABC‐type di‐ and triblock copolymers of poly[styrene‐block‐(ε‐caprolactone)] and poly[styrene‐block‐(ε‐caprolactone)‐block‐lactide]: synthesis,characterization and thermal studies

Polystyrene terminated with benzyl alcohol units was employed as a macroinitiator for ring‐opening polymerization of ε‐caprolactone and L ‐lactide to yield AB‐ and ABC‐type block copolymers. Even though there are many reports on the diblock copolymers of poly(styrene‐block‐lactide) and poly(styrene‐block‐lactone), this is the first report on the poly(styrene‐block‐lactone‐block‐lactide) triblock copolymer consisting of two semicrystalline and degradable segments. The triblock copolymers exhibited twin melting behavior in differential scanning calorimetry (DSC) analysis with thermal transitions corresponding to each of the lactone and lactide blocks. The block derived from ε‐caprolactone also showed crystallization transitions upon cooling from the melt. In the DSC analysis, one of the triblock copolymers showed an exothermic transition well above the melting temperature upon cooling. Thermogravimetric analysis of these block copolymers showed a two‐step degradation curve for the diblock copolymer and a three‐step degradation for the triblock copolymer with each of the degradation steps associated with each segment of the block copolymers. The present study shows that it is possible to make pure triblock copolymers with two semicrystalline segments which also consist of degradable blocks. Copyright © 2009 Society of Chemical Industry     

Zero Shrinkage of LTCC by Self-Constrained Sintering

Low shrinkage in x and y direction and low tolerances of shrinkage are an indispensable precondition for high-density component configuration. Therefore, zero shrinkage sintering technologies as pressure-assisted sintering and sacrificial tapes have been introduced in the low-temperature co-fired ceramics (LTCC) production by different manufacturers. Disadvantages of these methods are high costs of sintering equipment and an additional process step to remove the sacrificial tapes. In this article, newly developed self-constrained sintering methods are presented. The new technology, HeraLock^®, delivers LTCC modules with a sintering shrinkage in x and y direction of less than 0.2% and with a shrinkage tolerance of ±0.02% without sacrificial layers and external pressure. Each tape is self-constrained by integration of a layer showing no shrinkage in the sintering temperature range of the LTCC. Large area metallization, integration of channels, cavities and passive electronic components are possible without waviness and camber. Self-constrained laminates are an alternative way to produce zero shrinkage LTCC. They consist of tapes sintering at different temperature intervals. Precondition for a successful production of a self-constrained LTCC laminate is the development of well-adapted material and tapes, respectively. This task is very challenging, because sintering range, high-temperature reactivity and thermal expansion coefficient have to be matched and each tape has to fulfill specific functions in the final component, which requires the tailoring of many properties as permittivity, dielectric loss, mechanical strength, and roughness. A self-constrained laminate is introduced in this article. It consists of inner tapes sintering at especially low-temperature range between 650°C and 720°C and outer tapes with an as-fired surface suitable for thin-film processes.     

Reactive adsorption for the selective dehydration of sugars to furans: Modeling and experiments

5‐hydroxymethylfurfural (HMF) can be produced from the acid‐catalyzed dehydration of fructose, but its yield is limited due to subsequent HMF degradation to side products. A reactive adsorption process is proposed to improve the yield to HMF. Separate experimental single‐component isotherms of fructose, HMF, formic acid, and levulinic acid on carbon BP2000 and reaction kinetics of the fructose dehydration to HMF in aqueous solution of HCl are presented to develop empirical isotherms and kinetic rate constants, respectively. These submodels are subsequently integrated in an adsorptive reactor at a range of temperatures (100–150^°C) with different loadings of adsorbent. It is shown that the adsorbent improves HMF yield compared to the single‐solution phase (adsorbent‐free case). Low temperatures and high‐adsorbent loadings improve HMF yield. Under certain conditions both reactive adsorption and the commonly used reactive extraction can result in a similar improvement in HMF yield. HMF recovery from the solid adsorbent has been identified as a major challenge that can be ameliorated through adsorbent and solvent selection. The framework outlined here can be applied to any aqueous phase chemistry where the desired product is an intermediate in a reaction cascade. © 2013 American Institute of Chemical Engineers AIChE J, 59: 3378–3390, 2013     

Optimization of extracellular lipase production by Debaryomyces hansenii isolates from dry-salted olives using response surface methodology

The lipase production by Debaryomyces hansenii strains isolated from dry-salted olives cv. Thassos was investigated. Glucose, olive oil and pH were essential to obtain a high lipase yield. Optimization of the medium components which enhance lipase production by the strain D. hansenii YLL29 was achieved with the aid of response surface methodology. The composition of the optimized medium to enhance lipase production by D. hansenii is as follows (g/L): yeast extract 5.0, peptone 10, K₂HPO₄ 4.0, MgSO₄·7H₂O 1.0, glucose 13.1, olive oil 19, Tween 80 3.8, and pH 6.4. Practical validation of the optimum medium gave lipase activity 7.44 U/mL, which was 2.28-fold higher than the unoptimized conditions. Under the optimized conditions the twenty D. hansenii isolates showed increased lipase activity fluctuating between 6.00 and 7.44 U/mL. The results corroborated the validity and the effectiveness of the model, as the statistical approaches proved to be suitable in predicting the optimum production medium composition for maximum extracellular lipase yield. The high lipolytic activity of D. hansenii YLL29 (7.44 U/mL) indicates the possible commercial importance of this isolate.     

Probabilistic model for pitting of copper canisters

Copper canisters for the final disposal of spent nuclear fuel are expected to be subject to general (uniform) corrosion and a limited degree of localised damage. Although the canister is expected to be exposed to predominantly active conditions, it is nevertheless prudent to assess the probability of pitting corrosion in passive conditions. A probabilistic pitting model is developed for aerobic conditions in water-saturated bentonite. While aerobic, saturated conditions may be unlikely to occur if saturation is slow or O₂ consumption is fast, these conditions have been assumed as a starting point because of the availability of data. The model samples from environmental conditions use a Monte Carlo approach to predict active or passive conditions. Under passive conditions, the model compares corrosion potentials to breakdown and repassivation potentials to determine pit initiations and deaths, respectively. Pit depth distributions can then be calculated. For the assumed conditions, the model predicts that active conditions dominate 90% of the time while the remaining passive conditions can lead to pitting during the first few years primarily controlled by the availability of oxygen.     

Development of a PROTAC-Based Targeting Strategy Provides a Mechanistically Unique Mode of Anti-Cytomegalovirus Activity

Human cytomegalovirus (HCMV) is a major pathogenic herpesvirus that is prevalent worldwide and it is associated with a variety of clinical symptoms. Current antiviral therapy options do not fully satisfy the medical needs; thus, improved drug classes and drug-targeting strategies are required. In particular, host-directed antivirals, including pharmaceutical kinase inhibitors, might help improve the drug qualities. Here, we focused on utilizing PROteolysis TArgeting Chimeras (PROTACs), i.e., hetero-bifunctional molecules containing two elements, namely a target-binding molecule and a proteolysis-inducing element. Specifically, a PROTAC that was based on a cyclin-dependent kinase (CDK) inhibitor, i.e., CDK9-directed PROTAC THAL-SNS032, was analyzed and proved to possess strong anti-HCMV AD169-GFP activity, with values of EC₅₀ of 0.030 µM and CC₅₀ of 0.175 µM (SI of 5.8). Comparing the effect of THAL-SNS032 with its non-PROTAC counterpart SNS032, data indicated a 3.7-fold stronger anti-HCMV efficacy. This antiviral activity, as illustrated for further clinically relevant strains of human and murine CMVs, coincided with the mid-nanomolar concentration range necessary for a drug-induced degradation of the primary (CDK9) and secondary targets (CDK1, CDK2, CDK7). In addition, further antiviral activities were demonstrated, such as the inhibition of SARS-CoV-2 replication, whereas other investigated human viruses (i.e., varicella zoster virus, adenovirus type 2, and Zika virus) were found insensitive. Combined, the antiviral quality of this approach is seen in its (i) mechanistic uniqueness; (ii) future options of combinatorial drug treatment; (iii) potential broad-spectrum activity; and (iv) applicability in clinically relevant antiviral models. These novel data are discussed in light of the current achievements of anti-HCMV drug development.     

Highly Selective Cobalt‐Catalyzed Hydrovinylation of Styrene

Phosphine complexes of cobalt halide salts activated by diethylaluminum chloride are shown to yield highly active catalysts in the hydrovinylation of styrene, with unprecedented high selectivity to the desired product 3‐phenyl‐1‐butene (3P1B). Double‐bond isomerization, a common problem in codimerization reactions, only occurs after full conversion with these catalyst systems, even at elevated temperature. The most active catalysts are based on cobalt halide species combined with either C₁‐ or C₂‐bridged diphosphines, heterodonor P,N or P,O ligands, flexible bidentate phosphine ligands or monodentate phosphine ligands. Kinetic investigations show an order >1 in catalyst, which indicates either the involvement of dinuclear species in the catalytic cycle or partial catalyst decomposition via a bimolecular pathway.     

Generation and Characterization of a CRISPR/Cas9-Mediated SNAP29 Knockout in Human Fibroblasts

Loss-of-function mutations in the synaptosomal-associated protein 29 (SNAP29) lead to the rare autosomal recessive neurocutaneous cerebral dysgenesis, neuropathy, ichthyosis, and keratoderma (CEDNIK) syndrome. SNAP29 is a soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) protein. So far, it has been shown to be involved in membrane fusion, epidermal differentiation, formation of primary cilia, and autophagy. Recently, we reported the successful generation of two mouse models for the human CEDNIK syndrome. The aim of this investigation was the generation of a CRISPR/Cas9-mediated SNAP29 knockout (KO) in an immortalized human cell line to further investigate the role of SNAP29 in cellular homeostasis and signaling in humans independently of animal models. Comparison of different methods of delivery for CRISPR/Cas9 plasmids into the cell revealed that lentiviral transduction is more efficient than transfection methods. Here, we reported to the best of our knowledge the first successful generation of a CRISPR/Cas9-mediated SNAP29 KO in immortalized human MRC5Vi fibroblasts (c.169_196delinsTTCGT) via lentiviral transduction.     

The Emerging Role of Neutrophils in the Pathogenesis of Thrombosis in COVID-19

Previous studies have shown that COVID-19 leads to thrombotic complications, which have been associated with high morbidity and mortality rates. Neutrophils are the largest population of white blood cells and play a pivotal role in innate immunity. During an infection, neutrophils migrate from circulation to the infection site, contributing to killing pathogens. This mechanism is regulated by chemokines such as IL-8. Moreover, it was shown that neutrophils play an important role in thromboinflammation. Through a diverse repertoire of mechanisms, neutrophils, apart from directly killing pathogens, are able to activate the formation of thrombi. In COVID-19 patients, neutrophil activation promotes neutrophil extracellular trap (NET) formation, platelet aggregation, and cell damage. Furthermore, neutrophils participate in the pathogenesis of endothelitis. Overall, this review summarizes recent progress in research on the pathogenesis of COVID-19, highlighting the role of the prothrombotic action of neutrophils in NET formation.