A solvent-resistant thin-film composite nanofibrous membrane: high permeance, high rejection in virtue of high porosity and low tortuosity.

Multiple thickness Fe foils were ramp compressed over several nanoseconds to pressure conditions relevant to the Earth's core. Using wave-profile analysis, the sound speed and the stress-density response were determined to a peak longitudinal stress of 273 GPa. The measured stress-density states lie between shock compression and 300-K static data, and are consistent with relatively low temperatures being achieved in these experiments. Phase transitions generally display time-dependent material response and generate a growing shock. We demonstrate for the first time that a low-pressure phase transformation (a-Fe to e-Fe) can be overdriven by an initial steady shock to avoid both the time-dependent response and the growing shock that has previously limited ramp-wave-loading experiments. In addition, the initial steady shock pre-compresses the Fe and allows different thermodynamic compression paths to be explored.

Structured Abstract Objective Root resorption due to orthodontic tooth movement may adversely affect the root‐crown (R/C) ratios of permanent teeth, especially in patients with Short Root Anomaly (SRA), a poorly understood disorder affecting root development. Evaluation of SRA R/C ratios to normal dentition would facilitate diagnosis and orthodontic treatment planning. However, reference values are not available for all ethnicities. Our goal was to determine R/C ratios of permanent teeth and their relationship to gender and ethnicity. Setting/Sample A retrospective study of 333 patients (109 Caucasians, 112 African Americans and 112 Hispanics) from the University of Alabama at Birmingham School of Dentistry. Materials/Methods Root lengths and crown heights were measured from panoramic radiographs of 6241 teeth using modified Lind's method. A linear mixed model was used to compare the R/C ratios of teeth among subgroups (gender, ethnicity). Results The mean R/C ratios varied from 1.80 to 2.21 for the maxillary teeth and 1.83‐2.49 for the mandibular teeth. Gender differences in R/C ratios were found to be significant only for the lower central incisors (P < 0.05). Hispanics showed significantly lower ratios for most teeth compared to the other two groups (P < 0.05). There were significant differences in R/C ratios between African Americans and Caucasians in the upper lateral incisors, lower central incisors and lower first premolars (P < 0.05). Conclusion Our results suggest that ethnicity is an important factor in determining the R/C ratios of permanent teeth. Therefore, when diagnosing developmental conditions such as SRA, ethnic group‐specific reference values should be considered.

Polyacrylonitrile based porous hollow gel fibers were prepared from PAN hollow fibers by oxidation and subsequent alkaline treatment. Fourier-transform infrared (FTIR), X-ray diffraction, and scanning electron microscope (SEM) analyses showed that the PAN porous hollow gel fiber was a kind of amphoteric fiber due to the combination of cationic groups of pyridyl and anionic groups of carboxyl; after gelation the hollow channel and finger-like pores on the fiber walls were conserved. The effects of cyclization reaction degree, alkaline solution concentration, and alkaline treatment time on the mechanical properties or pH-sensitive behavior of the porous hollow gel fibers were investigated. The elongation/contraction behavior was studied in detail. It was found that the gel fiber exhibited a large swelling in an alkaline solution and contracting in an acid solution; the swelling change in length was above 90%; the responsive time of elongation/contraction was less than 20 s; the maximum contraction force was 20 N/cm 2 ; and pH-sensitivity was reversible.