Hyperoxemia Is Associated With Mortality in Critically Ill Children

Multiple studies among adults have suggested a non-linear relationship between arterial partial pressure of oxygen (PaO2) and clinical outcomes. Meta-analyses in this population suggest that high levels of supplemental oxygen resulting in hyperoxia are associated with mortality. This mini-review focuses on the non-neonatal pediatric literature examining the relationship between PaO2 and mortality. While only one pilot pediatric randomized-controlled trials exists, over the past decade, there have been at least eleven observational studies examining the relationship between PaO2 values and mortality in critically ill children. These analyses of mixed-case pediatric ICU populations have generally reported a parabolic (“u-shaped”) relationship between PaO2 and mortality, similar to that seen in the adult literature. However, the estimates of the point at which hyperoxemia becomes deleterious have varied widely (300–550 mmHg). Where attempted, this effect has been robust to analyses restricted to the first PaO2 value obtained, those obtained within 24 h of admission, anytime during admission, and the number of hyperoxemic blood gases over time. These findings have also been noted when using various methods of risk-adjustment (accounting for severity of illness scores or complex chronic conditions). Similar relationships were found in the majority of studies restricted to patients undergoing care after cardiac arrest. Taken together, the majority of the literature suggests that there is a robust parabolic relationship between PaO2 and risk-adjusted pediatric ICU mortality, but that the exact threshold at which hyperoxemia becomes deleterious is unclear, and likely beyond the typical target value for most clinical indications. Findings suggest that clinicians should remain judicious and thoughtful in the use of supplemental oxygen therapy in critically ill children.

Kinetics of Growth of Gas-Saturated (Embrittled) Layers on Titanium during Vacuum Annealing

The influence of the parameters of the vacuum annealing mode on the thickness of the embrittled layers, formed on the surface of titanium as a result of its interaction with the residual gases of the vacuumed space, is studied. The thickness and structure of the layers were determined on samples made of VT6 alloy obtained from sheet metal with a thickness of 3 mm. Annealing of samples in the temperature range of 500-750 °C was performed with air dilution from 10 to 3∙10-2 PA. The dimensions of the embrittled layers were determined by measuring the zone of brittle crack propagation in the fracture of the samples, and measuring the distance between the surface cracks in the embrittled layers, formed during bending deformation. To quantify the effect of vacuum annealing modes of sheet titanium alloy VT6 on the depth of the embrittled part of the formed oxide layer, it is proposed to use a parabolic relationship, characterized by the degree of growth and the constant of the embrittled layer. By processing experimental data, the effect of annealing time, temperature, and air dilution on the growth kinetics of the embrittled layers was established. Based on the obtained kinetic regularities of the growth of the embrittled layers, nomograms are constructed, to determine the size of the embrittled layer formed at the heating stage at different speeds up to the specified annealing temperature.

Abstract 15810: Applying an LDL-C Threshold Based Approach to Identify Individuals With Familial Hypercholesterolemia

Background: Familial hypercholesterolemia (FH) is an inherited disorder associated with increased LDL-C and premature coronary heart disease, which remains significantly underdiagnosed. Screening those with very high LDL-C may help identify those with FH, but the optimal means of applying this approach is unclear. Methods: Individuals from UT Southwestern Medical Center, a large, tertiary academic center, with an LDL-C level ≥ 190 mg/dL at any time were enrolled in an FH registry. These 5,786 patients were divided into four categories of LDL-C: 190.0 - 219.9, 220.0 - 249.9, 250.0 - 299.9, and ≥ 300.0 mg/dL. One hundred individuals were randomly selected from each category for manual chart review to determine 1) the presence of secondary causes of dyslipidemia (obstructive liver disease, nephrotic syndrome, hypothyroidism, specific medication use, other secondary cause) and 2) diagnosis of possible/definite FH by modified Simon Broome criteria and 3) probable/definite FH by modified Dutch Lipid Clinic Network (DLCN) criteria. Results: Of the 400 individuals with an LDL-C level ≥ 190 mg/dL (mean age 52 years ± 14) in this cohort, the presence of secondary causes increased across each LDL-C category ( p < 0.001) (Figure) with the greatest prevalence in those ≥ 300.0 mg/dL (52%). The prevalence of FH also varied by LDL-C category, with the highest prevalence of FH by Simon Broome criteria in the 220.0 - 249.9 mg/dL category (52%) and by DLCN criteria in the 250.0 - 299.9 mg/dL category (46%). Conclusions: Amongst those with LDL-C ≥ 190 mg/dL, the prevalence of secondary causes increases with higher LDL-C, while the diagnosis of FH has a parabolic relationship. Patients with intermediate LDL-C (220 - 299 mg/dL) may be the optimal group to prioritize for FH screening using an LDL-C based approach.

Dynamic stab resistance of multi-ply three-dimensional warp interlock fabrics with high-performance high-molecular-weight polyethylene yarns for protective applications

Fabrics constructed from 3 D warp interlock fabrics (3DWIFs) structures provide varying flexibility and durability and are promising structures for protective applications. However, its performance toward stab resistance from knife attack should be investigated before applying. In this work, the influences of fabric architectures, ply orientation of stacking sequences, and the number of fabric plies on the dynamic stab resistance are comparatively studied on high-molecular-weight polyethylene (HMWPE) 3DWIFs. It indicates that 3DWIF with orthogonal and through-the-thickness interlock structure reveals a helpful influence on stab resistance. Further investigation on the influence of different ply orientation of stacking sequences, based on the combination of fabrics placed at different angles, is analyzed showing a certain influence of stab resistance. Dynamic stab resistance reveals the linear correlation with a low number of fabric plies (less than 6 plies), but shows a parabolic relationship with the increase of fabric plies (more than 16 plies) until there is no penetration.

A Qualitative Study of the Critical Conditions for the Initiation of Mine Waste Debris Flows

Mine waste debris flows are a type of man-made debris flow that commonly lead to major disasters. In this study, the Xiaotong Gully, which is located in the Xiaoqinling gold mining area in China and contains a typical mine waste debris flow gully, was selected as the study area. Since a debris flow can be classified as either a geotechnical debris flow or hydraulic debris flow based on its initiation mode, we conducted 46 experimental model tests to explore the initiation conditions of these two different types of debris flows. According to our tests, the initiation conditions of hydraulic debris flows were mainly affected by the flume gradient, the water content of the mine waste, the inflow discharge, the water supply modes, and the clay particle content. A larger flume gradient and higher mine waste water content were more conducive to initiating a hydraulic debris flow. However, the influence of the water supply mode on the initiation of a hydraulic debris flow was complex (influenced by factors such as water content of mine waste, runoff discharge rate and rainfall intensity). The critical runoff of a hydraulic debris flow, which starts with a parabolic relationship to the clay particle content of the mine waste, decreased with increasing clay particle content and then increased. There was a minimum critical runoff when the clay content of the mine waste was 30%. The initiation conditions of a geotechnical debris flow were mainly affected by the flume gradient, the water content, and the clay particle content. The critical gradient of a geotechnical debris flow decreased with increasing water content and had a parabolic relationship to the clay particle content. In tests 31–46 of this study, the second and third critical slopes both decreased and then increased with increasing clay particle content. These preliminary research results provide a scientific reference for subsequent research on the prevention and mitigation of mine waste debris flows.

Raindrop Energy Impact on the Distribution Characteristics of Splash Aggregates of Cultivated Dark Loessial Cores

To determine the effect of different rainfall energy levels on the breakdown of soil aggregates, this study analyzed the soil splash erosion amounts and the distribution of particle sizes under six rainfall conditions (rainfall energy: 2.41 × 10−5–22.4 × 10−5 J m−2 s−1 and 1.29 × 10−4 J m−2 s−1) at five splash distances (from 0–10 cm to 40–50 cm). Cores of the size 10 × 20 cm of undisturbed cultivated dark loessial soil were selected in tree replicates as the research subject. The results indicated that splashed aggregates were distributed mainly at splash distances of 0–20 cm, which accounted for 66%–90% of the total splash erosion amount. The splash erosion amount significantly decreased exponentially with increasing splash distance for the same rainfall energy (p < 0.01). The splash erosion amount significantly increased in the power function relationship with increasing rainfall energy at the same splash distance (p < 0.05). A model was obtained to predict the splash erosion amount for rainfall energy and splash distance. The fractal dimension (D) of the aggregates showed a downward opening parabolic relationship with raindrop energy. The maximal value of the rainfall energy was 1.286 × 10−4 J m−2 s−1, which broke the aggregates to the largest degree. Enrichment ratio (ER) values for fragments >2 mm were close to 0. A particle size of 0.25 mm was the critical particle level for splash erosion.

049 Lower stimulus contrast is associated with stronger multifocal visual evoked potential signals

IntroductionVisual evoked potentials (VEPs) are used to assess the visual system in neuro-ophthalmological diseases such as multiple sclerosis (MS). Axonal damage, and subsequent reduction of VEP amplitude, is considered central to the development of disability. To obtain the strongest signal possible, high contrast (HC) pattern-reversing checkboard stimuli are routinely used to induce cortical electrical potentials. Low contrast (LC) visual acuity assessment is better than HC visual acuity testing in detecting MS-related visual impairment. This study aims to determine if the use of LC stimuli in multifocal VEPs improves detection visual dysfunction in patients with MS.Methods14 MS patients (8 with history of optic neuritis) and 12 healthy controls had HC (Michelson 98%) and LC (Michelson 22%) multifocal VEP performed. The VEP signal from the 56 individual sectors was transformed into absolute values and averaged. The area under the curve (AUC) for each individual’s mfVEP was determined for HC and LC stimuli. Subsequently, 5 healthy controls with best-corrected vision ≥20/20 underwent mfVEP assessment at 8 different contrast levels (Michelson contrast 8%, 15%, 22%–31% 41%, 53%, 64%, 98%).ResultsThere was no significant difference in the mfVEP AUC between MS patients (including 10 ON eyes only) and controls for HC, LC or the difference between HC and LC stimuli. Part 2 of the study demonstrated the relationship between stimulus contrast and signal strength. All subjects had a roughly parabolic relationship with AUC greatest at mid-level contrast. Averaged data of all subjects showed a parabolic relationship characterised by y=-2834.1x2 – 2127.1x+3144.2, R²=0.911.ConclusionAssessing reduction in mfVEP signal strength with LC stimuli requires an appropriate HC comparator stimulus. This study may also provide rationale for clinical mfVEP studies to use lower contrast stimuli to increase the signal strength of the study.

Effect of Molybdenum on the Microstructures of As-Cast Fe-B Alloys and Their Corrosion Resistance in Molten Zinc

The effect of Mo on the microstructure of as-cast Fe-3.5 B alloys and their corrosion behavior in molten zinc have been investigated. Experimental results show that the as-cast Fe-B alloys with molybdenum addition are mainly composed of α-Fe, Fe2B, FeMo2B2, and metastable Fe3B phases. Corrosion tests show that the Fe-3.5 B alloy with 8.0 wt% added molybdenum has the highest corrosion resistance in molten zinc mainly because the alloy still maintains the reticular structure of boride and improves its thermal stability. When the molybdenum content exceeds 8.0 wt%, the τ-FeMo2B2 + α-Fe eutectic microstructure destroys the reticular structure of the Fe2B phase, leading to reduction in the corrosion resistance of the as-cast Fe-B alloys. Four kinds of corrosion products (δp, δk, ζ, and FeB) were found in the corrosion layers. The corrosion mechanism of Fe-3.5 B alloys with various added molybdenum contents includes the following processes: the preferential corrosion of α-(Fe, Mo), the formation of typical Fe-Zn compounds, the transformation of (Fe, Mo)3B and (Fe, Mo)2B into FeB, and the spalling of borides. The diffusion of molybdenum in the solid matrix cannot occur in the corrosion process. The corrosion depth of the corrosion layer did not follow a parabolic relationship strictly, maybe it caused by the spalling of the corrosion layer under the attack of the liquid zinc. The corrosion process is mainly controlled by the diffusion of liquid zinc atoms.

Polyurethane based finishing of cotton fabric for imparting multifunctional properties by using central composite design

Purpose The purpose of this study was to overcome discomfort associated with it, a resin finish was applied in conjunction with hydrophilic polyurethane. Design/methodology/approach The process variables included concentrations of polyurethane and resin finishes, and pH under central composite design (CCD). The fabric specimens were assessed for crease recovery angle (CRA), tensile strength and moisture management properties. Findings Some models were developed for prediction of CRA and overall moisture management capability (OMMC) of treated fabric. It was observed that polyurethane concentration showed a parabolic relationship with CRA and a direct relationship with OMMC, whereas resin concentration showed a parabolic relationship with CRA and an inverse relationship with OMMC. Increase in pH from acidic to alkaline resulted in a decrease in CRA but an increase in OMMC. The untreated specimen had the highest tensile strength, whereas the specimen treated with polyurethane showed the least tensile strength loss, and the one treated with resin showed the highest loss in tensile strength. Practical implications As the polyurethane-based finish is soft and hydrophilic, so it was expected that it would overcome the uncomfortable feature of durable press finish, and with its flexibility, the strength losses might reduce. Originality/value This is the first report about the investigation of effects of increasing flexibility of the cross-link by incorporating polyurethane compounds into a typical dimethylol dihydroxy ethylene urea durable press resin formulation.

Boriding of Binary Ni–Ti Shape Memory Alloys

Boriding of binary Ni–Ti shape memory alloys was carried out in a solid medium at 1273 K for 2, 4, 6, and 8 h using the powder pack method with proprietary Ekabor–Ni powders. Characterization of the boride layer formed on the surface of alloys was done by optical microscopy and scanning electron microscopy. The presence of boride, silicide, and borosilicide phases in the boride layers was confirmed by X-ray diffraction analysis. The thickness and microhardness of the boride layers increased with increasing boriding time. Hardness profiles showed a rapid decrease in hardness moving from the boride layer to the main structure. The high hardness of the boride layer was attributed mainly to the formation of TiB2. A parabolic relationship was observed between layer thickness and boriding time, and the growth rate constant for the boriding treatment was calculated as 0.62×10−8 cm2 s−1.