The influence of spiral jet-milling on the physicochemical properties of carbamazepine form III crystals: Quality by design approach

The purpose of this study was to investigate the influence of spiral jet-milling process on the physicochemical characteristics of α polymorphic active pharmaceutical ingredient, using Carbamazepine form III as a model drug, and taking into consideration Quality by Design (QbD) approach to pharmaceutical development. A 2^(4-1) factorial screening design was implemented to identify the spiral jet-milling process variables that significantly affect the particle size distribution of milled samples. Diameter of injector nozzles, diameter of ring nozzles and air pressure were selected for further analysis using a 2^(3-1) factorial experimental design. Particle size distribution of additional samples was determined, while physicochemical properties were examined by differential scanning calorimetry (DSC), hot-stage polarized microscopy (HSPM), attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), and compared to those of un-milled drug. The gathered results shown that applied experimental design approach is capable to predict material behavior and could help in better understanding of material behavior during jet-milling process. Created design space (DS) provides assurance of product quality, expressed as the powder particle sizes lower than 5 μm, as well as, in initial polymorph form existence after jet-milling through combination and interaction of input variables.     

An unprecedented bonding mode for potassium within a PCP-pincer palladium hydride–K-Selectride complex

The reaction of (PCP)^i-PrPdCl and the commonly-used reductant K-Selectride^® solution [K(sec-Bu₃BH) in THF] does not yield a simple (PCP)^i-PrPdH species, but rather an adduct of the Pd–H that contains bound K(sec-Bu₃BH). This adduct has been characterized by X-ray crystallography and shown to be a centrosymmetric dimer in the solid state. The most unique feature of the structure is that the tri-coordinate K⁺ ion bonds only to the terminal palladium hydride and the two bridging boron hydrides. Despite being prepared in THF, no other donor ligands are bound to K⁺. This [H₃K]⁺ bonding mode for K⁺ ions has not been previously reported.     

Solid oxide derived from waste shells of Turbonilla striatula as a renewable catalyst for biodiesel production

Biodiesel production via transesterification of mustard oil with methanol using solid oxide catalyst derived from waste shell of Turbonilla striatula was investigated. The shells were calcined at different temperatures for 4 h and catalyst characterizations were carried out by X-ray diffraction (XRD), scanning electron microscope (SEM), energy dispersive spectrometer (EDS), Fourier transform infrared spectrometer (FT-IR), thermogravimetric analysis (TGA)/differential scanning calorimetry (DSC) and Brunauer-Emmett-Teller (BET) surface area measurements . Formation of solid oxide i.e. CaO was confirmed at calcination temperature of 800 °C. The effect of the molar ratio of methanol to oil, the reaction temperature, catalyst calcination temperature and catalyst amount used for transesterification were studied to optimize the reaction conditions. Biodiesel yield of 93.3% was achieved when transesterification was carried out at 65 ± 5 °C by employing 3.0 wt.% catalyst and 9:1 methanol to oil molar ratio. BET surface area indicated that the shells calcined in the temperature range of 700 °C-900 °C exhibited enhanced surface area and higher pore volume than the shells calcined at 600 °C. Reusability of the catalysts prepared in different temperatures was also investigated.     

Electrochemical machining: new possibilities for micromachining

A better understanding of high rate anodic dissolution processes is urgently required for electrochemical micromachining (EMM) to become a widely employed manufacturing process in the electronic and precision manufacturing industries particularly in the micromanufacturing domain. A successful attempt has been made to develop an EMM setup for carrying out in depth independent research for achieving satisfactory control of electrochemical machining process parameters to meet the micromachining requirements. The developed EMM setup mainly consists of various sub-components and systems, e.g., mechanical machining unit, microtooling system, electrical power and controlling system and controlled electrolyte flow system, etc. All these system components are integrated in such a way that the developed EMM system setup will be capable of performing basic and fundamental research in the area of EMM fulfilling the requirements of micromachining objectives.     

On the complex electrical conductivity of poly(2,5-furandiylvinylene)

Summary The presented paper deals with the ac-conductivity of undoped and doped poly(2,5-furandiylvinylene) (PFV). It is shown that the electrical conductivity as a complex physical quantity has to be splitted into a real and an imaginary part. Both parts depend on frequency, temperature, type and concentration of doping agents, and external pressure applied to the test specimens.     

The application of Ramo's theorem to the impulse response calculation of a reach-through avalanche photodiode

A method for calculation the impulse response of a depletion layer of a semiconductor device based on Ramo's theorem is described. Using this method the impulse response of a reach-through avalanche photodiode is derived.     

Steam Oxidation Behavior of Advanced Steels and Ni-Based Alloys at 800 °C

This publication studies the steam oxidation behavior of advanced steels (309S, 310S and HR3C) and Ni-based alloys (Haynes^® 230^®, alloy 263, alloy 617 and Haynes^® 282^®) exposed at 800 °C for 2000 h under 1 bar pressure, in a pure water steam system. The results revealed that all exposed materials showed relatively low weight gain, with no spallation of the oxide scale within the 2000 h of exposure. XRD analysis showed that Ni-based alloys developed an oxide scale consisting of four main phases: Cr₂O₃ (alloy 617, Haynes^® 282^®, alloy 263 and Haynes^® 230^®), MnCr₂O₄ (alloy 617, Haynes^® 282^® and Haynes^® 230^®), NiCr₂O₄ (alloy 617) and TiO₂ (alloy 263, Haynes^® 282^®). In contrast, advanced steels showed the development of Cr₂O₃, MnCr₂O₄, Mn₇SiO₁₂, FeMn(SiO₄) and SiO₂ phases. The steel with the highest Cr content showed the formation of Fe₃O₄ and the thickest oxide scale.