Effect of pretreatment on saccharification of sugarcane bagasse by complex and simple enzyme mixtures

Saccharification of sugarcane bagasse pretreated at the pilot-scale with different processes (in combination with steam-explosion) was evaluated. Maximum glucan conversion with Celluclast 1.5 L (15–25 FPU/g glucan) was in the following order: glycerol/HCl > HCl > H2SO4 > NaOH, with the glycerol system achieving ∼100% conversion. Surprisingly, the NaOH substrate achieved optimum saccharification with only 8 FPU/g glucan. Glucan conversions (3.6–6%) obtained with mixtures of endo-1,4-β-glucanase (EG) and β-glucosidase (βG) for the NaOH substrate were 2–6 times that of acid substrates. However, glucan conversions (15–60%) obtained with mixtures of cellobiohydrolase (CBH I) and βG on acidified glycerol substrate were 10–30% higher than those obtained for NaOH and acid substrates. The susceptibility of the substrates to enzymatic saccharification was explained by their physical and chemical attributes. Acidified glycerol pretreatment offers the opportunity to simplify the complexity of enzyme mixtures required for saccharification of lignocellulosics.

A simple test method for profiled steel cladding systems under wind uplift

A new simple test method using small scale models has been developed for testing profiled steel cladding systems under wind uplift/suction forces. This simple method should replace the large scale test method using two-span claddings used at present. It can be used for roof or wall cladding systems fastened with screw fasteners at crests or valleys.

Graphyne and graphdiyne : versatile catalysts for dehydrogenation of light metal complex hydrides

The interaction between new two-dimensional carbon allotropes, i.e. graphyne (GP) and graphdiyne (GD), and light metal complex hydrides LiAlH4, LiBH4, and NaAlH4 was studied using density functional theory (DFT) incorporating long range van der Waals dispersion correction. The light metal complex hydrides show much stronger interaction with GP and GP than that with fullerene due to the well defined pore structure. Such strong interactions greatly affect the degree of charge donation from the alkali metal atom to AlH4 or BH4, consequently destabilizing the Al-H or B-H bonds. Compared to the isolated light metal complex hydride, the presence of GP or GD can lead to a significant reduction of the hydrogen removal energy. Most interestingly, the hydrogen removal energies for LiBHx on GP and with GD are found to be lowered at all the stages (x from 4 to 1) whereas the H-removal energy in the third stage is increased for LiBH4 on fullerene. In addition, the presence of uniformly distributed pores on GP and GD is expected to facilitate the dehydrogenation of light metal complex hydrides. The present results highlight new interesting materials to catalyze light metal complex hydrides for potential application as media for hydrogen storage. Since GD has been successfully synthesized in a recent experiment, we hope the present work will stimulate further experimental investigations in this direction.

Bending properties of Ag nanowires with pre-existing surface defects

Materials used in the engineering always contain imperfections or defects which significantly affect their performances. Based on the large-scale molecular dynamics simulation and the Euler–Bernoulli beam theory, the influence from different pre-existing surface defects on the bending properties of Ag nanowires (NWs) is studied in this paper. It is found that the nonlinear-elastic deformation, as well as the flexural rigidity of the NW is insensitive to different surface defects for the studied defects in this paper. On the contrary, an evident decrease of the yield strength is observed due to the existence of defects. In-depth inspection of the deformation process reveals that, at the onset of plastic deformation, dislocation embryos initiate from the locations of surface defects, and the plastic deformation is dominated by the nucleation and propagation of partial dislocations under the considered temperature. Particularly, the generation of stair-rod partial dislocations and Lomer–Cottrell lock are normally observed for both perfect and defected NWs. The generation of these structures has thwarted attempts of the NW to an early yielding, which leads to the phenomenon that more defects does not necessarily mean a lower critical force.

Medical nutrition therapy and simple interventions can improve intake in patients who eat poorly in hospital

The Australasian Nutrition Care Day Survey (ANCDS) reported two-in-five patients in Australian and New Zealand hospitals consume ≤50% of the offered food. The ANCDS found a significant association between poor food intake and increased in-hospital mortality after controlling for confounders (nutritional status, age, disease type and severity)1. Evidence for the effectiveness of medical nutrition therapy (MNT) in hospital patients eating poorly is lacking. An exploratory study was conducted in respiratory, neurology and orthopaedic wards of an Australian hospital. At baseline, 24-hour food intake (0%, 25%, 50%, 75%, 100% of offered meals) was evaluated for patients hospitalised for ≥2 days and not under dietetic review. Patients consuming ≤50% of offered meals due to nutrition-impact symptoms were referred to ward dietitians for MNT with food intake re-evaluated on day-7. 184 patients were observed over four weeks. Sixty-two patients (34%) consumed ≤50% of the offered meals. Simple interventions (feeding/menu assistance, diet texture modifications) improved intake to ≥75% in 30 patients who did not require further MNT. Of the 32 patients referred for MNT, baseline and day-7 data were available for 20 patients (68±17years, 65% females, BMI: 22±5kg/m2, median energy, protein intake: 2250kJ, 25g respectively). On day-7, 17 participants (85%) demonstrated significantly higher consumption (4300kJ, 53g; p<0.01). Three participants demonstrated no improvement due to ongoing nutrition-impact symptoms. “Percentage food intake” was a quick tool to identify patients in whom simple interventions could enhance intake. MNT was associated with improved dietary intake in hospital patients. Further research is needed to establish a causal relationship.

Metal hexaborides with Sc, Ti or Mn

Comparison of well-determined single crystal data for stoichiometric, or near-stoichiometric, metal hexaborides con-firm previously identified lattice parameter trends using powder diffraction. Trends for both divalent and trivalent forms suggest that potential new forms for synthesis include Sc and Mn hexaborides. Density Functional Theory (DFT) calculations for KB6, CaB6, YB6, LaB6, boron octahedral clusters and Sc and Mn forms, show that the shapes of bonding orbitals are defined by the boron framework. Inclusion of metal into the boron framework induces a reduction in energy ranging from 1 eV to 6 eV increasing with ionic charge. For metals with d1 character, such a shift in energy brings a doubly degenerate band section along the G-M reciprocal space direction within the conduction bands tangential to the Fermi surface. ScB6 band structure and density of states calculations show directional and gap characteristics similar to those of YB6 and LaB6. These calculations for ScB6 suggest it may be possible to realize superconductivity in this compound if synthesized.

Role of particle size and composition in metal adsorption by solids deposited on urban road surfaces

Despite common knowledge that the metal content adsorbed by fine particles is relatively higher compared to coarser particles, the reasons for this phenomenon has gained little research attention. The research study discussed in the paper investigated the variations in metal content for different particle sizes of solids associated with pollutant build-up on urban road surfaces. Data analysis confirmed that parameters favourable for metal adsorption to solids such as specific surface area, organic carbon content, effective cation exchange capacity and clay forming minerals content decrease with the increase in particle size. Furthermore, the mineralogical composition of solids was found to be the governing factor influencing the specific surface area and effective cation exchange capacity. There is high quartz content in particles >150µm compared to particles <150µm. As particle size reduces below 150µm, the clay forming minerals content increases, providing favourable physical and chemical properties that influence adsorption.

Reply to comment on “Characterising metal build-up on urban road surfaces” by Egodawatta et al. (2013)

In the recent manuscript published by Egodawatta et al. (2013), the authors investigated the build-up process of heavy metals (HMs) associated with road-deposited sediment (RDS) on residential road surfaces, and presented empirical models for the prediction of both the surface loads and build-up rates of HMs on these surfaces...

A simple method for fabricating 3-D multilayered composite scaffolds

One limitation of electrospinning stems from the charge build-up that occurs during processing, preventing further fibre deposition and limiting the scaffold overall thickness and hence their end-use in tissue engineering applications targeting large tissue defect repair. To overcome this, we have developed a technique in which thermally induced phase separation (TIPS) and electrospinning are combined. Thick three-dimensional, multilayered composite scaffolds were produced by simply stacking individual polycaprolactone (PCL) microfibrous electrospun discs into a cylindrical holder that was filled with a 3% poly(lactic-co-glycolic acid) (PLGA) solution in dimethylsulfoxide (a good solvent for PLGA but a poor one for PCL). The construct was quenched in liquid nitrogen and the solvent removed by leaching out in cold water. This technique enables the fabrication of scaffolds composed principally of electrospun membranes that have no limit to their thickness. The mechanical properties of these scaffolds were assessed under both quasi-static and dynamic conditions. The multilayered composite scaffolds had similar compressive properties to 5% PCL scaffolds fabricated solely by the TIPS methodology. However, tensile tests demonstrated that the multilayered construct outperformed a scaffold made purely by TIPS, highlighting the contribution of the electrospun component of the composite scaffold to enhancing the overall mechanical property slate. Cell studies revealed cell infiltration principally from the scaffold edges under static seeding conditions. This fabrication methodology permits the rapid construction of thick, strong scaffolds from a range of biodegradable polymers often used in tissue engineering, and will be particularly useful when large dimension electrospun scaffolds are required.

Fuel consumption and gas emissions of an automatic transmission vehicle following simple eco-driving instructions on urban roads

Following eco-driving instructions can reduce fuel consumption between 5 to 20% on urban roads with manual cars. The majority of Australian cars have an automatic transmission gear-box. It is therefore of interest to verify whether current eco-driving instructions are e cient for such vehicles. In this pilot study, participants (N=13) drove an instrumented vehicle (Toyota Camry 2007) with an automatic transmission. Fuel consumption of the participants was compared before and after they received simple eco-driving instructions. Participants drove the same vehicle on the same urban route under similar tra c conditions. We found that participants drove at similar speeds during their baseline and eco-friendly drives, and reduced the level of their accelerations and decelerations during eco-driving. Fuel consumption decreased for the complete drive by 7%, but not on the motorway and inclined sections of the study. Gas emissions were estimated with the VT-micro model, and emissions of the studied pollutants (CO2, CO, NOX and HC) were reduced, but no di erence was observed for CO2 on the motorway and inclined sections. The di erence for the complete lap is 3% for CO2. We have found evidence showing that simple eco-driving instructions are e cient in the case of automatic transmission in an urban environment, but towards the lowest values of the spectrum of fuel consumption reduction from the di erent eco-driving studies.

Production of metal oxide nanoparticles

Particles having at least regions of at least one metal oxide having nano-sized grains are produced by providing particles of a material having an initial, nonequiaxed particle shape, prepg. a mixt. of these particles and at last one metal oxide precursor, and treating the mixt. such that the precursor reacts with the particles. The process can be a co-pptn. process, sol-gel synthesis, micro-emulsion method, surfactant-based process, or a process that uses polymers. Complex metal oxide nanoparticles are produced by (a) prepg. a soln. contg. metal cations, (b) mixing the soln. with a surfactant to form micelles within the soln., and (c) heating the micellar liq. to form metal oxide and to remove the surfactant. The formed metal oxide particles have essentially the same morphol. (particle size and shape) as the initial morphol. of the material particles provided. [on SciFinder(R)]

Torsional properties of bamboo-like structured Cu nanowires

Recently, researchers reported that nanowires (NWs) are often polycrystalline, which contain grain or twin boundaries that transect the whole NW normal to its axial direction into a bamboo like structure. In this work, large-scale molecular dynamics simulation is employed to investigate the torsional behaviours of bamboo-like structured Cu NWs. The existence of grain boundaries is found to induce a considerably large reduction to the critical angle, and the more of grain boundaries the less reduction appears, whereas, the presence of twin boundaries only results in a relatively smaller reduction to the critical angle. The introduction of grain boundaries reduces the torsional rigidity of the NW, whereas, the twin boundaries exert insignificant influence to the torsional rigidity. NWs with grain boundaries are inclined to produce a local HCP structure during loading, and the plastic deformation is usually evenly distributed along the axial axis of the NW. The plastic deformation of both perfect NW and NWs with twin boundaries is dominated by the nucleation and propagation of parallel intrinsic stacking faults. This study will enrich the current understanding of the mechanical properties of NWs, which will eventually shed lights on their applications.

Engineering based problem solving in the middle school : design and construction with simple machines

Incorporating engineering concepts into middle school curriculum is seen as an effective way to improve students’ problem-solving skills. A selection of findings is reported from a science, technology, engineering and mathematics (STEM)-based unit in which students in the second year (grade 8) of a three-year longitudinal study explored engineering concepts and principles pertaining to the functioning of simple machines. The culminating activity, the focus of this paper, required the students to design, construct, test, and evaluate a trebuchet catapult. We consider findings from one of the schools, a co-educational school, where we traced the design process developments of four student groups from two classes. The students’ descriptions and explanations of the simple machines used in their catapult design are examined, together with how they rated various aspects of their engineering designs. Included in the findings are students’ understanding of how their simple machines were simulated by the resources supplied and how the machines interacted in forming a complex machine. An ability to link physical materials with abstract concepts and an awareness of design constraints on their constructions were apparent, although a desire to create a ‘‘perfect’’ catapult despite limitations in the physical materials rather than a prototype for testing concepts was evident. Feedback from teacher interviews added further insights into the students’ developments as well as the teachers’ professional learning. An evolving framework for introducing engineering education in the pre-secondary years is proposed.

Generation of active surface states of gold and the role of such states in electrocatalysis

The cyclic voltammetry behaviour of gold in aqueous media is often regarded in very simple terms as a combination of two distinct processes, double layer charging/discharging and monolayer oxide formation/removal. This view is questioned here on the basis of both the present results and earlier independent data by other authors. It was demonstrated in the present case that both severe cathodization or thermal pretreatment of polycrystalline gold in acid solution resulted in the appearance of substantial Faradaic responses in the double layer region. Such anamolous behaviour, as outlined recently also for other metals, is rationalized in terms of the presence of active metal atoms (which undergo premonolayer oxidation) at the electrode surface. Such behaviour, which is also assumed to correspond to that of active sites on conventional gold surfaces, is assumed to be of vital importance in electrocatalysis; in many instances the latter process is also quite marked in the double layer region.