酶预处理对棉秆皮和光叶楮皮制浆效果的影响

对棉秆皮和光叶楮皮经过不同酶处理后的制浆效果及漂白性能进行了研究.结果表明在相似的蒸煮工艺下,两种原料表现出较大的制浆差异.经过酶处理后可以显著改善两种原料的制浆性能,降低纸浆卡伯值,以及可以降低蒸煮碱用量.从漂白效果来看,酶处理有助于改善漂白得率,其中以果胶酶和木聚糖酶的单独处理效果明显,白度均可达80％ ISO左右...     

黏合剂结构对胶片及推进剂力学性能的影响

为了阐明黏合剂结构对推进剂力学性能的影响,采用动态力学和单项拉伸试验方法,研究了几种典型聚酯聚醚黏合剂结构对推进剂力学性能的影响。结果表明,在不含增塑剂情况下,聚四氢呋喃(PTHF)胶片具有更高的伸长率,聚己内酯-四氢呋喃嵌段聚酯醚(HTCE)和聚己内酯(PCL)具有更高的强度;PCL、HTCE和PTHF胶片的储能模量(E′)和损耗模量(E″)依次降低,其玻璃化转变温度(T_g)分别为-43.94、-61.99和-66.98℃。增塑剂降低了链段解冻运动过程中的内耗阻力,使胶片的玻璃化温度大幅降低,PTHF、PCL和HTCE的T_g分别为-67.66、-72.27和-77.10℃,PCL的储能模量和损耗模量最高,PTHF储能模量大于HTCE、HTCE和PCL胶片的力学性能优于PTHF。推进剂的T_g由高到低顺序为PTHF、PCL、HTCE,分别为-55.27、-56.16和-57.91℃;PTHF的储能模量最大,在低温下抗冲击性能和韧性最差;HTCE推进剂的储能模量和损耗模量最低,黏合剂体系的弹性较好、损耗较低;PCL的储能模量、损耗模量和内耗峰面积均较高,在宽温度范围内的刚性和冲击韧性较好。     

Lipooligosaccharides from Mycobacteria: Structure,Function, and Synthesis

Mycobacteria produce a number of ‘extractable glycolipids’, which are present at the outer periphery of their cell wall structure. These molecules are believed to play important roles in mycobacteria host interactions, although for many of these species the manner in which they mediate biological events is poorly understood. We summarize here the structures of one class of these molecules (lipooligosaccharides), highlight briefly their biological role, and discuss synthetic work done to access this complex and diverse group of bacterial glycolipids.     

Special Issue: A,B and Z: The Structure,Function and Genetics of Z-DNA and Z-RNA

It is now difficult to believe that a biological function for the left-handed Z-DNA and Z-RNA conformations was once controversial. The papers in this Special Issue, “Z-DNA and Z-RNA: from Physical Structure to Biological Function”, are based on presentations at the ABZ2021 meeting that was held virtually on 19 May 2021 and provide evidence for several biological functions of these structures. The first of its kind, this international conference gathered over 200 scientists from many disciplines to specifically address progress in research involving Z-DNA and Z-RNA. These high-energy left-handed conformers of B-DNA and A-RNA are associated with biological functions and disease outcomes, as evidenced from both mouse and human genetic studies. These alternative structures, referred to as “flipons”, form under physiological conditions, regulate type I interferon responses and induce necroptosis during viral infection. They can also stimulate genetic instability, resulting in adaptive evolution and diseases such as cancer. The meeting featured cutting-edge science that was, for the most part, unpublished. We plan for the ABZ meeting to reconvene in 2022.     

Overview of First-Line and Second-Line Pharmacotherapies for Osteoarthritis with Special Focus on Intra-Articular Treatment

Osteoarthritis (OA) can be defined as the result of pathological processes of various etiologies leading to damage to the articular structures. Although the mechanism of degenerative changes has become better understood due to the plethora of biochemical and genetic studies, the drug that could stop the degenerative cascade is still unknown. All available forms of OA therapy are based on symptomatic treatment. According to actual guidelines, comprehensive treatment of OA should always include a combination of various therapeutic options aimed at common goals, which are pain relief in the first place, and then the improvement of function. Local treatment has become more common practice, which takes place between rehabilitation and pharmacological treatment in the hierarchy of procedures. Only in the case of no improvement and the presence of advanced lesions visible in imaging tests, should surgery be considered. Currently, an increasing number of studies are being published suggesting that intra-articular injections may be as effective or even more effective than non-steroidal anti-inflammatory drugs (NSAIDs) and result in fewer systemic adverse events. The most commonly used preparations are hyaluronic acid (HA), glucocorticosteroids (GS), and also platelet-rich plasma (PRP) in recent years. This review aims to present the mechanism of action and clinical effectiveness of different pharmacological options in relieving pain and improving functions in OA as well as the emerging approach in intra-articular treatment with PRP.     

Manipulating Active Structure and Function of Cationic Antimicrobial Peptide CM15 with the Polysulfonated Drug Suramin: A Step Closer to in Vivo Complexity

Antimicrobial peptides (AMPs) kill bacteria by targeting their membranes through various mechanisms involving peptide assembly, often coupled with disorder-to-order structural transition. However, for several AMPs, similar conformational changes in cases in which small organic compounds of both endogenous and exogenous origin have induced folded peptide conformations have recently been reported. Thus, the function of AMPs and of natural host defence peptides can be significantly affected by the local complex molecular environment in vivo; nonetheless, this area is hardly explored. To address the relevance of such interactions with regard to structure and function, we have tested the effects of the therapeutic drug suramin on the membrane activity and antibacterial efficiency of CM15, a potent hybrid AMP. The results provided insight into a dynamic system in which peptide interaction with lipid bilayers is interfered with by the competitive binding of CM15 to suramin, resulting in an equilibrium dependent on peptide-to-drug ratio and vesicle surface charge. In vitro bacterial tests showed that when CM15 ⋅ suramin complex formation dominates over membrane binding, antimicrobial activity is abolished. On the basis of this case study, it is proposed that small-molecule secondary structure regulators can modify AMP function and that this should be considered and could potentially be exploited in future development of AMP-based antimicrobial agents.     

How Simulations Reveal Dynamics,Disorder, and the Energy Landscapes of Biomolecular Function

Over the last 40 years, the area of computational molecular biophysics has grown and developed to the point where simulations can now provide detailed mechanistic insights, suggest theoretical principles that underpin function, and provide frameworks for understanding and interpreting experimental measurements. The success of molecular simulations has been the result of the unrelenting development of novel theoretical models, exponential growth in computational resources, and advances in structural biology techniques. Through the continued refinement and application of diverse classes of models, general themes in biomolecular dynamics are beginning to surface. In particular, molecular simulations are highlighting the pervasive role that order disorder events play in molecular biology. These dynamic modes of function are transforming our perspective on the role that entropy has in many large-scale biological processes.     

含氟表面活性剂的结构、特性及应用研究

含氟表面活性剂是特种表面活性剂的一类。与传统的表面活性剂相比，由于其具有高表面活性，优良的耐热性和化学稳定性以及卓越的憎水、憎油性能和防污功能，因此含氟表面活性剂已经广泛应用于各个工业领域及家庭用品领域等。本文对含氟表面活性剂的分类结构、特性及应用领域进行简单综述。     

Chitinases and Chitinase-Like Proteins as Therapeutic Targets in Inflammatory Diseases,with a Special Focus on Inflammatory Bowel Diseases

Chitinases belong to the evolutionarily conserved glycosyl hydrolase family 18 (GH18). They catalyze degradation of chitin to N-acetylglucosamine by hydrolysis of the β-(1-4)-glycosidic bonds. Although mammals do not synthesize chitin, they possess two enzymatically active chitinases, i.e., chitotriosidase (CHIT1) and acidic mammalian chitinase (AMCase), as well as several chitinase-like proteins (YKL-40, YKL-39, oviductin, and stabilin-interacting protein). The latter lack enzymatic activity but still display oligosaccharides-binding ability. The physiologic functions of chitinases are still unclear, but they have been shown to be involved in the pathogenesis of various human fibrotic and inflammatory disorders, particularly those of the lung (idiopathic pulmonary fibrosis, chronic obstructive pulmonary disease, sarcoidosis, and asthma) and the gastrointestinal tract (inflammatory bowel diseases (IBDs) and colon cancer). In this review, we summarize the current knowledge about chitinases, particularly in IBDs, and demonstrate that chitinases can serve as prognostic biomarkers of disease progression. Moreover, we suggest that the inhibition of chitinase activity may be considered as a novel therapeutic strategy for the treatment of IBDs.     

Covalent Tethering and Residues with Bulky Hydrophobic Side Chains Enable Self‐Assembly of Distinct Amyloid Structures

Polymorphism is a common property of amyloid fibers that complicates their detailed structural and functional studies. Here we report experiments illustrating the chemical principles that enable the formation of amyloid polymorphs with distinct stoichiometric composition. Using appropriate covalent tethering we programmed self‐assembly of a model peptide corresponding to the [20–41] fragment of human β2‐microglobulin into fibers with either trimeric or dimeric amyloid cores. Using a set of biophysical and biochemical methods we demonstrated their distinct structural, morphological, and templating properties. Furthermore, we showed that supramolecular approaches in which the peptide is modified with bulky substituents can also be applied to modulate the formation of different fiber polymorphs. Such strategies, when applied to disease‐related peptides and proteins, will greatly help in the evaluation of the biological properties of structurally distinct amyloids.     

The Effect of Crowding in the Bay/Fjord Region on the Structure and Reactivities of Polycyclic Aromatic Hydrocarbons and their Metabolites: Quantum Mechanical Studies

Polycyclic aromatic hydrocarbons with a crowded bay region, like benzo[c]phenanthrene, are nonplanar molecules with two helical structures. The bay region diol-epoxides of these PAHs retain the helical structure and therefore have twice as many possible conformations as the diol-epoxides of planar PAHs. Using quantum mechanical methods, it is shown that the conformation where the epoxide oxygen is near the distal ring is more stable than the conformation where it is away. The most stable syn- and anti- diastereomers for the diol-epoxides of five PAHs are computed. Computation of the electrostatic interaction between the epoxide group and the distal ring suggests that it provides the additional stabilization. Comparison is made between planar and nonplanar PAHs and between molecules where the crowding is due to a ring CH or a methyl group. These results suggest that the molecular electrostatic potential in the bay region can effect molecular reactivity.     

The Structure and Function of Next-Generation Gingival Graft Substitutes—A Perspective on Multilayer Electrospun Constructs with Consideration of Vascularization

There is a shortage of suitable tissue-engineered solutions for gingival recession, a soft tissue defect of the oral cavity. Autologous tissue grafts lead to an increase in morbidity due to complications at the donor site. Although material substitutes are available on the market, their development is early, and work to produce more functional material substitutes is underway. The latter materials along with newly conceived tissue-engineered substitutes must maintain volumetric form over time and have advantageous mechanical and biological characteristics facilitating the regeneration of functional gingival tissue. This review conveys a comprehensive and timely perspective to provide insight towards future work in the field, by linking the structure (specifically multilayered systems) and function of electrospun material-based approaches for gingival tissue engineering and regeneration. Electrospun material composites are reviewed alongside existing commercial material substitutes’, looking at current advantages and disadvantages. The importance of implementing physiologically relevant degradation profiles and mechanical properties into the design of material substitutes is presented and discussed. Further, given that the broader tissue engineering field has moved towards the use of pre-seeded scaffolds, a review of promising cell options, for generating tissue-engineered autologous gingival grafts from electrospun scaffolds is presented and their potential utility and limitations are discussed.     

Fabrication, Microstructural Characterization, and Mechanical Properties of Polycrystalline t'-Zirconia

Large-grained (100- to 200-μm), yttria-doped, polycrystalline t '-zirconia ceramics were fabricated by heat-treating presintered samples at temperatures 2100°C. Polarized light microscopy revealed the ferroelastic domain structure in the t ' samples. XRD showed that no monoclinic phase was detected on as-polished, ground and fracture surfaces, or on surfaces while under a tensile stress as high as 400 MPa. By contrast, relative changes occurred in the tetragonal peak intensities, which were attributed to ferroelasatic domain switching. The higher toughness of 3-mol%-Y₂O₃-doped t ' samples (7.7 MPa · m^1/2) compared to that of 8 mol% Y₂O₃ cubic samples (2.4 MPa · m^1/2) was explained in part by ferroelastic domain switching.     

The Latest Breakthroughs in Immunotherapy for Acute Myeloid Leukemia,with a Special Focus on NKG2D Ligands

Acute myeloid leukemia (AML) is a hematological malignancy characterized by clonal expansion of stem and myeloid progenitor cells. Immunotherapy has revolutionized the care for other cancers such as solid tumors and lymphomas, and has the potential to effectively treat AML. There has been substantial progress in the developments of immunotherapeutic approaches for AML over the last several years, including the development of antibodies that further increase the innate immunogenicity of leukemia cells by the inhibition of NKG2D ligand—particularly MICA and MICB—shedding, chimeric proteins such as IL-15 superagonist that expand natural killer (NK) cells, blockers of immunologic checkpoints such as NKG2A, and chemicals that indirectly increase expression of immune stimulatory proteins in leukemia stem cells. Furthermore, cellular therapies have been designed to enable alloreactive immunity by allogeneic NK cells or target leukemia antigens such as mutated NPM1. These immunotherapeutic approaches have demonstrated remarkable efficacies in preclinical studies and have successfully transitioned to early phase clinical trials, to establish safety and initial signal of clinical activity. Here, we briefly discuss some of the most recent and impactful developments in the AML immunotherapy field and provide our perspectives for the future directions of this exciting and new therapeutic opportunity.     

磷杂环戊二烯合成结构独特磷配体催化剂

磷配体的合成、反应和性质的研究已成为有机合成化学和配位化学的主要研究热点之一,它们在配位化学和选择性催化等方面有重要的应用价值。通过大量文献并结合自己的工作,以磷杂环戊二烯合成的磷配体的结构类型为主线,分析归纳了独特结构磷配体的合成及其在催化方面的应用。     

Characterization of the Heat-Stable Proteome during Seed Germination in Arabidopsis with Special Focus on LEA Proteins

During seed germination, desiccation tolerance is lost in the radicle with progressing radicle protrusion and seedling establishment. This process is accompanied by comprehensive changes in the metabolome and proteome. Germination of Arabidopsis seeds was investigated over 72 h with special focus on the heat-stable proteome including late embryogenesis abundant (LEA) proteins together with changes in primary metabolites. Six metabolites in dry seeds known to be important for seed longevity decreased during germination and seedling establishment, while all other metabolites increased simultaneously with activation of growth and development. Thermo-stable proteins were associated with a multitude of biological processes. In the heat-stable proteome, a relatively similar proportion of fully ordered and fully intrinsically disordered proteins (IDP) was discovered. Highly disordered proteins were found to be associated with functional categories development, protein, RNA and stress. As expected, the majority of LEA proteins decreased during germination and seedling establishment. However, four germination-specific dehydrins were identified, not present in dry seeds. A network analysis of proteins, metabolites and amino acids generated during the course of germination revealed a highly connected LEA protein network.     

Synthesis and Pharmacological In Vitro Investigations of Novel Shikonin Derivatives with a Special Focus on Cyclopropane Bearing Derivatives

Melanoma is the deadliest form of skin cancer and accounts for about three quarters of all skin cancer deaths. Especially at an advanced stage, its treatment is challenging, and survival rates are very low. In previous studies, we showed that the constituents of the roots of Onosma paniculata as well as a synthetic derivative of the most active constituent showed promising results in metastatic melanoma cell lines. In the current study, we address the question whether we can generate further derivatives with optimized activity by synthesis. Therefore, we prepared 31, mainly novel shikonin derivatives and screened them in different melanoma cell lines (WM9, WM164, and MUG-Mel2 cells) using the XTT viability assay. We identified (R)-1-(1,4-dihydro-5,8-dihydroxy-1,4-dioxonaphthalen-2-yl)-4-methylpent-3-enyl 2-cyclopropyl-2-oxoacetate as a novel derivative with even higher activity. Furthermore, pharmacological investigations including the ApoToxGlo^TM Triplex assay, LDH assay, and cell cycle measurements revealed that this compound induced apoptosis and reduced cells in the G1 phase accompanied by an increase of cells in the G2/M phase. Moreover, it showed hardly any effects on the cell membrane integrity. However, it also exhibited cytotoxicity against non-tumorigenic cells. Nevertheless, in summary, we could show that shikonin derivatives might be promising drug leads in the treatment of melanoma.     

Receptor–Receptor Interactions and Glial Cell Functions with a Special Focus on G Protein-Coupled Receptors

The discovery that receptors from all families can establish allosteric receptor–receptor interactions and variably associate to form receptor complexes operating as integrative input units endowed with a high functional and structural plasticity has expanded our understanding of intercellular communication. Regarding the nervous system, most research in the field has focused on neuronal populations and has led to the identification of many receptor complexes representing an important mechanism to fine-tune synaptic efficiency. Receptor–receptor interactions, however, also modulate glia–neuron and glia–glia intercellular communication, with significant consequences on synaptic activity and brain network plasticity. The research on this topic is probably still at the beginning and, here, available evidence will be reviewed and discussed. It may also be of potential interest from a pharmacological standpoint, opening the possibility to explore, inter alia, glia-based neuroprotective therapeutic strategies.     

Structure,Function, and Applications of Soybean Calcium Transporters

Glycine max is a calcium-loving crop. The external application of calcium fertilizer is beneficial to the increase of soybean yield. Indeed, calcium is a vital nutrient in plant growth and development. As a core metal ion in signaling transduction, calcium content is maintained in dynamic balance under normal circumstances. Now, eight transporters were found to control the uptake and efflux of calcium. Though these calcium transporters have been identified through genome-wide analysis, only a few of them were functionally verified. Therefore, in this study, we summarized the current knowledge of soybean calcium transporters in structural features, expression characteristics, roles in stress response, and prospects. The above results will be helpful in understanding the function of cellular calcium transport and provide a theoretical basis for elevating soybean yield.