瑞士北部农田周围野花地小型兽类种群结构特征的研究

目的评价野花地等生态保留带对小型兽类种群动态的影响. 方法我们在瑞士西北部选择3个野花地样地,采用标志重捕方法对普通田鼠种群结构特征和数量动态进行系统地研究.结果生态保留带适合于小型兽类特别是普通田鼠的生存,当周围耕地或农田受到人类干扰时普通田鼠和其他避难鼠种可生存在野花地中,但是,种群数量只有临时达到高峰.在3个野花地间普通田鼠种群数量有所差异,但是具有相同的季节性变化趋势,一般在春季随着植物盖度和食物丰富度的增加,种群数量也开始增加,中夏达到最高水平.秋季种群数量开始下降,但是进入冬季的个体数量相对也高.种群中雌雄个体年龄结构之间有明显的差异,雄性中亚成体的数量比雌性多,雌性中成体的数量比雄性多( χ2 =44.09, df=10, P< 0. 0 0 1, n=236).幼体的数量和繁殖期的雌性个体数量相关(r= 0.894, P<0. 000 1,n = 12), 亚成体数量和繁殖前期雌性数量相关(r= 0.893, P = 0.002, n=12), 繁殖期雌性数量和繁殖期雄性数量相关(r =0.99,P<0.0001,n=12). 种群性比基本保持1∶ 1,但具有月间波动趋势.结论生态保留带为小型兽类提供比较好的栖息地、食物、繁殖和隐蔽空间,因此,普通田鼠占优势地位并且种群数量有季节性变动趋势.     

Marked hypocalcemia after tocolytic magnesium sulphate therapy

Symptomatic hypocalcemia has been reported infrequently in association with magnesium sulfate (MgSO (4)) tocolytic therapy. We report a 38-year-old woman who presented in preterm labor at 24 3/7 weeks. Twenty hours after starting MgSO (4), she developed chest pain. Studies revealed therapeutic serum Mg level, total serum calcium (Ca) = 5.5 mg/dL, 24-hour urine Ca = 763.9 mg, and low serum uric acid and phosphate levels. All studies corrected day 1 postpartum; urine Ca level corrected on day 2. Even short courses of MgSO (4) can result in severe hypocalcemia, raising the question of whether Ca levels should be routinely monitored.     

Pregnancy outcome in patients with previous uterine rupture

BACKGROUND: To review the outcome of subsequent pregnancies in conservatively managed cases of uterine rupture. METHODS: Charts of patients with full thickness uterine rupture in the past 25 years were reviewed and information on subsequent pregnancies was extracted from maternal and neonatal charts. RESULTS: Thirty-seven patients with uterine rupture were identified; the uterus was scarred in 62.2%. Ruptures were repaired in 26 (70.3%). Twelve patients subsequently conceived (24 pregnancies), with recurrence in 8/24 (33.3%) pregnancies or 5/12 (41.7%) patients. Patients with recurrence had a shorter median interval from previous rupture (2 versus 5 years), a higher incidence of previous longitudinal ruptures (60.0% versus 0.0%), and the median gestational age at the preceding rupture was lower without reaching statistical significance (34 versus 38 weeks; p = 0.209). CONCLUSIONS: Longitudinal ruptures and short intervals between rupture and subsequent pregnancy predispose to recurrence of uterine rupture.     

A Review of X-ray Photoelectron Spectroscopy Technique to Analyze the Stability and Degradation Mechanism of Solid Oxide Fuel Cell Cathode Materials

Nondestructive characterization of solid oxide fuel cell (SOFC) materials has drawn attention owing to the advances in instrumentation that enable in situ characterization during high-temperature cell operation. X-ray photoelectron spectroscopy (XPS) is widely used to investigate the surface of SOFC cathode materials because of its excellent chemical specificity and surface sensitivity. The XPS can be used to analyze the elemental composition and oxidation state of cathode layers from the surface to a depth of approximately 5–10 nm. Any change in the chemical state of the SOFC cathode at the surface affects the migration of oxygen ions to the cathode/electrolyte interface via the cathode layer and causes performance degradation. The objective of this article is to provide a comprehensive review of the adoption of XPS for the characterization of SOFC cathode materials to understand its degradation mechanism in absolute terms. The use of XPS to confirm the chemical stability at the interface and the enrichment of cations on the surface is reviewed. Finally, the strategies adopted to improve the structural stability and electrochemical performance of the LSCF cathode are also discussed.     

High performance and remarkable cyclic stability of a nanostructured RGO–CNT-WO3 supercapacitor electrode

One of the most pressing concerns in today''s power networks is ensuring that consumers (both home and industrial) have access to efficient and long-lasting economic energy. Due to improved power accessibility and high specific capacitance without deterioration over long working times, supercapacitor-based energy storage systems can be a viable solution to this problem. So, here, tungsten trioxide (WO₃) nanocomposites containing reduced graphene oxide and carbon nanotubes i.e. (RGO-WO₃), (CNT-WO₃), and (RGO–CNT-WO₃), as well as pure WO₃ nanostructures as electrode materials, were synthesized using a simple hydrothermal process. The monoclinic phase of WO₃ with high diffraction peaks is visible in X-ray diffraction analysis, indicating good crystallinity of all electrode materials. Nanoflowers of WO₃ were well-decorated on the RGO/CNTs conductive network in SEM micrographs. In a three-electrode system, the specific capacitance of the RGO–CNT-WO₃ electrode is 691.38 F g⁻¹ at 5 mV s⁻¹ and 633.3 F g⁻¹ at 2 A g⁻¹, which is significantly higher than that of pure WO₃ and other binary electrodes. Furthermore, at 2 A g⁻¹, it achieves a coulombic efficiency of 98.4%. After 5000 cycles, RGO–CNT-WO₃ retains 89.09% of its capacitance at 1000 mV s⁻¹, indicating a promising rate capability and good cycling stability performance.

One of the most pressing concerns in today''s power networks is ensuring that consumers (both home and industrial) have access to efficient and long-lasting economic energy.     

The Effect of Pressure-Induced Mechanical Stretch on Vascular Wall Differential Gene Expression

High blood pressure is responsible for the modulation of blood vessel morphology and function. Arterial hypertension is considered to play a significant role in atherosclerotic ischaemic heart disease, stroke and hypertensive nephropathy, whereas high venous pressure causes varicose vein formation and chronic venous insufficiency and contributes to vein bypass graft failure. Hypertension exerts differing injurious forces on the vessel wall, namely shear stress and circumferential stretch. Morphological and molecular changes in blood vessels ascribed to elevated pressure consist of endothelial damage, neointima formation, activation of inflammatory cascades, hypertrophy, migration and phenotypic changes in vascular smooth muscle cells, as well as extracellular matrix imbalances. Differential expression of genes encoding relevant factors including vascular endothelial growth factor, endothelin-1, interleukin-6, vascular cell adhesion molecule, intercellular adhesion molecule, matrix metalloproteinase-2 and -9 and plasminogen activator inhibitor-1 has been explored using ex vivo cellular or organ stretch models and in vivo experimental animal models. Identification of pertinent genes may unravel new therapeutic strategies to counter the effects of pressure-induced stretch on the vessel wall and hence minimise its notable complications.     

Electronic,mechanical, optical and photocatalytic properties of two-dimensional Janus XGaInY (X,Y ;= S,Se and Te) monolayers

Janus monolayers with breaking out-of-plane structural symmetries and spontaneous electric polarizations offer new possibilities in the field of two-dimensional materials. Due to the depletion of fossil fuels and serious environmental problems, there has been a growing interest in the conversion of water and solar energy into H₂ fuels in recent years. In this research, Janus XGaInY (X, Y = S, Se and Te) monolayers are predicted as promising solar-water-splitting photocatalysts. Based on first-principles calculations, the electronic, mechanical, optical and photocatalytic properties of Janus XGaInY (X, Y = S, Se and Te) monolayers are investigated. These Janus monolayers are structurally stable semiconductors with indirect bandgaps, except for SGaInSe, SGaInTe, TeGaInS and SeGaInTe. Their energy bandgaps extend from 0.74 to 2.66 eV at a hybrid density functional level, which is crucial for broadband photoresponses. Moreover, these Janus monolayers not only show strong light absorption coefficients greater than 10⁴ cm⁻¹ in the visible and ultraviolet regions but possess suitable band edge positions for water splitting. Our findings reveal that these Janus monolayers have a potential for application in the fields of optoelectronic and photocatalysis.

Janus monolayers with breaking out-of-plane structural symmetries and spontaneous electric polarizations offer new possibilities in the field of two-dimensional materials.     

A highly selective pyridoxal-based chemosensor for the detection of Zn(ii) and application in live-cell imaging; X-ray crystallography of pyridoxal-TRIS Schiff-base Zn(ii) and Cu(ii) complexes

In a simple, one-step reaction, we have synthesized a pyridoxal-based chemosensor by reacting tris(hydroxymethyl)aminomethane (TRIS) together with pyridoxal hydrochloride to yield a Schiff-base ligand that is highly selective for the detection of Zn(ii) ion. Both the ligand and the Zn(ii) complex have been characterized by ¹H & ¹³C NMR, ESI-MS, CHN analyses, and X-ray crystallography. The optical properties of the synthesized ligand were investigated in an aqueous buffer solution and found to be highly selective and sensitive toward Zn(ii) ion through a fluorescence turn-on response. The competition studies reveal the response for zinc ion is unaffected by all alkali and alkaline earth metals; and suppressed by Cu(ii) ion. The ligand itself shows a weak fluorescence intensity (quantum yield, Φ = 0.04), and the addition of zinc ion enhanced the fluorescence intensity 12-fold (quantum yield, Φ = 0.48). The detection limit for zinc ion was 2.77 × 10⁻⁸ M, which is significantly lower than the WHO''s guideline (76.5 μM). Addition of EDTA to a solution containing the ligand–Zn(ii) complex quenched the fluorescence, indicating the reversibility of Zn(ii) binding. Stoichiometric studies indicated the formation of a 2 : 1 L₂Zn complex with a binding constant of 1.2 × 10⁹ M⁻² (±25%). The crystal structure of the zinc complex shows the same hydrated L₂Zn complex, with Zn(ii) ion binding with an octahedral coordination geometry. We also synthesized the copper(ii) complex of the ligand, and the crystal structure showed the formation of a 1 : 1 adduct, revealing 1-dimensional polymeric networks with octahedral coordinated Cu(ii). The ligand was employed as a sensor to detect zinc ion in HEK293 cell lines derived from human embryonic kidney cells grown in tissue culture which showed strong luminescence in the presence of Zn(ii). We believe that the outstanding turn-on response, sensitivity, selectivity, lower detection limit, and reversibility toward zinc ion will find further application in chemical and biological science.

The synthesis, characterization, X-ray crystallography, and live-cell imaging of pyridoxal-TRIS Schiff-base ligand which is selective as a luminescence sensor to detect Zn(ii) ion, and the corresponding Zn(ii) and Cu(ii) complexes are described.     

The SARS-CoV-2 B.1.618 variant slightly alters the spike RBD–ACE2 binding affinity and is an antibody escaping variant: a computational structural perspective

Continuing reports of new SARS-CoV-2 variants have caused worldwide concern and created a challenging situation for clinicians. The recently reported variant B.1.618, which possesses the E484K mutation specific to the receptor-binding domain (RBD), as well as two deletions of Tyr145 and His146 at the N-terminal binding domain (NTD) of the spike protein, must be studied in depth to devise new therapeutic options. Structural variants reported in the RBD and NTD may play essential roles in the increased pathogenicity of this SARS-CoV-2 new variant. We explored the binding differences and structural-dynamic features of the B.1.618 variant using structural and biomolecular simulation approaches. Our results revealed that the E484K mutation in the RBD slightly altered the binding affinity through affecting the hydrogen bonding network. We also observed that the flexibility of three important loops in the RBD required for binding was increased, which may improve the conformational optimization and consequently binding of the new variant. Furthermore, we found that deletions of Tyr145 and His146 at the NTD reduced the binding affinity of the monoclonal antibody (mAb) 4A8, and that the hydrogen bonding network was significantly affected consequently. This data show that the new B.1.618 variant is an antibody-escaping variant with slightly altered ACE2–RBD affinity. Moreover, we provide insights into the binding and structural-dynamics changes resulting from novel mutations in the RBD and NTD. Our results suggest the need for further in vitro and in vivo studies that will facilitate the development of possible therapies for new variants such as B.1.618.

This study explored the binding patterns of the wild type and B.1.618 variant using which revealed that the B.1.618 variant possess a stronger binding affinity for the host ACE2 and escape the neutralizing antibodies.