EXPRESS: Determination of Elemental Composition in Soft Biological Tissue Using Laser Ablation Inductively Coupled Plasma Mass Spectrometry: Method Validation

Determination of elemental concentrations in biological tissue is fundamental to many environmental studies. Analytical methods typically used to quantify concentrations in such studies have minimum sample volumes that necessitate lethal or impactful collection of tissues. Laser-ablation inductively coupled mass spectrometry (LA-ICP-MS) has small sample-volume requirements and offers environmental practitioners an opportunity to employ low-impact sample-collection methods. Environmental applications of LA-ICP-MS are limited by the lack of validated methods, partly due to the need for dry samples and scarcity of matrix-matched certified reference materials (CRMs). This study validates an LA-ICP-MS method to determine concentrations of 30 elements in soft biological tissue (fish ovary and muscle). Small tissue samples (median: 0.48 grams (g); inter-quartile range: 0.30 g to 0.56 g wet weight) were dehydrated, powdered, compressed into pellets (weighing approximately 0.03 mg) and analysed using LA-ICP-MS alongside three matrix-matched CRMs. The method yielded concentration determinations for CRM elements that were typically accurate to within 30% of theoretical concentrations, and precise (relative standard deviation [RSD] <20%). These results were repeatable: accuracy rarely deviated from theoretical values by more than 20%, and precision rarely exceeded 33%. Determinations for biological samples were replicable irrespective of tissue (ovary or muscle). There was good linearity between analyte signal strength and theoretical concentration (median R2 ≥ 0.981 for all elements) across ranges typically encountered in environmental studies. Concentrations could not be consistently obtained (i.e., determined concentrations were typically below detection limits) for boron, vanadium, molybdenum, and cadmium in muscles, and arsenic in both ovaries and muscles; however, detection limits were sufficiently low for most environmental contexts. Further methodological refinement could include the incorporation of spiked standards to extend linear ranges, and fine-tuning instrument parameters to obtain smoother signal intensities for rare elements. The method presented promotes the use low-impact sample-collection methods while enabling high-quality determinations of elemental concentrations in biological tissues.

Peningkatan Nilai Impak Baja Hadfield Mn 12 Melalui Proses Perlakuan Panas Homogenisasi Bertahap

Hadfield manganese steel is the steel with a composition of 1.0-1.4% C and 10-14% Mn, where the C: Mn ratio is made at 1:10. In as-cast conditions, the steel has a structure of carbide (Fe, Mn) 3C at the grain boundary, formed during slow cooling in the sand mold. The carbide existence can cause brittle properties of the material and needs to be eliminated by a heat treatment process that is homogenization (or solution treatment). In this study, a stepped heat treatment process was carried out by giving preheating at temperatures below the austenitizing temperature of 600 oC and 700 oC. The austenitizing temperature is given lower than the conventional method which usually uses 1050 oC, wherein this study austenitizing heating was given at 980 oC. Rapid quenching is performed using water with agitation or stirring to ensure that the cooling rate is fast enough to generate a 100% austenite structure. The results achieved that the sample with a stepped heat treatment process with a preheating temperature of 600 oC and followed by austenitizing of 980 oC could perform finer austenite grains, with the highest impact value of 255 Joules. A fracture of the impact sample resulting very ductile behavior which can be seen that the impact sample is not completely broken.

Using Odds Ratios to Detect Differential Item Functioning

Differential item functioning (DIF) makes test scores incomparable and substantially threatens test validity. Although conventional approaches, such as the logistic regression (LR) and the Mantel–Haenszel (MH) methods, have worked well, they are vulnerable to high percentages of DIF items in a test and missing data. This study developed a simple but effective method to detect DIF using the odds ratio (OR) of two groups’ responses to a studied item. The OR method uses all available information from examinees’ responses, and it can eliminate the potential influence of bias in the total scores. Through a series of simulation studies in which the DIF pattern, impact, sample size (equal/unequal), purification procedure (with/without), percentages of DIF items, and proportions of missing data were manipulated, the performance of the OR method was evaluated and compared with the LR and MH methods. The results showed that the OR method without a purification procedure outperformed the LR and MH methods in controlling false positive rates and yielding high true positive rates when tests had a high percentage of DIF items favoring the same group. In addition, only the OR method was feasible when tests adopted the item matrix sampling design. The effectiveness of the OR method with an empirical example was illustrated.

Universal power law of the gravity wave manifestation in the AIM CIPS polar mesospheric cloud images

We aim to extract a universal law that governs the gravity wave manifestation in polar mesospheric clouds (PMCs). Gravity wave morphology and the clarity level of display vary throughout the wave population manifested by the PMC albedo data. Higher clarity refers to more distinct exhibition of the features, which often correspond to larger variances and a better-organized nature. A gravity wave tracking algorithm based on the continuous Morlet wavelet transform is applied to the PMC albedo data at 83 km altitude taken by the Aeronomy of Ice in the Mesosphere (AIM) Cloud Imaging and Particle Size (CIPS) instrument to obtain a large ensemble of the gravity wave detections. The horizontal wavelengths in the range of ∼ 20–60 km are the focus of the study. It shows that the albedo (wave) power statistically increases as the background gets brighter. We resample the wave detections to conform to a normal distribution to examine the wave morphology and display clarity beyond the cloud brightness impact. Sample cases are selected at the two tails and the peak of the normal distribution to represent the full set of wave detections. For these cases the albedo power spectra follow exponential decay toward smaller scales. The high-albedo-power category has the most rapid decay (i.e., exponent = −3.2) and corresponds to the most distinct wave display. The wave display becomes increasingly blurrier for the medium- and low-power categories, which hold the monotonically decreasing spectral exponents of −2.9 and −2.5, respectively. The majority of waves are straight waves whose clarity levels can collapse between the different brightness levels, but in the brighter background the wave signatures seem to exhibit mildly turbulent-like behavior.

Universal power law of the gravity wave manifestation in the AIM CIPS polar mesospheric cloud images

We aim to extract a universal law that governs the wave display throughout the gravity wave population. Wave display morphology and clarity level varies throughout the wave population manifested through the PMC albedo data. Higher clarity refers to more distinct exhibition of the features which often correspond to larger variances and better organized nature. A gravity wave tracking algorithm is applied to the PMC albedo data taken by the AIM Cloud Imaging and Particle Size (CIPS) instrument to obtain a large ensemble of the gravity wave detections. The horizontal wavelengths in the range of ~ 20–60 km are the focus of the study. It shows that the albedo CWT power statistically increases as the background gets brighter. We resample the wave detections to conform to a normal distribution to examine the wave morphology beyond the cloud brightness impact. Sample cases are selected at the two tails and the peak of the normal distribution to represent the full set of wave detections. For these cases the albedo CWT power spectra follow exponential decay toward smaller scales. The high albedo power category has the most rapid decay (i.e., exponent = −3.2) and corresponds to the most distinct wave display. The wave display becomes increasingly more blurry for the medium and low power categories that hold the spectral exponents of −2.9 and −2.5, respectively. The majority of waves are straight waves whose clarity levels can be collapsed irrespective of the brightness levels but in the brighter background the wave signatures seem to exhibit mildly turbulent-like behavior.

Highlighting the challenge of delayed overall survival (OS) curve separation in immunotherapy clinical trials.

3009 Background: Cancer immunotherapy holds great potential but can elicit delayed responses, unlike chemotherapy. A delay in the separation of OS curves (between the control and treatment arms) has led to difficulty in achieving adequate power for OS analysis (Hoos A, Ann Oncol. 2012). Since combining immunotherapies, such as an anti-CTLA4 and an anti-PD-1, may increase the percentage of subjects achieving durable responses (Curran MA, PNAS. 2010), we sought to determine how adding a complementary immunologic agent to the currently-approved ipilimumab would impact delay in OS curve separation. Arbitrarily assuming that treatment effect on OS was doubled, we determined how various delays in OS curve separation might impact sample sizes. Methods: We evaluated three dual-immunotherapy clinical trial scenarios in which the separation of OS curves either remained the same, decreased, or increased. Baseline OS estimates were from pivotal trial data for ipilimumab in melanoma (Robert C et al, NEJM. 2011). SAS PROC POWER with piecewise linear survival curve was then used to determine approximate corresponding sample sizes. Results: See Table. Conclusions: Demonstrating significance in order to gain regulatory approval is important for providing potentially life-saving medications. For trials evaluating dual-immunotherapies, despite doubling treatment effects, delays in OS curve separation of up to 6 months would require over 2700 subjects to reach statistical power. In an era where treatments are increasingly personalized, these numbers will be difficult to achieve, underscoring the importance of novel trial designs incorporating Bayesian hierarchical modeling, precompetitive collaborations, and/or the use of state-of-the-art predictive biomarkers. [Table: see text]

Investigation of Fracture Mechanism of Casing-Drilling Steels

The paper reports on an investigation of the fracture mechanism of both tensile and impact fracture in three types of casing-drilling steels. The results show that the tensile fracture surface of N80 steel includes fibrous zone, radiation area and shear lip zone, and those of both K55 and P110 steels include two zones; all the tensile fracture surfaces of three types of casing drilling steels show the ductile fracture mode, the ductile fracture mode indicated with dimples is observed on all zones; the impact fracture surface of the N80 steel possesses a combined quasi-cleavage and ductile fracture modes, a single fracture mode is observed on the fracture surface of both K55 and P110 steels, the K55 steel impact sample is fractured in a cleavage brittle manner, whereas the P110 steel impact sample is fractured in a dimpled ductile manner.