Impact-Initiation Sensitivity of High-Temperature PTFE-Al-W Reactive Materials

Drop-weight tests were conducted to investigate the impact-initiation sensitivity of high-temperature PTFE-Al-W reactive materials. The test results show that the impact-initiation sensitivity of the materials more than doubles with increasing the sample temperature from 25 to 350 °C. Combined with the impact-induced initiation process recorded by high-speed video and the difference between reacted and unreacted residues, the crack-induced initiation mechanism was revealed. The rapid propagation of crack provides a high-temperature and aerobic environment where Al reacts violently to PTFE, which induces the initiation. Moreover, the influence of sample temperature on the sensitivity was discussed and analyzed. The analysis results indicate that the sensitivity shows a temperature interval effect, and 127 and 327 °C are the interval boundaries where the sensitivity changes significantly. The sensitivity may leaps at 127 °C and increases more rapidly in the temperature interval from 127 to 327 °C, but hardly changes after the temperature reaches 327 °C.

Bias Effects on g- and s-Factors in Westcott Convention

For accuracy improvement of neutron activation analysis and neutron capture cross sections, bias effects are investigated on g- and s-factors in the Westcott convention. As origins of biases, a joining function shape, neutron temperature, and sample temperature have been investigated. Biases are quantitatively deduced for two 1/v isotopes (197Au, 59Co) and six non-1/v isotopes (241Am, 151Eu, 103Rh, 115In, 177Hf, 226Ra). The s-factor calculated with a joining function deduced recently by a detailed Monte Carlo simulation is compared to s-factors calculated with traditional joining functions by Westcott. The results show the bias induced by the sample temperature is small, in the order of 0.1% for the g-factor and in the order of 1% for the s-factor. On the other hand, the bias size induced by a joining function shape for the s-factor depends significantly on both isotopes and neutron temperature. As a result, the reaction rates are also affected significantly. The bias size for the reaction rate is given in the case of an epithermal neutron index r = 0.1, for the eight isotopes.

Study on the Effect of Sample Temperature on the Uniaxial Compressive Mechanical Properties of the Brain Tissue

Craniocerebral injury has been a research focus in the field of injury biomechanics. Although experimental endeavors have made certain progress in characterizing the material behavior of the brain, the temperature dependency of brain mechanics appears to be inconclusive thus far. To partially address this knowledge gap, the current study measured the brain material behavior via unconstrained uniaxial compression tests under low strain rate (0.0083 s-1) and high strain rate (0.83 s-1) at four different sample temperatures (13°C, 20°C, 27°C, and 37°C). Each group has 9~12 samples. One-way analysis of variance method was used to study the influence of sample temperature on engineering stress. The results show that the effect of sample temperature on the mechanical properties of brain tissue is significant under the high strain rate, especially at low temperature (13°C), in which the hardening of the brain tissue is very obvious. At the low strain rate, no temperature dependency of brain mechanics is noted. Therefore, the current results highlight that the temperature of the brain sample should be ensured to be in accordance with the living subject when studying the biomechanical response of living tissue.

DESIGN OF EXPERIMENT (DOE) BASED STUDY OF FACTORS AFFECTING UV ABSORPTION OF HYDROCHLOROTHIAZIDE

Present work was carried out to evaluate the effect of process variables on the UV absorbance of hydrochlorothiazide. The effect of three variables namely such as sample temperature, nature of the solvent and sample volume on UV absorption was studied by using the design of experiments (DOE) approach. Central Composite Design (CCD) was applied to investigate the effect of sample temperature (A) variation in the range of 15 °C - 45 °C, nature of the solvent (B) viz. ethanol, methanol, and 4 % sodium hydroxide and sample volume (C) in the range of 1.5 mL to 2 mL on the UV absorbance of Hydrochlorothiazide. Each of the parameters was varied at three different levels (-1, 0, 1) and twenty suggested experimental runs were conducted with six central points. The data was then analyzed for model fitting and finding how each of the variables affected the response by using ANOVA. The three variables under study were found to have a moderate effect on the UV absorbance, as expected based on theoretical concepts. However, the influence was found to be statistically insignificant as the P value for the individual parameter was found to be greater than 0.05. Further, the P value was less than 0.05 for the squares of temperature, solvent, and combination of solvent and volume for UV absorbance of hydrochlorothiazide, implying that these factors have a statistically significant bearing on UV absorbance. Results showed that out of the three parameters under study, the temperature of the sample affected the absorbance of hydrochlorothiazide the most.

Reliability of Three Urine Specific Gravity Meters Measuring Brix and Urine Solutions at Different Temperatures

Context: The measurement of urine specific gravity should be performed at room temperature (20 °C) but sample temperature is not always taken in consideration. Objective: Evaluate the effect of sample temperature on the measurement accuracy of a digital (DIG) and optical (MAN) refractometer and a hydrometer (HYD). Design: Quantitative comparison between measurement outcomes for a reference solution (sucrose, degrees Brix) and fresh collected urine samples. Samples: Experiment 1 used a 24 Brix (°Bx) samples and experiment 2 used 33 fresh urine samples. Main Outcome Measure: Urine specific gravity (USG). Results: Experiment 1 showed DIG and MAN did not differ from reference, but HYD reported lower or inconsistent values compared to Bx, while highly correlating with Bx solutions (r: > 0.89). The overall diagnostic ability of elevated USG (≥ 1.020; ≥ 1.025; ≥ 1.030) was high for all tools (AUC > 0.92). Misclassification of samples increased from 0 to 2 at 1.020 to 1 to 3 samples at cutoff 1.025 and 1.030 USG. Bland–Altman analysis showed DIG 5 °C underreports slightly without reporting bias (r: −0.344, P = 0.13); all other plots for DIG, MAN, and HYD showed considerably larger underreporting at higher concentrations (r ranging from −0.21 to −0.97 with P > .02) at all temperatures. The outcomes of experiment 2 using DIG 20°C as standard, showed only negligible differences between DIG and MAN at all temperatures, but larger differences using HYD. Conclusions: All tools showed reporting bias when compared to °Bx solutions which can impact classification of low and high urine concentration at higher USG cutoff values, especially at a sample temperature of 37 °C.

A scanning quantum cryogenic atom microscope at 6 K

The Scanning Quantum Cryogenic Atom Microscope (SQCRAMscope) is a quantum sensor in which a quasi-1D quantum gas images electromagnetic fields emitted from a nearby sample. We report improvements to the microscope. Cryogen usage is reduced by replacing the liquid cryostat with a closed-cycle system and modified cold finger, and cryogenic cooling is enhanced by adding a radiation shield. The minimum accessible sample temperature is reduced from 35~K to 5.7~K while maintaining low sample vibrations. A new sample mount is easier to exchange, and quantum gas preparation is streamlined.