Effect of Al Addition on the Oxidation Resistance of HfC Thin Films

In this paper, we focus on the research of Al addition on Hf–Al–C film structure and oxidation resistance. It was found that obtained Hf–A–C films consist of a solid solution of Al in non-stoichiometric cubic HfC and have identical XRD patterns to bcc–HfC. Besides, the Al addition decreases the sample mass gain during oxidation in air at temperatures up to 800 °C. Mass gain for Hf–Al–C was 44.3 and 22.5% less, compared to pristine HfC, at 600 and 800 °C, respectively.

Combustibility of lightweight foam concrete based on natural protein foaming agent

There is an experimental study of samples of monolithic foam concrete “SOVBI” with a density of 205 kg /m3 (grade D200) for combustibility. The evaluation criteria are the following values of combustion characteristics: temperature increment in the furnace, duration of the stable flame burning, sample mass loss. The experimental results show the following values for foam concrete: temperature increment in the furnace of 2 °C, duration of the stable flame burning of 0 s, and sample mass of 24.4%. Thus, monolithic foam concrete with a density of 205 kg/m3 is noncombustible material. It is proposed to use monolithic foam concrete and other lightweight monolithic cellular foam concrete, as a structural fire protection for lightweight steel concrete structures. It, in turn, can increase the fire resistance of external walls and floor structure with the steel frame of cold-formed zinc-coated profiles.

Study of vibration treatment of external and internal surfaces of parts during their preparation for coating

The formation of quality parameters of the external and internal parts surfaces processed to vibration treatment in the abrasive granules is studied. Dependencies for determining of the surface roughness and processing time are obtained. The processing features of the external and internal surfaces and the differences between them are determined. It is revealed that the established roughness of the internal surface is higher than the external, and the sample mass practically does not affect on the established roughness. Technological recommendations are given for vibration technological processing design that ensure the part preparing for further coating.

Optimized sample preparation for fecal volatile organic compound analysis by gas chromatography–mass spectrometry

Introduction Headspace gas chromatography–mass spectrometry (HS-GC–MS) is widely considered the gold standard of quantitative fecal VOC analysis. However, guidelines providing general recommendations for bioanalytical method application in research and clinical setting are lacking. Objectives To propose an evidence-based research protocol for fecal VOC analysis by HS-GC–MS, based on extensive testing of instrumental and sampling conditions on detection and quantification limits, linearity, accuracy and repeatability of VOC outcome. Methods The influence of the following variables were assessed: addition of different salt solutions, injection temperature, injection speed, injection volume, septum use, use of calibration curves and fecal sample mass. Ultimately, the optimal sample preparation was assessed using fecal samples from healthy preterm infants. Fecal VOC analysis in this specific population has potential as diagnostic biomarkers, but available amount of feces is limited here, so optimization of VOC extraction is of importance. Results We demonstrated that addition of lithium chloride enhanced the release of polar compounds (e.g. small alcohols) into the headspace. Second, a linear relationship between injection volume, speed and temperature, and fecal sample mass on the abundance of VOC was demonstrated. Furthermore, the use of a septum preserved 90% of the non-polar compounds. By application of optimal instrumental and sampling conditions, a maximum of 320 unique compounds consisting of 14 different chemical classes could be detected. Conclusions These findings may contribute to standardized analysis of fecal VOC by HS-GC–MS, facilitating future application of fecal VOC in clinical practice.

Effects of Briquettes with Different Crack Structures on Propagation Characteristics of Ultrasonic Waves under Wetting Conditions

In order to examine the effect of briquettes with different crack structures on ultrasonic characteristics under different wetting conditions, a series of ultrasonic testing are carried out on briquettes at different wetting heights and the ultrasonic characteristics in these coal samples are explored. The results show that ultrasonic amplitude is positively correlated with the emission voltage, whereas ultrasonic frequency is negatively correlated with the emission voltage. Changes in both are closely related to the particle size and density. The ultrasonic velocity is positively correlated with the wetting degree. Sample mass has the greatest effect on the ultrasonic velocity, followed by particle size, and pressure has the smallest effect. At dry stage, ultrasonic velocity in gas coal is less than that in bituminous coal. The opposite is true in the fully wet state. The influence of crack thickness on ultrasonic velocity gradually increases with the wetting degree increasing. At dry stage, the velocity gradually increases with the crack dip increasing, while as the wetting height increasing, magnitude of velocity increase gradually decreases with the dip increasing. The ultrasonic attenuation in the briquettes reduces with the emission voltage enhancing. The attenuation decreases with sample particle size, crack thickness and crack size decreasing and with sample mass, pressure and crack dip increasing. The ultrasonic attenuation shows a trend of increase before decrease with the wetting height increasing. The attenuation of ultrasonic wave increases with wave velocity increasing for intact samples and shows a trend of increase before decrease for cracked samples.

Sample Mass Estimate for the Use of Near-Infrared and Raman Spectroscopy to Monitor Content Uniformity in a Tablet Press Feed Frame of a Drug Product Continuous Manufacturing Process

Recently, feed frame-based process analytical technology measurements used to assure product quality during continuous manufacturing processes have received significant attention. These measurements are able to accurately determine uniformity of the powder blend before compression, and in these applications, it is necessary to understand the interrogated sample volume per measurement. This understanding ensures that the blend measurement can be indicative of the uniformity of the final dosage form. A scientifically sound approach is proposed here to estimate sample mass for a continuous manufacturing process that utilizes either near infrared or Raman spectroscopy. A wide range of commercially available probes with varying spot diameters are considered. By comparing near infrared and Raman spectroscopy, an optimal range of probe spot diameters was identified in order to reach an estimated sample mass between 50 and 500 mg for pharmaceutical blends per measurement, which is equivalent to common tablet weight ranges for solid oral dosage forms currently on the market.

Nuclear Material Measurement Based on Fast Neutron Multiplicity Counter

Fast neutron multiplicity counting (FNMC) analysis method, as a new non-destructive analysis method for nuclear materials, plays an increasingly important role in the measurement of nuclear material properties. Based on the derivation of the FNMC analytical equation of Pu material, the method of solving the sample parameters was given. By analyzing the mechanism of interaction of neutrons and matter, the model used by Geant4 (version 10.4) software was determined, and a set of three-layer, fast neutron multiplicity counters with six liquid scintillation detectors per layer was constructed. Using the fast neutron multiplicity counter to analyze the measured parameters, the detection efficiency variation was less than 0.4% within the 150g sample mass range, and the PuO2 fluctuation was less than the metal Pu. By studying the detection efficiency and the multiplicity counting rate as a function of sample mass, within the 150g sample mass range, both basically meet the model assumptions of the FNMC analytical equation. The metal Pu and PuO2 samples were set separately, and the FNMC analysis equation was solved. When the sample mass was within 150g, the sample mass solution deviation was less than 10%. The results show that the built-in fast neutron multiplicity counter can better measure Pu sample properties.