Myeloperoxidase-induced fibrinogen unfolding and clotting

Due to its unique properties and high biomedical relevance fibrinogen is a promising protein for the development of various matrixes and scaffolds for biotechnological applications. Fibrinogen molecules may form extensive clots either upon specific cleavage by thrombin or in thrombin-free environment, for example, in the presence of different salts. Here, we report the novel type of non-conventional fibrinogen clot formation, which is mediated by myeloperoxidase and takes place even at low fibrinogen concentrations (<0.1 mg/ml). We have revealed fibrillar nature of myeloperoxidase-mediated fibrinogen clots, which differ morphologically from fibrin clots. We have shown that fibrinogen clotting is mediated by direct interaction of myeloperoxidase molecules with the outer globular regions of fibrinogen molecules followed by fibrinogen unfolding from its natural trinodular to a fibrillar structure. We have demonstrated a major role of the Debye screening effect in regulating of myeloperoxidase-induced fibrinogen clotting, which is facilitated by small ionic strength. While fibrinogen in an aqueous solution with myeloperoxidase undergoes changes, the enzymatic activity of myeloperoxidase is not inhibited in excess of fibrinogen. The obtained results open new insights into fibrinogen clotting, give new possibilities for the development of fibrinogen-based functional biomaterials, and provide the novel concepts of protein unfolding.     

超声波辅助提取新疆香梨多糖的工艺研究

为探究新疆香梨多糖最优提取工艺及新疆不同地区香梨多糖提取率的差异,该研究以新疆11个采样点的香梨为原料,采用超声波辅助法提取香梨多糖。考察液料比、提取时间、提取温度、乙醇浓度4个单因素对香梨多糖提取率的影响,并通过响应面试验设计得出最优提取工艺条件。香梨多糖最优的提取工艺为液料比4∶1(mL/g)、超声时间53 min、超声温度48℃、乙醇浓度95%,在最优条件下香梨多糖的提取率为3.45%。在该条件下,新疆11个采样点香梨多糖提取率排序为库尔勒市哈拉苏>库尔勒市区>库尔勒市沙依东>和田市皮山>喀什市巴楚>阿克苏市沙雅>库车市区>喀什市叶城>和田市区>阿克苏市区>喀什市莎车。     

Liquid-Liquid Chromatography Separation of Guaiane-Type Sesquiterpene Lactones from Ferula penninervis Regel & Schmalh. and Evaluation of Their In Vitro Cytotoxic and Melanin Inhibitory Potential

Ferula penninervis Regel & Schmalh. is a perennial plant used in Kazakh traditional folk medicine to treat epilepsy, neurosis, rheumatism, gastroduodenal ulcers, dyspepsia, wounds, abscesses or tumors. The aim of this work was to isolate series of sesquiterpene lactones from a crude methanolic root extract and investigate their in vitro cytotoxic potential against androgen-dependent prostate cancer LNCaP and epithelial prostate PNT2 cells, as well as to evaluate their melanin production inhibitory effects in murine melanoma B16F10 cells stimulated with α-melanocyte-stimulating hormone (αMSH). Two new (penninervin P and penninervin Q) and five known (olgin, laferin, olgoferin, oferin and daucoguainolactone F) guaiane-type sesquiterpene lactones were isolated with the use of a simple and fast liquid-liquid chromatography method. Olgin and laferin showed the most promising cytotoxic effects in LNCaP cells (IC₅₀ of 31.03 and 23.26 μg/mL, respectively). Additionally, olgin, laferin, olgoferin, and oferin (10 μg/mL) potently impaired melanin release (40.67–65.48% of αMSH + cells) without influencing the viability of B16F10 cells. In summary, our findings might indicate that guaiane-type sesquiterpene lactones from F. penninervis could be regarded as promising candidates for further research in discovering new therapeutic agents with anti-prostate cancer and skin depigmentation properties.     

Triple-phase boundary and power density enhancement in thin solid oxide fuel cells by controlled etching of the nickel anode

Fabrication of microporous structures for the anode of a thin film solid oxide fuel cell (SOFC(s)) using controlled etching process has led us to increased power density and increased cell robustness. Micropores were etched in the nickel anode by both wet and electrochemical etching processes. The samples etched electrochemically showed incomplete etching of the nickel leaving linked nickel islands inside the pores. Samples which were wet- etched showed clean pores with no nickel island residues. Moreover, the sample with linked nickel islands in the anode pores showed higher output power density as compared to the sample with clean pores. This enhancement is related to the enlargement of the surface of contact between the fuel-anode-electrolyte (the triple-phase boundary).     

EBSD Characterization of Cryogenically Rolled Type 321 Austenitic Stainless Steel

Metallurgical and Materials Transactions A - Electron backscatter diffraction was applied to investigate microstructure evolution during cryogenic rolling of type 321 metastable austenitic...     

Influence of PTFE as a solid lubricant on the mechanical,electrical, and tribological properties of CF-reinforced PC composites

The objective of this research was to study the effects of polytetrafluoroethylene (PTFE) as a solid lubricant on the mechanical, electrical, and tribological properties of carbon fiber (CF)-reinforced polycarbonate (PC) composites. Samples were prepared by means of single-screw extrusion and injection molding processes. The mechanical tests included tensile, flexural, and failing weight impact tests, while the electrical tests consisted of surface and volume resistivity tests. The tribological testing was conducted under dry sliding conditions using pin-on-disk configuration. The results showed that the addition of CF managed to significantly reduce the electrical resistivity as the CF loading approached 10–15 wt%. The addition of PTFE managed to reduce the resistivity of the composite, that is, from 4.51 to 0.53 × 10 (Ωcm). The incorporation of 15 wt%. CF resulted with an increase of 45% in tensile strength and 51.5% in flexural strength, while the addition of PTFE had a negative impact on both properties. It was shown that PTFE was able to reduce the friction coefficient, μ and wear rate, K up to 0.257 and 6.35 × 10⁶ (mm³/Nm), respectively, which can be attributed to the excellent abilities of PTFE to form transfer film. The composite consisting of 15 wt% CF and 10 wt%. PTFE showed highest improvement in term of electrical resistivity, and is deemed the most suitable composition for this study. Scanning electron microscopy was also carried out to further elucidate the fracture and wear mechanism of the PC/CF/PTFE composites.     

Species diversity of blood-sucking mosquitoes (Diptera: Culicidae) in Tomsk Region

Abstract

This article describes the results of studying the Culicidae species composition in Tomsk region, during 8 years, 2008–2015. The survey revealed 31 mosquito species of five genera, namely Anopheles, Culex, Culiseta, Coquillettidia, Aedes. Dominant, numerous, common and rare species of Aedes genus were detected. The complete list of Culicidae species in Tomsk region was recorded. Ae. annulipes and Ae. sticticus were included in the species composition of Siberia; their presence in Tomsk region had previously been doubted. Some other species were deleted from the list because they were absent at the present time.     

Optimal heat exchanger network synthesis with operability and safety considerations

Research on the optimal design of heat exchanger networks (HENs) has primarily revolved around trading off technical design requirements for aspects of economy, such as capital cost of heat exchangers and utilities. As a result, considerations for safety, operability, and flexibility have received much less attention. This study presents a Pinch Analysis-based methodology that considers the inherent safety and operability aspects of an optimal HEN design. The procedure begins with data extraction, followed by utility targeting that gives due consideration to how each process stream impacts the inherent safety of the HEN. This is made possible via the use of a hot and cold Stream Temperature versus Enthalpy Plot (STEP) that prioritises the inherent safety index (ISI) on top of the heat capacity flow rate (CPs) during simultaneous targeting and design of the HEN. The Pinch temperatures and minimum utilities were determined using STEP. At the same time, the hot and cold stream pairs with higher ISIs and those with lower ISIs were matched together so that safety considerations could be emphasised and precautions taken with a particular heat exchanger. The disturbance propagation path through the HEN and the affected streams were also analysed. Network modification was performed using the downstream path concept in order to reduce disturbance propagation downstream of the HEN. The ?T _min violations and energy penalties from network changes were assessed. Flexibility and structural controllability of each network option were compared. The highest percentage of change in every stream of the network indicates that network is the most flexible, while the index of structural controllability closest to 1 demonstrates that the network is most controllable. Application of this method within an illustrative case study showed that network 3 was the most flexible as it yielded the highest percentage of change at 22 %. It was also the most controllable as it had a controllability index closest to 1.0, i.e. at 0.917.     

Surface Reduced Manganese States as a Source of Oxygen Reduction Activity in BaMnO3

In relation to perovskites, tweaking the oxidation state of the B-site cation is fundamental to controlling the catalytic activity of these materials, thus necessitating a complete characterization of surface oxidation states. Herein, using a combination of atomic-scale imaging and spectroscopic techniques, structure-property correlation in barium manganese oxide (BaMnO₃) is established for the oxygen reduction reaction (ORR). Electron energy loss spectroscopy (EELS) on the synthesized BaMnO₃ find the rods to contain an amorphous surface layer with reduced Mn³⁺ states compared to Mn⁴⁺ states in the bulk. Consequently, the BaMnO₃ rods show electrocatalytic activity for the ORR, which originates from the presence of Mn³⁺ at the rod surface. Furthermore, heating of the samples in air at 300 and 800 °C results in a decrease in the number of Mn³⁺ states, and thus lowering of the ORR activity. This study represents a step-stone study in understanding the mechanism of ORR activity and its association to the Mn³⁺ state at the perovskite's surface, opening up possibilities for further surface engineering and tuning catalytic properties.