The conversion of biomass to chemicals and energy is imperative to sustaining our way of life as known to us today. Fossil chemical and energy sources are traditionally regarded as wastes from a ...distant past. Petroleum, natural gas, and coal are not being regenerated in a sustainable manner. However, biomass sources such as algae, grasses, bushes and forests are continuously being replenished. Woody biomass represents the most abundant and available biomass source. Woody biomass is a reliably sustainable source of chemicals and energy that could be replenished at a rate consistent with our needs. The biorefinery is a concept describing the collection of processes used to convert biomass to chemicals and energy. Woody biomass presents more challenges than cereal grains for conversion to platform chemicals due to its stereochemical structures. Woody biomass can be thought of as comprised of at least four components: extractives, hemicellulose, lignin and cellulose. Each of these four components has a different degree of resistance to chemical, thermal and biological degradation. The biorefinery concept proposed at ESF (State University of New York — College of Environmental Science and Forestry) aims at incremental sequential deconstruction, fractionation/conversion of woody biomass to achieve efficient separation of major components. The emphasis of this work is on the kinetics of hot-water extraction, filling the gap in the fundamental understanding, linking engineering developments, and completing the first step in the biorefinery processes. This first step removes extractives and hemicellulose fractions from woody biomass. While extractives and hemicellulose are largely removed in the extraction liquor, cellulose and lignin largely remain in the residual woody structure. Xylo-oligomers and acetic acid in the extract are the major components having the greatest potential value for development. Extraction/hydrolysis involves at least 16 general reactions that could be divided into four categories: adsorption of proton onto woody biomass, hydrolysis reactions on the woody biomass surface, dissolution of soluble substances into the extraction liquor, and hydrolysis and dehydration decomposition in the extraction liquor. The extraction/hydrolysis rates are significantly simplified when the reactivity of all the intermonomer bonds are regarded as identical within each macromolecule, and the overall reactivity are identical for all the extractable macromolecules on the surface. A pseudo-first order extraction rate expression has been derived based on concentrations in monomer units. The reaction rate constant is however lower at the beginning of the extraction than that towards the end of the extraction. Furthermore, the H-factor and/or severity factor can be applied to lump the effects of temperature and residence time on the extraction process, at least for short times. This provides a means to control and optimize the performance of the extraction process effectively.
Heterointerface engineering can be used to develop excellent catalysts through electronic coupling effects between different components or phases. As one kind of promising Pt‐free electrocatalysts ...for hydrogen evolution reaction (HER), pure‐phased metal phosphide exhibits the unfavorable factor of strong or weak H*‐adsorption performance. Here, 6 nm wall‐thick Ni2P–NiP2 hollow nanoparticle polymorphs combining metallic Ni2P and metalloid NiP2 with observable heterointerfaces are synthesized. It shows excellent catalytic performance toward the HER, requiring an overpotential of 59.7 mV to achieve 10 mA cm−2 with a Tafel slope of 58.8 mV dec−1. Density functional theory calculations verify electrons' transfer from P to Ni at the heterointerfaces, which decreases the absolute value of H* adsorption energy and simultaneously enhance electronic conductivity. That is, the heterojunctions balance the metallic Ni2P and the metalloid NiP2 to form an optimized phosphide polymorph catalyst for the HER. Furthermore, this polymorph combination is used with NiFe‐LDH nanosheets to form an alkaline electrolyzer. It shows highly desirable electrochemical properties, which can reach 10 mA cm−2 in 1 m KOH at 1.48 V and be driven by an AAA battery with a nominal voltage of 1.5 V. The work about interfacial charge transfer might provide an insight into designing excellent polymorph catalysts.
6‐nm‐thin‐wall Ni2P–NiP2 hollow nanoparticles with highly efficient hydrogen evolution reaction (HER) activity are designed. The electron transfer from P to Ni at the Ni2P–NiP2 interfaces can optimize the ΔGH* value of Ni2P–NiP2. This Ni2P–NiP2 polymorph combined with NiFe‐LDH nanosheets can be used as an alkaline electrolyzer driven by a 1.5 V (AAA) battery.
The Hippo-YAP (Yes-associated protein) pathway is an evolutionarily and functionally conserved regulator of organ size and growth with crucial roles in cell proliferation, apoptosis, and ...differentiation. This pathway has great potential for therapeutic manipulation in different disease states and to promote organ regeneration. In this Review, we summarize findings from the past decade revealing the function and regulation of the Hippo-YAP pathway in cardiac development, growth, homeostasis, disease, and regeneration. In particular, we highlight the roles of the Hippo-YAP pathway in endogenous heart muscle renewal, including the pivotal role of the Hippo-YAP pathway in regulating cardiomyocyte proliferation and differentiation, stress response, and mechanical signalling. The human heart lacks the capacity to self-repair; therefore, the loss of cardiomyocytes after injury such as myocardial infarction can result in heart failure and death. Despite substantial advances in the treatment of heart failure, an enormous unmet clinical need exists for alternative treatment options. Targeting the Hippo-YAP pathway has tremendous potential for developing therapeutic strategies for cardiac repair and regeneration for currently intractable cardiovascular diseases such as heart failure. The lessons learned from cardiac repair and regeneration studies will also bring new insights into the regeneration of other tissues with limited regenerative capacity.
Enzymes or proteins are commonly present in oligomeric forms for active biological functions. The formation of protein oligomers, either in nature or by artificial means, can take place via covalent ...bonding or through weak-bond-network associations. Disulfide bonds are more common in forming covalent protein oligomers. Covalent bound protein oligomers usually have additional elements introduced, while proteins associated through weak-bond-networks usually do not involve any additional bound chemical groups. Proteins are commonly present in stable forms or folds. Oligomerization can occur when stable proteins unfold, creating exposed interfaces for association interactions. One well-known process of weak-bond-network oligomerization is domain swapping (DS). Separating the two touching/interacting domains creates opportunities for similar interactions with different protein molecules, leading to oligomerization. Both disulfide bonding and DS oligomerization can be dynamic (or reversible) at least at low Degree of Polymerizations (DPs). The dynamic nature of the protein oligomerization is important for bioactivity control. The morpheein model and the polymorph model are thus important in quantifying enzyme catalyzed biotransformations. Disulfide bonding and DS can act together to form supramolecules. The formation of supramolecules, such as amyloids, in nature can be benign or harmful. Industrial applications of protein oligomerization exploit the special functions /properties of the resultant supramolecules, such as multiple biofunctions, niche structure, etc..
The scientific community has been seeking cost‐competitive and green solvents with good dissolving capacity for the valorization of lignocellulosic biomass. At this point, deep eutectic solvents ...(DESs) are currently emerging as a new class of promising solvents that are generally liquid eutectic mixtures formed by self‐association (or hydrogen‐bonding interaction) of two or three components. DESs are attractive solvents for the fractionation (or pretreatment) of lignocellulose and the valorization of lignin, owing to the high solubility of lignin in DESs. DESs are also employed as effective media for the modification of cellulose to afford functionalized cellulosic materials, such as cellulose nanocrystals. More interestingly, biomassderived carbohydrates, such as fructose, can be used as one of the constituents of DESs and then dehydrated to 5‐hydroxymethylfurfural in high yield. In this review, a comprehensive summary of recent contribution of DESs to the processing of lignocellulosic biomass and its derivatives is provided. Moreover, further discussion about the challenges of the application of DESs in biomass processing is presented.
Going green: Cost‐competitive and green solvents with good dissolving capacity for the valorization of lingocellulosic biomass are required. This review discusses deep eutectic solvents as green solvents for the valorization of lignocellulosic biomass, which is generally composed of widely available, renewable, and low toxicity/nontoxic compounds.
Using fermentation to replace chemical processes in the production of acetone and butanol depends largely on the availability of inexpensive and abundant raw materials and efficient conversion of ...these materials to solvents. In this study solvent production of Clostridium acetobutylicum ATCC824 from nano-membrane concentrated hemicellulosic hydrolysate was investigated. Alkali pretreatment methods were applied to improve fermentability of nano-membrane concentrated hemicellulosic hydrolysate and solvent production by ATCC824. Results demonstrated that though nanofiltration could remove nearly all small molecular organic acids (acetic acid, formic acid), furfural and HMF, the resulting hydrolysate found to be still inhibiting solvent production of C. acetobutylicum. Solid particles separated from filtering hydrolysate were found not toxic to cells when xylose or glucose was used as carbon resource. Overliming treatment can significantly improve the ultimate butanol concentration to 7 g l−1 from 0.8 g l−1. Providing cells with more carbon source at the final stage of fermentation was found to have no impact on butanol production, but acetic acid and butyric acid production were found to increase significantly. The reasons leading to low solvent yield at later fermentation stages is not cell degeneration, but the toxicity of butanol and inhibitors remaining in the hydrolysate.
Single-atom noble metal catalysts have been widely studied for catalytic oxidation of CO. Regulating the coordination environment of single metal atom site is an effective strategy to improve the ...intrinsic catalytic activity of single atom catalyst. In this work, single atom Pd catalyst supported on Pr-doped CeO2 nanorods was prepared, and the performance and nature of Pr-coordinated atomic Pd site in CO catalytic oxidation are systematically investigated. The structure characterization using AC-HAADF-STEM, EXAFS, XRD and Raman spectroscopy demonstrate the formation of single atom Pd site and abundant surface oxygen vacancies on the surface of Pr-doped CeO2 nanorod. With the combination of the XPS characterization and DFT calculations, the oxidation state of Pd on Pr-doped CeO2 nanorod is determined lower than that on CeO2 nanorod. The turnover frequency of CO oxidation is markedly increased from 8.4 × 10−3 to 31.9 × 10−3 s with Pr-doping at 130 ºC and GHSV of 70,000 h−1. Combined with kinetic studies, DRIFT and DFT calculations, the doped-Pr atoms reduced the formation energy of oxygen vacancies and generate more oxygen vacancies around the atomically dispersed Pd sites on the surface of cerium oxide, which reduces the dissociation energy of oxygen, thereby accelerating the reaction rate of CO oxidation.
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•Atomically dispersed Pd is anchored on the (110) crystal plane of the PrCeO2 nanorod support.•Oxygen vacancies of CeO2 nanorods was controllably tuned by Pr doping.•Pr doping enhances the intrinsic activity of its coordinated Pd single atom.•Generated oxygen vacancies by Pr introducing considerably promote the reaction between CO and the lattice oxygen.
Abstract
Aims
Inhibition of proprotein convertase subtilisin/kexin type 9 (PCSK9) has emerged as a novel therapy to treat hypercholesterolaemia and related cardiovascular diseases. This study ...determined if PCSK9 can regulate infarct size, cardiac function, and autophagy during ischaemia.
Methods and results
Mice hearts were subjected to left coronary artery (LCA) occlusion. There was intense expression of PCSK9 in the zone bordering the infarct area in association with marked cardiac contractile dysfunction in the wild-type mice. This region also revealed intense autophagy. To assess the role of PCSK9 in the evolution of infarct size and function and development of autophagy, we used wild-type mice pre-treated with two different PCSK9 inhibitors (Pep2-8 and EGF-A) or mice lacking PCSK9 gene. Both strategies resulted in smaller infarcts and improved cardiac function following LCA ligation. PCSK9 inhibition also markedly reduced autophagy. Relationship between myocardial ischaemia and PCSK9 expression and autophagy was examined in cultured mouse cardiomyocytes. Exposure of cardiomyocytes to hypoxia resulted in prompt PCSK9 expression and autophagy signals; both were blocked by HIF-1α siRNA. Further, treatment of cardiomyocytes with recombinant PCSK9 during hypoxia induced, and treatment with PCSK9 siRNA reduced, autophagy suggesting a possible role of PCSK9 in the determination of autophagy. Other studies revealed activation of ROS-ATM-LKB1-AMPK axis as a possible mechanism of PCSK-induced autophagy. Hearts of humans with recent infarcts also showed expression of PCSK9 and autophagy in the border zone-similar to that in the infarcted mouse heart.
Conclusion
PCSK9 is up-regulated in the ischaemic hearts and determines development of infarct size, cardiac function, and autophagy.
Recently, valorization of lignocellulosic biomass, the most abundantly available biomass raw material on the Earth, to biofuels and chemicals has attracted great attention worldwide for the purpose ...of reducing our overwhelming reliance on the non-renewable petroleum resources. γ-Valerolactone (GVL) has recently been hailed as a versatile building block which can be derived from renewable lignocellulosic biomass resource for energy, chemical and material sectors. In this review, focus was principally put on the applications of GVL as a renewable carbon source for green solvents and transportation fuels. In addition, advances in the GVL production through selective reduction of commercial or biomass-derived levulinic acid (LA) and its esters using various hydrogen sources, mainly including molecule H2, formic acid (FA) and alcohols, have been carefully summarized. Moreover, assessment of the relative merits of different hydrogen sources for the GVL production has also been performed.
Disturbance induced by stress relief has a significant effect on the laboratory properties of rocks in high in situ stress regions. A better understanding of its mechanism can help evaluate rock ...properties in regions such as the Tibetan Plateau. In this study, the progressive failure process of gneiss with high disturbance in the eastern Himalayas was explored using triaxial tests, acoustic emission minoring, X-ray computerised tomography (CT), and three-dimensional reconstruction. We established a grading standard to evaluate the impact of disturbances on the mechanical properties of Eastern Himalayas gneiss. With an increase in the degree of disturbance, the compressive strength c and φ decreased. The disturbance exerted a greater influence on the frictional strength than cohesion. In addition, the frictional strength cannot be fully mobilised in gneiss with a high disturbance, which is supported by the unchanged normalised crack initiation stress and the reduction of shear cracks. The internal fracture network reconstructed by CT scanning indicates that the fracture modes of gneiss are determined by the disturbance. With the advancement of disturbance, the main failure mode of gneiss is transformed from shear sliding failure controlled by foliation into splitting failure controlled by microcracks.
•Disturbance caused by stress significantly affects the progressive failure of gneiss.•Disturbance leads to more loss and inadequate mobilization of frictional strength.•The failure mode of disturbed gneiss is transformed from shear sliding to splitting.
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