Effect of the Grain Boundary Thermal Expansion Coefficient on the Fracture Toughness in Silicon Nitride

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/65261/1/j.1151-2916.1995.tb08667.x.pd

Infrared evidence of a Slater metal-insulator transition in NaOsO3

The magnetically driven metal-insulator transition (MIT) was predicted by Slater in the fifties. Here a long-range antiferromagnetic (AF) order can open up a gap at the Brillouin electronic band boundary regardless of the Coulomb repulsion magnitude. However, while many low-dimensional organic conductors display evidence for an AF driven MIT, in three-dimensional (3D) systems the Slater MIT still remains elusive. We employ terahertz and infrared spectroscopy to investigate the MIT in the NaOsO3 3D antiferromagnet. From the optical conductivity analysis we find evidence for a continuous opening of the energy gap, whose temperature dependence can be well described in terms of a second order phase transition. The comparison between the experimental Drude spectral weight and the one calculated through Local Density Approximation (LDA) shows that electronic correlations play a limited role in the MIT. All the experimental evidence demonstrates that NaOsO3 is the first known 3D Slater insulator.Comment: 4 figure

Robust and Scalable Transmission of Arbitrary 3D Models over Wireless Networks

We describe transmission of 3D objects represented by texture and mesh over unreliable networks, extending our earlier work for regular mesh structure to arbitrary meshes and considering linear versus cubic interpolation. Our approach to arbitrary meshes considers stripification of the mesh and distributing nearby vertices into different packets, combined with a strategy that does not need texture or mesh packets to be retransmitted. Only the valence (connectivity) packets need to be retransmitted; however, storage of valence information requires only 10% space compared to vertices and even less compared to photorealistic texture. Thus, less than 5% of the packets may need to be retransmitted in the worst case to allow our algorithm to successfully reconstruct an acceptable object under severe packet loss. Even though packet loss during transmission has received limited research attention in the past, this topic is important for improving quality under lossy conditions created by shadowing and interference. Results showing the implementation of the proposed approach using linear, cubic, and Laplacian interpolation are described, and the mesh reconstruction strategy is compared with other methods

Structures of Darunavir-Resistant HIV‑1 Protease Mutant Reveal Atypical Binding of Darunavir to Wide Open Flaps

The molecular basis for high resistance to clinical inhibitors of HIV-1 protease (PR) was examined for the variant designated PRP51 that was selected for resistance to darunavir (DRV). High resolution crystal structures of PRP51 with the active site D25N mutation revealed a ligand-free form and an inhibitor-bound form showing a unique binding site and orientation for DRV. This inactivating mutation is known to increase the dimer dissociation constant and decrease DRV affinity of PR. The PRP51‑D25N dimers were in the open conformation with widely separated flaps, as reported for other highly resistant variants. PRP51‑D25N dimer bound two DRV molecules and showed larger separation of 8.7 Å between the closest atoms of the two flaps compared with 4.4 Å for the ligand-free structure of this mutant. The ligand-free structure, however, lacked van der Waals contacts between Ile50 and Pro81′ from the other subunit in the dimer, unlike the majority of PR structures. DRV is bound inside the active site cavity; however, the inhibitor is oriented almost perpendicular to its typical position and exhibits only 2 direct hydrogen bond and two water-mediated interactions with atoms of PRP51‑D25N compared with 11 hydrogen bond interactions seen for DRV bound in the typical position in wild-type enzyme. The atypical location of DRV may provide opportunities for design of novel inhibitors targeting the open conformation of PR drug-resistant mutants

Reconsultation, self-reported health status and costs following treatment at a musculoskeletal Clinical Assessment and Treatment Service (CATS): a 12-month prospective cohort study

Objectives To determine (1) reconsultation frequency, (2) change in self-reported health status, (3) baseline factors associated with reconsultation and change in health status and (4) associated healthcare costs and quality-adjusted life-years (QALYs), following assessment at a musculoskeletal Clinical and Assessment Treatment Service (CATS). Design Prospective cohort study. Setting Single musculoskeletal CATS at the primary–secondary care interface. Participants 2166 CATS attenders followed-up by postal questionnaires at 6 and 12 months and review of medical records. Outcome measures Primary outcome was consultation in primary care with the same musculoskeletal problem within 12 months. Secondary outcome measures were consultation at the CATS with the same musculoskeletal problem within 12 months, physical function and pain (Short Form-36), anxiety and depression (Hospital Anxiety and Depression Scale), time off work, healthcare costs and QALYs. Results Over 12 months, 507 (38%) reconsulted for the same problem in primary care and 345 (26%) at the CATS. Primary care reconsultation in the first 3 months was associated with baseline pain interference (relative risk ratio 5.33; 95% CI 3.23 to 8.80) and spinal pain (1.75; 1.09 to 2.82), and after 3–6 months with baseline assessment by a hospital specialist (2.06; 1.13 to 3.75). Small mean improvements were seen in physical function (1.88; 95% CI 1.44 to 2.32) and body pain (3.86; 3.38 to 4.34) at 6 months. Poor physical function at 6 months was associated with obesity, chronic pain and poor baseline physical function. Mean (SD) 6-month cost and QALYs per patient were £422.40 (660.11) and 0.257 (0.144), respectively. Conclusions While most patients are appropriate for a ‘one-stop shop’ model, those with troublesome, disabling pain and spinal pain commonly reconsult and have ongoing problems. Services should be configured to identify and address such clinical complexity

Prolonged exposure to bacterial toxins downregulated expression of toll-like receptors in mesenchymal stromal cell-derived osteoprogenitors

<p>Abstract</p> <p>Background</p> <p>Human mesenchymal stromal cells (MSCs, also known as mesenchymal stem cells) are multipotent cells with potential therapeutic value. Owing to their osteogenic capability, MSCs may be clinically applied for facilitating osseointegration in dental implants or orthopedic repair of bony defect. However, whether wound infection or oral microflora may interfere with the growth and osteogenic differentiation of human MSCs remains unknown. This study investigated whether proliferation and osteogenic differentiation of MSCs would be affected by potent gram-positive and gram-negative derived bacterial toxins commonly found in human settings.</p> <p>Results</p> <p>We selected lipopolysaccharide (LPS) from <it>Escherichia coli </it>and lipoteichoic acid (LTA) from <it>Streptococcus pyogenes </it>as our toxins of choice. Our findings showed both LPS and LTA did not affect MSC proliferation, but prolonged LPS challenge upregulated the osteogenic differentiation of MSCs, as assessed by alkaline phosphatase activity and calcium deposition. Because toll-like receptors (TLRs), in particularly TLR4 and TLR2, are important for the cellular responsiveness to LPS and LTA respectively, we evaluated their expression profiles serially from MSCs to osteoblasts by quantitative PCR. We found that during osteogenic differentiation, MSC-derived osteoprogenitors gradually expressed TLR2 and TLR4 by Day 12. But under prolonged incubation with LPS, MSC-derived osteoprogenitors had reduced TLR2 and TLR4 gene expression. This peculiar response to LPS suggests a possible adaptive mechanism when MSCs are subjected to continuous exposure with bacteria.</p> <p>Conclusion</p> <p>In conclusion, our findings support the potential of using human MSCs as a biological graft, even under a bacterial toxin-rich environment.</p

Low ABA concentration promotes root growth and hydrotropism through relief of ABA INSENSITIVE 1-mediated inhibition of plasma membrane H+-ATPase 2

[EN] The hab1-1abi1-2abi2-2pp2ca-1 quadruple mutant (Qabi2-2) seedlings lacking key negative regulators of ABA signaling, namely, clade A protein phosphatases type 2C (PP2Cs), show more apoplastic H+ efflux in roots and display an enhanced root growth under normal medium or water stress medium compared to the wild type. The presence of low ABA concentration (0.1 micromolar), inhibiting PP2C activity via monomeric ABA receptors, enhances root apoplastic H+ efflux and growth of the wild type, resembling the Qabi2-2 phenotype in normal medium. Qabi2-2 seedlings also demonstrate increased hydrotropism compared to the wild type in obliquely-oriented hydrotropic experimental system, and asymmetric H+ efflux in root elongation zone is crucial for root hydrotropism. Moreover, we reveal that Arabidopsis ABA-insensitive 1, a key PP2C in ABA signaling, interacts directly with the C terminus of Arabidopsis plasma membrane H+-dependent adenosine triphosphatase 2 (AHA2) and dephosphorylates its penultimate threonine residue (Thr(947)), whose dephosphorylation negatively regulates AHA2.We are grateful for grant support from the National Key R&D Program of China (2017YFE0118100 and 2018YFD02003025), National Natural Science Foundation of China (nos. 31600209, 31761130073, and 31872169), a Newton Advanced Fellowship (NSFC-RS: NA160430), Fujian Province Education Department Funding (JK2017015), and Research Grant of FAFU (KXGH17005). Work in the laboratory of P.L.R. was supported by the Ministerio de Ciencia, Innovacion y Universidades (MICIU), grant BIO2017-82503-R.Miao, R.; Yuan, W.; Wang, Y.; Garcia-Maquilon, I.; Dang, X.; Li, Y.; Zhang, J.... (2021). Low ABA concentration promotes root growth and hydrotropism through relief of ABA INSENSITIVE 1-mediated inhibition of plasma membrane H+-ATPase 2. Science Advances. 7(12):1-14. https://doi.org/10.1126/sciadv.abd411311471

Antibodies against Lysophosphatidic Acid Protect against Blast-Induced Ocular Injuries

Exposure to blast overpressure waves is implicated as the major cause of ocular injuries and resultant visual dysfunction in veterans involved in recent combat operations. No effective therapeutic strategies have been developed so far for blast-induced ocular dysfunction. Lysophosphatidic acid (LPA) is a bioactive phospholipid generated by activated platelets, astrocytes, choroidal plexus cells, and microglia and is reported to play major roles in stimulating inflammatory processes. The levels of LPA in the cerebrospinal fluid have been reported to increase acutely in patients with traumatic brain injury (TBI) as well as in a controlled cortical impact (CCI) TBI model in mice. In the present study, we have evaluated the efficacy of a single intravenous administration of a monoclonal LPA antibody (25 mg/kg) given at 1 h post-blast for protection against injuries to the retina and associated ocular dysfunctions. Our results show that a single 19 psi blast exposure significantly increased the levels of several species of LPA in blood plasma at 1 and 4 h post-blast. The anti-LPA antibody treatment significantly decreased glial cell activation and preserved neuronal cell morphology in the retina on day 8 after blast exposure. Optokinetic measurements indicated that anti-LPA antibody treatment significantly improved visual acuity in both eyes on days 2 and 6 post-blast exposure. Anti-LPA antibody treatment significantly increased rod photoreceptor and bipolar neuronal cell signaling in both eyes on day 7 post-blast exposure. These results suggest that blast exposure triggers release of LPAs, which play a major role promoting blast-induced ocular injuries, and that a single early administration of anti-LPA antibodies provides significant protection