Thermo Sensitivity of Polysiloxane/Silica Nanocomposites Affected by the Structure of Polymer-Filler Interface.

In this work thermo sensitivity was investigated with the bound rubber theory and thermoelasticity theory of the polymer-filler interface interaction between Polymethylvinylsiloxane (PMVS) and nanofillers (fumed and precipitated silica with the primary particle size of 10 nanometres). Bound rubber (the transition phase between PMVS and silica) content was measured by sol-gel analysis and swelling experiments. Results showed that the amount of bound rubber increases steadily with the increases of filler content. But the increasing rate suddenly decreased at certain silica content (between 40 and 50 phr of precipitated silica and between 30 and 40 phr of fumed silica, respectively), which was constant with the thermoelaticity experiment results. The temperature coefficients in low strain uniaxial extension are found to present sudden changing at the same silica content. This observation shows that thermo sensitivity is closely connected with the structure of polymer-filler interface.

Quantitative Study on Reinforcing Mechanism of Nanofiller Network in Silicone Elastomer Based on Fluorescence Labeling Technology.

Although there have been many theoretical studies on the enhancement effect of nanofiller networks and their interaction with elastomer molecular chains on the mechanical properties of elastomers, its mechanism description is still not completely clear. One of the main obstacles is the lack of quantitative characterization techniques and corresponding theoretical models for the three-dimensional morphology of complex nanofiller networks. In this paper, the precipitated silica-filled silicone rubber was studied by fluorescence labeling combined with laser scanning confocal microscopy, and the real three-dimensional images of dispersion and aggregation structure of filled rubber systems were obtained. The microstructure evolution of nano-particle aggregates caused by the increase in the filler volume fraction was quantitatively described, and the reinforcement mechanism of elastomers with a distribution of aggregates and filler networks composed of nanoparticles was studied. Furthermore, a nano-composite reinforcement model based on volume fraction, particle shape, interaction, and filler dispersion has been proposed.

Performance Enhancement of Silicone Rubber Using Superhydrophobic Silica Aerogel with Robust Nanonetwork Structure and Outstanding Interfacial Effect.

The application of high-performance rubber nanocomposites has attracted wide attention, but its development is limited by the imbalance of interface and network effects caused by fillers. Herein, an ultrastrong polymer nanocomposite is successfully designed by introducing a superhydrophobic and mesoporous silica aerogel (HSA) as the filler to poly(methyl vinyl phenyl) siloxane (PVMQ), which increased the PVMQ elongation at break (∼690.1%) by ∼9.3 times and the strength at break (∼6.6 MPa) by ∼24.3 times. Furthermore, HSA/PVMQ with a high dynamic storage modulus (G'0) of ∼12.2 MPa and high Payne effect (ΔG') of ∼9.4 MPa is simultaneously achieved, which is equivalent to 2-3 times that of commercial fumed silica reinforced PVMQ. The superior performance is attributed to the filler-rubber interfacial interaction and the robust filler-rubber entanglement network which is observed by scanning electron microscopy. When the HSA-PVMQ entanglement network is subjected to external stress, both the HSA and bound-PVMQ chains are synergistically involved in resisting structural evolution, resulting in the maximized energy dissipation and deformation resistance through the desorption of the polymer chain and the slip/interpenetrating of the exchange hydrogen bond pairs. Hence, highly aggregated nanoporous silica aerogels may soon be widely used in the application of reinforced silicone rubber or other polymers shortly.

Comparison of four nutritional screening tools in perioperative elderly patients: Taking orthopedic and neurosurgical patients as examples.

Background and aims: Malnutrition is widely present in elderly surgical patients and is highly correlated with prognosis after surgery. However, studies comparing the effectiveness of comprehensive nutritional screening tools in geriatric surgical patients have not yet been published. The nutritional risk among elderly orthopedic and neurosurgical patients and their associated clinical indicators and outcomes was assessed using four screening tools. The aim of this study was to explore suitable tools for screening the nutritional status and identify their potential to act as prognostic indicators. Methods: The Nutritional Risk Score 2002 (NRS2002), Mini Nutritional Assessment - Short Form (MNA-SF), Geriatric Nutritional Risk Index (GNRI), and Prognostic Nutritional Index (PNI) were all performed within two days of admission and before surgery. The relationships between nutritional risk classifications and conventional nutritional markers, complications and length of hospital stay (LOS) were evaluated. Results: In this study, a total of 167 orthopedic patients and 103 neurosurgical patients were evaluated. In neurosurgical patients, the rates of malnutrition or patients at risk of malnutrition according to the MNA-SF, GNRI, NRS2002 and PNI were 26.4, 24.6, 8.4, and 12.6%, respectively. According to the NRS2002 and PNI, the rates of old neurosurgical patients who were malnourished or at risk of malnutrition were 14.6 and 3.9%, respectively, which were lower than the results assessed by the MNA-SF (24.3%) and GNRI (15.5%). Multiple regression analysis revealed a significant relationship between the PNI (malnourished vs.well-nourished, OR = 5.39, 95% CI:1.11-26.18, P = 0.037), GNRI (at risk vs.no risk, OR = 3.96, 95% CI: 1.01-15.45, P = 0.048) and the complications in orthopedic patients. Only GNRI was significantly related to LOS > 7 days (at risk vs.no risk, OR = 4.01, 95% CI: 1.64-9.80, P = 0.002). For neurosurgical patients, an association between GNRI and LOS > 8 days was discovered (at risk vs.no risk, OR = 3.35, 95% CI: 1.03-10.86, P = 0.002). Conclusion: Among the four nutritional risk screening tools, the GNRI exhibited better predictive value for short-term outcomes in elderly perioperative orthopedic and neurosurgical patients, thereby suggesting that it might be a more suitable tool for nutritional risk screening. Additional studies are required to determine the applicability of GNRI in other surgical fields.

Localization of Chicken Rab22a in Cells and Its Relationship to BF or Ii Molecules and Genes.

Rab22a is an important small GTPase protein the molecule that is involved in intracellular transportation and regulation of proteins. It also plays an important role in antigens uptake, transportation, regulation of endosome morphology, and also regulates the transport of antigens to MHC (Major Histocompatibility Complex) molecules. To investigate the role of Rab22a, the intracellular co-localization of chicken Rab22a (cRab22a) molecule and its relationship to BF and chicken invariant chain (cIi) molecules was studied. A 3D protein structure of Rab22a was constructed by using informatics tools (DNASTAR 4.0 and DNAMAN). Based on the model, the corresponding recombinant eukaryotic plasmids were constructed by point mutations in the protein's structural domains. HEK 293T cells were co-transfected with plasmids pEGFP-C1-cIi to observe the intracellular co-localization. Secondly, the DC2.4 Mouse Dendritic Cell and Murine RAW 264.7 cells were transfected with recombinant plasmids of pmCherry-cRab22a and pmCherry-mRab22a respectively. Subsequently, the intracellular localization of cRab22a in early and late endosomes was observed with specific antibodies against EEA1 and LAMP1 respectively. For gene expression-based studies, the cRab22a gene was down-regulated and up-regulated in HD11 cells, following the detection of transcription levels of the BFa (MHCIa) and cIi genes by real-time quantitative PCR (RT-qPCR). The interactions of the cRab22a gene with BFa and cIi were detected by co-immunoprecipitation (Co-IP) and Western blot. The results showed that the protein structures of chicken and mouse Rab22a were highly homologous (95.4%), and both localize to the early and late endosomes. Ser41 and Tyr74 are key amino acids in the Switch regions of Rab22a which maintain its intracellular localization. The down-regulation of cRab22a gene expression significantly reduced (p < 0.01) the transcription of BFa (MHCIa) and cIi in HD11 cells. However, when the expression of the cRab22a gene was increased 55 times as compared to control cells, the expression of the BFa (MHCIa) gene was increased 1.7 times compared to the control cells (p < 0.01), while the expression of the cIi gene did not significantly differ from control (p > 0.05). Western blot results showed that cRab22a could not directly bind to BFa and cIi. So, cRab22a can regulate BFa and cIi protein molecules indirectly. It is concluded that cRab22a was localized with cIi in the endosome. The Switch regions of cRab22a are the key domains that affect intracellular localization and colocalization of the cIi molecule.

Studying Complex Evolution of Hyperelastic Materials under External Field Stimuli using Artificial Neural Networks with Spatiotemporal Features in a Small-Scale Dataset.

Deep-learning (DL) methods, in consideration of their excellence in dealing with highly complex structure-performance relationships for materials, are expected to become a new design paradigm for breakthroughs in material performance. However, in most cases, it is impractical to collect massive-scale experimental data or open-source theoretical databases to support training DL models with sufficient prediction accuracy. In a dataset consisting of 483 porous silicone rubber observations generated via ink-writing additive manufacturing, this work demonstrates that constructing low-dimensional, accurate descriptors is the prerequisite for obtaining high-precision DL models based on small experimental datasets. On this basis, a unique convolutional bidirectional long short-term memory model with spatiotemporal features extraction capability is designed, whose hierarchical learning mechanism further reduces the requirement for the amount of data by taking full advantage of data information. The proposed approach can be expected as a powerful tool for innovative material design on small experimental datasets, which can also be used to explore the evolutionary mechanisms of the structures and properties of materials under complex working conditions.

Structure and Properties of La(2)O(3)-TiO(2) Nanocomposite Films for Biomedical Applications.

The hemocompatibility of La(2)O(3)-doped TiO(2) films with different concentration prepared by radio frequency (RF) sputtering was studied. The microstructures and blood compatibility of TiO(2) films were investigated by scan electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and UV-visible optical absorption spectroscopy, respectively. With the increasing of the La(2)O(3) concentrations, the TiO(2) films become smooth, and the grain size becomes smaller. Meanwhile, the band gap of the samples increases from 2.85 to 3.3 eV with increasing of the La(2)O(3) content in TiO(2) films from 0 to 3.64%. La(2)O(3)-doped TiO(2) films exhibit n-type semiconductor properties due to the existence of Ti(2+) and Ti(3+). The mechanism of hemocompatibility of TiO(2) film doped with La(2)O(3) was analyzed and discussed.

The fowl adenovirus serotype 4 (FAdV-4) induce cellular pathway in chickens to produce interferon and antigen-presented molecules (MHCI/II).

FAdV-4 is the major strain of adenovirus that responsible for hydro-pericardial syndrome (HPS) in poultry. In this study, the virus's specific gene fragments were isolated from clinically suspected cases and amplified by PCR. Finally, after a viral infection to investigate the immune response of the host, the gene expression of MHC (major histo-compatible) molecules (MHCIα, MHCIIß), Ii (Invariant Chain) gene, inflammatory cytokines (IFN-ß, IFN-γ, and IL-1ß), and transcription factors (MDA5, STING, IRF7, and NF-kB) were detected by real-time PCR (fluorescence technology). The results of sequence comparison showed that the clinically isolated virus was 100% homologous to a virulent strain of avian adenovirus group C serotype 4 (FAdV-4), which were named AH-FAdV-4. The TCID50 and pathogenicity of the virus were determined that was 106.52/0.1 mL with a mortality rate of 100% in chickens and 0% in ducks. Furthermore, results showed that the expression level of MHCIα, MHCIIß, and Ii genes in chicken embryo kidney cells significantly (P < 0.01) upregulated (increased) after infection, which was 43, 5.2, and 2.5 times higher than the control group. With the addition of PDTC, an inhibitor of NF-kB, then the expression level of MHCIα, MHCIIß, and Ii was decreased significantly (P < 0.01) than the control group. The transcription levels of these genes were decreased 0.64, 0.27, and 0.26 respectively. Simultaneously, the expression levels of IFN-ß, IFN-γ, and IL-1ß were also significantly (P < 0.01) up-regulated (increased) 7.8, 22.7, and 5 times higher than the control group. It was found that up-regulation of STING and NF-κB pathways are directly involved in the regulation of inflammatory cytokines (IFN-ß, IFN-γ, and IL-1ß), MHC molecules (MHCIα, MHCIIß), and Ii gene. The results also showed that the gene regulation pathways consecutively increased the expression levels of MDA5, STING, IRF7, and NF-kB. It is conducted that the expression levels of cytokines, MHC molecules, and li gene were increased by STING and NF-kB pathways.

Blood compatibility improvement of titanium oxide film modified by doping La(2)O(3).

La(2)O(3) doped titanium oxide (TiO(2)) films with different concentration were deposited by means of the Radio-Frequency magnetron sputtering technique. The microstructure and surface properties of TiO(2) films were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and contact angle test. The blood compatibility of the specimens was evaluated by tests of platelet adhesion. Results show that pure rutile phase is formed in doped samples and La(2)O(3) incorporation significantly improves the wettability and hemocompatibility of TiO(2) films. Our studies demonstrate that La(2)O(3) doped TiO(2) films are potentially useful biomaterials with good blood compatibility.

Broad spectral response of an individual tellurium nanobelt grown by molecular beam epitaxy.

The detection of broad wavelengths from the near-ultraviolet to near-infrared regime using functional semiconductor nanostructures is of great importance in either fundamental research or technological application. In this work, we report high-performance optoelectronic nanodevices based on a single Te nanobelt grown by molecular beam epitaxy. The photodetector demonstrates a fast photoresponse time (a rise time of 510 µs and a decay time of 300 µs), a high photoresponsivity of 254.2 A W-1, an external quantum efficiency of 8.6 × 104%, a large detectivity of 8.3 × 108 Jones, on/off ratio of 3 orders, broadband response from the near-ultraviolet to near-infrared region, and robust photocurrent stability and reproducibility. The photodetector with superior performances based on the individual one-dimensional Te nanobelt consequently shows great promise for further optoelectronic device applications.

Field-Free Deterministic Magnetization Switching with Ultralow Current Density in Epitaxial Au/Fe4N Bilayer Films.

Current-induced magnetization switching was investigated in Au/Fe4N bilayer films grown by a plasma-assisted molecular beam epitaxy (PA-MBE) system. Depending on lattice distortion and interfacial coupling induced by substrates, the Fe4N layer could be divided into two sublayers having different magnetic anisotropies. The bottom sublayer shows perpendicular magnetic anisotropy (PMA), while the top one has in-plane magnetic anisotropy (IMA). Coupling between the two sublayers provides an extra in-plane effective field and enables a field-free magnetization switching in the bilayer films. By summarizing a series of Hall measurements, a switching phase diagram was obtained. Temperature-dependent switching behaviors demonstrate that the threshold current density for the field-free magnetization switching, which is much smaller than that of pervious reports, increases with decreasing temperature and shows similar temperature dependences to those of coercivity.

Charge Density Wave Phase Transitions in Large-Scale Few-Layer 1T-VTe2 Grown by Molecular Beam Epitaxy.

Charge density wave (CDW) as a novel effect in two-dimensional transition metal dichalcogenides (TMDs) has obtained a rapid rise of interest for its physical nature and potential applications in oscillators and memory devices. Here, we report var der Waals epitaxial growth of centimeter-scale 1T-VTe2 thin films on mica by molecular beam epitaxy. The VTe2 thin films showed sudden resistance change at temperatures of 240 and 135 K, corresponding to two CDW phase transitions driven by temperature. Moreover, the phase transitions can be driven by an electric field due to local Joule heating, and the corresponding resistance states are nonvolatile and controllable, which could be applied to the memory device where the logic states can be switched by an electric field. The multistage CDW phase transitions in the VTe2 thin films could be contributed to electron-phonon coupling in the two-dimensional VTe2, which is supported by twice pronounced Raman blue shifts of the vibration modes associated with in-plane phonons at CDW phase transition temperature. The results open up a new platform for understanding the microscopic physical essence and electrical control of CDW phases of TMDs, expanding the functionalities of these materials for memory applications.

Charge density determination in icosahedral AlPdMn quasicrystal using quantitative convergent beam electron diffraction.

Charge density distribution in icosahedral AlPdMn quasicrystal has been studied on a single-crystal specimen by using quantitative convergent beam electron diffraction (QCBED) technique. The QCBED systematic row method was used in the refinement of structure factors. To refine the low-order structure factors, the wave-mechanical formulation of electron diffraction dynamical theory was used in the calculation of electron diffraction intensities for the quasicrystal in fitting the experimental intensity line scan profiles. The shapes of atomic surfaces (occupation domains) were described with symmetry-adapted series of surface harmonics. An iterative procedure was used in determination of structure factors of the quasicrystal. The structure factors of nine strongest symmetry inequivalent reflections according to X-ray diffraction experiment were refined with QCBED technique. The average of refinement results for a given reflection performed on several CBED patterns, which were slightly different in orientation and sample thickness, and on different line scans, was taken as the value of structure factor for the reflection. The obtained structure factors for electrons were transformed into X-ray structure factors with Mott formula. The bonding charge density map for the quasicrystal was constructed with the obtained nine structure factors. Assuming that the atoms are spheres, the gain or loss of electrons for different atoms were calculated. It shows that identical atoms can have different valences at different kinds of positions. The bonding charge is localized along certain directions.

Bipolar resistance switching in transparent ITO/LaAlO3/SrTiO3 memristors.

We report reversible bipolar resistance switching behaviors in transparent indium-tin oxide (ITO)/LaAlO3/SrTiO3 memristors at room temperature. The memristors exhibit high optical transparency, long retention, and excellent antifatigue characteristics. The high performances are promising for employing ITO/LaAlO3/SrTiO3 memristors in nonvolatile transparent memory and logic devices. The nonvolatile resistance switching behaviors could be attributed to the migration of positively charged oxygen vacancies from the SrTiO3 substrate to the LaAlO3 film, resulting in Poole-Frenkel emission for the low resistance state and thermionic emission for the high resistance state.