Detection of carbon nanotubes in biological samples through microwave-induced heating

We demonstrate a novel technique for quantitative detection of carbon nanotubes (CNTs) in biological samples by utilizing the thermal response of CNT under microwave irradiation. In particular, rapid heating of CNT due to microwave absorption is employed to quantify CNT uptake in agricultural samples with excellent sensitivity. We inject alfalfa (Medicago sativa) roots with a known quantity of CNT (single-walled and multi-walled) and expose the samples to a microwave field (30–50 W) to generate standard temperature-CNT concentration relationships; this detection method is then used to accurately determine CNT uptake by alfalfa plant roots grown in CNT-laden soil. The threshold for detectable CNT concentration is much lower (<0.1 μg) than common analytical methods such as electron microscopy and Raman spectroscopy. Considering the lack of effective detection methods for CNT uptake in plants, our concept is not only unique but also practical, as it addresses a major problem in the field of nanomaterial characterization and nanotoxicology risk assessment.     

Identification of Ebsulfur Analogues with Broad‐Spectrum Antifungal Activity

Invasive fungal infections are on the rise due to an increased population of critically ill patients as a result of HIV infections, chemotherapies, and organ transplantations. Current antifungal drugs are helpful, but are insufficient in addressing the problem of drug‐resistant fungal infections. Thus, there is a growing need for novel antimycotics that are safe and effective. The ebselen scaffold has been evaluated in clinical trials and has been shown to be safe in humans. This makes ebselen an attractive scaffold for facile translation from bench to bedside. We recently reported a library of ebselen‐inspired ebsulfur analogues with antibacterial properties, but their antifungal activity has not been characterized. In this study, we repurposed ebselen, ebsulfur, and 32 additional ebsulfur analogues as antifungal agents by evaluating their antifungal activity against a panel of 13 clinically relevant fungal strains. The effect of induction of reactive oxygen species (ROS) by three of these compounds was evaluated. Their hemolytic and cytotoxicity activities were also determined using mouse erythrocytes and mammalian cells. The MIC values of these compounds were found to be in the range of 0.02–12.5 μg mL^?1 against the fungal strains tested. Notably, yeast cells treated with our compounds showed an accumulation of ROS, which may further contribute to the growth‐inhibitory effect against fungi. This study provides new lead compounds for the development of antimycotic agents.     

Dynamics of Population Ageing in Nepal and the Need for Action

Over the past decades, the problem of ageing has grown steadily in Nepal. The demographic measures obtained from different population censuses of Nepal amply demonstrate this. In this context, the present study attempts to analyze population census 2011 data to assess elderly population across the nation by area types, eco-belts, development regions and by gender perspective through computation of major population ageing indicators for these cross-sectional areas of Nepal. The analysis showed that the indicators like median age, proportion of elderly population, elderly dependency ratio and life expectancy at birth have increased significantly in 2011 census compared to 2001 census stressing the need of appropriate actions for the management, welfare and care of elderly people in Nepal. Even though population ageing is found more evident in urban areas regarding median age and index of ageing, percent elderly population aged 60 and above and elderly dependency are actually higher in rural areas which can be attributed to more out-migration of young people in rural areas. Eco-belt-wise, elderly dependency is found higher in mountain but other ageing indicators are at higher levels in hills. Development region-wise, western region shows relatively more ageing stress compared to other regions except that median age is found highest in the central region. Additionally, two semi-log statistical models that fit well are also built to associate percent elderly populations of Nepal with crude birth rate based upon population censuses of Nepal.     

Effect of protein concentration on the surface composition,water sorption and glass transition temperature of spray-dried skim milk powders

The effects of dilution of protein content in skim milk (34–8.5% protein content), by lactose addition, on the surface composition, water sorption property and glass transition temperatures of spray-dried powders were investigated. The X-ray photoelectron spectroscopy (XPS) study of spray-dried powders showed preferential migration of proteins toward the surface of the milk particles whereas the lactose remained in the bulk. Sorption studies showed that the lower protein concentration in milk powders is linked to an increased water adsorption property and lowering of water activity (a_w) for lactose crystallization. Analysis of glass transition temperature (T_g) of the powders sorbed at different humidities showed no distinct change in T_g values, indicating the dominant effect of lactose on the glass transition temperature of all the powders.     

Susceptibility of 5-methyltetrahydrofolic acid to heat and microencapsulation to enhance its stability during extrusion processing

Folic acid is a common form of folate used for food fortification to prevent the incidence of neural birth defects among others. However, 5-methyltetrahydrofolic acid (5-MTHF) is considered, a better alternative to folic acid and is less likely to mask the symptoms of B₁₂ deficiency in older populations. Also it is less bioavailable, and present in very low amount in foods. Fortification of foods with 5-MTHF is considered problematic, because it is highly sensitive to normal food processing operations. A comparative study on the thermal stability of folic acid and 5-MTHF in various liquid model food matrices such as milk, soymilk, starch–water and water during boiling and autoclaving at various time intervals was performed. Thermal degradation of 5-MTHF was more severe than folic acid in all food matrices e.g., almost 70% loss of 5-MTHF vs 17% loss of folic acid. Microencapsulation of 5-MTHF is considered to improve the stability of 5-MTHF during processing. A combination of pectin (P) and sodium alginate (A) at three different proportions (P60:A40, P70:A30, P80:A20) were employed for encapsulating 5-MTHF by spray drying. Microcapsules with the highest loading efficiency of 60% of vitamin (from P80:A20) and unencapsulated 5-MTHF powder was incorporated into starch and extruded at six different temperatures (100, 110, 120, 130, 140, 150 °C). The 5-MTHF had better stability (84–94.5% retention) compared to the free form (65.3–83.2%) in all extruded products. The effectiveness of encapsulation was more evident at higher extrusion temperatures.     

Thermal death kinetics of adult red flour beetle Tribolium castaneum (Herbst) in canola seeds during radio frequency heating

Thermal mortalities of adult red flour beetles Tribolium castaneum (Herbst) infesting canola seeds at various moisture contents and volumes were determined after radio frequency (RF) heating (i.e. temperature between 30 and 80°C). The mortality of 92% was achieved at the end temperature of 343 K for small-volume (1.96 × 10^?4 m³, 0.250 kg) seeds, and the mortality of 99% at 333 K for large-volume (1.77 × 10^?3 m³, 2.26 kg) seeds. Regardless of sample volume, the thermal mortalities of the test insects increased significantly after the seed temperature reached 333 K (60°C). The kinetic parameters of the thermal death of the adult T. castaneum were estimated using inverse simulation. The ordinary differential equation-based kinetic model with the Arrhenius temperature-dependent reaction rate constant was solved using the fourth-order Runge–Kutta method. The kinetics followed first-order reaction with the activation energy of 100 kJ/mol. Good agreements were observed between the mortalities predicted using the kinetic model and the experiments (R² = 0.972–0.987) except for the small-volume seeds at 11% MC (11 g/100 g raw materials) (R² = 0.741). The predicted lethal times (s) to achieve 95 and 99% mortalities using the kinetic model agreed well with those determined from the experiments.     

Effect of cryo-milling on starches: Functionality and digestibility

Four commercial starches, potato starch (PS), maize starch (MS), and two high amylose maize starches (HAMS), were cryo-milled, with and without hydration, for 20 min to study the effect of milling on physicochemical properties and enzyme digestibility. There was a significant increase in cold water soluble and damaged starch in cryo-milled samples in the order PS > MS > HAMS. Viscosity parameters of milled starches were significantly lower than for native starches, although changes in pasting temperature were not significant. In vitro digestion of native starches showed that enzyme resistance followed the order PS > HAMS > MS. A significant increase in enzyme digestion rate was observed after cryo-milling PS and HAMS but not MS. However, cryo-milled PS and HAMS were still less rapidly-digested than native MS. Scanning electron microscopy (SEM) of native, milled and digested starches showed a uniform ‘inside-out’ digestion pattern for MS, whereas a heterogeneous and nonspecific pattern was observed for PS and HAMS. This study suggests that milling has predominantly mechanical rather than thermal effects on starches and that the relative enzyme resistance of PS and HAMS granules compared with MS is due to the absence of the structural features of MS granules that allow internal access of enzymes.     

Effects of cross-border power trade between Laos and Thailand: Energy security and environmental implications

This paper analyzed the effects of hydropower development in Laos and power trade between Laos and Thailand on economy wide, energy resource mix, power generation capacity mix, energy system cost, environment, as well as, energy security. A MARKAL-based model for an integrated energy system of Laos and Thailand was developed to assess the effects of energy resource development and trade to meet the national energy demands of the two countries. Two national MARKAL-based energy system models of Laos and Thailand were formulated for the study. The results show that 80% exploitation of water resource in Laos would induce power trade between the countries. The integrated energy system cost is found to decrease marginally but it would mitigate the CO₂ emission by 2% when compared with the base case. Thailand is expected to gain benefit from the increased level of power imported from Laos in terms of the lower energy system cost, better environmental quality and, greater diversification of energy sources. As compared to the base case, Laos would become the net energy exporter, earn significant export revenue, and improve the increase in revenue of energy export per increase in total energy system cost from the maximum exploitation of hydropower resource.     

Integrated resource planning in the power sector and economy-wide changes in environmental emissions

This paper analyzes the roles of key factors (i.e., changes in structure, fuel mix and final demand) on total economy-wide changes in CO₂, SO₂ and NO_x emissions when power sector development follows the integrated resource planning (IRP) approach instead of traditional supply-based electricity planning (TEP). It also considers the rebound effect (RE) of energy efficiency improvements in the demand side and analyzes the sensitivity of the results to variations in the values of the RE. A framework is developed to decompose the total economy-wide change in the emission of a pollutant into four major components, i.e., structural change-, fuel mix- , final demand- and joint-effects. The final demand effect is further decomposed into three categories, i.e., construction of power plants, electricity final demand and final demand related to electricity using equipments. The factor decomposition framework is then applied in the case of the power sector in Indonesia. A key finding in the case of Indonesia is that in the absence of the RE, there would be total economy-wide reductions in CO₂, SO₂ and NO_x emissions of 431, 1.6 and 1.3 million tons respectively during the planning horizon of 2006–2025 under IRP as compared to that under TEP. The decomposition analysis shows that the final demand effect would account for 38% of the total CO₂ emission reduction followed by the structural change effect (35.1%) and fuel mix effect (27.6%) while the joint effect is negligible. The study also shows that economy-wide CO₂ emission reduction due to IRP considering the RE of 45% would be 241 million tons as compared to 333 million tons when the RE is 25%.     

Water sorption and glass transition properties of spray dried lactose hydrolysed skim milk powder

The moisture sorption behaviour and glass transition temperature of spray dried skim milk powder with hydrolysed lactose (SMPHL) were determined. Spray drying of skim milk with hydrolysed lactose resulted in very low cyclone recovery of 25% and a large amount of powder remained stuck inside the spray dryer. The equilibrium moisture content of SMPHL was lower than that of lactose for each range of water activity when humidified for 21 days at 23 °C using saturated salt solutions. Unlike lactose, SMPHL did not lose water when the water activity exceeded 0.432 and no crystallization was noticed at water activity ?0.753. The sorption isotherm data for SMPHL fitted well with the BET and GAB models with monolayer moisture contents of 7.55 and 8.27 g/100 g, respectively. The glass transition temperature of anhydrous SMPHL was 49 °C. The critical water activity and moisture content for SMPHL were 0.15 and 2.4 g/100 g dry solid, respectively. The low critical values indicated hydrolysis of lactose necessities maintenance of very low moisture of powder for its long-term stability.