Voltage-Controlled Magnon Transistor via Tuning Interfacial Exchange Coupling.

Magnon transistors that can effectively regulate magnon transport by an electric field are desired for magnonics, which aims to provide a Joule-heating free alternative to the conventional electronics owing to the electric neutrality of magnons (the key carriers of spin-angular momenta in the magnonics). However, also due to their electric neutrality, magnons have no access to directly interact with an electric field and it is thus difficult to manipulate magnon transport by voltages straightforwardly. Here, we demonstrated a gate voltage (V_{g}) applied on a nonmagnetic metal and magnetic insulator (MI) interface that bent the energy band of the MI and then modulated the probability for conduction electrons in the nonmagnetic metal to tunnel into the MI, which can consequently enhance or weaken the spin-magnon conversion efficiency at the interface. A voltage-controlled magnon transistor based on the magnon-mediated electric current drag (MECD) effect in a Pt-Y_{3}Fe_{5}O_{12}-Pt sandwich was then experimentally realized with V_{g} modulating the magnitude of the MECD signal. The obtained efficiency (the change ratio between the MECD voltage at ±V_{g}) reached 10%/(MV/cm) at 300 K. This prototype of magnon transistor offers an effective scheme to control magnon transport by a gate voltage.

Efficient Spin-to-Charge Conversion via Altermagnetic Spin Splitting Effect in Antiferromagnet RuO_{2}.

The relativistic spin Hall effect and inverse spin Hall effect enable the efficient generation and detection of spin current. Recently, a nonrelativistic altermagnetic spin splitting effect (ASSE) has been theoretically and experimentally reported to generate time-reversal-odd spin current with controllable spin polarization in antiferromagnet RuO_{2}. The inverse effect, electrical detection of spin current via ASSE, still remains elusive. Here we show the spin-to-charge conversion stemming from ASSE in RuO_{2} by the spin Seebeck effect measurements. Unconventionally, the spin Seebeck voltage can be detected even when the injected spin current is polarized along the directions of either the voltage channel or the thermal gradient, indicating the successful conversion of x- and z-spin polarizations into the charge current. The crystal axes-dependent conversion efficiency further demonstrates that the nontrivial spin-to-charge conversion in RuO_{2} is ascribed to ASSE, which is distinct from the magnetic or antiferromagnetic inverse spin Hall effects. Our finding not only advances the emerging research landscape of altermagnetism, but also provides a promising pathway for the spin detection.

Average and individual differences between the 12-item MOS Short-form Health Survey version 2 (SF-12 V.2) and the veterans RAND 12-item Health Survey (VR-12) in the Chinese population.

BACKGROUND: The 12-item MOS Short-form Health Survey version 2 (SF-12v2) and the Veterans RAND 12-item Health Survey (VR-12) are generic health-related quality of life measures. They are fairly similar, but their differences in scores have not been assessed. Therefore, this study aimed to assess the differences between the SF-12v2 and the VR-12 in a Chinese population. METHODS: We conducted a household survey of 500 Chinese adults in Hong Kong. Both the SF-12v2 and the VR-12 were self-administered. The physical component summary score (PCS) and the mental component summary score (MCS) of each instrument were computed using well established algorithms. Their mean differences were assessed using 95% confidence interval (CI), and their individual differences were assessed by Bland-Altman analysis. RESULTS: The participants had a mean age of 38 years (range: 18-80 years). The mean PCS and MCS scores of the SF-12v2 were 50.3 (SD = 6.5) and 49.0 (SD = 9.0), while those of the VR-12 were 49.6 (SD = 6.2) and 49.7 (SD = 8.8), respectively. The corresponding paired differences (SF-12v2-VR-12) of the PCS and MCS were 0.8, 95% CI (0.4-1.1) and - 0.7, 95% CI (- 1.2 to - 0.2), respectively. All confidence limits fell within the minimal clinical important difference (MCID) of 3. The 95% limits of agreement were - 7.0, 8.5 for PCS and - 11.2, 9.9 for MCS, which fell outside the corresponding MCID for individual responses. CONCLUSION: The SF-12v2 and the VR-12 reached mean equivalence at the group sample level, but there was a range of individual differences.

Development of a data-driven COVID-19 prognostication tool to inform triage and step-down care for hospitalised patients in Hong Kong: a population-based cohort study.

BACKGROUND: This is the first study on prognostication in an entire cohort of laboratory-confirmed COVID-19 patients in the city of Hong Kong. Prognostic tool is essential in the contingency response for the next wave of outbreak. This study aims to develop prognostic models to predict COVID-19 patients' clinical outcome on day 1 and day 5 of hospital admission. METHODS: We did a retrospective analysis of a complete cohort of 1037 COVID-19 laboratory-confirmed patients in Hong Kong as of 30 April 2020, who were admitted to 16 public hospitals with their data sourced from an integrated electronic health records system. It covered demographic information, chronic disease(s) history, presenting symptoms as well as the worst clinical condition status, biomarkers' readings and Ct value of PCR tests on Day-1 and Day-5 of admission. The study subjects were randomly split into training and testing datasets in a 8:2 ratio. Extreme Gradient Boosting (XGBoost) model was used to classify the training data into three disease severity groups on Day-1 and Day-5. RESULTS: The 1037 patients had a mean age of 37.8 (SD ± 17.8), 53.8% of them were male. They were grouped under three disease outcome: 4.8% critical/serious, 46.8% stable and 48.4% satisfactory. Under the full models, 30 indicators on Day-1 and Day-5 were used to predict the patients' disease outcome and achieved an accuracy rate of 92.3% and 99.5%. With a trade-off between practical application and predictive accuracy, the full models were reduced into simpler models with seven common specific predictors, including the worst clinical condition status (4-level), age group, and five biomarkers, namely, CRP, LDH, platelet, neutrophil/lymphocyte ratio and albumin/globulin ratio. Day-1 model's accuracy rate, macro-/micro-averaged sensitivity and specificity were 91.3%, 84.9%/91.3% and 96.0%/95.7% respectively, as compared to 94.2%, 95.9%/94.2% and 97.8%/97.1% under Day-5 model. CONCLUSIONS: Both Day-1 and Day-5 models can accurately predict the disease severity. Relevant clinical management could be planned according to the predicted patients' outcome. The model is transformed into a simple online calculator to provide convenient clinical reference tools at the point of care, with an aim to inform clinical decision on triage and step-down care.

Spin-orbit torque switching in a T-type magnetic configuration with current orthogonal to easy axes.

Different symmetry breaking ways determine various magnetization switching modes driven by spin-orbit torques (SOT). For instance, an applied or effective field parallel to applied current is indispensable to switch magnetization with perpendicular anisotropy by SOT. Besides of this mode, here we experimentally demonstrate a distinct field-free switching mode in a T-type magnetic system with structure of MgO/CoFeB/Ta/CoFeB/MgO where a perpendicular layer with tilted easy axis was coupled to an in-plane layer with a uniaxial easy axis. Current was applied orthogonal to both easy axes and thus also normal to an in-plane effective field experienced by the perpendicular layer. Dynamic calculation shows perpendicular layer could be switched at the same time as the in-plane layer is switched. These field-free switching modes realized in the same T-type magnetic system might expedite the birth of multi-state spin memories or spin logic devices which could be operated by all electric manners.

Magnon Valve Effect between Two Magnetic Insulators.

The key physics of the spin valve involves spin-polarized conduction electrons propagating between two magnetic layers such that the device conductance is controlled by the relative magnetization orientation of two magnetic layers. Here, we report the effect of a magnon valve which is made of two ferromagnetic insulators (YIG) separated by a nonmagnetic spacer layer (Au). When a thermal gradient is applied perpendicular to the layers, the inverse spin Hall voltage output detected by a Pt bar placed on top of the magnon valve depends on the relative orientation of the magnetization of two YIG layers, indicating the magnon current induced by the spin Seebeck effect at one layer affects the magnon current in the other layer separated by Au. We interpret the magnon valve effect by the angular momentum conversion and propagation between magnons in two YIG layers and conduction electrons in the Au layer. The temperature dependence of the magnon valve ratio shows approximately a power law, supporting the above magnon-electron spin conversion mechanism. This work opens a new class of valve structures beyond the conventional spin valves.

Controllable synthesis of ferromagnetic-antiferromagnetic core-shell NWs with tunable magnetic properties.

Several nanotechnology applications are based on the promising scheme of highly anisotropic magnetic nanomaterials. Using this idea, we investigated the structure, magnetic properties, and interfacial exchange anisotropy effects of the Ni/Cr2O3 and Fe/Cr2O3 core-shell nanowires (NWs) geometry. A template-based strategy was developed to synthesize Ni (Fe)-Cr2O3 core-shell NWs, which combines a wet-chemical route and electrodeposition within the nanopores of the membranes. Structural determination in correlation with magnetic testing shows that the crystalline Cr2O3-nanoshells (NSs) cause an enhanced exchange bias, providing an extra source of anisotropy that leads to their magnetic stability. This core-shell NWs geometry, with enhanced anisotropy, should, therefore, motivate further study related to the applicability of anisotropic nanostructures. Our design opens a new pathway to obtain optimized heterostructured nanomaterials exhibiting tunable magnetic properties.

Magnetic response of hybrid ferromagnetic and antiferromagnetic core-shell nanostructures.

The synthesis of FeTiO3-Ni(Ni80Fe20) core-shell nanostructures by a two-step method (sol-gel and DC electrodeposition) has been demonstrated. XRD analysis confirms the rhombohedral crystal structure of FeTiO3(FTO) with space group R3[combining macron]. Transmission electron microscopy clearly depicts better morphology of nanostructures with shell thicknesses of ∼25 nm. Room temperature magnetic measurements showed significant enhancement of magnetic anisotropy for the permalloy (Ni80Fe20)-FTO over Ni-FTO core-shell nanostructures. Low temperature magnetic measurements of permalloy-FeTiO3 core-shell structure indicated a strong exchange bias mechanism with magnetic coercivity below the antiferromagnetic Neel temperature (TN = 59 K). The exchange bias is attributed to the alignment of magnetic moments in the antiferromagnetic material at low temperature. Our scheme opens a path towards optimum automotive systems and wireless communications wherein broader bandwidths and smaller sizes are required.

Upregulation of mitochondrial protease HtrA2/Omi contributes to manganese-induced neuronal apoptosis in rat brain striatum.

Manganese (Mn) is an essential trace element that is required for normal brain functioning. However, excessive intake of Mn has been known to lead to neuronal loss and clinical symptoms resembling idiopathic Parkinson's disease (IPD), whose precise molecular mechanism remains largely elusive. In the study, we established a Mn-exposed rat model and identified a mitochondrial protease, the mature form of high temperature requirement A2 (HtrA2/Omi), which was significantly upregulated in rat brain striatum after Mn exposure. Western blot and immunohistochemical analyses revealed that the expression of mature HtrA2 was remarkably increased following Mn exposure. In addition, immunofluorescence assay demonstrated that overexposure to Mn could lead to significant elevation in the number of HtrA2-positive neurons. Accordingly, the expression of X-linked inhibitor of apoptosis protein (XIAP), a well-characterized target of HtrA2-mediated proteolysis, was progressively decreased following Mn exposure, and was correlated with increased level of active caspase-3. Further, we showed that Mn exposure decreased the viability and induced apparent apoptosis of NFG-differentiated PC12 cells. Importantly, the expression of HtrA2 was progressively increased, whereas the level of cellular XIAP was reduced during Mn-induced apoptosis. In addition, blockage of HtrA2 activity with UCF-101 restored Mn-induced reduction in XIAP expression. Finally, we observed that UCF-101 treatment ameliorated Mn-induced apoptosis in PC12 cells. Collectively, these findings suggested that upregulated HtrA2 played a role in Mn-induced neuronal death in brain striatum.

Multiplex polymerase chain reaction assay for the detection of minute virus of mice and mouse parvovirus infections in laboratory mice.

Mouse parvoviruses are among the most prevalent infectious pathogens in contemporary mouse colonies. To improve the efficiency of routine screening for mouse parvovirus infections, a multiplex polymerase chain reaction (PCR) assay targeting the VP gene was developed. The assay detected minute virus of mice (MVM), mouse parvovirus (MPV) and a mouse housekeeping gene (α-actin) and was able to specifically detect MVM and MPV at levels as low as 50 copies. Co-infection with the two viruses with up to 200-fold differences in viral concentrations can easily be detected. The multiplex PCR assay developed here could be a useful tool for monitoring mouse health and the viral contamination of biological materials.

Detection of rat parvovirus type 1 and rat minute virus type 1 by polymerase chain reaction.

Two newly recognized parvovirus species, rat parvovirus 1 (RPV-1) and rat minute virus 1 (RMV-1), were recently identified in naturally infected rats. In this study, two polymerase chain reaction (PCR) assays were developed to specifically detect RPV-1 and RMV-1. The RPV-1 PCR assay amplified the expected 487-bp deoxyribonucleic acid (DNA) fragment only in the presence of RPV-1 DNA; the RMV-1 PCR assay amplified the expected 843-bp product only from RMV-1 DNA, not from other rodent parvoviruses. The RPV-1 and the RMV-1 PCR assays detected approximately 18 and 70 copies of DNA template, respectively. These two PCR assays were shown to be sensitive, specific and rapid methods for detecting RPV-1 and RMV-1 infections in rats. These assays may also be valuable for evaluation of biological specimens for parvovirus contamination.

[Effects of simulated flight hypobaric hypoxia and oxygen inhalation on free radical metabolism in various organs of mice].

Objective. To investigate the effects of two types of simulated flight conditions (hypobaric hypoxia and hypobaric oxygen inhalation) on free radical metabolism in various organs of mice. Method. Sixty male Kunming mice were randomly divided into six groups (n=10 each). The experiment comprises two parts. The first part included three groups: normal controls (A1), 1500 m hypobaric hypoxia for 4 wk (B1) and 8 wk (C1). The second part included another three groups: normal control (A2), 5500 m hypobaric oxygen inhalation for 4 wk (B2) and 8 wk (C2). The exposure time in hypobaric chamber was 2 h/d, 3 d/wk. After experiment, caudal blood was taken for routine examination. The mice were decapitated on the next day and brain, heart, lung, liver and kidney homogenates were prepared for measuring malondialdehyde (MDA) content and superoxide dismutase (SOD) activity. Result. Lipid peroxides in lung was significantly increased in C1 group, and the content of myocardial MDA and myocardial SOD activities in C2 group were markedly higher than those in A2 group. There were no significant differences among body weights, mean corpuscular indices and hemoglobin content in the normal control, hypobaric hypoxia and hypobaric oxygen inhalation groups. It demonstrates that repeated mild hypobaric hypoxia for 8 wk causes free radical damage of lung and repeated exposure to 5500 m hypobaric oxygen inhalation for 8 wk may lead to myocardial peroxidative injury in mice. Conclusion. Simulated flight hypobaric hypoxia and oxygen inhalation may lead to free radicals damage of lung and myocardial peroxidative injury in mice.

Expression of Sendai virus nucleocapsid protein in a baculovirus expression system and application to diagnostic assays for Sendai virus infection.

The most common diagnostic technique for the detection of Sendai virus infection in rodents is serological evaluation by enzyme-linked immunosorbent assay (ELISA) with semipurified preparations of whole virions as antigens. This assay often suffers from a lack of specificity. The goal of the present project was to develop more specific antigens for use in diagnostic testing by producing recombinant antigens in insect cells. To identify viral proteins immunoreactive in multiple laboratory rodent species, Western blots (immunoblots) of viral polypeptides were probed with immune sera from mice, rats, and hamsters. The nucleocapsid protein (NP) reacted with immune sera from all species tested. Therefore, the NP gene was selected for cloning and expression in a baculovirus. To construct the recombinant, complementary DNA was synthesized by reverse transcription PCR from Sendai virus RNA with primers from the 5' and 3' termini of the NP-coding region. Amplified DNA was cloned into a baculovirus transfer vector (pBlueBacHis A) and was cotransfected with wild-type baculovirus into insect cells. Baculovirus recombinants containing the NP gene were identified by PCR. Evaluation of the recombinant proteins expressed in insect cells by Western blot analysis revealed specific reactivity with immune sera. In comparison with conventional ELISAs that use whole virions as the antigen, ELISAs that use recombinant NP were more specific.