Antioxidant Protective Effect of Glibenclamide and Metformin in Combination with Honey in Pancreas of Streptozotocin-Induced Diabetic Rats

Hyperglycemia exerts toxic effects on the pancreatic β-cells. This study investigated the hypothesis that the common antidiabetic drugs glibenclamide and metformin, in combination with tualang honey, offer additional protection for the pancreas of streptozotocin (STZ)-induced diabetic rats against oxidative stress and damage. Diabetes was induced in male Sprague Dawley rats by a single dose of STZ (60 mg/kg; ip). Diabetic rats had significantly elevated levels of lipid peroxidation (TBARS), up-regulated activities of superoxide dismutase (SOD) and glutathione peroxidase (GPx) while catalase (CAT) activity was significantly reduced. Glibenclamide and metformin produced no significant effects on TBARS and antioxidant enzymes except GPx in diabetic rats. In contrast, the combination of glibenclamide, metformin and honey significantly up-regulated CAT activity and down-regulated GPx activity while TBARS levels were significantly reduced. These findings suggest that tualang honey potentiates the effect of glibenclamide and metformin to protect diabetic rat pancreas against oxidative stress and damage.     

The influence of self-field effects on the temperature dependence of the Josephson supercurrent

The temperature dependence of the Josephson supercurrent has been measured in a number of blob junctions formed between Nb-Zr wire and Pb-Sn solder. In favorable cases the critical current is found to increase periodically with decreasing temperature. The effect is due to the self-field generated by current flow in an asymmetric double junction. Interchanging the current and voltage leads alters the geometry of such a junction and hence alters the periodicity.     

Incorporation of thermally labile additives in polyimide carbon membrane for hydrogen separation

In this study, three thermally labile additives microcrystalline cellulose (MCC), nanocrystalline cellulose (NCC), and polyvinylpyrrolidone (PVP) were introduced to the P84-copolyimide (PI) solution. PI-based carbon tubular membranes were fabricated using dip-coating method, followed by sample characterizations in order to determine their structural morphologies, thermal stability and gas permeation performance. NCC was added as the membrane pore former for the hydrogen gas (H₂) separation. While tests involving pure H₂ and N₂ permeation were carried out at room temperature, carbon membranes were carbonized at a final temperature of 800 °C, with the heating rate of 3 °C/min under the Ar flow. Excellent result of H₂/N₂ selectivity was obtained with value of 430.06 ± 4.16. Addition of NCC has significantly increased the number of pore channels in the membrane, hence, contributing to high gas permeance and selectivity. NCC has shown potential as a good additive for an enhanced hydrogen separation performance.     

An improved hybrid nanocomposites of rice husk derived graphene (GRHA)/Zeolitic imidazolate framework-8 for hydrogen adsorption

In this work, hybrid nanocomposites rice husk derived graphene (GRHA) and zeolitic imidazolate framework-8 (ZIF-8) were prepared for hydrogen adsorption. The main contribution of this study is the simplification of the synthesized GRHA/ZIF-8 hybrid nanocomposites. Besides that, the use of synthesized graphene from rice husk (RH) could help in overcoming environmental issue since disposal of RH is rather challenging. GRHA was obtained through calcining rice husk ash (RHA) at 900 °C for 2 h in a muffle furnace at atmospheric condition while the nanocomposite of GRHA/ZIF-8 was produced in free solvent condition using deionized water at room temperature for only 1 h. The N₂ adsorption-desorption indicated a type I isotherm. Interestingly, it was found that the BET specific surface area (BET_SSA) of GRHA/ZIF-8 showed enhancement up to 3 times higher as compared to pristine GRHA with the addition of 0.2 g of GRHA. From the experimental data, the adsorption of H₂ by nanocomposite GRHA/ZIF-8 obeyed the pseudo-second order kinetic model and intraparticle diffusion model with R² value up to 0.9890 and 0.8087 respectively at 12 bar. Moreover, the GRHA/ZIF-8 possessed highest hydrogen adsorption of 31.84 mmol/g at 12 bar. These impressive results are justified by the combination of ZIF-8's microporosity and GRHA's mesoporosity.     

Simulation and experimental investigation of a wide band PZ MEMS harvester at low frequencies

A commercial brass reinforced PZ bimorph cantilever of the type 5H4E was simulated using COMSOL FEM software and then a serious of experimental tests were carried out in a vibration laboratory using a labview of NI make as instrumentation and control system. By using a shaker the cantilever was vibrated and set into acceleration of 0.25?g?rms during all stages as this value was considered to be available and acceptable in balanced large rotating machines in industry. Field vibration spectrum analysis was carried out in a power station confirmed that. A band of frequencies ranging from 30 to 109?Hz was experimentally tested by using different perforated steel shims as a proof mass at the end of the cantilever. Values of 63?μW/cm³ at a frequency of 33?Hz for power density, 187?μW for max power, 14.8?V for max OCV, and 8.26?V for max, on load voltage, were obtained. Frequency resolution of 1?Hz was experienced. Trends of the results obtained experimentally and through simulation were comparable.     

Chemical Compositions, Antioxidant and Antimicrobial Activities of Essential Oils of Piper caninum Blume

Chemical composition, antioxidant and antimicrobial activities of the fresh leaves and stems oils of Piper caninum were investigated. A total of forty eight constituents were identified in the leaves (77.9%) and stems (87.0%) oil which were characterized by high proportions of phenylpropanoid, safrole with 17.1% for leaves and 25.5% for stems oil. Antioxidant activities were evaluated by using β-carotene/linoleic acid bleaching, DPPH radical scavenging and total phenolic content. Stems oil showed the highest inhibitory activity towards lipid peroxidation (114.9 ± 0.9%), compared to BHT (95.5 ± 0.5%), while leaves oil showed significant total phenolic content (27.4 ± 0.5 mg GA/g) equivalent to gallic acid. However, the essential oils showed weak activity towards DPPH free-radical scavenging. Evaluation of antimicrobial activity revealed that both oils exhibited strong activity against all bacteria strains with MIC values in the range 62.5 to 250 μg/mL, but weak activity against fungal strains. These findings suggest that the essential oils can be used as antioxidant and antimicrobial agents for therapeutic, nutraceutical industries and food manufactures.     

Enhancing Security in Mobile IPv6

In the Mobile IPv6 (MIPv6) protocol, a mobile node (MN) is a mobile device with a permanent home address (HoA) on its home link. The MN will acquire a care‐of address (CoA) when it roams into a foreign link. It then sends a binding update (BU) message to the home agent (HA) and the correspondent node (CN) to inform them of its current CoA so that future data packets destined for its HoA will be forwarded to the CoA. The BU message, however, is vulnerable to different types of security attacks, such as the man‐in‐the‐middle attack, the session hijacking attack, and the denial‐of‐service attack. The current security protocols in MIPv6 are not able to effectively protect the BU message against these attacks. The private‐key‐based BU (PKBU) protocol is proposed in this research to overcome the shortcomings of some existing MIPv6 protocols. PKBU incorporates a method to assert the address ownership of the MN, thus allowing the CN to validate that the MN is not a malicious node. The results obtained show that it addresses the security requirements while being able to check the address ownership of the MN. PKBU also incorporates a method to verify the reachability of the MN.     

Carbon tubular membranes from nanocrystalline cellulose blended with P84 co-polyimide for H2 and He separation

In this study, carbon tubular membranes were produced by employing P84 co-polyimide as a precursor material and nanocrystalline cellulose (NCC) as an additive. The synthesized NCC which was derived from recycled newspaper was used as a pore forming agent for the membrane. Various carbonization temperatures (600, 700, 800, and 900 °C) were used while the stabilization temperature was kept at 300 °C. The measurements of pure gases' (He, H₂, and N₂) permeance through all carbon tubular membranes produced were carried out at feed pressure of 8 bars. The results showed that higher carbonization temperatures resulted in more selective but less productive carbon membranes. The outcome of this study suggested that carbon tubular membrane fabricated from NCC blending with P84 co-polyimide as a promising candidate for H₂ and He recovery application with H₂/N₂ and He/N₂ selectivity of 434.68 ± 1.39 and 463.86 ± 8.12, respectively.