A model for the current instabilities in GaAs‐AlGaAs heterojunction

A model is proposed for the description of the current instabilities in GaAs-AlGaAs heterojunctions. It consists of three parts: the injection of electrons via the contact into the AlGaAs layer, the partial capture of these electrons in deep centers, and the change with time of the band structure. This last ingredient is crucial, since due to the increase of the total number of electrons in the AlGaAs layer the band bending decreases making real-space transfer from the AlGaAs layer to the two-dimensional electron gas possible. We have performed quasistationary simulations of the time dependence of the current. The velocities, average energies, capture rates, etc. were taken from Monte Carlo simulations. It turned out, that the parameters for the modeling of the contact, which are to a high degree unknown, play an essential role

Recent advancements in the breeding of sorghum crop: current status and future strategies for marker-assisted breeding

Sorghum is emerging as a model crop for functional genetics and genomics of tropical grasses with abundant uses, including food, feed, and fuel, among others. It is currently the fifth most significant primary cereal crop. Crops are subjected to various biotic and abiotic stresses, which negatively impact on agricultural production. Developing high-yielding, disease-resistant, and climate-resilient cultivars can be achieved through marker-assisted breeding. Such selection has considerably reduced the time to market new crop varieties adapted to challenging conditions. In the recent years, extensive knowledge was gained about genetic markers. We are providing an overview of current advances in sorghum breeding initiatives, with a special focus on early breeders who may not be familiar with DNA markers. Advancements in molecular plant breeding, genetics, genomics selection, and genome editing have contributed to a thorough understanding of DNA markers, provided various proofs of the genetic variety accessible in crop plants, and have substantially enhanced plant breeding technologies. Marker-assisted selection has accelerated and precised the plant breeding process, empowering plant breeders all around the world

Response of some chickpea (Cicer arietinum L.) genotypes to salt stress conditions

The salt (NaCl) tolerance of 5 chickpea genotypes was investigated. Plants were grown in 5 different NaCl concentrations. Germination percentage, shoot and root length, shoot and root dry weight and salt tolerance percentage in the shoots and roots were evaluated. The salt tolerance index (STI) of the genotypes, expressed as the ratio of dry matter yield produced under the NaCl treatments compared to the control treatment, was found to be a reliable criterion for ranking genotypes for their tolerance to NaCl. İnci, Aydi{dotless}n-92 and FLIP 98-55C showed high levels of tolerance and İzmir-92 medium levels. FLIP 98-63C was the most susceptible genotypes to NaCl

Three-dimensional micro-culture system for tooth tissue engineering

The arrangement of cells within a tissue plays an essential role in organogenesis, including tooth development. Progress is being made to regenerate teeth by reassociating dissociated embryonic dental cells and implanting them in vivo. In the present study, we tested the hanging drop method to study mixed epithelial-mesenchymal cell reorganization in a liquid instead of semisolid medium to see whether it could lead to tooth histogenesis and organogenesis. This method allowed the control of the proportion and number of cells to be used, and the forming microtissues showed homogeneous size. The liquid environment favored cell migrations as compared with collagen gels. Three protocols were compared. The one that sequentially combined the hanging drop and semisolid medium cultures prior to in vivo implantation gave the best results. Indeed, after implantation, teeth developed, showing a well-formed crown, mineralization of dentin and enamel, and the initiation of root formation. Vascularization and the cellular heterogeneity in the mesenchyme were similar to what was observed in developing molars. Finally, after coimplantation with a trigeminal ganglion, the dental mesenchyme, including the odontoblast layer, became innervated. The real advantage of this technique is the small number of cells required to make a tooth. This experimental model can be employed to study the development, physiology, metabolism, or toxicology in forming teeth and test other cell sources