Determination of l-dopa using electropolymerized 3,3′,3″,3‴-tetraaminophthalocyanatonickel(II) film on glassy carbon electrode

Electropolymerized film of 3,3′,3″,3‴-tetraaminophthalocyanatonickel(II) (p-NiIITAPc) on glassy carbon (GC) electrode was used for the selective and stable determination of 3,4-dihydroxy-l-phenylalanine (l-dopa) in acetate buffer (pH 4.0) solution. Bare GC electrode fails to determine the concentration of l-dopa accurately in acetate buffer solution due to the cyclization reaction of dopaquinone to cyclodopa in solution. On the other hand, p-NiIITAPc electrode successfully determines the concentration of l-dopa accurately because the cyclization reaction was prevented at this electrode. It was found that the electrochemical reaction of l-dopa at the modified electrode is faster than that at the bare GC electrode. This was confirmed from the higher heterogeneous electron transfer rate constant (k0) of l-dopa at p-NiIITAPc electrode (3.35 × 10−2 cm s−1) when compared to that at the bare GC electrode (5.18 × 10−3 cm s−1). Further, it was found that p-NiIITAPc electrode separates the signals of ascorbic acid (AA) and l-dopa in a mixture with a peak separation of 220 mV. Lowest detection limit of 100 nM was achieved at the modified electrode using amperometric method. Common physiological interferents like uric acid, glucose and urea does not show any interference within the potential window of l-dopa oxidation. The present electrode system was also successfully applied to estimate the concentration of l-dopa in the commercially available tablets.

High performance all-carbon thin film supercapacitors

We fabricated high performance supercapacitors by using all carbon electrodes, with volume energy in the order of 10−3 Whcm−3, comparable to Li-ion batteries, and power densities in the range of 10 Wcm−3, better than laser-scribed-graphene supercapacitors. All-carbon supercapacitor electrodes are made by solution processing and filtering electrochemically-exfoliated graphene sheets mixed with clusters of spontaneously entangled multiwall carbon nanotubes. We maximize the capacitance by using a 1:1 weight ratio of graphene to multi-wall carbon nanotubes and by controlling their packing in the electrode film so as to maximize accessible surface and further enhance the charge collection. This electrode is transferred onto a plastic-paper-supported double-wall carbon nanotube film used as current collector. These all-carbon thin films are combined with plastic paper and gelled electrolyte to produce solid-state bendable thin film supercapacitors. We assembled supercapacitor cells in series in a planar configuration to increase the operating voltage and find that the shape of our supercapacitor film strongly affects its capacitance. An in-line superposition of rectangular sheets is superior to a cross superposition in maintaining high capacitance when subject to fast charge/discharge cycles. The effect is explained by addressing the mechanism of ion diffusion into stacked graphene sheets.

Durability performance of carbon fibre-reinforced polymer strengthened circular hollow steel members under cold weather

The use of circular hollow steel members has attracted a great deal of attention during past few years because of having excellent structural properties, aesthetic appearance, corrosion and fire protection capability. However, no one can deny the structural deficiency of such structures due to reduction of strength when they are exposed to severe environmental conditions such as marine environment, cold and hot weather. Hence strengthening and retrofitting of structural steel members is now very imperative. This paper presents the findings of a research program that was conducted to study the bond durability of carbon fibre-reinforced polymer (CFRP) strengthened steel tubular members under cold weather and tested under four-point bending. Six number of CFRP-strengthened specimens and one unstrengthened specimen were considered in this program. The three specimens having sand blasted surface to be strengthened was pre-treated with MBrace primer and other three were remained untreated and then cured under ambient temperature at least four weeks and cold weather (3 C) for three and six months period of time. Quasi-static tests were then performed on beams to failure under four-point bending. The structural response of each specimen was predicted in terms of failure load, mid-span deflection, composite beam behaviour and failure mode. The research outcomes show that the cold weather immersion had an adverse effect on durability of CFRP-strengthened steel structures. Moreover, the epoxy based adhesion promoter was found to enhance the bond durability in plastic range. The analytical models presented in this study were found to be in good agreement in terms of predicting ultimate load and deflection. Finally, design factors are proposed to address the short-terms durability performance under cold weather.

Formation of carbon nanoscrolls from graphene nanoribbons : a molecular dynamics study

Carbon nanoscrolls (CNSs) are one of the carbon-based nanomaterials similar to carbon nanotubes (CNTs) but are not widely studied in spite of their great potential applications. Their practical applications are hindered by the challenging fabrication of the CNSs. A physical approach has been proposed recently to fabricate the CNS by rolling up a monolayer graphene nanoribbon (GNR) around a CNT driven by the interaction energy between them. In this study, we perform extensive molecular dynamics (MD) simulations to investigate the various factors that impact the formation of the CNS from GNR. Our simulation results show that the formation of the CNS is sensitive to the length of the CNT and temperature. When the GNR is functionalized with hydrogen, the formation of the CNS is determined by the density and distribution of the hydrogen atoms. Graphyne, the allotrope of graphene, is inferior to graphene in the formation of the CNS due to the weaker bonds and the associated smaller atom density. The mechanism behind the rolling of GNR into CNS lies in the balance between the GNR–CNT van der Waals (vdW) interactions and the strain energy of GNR. The present work reveals new important insights and provides useful guidelines for the fabrication of the CNS.

The darker side of green : plantation forestry and carbon violence in Uganda

In recent years, there has been a significant trend toward land acquisition in developing countries, establishing forestry plantations for offsetting carbon pollution generated in the Global North. Badged as “green economic development,” global carbon markets are often championed not only as solutions to climate change, but as drivers of positive development outcomes for local communities. But there is mounting evidence that these corporate land acquisitions for climate change mitigation—including forestry plantations—severely compromise not only local ecologies but also the livelihoods of the some of the world’s most vulnerable people living at subsistence level in rural areas in developing countries.

Wing morphology, echolocation calls, diet and emergence time of black-bearded tomb bats (Taphozous melanopogon, Emballonuridae) from southwest China

We studied the wing morphology, echolocation calls, diet and emergence time of the black-bearded tomb bat (Taphozous melanopogon) from May to October 2006 in Guangxi Province, southwest China. Taphozous melanopogon has wings with high aspect ratio, high loading and pointed wing-tip shape-characteristics associated with fast flight in open space. This species usually produces low-intensity, low frequency, and frequency-modulated (FM) calls usually containing up to four harmonics, with most energy in the second (or sometimes third) harmonic. The diet of this species consists mostly of Lepidoptera and Hemiptera. Timing of evening emergence is correlated with the time of sunset. This is the first study to describe the flight and echolocation behavior of this species in China, and opens the way for future studies of its biology.

Finite element modeling of carbon fibre reinforced polymer (CFRP) strengthened steel tubes under axial impact

Steel hollow sections used in structures such as bridges, buildings and space structures involve different strengthening techniques according to their structural purpose and shape of the structural member. One such technique is external bonding of CFRP sheets to steel tubes. The performance of CFRP strengthening for steel structures has been proven under static loading while limited studies have been conducted on their behaviour under impact loading. In this study, a comprehensive numerical investigation is carried out to evaluate the response of CFRP strengthened steel tubes under dynamic axial impact loading. Impact force, axial deformation impact velocities are studied. The results of the numerical investigations are validated by experimental results. Based on the developed finite element (FE) model several output parameters are discussed. The results show that CFRP wrapping is an effective strengthening technique to increase the axial dynamic load bearing capacity by increasing the stiffness of the steel tube.

Risk factors for oesophageal, lung, oral and laryngeal cancers in black South Africans

The authors used data collected from 1995 to 1999, from an on-going cancer case–control study in greater Johannesburg, to estimate the importance of tobacco and alcohol consumption and other suspected risk factors with respect to cancer of the oesophagus (267 men and 138 women), lung (105 men and 41 women), oral cavity (87 men and 37 women), and larynx (51 men). Cancers not associated with tobacco or alcohol consumption were used as controls (804 men and 1370 women). Tobacco smoking was found to be the major risk factor for all of these cancers with odds ratios ranging from 2.6 (95% CI 1.5–4.5) for oesophageal cancer in female ex-smokers to 50.9 (95% CI 12.6–204.6) for lung cancer in women, and 23.9 (95% CI 9.5–60.3) for lung cancer and 23.6 (95% CI 4.6–121.2) for laryngeal cancer in men who smoked 15 or more grams of tobacco a day. This is the first time an association between smoking and oral and laryngeal cancers has been shown in sub-Saharan Africa. Long-term residence in the Transkei region in the southeast of the country continues to be a risk factor for oesophageal cancer, especially in women (odds ratio=14.7, 95% CI 4.7–46.0), possibly due to nutritional factors. There was a slight increase in lung cancer (odds ratio=2.9, 95% CI 1.1–7.5) in men working in ‘potentially noxious’ industries. ‘Frequent’ alcohol consumption, on its own, caused a marginally elevated risk for oesophageal cancer (odds ratio=1.7, 95% CI 1.0–2.9, for women and odds ratio=1.8, 95% CI 1.2–2.8, for men). The risks for oesophageal cancer in relation to alcohol consumption increased significantly in male and female smokers (odds ratio=4.7, 95% CI=2.8–7.9 in males and odds ratio=4.8, 95% CI 3.2–6.1 in females). The above results are broadly in line with international findings.

Antibodies against human herpesvirus 8 in black South African patients with cancer

Background Infection with human herpesvirus 8 (HHV-8) has been consistently linked to Kaposi's sarcoma, but its mode of transmission, association with other cancers, and interaction with the human immunodeficiency virus type 1 (HIV-1) are largely unknown. Methods Between January 1992 and December 1997, we interviewed 3591 black patients with cancer in Johannesburg and Soweto, South Africa. Blood was tested for antibodies against HIV-1 and HHV-8 in 3344 of the patients. Antibodies against HHV-8 were detected with an indirect immunofluorescence assay. The intensity of the fluorescent signal correlated well with the titers of antibodies (P<0.001). The relations among the presence of anti–HHV-8 antibodies, sociodemographic and behavioral factors, type of cancer, and the presence or absence of coexistent HIV-1 infection were examined with the use of unconditional logistic-regression models. Results Among the 3293 subjects with cancers other than Kaposi's sarcoma, the standardized seroprevalence of antibodies against HHV-8 was 32 percent, which did not differ significantly from the standardized seroprevalence among black blood donors. Among these 3293 patients, the prevalence of antibodies against HHV-8 increased with increasing age (P<0.001) and an increasing number of sexual partners (P=0.05) and decreased with increasing years of education (P=0.007); it was not strongly associated with HIV-1 infection. Anti–HHV-8 antibodies were more frequent among black than white blood donors (P<0.001). Among the 51 patients with Kaposi's sarcoma, the standardized seroprevalence of antibodies against HHV-8 was 83 percent, significantly higher than the prevalence among those without Kaposi's sarcoma (P<0.001). For 16 other specific types of cancer, including multiple myeloma (108 cases) and prostate cancer (202 cases), the variation in the standardized seroprevalence of antibodies against HHV-8 was not remarkable. At a given intensity of fluorescence of anti–HHV-8 antibodies, Kaposi's sarcoma was more frequent among HIV-1–positive patients than among those who were HIV-1–negative (P<0.001). Conclusions Among black patients with cancer in South Africa, the seroprevalence of anti–HHV-8 antibodies is high and is specifically associated with Kaposi's sarcoma, particularly at high titers.

Experimental Study of crack propagation in carbon steel using acoustic emission

Acoustic emission technique has become a significant and powerful structural health monitoring tool for structures. Researches to date have been done on crack location, fatigue crack propagation in materials and severity assessment of failure using acoustic emission technique. Determining severity of failure in steel structures using acoustic emission technique is still a challenge to accurately determine the relationship between the severity of crack propagation and acoustic emission activities. In this study three point bending test on low carbon steel samples along with acoustic emission technique have been used to determine crack propagation and severity. A notch is introduced at the tension face of the loading point to the samples to initiate the crack. The results show that the percentage of load drop of the steel specimen has a reciprocal relationship with the crack opening i.e. crack opening zones are influenced by the loading rate. In post yielding region, common acoustic emission signal parameters such as, signal strength, energy and amplitudes are found to be higher than those at pre-yielding and at yielding.

Electropolymerisation of catalytically active PEDOT from an ionic liquid on a flexible carbon cloth using a sandwich cell configuration

We report the electropolymerization of poly(3,4-ethylenedioxythiopene) (PEDOT) from an ionic liquid, butyl-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide (C4mpyrTFSI) onto flexible carbon cloth electrodes. A continuous, homogeneous and well adhered coating of the individual cloth fibres is achieved by employing a sandwich cell arrangement where the carbon cloth which is soaked with electrolyte is placed between two indium tin oxide electrodes isolated from each other by a battery separator. The resultant PEDOT modified carbon cloth electrode demonstrates excellent activity for the oxygen reduction reaction which is due to the doping level, conductivity and morphology of the PEDOT layer and is also tolerant to the presence of methanol in the electrolyte. This simple approach therefore offers a route to fabricate flexible polymer electrodes that could be used in various electronic applications.

Investigating the link between carbon dioxide emissions and transport-related social exclusion in rural Northern Ireland

Carbon dioxide (CO2) is considered the most harmful of the greenhouse gases. Despite policy efforts, transport is the only sector experiencing an increase in the level of CO2 emissions and thereby possesses a major threat to sustainable development. In contrast, a reduced level of mobility has been associated with an increasing risk of being socially excluded. However, despite being the two key elements in transport policy, little effort has so far been made to investigate the links between CO2 emissions and social exclusion. This research contributes to this gap by analysing data from 157 weekly activity-travel diaries collected in rural Northern Ireland. CO2 emission levels were calculated using average speed models for different modes of transport. Regression analyses were then conducted to identify the socio-spatial patterns associated with these CO2 emissions, mode choice behaviour, and patterns of participation in activities. This research found that despite emitting a higher level of carbon dioxide, groups in rural areas possess the risk of being socially excluded due to their higher levels of mobility.

Black comedy : the ABC makes bold foray into race relations

ABC’s new Indigenous sketch show Black Comedy, which premiered last night, is touted as a “show by blackfellas … for everyone”. As a blackfella, I’m not sure I agree that it is for “everyone” but that’s precisely why I love it. It’s been over 40 years since Basically Black, the first Indigenous sketch show aired on our screens, and it’s been too long a wait to see our mob doing humour our way in our living rooms once again. The characters we met last night were, as promised, bigger and blacker than ever. When it comes to Australian television … well it’s about time.