Experimental investigation of wear modes of hardened rail material used in Australian heavy-haul railways

This work investigates the effects of contact pressure and geometry in rolling-contact wear tests by using discs with different radii of curvature to simulate the varying contact conditions that may be typically found in the field. The tests were conducted without any significant amount of traction, but micro slip was still observed due to contact deformation. Moreover, variation of contact pressure was observed due to contact patch elongation and diameter reduction. Rolling contact fatigue, adhesive and sliding wear were observed on the curved contact interface. The development of different wear regimes and material removal phenomena were analyzed using microscopic images in order to broaden the understanding of the wear mechanisms occurring in the rail-wheel contact.

Visible-light-induced click chemistry

A rapid and catalyst-free cycloaddition system for visible-light-induced click chemistry is reported. A readily accessible photoreactive 2H-azirine moiety was designed to absorb light at wavelengths above 400 nm. Irradiation with low-energy light sources thus enables efficient small-molecule synthesis with a diverse range of multiple-bond-containing compounds. Moreover, in order to demonstrate the efficiency of the current approach, quantitative ligation of the photoactivatable chromophore with functional polymeric substrates was performed and full conversion with irradiation times of only 1 min at ambient conditions was achieved. The current report thus presents a highly efficient method for applications involving selective cycloaddition to electron-deficient multiple-bond-containing materials.

Photochemical design of stimuli-responsive nanoparticles prepared by supramolecular host–guest chemistry

We introduce the design of a thermoresponsive nanoparticle via sacrificial micelle formation based on supramolecular host–guest chemistry. Reversible addition–fragmentation chain transfer (RAFT) polymerization was employed to synthesize well-defined polymer blocks of poly(N,N-dimethylacrylamide) (poly(DMAAm)) (Mn,SEC = 10 700 g mol–1, Đ = 1.3) and poly(N-isopropylacrylamide) (poly(NiPAAm)) (Mn,SEC = 39 700 g mol–1, Đ = 1.2), carrying supramolecular recognition units at the chain termini. Further, 2-methoxy-6-methylbenzaldehyde moieties (photoenols, PE) were statistically incorporated into the backbone of the poly(NiPAAm) block as photoactive cross-linking units. Host–guest interactions of adamantane (Ada) (at the terminus of the poly(NiPAAm/PE) chain) and β-cyclodextrin (CD) (attached to the poly(DMAAm chain end) result in a supramolecular diblock copolymer. In aqueous solution, the diblock copolymer undergoes micellization when heated above the lower critical solution temperature (LCST) of the thermoresponsive poly(NiPAAm/PE) chain, forming the core of the micelle. Via the addition of a 4-arm maleimide cross-linker and irradiation with UV light, the micelle is cross-linked in its core via the photoinduced Diels–Alder reaction of maleimide and PE units. The adamantyl–cyclodextrin linkage is subsequently cleaved by the destruction of the β-CD, affording narrowly distributed thermoresponsive nanoparticles with a trigger temperature close to 30 °C. Polymer chain analysis was performed via size exclusion chromatography (SEC), nuclear magnetic resonance (NMR) spectroscopy, and dynamic light scattering (DLS). The size and thermoresponsive behavior of the micelles and nanoparticles were investigated via DLS as well as atomic force microscopy (AFM).

A Chlamydia trachomatis strain with a chemically generated amino acid substitution (P370L) in the cthtrA gene shows reduced elementary body production

Background Chlamydia (C.) trachomatis is the most prevalent bacterial sexually transmitted infection worldwide and the leading cause of preventable blindness. Genetic approaches to investigate C. trachomatis have been only recently developed due to the organism’s intracellular developmental cycle. HtrA is a critical stress response serine protease and chaperone for many bacteria and in C. trachomatis has been previously shown to be important for heat stress and the replicative phase of development using a chemical inhibitor of the CtHtrA activity. In this study, chemically-induced SNVs in the cthtrA gene that resulted in amino acid substitutions (A240V, G475E, and P370L) were identified and characterized. Methods SNVs were initially biochemically characterized in vitro using recombinant protein techniques to confirm a functional impact on proteolysis. The C. trachomatis strains containing the SNVs with marked reductions in proteolysis were investigated in cell culture to identify phenotypes that could be linked to CtHtrA function. Results The strain harboring the SNV with the most marked impact on proteolysis (cthtrAP370L) was detected to have a significant reduction in the production of infectious elementary bodies. Conclusions This provides genetic evidence that CtHtrA is critical for the C. trachomatis developmental cycle.

Radon-222 activity flux measurement using activated charcoal canisters: Revisiting the methodology

The measurement of radon ((222)Rn) activity flux using activated charcoal canisters was examined to investigate the distribution of the adsorbed (222)Rn in the charcoal bed and the relationship between (222)Rn activity flux and exposure time. The activity flux of (222)Rn from five sources of varying strengths was measured for exposure times of one, two, three, five, seven, 10, and 14 days. The distribution of the adsorbed (222)Rn in the charcoal bed was obtained by dividing the bed into six layers and counting each layer separately after the exposure. (222)Rn activity decreased in the layers that were away from the exposed surface. Nevertheless, the results demonstrated that only a small correction might be required in the actual application of charcoal canisters for activity flux measurement, where calibration standards were often prepared by the uniform mixing of radium ((226)Ra) in the matrix. This was because the diffusion of (222)Rn in the charcoal bed and the detection efficiency as a function of the charcoal depth tended to counterbalance each other. The influence of exposure time on the measured (222)Rn activity flux was observed in two situations of the canister exposure layout: (a) canister sealed to an open bed of the material and (b) canister sealed over a jar containing the material. The measured (222)Rn activity flux decreased as the exposure time increased. The change in the former situation was significant with an exponential decrease as the exposure time increased. In the latter case, lesser reduction was noticed in the observed activity flux with respect to exposure time. This reduction might have been related to certain factors, such as absorption site saturation or the back diffusion of (222)Rn gas occurring at the canister-soil interface.

Inhibition of myeloperoxidase- and neutrophil-mediated oxidant production by tetraethyl and tetramethyl nitroxides

The powerful oxidant HOCl (hypochlorous acid and its corresponding anion, −OCl) generated by the myeloperoxidase (MPO)–H2O2–Cl− system of activated leukocytes is strongly associated with multiple human inflammatory diseases; consequently there is considerable interest in inhibition of this enzyme. Nitroxides are established antioxidants of low toxicity that can attenuate oxidation in animal models, with this ascribed to superoxide dismutase or radical-scavenging activities. We have shown (M.D. Rees et al., Biochem. J. 421, 79–86, 2009) that nitroxides, including 4-amino-TEMPO (4-amino-2,2,6,6-tetramethylpiperidin-1-yloxyl radical), are potent inhibitors of HOCl formation by isolated MPO and activated neutrophils, with IC50 values of ~1 and ~6 µM respectively. The utility of tetramethyl-substituted nitroxides is, however, limited by their rapid reduction by biological reductants. The corresponding tetraethyl-substituted nitroxides have, however, been reported to be less susceptible to reduction. In this study we show that the tetraethyl species were reduced less rapidly than the tetramethyl species by both human plasma (89–99% decreased rate of reduction) and activated human neutrophils (62–75% decreased rate). The tetraethyl-substituted nitroxides retained their ability to inhibit HOCl production by MPO and activated neutrophils with IC50 values in the low-micromolar range; in some cases inhibition was enhanced compared to tetramethyl substitution. Nitroxides with rigid structures (fused oxaspiro rings) were, however, inactive. Overall, these data indicate that tetraethyl-substituted nitroxides are potent inhibitors of oxidant formation by MPO, with longer plasma and cellular half-lives compared to the tetramethyl species, potentially allowing lower doses to be employed.

Development and characterisation of a new bioink for additive tissue manufacturing

Additive manufacturing forms a potential route towards economically viable production of cellular constructs for tissue engineering. Hydrogels are a suitable class of materials for cell delivery and 3D culture, but are generally unsuitable as construction materials. Gelatine-methacrylamide is an example of such a hydrogel system widely used in the field of tissue engineering, e.g. for cartilage and cardiovascular applications. Here we show that by the addition of gellan gum to gelatine-methacrylamide and tailoring salt concentrations, rheological properties such as pseudo-plasticity and yield stress can be optimised towards gel dispensing for additive manufacturing processes. In the hydrogel formulation, salt is partly substituted by mannose to obtain isotonicity and prevent a reduction in cell viability. With this, the potential of this new bioink for additive tissue manufacturing purposes is demonstrated.

Unimolecular reaction chemistry of a charge-tagged beta-hydroxyperoxyl radical

β-Hydroxyperoxyl radicals are formed during atmospheric oxidation of unsaturated volatile organic compounds such as isoprene. They are intermediates in the combustion of alcohols. In these environments the unimolecular isomerization and decomposition of β-hydroxyperoxyl radicals may be of importance, either through chemical or thermal activation. We have used ion-trap mass spectrometry to generate the distonic charge-tagged β-hydroxyalkyl radical anion, ˙CH2C(OH)(CH3)CH2C(O)O−, and investigated its subsequent reaction with O2 in the gas phase under conditions that are devoid of complicating radical–radical reactions. Quantum chemical calculations and master equation/RRKM theory modeling are used to rationalize the results and discern a reaction mechanism. Reaction is found to proceed via initial hydrogen abstraction from the γ-methylene group and from the β-hydroxyl group, with both reaction channels eventually forming isobaric product ions due to loss of either ˙OH + HCHO or ˙OH + CO2. Isotope labeling studies confirm that a 1,5-hydrogen shift from the β-hydroxyl functionality results in a hydroperoxyalkoxyl radical intermediate that can undergo further unimolecular dissociations. Furthermore, this study confirms that the facile decomposition of β-hydroxyperoxyl radicals can yield ˙OH in the gas phase.

Mortality reduction following the air pollution control measures during the 2010 Asian Games

Though increased particulate air pollution has been consistently associated with elevated mortality, evidence regarding whether diminished particulate air pollution would lead to mortality reduction is limited. Citywide air pollution mitigation program during the 2010 Asian Games in Guangzhou, China, provided such an opportunity. Daily mortality from non-accidental, cardiovascular and respiratory diseases was compared for 51 intervention days (November 1–December 21) in 2010 with the same calendar date of baseline years (2006–2009 and 2011). Relative risk (RR) and 95% confidence interval (95% CI) were estimated using a time series Poisson model, adjusting for day of week, public holidays, daily mean temperature and relative humidity. Daily PM10 (particle with aerodynamic diameter less than 10 μm) decreased from 88.64 μg/m3 during the baseline period to 80.61 μg/m3 during the Asian Games period. Other measured air pollutants and weather variables did not differ substantially. Daily mortality from non-accidental, cardiovascular and respiratory diseases decreased from 32, 11 and 6 during the baseline period to 25, 8 and 5 during the Games period, the corresponding RR for the Games period compared with the baseline period was 0.79 (95% CI: 0.73–0.86), 0.77 (95% CI: 0.66–0.89) and 0.68 (95% CI: 0.57–0.80), respectively. No significant decreases were observed in other months of 2010 in Guangzhou and intervention period in two control cities. This finding supports the efforts to reduce air pollution and improve public health through transportation restriction and industrial emission control.

Simultaneous kinetic spectrometric determination of three flavonoid antioxidants in fruit with the aid of chemometrics

A simple, inexpensive and sensitive kinetic spectrophotometric method was developed for the simultaneous determination of three anti-carcinogenic flavonoids: catechin, quercetin and naringenin, in fruit samples. A yellow chelate product was produced in the presence neocuproine and Cu(I) – a reduction product of the reaction between the flavonoids with Cu(II), and this enabled the quantitative measurements with UV–vis spectrophotometry. The overlapping spectra obtained, were resolved with chemometrics calibration models, and the best performing method was the fast independent component analysis (fast-ICA/PCR (Principal component regression)); the limits of detection were 0.075, 0.057 and 0.063 mg L−1 for catechin, quercetin and naringenin, respectively. The novel method was found to outperform significantly the common HPLC procedure.

Predicting tours and probabilistic simulation for BKZ lattice reduction algorithm

We investigate the terminating concept of BKZ reduction first introduced by Hanrot et al. [Crypto'11] and make extensive experiments to predict the number of tours necessary to obtain the best possible trade off between reduction time and quality. Then, we improve Buchmann and Lindner's result [Indocrypt'09] to find sub-lattice collision in SWIFFT. We illustrate that further improvement in time is possible through special setting of SWIFFT parameters and also through the combination of different reduction parameters adaptively. Our contribution also include a probabilistic simulation approach top-up deterministic simulation described by Chen and Nguyen [Asiacrypt'11] that can able to predict the Gram-Schmidt norms more accurately for large block sizes.

Performance analysis of solar desiccant-evaporative cooling for a commercial building under different Australian climates

This paper evaluates and compares the system performance of a solar desiccant-evaporative cooling (SDEC) system with a referenced conventional variable air volume (VAV) system for a typical office building in all 8 Australian capital cities. A simulation model of the building is developed using the whole building simulation software EnergyPlus. The performance indicators for the comparison are system coefficient of performance (COP), annual primary energy consumption, annual energy savings, and annual CO2 emissions reduction. The simulation results show that Darwin has the most apparent advantages for SDEC system applications with an annual energy savings of 557 GJ and CO2 emission reduction of 121 tonnes. The maximum system COP is 7. For other climate zones such as Canberra, Hobart and Melbourne, the SDEC system is not as energy efficient as the conventional VAV system.

Design a zero energy house in Brisbane, Australia

Due to the increasing energy demand and global warming effects, energy efficient buildings have become increasingly important in the modern construction industry. This research is conducted to evaluate the energy performance, financial feasibility and potential energy savings of zero energy houses. Through the use of building computer simulation technique, a 5 stars energy rated house was modelled and validated by comparing the energy performance of a base case scenario to a typical house in Brisbane. By integrating energy reduction strategies and utilizing onsite renewable energy such as solar energy, zero energy performance is achieved. It is found that approximately 66 % energy savings can be achieved in the household annual energy usage by focusing on maximizing the thermal performance of building envelope, minimizing the energy requirements and incorporating solar energy technologies.

Dioxin risk reduction programme at the most severe dioxin hot spot in Vietnam: Residual knowledge, attitude and practices five years post intervention

Bien Hoa Airbase was one of the bulk storage and supply facilities for defoliants during the Vietnam War. Environmental and biological samples taken around the airbase have elevated levels of dioxin. In 2007, a pre-intervention knowledge, attitude and practice (KAP) survey of local residents living in Trung Dung and Tan Phong wards was undertaken regarding appropriate strategies to reduce dioxin exposure. A risk reduction programme was implemented in 2008 and post-intervention KAP surveys were undertaken in 2009 and 2013 to evaluate the longer term impacts. Quantitative assessment was undertaken via a KAP survey in 2013 among 600 local residents randomly selected from the two intervention wards and one control ward (Buu Long). Eight in-depth interviews and two focus group discussions were also undertaken for qualitative assessment. Most programme activities had ceased and dioxin risk communication activities had not been integrated into local routine health education programmes; however, main results generally remained and were better than that in Buu Long. In total, 48.2% of households undertook measures to prevent exposure, higher than those in pre- and post-intervention surveys (25.8% and 39.7%) and the control ward (7.7%). Migration and the sensitive nature of dioxin issues were the main challenges for the programme's sustainability

Pumping systems: Design and energy efficiency

Pumping systems are widely used in many applications, including municipal water/wastewater services, domestic, commercial and agricultural services, and industrial processes. They are a very significant energy user and consume nearly 20% of the world’s electrical energy demand. Therefore, improving the energy efficiency of pumping systems can provide great benefits in terms of energy, environment, and cost reduction. In this entry, an overview of pump classification with pros and cons of each type of pump is presented. The procedures used to design pumping systems are also outlined. This is then followed by a discussion on the opportunities for improving the energy efficiency of pumping systems during every stage of design, selection, operation, and maintenance.