Electro-osmotic dewatering of soaked hemp stems

ABSTRACT

Hemp stems were immersed in water as a pretreatment to enhance the production of hemp fiber. To reduce the high moisture content, the soaked hemp stems were dewatered using a bench-type electro-osmotic roller press. Variables like applied voltage (12, 24, and 36?V), roller pressure (1000, 2000, and 3000?kPa), and duration of soaking of hemp stems (12, 24, and 36?h) were subjected to investigation and the percentage of total water expelled due to electro-osmotic dewatering (EOD) at various levels of experiments was recorded. Hemp stems soaked for 24?h treated at a roller pressure of 2,000?kPa at an applied voltage of 36?V showed the maximum water removal after EOD process. The water removal was found to be increasing with increase in applied voltage and roller pressure. Soaking time up to 32?h leads to an increase in water removal and then it started decreasing. The probable reason for that was the penetration of surface water into micropores and its adhesion to the lignocellulosic bonds. Electro-osmotic permeability of hemp stems at various levels of voltages, roller pressures, and soaking times was studied and the result proved that electro-osmotic permeability was inversely proportional to applied voltage and it was independent of the applied pressure.     

Effect of carbon black on the mechanical and dielectric properties of rubber ferrite composites containing barium ferrite

Fine particles of barium ferrite (BaFe₁₂O₁₉) were synthesized by the conventional ceramic technique. These materials were then characterized by the X‐ray diffraction method and incorporated in the natural rubber matrix according to a specific receipe for various loadings of ferrite. The rubber ferrite composites (RFC) thus obtained have several applications, and have the advantage of molding into complex shapes. For applications such as microwave absorbers, these composites should have an appropriate dielectric strength with the required mechanical and magnetic properties. The N330 (HAF) carbon black has been added to these RFCs for various loadings to modify the dielectric and mechanical properties. In this article we report the effect of carbon black on the mechanical and dielectric properties of these RFCs. Both the mechanical and dielectric properties can be enhanced by the addition of an appropriate amount of carbon black. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 769–778, 2003     

Generalized confidence intervals for process capability indices

The concept of generalized confidence intervals is used to derive lower confidence limits for some of the commonly used process capability indices. For the cases where approximate lower confidence limits are already available, numerical comparisons are made among the available approximations and the generalized lower confidence limit. The numerical results indicate that the generalized confidence interval does provide coverage probabilities very close to the nominal confidence level. Two examples are given to illustrate the results. Copyright © 2006 John Wiley & Sons, Ltd.     

Control of Switching Modes and Conductance Quantization in Oxygen Engineered HfOx based Memristive Devices

Hafnium oxide (HfO_x)‐based memristive devices have tremendous potential as nonvolatile resistive random access memory (RRAM) and in neuromorphic electronics. Despite its seemingly simple two‐terminal structure, a myriad of RRAM devices reported in the rapidly growing literature exhibit rather complex resistive switching behaviors. Using Pt/HfO_x/TiN‐based metal–insulator–metal structures as model systems, it is shown that a well‐controlled oxygen stoichiometry governs the filament formation and the occurrence of multiple switching modes. The oxygen vacancy concentration is found to be the key factor in manipulating the balance between electric field and Joule heating during formation, rupture (reset), and reformation (set) of the conductive filaments in the dielectric. In addition, the engineering of oxygen vacancies stabilizes atomic size filament constrictions exhibiting integer and half‐integer conductance quantization at room temperature during set and reset. Identifying the materials conditions of different switching modes and conductance quantization contributes to a unified switching model correlating structural and functional properties of RRAM materials. The possibility to engineer the oxygen stoichiometry in HfO_x will allow creating quantum point contacts with multiple conductance quanta as a first step toward multilevel memristive quantum devices.     

Effect of ball size on milling efficiency of zinc oxide dispersions

Zinc oxide (ZnO) was wet milled using inert Al₂O₃-ceramic balls having different diameter at different milling intervals and the milling efficiency of the resultant dispersion was followed through particle size analysis and zeta potential measurements. The results indicated that small-sized balls improved the milling efficiency. The highest share (%) of lower-size particles was obtained after 24?h of ball milling.     

Toxicological impact of TiO2 nanoparticles on Eudrilus euginiae

The concern regarding the toxicological effects of nanoparticles (NPs) on the terrestrial environment is increasing. To avoid risks of exposure to these NPs in the environment, it is essential to develop an understanding of their reactivity, toxicity, and persistency. Due to the increased usage of nano‐titanium dioxide (TiO₂) in various industrial products, an exponential increase in exposure is expected, which would exacerbate concerns about its ecological risks. The present study is conducted to evaluate the size‐dependent effects of TiO₂ NPs on the soil, especially on earthworm (Eudrilus euginiae). To date, many studies have been reported on the impact of TiO₂ NPs on ecotoxicology. However, histotoxicology studies are sparse. This study serves to be the first report on the size‐dependent histotoxicological impact of nano‐TiO₂ on earthworms particularly, E. euginiae. This report presents an intensive overall view of the longer time ecotoxicological impact of TiO₂ nanomaterials on various biological parameters of earthworms at cellular levels. The results show that the survival and growth of adult earthworms are severely affected by the TiO₂ NPs in the soil, which substantiates the adverse effects of TiO₂ NPs on earthworms.Inspec keywords: nanobiotechnology, nanoparticles, titanium compounds, semiconductor materials, toxicology, zoology, soil, cellular biophysics, particle sizeOther keywords: toxicological impact, nanoparticles, Eudrilus euginiae, terrestrial environment, soil, earthworm, ecotoxicology, size‐dependent histotoxicological impact, nanomaterials, biological parameters, cellular levels, TiO₂      

Barium Rare-Earth Hafnates: Synthesis, Characterization, and Potential Use as Substrates for YBa2Cu3O7-delta Superconductor

A new group of complex perovskites Ba₂REHfO_5.5 (where RE = La, Pr, Nd, and Eu) has been synthesized and sintered as single-phase materials with high sintered density and stability using a solid-state reaction method for the first time. The structure of Ba₂REHfO_5.5 has been studied by X-ray diffactometry (XRD) and all of the perovskites are isostructural and have a cubic structure. The dielectric constant and loss factor values of these materials are in a range suitable for their use as substrates for YBa₂Cu₃O_7-delta superconductors. XRD and resistivity measurements show that there is no detectable reaction between YBa₂Cu₃O_7-delta and Ba₂REHfO_5.5, even when the two substances are mixed thoroughly and sintered at 950°C for 15 h. The addition of Ba₂REHfO_5.5 up to 20 vol% in YBa₂Cu₃O_7-delta-Ba₂REHfO_5.5 composite shows no detrimental effect on the superconducting transition temperature of YBa₂Cu₃O_7-delta. Thick films of YBa₂Cu₃O_7-delta fabricated on polycrystalline Ba₂REHfO_5.5 substrate have a superconducting zero resistivity transition of 92 K, indicating the suitability of these new materials as substrates for YBa₂Cu₃O_7-delta films.     

Effect of vulcanization systems and antioxidants on discoloration and degradation of natural rubber latex thread under UV radiation

The effect of accelerator combinations and antioxidants on UV radiation degradation of natural rubber (NR) latex thread with a conventional and efficient vulcanization system is presented. Zinc diethyl dithiocarbamate (ZDEC), zinc dibutyl dithiocarbamate (ZDBC), zinc mercaptobenzothiazole (ZMBT), and tetramethyl thiuram disulfide (TMTD) were used as accelerators. The antioxidants used were reaction products of butylated p‐cresol and dicyclopentadiene (Wingstay‐L), Tris‐nonylated phenyl phosphite (Crystol EPR 3400), styrenated phenol (SP), and polymerized 1,2‐dihydro 2,2,4‐trimethyl quinoline (HS). The thread samples were exposed to UV radiation and the appearance and physical properties of the thread were examined. The results indicated that the threads having ZDBC + ZDEC and ZDBC + ZMBT combinations as accelerators are more resistant to UV radiation than the thread having the ZDEC + ZMBT combination. The antioxidants Wingstay‐L and SP + HS are effective in retaining the physical properties of the thread after UV exposure, and Crystol EPR 3400 is better in reducing discoloration. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 304–310, 2000     

Single-ion conducting polymer-silicate nanocomposite electrolytes for lithium battery applications

Solid-state polymer-silicate nanocomposite electrolytes based on an amorphous polymer poly[(oxyethylene)₈ methacrylate], POEM, and lithium montmorillonite clay were fabricated and characterized to investigate the feasibility of their use as ‘salt-free’ electrolytes in lithium polymer batteries. X-ray scattering and transmission electron microscopy studies indicate the formation of an intercalated morphology in the nanocomposites due to favorable interactions between the polymer matrix and the clay. The morphology of the nanocomposite is intricately linked to the amount of silicate in the system. At low clay contents, dynamic rheological testing verifies that silicate incorporation enhances the mechanical properties of POEM, while impedance spectroscopy shows an improvement in electrical properties. With clay content ≥15 wt.%, mechanical properties are further improved but the formation of an apparent superlattice structure correlates with a loss in the electrical properties of the nanocomposite. The use of suitably modified clays in nanocomposites with high clay contents eliminates this superstructure formation, yielding materials with enhanced performance.     

Antibacterial activity of ciprofloxacin-beta-cyclodextrin complex and its efficacy in dental implants

Ciprofloxacin forms an inclusion complex with beta-cyclodextrin. The in vitro antibacterial activity of ciprofloxacin on E. coli and Staphylococcus aureus was found better on complexation. The complex was found very effective as a local antibacterial agent when used in dental implants. Significant reduction in the gingival index, probing pocket depth and microbial growth coupled with gain in attachment at the test site compared to control on the 14th day was observed when the implants containing 2.0 mg of the complex equivalent to 0.4 mg of ciprofloxacin was used in clinical trials.