Gallium Suboxide Vapor Attack of Chromium,Cobalt, Molybdenum,Tungsten, and Their Alloys at 1200°C

Our prior work elucidated the failure mechanism of furnace materials (304 SS, 316 SS, and Hastelloy C-276) exposed to gallium suboxide (Ga₂O) and/or gallium oxide (Ga₂O₃) during plutonium–gallium compound processing. Failure was hypothesized to result from concurrent alloy oxidation/Ga compound reduction followed by Ga uptake. The aim of the current work is to screen candidate replacement materials. Alloys Haynes 25 (49 Co–20 Cr–15 W–10 Ni–3 Fe–2 Mn–0.4 Si, wt.%), 52 Mo–48 Re (wt.%), 62 W–38 Cu (wt.%), and commercially pure Cr, Co, Mo, W, and alumina were examined. Preliminary assessments of commercially pure W and Mo–Re suggest that these materials may be suitable for furnace construction. Thermodynamic calculations indicating that materials containing Al, Cr, Mn, Si, and V would be susceptible to oxidation in the presence of Ga₂O were validated by experimental results. The extent of attack (oxidation, Ga uptake, and elemental redistribution) cannot be predicted based on a simple rule of elemental mixtures—alloy composition plays a strong role. In contrast to that reported previously, an alternate reaction mechanism for Ga uptake, which does not require concurrent alloy oxidation, controls Ga uptake for certain materials. Due to the lack of thermodynamic data, calculations cannot quantitatively predict Ga uptake. However, a correlation between Ga solubility and uptake was noted.     

Innate Responses to Putative Ancestral Hosts: Is the Attraction of Western Flower Thrips to Pine Pollen a Result of Relict Olfactory Receptors?

Pollinophagy is widely documented in the order Thysanoptera, with representative individuals from six of the nine divergent families known to feed on pollen. Various pollens of the genus Pinus increase the development time, fecundity, longevity, and settling preference of Western Flower Thrips (WFT), Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae). Certain species of flower thrips discriminate among pollen types, but no studies have elucidated the olfactory cues that play a role in their pollen preferences. In this study, the volatile organic compounds emitted by pollens of the genus Pinus were elucidated. Various chemicals from pollen headspace elicited electrophysiological responses from WFT antennae. The compound (S)-(-)-verbenone, identified in pollen headspace, attracted WFT in a 4-arm olfactometer. This compound has potential for use in integrated pest management programs against the pest. We present the hypothesis that this polyphagous insect may have retained ancestral ‘relict’ olfactory receptors through the course of evolution, to explain this attraction to pine pollen. This attraction has allowed the insect to find and exploit an unusual nutrient source that significantly increases its fitness. The study demonstrates how fossil record analysis and subsequent evolutionary knowledge can aid in explaining possibilities as to why some insects sense and respond to chemicals that would otherwise seem peculiar to their ecology, allowing insight into the evolutionary forces that may shape insect olfactory systems over time.     

Authentication of the therapeutic Lamiaceae taxa by using pollen traits observed under scanning electron microscopy

Herbal medicines are gaining popularity worldwide for human healthcare because of their therapeutic potential. However, adulteration and use of unauthentic raw herbals as substitutes have become a major issue for the local communities and industry for reasons of safety and efficacy. Therefore, the authentication of medicinal plants before their use in herbal medicines is a need of time. Hence, the present study was designed with an aim, to authenticate the therapeutic Lamiaceous taxa by using pollen traits observed under scanning electron microscopy. Pollen micro-morphological studies solve the problem through discrimination and correct identification of the Lamiaceae species from the adulterants. Based on pollen features, Lamiaceae were further divided into two sub-families Lamioideae (tricolpate) and Nepetoideae (hexa-colpate). The pollen grains of Lamioideae were found as small to medium-sized, tricolpate, radially/bilateral symmetrical, sub-spheroidal and oblate shape. Besides, exine patterns bireticulate, reticulate and micro-reticulate, colpus surface sculpturing as psilate, gemmate, scabrate, and verrucate have also been reported. A significant variation was found in the pattern of the reticulum, thickness, and the number of secondary lumina per primary lumen. Similarly, Nepetoideae has a hexa zono-colpate pollen but tri and tetra zono-colpate pollen have also been observed. Hence, this study contributes to the authentication and correct identification of medicinally important Lamiaceae taxa by using scanning electron microscopic techniques and can help to solve the adulteration problem. Highlights

• Authentication of medicinally important Lamiceous taxa was carried out through scanning electron microscopic techniques.
• Chemotaxonomic characterization was used for the accurate identification of the therapeutic taxa.
• The medicinal, palynological and phytochemical significance of Lamiaceae taxa were evaluated.
• A significant variation was seen in the palynological traits that help in the determination and authentication of the therapeutic Lamiaceous species.
• Based on the chemotaxonomic characterization, our study can help to solve the adulteration problem for the reason of safety and efficacy.

     

Identification of novel nonedible oil seeds via scanning electron microscopy for biodiesel production

Exploration of substitute energy feed‐stocks is the much‐debated topic in the scientific society due to increasing power crises and related ecological concerns. As a source of sustainable energy, biodiesel turns out to be the best alternative to petro fuels. In this context, nonedible oil‐producing seeds might be a potential source for biodiesel production owing to their environment‐friendly nature and cost‐effectiveness. The current study, consequently, deals with the investigation and identification of micro‐morphological characters between six novel nonedible oil‐bearing seeds employing scanning electron microscopy as possible biodiesel feed‐stocks. Light microscopic examinations show that seed size varies from 0.3 to 1.3 cm in width and 0.5 to 1.5 cm in. Additionally, a large difference in seed color ranges from dark brown, black, and various shades of light brown was also witnessed. The FFA content of the seeds ranges in 0.3–4.1 mg KOH/g, and the seed oil content fall in 30–65% (w/w) range. SEM‐mediated seed ultrastructure investigations displays greater variation in seed size, shape, color, periclinal wall shape, and sculpturing and so on. All the seeds differ from rounded, ovoid, ovate, oblong, flattened, and elliptical shape. Greater variation in seed wall structure has been seen from angular, entire, irregular, straight, elongated, smooth, and polygonal. The periclinal wall arrangements show alteration from flat, depressed, elevated, smooth, pentagonal, bullate, and coarse seed margins. The results obtained from the current study suggest that scanning electron microscopy could be a beneficial tool in vitalizing the hidden micromorphological characters among various nonedible oil producing seeds, which eventually helps in exploration, correct identification, seed classification, and authentication in future.     

盾构刀盘结构设计与分析

盾构是目前土质或以土质为主隧道(洞)工程施工的优选装备,其刀盘结构是实现掌子面稳定、进行隧洞开挖掘进的关键部件.目前盾构刀盘结构主要是辐条式、辐板式和辐条辐板复合结构;大中型盾构刀盘一般采用中间支承形式;为方便刀具更换作业,大型盾构机刀盘已设计出常压刀具更换臂(辐条).此文还对刀盘上刀具布置的刀间距、布置形式等进行了总...