Chemical structure of coal macerals in Balmer 10 coal and fusinite from Illinois coal as indicated by reductive alkylation

A Canadian Cretaceous coking coal from the Balmer 10 seam, Fernie, British Columbia, was separated by sink-and-float methods into vitrinite and a semifusinite-rich fraction. A portion of the vitrinite fraction was oxidized in air at 100 °C for 72 h to destroy the coking properties. The fresh vitrinite, oxidized vitrinite, and semifusinite of the Balmer coal, and the fusinite from Illinois coal, were each subjected to the reductive alkylation procedure of Sternberg, to cleave the ether linkages and octylate the products. The oxygen functional groups before and after ether cleavage were determined, as were the extractabilities by benzene of the octylated products. Thus the molecular weights of the benzenesoluble fractions of the octylated cleavage products were: fresh vitrinite 1930, oxidized vitrinite 1830, and fusinite 1490. The molecular-weight distribution of the octylated cleavage products was estimated by volatility analysis, which demonstrated the presence of much lower-molecular-weight material. Dilatation analysis of fresh and oxidized vitrinite showed that after cleavage of the ether linkages with potassium in tetrahydrofuran, the two could be brought to the same state. The dilatation behaviour of semifusinite after cleavage of the ether links and octylation showed only contraction, whereas the oxidized vitrinite treated in a similar manner exhibited a large dilatation.     

A study of drilling performances with minimum quantity of lubricant using fuzzy logic rules

Nowadays the increasing interest to perform machining operations is in dry/near-dry environments. The reason includes health and safety of operator, cost, ease of chip recyclability, etc. However one important process, which is difficult to perform in dry, is drilling. Without coolant, drilling leads to excessive thermal distortion and poor tool life. In order to tackle these conflicting requirements, the essentiality of study on machining performances with minimum quantity lubricant (MQL) becomes important.Fuzzy logic rules, which are derived based on fuzzy set theory, are used to develop fuzzy rule based model (FRBM). The performance of FRBM depends on two different aspects: structures of fuzzy rules and the associated fuzzy sets (membership function distributions, MFDs). The aim of this study is to investigate the performances of FRBMs based on Mamdani and TSK-types of fuzzy logic rules with different shapes of MFDs for prediction and performance analysis of machining with MQL in drilling of aluminum alloy. A comparison of the model predictions with experimental results and those published in the literature shows that FRBM with TSK-type fuzzy rules describes excellent trade-off with experimental measurements.     

A new mesoporous FeBO3 material having dominant surface magnetism

A new mesoporous iron(III) borate material has been synthesized hydrothermally by using supramolecular assembly of cationic (cetyltrimethylammonium bromide, CTAB) or anionic (sodiumdodecyl sulfate, SDS) surfactant as structure directing agent (SDA) during co-condensation of Fe(III) and H₃BO₃ under controlled pH condition. Powder X-ray diffraction, N₂ sorption, HRTEM, FE-SEM-EDS, AAS, FT-IR and UV–Vis spectroscopic tools, Mössbauer and magnetization measurements are used to characterize the nanostructure, porosity, morphology, chemical composition and magnetic properties. Template molecules can be removed from the as-synthesized material by two consecutive HCl–EtOH extraction and the template-free sample showed good surface area with a peak pore width of ca. 2.6 nm. Spectroscopic results suggested the octahedral coordination of Fe(III) in the FeBO₃ framework. Magnetic measurements suggested the coexistence of antiferromagnetic core and the glassy magnetic behavior. The glassy magnetic behavior is ascribed to the dominant surface magnetism for mesoporous FeBO₃. Acid catalytic properties of this material in liquid phase benzylation of mesityline and anisole have been studied.     

Cefuroxime-impregnated calcium phosphates as an implantable delivery system in experimental osteomyelitis

The study aimed to investigate the effectiveness of porous calcium phosphates viz., hydroxyapatite (HAp) and a bi-phasic calcium phosphate (BCP) with predominately β-tricalcium phosphate (β-TCP) prepared by aqueous solution combustion method impregnated with cefuroxime axetil for the treatment of experimental osteomyelitis and compared with parenteral treatment. In vitro release of the drug was tested for its sustained elution characteristics for 21 days in PBS (pH 7.2) and measured by HPLC. In the in vivo study, bone infection was induced in tibia of rabbits by inoculation of 1 ml (3 × 10⁶) CFU Staphylococcus aureus. On the 21st day, after the development of osteomyelitis, six animals were treated by filling the cavity with cefuroxime-impregnated HAp blocks (Group II), six animals with the same drug-impregnated β-TCP (Group III) and in six others, only cefuroxime (15 mg/kg twice daily) was injected parenterally 6 weeks (Group IV). Group I with six animals was kept untreated. Histologically, the signs of infection were found to subside by 3 and 6 weeks. Radiological evaluation with cefuroxime-impregnated HAp and β-TCP pointed out the disappearance of sequestrum and existence of newly formed bony specules. Concentration of cefuroxime in bone and serum as estimated by HPLC showed highest value on day 21 itself which reduced marginally by day 42 in both the groups and these values were higher than minimum inhibitory concentration (MIC) against S. aureus. Our findings suggest that bi-phasic calcium phosphates with predominately β-TCP content is a very efficient carrier material for antibiotic compounds even for refractory infections by S. aureus.     

紫菜酶解产物锌螯合-α-葡萄糖苷酶抑制剂活性肽的研究

研究紫菜酶解α-葡萄糖苷酶抑制活性肽与锌螯合反应的条件,并对锌-螯合-糖苷酶抑制剂活性肽的胃肠消化稳定性进行评价。对条斑紫菜在一定条件下进行内切与外切蛋白酶的复合酶解获得具备α-葡萄糖苷酶高抑制活性的多肽,采用超滤纳滤双膜组合分离后旋转蒸发浓缩冻干,获得的多肽质量浓度为1 mg/mL时对0.5 mg/mL的α-葡萄糖苷酶抑制率达68%;利用α-葡萄糖苷酶抑制活性肽与锌溶液反应进行螯合条件优化,螯合的最佳条件为：时间1.5 h,pH 4.5,温度37 ℃,质量浓度6 mg/mL,得到的锌-螯合-糖苷酶抑制剂活性肽溶液螯合度为25.6%,螯合后对α-葡萄糖苷酶抑制活性提高到79.8%;建立体外胃肠消化模型,以α-葡萄糖苷酶抑制活性为指标,评价制备的锌-螯合-糖苷酶抑制剂活性肽的胃肠消化耐受性,结果表明：经过不同酶与底物比、时间胃消化后α-葡萄糖苷酶抑制活性下降均在7%左右,十二指肠消化后,抑制活性下降均在5%以内,具有良好的胃肠消化稳定活性。     

高抑菌活性物质产生菌的选育、优化及其特性表征

以发酵液对金黄色葡萄球菌的抑菌能力作为指标,从实验室保藏菌株中筛选出一株产抑菌活性物质水平较高的菌株JN-814C,经鉴定其为地衣芽孢杆菌。进一步研究该菌株产生与分泌细菌素的特性,确定其最适培养基为糊精2.5 g/L,酵母粉7.5 g/L,胰蛋白胨10 g/L,氯化钠3g/L,最佳培养条件为培养时间22 h,培养温度37℃,初始pH 7.0,装液量50 mL,接种量2%。通过硫酸铵分级沉淀与DEAE-Sepharose-FF阴离子交换层析可初步纯化得到抑菌活性物质样品。纯化后的抑菌物质对革兰氏阳性菌有较好的拮抗性,对样品进行蛋白酶处理与氨基酸分析,发现其对碱性蛋白酶敏感,组成中谷氨酸含量较高,对温度、酸碱的敏感性较低,因此可基本被确定为一种抑菌肽。     

Filtering Super-Resolution Scan Conversion of Medical Ultrasound Frames

Wireless Personal Communications - In this paper, we consider a challenging problem of reconstruction of high resolution (HR) B-mode ultrasound (US) image by proposing a novel multi-frame based...     

In vitro and in vivo degradability,biocompatibility and antimicrobial characteristics of Cu added iron-manganese alloy

In recent years,iron(Fe)based degradable metal is explored as an alternative to permanent fracture fixation devices.In the present work,copper(Cu)is added in Fe-Mn system to enhance the degradation rate and antimicrobial properties.Fe-Mn-xCu(x=0.9,5 and 10 wt.％)alloys are prepared by the melting-casting-forging route.XRD analysis confirms austenite phase stabilization due to the presence of Mn and Cu.As predicted by Thermo-Calc calculations,Cu rich phase precipitations are noticed along the austen-ite grain boundaries.Degradation behaviours of Cu added Fe-Mn alloys are investigated through static immersion and electrochemical polarization where enhanced degradation is found for higher Cu added alloys.When challenged against E.Coli bacteria,the Fe-Mn-Cu alloy media extract shows a significant bac-tericidal effect compare to the base alloy.In vitro cytocompatibility studies,as determined using MG63 and MC3T3-E1 cell lines,indicate increased cell density as a function of time for all the alloys.When implanted in rabbit femur,the newly developed alloy does not show any kind of tissue necrosis around the implants.Better osteogenesis and higher new bone formation are observed with Fe-Mn-10Cu alloy as evident from micro-computed tomography(μ-CT)and fluorochrome labelling.     

An empirical approach towards characterization of encrypted and unencrypted VoIP traffic

Multimedia Tools and Applications - VoIP traffic classification plays a major role towards network policy enforcements. Characterization of VoIP media traffic is based on codec behaviour. With the...     

Design of efficient lightweight strategies to combat DoS attack in delay tolerant network routing

Delay tolerant networks (DTNs) are characterized by delay and intermittent connectivity. Satisfactory network functioning in a DTN relies heavily on co-ordination among participating nodes. However, in practice, such co-ordination cannot be taken for granted due to possible misbehaviour by relay nodes. Routing in a DTN is, therefore, vulnerable to various attacks, which adversely affect network performance. Several strategies have been proposed in the literature to alleviate such vulnerabilities—they vary widely in terms of throughput, detection time, overhead etc. One key challenge is to arrive at a tradeoff between detection time and overhead. We observe that the existing table-based reactive strategies to combat Denial-of-service (DoS) attacks in DTN suffer from two major drawbacks: high overhead and slow detection. In this paper, we propose three secure, light-weight and time-efficient routing algorithms for detecting DoS attacks (Blackhole and Grey-hole attacks) in the Spray & Focus routing protocol. The proposed algorithms are based on use of a small fraction of privileged (trusted) nodes. The first strategy, called TN, outperforms the existing table-based strategy with 20–30 % lesser detection time, 20–25 % higher malicious node detection and negligible overhead. The other two strategies, CTN_MI and CTN_RF explore the novel idea that trusted nodes are able to utilize each others’ information/experience using their long range connectivity as and when available. Simulations performed using an enhanced ONE simulator reveals that investing in enabling connectivity among trusted nodes (as in CTN_RF) can have significant performance benefits.