Nonlinear Thermo‐Electro‐Mechanical Behaviors of Ag/BaTiO3 Composites

The focus of this study is to understand the influences of blending silver (Ag) phase into barium titanate (BaTiO3) ceramic on its thermal, mechanical and dielectric properties. Silver-barium titanate (Ag/BaTiO3) active composites with varying silver composition were fabricated using powder metallurgy method. Coefficient of thermal expansion (CTE) and heat capacity were measured by thermal mechanical analyzer (TMA) and differential scanning calorimetry (DSC), respectively. Hot disk technique was employed to determine the thermal conductivity. Addition of silver did not change the phase transformation temperatures. CTE stays constant at each crystalline phase, but increases as BaTiO3’s crystal structure changes from orthorhombic to tetragonal phase and further to cubic. Increase of silver content significantly enhances the thermal conductivity. Elastic and dielectric constants were determined using resonant ultrasound spectroscopy (RUS) and dielectric (impedance) spectroscopy, respectively. Young’s modulus decreases as the increase of silver composition, while the dielectric constant was significantly improved by blending silver. Two peaks were observed on dielectric constant around the transformation temperatures, with a larger magnitude at the Curie point. Micromechanics models based on detailed microstructures, either generated randomly by computer algorithm or created by converting scanning electron microscope (SEM) images, were created to numerically study the effects of microstructures on the effective properties of Ag/BaTiO3 composite. Numerical results showed that microstructure induced anisotropy is negligible and the effective properties are insensitive to loading directions. Effective CTE is insensitive to the yielding of silver particles, porosity, and the elastic modulus of BaTiO3. The predictions of CTE and elastic constants were pretty close to the experiment results, while the effective thermal conductivity and dielectric constant predictions underestimated the measured values. The hysteretic mechanical behavior of Ag/BaTiO3 composite was measured under cyclic uniaxial compressive loading using materials test system (MTS). Specimens with 5 vol% and 13 vol% silver composition were broken before the maximum stress was reached. The fractured specimens showed a fracture angle of approximate 45⁰C. Furthermore, a one-dimensional constitutive model based on the thermodynamics of irreversible process was presented to model the hysteretic response from experiment

mRNA/microRNA Profile at the Metamorphic Stage of Olive Flounder (Paralichthys olivaceus)

Flatfish is famous for the asymmetric transformation during metamorphosis. The molecular mechanism behind the asymmetric development has been speculated over a century and is still not well understood. To date, none of the metamorphosis-related genes has been identified in flatfish. As the first step to screen metamorphosis-related gene, we constructed a whole-body cDNA library and a whole-body miRNA library in this study and identified 1051 unique ESTs, 23 unique miRNAs, and 4 snoRNAs in premetamorphosing and prometamorphosing Paralichthys olivaceus. 1005 of the ESTs were novel, suggesting that there was a special gene expression profile at metamorphic stage. Four miRNAs (pol-miR-20c, pol-miR-23c, pol-miR-130d, and pol-miR-181e) were novel to P. olivaceus; they were characterized as highly preserved homologies of published miRNAs but with at least one nucleotide differed. Representative 24 mRNAs and 23 miRNAs were quantified during metamorphosis of P. olivaceus by using quantitative RT PCR or stem-loop qRT PCR. Our results showed that 20 of mRNAs might be associated with early metamorphic events, 10 of mRNAs might be related with later metamorphic events, and 16 of miRNAs might be involved in the regulation of metamorphosis. The data provided in this study would be helpful for further identifying metamorphosis-related gene in P. olivaceus

Repair of fingertip defect with reverse digital artery island flap and repair of donor site with digital dorsal advancement flap

ObjectiveThe reverse digital artery island flap (RDAF) is widely used in repairing fingertip skin defects based on its good appearance and practicability. However, the donor area of the flap needs skin grafting, which can lead to complications. This retrospective study explored the clinical application of digital dorsal advance flap (DDAF) in repairing the donor site of the reverse digital artery island flap.MethodFrom June 2019 to February 2022, 17 patients with a soft tissue defect of the finger had been restored with the reverse digital artery island flap, and at the same time, the donor area was repaired with digital dorsal advance flap (DDAF). The sensitivity, the active range of motion (ROM) and patient satisfaction were assessed after the operation.ResultsAll flaps survived completely without skin grafting with only one linear scar. The sensory and motor functions of all patients recovered well. Assessment based on the Michigan Hand Outcomes Questionnaire (MHQ) showed satisfactory functional recovery for all patients.ConclusionsReconstruction using RDAF combined with DDAF represents an effective alternative for repairing fingertip skin defects

Mechanically Robust and Spectrally Selective Convection Shield for Daytime Subambient Radiative Cooling

As a passive cooling strategy, radiative cooling is becoming anappealing approach to dissipate heat from terrestrial emitters to the outer space. However, the currently achieved cooling performance is still underperforming due to considerable solar radiation absorbed by the emitter and nonradiative heat transferred from the surroundings. Here, we proposed a mechanically robust and spectrally selective convection shield composed of nanoporous composite fabric (NCF) to achieve daytime subambient radiative cooling. By selectively reflecting ∼95% solar radiation, transmitting ∼84% thermal radiation, and suppressing the nonradiative heat transferred from warmer surroundings, the NCF-based radiative cooler demonstrated an average daytime temperature reduction of ∼4.9 °C below the ambient temperature, resulting in an average net radiative cooling power of ∼48 W/m2 over a 24 h measurement. In addition, we also modeled the potential cooling capacity of the NCF-based radiative cooler and demonstrated that it can cover the cooling demands of energy-efficient residential buildings in most regions of China. Excellent spectral selectivity, mechanical strength, and weatherability of the NCF cover enable a much broader selection for the emitters, which is promising in the real-world deployment of direct daytime subambient radiative cooling

Somatic mutation and gain of copy number of PIK3CA in human breast cancer

INTRODUCTION: Phosphatidylinositol 3-kinases (PI3Ks) are a group of lipid kinases that regulate signaling pathways involved in cell proliferation, adhesion, survival, and motility. Even though PIK3CA amplification and somatic mutation have been reported previously in various kinds of human cancers, the genetic change in PIK3CA in human breast cancer has not been clearly identified. METHODS: Fifteen breast cancer cell lines and 92 primary breast tumors (33 with matched normal tissue) were used to check somatic mutation and gene copy number of PIK3CA. For the somatic mutation study, we specifically checked exons 1, 9, and 20, which have been reported to be hot spots in colon cancer. For the analysis of the gene copy number, we used quantitative real-time PCR and fluorescence in situ hybridization. We also treated several breast cancer cells with the PIK3CA inhibitor LY294002 and compared the apoptosis status in cells with and without PIK3CA mutation. RESULTS: We identified a 20.6% (19 of 92) and 33.3% (5 of 15) PIK3CA somatic mutation frequency in primary breast tumors and cell lines, respectively. We also found that 8.7% (8 of 92) of the tumors harbored a gain of PIK3CA gene copy number. Only four cases in this study contained both an increase in the gene copy number and a somatic mutation. In addition, mutation of PIK3CA correlated with the status of Akt phosphorylation in some breast cancer cells and inhibition of PIK3CA-induced increased apoptosis in breast cancer cells with PIK3CA mutation. CONCLUSION: Somatic mutation rather than a gain of gene copy number of PIK3CA is the frequent genetic alteration that contributes to human breast cancer progression. The frequent and clustered mutations within PIK3CA make it an attractive molecular marker for early detection and a promising therapeutic target in breast cancer

Variation of Tensor Force due to Nuclear Medium Effect

The enhancement of $J^{\pi}(T)$=3$^{+}$(0) state with isospin $T=0$ excited by the tensor force in the free $^{6}$Li nucleus has been observed, for the first time, relative to a shrinkable excitation in the $^{6}$Li cluster component inside its host nucleus. Comparatively, the excitation of $J^{\pi}(T)$=0$^{+}$(1) state with isospin $T=1$ for these two $^{6}$Li formations take on an approximately equal excitation strength. The mechanism of such tensor force effect was proposed due to the intensive nuclear medium role on isospin $T$=0 state.Comment: 6 pages, 4 figure

Aspect of Clusters Correlation at Light Nuclei Excited State

The correlation of $\alpha\alpha$ was probed via measuring the transverse momentum $p_{T}$ and width $\delta p_{T}$ of one $\alpha$, for the first time, which represents the spatial and dynamical essentialities of the initial coupling state in $^{8}$Be nucleus. The weighted interaction vertex of 3$\alpha$ reflected by the magnitudes of their relative momentums and relative emission angles proves the isosceles triangle configuration for 3$\alpha$ at the high excited energy analogous Hoyle states.Comment: 8 pages, 9 figure

Multi-alpha Boson Gas state in Fusion Evaporation Reaction and Three-body Force

The experimental evidence for the $\alpha$ Boson gas state in the $^{11}$C+$^{12}$C$\rightarrow$$^{23}$Mg$^{\ast}$ fusion evaporation reaction is presented. By measuring the $\alpha$ emission spectrum with multiplicity 2 and 3, we provide insight into the existence of a three-body force among $\alpha$ particles. The observed spectrum exhibited distinct tails corresponding to $\alpha$ particles emitted in pairs and triplets consistent well with the model-calculations of AV18-UX and chiral effective field theory of NV2-3-la*, indicating the formation of $\alpha$ clusters with three-body force in the Boson gas state.Comment: 7 pages, 6 figure

Load Balancing Opportunistic Routing for Cognitive Radio Ad Hoc Networks

Recent research activities have shown that opportunistic routing can achieve considerable performance gains in Cognitive Radio Ad hoc Networks (CRAHNs). Most of these studies focused on designing appropriate metrics to select and prioritize the forwarding candidates. However, in multiple-flow networks, a small number of nodes may always be with the higher priority order for different flows. Thus, some nodes may easily become overloaded with too much traffic and be severely congested. To overcome this problem, we propose a load balancing opportunistic routing (LBOR) scheme to maximize the total throughput of the whole network. We first formulate the problem of maximizing the total throughput of the network as a linear programming problem. Then, we develop heuristic load balancing candidate forwarder sorting and selection algorithms. Simulation results and comparisons demonstrate that our proposed LBOR scheme outperforms existing opportunistic routing protocols with nonload balancing methods in CRAHNs