Security risk assessment: Applying the concepts of fuzzy logic

Chemical process industries (CPI) handling hazardous chemicals in bulk can be attractive targets for deliberate adversarial actions by terrorists, criminals and disgruntled employees. It is therefore imperative to have comprehensive security risk management programme including effective security risk assessment techniques. In an earlier work, it has been shown that security risk assessment can be done by conducting threat and vulnerability analysis or by developing Security Risk Factor Table (SRFT). HAZOP type vulnerability assessment sheets can be developed that are scenario based. In SRFT model, important security risk bearing factors such as location, ownership, visibility, inventory, etc., have been used. In this paper, the earlier developed SRFT model has been modified using the concepts of fuzzy logic. In the modified SRFT model, two linguistic fuzzy scales (three-point and four-point) are devised based on trapezoidal fuzzy numbers. Human subjectivity of different experts associated with previous SRFT model is tackled by mapping their scores to the newly devised fuzzy scale. Finally, the fuzzy score thus obtained is defuzzyfied to get the results. A test case of a refinery is used to explain the method and compared with the earlier work.     

An investigation into the effect of biomass particle size on its torrefaction

Present work examines an important practical aspect of torrefaction that is, the effect of size and shape of biomass on torrefaction. Experiments were conducted on different sizes of Poplar and Oak wood in directly heated torrefaction reactors. Experiments were conducted with 13, 19 and 25 mm diameter Poplar wood with lengths varying from 8 to 65 mm long. Most of the experiments were conducted at 250°C for 60 min in a directly heated convective reactor with limited few in a fluidised bed reactor. Results showed increase in mass and energy yield with increasing particle length but opposite with particle diameter. © 2012 Canadian Society for Chemical Engineering     

Sanguinaria canadensis: Traditional Medicine,Phytochemical Composition,Biological Activities and Current Uses

Sanguinaria canadensis, also known as bloodroot, is a traditional medicine used by Native Americans to treat a diverse range of clinical conditions. The plants rhizome contains several alkaloids that individually target multiple molecular processes. These bioactive compounds, mechanistically correlate with the plant’s history of ethnobotanical use. Despite their identification over 50 years ago, the alkaloids of S. canadensis have not been developed into successful therapeutic agents. Instead, they have been associated with clinical toxicities ranging from mouthwash induced leukoplakia to cancer salve necrosis and treatment failure. This review explores the historical use of S. canadensis, the molecular actions of the benzophenanthridine and protopin alkaloids it contains, and explores natural alkaloid variation as a possible rationale for the inconsistent efficacy and toxicities encountered by S. canadensis therapies. Current veterinary and medicinal uses of the plant are studied with an assessment of obstacles to the pharmaceutical development of S. canadensis alkaloid based therapeutics.     

Vanadium(V)/mandelic acid initiated graft copolymerization of acrylamide onto guar gum in an aqueous medium

The graft copolymerization reaction of acrylamide onto guar gum with a vanadium(V)/mandelic acid redox pair was carried out in an N₂ atmosphere. The optimum concentrations of vanadium(V), mandelic acid, hydrogen ions, acrylamide, and guar gum for the maximum percentage of grafting were 6.0 × 10^?3, 2.0 × 10^?2, 55.0 × 10^?2, and 20.0 × 10^?2 mol/dm³ and 110.1 × 10^?2 g/dm³, respectively. The optimum time and temperature of reaction were 90 min and 35°C, respectively, and during the study of [H⁺] variation, a prompt change in the value of the grafting parameters was observed. The maximum percentage of swelling of the graft copolymer was achieved at room temperature in 1 h. Studies of the flocculation, viscosity, and metal‐ion absorption capacity were also performed. The synthesized graft copolymer was characterized by Fourier transform infrared spectroscopy and thermogravimetric analyses, which showed that the grafted guar gum was thermally more stable than the ungrafted guar gum. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

十字滑块联轴器工作效率及自锁理论的研究

通过对十字滑块联轴器的运动和力进行分析，推导出了十字滑块联轴器的瞬时效率及平均效率的理论公式，并探讨了自锁问题，为十字滑块联轴器应用提供了理论基础。     

Biosorption of mercury and lead by dried Aspergillus niger Tiegh. isolated from estuarine sediments

The sorption of Hg and Pb from mono‐metal and bi‐metal solution under different concentrations (20ppm–80ppm) was studied using dried Aspergillus niger biomass. The biosorption of Hg and Pb from the mono‐metal solution was found to be much better than from the bi‐metal solution. The maximum sorption of heavy metals was observed at pH 5–6 and at temperature 25°C–26°C. Biosorption of heavy metals from mono‐metal and bi‐metal solutions followed the Langmuir and Freundlich isotherm. The role of different functional groups like amine, hydroxyl, carboxyl and the phosphate group was confirmed by FTIR. The adsorption of metal ions on the biomass surface and the possible ion exchange mechanism was confirmed using SEM‐EDAX studies. A. niger can be used as a good biosorption agent for removing Hg and Pb from aqueous solution when present individually or in combination.     

Charge conduction and photogeneration process in hybrid materials of conjugated polymer and dye-sensitized TiO2 thin-film device

A thin-film hybrid structure consisting of dye-sensitized TiO₂ in combination with polypyrrole (PPy) is developed over indium tin oxide (ITO)-coated glass substrate. The steady-state photoconductivity and current–voltage (J–V) characteristics were recorded in the dark as well as under illumination for the fabricated device having the structure ITO/PPy/TY+TiO₂/Al. The current–voltage (J–V) characteristics of the device in the dark are explained by the formation of percolation networks of nano-particles between the electrodes. The device becomes symmetric at high voltage suggesting the electron injection from the electrodes into the conduction band of TiO₂ under both bias (reverse and forward) directions and the respective current is controled by charge carrier transport. Photoaction spectra of the device prove that the photogeneration of charge carriers is significantly enhanced and spectrally broadened only if electron transfer from the polymers to the dye is possible. It is also found that the increase in concentration of nano-particles changes the spectral shape of the hybrid structure as well as the photoresponse. These results show that a significant photoresponse can be achieved in hybrid materials of dye-sensitized TiO₂ nano-particles dispersed in conducting polymer.     

Elasto-plastic finite element analysis of a crack in an infinite plate

The elastic support method was recently developed to simulate the effects of unbounded solids in the finite element analysis of stresses and displacements. The method eliminates all the computational disadvantages encountered in the use of `infinite' elements or coupled finite element boundary element methods while retaining all the computational advantages of the finite element method. In this paper, the method is extended to the elasto-plastic analysis of fracture in infinite solids by using the load increment approach and including the effects of strain hardening. Numerical tests and parametric study are conducted by analysing a straight crack in an infinite plate. Present results for J integrals and plastified zones are compared, respectively, with analytical solutions and available results obtained by using the body force method. The agreement between the results is found to be very good even if the truncation boundary of the finite element model is located very close to the crack tip or the plastified zone.     

Development and in vitro evaluation of alginate gel-encapsulated, chitosan-coated ceramic nanocores for oral delivery of enzyme

The successful administration of protein and peptide drugs by oral route maintaining their active conformation remains a key challenge in the field of pharmaceutical technology. In the present study, we propose the use of a nanosize ceramic core-based system for effective oral delivery of acid-labile model enzyme, serratiopeptidase (STP). Ceramic core was prepared by colloidal precipitation and sonication of disodium hydrogen phosphate solution and calcium chloride solution at room temperature. The core was coated with chitosan under constant stirring and Fourier-Transform Infra Red Spectroscopy (FTIR) confirmed phosphoric groups of calcium phosphate linked with ammonium groups of chitosan in the nanoparticles; then the enzyme was adsorbed over the preformed nanocore. Protein-loaded nanocore was further encapsulated into alginate gel for enzyme protection. Prepared system was characterized for size, shape, loading efficiency, and in vitro release profile (pH 1.2 and pH 7.4). The effect of processing variables on the size of the core was evaluated to form small, uniform, and discrete nanocores. Stability and integrity of enzyme during processing steps was assessed by in vitro proteolytic activity. The prepared system was examined to be spherical in shape with diameter 925 ± 6.81 nm using TEM. The in vitro release data followed the Higuchi model, showing a low amount (26% ± 2.4%) of diffusion-controlled drug release (R² = 0.9429) in acidic buffer up to a period of 2 to 6 hours, signifying the integrity of alginate gel in acid. In the alkaline medium sustained and nearly complete first order release of protein was observed up to a 6 hours. It is inferred that the protein-loaded ceramic core acts as a reservoir of the adsorbed enzyme and alginate gel provides protection to STP for controlled release in intestinal pH when compared to the enzyme solution.     

Time exposure performance of Mo-Au Gibbsian segregating alloys for extreme ultraviolet collector optics

Successful implementation of extreme ultraviolet (EUV) lithography depends on research and progress toward minimizing collector optics degradation from intense plasma erosion and debris deposition. Thus studying the surface degradation process and implementing innovative methods, which could enhance the surface chemistry causing the mirrors to suffer less damage, is crucial for this technology development. A Mo-Au Gibbsian segregation (GS) alloy is deposited on Si using a dc dual-magnetron cosputtering system and the damage is investigated as a result of time dependent exposure in an EUV source. A thin Au segregating layer is maintained through segregation during exposure, even though overall erosion in the Mo-Au sample is taking place in the bulk. The reflective material, Mo, underneath the segregating layer is protected by this sacrificial layer, which is lost due to preferential sputtering. In addition to theoretical work, experimental results are presented on the effectiveness of the GS alloys to be used as potential EUV collector optics material.