Magnetic Structure and Origin of Insulating Behavior in the Ba2CuOsO6 System, and the Role of A-Site Ionic Size in Its Bandgap Opening: Density Functional Theory Approaches

The magnetic structure and the origin of band gap opening for Ba2CuOsO6 were investigated by exploring the spin exchange interactions and employing the spin–orbit coupling effect. It revealed that the double-perovskite Ba2CuOsO6, composed of the 3d (Cu2+) and 5d (Os6+) transition metal magnetic ions is magnetic insulator. The magnetic susceptibilities of Ba2CuOsO6 obey the Curie–Weiss law, with an estimated Weiss temperature of −13.3 K, indicating AFM ordering. From the density functional theory approach, it is demonstrated that the spin exchange interaction between Cu ions plays a major role in exhibiting an antiferromagnetic behavior in the Ba2CuOsO6 system. An important factor to understand regarding the insulating behavior on Ba2CuOsO6 is the structural distortion shape of OsO6 octahedron, which should be closely connected with the ionic size of the A-site ion. Since the d-block of Os6+ (d2) ions of Ba2CuOsO6 is split into four states (xy < xz, yz < x2–y2 < z2), the crucial key is separation of doubly degenerated xz and yz levels to describe the magnetic insulating states of Ba2CuOsO6. By orbital symmetry breaking, caused by the spin–orbit coupling, the t2g level of Os6+ (d2) ions is separated into three sublevels. Two electrons of Os6+ (d2) ions occupy two levels of the three spin–orbit-coupled levels. Since Ba2CuOsO6 is a strongly correlated system, and the Os atom belongs to the heavy element group, one speculates that it is necessary to take into account both electron correlation and the spin–orbit coupling effect in describing the magnetic insulating states of Ba2CuOsO6.

Improved Negative Bias Stress Stability of Sol–Gel-Processed Li-Doped SnO2 Thin-Film Transistors

In this study, sol–gel-processed Li-doped SnO2-based thin-film transistors (TFTs) were fabricated on SiO2/p+ Si substrates. The influence of Li dopant (wt%) on the structural, chemical, optical, and electrical characteristics was investigated. By adding 0.5 wt% Li dopant, the oxygen vacancy formation process was successfully suppressed. Its smaller ionic size and strong bonding strength made it possible for Li to work as an oxygen vacancy suppressor. The fabricated TFTs consisting of 0.5 wt% Li-doped SnO2 semiconductor films delivered the field-effect mobility in a 2.0 cm2/Vs saturation regime and Ion/Ioff value of 1 × 108 and showed enhancement mode operation. The decreased oxygen vacancy inside SnO2 TFTs with 0.5 wt% Li dopant improved the negative bias stability of TFTs.

Critical Level of Magnesium for Cowpea [Vigna unguiculata (L.) Walp.] in Ultisols of Kerala

Background: Ultisols are characterized by low pH, low cation exchange capacity and low base saturation due to dominance of kaolinite and oxides and hydrous oxides of iron and aluminium. Among the basic cations, magnesium has smaller ionic size and larger hydrated radius which limits binding of Mg to soil exchange sites. As a result the deficiency of magnesium is a common nutritional disorder in these soils due to leaching of bases under humid tropical conditions. The determination of critical level of magnesium in soil and plant helps to manage the nutrient deficiency and will help to avoid crop loss.Methods: A pot culture experiment was conducted to determine the critical level of magnesium for cowpea in Ultisols of Kerala during January 2019. Graded doses of magnesium were applied @ 5 mg kg-1 to 80 mg kg-1 of soil as magnesium carbonate along with recommended dose of fertilizers to evaluate the effect of applied magnesium on soil pH, available magnesium in soil, magnesium content in plant, crop uptake and yield.Result: Soil pH and available magnesium in soil recorded at flowering and harvest was highest where magnesium was applied @ 80 mg kg-1 of soil. Magnesium content in stem and leaves was found to increase with the levels of magnesium added. No significant variation in the content of magnesium in pods was recorded. Crop uptake (66.62 mg g-1) of magnesium and yield per plant (79.33 g plant-1) was highest in the treatment (T5) where magnesium was applied @ 10 mg kg-1 of soil. The critical level of magnesium determined by Cate and Nelson graphical method was found to be 75 mg kg-1 of available magnesium in soil and 0.38% in leaves of cowpea during flowering.

Potentiation of Rocuronium Bromide by Lithium Carbonate: A Case Report

Lithium carbonate is a medication used for the management of various mental disorders. The present report describes a case of prolongation of rocuronium bromide in a patient concurrently taking lithium carbonate. A 64-year-old woman was scheduled to undergo cystectomy under general anesthesia. The patient took lithium carbonate (600 mg/d) for treatment of bipolar affective disorder. General anesthesia was induced with propofol, fentanyl, remifentanil, and sevoflurane. After loss of consciousness, rocuronium bromide (50 mg) was administered, and the trachea was intubated. Approximately 1 hour after the administration of rocuronium, the degree of residual muscle relaxant was evaluated using a nerve stimulation device. No muscle contraction occurred with train-of-four (TOF) stimulation. Following administration of sugammadex (200 mg) the TOF ratio increased to 95%. The ionic size of lithium is similar to that of sodium; therefore, lithium is transported into the cell with sodium. The resting membrane potential decreases, leading to a reduction in the height of the action potential. Thus, the effect of the remaining lithium may have been superimposed on the rocuronium neuromuscular blockade. Evaluation with a nerve stimulation device in patients taking lithium is crucial before extubation because of the risk of rocuronium potentiation.

Leaching pattern of phosphate glass fertilizers with different compositions under Soxhlet distillation conditions

Glass fertilizers in the phosphate systems were melted at 900-950 °C with a soaking period of 1 h. Leaching study of these glasses with a maximum time period of 300 h was conducted under Soxhlet distillation condition with distilled water. Weight loss and the leach rates of the glass fertilizer samples were calculated from BET surface area measurements. They were in the range of 6.3x10-3 to 2.3x10-3 g.m-2.h-1 at 90 °C. The effect of different modifier ions like Na+, Fe3+, Mg2+, Ca2+, and K+ in the basic phosphate networks on melting and time of melting has been found to be evident. The pH determination ranging from 4.80 up to 7.50 of the leachate solution at ambient temperature under varying time intervals showed interesting and regular variations. The leaching study of such glasses under Soxhlet condition showed Ca2+, Mg2+, and K+ to be good candidates as modifier towards faster leaching. The findings have been corroborated in terms of ionic size, ionic radius, and hence the ionic potential of the modifier ions incorporated into the glass structure. The application of glass fertilizers was made on kharif paddy.