Applying HYDRUS to flow in a sodic clay soil with solution composition–dependent hydraulic conductivity

Management of sodic soils under irrigation often requires application of chemical ameliorants to improve permeability combined with leaching of excess salts. Modeling irrigation, soil treatments, and leaching in these sodic soils requires a model that can adequately represent the physical and chemical changes in the soil associated with the amelioration process. While there are a number of models that simulate reactive solute transport, UNSATCHEM and HYDRUS-1D are currently the only models that also include an ability to simulate the impacts of soil chemistry on hydraulic conductivity. Previous researchers have successfully applied these models to simulate amelioration experiments on a sodic loam soil. To further gauge their applicability, we extended the previous work by comparing HYDRUS simulations of sodic soil amelioration with the results from recently published laboratory experiments on a more reactive, repacked sodic clay soil. The general trends observed in the laboratory experiments were able to be simulated using HYDRUS. Differences between measured and simulated results were attributed to the limited flexibility of the function that represents chemistry-dependent hydraulic conductivity in HYDRUS. While improvements in the function could be made, the present work indicates that HYDRUS-UNSATCHEM captures the key changes in soil hydraulic properties that occur during sodic clay soil amelioration and thus extends the findings of previous researchers studying sodic loams.

Solution chemistry impacts on the seawater neutralisation process: Benefits of nanofiltered seawater and reverse osmosis brine

It is well known that the neutralisation of Bayer liquor with seawater causes the precipitation of stable alkaline products and a reduction in pH and dissolved metal concentrations in the effluent. However, there is limited information available on solution chemistry effects on the stability and reaction kinetics of these precipitates. This investigation shows the influence of reactive species (magnesium and calcium) in seawater on precipitate stabilities and volumetric efficiencies during the neutralisation of bauxite refinery residues. Correlations between synthetic seawater solutions and real samples of seawater (filtered seawater, nanofiltered seawater and reverse osmosis brine) have been made. These investigations have been used to confirm that alternative seawater sources can be used to increase the productivity potential of the neutralisation process with minimal implications on the composition and stability of precipitates formed. The volume efficiency of the neutralisation process using synthetic analogues has been shown to be almost directly proportional with the concentration of magnesium. This was further confirmed in the nanofiltered seawater and reverse osmosis brine that showed increases in the efficiency of neutralisation by factors of 3 and 2 compared to seawater, which corresponds with relatively the same increase in the concentration of magnesium in these alternative seawater sources. An assessment of the chemical stability of the precipitates, volumetric efficiency, and discharge water quality have been determined using numerous techniques that include pH, conductivity, inductively coupled plasma optical emission spectroscopy, infrared spectroscopy, thermogravimetric analysis coupled to mass spectrometry and X-ray diffraction. Correlations between synthetic solution compositions and alternative seawater sources have been used to determine if alternative seawater sources are potential substitutes for seawater based on improvements in productivity, implementation costs, savings to operations and environmental benefits.

Group 14 element-based non-centrosymmetric quantum spin hall insulators with large bulk gap

To date, a number of two-dimensional (2D) topological insulators (TIs) have been realized in Group 14 elemental honeycomb lattices, but all are inversionsymmetric. Here, based on first-principles calculations, we predict a new family of 2D inversion-asymmetric TIs with sizeable bulk gaps from 105 meV to 284 meV, in X2–GeSn (X = H, F, Cl, Br, I) monolayers, making them in principle suitable for room-temperature applications. The nontrivial topological characteristics of inverted band orders are identified in pristine X2–GeSn with X = (F, Cl, Br, I), whereas H2–GeSn undergoes a nontrivial band inversion at 8% lattice expansion. Topologically protected edge states are identified in X2–GeSn with X = (F, Cl, Br, I), as well as in strained H2–GeSn. More importantly, the edges of these systems, which exhibit single-Dirac-cone characteristics located exactly in the middle of their bulk band gaps, are ideal for dissipationless transport. Thus, Group 14 elemental honeycomb lattices provide a fascinating playground for the manipulation of quantum states.

Inhibition by poly(acrylic acid) and morphological changes in calcium carbonate and calcium carbonate/calcium sulfate crystallization on silica fibers

An intrinsic exposed core optical fiber sensor (IECOFS) made from fused silica was used to monitor the crystallization of calcium carbonate (CaCO3) and CaCO3/calcium sulfate (CaSO4) composite at 100 and 120 °C in the absence and presence of low-molar-mass (Mn ≤ 2000) poly(acrylic acid) (PAA) with different end groups. The IECOFS responded only to deposition and growth processes on the fiber surface rather than changes occurring in the bulk of the solution. Hexyl isobutyrate-terminated PAA (Mn = 1400) and hexadecyl isobutyrate-terminated PAA (Mn = 1700) were the most effective species in preventing CaCO3 deposition. Phase transformation from vaterite to aragonite/calcite decreased with increasing hydrophobicity of the PAA end group. Low-molar-mass PAA at 10 ppm showed very significant inhibition of CaCO3/CaSO4 composite formation for all end groups investigated.

A 3-hour quantitative comparison of glucose-based versus rice-based oral rehydration solution intake by children with diarrhoea in Port Moresby General Hospital

Measurements were made of the intake of a WHO/UNICEF glucose-based and a rice cereal-based oral rehydration solution (ORS) by children with diarrhoea. Twenty children who presented to the Children's Outpatient Department at Port Moresby General Hospital with acute diarrhoea and mild dehydration were randomly assigned to an ORS and measurements were taken over the following 3 hours. For data analysis, the patients were paired by weight. Testing the means of the paired samples by t test showed that there was no significant difference between the amount of rice ORS and the amount of glucose ORS taken over 3 hours. The discovery of oral rehydration solution (ORS) for the treatment of diarrheal disease has been heralded as the most important medical discovery of the century. Cereal-based ORS is able to decrease stool output and the duration of diarrheal illness more than the standard glucose-based ORS, through the increased absorption provided by oligosaccharides without the imposition of a greater osmotic penalty. Moreover, the peptides in cereals enhance amino acid and water absorption, while providing nutritional benefits. UNICEF's glucose-based ORS is becoming more widely used in Papua New Guinea (PNG). 20 children aged 6-37 months (mean age, 15 months) who presented to the Children's Outpatient Department at Port Moresby General Hospital during September-October 1993 with acute diarrhea and mild dehydration were randomly assigned to receive either a rice-based ORS or standard glucose ORS, and measurements were taken over the following 3 hours. The patients were paired by weight for analysis. No statistically significant difference was found between the amount of rice ORS and the amount of glucose ORS taken over 3 hours.

Acceptability of a rice-based oral rehydration solution in Port Moresby General Hospital's Children's Outpatient Department

The guardians of children brought to the Port Moresby General Hospital's Children's Outpatient Department with a chief complaint of diarrhoeal disease were questioned regarding their preference of glucose-based vs rice-based oral rehydration solution (ORS) in order to determine the acceptability of a rice-based ORS. Of the 93 guardians interviewed, greater than 60% preferred the glucose-based solution in its mixability, appearance and taste, and 65% initially reported that their children preferred the taste of the glucose solution. However, after a 30-minute trial, only 58% of children still preferred the glucose solution. In a country where diarrhoeal disease is a leading cause of child death and guardians are the primary health care providers, the acceptability of an ORS is critical to the morbidity and mortality of Papua New Guinea's children. Killing an estimated 2.9 million children annually, diarrheal disease is the second leading cause of child mortality worldwide. Diarrheal disease is also the second leading cause of child mortality in Papua New Guinea (PNG), killing an average 193 inpatient children per year over the period 1984-90. However, despite the high level of diarrhea-related mortality and the proven efficacy of oral rehydration therapy (ORT) in managing diarrhea-related dehydration, standardized ORT has been underutilized in PNG. The current glucose-based oral rehydration solution (ORS) does not reduce the frequency or volume of a child's diarrhea, the most immediate concern of caregivers during episodes of illness. Cereal-based ORS, made from cereals which are commonly available as food staples in most countries, better address the short-term concerns of caregivers while offering a superior nutritional profile. A sample of guardians of children brought to the Port Moresby General Hospital's Children's Outpatient Department complaining of child diarrhea were asked about their preferences on glucose-based versus rice-based ORS in order to determine the acceptability of a rice-based ORS. More than 60% of the 93 guardians interviewed preferred the glucose-based solution for its mixability, appearance, and taste. 65% initially reported that their children preferred the taste of the glucose solution. However, after a 30-minute trial, only 58% of children still preferred the glucose solution.

Treatment of distal intestinal obstruction syndrome in cystic fibrosis with a balanced intestinal lavage solution

Conventional treatment of distal intestinal obstruction syndrome (DIOS) with high doses of pancreatic enzymes, mucolytic agents, and enemas is neither predictably effective nor rapid in action. In 6 cystic fibrosis patients with DIOS a balanced, non-absorbable intestinal lavage solution produced clinical and radiological improvement and striking improvement in DIOS scores. It is suggested that a balanced intestinal lavage solution should be considered as an alternative treatment for DIOS in patients with cystic fibrosis.

Single household domestic water heater design and control utilising PV energy: The untapped energy storage solution

Photovoltaic (PV) panels and electric domestic water heater with storage (DWH) are widely used in households in many countries. However, DWH should be explored as an energy storage mechanism before batteries when households have excess PV energy. Through a residential case study in Queensland, Australia, this paper presents a new optimized design and control solution to reduce water heating costs by utilizing existing DWH energy storage capacity and increasing PV self-consumption for water heating. The solution is produced by evaluating the case study energy profile and numerically maximizing the use of PV for DWH. A conditional probability matrix for different solar insolation and hot water usage days is developed to test the solution. Compared to other tariffs, this solution shows cost reduction from 20.8% to 63.3% This new solution could encourage solar households move to a more economical and carbon neutral water heating method.

Open-pit block sequencing optimization: A mathematical model and solution technique

This study presents a comprehensive mathematical formulation model for a short-term open-pit mine block sequencing problem, which considers nearly all relevant technical aspects in open-pit mining. The proposed model aims to obtain the optimum extraction sequences of the original-size (smallest) blocks over short time intervals and in the presence of real-life constraints, including precedence relationship, machine capacity, grade requirements, processing demands and stockpile management. A hybrid branch-and-bound and simulated annealing algorithm is developed to solve the problem. Computational experiments show that the proposed methodology is a promising way to provide quantitative recommendations for mine planning and scheduling engineers.

The Newcastle solution: A realist perspective

This intervention was a multi-component program where a number of different strategies were implemented simultaneously: • Reduced trading hours; • ‘Lockouts’; • Restrictions on the strength of alcohol after certain times; • Managerial changes to the operation of the licensed premises

Effects of glycerol on enzymatic hydrolysis and ethanol production using sugarcane bagasse pretreated by acidified glycerol solution

In this study, for the first time the effects of glycerol on enzymatic hydrolysis and ethanol fermentation were investigated. Enzymatic hydrolysis was inhibited slightly with 2.0 wt% glycerol, leading to reduction in glucan digestibility from 84.9% without glycerol to 82.9% (72 h). With 5.0 wt% and 10.0 wt% glycerol, glucan digestibility reduced by 4.5% and11.0%, respectively. However, glycerol appeared not detrimental to cellulase enzymes. Ethanol fermentation was not affected with glycerol up to 5.0 wt%, and was inhibited slightly with 10.0 wt% glycerol, which resulted in reduction in ethanol yield from 86.0% without glycerol to 83.7% (20 h). Based on laboratory and pilot scale enzymatic hydrolysis and ethanol production results, it was estimated that 0.142 kg ethanol could be produced from 1.0 kg dry bagasse (a glucan content of 38.0%) after pretreatment with acidified glycerol solution.

Organic–inorganic bismuth (III)-based material: A lead-free, air-stable and solution-processable light-absorber beyond organolead perovskites

Methylammonium bismuth (III) iodide single crystals and films have been developed and investigated. We have further presented the first demonstration of using this organic–inorganic bismuth-based material to replace lead/tin-based perovskite materials in solution-processable solar cells. The organic–inorganic bismuth-based material has advantages of non-toxicity, ambient stability, and low-temperature solution-processability, which provides a promising solution to address the toxicity and stability challenges in organolead- and organotin-based perovskite solar cells. We also demonstrated that trivalent metal cation-based organic–inorganic hybrid materials can exhibit photovoltaic effect, which may inspire more research work on developing and applying organic-inorganic hybrid materials beyond divalent metal cations (Pb (II) and Sn (II)) for solar energy applications.