Large‐Grained Perovskite Films Enabled by One‐Step Meniscus‐Assisted Solution Printing of Cross‐Aligned Conductive Nanowires for Biodegradable Flexible Solar Cells

Increasing performance demand associated with the short lifetime of consumer electronics has triggered fast growth in electronic waste, leading to serious ecological challenges worldwide. Herein, a robust strategy for judiciously constructing flexible perovskite solar cells (PSCs) that can be conveniently biodegraded is reported. The key to this strategy is to capitalize on meniscus‐assisted solution printing (MASP) as a facile means of yielding cross‐aligned silver nanowires in one‐step, which are subsequently impregnated in a biodegradable elastomeric polyester. Intriguingly, the as‐crafted hybrid biodegradable electrode greatly constrains the solvent evaporation of the perovskite precursor solution, thereby generating fewer nuclei and in turn resulting in the deposition of a large‐grained dense perovskite film that exhibits excellent optoelectronic properties with a power conversion efficiency of 17.51% in PSCs. More importantly, the hybrid biodegradable electrode‐based devices also manifest impressive robustness against mechanical deformation and can be thoroughly biodegraded after use. These results signify the great potential of MASP for controllably assembling aligned conductive nanomaterials for biodegradable electrodes. As such, it represents an important endeavor toward environmentally friendly, multifunctional and flexible electronic, optoelectronic, photonic, and sensory materials and devices.     

A novel natural product compound enhances cAMP-regulated chloride conductance of cells expressing CFTR[delta]F508

BACKGROUND: Cystic fibrosis (CF) results from mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene, which encodes a chloride channel localized at the plasma membrane of diverse epithelia. The most common mutation leading to CF, Delta F508, occurs in the first nucleotide-binding domain (NBD1) of CFTR. The Delta F508 mutation disrupts protein processing, leading to a decreased level of mutant channels at the plasma membrane and reduced transepithelial chloride permeability. Partial correction of the Delta F508 molecular defect in vitro is achieved by incubation of cells with several classes of chemical chaperones, indicating that further investigation of novel small molecules is warranted as a means for producing new therapies for CF. MATERIALS AND METHODS: The yeast two-hybrid assay was used to study the effect of CF-causing mutations on the ability of NBD1 to self-associate and form dimers. A yeast strain demonstrating defective growth as a result of impaired NBD1 dimerization due to Delta F508 was used as a drug discovery bioassay for the identification of plant natural product compounds restoring mutant NBD1 interaction. Active compounds were purified and the chemical structures determined. The purified compounds were tested in epithelial cells expressing CFTR Delta F508 and the resulting effect on transepithelial chloride permeability was assessed using short-circuit chloride current measurements. RESULTS: Wild-type NBD1 of CFTR forms homodimers in a yeast two-hybrid assay. CF-causing mutations within NBD1 that result in defective processing of CFTR (Delta F508, Delta I507, and S549R) disrupted NBD1 interaction in yeast. In contrast, a CF-causing mutation that does not impair CFTR processing (G551D) had no effect on NBD1 dimerization. Using the yeast-based assay, we identified a novel limonoid compound (TS3) that corrected the Delta F508 NBD1 dimerization defect in yeast and also increased the chloride permeability of Fisher Rat Thyroid (FRT) cells stably expressing CFTR Delta F508. CONCLUSION: The establishment of a phenotype for the Delta F508 mutation in the yeast two-hybrid system yielded a simple assay for the identification of small molecules that interact with the mutant NBD1 and restore dimerization. The natural product compound identified using the system (TS3) was found to increase chloride conductance in epithelial cells to an extent comparable to genistein, a known CFTR activator. The yeast system will thus be useful for further identification of compounds with potential for CF drug therapy.     

Acidosis Activation of the Proton-Sensing GPR4 Receptor Stimulates Vascular Endothelial Cell Inflammatory Responses Revealed by Transcriptome Analysis

Acidic tissue microenvironment commonly exists in inflammatory diseases, tumors, ischemic organs, sickle cell disease, and many other pathological conditions due to hypoxia, glycolytic cell metabolism and deficient blood perfusion. However, the molecular mechanisms by which cells sense and respond to the acidic microenvironment are not well understood. GPR4 is a proton-sensing receptor expressed in endothelial cells and other cell types. The receptor is fully activated by acidic extracellular pH but exhibits lesser activity at the physiological pH 7.4 and minimal activity at more alkaline pH. To delineate the function and signaling pathways of GPR4 activation by acidosis in endothelial cells, we compared the global gene expression of the acidosis response in primary human umbilical vein endothelial cells (HUVEC) with varying level of GPR4. The results demonstrated that acidosis activation of GPR4 in HUVEC substantially increased the expression of a number of inflammatory genes such as chemokines, cytokines, adhesion molecules, NF-κB pathway genes, and prostaglandin-endoperoxidase synthase 2 (PTGS2 or COX-2) and stress response genes such as ATF3 and DDIT3 (CHOP). Similar GPR4-mediated acidosis induction of the inflammatory genes was also noted in other types of endothelial cells including human lung microvascular endothelial cells and pulmonary artery endothelial cells. Further analyses indicated that the NF-κB pathway was important for the acidosis/GPR4-induced inflammatory gene expression. Moreover, acidosis activation of GPR4 increased the adhesion of HUVEC to U937 monocytic cells under a flow condition. Importantly, treatment with a recently identified GPR4 antagonist significantly reduced the acidosis/GPR4-mediated endothelial cell inflammatory response. Taken together, these results show that activation of GPR4 by acidosis stimulates the expression of a wide range of inflammatory genes in endothelial cells. Such inflammatory response can be suppressed by GPR4 small molecule inhibitors and hold potential therapeutic value.     

The Ternary Structure of the Double-headed Arrowhead Protease Inhibitor API-A Complexed with Two Trypsins Reveals a Novel Reactive Site Conformation

The double-headed arrowhead protease inhibitors API-A and -B from the tubers of Sagittaria sagittifolia (Linn) feature two distinct reactive sites, unlike other members of their family. Although the two inhibitors have been extensively characterized, the identities of the two P1 residues in both API-A and -B remain controversial. The crystal structure of a ternary complex at 2.48 Å resolution revealed that the two trypsins bind on opposite sides of API-A and are 34 Å apart. The overall fold of API-A belongs to the β-trefoil fold and resembles that of the soybean Kunitz-type trypsin inhibitors. The two P1 residues were unambiguously assigned as Leu⁸⁷ and Lys¹⁴⁵, and their identities were further confirmed by site-directed mutagenesis. Reactive site 1, composed of residues P5 Met⁸³ to P5′ Ala⁹², adopts a novel conformation with the Leu⁸⁷ completely embedded in the S1 pocket even though it is an unfavorable P1 residue for trypsin. Reactive site 2, consisting of residues P5 Cys¹⁴¹ to P5′ Glu¹⁵⁰, binds trypsin in the classic mode by employing a two-disulfide-bonded loop. Analysis of the two binding interfaces sheds light on atomic details of the inhibitor specificity and also promises potential improvements in enzyme activity by engineering of the reactive sites.Protease inhibitors (PIs)⁴ are ubiquitously distributed in all organisms, including plants, animals, and microorganisms (1). They play vital roles in regulating their corresponding proteases, which are involved in many biological processes such as protein digestion, cell signal transmission, inflammation, apoptosis, blood coagulation, and embryogenesis (2). The clinical applications of PIs are widespread, and there is great interest in developing more potent therapeutic PIs for treating human diseases related to cancer (3), pancreatitis (4), thrombosis (5), and AIDS (6). To this end, the soybean Kunitz-type serine proteases inhibitors have been extensively studied (1, 7–11). The inhibitors of this family generally contain 170–200 residues and have two disulfide bonds. Most members have only one reactive site located in the region of residues 60–70 (7, 10, 12–14). However, a few members possess two reactive sites that simultaneously bind two protease molecules and are thus termed double-headed inhibitors (15–18). All of these inhibitors are classified into family I3 of peptidase inhibitors (19). Most members are further grouped into subfamily I3A. However, the double-headed arrowhead PIs API-A and -B are grouped in subfamily I3B because of their very low sequence similarity to other members (19). In contrast to other double-headed PIs such as the Bowman-Birk and ovomucoid inhibitors, which have two identical reactive sites that have evolved by domain shuffling and gene duplication (1, 20–25), both API-A and -B have two distinct reactive sites.API-A and -B were first purified from the tubers of Sagittaria sagittifolia (Linn) in 1979 (26). Both consist of 179 residues with three disulfide bonds and can inhibit a variety of serine proteases, including trypsin, chymotrypsin, and porcine tissue kallikrein (17, 26–28). Although the sequence identity of API-A and -B is as high as 91%, their inhibitory specificities differ. The former can bind one molecule of trypsin and one molecule of chymotrypsin, whereas the latter can simultaneously bind two molecules of trypsin (26). The two P1 residues of the reactive sites of API-A and -B were first predicted to be Lys⁴⁴ and Arg⁷⁶ based on their surrounding sequences, which are similar to those of the reactive sites of bovine pancreas trypsin inhibitor and soybean Kunitz trypsin inhibitor (29). However, their identities were later revised to Arg⁷⁶ and Leu⁸⁷ (for API-A) or Lys⁸⁷ (for API-B) based on results from sited-directed mutagenesis studies (30).To clarify these controversies, we solved the crystal structure of API-A in complex with two molecules of bovine trypsin. To the best of our knowledge, this is the first report on the three-dimensional structure of the double-headed Kunitz-type trypsin inhibitor in complex with two molecules of protease. On the basis of this structure, the two P1 residues have now been identified as Leu⁸⁷ and Lys¹⁴⁵ for reactive site 1 (RS1) and 2 (RS2), respectively. The results were further confirmed by site-directed mutagenesis. It was earlier shown that the first P1 residue Leu⁸⁷ interacts preferentially with chymotrypsin (30). In our structure, Leu⁸⁷ is snugly embedded in the S1 pocket of trypsin, as a consequence of the broad interface contributed by the surrounding residues. Comprehensive analyses of the two reactive site interfaces have provided functional insights into the novel inhibitory patterns of this unique double-headed protease inhibitor.     

Substitution of Val72 residue alters the enantioselectivity and activity of Penicillium expansum lipase

Error-prone PCR was used to create more active or enantioselective variants of Penicillium expansum lipase (PEL). A variant with a valine to glycine substitution at residue 72 in the lid structure exhibited higher activity and enantioselectivity than those of wild-type PEL. Site-directed saturation mutagenesis was used to explore the sequence-function relationship and the substitution of Val72 of P. expansum lipase changed both catalytic activity and enantioselectivity greatly. The variant V72A, displayed a highest enantioselectivity enhanced to about twofold for the resolution of (R, S)-naproxen (E value increased from 104 to 200.7 for wild-type PEL and V72A variant, respectively). In comparison to PEL, the variant V72A showed a remarkable increase in specific activity towards p-nitrophenyl palmitate (11- and 4-fold increase at 25 and 35?°C, respectively) whereas it had a decreased thermostability. The results suggest that the enantioselective variant V72A could be used for the production of pharmaceutical drugs such as enantiomerically pure (S)-naproxen and the residue Val 72 of P. expansum lipase plays a significant role in the enantioselectivity and activity of this enantioselective lipase.     

氮磷添加对亚热带常绿阔叶林土壤氮素矿化的影响

设计了2种处理(即氮添加,100 kg N·hm-2·a-1;氮磷添加,100 kgN·hm-2·a-1+50kgP·hm-2·a-1),研究了氮磷添加对亚热带北部常绿阔叶林土壤无机氮和氮素矿化的影响.结果表明,不同处理0 ～ 10 cm和10 ～ 20 cm土层无机氮(铵态氮+硝态氮)含量年平均值分别为:对照7.27和6.80 mg·kg-1、氮添加13.94和8.92 mg·kg-1、氮磷添加11.20和7.13 mg·kg-1,其中铵态氮分别占90.66％和91.15％、65.78％和72.85％、84.64％和85.08％.不同处理0～10 cm和10 ～20 cm土层的净氨化、净硝化和净氮矿化速率具有相似的季节性变化规律,即夏季氮素净转化速率最高,冬季氮素净转化速率最低,春季和秋季氮素净转化速率有一定差异,但不显著.研究表明,养分添加使土壤年平均净氮矿化速率下降,氮添加使土壤硝化速率下降,氨化速率上升;而氮磷添加使硝化速率上升,氨化速率下降.养分添加对森林生态系统的氮动态影响效应尚需长期定位观测.     

成年大鼠气管插管方法的改良

目的寻找一种较好的成年大鼠气管插管方法;方法对比明视经口气管内插管法与逆行导管引导插管法的成功率及并发症;结果明视经口气管内插管法的成功率为100%,逆行导管引导插管法的成功率为87%。插管后并发症明显低于逆行导管引导插管法。结论明视经口气管内插管法优于逆行导管引导插管法,值得推广应用。