82 research outputs found
The use of nanosensors for monitoring civil structures
Nano-sensors were tested to demonstrate whether nanotechnology could be obtained efficiently in the civil engineering field. The objective of the experiment was to reach a specific amount of resistance and electric conductivity produced by the sensors, which were later compared to other researches. The sensor was fabricated using carbon nanotubes (CNT) more specifically multi-walled carbon nanotubes (MWNT’s) as a conductive material and Polydimethylsiloxane (PDMS) as a polymer. Three samples were made with different CNT percentages. The material was then coated on a compact tension specimen and tested in tension. The results obtained were positive. The coating materials contained a good amount of resistance. Fabricated tube shaped coating materials were additionally tested on their ductility. The calculated electric conductivity correlated well when compared to other researches. Therefore, it was concluded that nano-sensors could be fabricated with the results obtained. However, to improve the main experiment conducted, a slightly more brittle compact tension specimen is recommended to obtain better and more accurate results
The incidence of ossified superior transverse scapular ligament during nerve transfer through posterior shoulder approach
Background: The purpose of this study was to assess the incidence and importance of bony bridge that covers the supra scapular notch during posterior approach to transfer accessory nerve to suprascapular nerve. Methods: Between 2010 and 2015, the frequency and importance of suprascapular bony bridge instead of transverse ligament was assessed among patients with brachial plexus injury candidate to shoulder function restoration by accessory to suprascapular nerve transfer through posterior approach. Results: Forty three patients, 41 male and 2 female, (mean age: 32.5 years, range 14 to 36) were included in this study. Five male patients (11.6) had a complete bony rim on the superior scapular notch. Suprascapular nerve release needed osteotomy of the bony bridge and related equipment. Conclusion: Although all previous cadaveric studies among different ethnic groups had reported the prevalence between 0.3 to 30 of suprascapular canal, this in vivo study showed the incidence of 11.6. Preoperative alertness about this variation could make the exploration and release of the suprascapular nerve easier and reduce the risk of nerve injury or failing to anatomize it. COPYRIGHT 2019 © BY THE ARCHIVES OF BONE AND JOINT SURGERY
A hysteresis model with dipole interaction: one more devil-staircase
Magnetic properties of 2D systems of magnetic nanoobjects (2D regular
lattices of the magnetic nanoparticles or magnetic nanostripes) are considered.
The analytical calculation of the hysteresis curve of the system with
interaction between nanoobjects is provided. It is shown that during the
magnetization reversal system passes through a number of metastable states. The
kinetic problem of the magnetization reversal was solved for three models. The
following results have been obtained. 1) For 1D system (T=0) with the
long-range interaction with the energy proportional to , the
staircase-like shape of the magnetization curve has self-similar character. The
nature of the steps is determined by interplay of the interparticle interaction
and coercivity of the single nanoparticle. 2) The influence of the thermal
fluctuations on the kinetic process was examined in the framework of the
nearest-neighbor interaction model. The thermal fluctuations lead to the
additional splitting of the steps on the magnetization curve. 3) The
magnetization curve for system with interaction and coercivity dispersion was
calculated in mean field approximation. The simple method to experimentally
distinguish the influence of interaction and coercivity dispersion on the
magnetization curve is suggested.Comment: 22 pages, 8 figure
The sample of choice for detecting Middle East respiratory syndrome coronavirus in asymptomatic dromedary camels using real-time reverse-transcription polymerase chain reaction
The newly identified Middle East respiratory syndrome coronavirus (MERS-CoV), which causes severe respiratory disease, particularly in people with comorbidities, requires further investigation. Studies in Qatar and elsewhere have provided evidence that dromedary camels are a reservoir for the virus, but the exact modes of transmission of MERS-CoV to humans remain unclear. In February 2014, an assessment was made of the suitability and sensitivity of different types of sample for the detection of MERS-CoV by real-time reverse-transcription polymerase chain reaction (RT-PCR) for three gene targets: UpE (upstream of the E gene), the N (nucleocapsid) gene and open reading frame (ORF) 1a. Fifty-three animals presented for slaughter were sampled. A high percentage of the sampled camels (79% [95% confidence interval 66.9-91.5%, standard error 0.0625]; 42 out of 53) were shown to be shedding MERS-CoV at the time of slaughter, yet all the animals were apparently healthy. Among the virus-positive animals, nasal swabs were most often positive (97.6%). Oral swabs were the second most frequently positive (35.7%), followed by rectal swabs (28.5%). In addition, the highest viral load, expressed as a cycle threshold (Ct) value of 11.27, was obtained from a nasal swab. These findings lead to the conclusion that nasal swabs are the candidate sample of choice for detecting MERS-CoV using RT-PCR technology in apparently healthy camels
The GPCR-gαs-PKA Signaling Axis Promotes T Cell Dysfunction and Cancer Immunotherapy Failure
Immune checkpoint blockade (ICB) targeting PD-1 and CTLA-4 has revolutionized cancer treatment. However, many cancers do not respond to ICB, prompting the search for additional strategies to achieve durable responses. G-protein-coupled receptors (GPCRs) are the most intensively studied drug targets but are underexplored in immuno-oncology. Here, we cross-integrated large singe-cell RNA-sequencing datasets from CD8+ T cells covering 19 distinct cancer types and identified an enrichment of Gαs-coupled GPCRs on exhausted CD8+ T cells. These include EP2, EP4, A2AR, β1AR and β2AR, all of which promote T cell dysfunction. We also developed transgenic mice expressing a chemogenetic CD8-restricted Gαs–DREADD to activate CD8-restricted Gαs signaling and show that a Gαs–PKA signaling axis promotes CD8+ T cell dysfunction and immunotherapy failure. These data indicate that Gαs–GPCRs are druggable immune checkpoints that might be targeted to enhance the response to ICB immunotherapies
Middle East respiratory syndrome coronavirus in dromedary camels: An outbreak investigation
Background: Middle East respiratory syndrome coronavirus (MERS-CoV) causes severe lower respiratory tract infection in people. Previous studies suggested dromedary camels were a reservoir for this virus. We tested for the presence of MERS-CoV in dromedary camels from a farm in Qatar linked to two human cases of the infection in October, 2013. Methods: We took nose swabs, rectal swabs, and blood samples from all camels on the Qatari farm. We tested swabs with RT-PCR, with amplification targeting the E gene (upE), nucleocapsid (N) gene, and open reading frame (ORF) 1a. PCR positive samples were tested by different MERS-CoV specific PCRs and obtained sequences were used for phylogentic analysis together with sequences from the linked human cases and other human cases. We tested serum samples from the camels for IgG immunofluorescence assay, protein microarray, and virus neutralisation assay. Findings: We obtained samples from 14 camels on Oct 17, 2013. We detected MERS-CoV in nose swabs from three camels by three independent RT-PCRs and sequencing. The nucleotide sequence of an ORF1a fragment (940 nucleotides) and a 4·2 kb concatenated fragment were very similar to the MERS-CoV from two human cases on the same farm and a MERS-CoV isolate from Hafr-Al-Batin. Eight additional camel nose swabs were positive on one or more RT-PCRs, but could not be confirmed by sequencing. All camels had MERS-CoV spike-binding antibodies that correlated well with the presence of neutralising antibodies to MERS-CoV. Interpretation: Our study provides virological confirmation of MERS-CoV in camels and suggests a recent outbreak affecting both human beings and camels. We cannot conclude whether the people on the farm were infected by the camels or vice versa, or if a third source was responsible. Funding: European Union projects EMPERIE (contract number 223498), ANTIGONE (contract number 278976), and the VIRGO consortium
Creating Physical 3D Stereolithograph Models of Brain and Skull
The human brain and skull are three dimensional (3D) anatomical structures with complex surfaces. However, medical images are often two dimensional (2D) and provide incomplete visualization of structural morphology. To overcome this loss in dimension, we developed and validated a freely available, semi-automated pathway to build 3D virtual reality (VR) and hand-held, stereolithograph models. To evaluate whether surface visualization in 3D was more informative than in 2D, undergraduate students (n = 50) used the Gillespie scale to rate 3D VR and physical models of both a living patient-volunteer's brain and the skull of Phineas Gage, a historically famous railroad worker whose misfortune with a projectile tamping iron provided the first evidence of a structure-function relationship in brain. Using our processing pathway, we successfully fabricated human brain and skull replicas and validated that the stereolithograph model preserved the scale of the VR model. Based on the Gillespie ratings, students indicated that the biological utility and quality of visual information at the surface of VR and stereolithograph models were greater than the 2D images from which they were derived. The method we developed is useful to create VR and stereolithograph 3D models from medical images and can be used to model hard or soft tissue in living or preserved specimens. Compared to 2D images, VR and stereolithograph models provide an extra dimension that enhances both the quality of visual information and utility of surface visualization in neuroscience and medicine
Comparative Proteomic Analysis of Methanothermobacter themautotrophicus ΔH in Pure Culture and in Co-Culture with a Butyrate-Oxidizing Bacterium
To understand the physiological basis of methanogenic archaea living on interspecies H2 transfer, the protein expression of a hydrogenotrophic methanogen, Methanothermobacter thermautotrophicus strain ΔH, was investigated in both pure culture and syntrophic coculture with an anaerobic butyrate oxidizer Syntrophothermus lipocalidus strain TGB-C1 as an H2 supplier. Comparative proteomic analysis showed that global protein expression of methanogen cells in the model coculture was substantially different from that of pure cultured cells. In brief, in syntrophic coculture, although methanogenesis-driven energy generation appeared to be maintained by shifting the pathway to the alternative methyl coenzyme M reductase isozyme I and cofactor F420-dependent process, the machinery proteins involved in carbon fixation, amino acid synthesis, and RNA/DNA metabolisms tended to be down-regulated, indicating restrained cell growth rather than vigorous proliferation. In addition, our proteome analysis revealed that α subunits of proteasome were differentially acetylated between the two culture conditions. Since the relevant modification has been suspected to regulate proteolytic activity of the proteasome, the global protein turnover rate could be controlled under syntrophic growth conditions. To our knowledge, the present study is the first report on N-acetylation of proteasome subunits in methanogenic archaea. These results clearly indicated that physiological adaptation of hydrogenotrophic methanogens to syntrophic growth is more complicated than that of hitherto proposed
Surgical management of dural arteriovenous fistulas with transosseous arterial feeders involving the jugular bulb
Dural arteriovenous fistulas located in the vicinity of the jugular foramen are complex vascular malformations and belong to the most challenging skull base lesions to treat. The authors comprehensively analyze multiple features in a series of dural arteriovenous fistulas with transosseous arterial feeders involving the jugular bulb. Four patients who underwent surgery via the transcondylar approach to treat dural arteriovenous fistulas around the jugular foramen were retrospectively reviewed. Previously, endovascular treatment was attempted in all patients. The success of the surgical treatment was examined with postoperative angiography. Complete obliteration of the dural arteriovenous fistulas (DAVFs) was achieved in three patients, and significant flow reduction in one individual. All patients had a good postoperative outcome, and only one experienced mild hypoglossal nerve palsy. Despite extensive bone drilling, an occipitocervical fusion was necessary in only one patient with bilateral lesions. The use of an individually tailored transcondylar approach to treat dural arteriovenous fistulas at the region of the jugular foramen is most effective. This approach allows for complete obliteration of the connecting arterial feeders, and removal of bony structures containing pathological vessels
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