Emergent Ferromagnetism in CaRuO3/CaMnO3 (111)-Oriented Superlattices.

The boundary between CaRuO3 and CaMnO3 is an ideal test bed for emergent magnetic ground states stabilized through interfacial electron interactions. In this system, nominally antiferromagnetic and paramagnetic materials combine to yield interfacial ferromagnetism in CaMnO3 due to electron leakage across the interface. In this work, we show that the crystal symmetry at the surface is a critical factor determining the nature of the interfacial interactions. Specifically, by growing CaRuO3/CaMnO3 heterostructures along the (111) instead of the (001) crystallographic axis, we achieve a 3-fold enhancement of the magnetization and involve the CaRuO3 layers in the ferromagnetism, which now spans both constituent materials. The stabilization of a net magnetic moment in CaRuO3 through strain effects has been long-sought but never consistently achieved, and our observations demonstrate the importance of interface engineering in the development of new functional heterostructures.

Mesenchymal stem cell-derived exosomes improve diabetes mellitus-induced myocardial injury and fibrosis via inhibition of TGF-ß1/Smad2 signaling pathway.

The aim of this study is to investigate  the effect of mesenchymal stem cell (MSC)-derived exosomes on diabetes mellitus-induced myocardial injury, and the underlying mechanism. Thirty adult male Sprague Dawley rats were randomly assigned to three groups of ten rats each: normal control group, diabetic control group and MSC exosomes group. Exosomes were isolated from MSCs through gradient ultracentrifugation. With the exception of normal control, diabetes mellitus (DM) was induced in the rats with a single intraperitoneal injection of 30 mg/kg body weight streptozotocin (STZ) in 0.1 mol/L sodium citrate buffer. Rats in MSC exosomes group were intravenously injected with MSC-derived exosomes once a week for 12 weeks. Left ventricular collagen (LVC) level was measured using acid hydrolysis method. Fatty acid transporters (FATPs) and fatty acid beta oxidase (FA-ß-oxidase) were determined using enzyme-linked immunosorbent assay (ELISA). Gene and protein expressions of TGF-ß and Smad2 were determined using real-time quantitative polymerase chain reaction (qRT-PCR) and Western blotting. Flow cytometric analysis and Western blotting revealed positive expression of exosomal specific marker, CD63. The level of LVC was significantly higher in diabetic control group than in normal control group, but was significantly reduced after treatment with MSC-derived exosomes (p < 0.05). The levels of FATPs and FA-ß-oxidase were significantly lower in diabetic control group than in normal control group (p < 0.05). However, treatment with MSC-derived exosomes significantly increased the levels of these proteins (p < 0.05). The levels of expression of TGF-ß1 and Smad2 mRNAs were significantly higher in the diabetic control group than in normal control group, but were significantly reduced after treatment with MSC-derived exosomes (p < 0.05). The expressions of TGF-ß1 and Smad2 proteins were also significantly upregulated in diabetic control group, when compared with normal control group (p < 0.05). However, treatment with MSC-derived exosomes significantly down-regulated the expression of these proteins (p < 0.05). The results obtained in this study indicate that MSC-derived exosomes improve DM-induced myocardial injury and fibrosis via inhibition of TGF-ß1/Smad2 signaling pathway.

Nitrogen Doped Graphene Supported Pt Nanoflowers as Electrocatalysts for Oxidation of Formaldehyde.

A facile Pt nanoflowers/nitrogen-doped graphene (PtNFs/NG) electrocatalyst was prepared via depositing Pt nanoflowers (PtNFs) onto the nitrogen-doped graphene (NG) matrix with urea as the nitrogen source and PtNFs/NG modified glassy carbon electrode (GCE) was prepared by electro-chemical method. Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Raman spectroscope, X-ray photoelectron spectroscopy (XPS) and Scanning electron microscope (SEM) were used to characterize the resulting composites. Also oxidation of formaldehyde on the resulting PtNFs/NG modified electrode was investigated. The influence of deposition time, electrodeposition potential and formaldehyde concentration on electrooxidation of formaldehyde was detected, the experimental results indicate the high performance of PtNFs/NG catalyst for formaldehyde oxidation is at electrodeposition time of 300 s with the applied potential of −0.3 V. Electrochemical process, electrocatalytic stability and chronoamperometry were also inspected, it was indicated that formalde-hyde oxidation reaction on the PtNFs/NG electrode is diffusion-controlled and PtNFs/NG exhibits a high catalytic activity, stability as well as excellent poisoning-tolerance towards formaldehyde oxidation, which is attributed to the synergistic effect of PtNFs and NG. It turns out that PtNFs/NG can be used in direct liquid-feed fuel cells as a promising alternative catalyst.

Counting injury deaths: a comparison of two definitions and two countries.

OBJECTIVES: This study sought to examine the discrepancy in counting injury deaths according to two definitions, that is, (a) external cause of injury as the underlying cause of death (UCOD), and (b) with mention of external cause of injury, and differences in certification practices between Taiwan and the USA. METHODS: We calculated the percentage (U/M%) in which external cause of injury was selected as the UCOD (U) among deaths with mention (M) of external cause of injury anywhere on the death certificate to assess the discrepancy between the two definitions in counting injury deaths. RESULTS: The discrepancy was small in Taiwan and in the USA for transport injuries (with U/M% 99% and 98%) and intentional self-harm (100% and 100%) and large for accidental suffocation (64% and 29%) as well as complications of medical and surgical care (61% and 10%). The magnitude of discrepancy was not consistent between countries in accidental falls (96% vs 81%) and accidental drowning (80% vs 97%). Certifiers in Taiwan were more likely to report an accidental fall in Part I of the death certificate and less likely to report medical conditions (such as stroke, Alzheimer's disease or Parkinson's disease, etc) with accidental suffocation than their counterpart US certifiers. CONCLUSIONS: The counting of injury deaths according to two definitions varied by external cause of injury as well as between countries. For some external causes of injury with high discrepancies, we suggest presenting the number of injury deaths according to two definitions.

Reduction-Induced Magnetic Behavior in LaFeO3-δ Thin Films.

The effect of oxygen reduction on the magnetic properties of LaFeO3-δ (LFO) thin films was studied to better understand the viability of LFO as a candidate for magnetoionic memory. Differences in the amount of oxygen lost by LFO and its magnetic behavior were observed in nominally identical LFO films grown on substrates prepared using different common methods. In an LFO film grown on as-received SrTiO3 (STO) substrate, the original perovskite film structure was preserved following reduction, and remnant magnetization was only seen at low temperatures. In a LFO film grown on annealed STO, the LFO lost significantly more oxygen and the microstructure decomposed into La- and Fe-rich regions with remnant magnetization that persisted up to room temperature. These results demonstrate an ability to access multiple, distinct magnetic states via oxygen reduction in the same starting material and suggest LFO may be a suitable materials platform for nonvolatile multistate memory.

Charge-Transfer-Induced Interfacial Ferromagnetism in Ferromagnet-Free Oxide Heterostructures.

Due to the strong interlayer coupling between multiple degrees of freedom, oxide heterostructures have demonstrated exotic properties that are not shown by their bulk counterparts. One of the most interesting properties is ferromagnetism at the interface formed between "nonferromagnetic" compounds. Here we report on the interfacial ferromagnetic phase induced in the superlattices consisting of the two paramagnetic oxides CaRuO3 (CRO) and LaNiO3 (LNO). By varying the sublayer thickness in the superlattice period, we demonstrate that the ferromagnetic order has been established in both CaRuO3 and LaNiO3 sublayers, exhibiting an identical Curie temperature of ∼75 K. The X-ray absorption spectra suggest a strong charge transfer from Ru to Ni at the interface, triggering superexchange interactions between Ru/Ni ions and giving rise to the emergent ferromagnetic phase. Moreover, the X-ray linear dichroism spectra reveal the preferential occupancy of the d3z2-r2 orbital for the Ru ions and the dx2-y2 orbital for the Ni ions in the heterostructure. This leads to different magnetic anisotropy of the superlattices when they are dominated by CRO or LNO sublayers. This work clearly demonstrates a charge-transfer-induced interfacial ferromagnetic phase in the whole ferromagnet-free oxide heterostructures, offering a feasible way to tailor oxide materials for desired functionalities.

Investigating Anisotropic Magnetoresistance in Epitaxially Strained CoFe Thin Films on a Flexible Mica.

This study investigates the crystal structure, epitaxial relation, and magnetic properties in CoFe thin films deposited on a flexible mica substrate. The epitaxial growth of CoFe thin films was successfully achieved by DC magnetron sputtering, forming three CoFe(002) domains exhibiting four-fold symmetry on the mica substrate. A notable achievement of this work was the attainment of the highest anisotropic magnetoresistance (AMR) value reported to date on a flexible substrate. Additionally, it was observed that the magnetic characteristics of the CoFe films on the flexible mica substrate display reversibility upon strain release. More importantly, the AMR effect of epitaxial CoFe films on flexible mica shows lesser dependence on the crystalline orientation and remains the same under different bending states. These findings demonstrate the potential of utilizing CoFe films on flexible substrates to develop wearable magnetoresistance sensors with diverse applications.

Current-induced Néel order switching facilitated by magnetic phase transition.

Terahertz (THz) spin dynamics and vanishing stray field make antiferromagnetic (AFM) materials the most promising candidate for the next-generation magnetic memory technology with revolutionary storage density and writing speed. However, owing to the extremely large exchange energy barriers, energy-efficient manipulation has been a fundamental challenge in AFM systems. Here, we report an electrical writing of antiferromagnetic orders through a record-low current density on the order of 106 A cm-2 facilitated by the unique AFM-ferromagnetic (FM) phase transition in FeRh. By introducing a transient FM state via current-induced Joule heating, the spin-orbit torque can switch the AFM order parameter by 90° with a reduced writing current density similar to ordinary FM materials. This mechanism is further verified by measuring the temperature and magnetic bias field dependences, where the X-ray magnetic linear dichroism (XMLD) results confirm the AFM switching besides the electrical transport measurement. Our findings demonstrate the exciting possibility of writing operations in AFM-based devices with a lower current density, opening a new pathway towards pure AFM memory applications.

[Clinical Characteristics and Survival Analysis of Patients with IgD Multiple Myeloma].

OBJECTIVE: To explore the clinical features, prognosis and survival of patients with IgD multiple myeloma (MM). METHODS: The clinical data of 20 patients with IgD MM was analyzed retrospectively. The prognostic factors and survival analysis was carried out. We summarized their clinical characteristics. The survival analysis was carried out by Kaplan-Meier method, and the prognostic factor were analyzed by using log-rank test for single factor analysis of observation index. Variables of P<0.15 in single factor analysis were enrolled in multifactor cox regression analysis. RESULTS: IgD MM patients accounted for 4.3% of all MM patients in the same period, among which 80% were male, the median age of patients was 57.5(35-77) years old, 90% of the patients belongs to λ light chain type. At the time of diagnosis, 18 patients (90%) were in DS-Ⅲ stages, while 10 patients were in ISS-Ⅲ stage. The first clinical manifestations were fatigue, bone pain, kidney function impairment, anemia (Hb<100 g/L) in 14 cases (70%), 12 cases (60%) with osteolytic bone destruction≥3, combined with renal impairment in 8 cases (40%), and elevated blood calcium in 11 cases (51.4%). In only 5 patients the ratio of albumin to globntin was inverted, hypoalbuminemia accounted for 40%, and globulin increase accounted for only 15%. FISH results showed that the positive rate of 1q21 amplification (50%) was the highest, and it was easy to occur at the same time as other cytogenetic abnormalities. Extramedullary infiltration occurred in 4 cases (20%). The analysis of prognostic factors showed that only the increase of lactate dehydrogenase (LDH) level was an independent poor prognostic factor for IgD MM patients. Extramedullary infiltration and various cytogenetic abnormalities were found in 2 IgD MM patients with primary drug resistance, suggesting that extramedullary infiltration and various cytogenetic abnormalities may be prognostic factors, but the difference was not statistically significant, Which maybe related to the small sample size. All 20 patients were treated with bortezomib-containing regimen, of which 19 patients were evaluated, 17 patients (89.4%) showed effective, including CR+VGPR (52.6%), PR (31.5%), MR (5.3%), 2 patients primary drug resistance. The median PFS and OS was 9.5 and 10.5 months, respectively. CONCLUSION: IgD MM is a rare and invasive disease. Increased LDH is an independent prognostic factor. Bortizomib-containing regimen can improve the prognosis of IgD MM patients.

[Clinical Analysis of 46 Cases of Multiple Myeloma with Extramedullary Disease].

OBJECTIVE: To investigate the effect of clinical baseline data on prognosis in patients with multiple myeloma (MM) complicated by extramedullary disease (EMD). METHODS: The clinical data of 46 MM patients with EMD were retrospectively analyzed. The clinical data and survival prognosis of MM patients in primary EMD group and recurrent EMD group were analyzed. The classified baseline data were expressed by the number of cases (percentage), the χ2 test was used to compare the two classification data groups. The OS and PFS curves were drawn by multiplication positive limit method (Kaplan-Meier). Log-rank test was used for the univariate analysis of prognosis, and COX proportional risk regression model was used for the multiple factors of prognosis. RESULTS: ß 2 microglobulin≥2.7 g/L, lactic dehydrogenase≥250 U/L, serum calcium≥2.75 mmol/L, plasma cells in bone marrow≥60% were the poor prognostic factors for PFS. Serum calcium≥2.75 mmol/L and the plasma cells in bone marrow≥60% were the poor prognostic factors for OS. Multivariate regression analysis enroling the statistically significant factors in univariate analysis baseline date in factors in showed that plasma cell level≥60% in bone marrow was independent poor prognostic factors for PFS, and serum calcium≥2.75 mmol/L was an independent poor prognostic factor for OS. The IgG type is the most common type of MM complicated by EMD. The remission depth of primary EMD group≥VGPR was lower than that of recurrent EMD group, and there was significant difference between the two groups (P<0.05), and the median OS time of patients with primary EMD group was shorter than that of patients with recurrent EMD group, the difference was statistically significant (P<0.05). The 3-year survival rates of primary EMD group and recurrent EMD group were 10.0% and 34%, respectively, there was no significant difference between the two groups (P>0.05). The 5-year survival rate was 0 and 20%, respectively, there was significant difference between the two groups (P<0.05). CONCLUSION: The remission depth of primary EMD group≥VGPR is lower than that of recurrent EMD group，and the OS time of patients in primary EMD group is shorter than that in recurrent EMD group. Bortezomib-based chemotherapy could not improve the prognosis of patients with primary EMD and recurrent EMD, and the prognosis of patients with primary EMD is even worse.

[Clinical Characteristic, Prognosis and Treatment Outcome of Elderly Multiple Myeloma Patients with Impaired Renal Function].

OBJECTIVE: To explore the risk factors, prognosis and curative effect of elderly patients with MM renal damage. METHODS: 118 patients with primary elderly MM treated in our hospital from January 2011 to December 2018, were enrolled analyzed retrospectively. The clinical characteristics and prognosis of renal function impairment group (RI group) and normal renal function group (non-RI group) were compared. The difference of renal efficacy and survival benefit between the patients treated with bortezomib, thalidomide (combination group) and chemotherapy regimen containing only one of them (single drug group) in RI group was compared. RESULTS: Univariate analysis showed that DS stage, pulmonary infection, uric acid, ß 2 microglobulin and leukocyte in RI group were higher than those in non-RI group, but hemoglobin was lower than that in non-RI group (P<0.05). Multivariate logistic regression analysis showed that ß 2 microglobulin was the independent risk factor for renal damage in elderly patients with MM. Kaplan-Meier method showed that the OS and PFS in RI group were significantly lower than those in non-RI group (P<0.05). The renal efficacy in the combined treatment group was significantly better than that of the single drug group (P<0.05), and it could bring benefit to the PFS of the elderly patients with MM renal damage (P<0.05). CONCLUSION: The prognosis of elderly MM patients with impaired renal function is poor. The prognosis of these patients can be improved by selecting chemotherapy regimen containing bortezomib and thalidomide at the same time, and monitoring, controlling all kinds of risk factors actively.

Probing the low-temperature limit of the quantum anomalous Hall effect.

Quantum anomalous Hall effect has been observed in magnetically doped topological insulators. However, full quantization, up until now, is limited within the sub-1 K temperature regime, although the material's magnetic ordering temperature can go beyond 100 K. Here, we study the temperature limiting factors of the effect in Cr-doped (BiSb)2Te3 systems using both transport and magneto-optical methods. By deliberate control of the thin-film thickness and doping profile, we revealed that the low occurring temperature of quantum anomalous Hall effect in current material system is a combined result of weak ferromagnetism and trivial band involvement. Our findings may provide important insights into the search for high-temperature quantum anomalous Hall insulator and other topologically related phenomena.

Termination switching of antiferromagnetic proximity effect in topological insulator.

This work reports the ferromagnetism of topological insulator, (Bi,Sb)2Te3 (BST), with a Curie temperature of approximately 120 K induced by magnetic proximity effect (MPE) of an antiferromagnetic CrSe. The MPE was shown to be highly dependent on the stacking order of the heterostructure, as well as the interface symmetry: Growing CrSe on top of BST results in induced ferromagnetism, while growing BST on CrSe yielded no evidence of an MPE. Cr-termination in the former case leads to double-exchange interactions between Cr3+ surface states and Cr2+ bulk states. This Cr3+-Cr2+ exchange stabilizes the ferromagnetic order localized at the interface and magnetically polarizes the BST Sb band. In contrast, Se-termination at the CrSe/BST interface yields no detectable MPE. These results directly confirm the MPE in BST films and provide critical insights into the sensitivity of the surface state.

Evidence of Spin Frustration in a Vanadium Diselenide Monolayer Magnet.

Monolayer VSe2 , featuring both charge density wave and magnetism phenomena, represents a unique van der Waals magnet in the family of metallic 2D transition-metal dichalcogenides (2D-TMDs). Herein, by means of in situ microscopy and spectroscopic techniques, including scanning tunneling microscopy/spectroscopy, synchrotron X-ray and angle-resolved photoemission, and X-ray absorption, direct spectroscopic signatures are established, that identify the metallic 1T-phase and vanadium 3d1 electronic configuration in monolayer VSe2 grown on graphite by molecular-beam epitaxy. Element-specific X-ray magnetic circular dichroism, complemented with magnetic susceptibility measurements, further reveals monolayer VSe2 as a frustrated magnet, with its spins exhibiting subtle correlations, albeit in the absence of a long-range magnetic order down to 2 K and up to a 7 T magnetic field. This observation is attributed to the relative stability of the ferromagnetic and antiferromagnetic ground states, arising from its atomic-scale structural features, such as rotational disorders and edges. The results of this study extend the current understanding of metallic 2D-TMDs in the search for exotic low-dimensional quantum phenomena, and stimulate further theoretical and experimental studies on van der Waals monolayer magnets.

Local Regression and Global Information-Embedded Dimension Reduction.

A large family of algorithms for unsupervised dimension reduction is based on both the local and global structures of the data. A fundamental step in these methods is to model the local geometrical structure of the data. However, the previous methods mainly ignore two facts in this step: 1) the dimensionality of the data is usually far larger than the number of local data, which is a typical ill-posed problem and 2) the data might be polluted by noise. These facts normally may lead to an inaccurate learned local structure and may degrade the final performance. In this paper, we propose a novel unsupervised dimension reduction method with the ability to address these problems effectively while also preserving the global information of the input data. Specifically, we first denoise the local data by preserving their principal components and we then apply a regularization term to the local modeling function to solve the illposed problem. Then, we use a linear regression model to capture the local geometrical structure, which is demonstrated to be insensitive to the parameters. Finally, we propose two criteria to simultaneously model both the local and the global information. Theoretical analyses for the relations between the proposed methods and some classical dimension-reduction methods are presented. The experimental results from various databases demonstrate the effectiveness of our methods.

LLE Score: A New Filter-Based Unsupervised Feature Selection Method Based on Nonlinear Manifold Embedding and Its Application to Image Recognition.

The task of feature selection is to find the most representative features from the original high-dimensional data. Because of the absence of the information of class labels, selecting the appropriate features in unsupervised learning scenarios is much harder than that in supervised scenarios. In this paper, we investigate the potential of locally linear embedding (LLE), which is a popular manifold learning method, in feature selection task. It is straightforward to apply the idea of LLE to the graph-preserving feature selection framework. However, we find that this straightforward application suffers from some problems. For example, it fails when the elements in the feature are all equal; it does not enjoy the property of scaling invariance and cannot capture the change of the graph efficiently. To solve these problems, we propose a new filter-based feature selection method based on LLE in this paper, which is named as LLE score. The proposed criterion measures the difference between the local structure of each feature and that of the original data. Our experiments of classification task on two face image data sets, an object image data set, and a handwriting digits data set show that LLE score outperforms state-of-the-art methods, including data variance, Laplacian score, and sparsity score.

Phase-driven magneto-electrical characteristics of single-layer MoS2.

Magnetism of the MoS2 semiconducting atomic layer was highlighted for its great potential in the applications of spintronics and valleytronics. In this study, we demonstrate an evolution of magneto-electrical properties of single layer MoS2 with the modulation of defect configurations and formation of a partial 1T phase. With Ar treatment, sulfur was depleted within the MoS2 flake leading to a 2H (low-spin) → partial 1T (high-spin) phase transition. The phase transition was accompanied by the development of a ferromagnetic phase. Alternatively, the phase transition could be driven by the desorption of S atoms at the edge of MoS2via O2 treatment while with a different ordering magnitude in magnetism. The edge-sensitive magnetism of the single-layer MoS2 was monitored by magnetic force microscopy and validated by a first-principle calculation with graded-Vs (sulfur vacancy) terminals set at the edge, where band-splitting appeared more prominent with increasing Vs. Treatment with Ar and O2 enabled a dual electrical characteristic of the field effect transistor (FET) that featured linear and saturated responses of different magnitudes in the Ids-Vds curves, whereas the pristine MoS2 FET displayed only a linear electrical dependency. The correlation and tuning of the Vs-1T phase transition would provide a playground for tailoring the phase-driven properties of MoS2 semiconducting atomic layers in spintronic applications.

Competing Anisotropy-Tunneling Correlation of the CoFeB/MgO Perpendicular Magnetic Tunnel Junction: An Electronic Approach.

We intensively investigate the physical principles regulating the tunneling magneto-resistance (TMR) and perpendicular magnetic anisotropy (PMA) of the CoFeB/MgO magnetic tunnel junction (MTJ) by means of angle-resolved x-ray magnetic spectroscopy. The angle-resolved capability was easily achieved, and it provided greater sensitivity to symmetry-related d-band occupation compared to traditional x-ray spectroscopy. This added degree of freedom successfully solved the unclear mechanism of this MTJ system renowned for controllable PMA and excellent TMR. As a surprising discovery, these two physical characteristics interact in a competing manner because of opposite band-filling preference in space-correlated symmetry of the 3d-orbital. An overlooked but harmful superparamagnetic phase resulting from magnetic inhomogeneity was also observed. This important finding reveals that simultaneously achieving fast switching and a high tunneling efficiency at an ultimate level is improbable for this MTJ system owing to its fundamental limit in physics. We suggest that the development of independent TMR and PMA mechanisms is critical towards a complementary relationship between the two physical characteristics, as well as the realization of superior performance, of this perpendicular MTJ. Furthermore, this study provides an easy approach to evaluate the futurity of any emerging spintronic candidates by electronically examining the relationship between their magnetic anisotropy and transport.

A facile green antisolvent approach to Cu2+-doped ZnO nanocrystals with visible-light-responsive photoactivities.

An environmentally benign antisolvent method has been developed to prepare Cu(2+)-doped ZnO nanocrystals with controllable dopant concentrations. A room temperature ionic liquid, known as a deep eutectic solvent (DES), was used as the solvent to dissolve ZnO powders. Upon the introduction of the ZnO-containing DES into a bad solvent which shows no solvation to ZnO, ZnO was precipitated and grown due to the dramatic decrease of solubility. By adding Cu(2+) ions to the bad solvent, the growth of ZnO from the antisolvent process was accompanied by Cu(2+) introduction, resulting in the formation of Cu(2+)-doped ZnO nanocrystals. The as-prepared Cu(2+)-doped ZnO showed an additional absorption band in the visible range (400-800 nm), which conduced to an improvement in the overall photon harvesting efficiency. Time-resolved photoluminescence spectra, together with the photovoltage information, suggested that the doped Cu(2+) may otherwise trap photoexcited electrons during the charge transfer process, inevitably depressing the photoconversion efficiency. The photoactivity of Cu(2+)-doped ZnO nanocrystals for photoelectrochemical water oxidation was effectively enhanced in the visible region, which achieved the highest at 2.0 at% of Cu(2+). A further increase in the Cu(2+) concentration however led to a decrease in the photocatalytic performance, which was ascribed to the significant carrier trapping caused by the increased states given by excessive Cu(2+). The photocurrent action spectra illustrated that the enhanced photoactivity of the Cu(2+)-doped ZnO nanocrystals was mainly due to the improved visible photon harvesting achieved by Cu(2+) doping. These results may facilitate the use of transition metal ion-doped ZnO in other photoconversion applications, such as ZnO based dye-sensitized solar cells and magnetism-assisted photocatalytic systems.

Instrument for x-ray absorption spectroscopy with in situ electrical control characterizations.

We report a synchrotron-based setup capable of performing x-ray absorption spectroscopy and x-ray magnetic circular dichroism with simultaneous electrical control characterizations. The setup can enable research concerning electrical transport, element- and orbital-selective magnetization with an in situ fashion. It is a unique approach to the real-time change of spin-polarized electronic state of a material/device exhibiting magneto-electric responses. The performance of the setup was tested by probing the spin-polarized states of cobalt and oxygen of Zn(1-x)Co(x)O dilute magnetic semiconductor under applied voltages, both at low (~20 K) and room temperatures, and signal variations upon the change of applied voltage were clearly detected.