RESUMEN

Honeybees are important pollinators, but they are continuously exposed to a variety of fungal and bacterial diseases. One of the various diseases affecting honeybees is nosemosis caused by microsporidia from the Nosema genus. Honeybees are mainly infected through consumption of infected food or faeces containing Nosema spp. spores. Nosemosis causes damage to the middle intestine epithelium, which leads to food absorption disorders and honeybee malnutrition. Fumagillin, i.e., the antibiotic used to treat nosemosis, was withdrawn in 2016 from EU countries. Therefore, researchers have been looking for compounds of both natural and synthetic origin to fight nosemosis. Such compounds should not have a negative impact on bees but is expected to inhibit the disease. Natural compounds tested against nosemosis include, e.g., essential oils (EOs), plant extracts, propolis, and bacterial metabolites, while synthetic substances tested as anti-nosemosis agents are represented by porphyrins, vitamins, antibiotics, phenolic, ascorbic acids, and others. This publication presents an 18-year overview of various studies of a number of natural and synthetic compounds used in the treatment and prevention of nosemosis cited in PubMed, GoogleScholar, and CrossRef.

RESUMEN

Palythoa spp. corals and some other marine organisms contain one of the most poisonous substances ever known - palytoxin (PTX). Due to their modest life requirements and ease of breeding, these corals are popular in home aquariums. Here we refer to a case of PTX poisoning of a middle-aged woman who inhaled poisonous vapours while brushing the corals from live rock and compare it with the available literature. As the case revealed that the symptoms of PTX poisoning are not specific and neither is treatment, our aim was to give a brief tabulated review of the symptoms that may indicate such poisoning. Cases of palytoxin poisoning have been reported worldwide, and severe ones (mostly due to ingestion of contaminated sea food) can end in death. As it appears, most (if not all) poisonings result from unawareness of the risk and reckless handling by aquarists. This is one of the first articles which provides some practical advice about the use of personal protection equipment, including gloves, masks, eyewear, and other clothing during any coral manipulation to minimise the risk. We also draw attention to the lack of marketing/trading regulations for dangerous coral species and/or regulations or instructions dealing with their removal and health protection.

Asunto(s)

RESUMEN

We examined age-related biochemical and histological changes in the fat bodies and hemolymph of Osmia rufa males and females. We analysed solitary bees during diapause, in October and in April; as well as the flying insects following diapause, in May and June. The trophocyte sizes, as well as the numbers of lipid droplets were the greatest at the beginning of diapause. Subsequently, they decreased along with age. Triglyceride and glucose concentrations systematically decreased in fat body cells but increased in the hemolymph from October to June. Concentrations/activities of (enzymatic and non-enzymatic) antioxidant and proteolytic systems, as well as phenoloxidase, aspartate aminotransferase, alanine aminotransferase and alkaline phosphatase levels were constant during the diapause, usually lower in the males than the females. Prior to the diapause/overwintering, the concentrations/activities of all the compounds were higher in the fat bodies than in the hemolymph. Later in the spring and in the summer, they increased in the hemolymph and on the body surfaces, while decreasing in the fat bodies. The global DNA methylation levels increased with age. Higher levels were always observed in the males than in the females. The study will promote better understanding of bee evolution and will be useful for the protection and management of solitary bees, with benefits to the environment and agriculture.

Asunto(s)

RESUMEN

Synthetic piezoelectric crystals in the P321 crystal class have been a focus of substantial research that is largely driven by applications in high-temperature resonant BAW and SAW sensing. Fully ordered crystals in this class, such as Ca3TaGa3Si2O14 (CTGS), have been suggested as offering the potential of electroacoustic performance that is superior to more extensively studied langasite (LGS) and langatate (LGT), which are partially disordered. In this study, the resonant frequencies, acoustic damping, and electrical conductivity of CTGS bulk acoustic resonators with Y-cut and (YXl)-30° crystal orientations and fundamental frequencies near 5 MHz are investigated at temperatures between ambient and 1100°C. (YXl)-30° resonators are found to have turnover temperatures near 200°C for the third and fifth overtones, in contrast to a monotonic decrease in resonant frequencies of Y-cut crystals with increasing temperature. The maximum temperature derivative of fractional changes in fifth-overtone frequency of (YXl)-30° CTGS is 40 × 10-6K-1 (near 1100°C), and this value is not greatly different from the temperature derivative of Y-cut CTGS frequencies over a broader range of temperatures. At ambient temperatures, the acoustic loss Q-1 of CTGS with both crystal orientations is found to be greater than the lowest values previously reported for LGS and LGT. The electrical conductivity of the CTGS specimens between 500°C and 1100°C is substantially lower than that previously reported for LGS. Corresponding to this lower conductivity, the piezoelectric/conductive contribution to Q-1 at elevated temperatures is reduced. Additional anelastic relaxation peaks observed between 100°C and 700°C are similar to those previously reported for LGS and LGT.

RESUMEN

Strontium titanate SrTiO3(100), (110), and (111) single crystals, undoped or donor doped with up to 1 at% La, were isothermally equilibrated at temperatures between 1523 and 1773 K in synthetic air followed by two different methods of Sr tracer deposition: ion implantation of 87Sr and chemical solution deposition of a thin 86SrTiO3 layer. Subsequently, the samples were diffusion annealed under the same conditions as before. The initial and final depth profiles were measured by SIMS. For strong La-doping both tracer deposition methods yield similar Sr diffusion coefficients, whereas for weak doping the tracer seems to be immobile in the case of ion implantation. The Sr diffusivity does not depend on the crystal orientation, but shows strong dependency on the dopant concentration supporting the defect chemical model that under oxidizing conditions the donor is compensated by Sr vacancies. A comparison with literature data on Sr vacancy, Ti, and La diffusion in this system confirms the concept that all cations move via Sr vacancies. Cation diffusion is several orders of magnitude slower than oxygen diffusion.

RESUMEN

Oxygen and gallium diffusivities in langasite were experimentally determined by analysis of diffusion profiles of 18O and 71Ga tracers by SIMS analysis as functions of temperature and doping. Strontium-enhanced diffusivities and activation energies of approximately 1.2+/-0.2 eV confirm the predominant role of oxygen vacancies in controlling the electrical conductivity of langasite at elevated temperature and oxygen partial pressure. The potential impact of high levels of porosity and the use of an oxygen primary ion beam on the accuracy of some of the data is discussed. The gallium diffusivity, with activation energy of 3.13 eV, was found to be more than two orders of magnitude lower than that of oxygen. Surface exchange measurements enabled estimation of gallium loss at elevated temperatures and oxygen partial pressure; the level is not believed to be of major concern for resonator performance.