Separation of Scaptotrigona postica Workers into Defined Task Groups by the Chemical Profile on Their Epicuticle Wax Layer

During evolution, the cuticle surface of insects acquired functions in communication, such as inter- and intra-specific recognition, identification of gender, physiological state, and fertility. In eusocial bees, the information in the cuticular surface is important not only to discriminate nestmates from non-nestmates but also to identify an individual’s class, life phase or task. A comparative study of the cuticular surface chemical profile of workers of Scaptotrigona postica in different phases of life, i.e., newly emerged workers (NE), brood comb area workers (CA), and forager workers (FO) was undertaken by gas chromatography linked to mass spectrometry. Multivariate statistical analysis was performed to verify how workers are grouped according to their chemical profile and to determine which compounds are responsible for separating them into groups. The cuticle surface of workers contains mainly hydrocarbons and a small amount of oxygenated compounds. Multivariate statistical analysis showed qualitative and quantitative variation in relation to the life phases/tasks performed, and all groups were distinct. The most abundant compound found in NE and CA was n-heptacosane, while in FO, it was (Z)-9-heptacosene. The compounds that differentiate NE from other groups are n-tricosane and n-hexacosane. A (Z)-X-octacosene and n-nonacosane are the chemicals that distinguish CA from NE and FO, while 11- and 13-methylpentacosane, (Z)-X-hexacosene, and (Z)-9-heptacosene characterize FO as distinct from NE and CA. The probable function of alkenes is nestmate recognition, mainly in FO. The results show that the cuticle surfaces of workers are characteristic of the phase of life/task performed by workers, allowing intra-colonial recognition.     

Quantifying drying performance of a filter dryer: Experiments and simulations

Drying is one of the most commonly used unit operations in the preparation of dry granules by thermally removing volatile solvent from the wet solid. The study focuses on the quantitative investigation of heat transfer in a filter dryer in the quest to determine the optimum drying conditions. Consequently, contact drying kinetics of glassbeads–ethanol and lactose–ethanol system is investigated using an agitated filter dryer (Charles Thompson). Discrete element method is employed to simulate granular flow, mixing and heat transport in the vessel. Typical system with glass beads is numerically simulated using appropriate material properties and validated by the experimental findings. A parametric study for both simulations and experiments is performed to assess the effect of various conditions of wall temperature, fill level and impeller speed on the drying performance in the filter dryer. A high wall temperature showed an increase in the drying rate and a sharp rise in the average bed temperature, thereby decreasing the total time for drying operation. An increase in fill volume (bed depth) at constant wall temperature and speed resulted in a decline in the drying rate. The rotational speed had a nominal impact on drying of glass beads. Hence low rotational speeds seemed optimal for contact drying.     

Ultra-high temperature deformation in TaC and HfC

TaC and HfC bars were thermo-mechanically tested up to 2900?°C using a non-contact loading method based on the Lorentz force. It was observed that HfC deflected more than TaC up to 2300?°C, which has been contributed to a difference in grain size facilitating diffusional creep, either Nabarro-Herring or Coble creep. Above 2500?°C, TaC continued to deflect more with temperature whereas HfC showed a reduced deflection. This reduced deflection was found to be an artifact of a preload plastic deformation response. Though both sets of samples were identified to have a prevalence of <110>{110} slip, at elevated temperatures, it appears that mass transport and diffusional creep mechanisms dominate evident by porosity in the grain boundaries. The activation energies of TaC were found to be 946?±?157?kJ/mol (between 2500–2700?°C) and HfC to be 685?±?54?kJ/mol (between 2100–2300?°C).     

Coal rib response during bench mining: A case study

In 2016, room-and-pillar mining provided nearly 40% of underground coal production in the United States.Over the past decade, rib falls have resulted in 12 fatalities, representing 28% of the ground fall fatalities in U.S.underground coal mines.Nine of these 12 fatalities(75%) have occurred in room-andpillar mines.The objective of this research is to study the geomechanics of bench room-and-pillar mining and the associated response of high pillar ribs at overburden depths greater than 300 m.This paper provides a definition of the bench technique, the pillar response due to loading, observational data for a case history, a calibrated numerical model of the observed rib response, and application of this calibrated model to a second site.     

COMPARATIVE MALTING PERFORMANCE OF OLD AND NEW BARLEY VARIETIES

A comparison was made of the malting behaviour of eight barley varieties representing a range from ancient to modern types. Plants were grown under controlled conditions in a glasshouse with two different nitrogen treatments and the grain obtained was subjected to a factorial micro-malting analysis. Under the conditions of this experiment there was little evidence of an improvement in malting ability between Plumage Archer and Ark Royal and there is limited scope for further increases in potential hot water extract. It would therefore appear that emphasis should now be given to the production of varieties with good agronomic characteristics which maintain this potential and modify rapidly without the need for abrasion and exogenous GA₃.     

Metals in mandibles of stored product insects: do zinc and manganese enhance the ability of larvae to infest seeds?

Although high concentrations of zinc and manganese were found in mandibles of insect larvae that bore into seeds, these metals were not detected in mandibles of insect larvae that attack previously damaged seeds. Metals were present in the larval mandibles of a lepidopteran, the Angoumois grain moth (Sitotroga cerealella), and eight coleopterans, the lesser grain borer (Rhyzopertha dominica), cigarette beetle (Lasioderma serricorne), drugstore beetle (Stegobium paniceum), spider beetle (Gibbium aequinoctiale), warehouse beetle (Trogoderma variabile), cadelle (Tenebroides mauritanicus), larger black flour beetle (Cynaeus angustus), and cowpea weevil (Callosobruchus maculatus). Larvae of these species can chew into seeds. Larvae of six other coleopterans, the varied carpet beetle (Anthrenus verbasci), sawtoothed grain beetle (Oryzaephilus surinamensis), rusty grain beetle (Cryptolestes ferrugineus), red flour beetle (Tribolium castaneum), longheaded flour beetle (Latheticus oryzae), and granary weevil (Sitophilus granarius) have little if any ability to chew into seeds, and did not have metal in their mandibles. Larvae of the granary weevil hatch and feed within seeds that were penetrated previously during egg deposition by adults. However, newly hatched larvae of the cowpea weevil and the Angoumois grain moth have to bore through the seed coat before they begin feeding, and they have mandibles with high concentrations of zinc. These data support the hypothesis that deposition of zinc and/or manganese in larval mandibles enhances the larva's ability to penetrate seeds.     

Aflatoxin determination in peanut butter by enzyme-linked immunosorbent assay

High specificity, high titre antisera to aflatoxins B₁ and G₁ have been produced by immunisation of rabbits with a bovine serum albumin-aflatoxin B₁ conjugate. The antiserum has been used to set up an indirect, double antibody microtitration plate enzyme-linked immunosorbent assay with a limit of detection of 0.1 pg toxin per well. The assay has been validated for application to peanut butter, and demonstrates many advantages over conventional methodology, including the requirement for minimal sample preparation before assay, its technical simplicity, and its potential high sample through-put.