Partial characterization of extruded collagen tubes with varied material deposition and orientation based on rotation rate and linear draw speed

This study established protocols for extrusion of collagen tubes from an extruder made by the ZOKO Corporation of Czechoslovakia. Using a viscous collagen base material, collagen tubes can be formed with changes in rotation rates from 0 rpm to 260 rpm and linear draw speeds from 383 mm/min to 1270 mm/min with a constant extrusion rate of 50 cm2/min. These tubes, with further research and treatment, can be used for various medical applications including vascular implants and nerve conduits. Post-extrusion, chemical crosslinking of the collagen increased the cohesiveness and mechanical integrity of the tubes. Microscopic photographs confirmed higher orientation of the fibers on the surface with less orientation on the interior surface of the tube. The collagen tubing displayed high affinity for water and was able to change mass by at least 100%. The tube volume changes ranged from 80% to 123% with length changes from 8% to 13% depending on thickness of the tube and the applied rotation rate. The tensile properties supported the idea of collagen as a short fiber-reinforced material. The maximum tensile strength was attained with low to medium rotation rate and a medium thickness tube. There was increased modulus of the initial toe region and a decreased end region modulus as the rotation rate increased. Thermal analysis showed differences between the shapes of energy versus temperature curves when comparing the tubes which were normal and those which were dehydrated before testing. Distinct water peaks increased in range for nondehydrated and decreased for dehydrated tubes with increasing rotation rate. An exothermic region also appeared which was either some form of shrinkage or denaturing/degradation of the collagen molecules. The actual degradation of the material had a beginning range of temperatures from 250° C to 257° C which apparently increased with increasing rotation rate

A Comparison of Presolar Isotopic Signatures in Laboratory-Studied Primitive Solar System Materials and Comet 67P/Churyumov-Gerasimenko: New Insights from Light Elements, Halogens, and Noble Gases.

Comets are considered the most primitive planetary bodies in our Solar System. ESA's Rosetta mission to Jupiter family comet 67P/Churyumov-Gerasimenko (67P/CG) has provided a wealth of isotope data which expanded the existing data sets on isotopic compositions of comets considerably. In a previous paper (Hoppe et al. in Space Sci. Rev. 214:106, 2018) we reviewed the results for comet 67P/CG from the first four years of data reduction after arrival of Rosetta at the comet in August 2014 and discussed them in the context of respective meteorite data. Since then important new isotope data of several elements, among them the biogenic elements H, C, N, and O, for comet 67P/CG, the Tagish Lake meteorite, and C-type asteroid Ryugu became available which provide new insights into the formation conditions of small planetary bodies in the Solar System's earliest history. To complement the picture on comet 67P/CG and its context to other primitive Solar System materials, especially meteorites, that emerged from our previous paper, we review here the isotopic compositions of H, C, and N in various volatile molecules, of O in water and a suite of other molecules, of the halogens Cl and Br, and of the noble gas Kr in comet 67P/CG. Furthermore, we also review the H isotope data obtained in the refractory organics of the dust grains collected in the coma of 67P/CG. These data are compared with the respective meteoritic and Ryugu data and spectroscopic observations of other comets and extra-solar environments; Cl, Br, and Kr data are also evaluated in the context of a potential late supernova contribution, as suggested by the Si- and S-isotopic data of 67P/CG

Importance of extracolonic findings at IV contrast medium-enhanced CT colonography versus those at non-enhanced CT colonography

To compare the clinical importance of extracolonic findings at intravenous (IV) contrast-enhanced CT colonography versus those at non-enhanced CT colonography. IV contrast medium-enhanced (n=72) and non-enhanced (n=30) multidetector CT colonography was performed in 102 symptomatic patients followed by conventional colonoscopy on the same day. The impact of extracolonic findings on further work up and treatment was assessed by a review of patient records. Extracolonic findings were divided into two groups: either leading to further work up respectively having an impact on therapy or not. A total of 303 extracolonic findings were detected. Of those, 71% (215/303) were found on IV contrast-enhanced CT, and 29% (88/303) were found on non-enhanced CT colonography. The extracolonic findings in 25% (26/102) of all patients led to further work up or had an impact on therapy. Twenty-two of these patients underwent CT colonography with IV contrast enhancement, and four without. The percentage of extracolonic findings leading to further work up or having an impact on therapy was higher for IV contrast-enhanced (31%; 22/72) than for non-enhanced (13%; 4/30) CT scans (P=0.12). IV contrast-enhanced CT colonography produced more extracolonic findings than non-enhanced CT colonography. A substantially greater proportion of findings on IV contrast-enhanced CT colonography led to further work up and treatment than did non-enhanced CT colonograph

Detection of hepatic portal venous gas: its clinical impact and outcome

The clinical impact and outcome of a rare radiographic finding of hepatic portal venous gas (HPVG) as well as the effectiveness of computed tomography (CT), CT scanogram, and conventional radiography in the detection of HPVG were retrospectively analyzed. CT scans, CT scanogram, and plain film radiographs of 11 patients with HPVG were reviewed and compared with their medical records and surgical and pathology reports. Eight of the 11 patients underwent plain film radiographs 1day before or after the CT scan. HPVG was detected at CT in all 11 patients, on CT scanogram in three (3 of 11, 27.3%), and on plain films in one (one of eight, 12.5%). In nine of 11 patients (81.8%), CT revealed an associated pneumatosis intestinalis. In six of the 11 patients (54.6%), acute mesenteric ischemia was the underlying disease for HPVG. Seven patients (63.6%) underwent emergency exploratory laparotomy. The mortality rate for HPVG alone was 27.3% (3 of 11) and for HPVG related to mesenteric bowel disease 50% (three of six). Acute mesenteric ischemia is the most common cause of HPVG, which continues to have a predictably higher mortality. CT is superior to CT scanograms and radiographs in the detection of HPVG and its underlying diseases and, therefore, should be used as the primary diagnostic too

Effect of flushing and exogenous gonadotropin treatment on reproductive performance of estrus synchronized mature ewes

Call number: LD2668 .T4 1966 H798Master of Scienc

Isotopic Signatures of Supernova Nucleosynthesis in Presolar Silicon Carbide Grains of Type AB with Supersolar 14N/15N Ratios

We report high-resolution C, N, Al, Si, and S isotope data of 38 presolar SiC grains of type AB. Seventeen of these grains are of subtype AB1 (14N/15N < 440 = solar) and 20 of subtype AB2 (14N/15N ≥ 440), previously proposed to be mainly from supernovae (AB1) and J-type carbon stars (AB2), respectively. Our data are compatible with previously obtained isotope data of AB grains, except that 26Al/27Al ratios of AB1 grains span a narrower range. The data are compared with predictions from supernova models that consider H ingestion into the He shell during the pre-supernova phase. In these models a mixture of explosive H and He burning occurs at the bottom of the He shell during passage of the supernova shock, forming the so-called O/nova zone. Mixing matter from the O/nova zone with matter from the overlying He/C zone and the stellar envelope shows that the isotopic compositions and trends of both AB1 and AB2 grains can be matched within the model uncertainties. This demonstrates that supernovae should be considered as potential sources of AB2 grains, in addition to J-type carbon stars and born-again asymptotic giant branch stars, as previously proposed

A novel multiple-trauma CT-scanning protocol using patient repositioning

Emergency CT examination is considered to be a trade-off between a short scan time and the acceptance of artifacts. This study evaluates the influence of patient repositioning on artifacts and scan time. Eighty-three consecutive multiple-trauma patients were included in this prospective study. Patients were examined without repositioning (group 1, n=39) or with patient rotation to feet-first with arms raised for scanning the chest and abdomen/pelvis (group 2, n=44). The mean scan time was 21min in group 1 and 25min in group 2 (P=0.01). The mean repositioning time in group 2 was 8min. Significantly, more artifacts were observed in group 1 (with a repeated scan in 7%) than in group 2 (P=0.0001). This novel multiple- trauma CT-scanning protocol with patient repositioning achieves a higher image quality with significantly fewer artifacts than without repositioning but increases scan time slightl

Evidence for Radiogenic Sulfur-32 in Type AB Presolar Silicon Carbide Grains?

We report C, Si, and S isotope measurements on 34 presolar silicon carbide grains of Type AB, characterized by 12C/13C < 10. Nitrogen, Mg-Al-, and Ca-Ti-isotopic compositions were measured on a subset of these grains. Three grains show large 32S excesses, a signature that has been previously observed for grains from supernovae (SNe). Enrichments in 32S may be due to contributions from the Si/S zone and the result of S molecule chemistry in still unmixed SN ejecta or due to incorporation of radioactive 32Si from C-rich explosive He shell ejecta. However, a SN origin remains unlikely for the three AB grains considered here, because of missing evidence for 44Ti, relatively low 26Al/27Al ratios (a few times 10-3), and radiogenic 32S along with low 12C/13C ratios. Instead, we show that born-again asymptotic giant branch (AGB) stars that have undergone a very-late thermal pulse (VLTP), known to have low 12C/13C ratios and enhanced abundances of the light s-process elements, can produce 32Si, which makes such stars attractive sources for AB grains with 32S excesses. This lends support to the proposal that at least some AB grains originate from born-again AGB stars, although uncertainties in the born-again AGB star models and possible variations of initial S-isotopic compositions in the parent stars of AB grains make it difficult to draw a definitive conclusion.Comment: 18 pages, 4 figures, 1 table, Accepted for publication in the Astrophysical Journal Letter

Investigating Correlations of Automatically Extracted Multimodal Features and Lecture Video Quality

Ranking and recommendation of multimedia content such as videos is usually realized with respect to the relevance to a user query. However, for lecture videos and MOOCs (Massive Open Online Courses) it is not only required to retrieve relevant videos, but particularly to find lecture videos of high quality that facilitate learning, for instance, independent of the video's or speaker's popularity. Thus, metadata about a lecture video's quality are crucial features for learning contexts, e.g., lecture video recommendation in search as learning scenarios. In this paper, we investigate whether automatically extracted features are correlated to quality aspects of a video. A set of scholarly videos from a Mass Open Online Course (MOOC) is analyzed regarding audio, linguistic, and visual features. Furthermore, a set of cross-modal features is proposed which are derived by combining transcripts, audio, video, and slide content. A user study is conducted to investigate the correlations between the automatically collected features and human ratings of quality aspects of a lecture video. Finally, the impact of our features on the knowledge gain of the participants is discussed