Octahedral Distortion and Displacement-Type Ferroelectricity with Switchable Photovoltaic Effect in a 3d^{3}-Electron Perovskite System

Because of the half-filled t_{2g}-electron configuration, the BO_{6} octahedral distortion in a 3d^{3} perovskite system is usually very limited. In this Letter, a perovskitelike oxide Hg_{0.75}Pb_{0.25}MnO_{3} (HPMO) with a 3d^{3} Mn^{4+} state was synthesized by using high pressure and high temperature methods. This compound exhibits an unusually large octahedral distortion enhanced by approximately 2 orders of magnitude compared with that observed in other 3d^{3} perovskite systems like RCr^{3+}O_{3} (R=rare earth). Essentially different from centrosymmetric HgMnO_{3} and PbMnO_{3}, the A-site doped HPMO presents a polar crystal structure with the space group Ama2 and a substantial spontaneous electric polarization (26.5  μC/cm^{2} in theory) arising from the off-center displacements of A- and B-site ions. More interestingly, a prominent net photocurrent and switchable photovoltaic effect with a sustainable photoresponse were observed in the current polycrystalline HPMO. This Letter provides an exceptional d^{3} material system which shows unusually large octahedral distortion and displacement-type ferroelectricity violating the "d^{0}-ness" rule.

[Research progression of gene fusion detection technology based on next generation sequencing in tumor companion diagnostics]

Gene fusion is one of the mechanisms that promote tumor development. It is also an important cause for the poor prognosis of patients. The detection of gene fusion is crucial for the recognition of tumor biomarker, cancer subtype classification, and clinical medication guidance. Appropriate methods can help the early diagnosis and avoid ineffective medication. Traditional tests include fluorescence in situ hybridization (FISH), immunohistochemistry (IHC), reverse transcription of PCR (RT-PCR), and next generation sequencing (NGS). The next generation sequencing (NGS) mainly includes: whole genome sequencing (WGS), whole transcriptome sequencing (WTS) and target sequencing (hybridization capture method/amplicon method). In clinical concomitant diagnostic applications, some factors such as operability, time/money costs, and the level of expertise required for data analysis should be considered. This article concludes with a discussion of the technical principles of different detection methods and advantages/limitations. Meanwhile, it provides reference opinions for the detection methods of gene fusion.

[The characteristics of non-alcoholic fatty liver disease and its associated factors in patients with rheumatoid arthritis]

Objective: To investigate the characteristics of non-alcoholic fatty liver disease (NAFLD) and its associated factors in rheumatoid arthritis (RA) patients. Methods: This cross-sectional study recruited 385 RA patients [including 72 (18.7%) male and 313 (81.3%) female] who received abdominal sonographic examination from August 2015 to May 2021 at Department of Rheumatology, Sun Yat-Sen Memorial Hospital. There were 28 RA patients at 16-29 years old and 32, 80, 121, 99, 25 at 30-39, 40-49, 50-59, 60-69, ≥ 70 years old, respectively. Demographic and clinical data were collected including age, gender, history of alcohol consumption, disease duration, body mass index (BMI), waist circumference, blood pressure, RA disease activity indicators and previous medications. Logistic regression analyses were used to identify the associated factors of NAFLD in RA patients. Results: The prevalence of NAFLD was 24.2% (93/385) in RA patients, 26.3% (21/80) in 40-49 age group and 33.1% (40/121) in 50-59 age group. There were 22.1% (85/385) and 3.6% (14/385) RA patients with overweight and obese, in which the prevalence of NAFLD was 45.9% (39/85) and 78.6% (11/14) respectively, which was 2.6 folds and 4.5 folds that of RA patients with normal BMI. Although there was no significant difference of age, gender and RA disease activity indicators between RA patients with or without NAFLD, those with NAFLD had higher proportions of metabolic diseases including obese (11.8% vs. 1.0%), central obesity (47.3% vs. 16.8%), hypertension (45.2% vs. 29.8%) and type 2 diabetes mellitus (24.7% vs. 12.0%), consistent with higher levels of total cholesterol [(5.33±1.31) mmol/L vs. (4.73±1.12) mmol/L], triglyceride [(1.51±1.08) mmol/L vs. (0.98±0.54) mmol/L] and low-density lipoprotein cholesterol [(3.37±0.97) mmol/L vs. (2.97±0.78) mmol/L, all P<0.05]. Multivariate logistic regression analysis showed that BMI (OR=1.314) and triglyceride (OR=1.809) were the independent factors positively associated with NAFLD in RA patients. Conclusion: NAFLD is a common comorbidity in RA patients, especially in those with middle-aged, overweight or obese, which is associated with high BMI or high triglyceride. Screening and management of NAFLD in RA patients especially those with overweight, obese or dyslipidemia should be emphasized.

[Analysis of public appeals for vaccination in Guangzhou's Government Hotline from 2018 to 2020]

This study analyzed the characteristics and change trend of Guangzhou citizens' demands related to vaccination through government hotlines 12345 and 12320 from 2018 to 2020. It understood the hotspots and needs of the public for vaccination work, analyzed the problems existing in vaccination work, and provided reference and suggestions for health departments to improve vaccination services and formulate relevant policies: to timely improve the professional ability and knowledge reserve of hotline personnel; to strengthen the construction of vaccination service system;to optimize the appointment vaccination service application; to scientifically purchase HPV vaccine and ensure the production and supply of vaccine.

[The characteristics and associated factors of functional limitation in patients with rheumatoid arthritis]

Objective: To investigate the characteristics of functional limitation and associated factors in patients with rheumatoid arthritis (RA). Methods: Consecutive patients with RA were recruited from August 2015 to June 2019 at Department of Rheumatology, Sun Yat-Sen Memorial Hospital. Demographic and clinical characteristics including age, gender, erythrocyte sedimentation rate (ESR), visual analogue scale (VAS) of pain, clinical disease activity index (CDAI), modified total Sharp score were collected. Physical function was assessed by the Stanford health assessment questionnaire disability index (HAQ-DI).Ordered logistic regression was used to analyze the related factors of HAQ-DI. Results: A total of 643 RA patients were finally recruited including 114 males and 529 females with mean age (49.7±12.9) years. There were 399 (62.1%) patients having different degrees of functional limitation, who were classified as mild (293, 45.6%), moderate (73, 11.4%) and severe (33, 5.1%). The prevalence of functional limitation was positively correlated with age and disease activity. The most restricted activity was walking [43.5% (280/643)], followed by gripping [36.1% (232/643)], reaching [35.5% (228/643)], daily activities [33.4% (215/643)], hygiene [33.0% (212/643)], dressing and grooming [29.7% (191/643)] and arising [29.1% (187/643)], and the last eating [18.4% (118/643)]. Multivariate ordered logistic regression analysis showed that age (OR=1.019, 95%CI 1.004-1.035),pain VAS (OR=1.820, 95%CI 1.616-2.050), ESR (OR=1.009, 95%CI 1.001-1.017), CDAI (OR=1.080, 95%CI 1.059-1.102) and modified total Sharp score (OR=1.010, 95%CI 1.004-1.015) were associated factors of functional limitation. Conclusion: The majority RA patients have functional limitation. Age, pain and active disease are independent associated factors. Therefore, target treatment and control of pain should be emphasized in RA patients.

Development of the Soft X-ray AGM-AGS RIXS beamline at the Taiwan Photon Source

We report on the development of a high-resolution and highly efficient beamline for soft X-ray resonant inelastic X-ray scattering (RIXS) located at the Taiwan Photon Source. This beamline adopts an optical design that uses an active grating monochromator (AGM) and an active grating spectrometer (AGS) to implement the energy compensation principle of grating dispersion. Active gratings are utilized to diminish defocus, coma and higher-order aberrations, as well as to decrease the slope errors caused by thermal deformation and optical polishing. The AGS is mounted on a rotatable granite platform to enable momentum-resolved RIXS measurements with scattering angles over a wide range. Several high-precision instruments developed in-house for this beamline are described briefly. The best energy resolution obtained from this AGM-AGS beamline was 12.4 meV at 530 eV, achieving a resolving power of 4.2 × 104, while the bandwidth of the incident soft X-rays was kept at 0.5 eV. To demonstrate the scientific impact of high-resolution RIXS, we present an example of momentum-resolved RIXS measurements on a high-temperature superconducting cuprate, i.e. La2-xSrxCuO4. The measurements reveal the A1g buckling phonons in superconducting cuprates, opening a new opportunity to investigate the coupling between these phonons and charge-density waves.

[Predictive value of anti-mutated citrullinated vimentin antibody on one-year radiographic progression in patients with rheumatoid arthritis]

Objective: To investigate the value of baseline anti-mutated citrullinated vimentin (MCV) antibody for predicting one-year radiographic progression in patients with rheumatoid arthritis (RA). Methods: Consecutive RA patients were recruited from November 2014 to July 2018 at Department of Rheumatology, Sun Yat-sen Memorial Hospital, Clinical data were collected including disease activity score in 28 joints with four variables including C-reactive protein (CRP).Serum anti-MCV antibody at baseline was detected by enzyme-linked immunosorbent assay. X ray assessment of both hands/wrists was performed and assessed according to the Sharp/van der Heijde modified score (mTSS) at baseline and the 12th month. Univariate and multivariate logistic regression analyses were used to identify the risk factors for one-year radiographic progression. Results: Among 220 RA patients recruited, the positive rate of anti-MCV antibody at baseline was 77.7%. Compared with those with negative anti-MCV antibody, RA patients with positive anti-MCV antibody had higher disease activity score in 28 joints with four variables induding CRP [3.8 (2.4, 5.0) vs. 3.1 (2.1, 4.0), P=0.007], more physical dysfunction (21.6% vs. 8.2%, P=0.033) and higher radiographic indicators including mTSS [11 (2, 27) vs. 4 (1, 10), P=0.003], joint space narrowing [JSN, 4 (0, 14) vs. 2 (0, 6), P=0.024] and joint erosion[JE, 5 (1, 18)vs. 3 (0, 5), P=0.003]. After one-year follow-up, sixty-six RA patients (30.0%) developed radiographic progression, the percentage of whom was significantly higher in positive anti-MCV group than that in negative anti-MCV group (33.9% vs.16.3%, P=0.018). Multivariate logistic regression analysis suggested that positive anti-MCV antibody at baseline was an independent risk factor for one-year radiographic progression (OR=2.341, 95%CI 1.002-5.469). Conclusion: Positive anti-MCV antibody at baseline predicts one-year radiographic progression in RA patients. In the future, anti-MCV antibody can be used not only as a supplementary laboratory marker, but also in disease activity assessment and prognosis prediction for RA.

Charge disproportionation and nano phase separation in [Formula: see text]

We have successfully grown centimeter-sized layered [Formula: see text] single crystals under high oxygen pressures of 120-150 bar by the floating zone technique. This enabled us to perform neutron scattering experiments where we observe close to quarter-integer magnetic peaks below [Formula: see text] that are accompanied by steep upwards dispersing spin excitations. Within the high-frequency Ni-O bond stretching phonon dispersion, a softening at the propagation vector for a checkerboard modulation can be observed. We were able to simulate the magnetic excitation spectra using a model that includes two essential ingredients, namely checkerboard charge disproportionation and nano phase separation. The results thus suggest that charge disproportionation is preferred instead of a Jahn-Teller distortion even for this layered [Formula: see text] system.

Synthesis, characterization, kinetic drug release and anticancer activity of bisphosphonates multi-walled carbon nanotube conjugates

The statistical proof that most forms of cancer metastasize to bone tissue has redirected research focus to the development of efficient secondary bone cancer treatment regimens. Bisphosphonates (BPs) have been earmarked as a drug of choice for bone metastasis. However, they have a shortcoming of being released before reaching targeted sites due to their low molecular weight. In haste to attain increased efficacy, there is a tendency for drug overdose to occur, resulting in systemic toxicity. One way to curb this is by employing drug delivery systems for targeted and controlled release of the drugs. Having been explored as versatile and innovative drug carriers, multi-walled carbon nanotubes (MWCNTs) have emerged as potential drug delivery systems. Hence, in the present study, alendronate, neridronate and pamidronate are three classes of bisphosphonates that were conjugated onto multi-walled carbon nanotubes. Conjugation was confirmed by characterization techniques including SEM, TEM, EDX, FTIR, Raman and TGA. Drug release studies were also conducted at pH 1.2, 5.5 and 7.4 to study the mechanism of release for neridronate. Results obtained were fitted into Zero order (42.6%), Higuchi (26%) and Korsmeyer-Peppas (22%). The best models describing the release of neridronate from MWCNTs were Zero order, Higuchi and Korsmeyer-Peppas at pH 1.2, 5.5 and 7.4, respectively. A tetrazolium cell viability assay was performed to assess the anticancer activity of the MWCNTs conjugated BPs.

Superconductivity in a unique type of copper oxide

The mechanism of superconductivity in cuprates remains one of the big challenges of condensed matter physics. High-T c cuprates crystallize into a layered perovskite structure featuring copper oxygen octahedral coordination. Due to the Jahn Teller effect in combination with the strong static Coulomb interaction, the octahedra in high-T c cuprates are elongated along the c axis, leading to a 3dx 2-y 2 orbital at the top of the band structure wherein the doped holes reside. This scenario gives rise to 2D characteristics in high-T c cuprates that favor d-wave pairing symmetry. Here, we report superconductivity in a cuprate Ba2CuO4-y , wherein the local octahedron is in a very exceptional compressed version. The Ba2CuO4-y compound was synthesized at high pressure at high temperatures and shows bulk superconductivity with critical temperature (T c ) above 70 K at ambient conditions. This superconducting transition temperature is more than 30 K higher than the T c for the isostructural counterparts based on classical La2CuO4 X-ray absorption measurements indicate the heavily doped nature of the Ba2CuO4-y superconductor. In compressed octahedron, the 3d3z 2-r 2 orbital will be lifted above the 3dx 2-y 2 orbital, leading to significant 3D nature in addition to the conventional 3dx 2-y 2 orbital. This work sheds important light on advancing our comprehensive understanding of the superconducting mechanism of high T c in cuprate materials.

Cancer is not a risk factor for bullous pemphigoid: 10-year population-based cohort study

BACKGROUND

Bullous pemphigoid (BP) is the most common autoimmune bullous disease. Whether there is an increased risk for subsequent BP among patients with cancer is still unclear.

OBJECTIVES

To evaluate the risk for subsequent BP in patients with cancer.

METHODS

This nationwide population-based cohort study was based on data obtained from the Taiwan National Health Insurance Database between 2000 and 2011. A total of 36 838 patients with cancer and 147 352 age-, sex- and index-date-matched controls were recruited. The hazard ratio (HR) of subsequent BP in the patients with cancer was analysed using a Fine-Gray competing risk regression model with mortality as the competing event.

RESULTS

The incidence of BP per 100 000 person-years was 17·2 in the patients with cancer and 19·8 in the controls; therefore, the crude incidence rate ratio was 0·87 [95% confidence interval (CI) 0·53-1·36]. The HR of subsequent BP in the patients with cancer was 0·47 (95% CI 0·23-0·94) using the Fine-Gray competing risk regression model. Age (HR 1·05, 95% CI 1·03-1·07), diabetes mellitus (HR 1·69, 95% CI 1·10-2·59) and cerebrovascular disease (HR 2·14, 95% CI 1·36-3·34) were independent risk factors for BP.

CONCLUSIONS

The incidence of BP in patients with cancer was not higher than in the control group. Cancer is not a risk factor for BP.

Coulomb Correlations Intertwined with Spin and Orbital Excitations in LaCoO_{3}

We carried out temperature-dependent (20-550 K) measurements of resonant inelastic x-ray scattering on LaCoO_{3} to investigate the evolution of its electronic structure across the spin-state crossover. In combination with charge-transfer multiplet calculations, we accurately quantified the renomalized crystal-field excitation energies and spin-state populations. We show that the screening of the effective on-site Coulomb interaction of 3d electrons is orbital selective and coupled to the spin-state crossover in LaCoO_{3}. The results establish that the gradual spin-state crossover is associated with a relative change of Coulomb energy versus bandwidth, leading to a Mott-type insulator-to-metal transition.

Neuropsychiatric symptoms in Alzheimer's disease: associations with caregiver burden and treatment outcomes

BACKGROUND

Caregivers play a major role in providing care for patients with Alzheimer's disease (AD) and are themselves at higher risk of health comorbidities.

AIM

To address the impact of neuropsychiatric symptoms of patients in different stages of AD on their caregivers' burden.

DESIGN

This prospective study enrolled 260 AD patients with clinical dementia rating (CDR) of 0.5, 1 and 2 at a tertiary medical center.

METHODS

All patients were tested using the mini-mental state examination (MMSE), the cognitive abilities screening instrument (CASI), the neuropsychiatric inventory (NPI) and the CDR scale. Data regarding therapeutic outcomes of anti-Alzheimer's drugs were also collected. Caregivers were tested using NPI.

RESULTS

The mean follow-up interval was 25.0 ± 12.2 months, and two patients died during follow-up. NPI-burden was positively correlated with NPI-sum ( r  = 0.822, P  <   0.001) but negatively correlated with years of education ( r  = -0.140, P  =   0.024), CASI score ( r  = -0.259, P  <   0.001) and MMSE score ( r  = -0.262, P  <0.001). Multiple linear regression analysis showed that only NPI-sum was independently associated with mean NPI-burden. Both higher mean CASI and MMSE scores had better therapeutic outcome of anti-Alzheimer's drugs ( P  =   0.001 and P =   0.005, respectively).

CONCLUSIONS

The severity of neuropsychiatric symptoms in patients with AD was positively associated with caregiver's stress, and patients with better cognitive functions, under treatment with anti-Alzheimer's drugs, had better therapeutic outcomes. To reduce the impact of neuropsychiatric symptoms, it is crucial to detect dementia in its early phases and provide early intervention with anti-Alzheimer's drugs, which might help decrease the caregiver burden, thereby improving their quality of life.

Jahn-Teller distortion driven magnetic polarons in magnetite

The first known magnetic mineral, magnetite, has unusual properties, which have fascinated mankind for centuries; it undergoes the Verwey transition around 120 K with an abrupt change in structure and electrical conductivity. The mechanism of the Verwey transition, however, remains contentious. Here we use resonant inelastic X-ray scattering over a wide temperature range across the Verwey transition to identify and separate out the magnetic excitations derived from nominal Fe²⁺ and Fe³⁺ states. Comparison of the experimental results with crystal-field multiplet calculations shows that the spin–orbital dd excitons of the Fe²⁺ sites arise from a tetragonal Jahn-Teller active polaronic distortion of the Fe²⁺O₆ octahedra. These low-energy excitations, which get weakened for temperatures above 350 K but persist at least up to 550 K, are distinct from optical excitations and are best explained as magnetic polarons.

The Verwey transition of magnetite is complex due to the coexistence of strong correlations and electron-phonon coupling. Here, the authors use resonant inelastic X-ray scattering to show evidence for magnetic polarons in magnetite and provide insight into the nature of the transition.

Orbital Engineering in Nickelate Heterostructures Driven by Anisotropic Oxygen Hybridization rather than Orbital Energy Levels

Resonant inelastic x-ray scattering is used to investigate the electronic origin of orbital polarization in nickelate heterostructures taking LaTiO_{3}-LaNiO_{3}-3×(LaAlO_{3}), a system with exceptionally large polarization, as a model system. We find that heterostructuring generates only minor changes in the Ni 3d orbital energy levels, contradicting the often-invoked picture in which changes in orbital energy levels generate orbital polarization. Instead, O K-edge x-ray absorption spectroscopy demonstrates that orbital polarization is caused by an anisotropic reconstruction of the oxygen ligand hole states. This provides an explanation for the limited success of theoretical predictions based on tuning orbital energy levels and implies that future theories should focus on anisotropic hybridization as the most effective means to drive large changes in electronic structure and realize novel emergent phenomena.

Raman and fluorescence characteristics of resonant inelastic X-ray scattering from doped superconducting cuprates

Measurements of spin excitations are essential for an understanding of spin-mediated pairing for superconductivity; and resonant inelastic X-ray scattering (RIXS) provides a considerable opportunity to probe high-energy spin excitations. However, whether RIXS correctly measures the collective spin excitations of doped superconducting cuprates remains under debate. Here we demonstrate distinct Raman- and fluorescence-like RIXS excitations of Bi_1.5Pb_0.6Sr_1.54CaCu₂O_8+δ. Combining photon-energy and momentum dependent RIXS measurements with theoretical calculations using exact diagonalization provides conclusive evidence that the Raman-like RIXS excitations correspond to collective spin excitations, which are magnons in the undoped Mott insulators and evolve into paramagnons in doped superconducting compounds. In contrast, the fluorescence-like shifts are due primarily to the continuum of particle-hole excitations in the charge channel. Our results show that under the proper experimental conditions RIXS indeed can be used to probe paramagnons in doped high-T_c cuprate superconductors.

An unusual high-spin ground state of Co3+ in octahedral coordination in brownmillerite-type cobalt oxide

High-spin ground state of Co³⁺ was found in brownmillerite-like Sr₂Co_1.2Ga_0.8O₅ by low-temperature NPD and XAS study.

Highly efficient beamline and spectrometer for inelastic soft X-ray scattering at high resolution

The design, construction and commissioning of a beamline and spectrometer for inelastic soft X-ray scattering at high resolution in a highly efficient system are presented. Based on the energy-compensation principle of grating dispersion, the design of the monochromator-spectrometer system greatly enhances the efficiency of measurement of inelastic soft X-rays scattering. Comprising two bendable gratings, the set-up effectively diminishes the defocus and coma aberrations. At commissioning, this system showed results of spin-flip, d-d and charge-transfer excitations of NiO. These results are consistent with published results but exhibit improved spectral resolution and increased efficiency of measurement. The best energy resolution of the set-up in terms of full width at half-maximum is 108 meV at an incident photon energy tuned about the Ni L3-edge.

Performance assessment of the single photon emission microscope: high spatial resolution SPECT imaging of small animal organs

The single photon emission microscope (SPEM) is an instrument developed to obtain high spatial resolution single photon emission computed tomography (SPECT) images of small structures inside the mouse brain. SPEM consists of two independent imaging devices, which combine a multipinhole collimator, a high-resolution, thallium-doped cesium iodide [CsI(Tl)] columnar scintillator, a demagnifying/intensifier tube, and an electron-multiplying charge-coupling device (CCD). Collimators have 300- and 450-µm diameter pinholes on tungsten slabs, in hexagonal arrays of 19 and 7 holes. Projection data are acquired in a photon-counting strategy, where CCD frames are stored at 50 frames per second, with a radius of rotation of 35 mm and magnification factor of one. The image reconstruction software tool is based on the maximum likelihood algorithm. Our aim was to evaluate the spatial resolution and sensitivity attainable with the seven-pinhole imaging device, together with the linearity for quantification on the tomographic images, and to test the instrument in obtaining tomographic images of different mouse organs. A spatial resolution better than 500 µm and a sensitivity of 21.6 counts·s^-1·MBq^-1 were reached, as well as a correlation coefficient between activity and intensity better than 0.99, when imaging ^99mTc sources. Images of the thyroid, heart, lungs, and bones of mice were registered using ^99mTc-labeled radiopharmaceuticals in times appropriate for routine preclinical experimentation of <1 h per projection data set. Detailed experimental protocols and images of the aforementioned organs are shown. We plan to extend the instrument's field of view to fix larger animals and to combine data from both detectors to reduce the acquisition time or applied activity.

Development of a Semiselective Medium for Detection of Nalanthamala psidii, Causal Agent of Wilt of Guava

Guava wilt, caused by Nalanthamala psidii, has become an important disease of guava (Psidium guajava) in Taiwan since the 1970s. This study was conducted to develop a semiselective medium for detecting N. psidii in soil and in tissues of diseased guava trees. Among 9 carbon and 21 nitrogen compounds tested in a modified Czapek-Dox medium, the most effective carbon and nitrogen sources for mycelial growth of N. psidii were sucrose and glycine, respectively. Among eight fungicides tested, iprodione at 5 μg ml^-1 and azoxystrobin at 1 μg ml^-1 were the most effective fungicides for detection of N. psidii in artificially infested soil or in naturally infected guava debris. Based on the requirement for carbon and nitrogen sources and response to fungicides, a semiselective medium designated as modified sucrose-glycine semiselective medium (mSGSSM) was developed for isolation of N. psidii, using the modified Czapek-Dox medium containing 3% sucrose, 0.3% glycine, iprodione at 5 μg ml^-1, azoxystrobin at 1 μg ml^-1, streptomycin at 200 μg ml^-1, and neomycin at 200 μg ml^-1. Colonies of N. psidii on mSGSSM at 30°C for 5 to 10 days were white to orange with sparse aerial hyphae. N. psidii was detected more accurately and efficiently on mSGSSM than on other media, including potato dextrose agar, modified Nash-Snyder medium, and modified Czapek-Dox medium. This semiselective medium is effective in detection of N. psidii from various parts of diseased guava trees and in soil; therefore, it would be a useful medium for etiological, ecological, and epidemiological studies of guava wilt.

Ferromagnetic interfacial interaction and the proximity effect in a Co2FeAl/(Ga,Mn)As bilayer

The magnetic properties of a Co2FeAl/(Ga,Mn)As bilayer epitaxied on GaAs (001) are studied both experimentally and theoretically. Unlike the common antiferromagnetic interfacial interaction existing in most ferromagnet-magnetic semiconductor bilayers, a ferromagnetic interfacial interaction in the Co2FeAl/(Ga,Mn)As bilayer is observed from measurements of magnetic hysteresis and x-ray magnetic circular dichroism. The Mn ions in a 1.36 nm thick (Ga,Mn)As layer remain spin polarized up to 400 K due to the magnetic proximity effect. The minor loops of the Co2FeAl/(Ga,Mn)As bilayer shift with a small ferromagnetic interaction field of +24 Oe and -23 Oe at 15 K. The observed ferromagnetic interfacial coupling is supported by ab initio density functional calculations. These findings may provide a viable pathway for designing room-temperature semiconductor spintronic devices through magnetic proximity effect.

Orthorhombic BiFeO3

A new orthorhombic phase of the multiferroic BiFeO3 has been created via strain engineering by growing it on a NdScO(3)(110)(o) substrate. The tensile-strained orthorhombic BiFeO3 phase is ferroelectric and antiferromagnetic at room temperature. A combination of nonlinear optical second harmonic generation and piezoresponse force microscopy revealed that the ferroelectric polarization in the orthorhombic phase is along the in-plane {110}(pc) directions. In addition, the corresponding rotation of the antiferromagnetic axis in this new phase was observed using x-ray linear dichroism.

Differential time dependency of antiproliferative and apoptotic effects of taxol in human prostate tumors

The pharmacodynamics of taxol in human prostate tumors were studied using histocultures of radical prostatectomy specimens from 34 patients. The results showed that taxol inhibited DNA synthesis and induced apoptosis in all tumors. The taxol-induced DNA inhibition and the apoptotic index increased with drug concentration, but reached a maximal plateau level at a concentration between 120 and 1,200 nM. Increasing the concentration by 10- to 100-fold to 12,000 nM did not significantly increase either effect. To address the existing controversy regarding the effect of treatment duration on cytotoxicity, we evaluated two treatment schedules, (i.e., 24 and 96 hours). Prolonging the treatment time from 24 to 96 hours significantly increased the average maximal inhibition of DNA synthesis (E(max)) from 47% to 70% (p < 0.001) and reduced the incidence of relatively resistant tumors (E(max) < 30%) from 31% to 0% (p = 0.04). By contrast, the prolonged treatment time did not increase the apoptotic effect (p = 0.48). The inter-tumor variation in sensitivity to the antiproliferative effect was substantial; the drug concentration required to produce a 30% DNA inhibition (IC(30)) showed a >300,000- and a 14,000-fold range for the 24 and 96 hour treatments, respectively. In conclusion, data of the present study demonstrate (1) antiproliferative and apoptotic effects of taxol in human prostate tumors, (2) that neither effect was significantly enhanced by increasing the drug concentration above 1,200 nM, and (3) that the antiproliferative effect was affected more significantly by drug exposure time than the apoptotic effect.

First imaging result with an ultrahigh resolution stationary MR compatible SPECT system

In this paper, we will present the design and preliminary performance of an ultrahigh resolution stationary MR compatible SPECT (MRC-SPECT) system that is developed in our lab. The MRC-SPECT system is based on the second-generation energy-resolved photon-counting (ERPC) CdTe detectors and there are several key features associated with this system. Firstly, up to a total of twenty ERPC detectors will be assembled as a very compact ring, which provides an adequate angular sampling capability and a relatively high detection efficiency. The detectors are supported on a gantry made of high strength polyamide structure constructed using 3-D printing. This compact system can be directly operated inside an MR scanner. The detector module used in this system offers an intrinsic resolution of 350μm and an excellent energy resolution of around 3~4kev. Each ERPC detector module consists of four pixelated CdTe detectors with a total dimension of 4.5cm×2.25cm. Secondly, a die-cast platinum pinhole inserts and cast lead apertures are developed for this stationary SPECT system. Four 300/500μm diameter pinholes are used for each detector and all pinholes are mounted around a casted cylinder lead aperture tube. The inner diameter of the lead aperture tube is 6cm and the lead tube thickness is 16mm. The opposite detectors are placed 15.6cm apart and the magnification factor of this SPECT system is about 1.2. Thirdly, a comprehensive charge collection model inside strong magnetic field has been developed to account for the magnetic field induced distortion in the SPECT image. This model can accurately predict the detector's energy and spatial response to gamma ray incident events and then help to compensate for the event position recording error due to the strong magnetic field. In this development, we have made an effort to minimize the amount of magnetic materials in the system to alleviate potential interference to magnetic field inhomogeneity.

Ab initio studies on the optical effects in the deep ultraviolet nonlinear optical crystals of the KBe2BO3F2 family

Electronic structures of the deep ultraviolet nonlinear optical crystals of the KBe(2)BO(3)F(2) (KBBF) family, including KBBF, RbBe(2)BO(3)F(2) and CsBe(2)BO(3)F(2), have been investigated based on a plane-wave pseudopotential method. Their linear and nonlinear optical coefficients are also calculated, and are in good agreement with the experimental results. A real-space atom-cutting method is adopted to analyze the respective contributions of the alkali metal cations and anionic groups to optical response. The results show that the contributions of anionic groups to the nonlinear optical anisotropic responses are dominant, but the influence of the A-site alkali metal cations becomes slightly more pronounced with the increase of their radius. Moreover, the birefringence difference among these crystals strongly depends on the volume effect, i.e., the spatial density of the (BO(3))(3-) anionic groups.

Inhibitory Effects of Chinese Medicinal Herbs on Plant-Pathogenic Bacteria and Identification of the Active Components from Gallnuts of Chinese Sumac

The aqueous extracts of 30 out of 67 Chinese medicinal herbs were shown to have inhibitory effects on growth of Xanthomonas euvesicatoria by a paper disc diffusion assay. The inhibitory substances with the strongest antibacterial activity were extracted from Chinese sumac gallnut and black myrobalan. The aqueous extract of gallnut inhibited the growth of eight of the tested plant-pathogenic bacteria, and that of black myrobalan inhibited five. The gallnut extract produced at least an 8-mm inhibition zone against Acidovorax citrulli, Ralstonia solanacearum, X. citri pv. citri, and X. euvesicatoria at a 10-fold dilution, and it was still active at 800- to 1,600-fold dilutions. The aqueous extract of gallnut was more inhibitory than the acetone-water extract. To identify the inhibitory compounds in the gallnut aqueous extract, the crude extract was chromatographed over a silica column, and the primary compounds in fractions 3 and 8 were identified by nuclear magnetic resonance as gallic acid and methyl gallate, respectively. The inhibitory effect of methyl gallate on the growth of four plant-pathogenic bacteria was 10 to 80 times that of gallic acid. The minimum inhibition and minimum bactericidal concentration tests showed that the inhibition effect of the original aqueous was higher than that of methyl gallate. These results indicate that methyl gallate in gallnut is an important compound that is inhibitory to plant-pathogenic bacterial growth, and there are other unidentified compounds that are also responsible for the antibacterial effects. This is the first report regarding the antibacterial effects of gallnut extract and its chemical components on plant-pathogenic bacteria.

Energy band gap engineering in borate ultraviolet nonlinear optical crystals: ab initio studies

The development of ultraviolet (UV) nonlinear optical (NLO) crystals demands optical materials with wide energy band gaps. Here we report first-principles studies on the electronic structures in several UV NLO borates with representative structures. Combined with model analysis, we find that the oxygen non-bonding 2p orbitals play an important role on the top of valence bands. The energy band gap can be adjusted by modifying the coordination environment around the oxygen atoms. Under ideal conditions the energy band gaps achieve 9 eV if the non-bonding orbitals are totally eliminated, despite the original values varying from 6.6 to 8.3 eV.

L-arginine trifluoroacetate salt bridges in its solid state compound: the low-temperature three dimensional structural determination of L-arginine bis(trifluoroacetate) crystal and its vibrational spectral analysis

Structural varieties of L-arginine trifluoroacetate (abbreviated as LATF) and L-arginine bis(trifluoroacetate), LABTF, in the solid state compounds were observed and analyzed by the nuclear magnetic resonance (NMR) spectroscopy. The guanidinium-carboxylate interaction plays an important role involving in the crystal structure construction. Conformational changes of L-Arg(+) and L-Arg(2+) cations result from the intrinsic structural difference by hydrogen bonding and electrostatic interactions. The low-temperature structure of its crystalline salt, L-arginine bis(trifluoroacetate), was determined to describe the hydrogen bonding interactions. In comparison with the crystal structure at room temperature, the low-temperature L-Arg(2+) cations present tiny conformational difference and the rotational disorder of CF(3) group disappears. FT-IR and Raman spectra were investigated and hydrogen bonding interactions were analyzed on the basis of its vibrational spectra. Results indicate that this type interaction is greatly contributive to the structural features and vibrational spectral properties.

Mechanical Loading of Articular Cartilage Reduces IL-1-Induced Enzyme Expression

OBJECTIVE: Exposure of articular cartilage to interleukin-1 (IL-1) results in increased synthesis of matrix degrading enzymes. Previously mechanical load applied together with IL-1 stimulation was found to reduce aggrecan cleavage by ADAMTS-4 and 5 and MMP-1, -3, -9, and -13 and reduce proteoglycan loss from the extracellular matrix. To further delineate the inhibition mechanism the gene expression of ADAMTS-4 and 5; MMP-1, -3, -9, and -13; and TIMP-1, -2, and -3 were measured. DESIGN: Mature bovine articular cartilage was stimulated with a 0.5 MPa compressive stress and 10 ng/ml of IL-1α for 3 days and then allowed to recover without stimulation for 1 additional day. The media was assayed for proteoglycan content on a daily basis, while chondrocyte gene expression (mRNA) was measured during stimulation and 1 day of recovery. RESULTS: Mechanical load alone did not change the gene expression for ADAMTS, MMP, or TIMP. IL-1 caused an increase in gene expression for all enzymes after 1 day of stimulation while not affecting the TIMP levels. Load applied together with IL-1 decreased the expression levels of ADAMTS-4 and -5 and MMP-1 and -3 and increased TIMP-3 expression. CONCLUSIONS: A mechanical load appears to modify cartilage degradation by IL-1 at the cellular level by reducing mRNA.

Microscopic origin of the giant ferroelectric polarization in tetragonal-like BiFeO(3)

We report direct experimental evidence for a room-temperature, ∼130  μC/cm(2) ferroelectric polarization from the tetragonal-like BiFeO(3) phase. The physical origin of this remarkable enhancement of ferroelectric polarization has been investigated by a combination of x-ray absorption spectroscopy, scanning transmission electron microscopy, and first principles calculations. A large strain-induced Fe-ion displacement relative to the oxygen octahedra, combined with the contribution of Bi 6s lone pair electrons, is the mechanism driving the large ferroelectric polarization in this tetragonal-like phase.

Determination of the Co valence in bilayer hydrated superconducting NaxCoO2 · yH2O by soft x-ray absorption spectroscopy

We addressed the so-far unresolved issue concerning the Co valence in the superconducting bilayer hydrated Na(x)CoO(2) · yH(2)O (x∼0.35, y∼1.3) using soft x-ray absorption spectroscopy at the Co-L(2,3) and O-K edges. We find that the valence state of the Co lies in a narrow range from +3.3 to +3.4 for all studied Na(x)CoO(2) · yH(2)O samples and their deuterated analogue with T(c)'s ranging from 3.8 to 4.7 K. These valence values are far from the often claimed +3.7, the number based on the Na content only. We propose to modify the phase diagram accordingly, where the basic electronic structure of the superconducting phase is very close to that of the Na(0.7)CoO(2) system, suggesting that the presence of in-plane spin fluctuations could play an important role for the superconductivity.

Effect of co-doping of donor and acceptor impurities in the ferromagnetic semiconductor Zn(1-x)Cr(x)Te studied by soft x-ray magnetic circular dichroism

We have performed x-ray absorption spectroscopy (XAS) and x-ray magnetic circular dichroism (XMCD) studies of the diluted ferromagnetic semiconductor Zn(1-x)Cr(x)Te doped with iodine (I) or nitrogen (N), corresponding to electron or hole doping, respectively. From the shape of the Cr 2p absorption peak in the XAS spectra, it was concluded that the Cr ions in the undoped, I-doped and lightly N-doped samples are divalent (Cr(2+)), while Cr(2+) and trivalent (Cr(3+)) coexist in the heavily N-doped sample. This result indicates that the doped nitrogen atoms act as acceptors but that doped holes are located on the Cr ions. In the magnetic field dependence of the XMCD signal at the Cr 2p absorption edge, ferromagnetic behaviors were observed in the undoped, I-doped, and lightly N-doped samples, while ferromagnetism was considerably suppressed in the heavily N-doped sample, which is consistent with the results of magnetization measurements.

Bulk and surface magnetization of Co atoms in rutile Ti(1-x)Co(x)O(2-δ) thin films revealed by x-ray magnetic circular dichroism

We have studied magnetism in Ti(1-x)Co(x)O(2-δ) thin films with various x and δ by soft x-ray magnetic circular dichroism (XMCD) measurements at the Co L(2, 3) absorption edges. The estimated ferromagnetic moment by XMCD was 0.15-0.24 µ(B)/Co at the surface, while in the bulk it was 0.82-2.25 µ(B)/Co, which is in the same range as the saturation magnetization of 1.0-1.5 µ(B)/Co. These results suggest an intrinsic origin of the ferromagnetism. The smaller moment of the Co atom at the surface is an indication of a magnetically dead layer of a few nanometers thick at the surface of the thin films.

Development of the sediment and water quality management strategies for the Salt-water River, Taiwan

The Salt-water River watershed is one of the major river watersheds in the Kaohsiung City, Taiwan. Water quality and sediment investigation results show that the river water contained high concentrations of organics and ammonia-nitrogen, and sediments contained high concentrations of heavy metals and organic contaminants. The main pollution sources were municipal and industrial wastewaters. Results from the enrichment factor (EF) and geo-accumulation index (Igeo) analyses imply that the sediments can be characterized as heavily polluted in regard to Cd, Cr, Pb, Zn, and Cu. The water quality analysis simulation program (WASP) model was applied for water quality evaluation and carrying capacity calculation. Modeling results show that the daily pollutant inputs were much higher than the calculated carrying capacity (1050 kg day(-1) for biochemical oxygen demand and 420 kg day(-1) for ammonia-nitrogen). The proposed watershed management strategies included river water dilution, intercepting sewer system construction and sediment dredging.

Toluidine blue O photodynamic inactivation on multidrug-resistant Pseudomonas aeruginosa

BACKGROUND AND OBJECTIVES

Multidrug-resistant (MDR) Pseudomonas aeruginosa infection is becoming a critical problem worldwide. Currently, only limited therapeutic options are available for the treatment of infections caused by MDR P. aeruginosa, therefore, the development of new alternative treatments is needed. Toluidine blue O (TBO) is an effective antibacterial photosensitizing agent against various bacteria. However, reports on antibacterial photosensitization of MDR bacteria are limited. This study aims to determine the in vitro photobactericidal activity of TBO against MDR P. aeruginosa.

STUDY DESIGN/MATERIALS AND METHODS

The efficacy of antibacterial photodynamic inactivation, DNA fragmentation and protein carbonylation of three MDR P. aeruginosa strains and one susceptible strain was compared using TBO as the photosensitizer followed by red light irradiation (630 nm, 90 J/cm(2)) from a light-emitting diode light source. Subsequently, the efficacy of TBO photodynamic inactivation (TBO-PDI) on 60 MDR strains, including 11 with the efflux pump phenotype and 49 with no pump activity, was tested using the minimum lethal drug concentration (MLC) assay.

RESULTS

TBO-PDI caused similar bactericidal effect (6-7 logs of killing effect), DNA fragmentation and protein carbonylation in three MDR and one susceptible P. aeruginosa strains. Although the TBO accumulation assay indicated that TBO is a substrate for the efflux pump, TBO-PDI produce similar photobactericidal activity against 60 MDR P. aeruginosa strains, either with or without efflux-pump phenotype, and 19 susceptible strains.

CONCLUSION

MDR did not affect the susceptibility of P. aeruginosa strains to TBO-PDI. The efflux pump played an insignificant role in TBO-PDI of MDR P. aeruginosa.

A Multi-Threshold Sampling Method for TOF PET Signal Processing

As an approach to realizing all-digital data acquisition for positron emission tomography (PET), we have previously proposed and studied a multi-threshold sampling method to generate samples of a PET event waveform with respect to a few user-defined amplitudes. In this sampling scheme, one can extract both the energy and timing information for an event. In this paper, we report our prototype implementation of this sampling method and the performance results obtained with this prototype. The prototype consists of two multi-threshold discriminator boards and a time-to-digital converter (TDC) board. Each of the multi-threshold discriminator boards takes one input and provides up to 8 threshold levels, which can be defined by users, for sampling the input signal. The TDC board employs the CERN HPTDC chip that determines the digitized times of the leading and falling edges of the discriminator output pulses. We connect our prototype electronics to the outputs of two Hamamatsu R9800 photomultiplier tubes (PMTs) that are individually coupled to a 6.25×6.25×25mm(3) LSO crystal. By analyzing waveform samples generated by using four thresholds, we obtain a coincidence timing resolution of about 340 ps and an ∼18% energy resolution at 511 keV. We are also able to estimate the decay-time constant from the resulting samples and obtain a mean value of 44ns with an ∼9 ns FWHM. In comparison, using digitized waveforms obtained at a 20 GSps sampling rate for the same LSO/PMT modules we obtain ∼300 ps coincidence timing resolution, ∼14% energy resolution at 511 keV, and ∼5 ns FWHM for the estimated decay-time constant. Details of the results on the timing and energy resolutions by using the multi-threshold method indicate that it is a promising approach for implementing digital PET data acquisition.

Spin blockade, orbital occupation, and charge ordering in La1.5Sr0.5CoO4

Using Co-L2,3 and O-K x-ray absorption spectroscopy, we reveal that the charge ordering in La1.5Sr0.5CoO4 involves high spin (S=3/2) Co2+ and low spin (S=0) Co3+ ions. This provides evidence for the spin-blockade phenomenon as a source for the extremely insulating nature of the La2-xSrxCoO4 series. The associated e{g}{2} and e{g}{0} orbital occupation accounts for the large contrast in the Co-O bond lengths and, in turn, the high charge ordering temperature. Yet, the low magnetic ordering temperature is naturally explained by the presence of the nonmagnetic (S=0) Co3+ ions. From the identification of the bands we infer that La1.5Sr0.5CoO4 is a narrow band material.

An Ultrahigh Resolution SPECT System for I-125 Mouse Brain Imaging Studies

This paper presents some initial experimental results obtained with a dual-head prototype single photon emission microscope system (SPEM) that is dedicated to mouse brain studies using I-125 labeled radiotracers. In particular, this system will be used for in vivo tacking of radiolabeled T cells in mouse brain. This system is based on the use of the intensified electron multiplying charge-coupled device (I-EMCCD) camera that offers the combination of an excellent intrinsic spatial resolution, a good signal-to-noise ratio, a large active area and a reasonable detection efficiency over an energy range between 27-140keV. In this study, the dual-head SPEM system was evaluated using both resolution phantoms and a mouse with locally injected T cells labelled with I-125. It was demonstrated that for a relatively concentrated source object, the current dual-head SPEM system is capable of visualizing the tiny amount of radioactivity (~12 nCi) carried by a very small number (<1000) of T cells. The current SPEM system design allows four or six camera heads to be installed in a stationary system configuration that offers a doubled or tripled sensitivity at a spatial resolution similar to that obtained with the dualhead system. This development would provide a powerful tool for in vivo and non-invasive tracking of radiolabeled T cells in mouse brain and potentially for other rodent brain imaging studies.

Thermally or magnetically induced polarization reversal in the Multiferroic CoCr2O4

We report the unexpected evolution, with thermal and magnetic-field (H) variations, of the interrelation between the polarization P, magnetization M, and spiral wave vector Q in CoCr2O4, which has a ferrimagnetic conical-spiral magnetic order. For example, P suddenly jumps and changes its sign at the magnetic lock-in transition (T_{L}) with thermal variation, or with isothermal variation of H (without changing its direction) at T_{L}, which surprisingly occurs without change in spiral handedness (i.e., the sign of Q). The presence of multiple spiral sublattices may be behind this unusual behavior.

Mass Spectrometry in Microbial Forensics

Mass spectrometry (MS) has become a powerful tool to identify microbial biomarkers. Rapid and reliable identification of microorganisms by MS without extensive sample pretreatment is now possible. An effective microbial forensics program requires accurate characterization of pathogens to indicate their presence. MS methods provide such capabilities for forensic analysis. MS methods currently utilized for microbial analyses are reviewed. Techniques including capillary electrophoresis, liquid chromatography, gas chromatography, and pyrolysis that are coupled to MS analysis are described. A brief introduction to the two advanced ionization techniques, electrospray ionization and matrix-assisted laser desorption/ionization, for MS is provided in this review. Methods based on characterization of biomarkers including proteins, DNA molecules, lipids, and other small molecules are reviewed.

Magnetic ground state and transition of a quantum multiferroic LiCu2O2

Based on resonant soft x-ray magnetic scattering, we report that LiCu2O2 exhibits a large interchain coupling which suppresses quantum fluctuations along spin chains, and a quasi-2D short-range magnetic order prevails at temperatures above the magnetic transition. These observations unravel the fact that the ground state of LiCu2O2 possesses long-range 2D-like incommensurate magnetic order rather than being a gapped spin liquid as expected from the nature of quantum spin-1/2 chains. In addition, the spin coupling along the c axis is found to be essential for inducing electric polarization.

Crystal-field level inversion in lightly Mn-doped Sr3Ru2O7

Sr3(Ru(1-x)Mnx)2O7, in which 4d-Ru is substituted by the more localized 3d-Mn, is studied by x-ray dichroism and spin-resolved density functional theory. We find that Mn impurities do not exhibit the same 4+ valence of Ru, but act as 3+ acceptors; the extra eg electron occupies the in-plane 3d(x2-y2) orbital instead of the expected out-of-plane 3d(3z2-r2). We propose that the 3d-4d interplay, via the ligand oxygen orbitals, is responsible for this crystal-field level inversion and the material's transition to an antiferromagnetic, possibly orbitally ordered, low-temperature state.

Determining the crystal-field ground state in rare earth heavy fermion materials using soft-x-ray absorption spectroscopy

We infer that soft-x-ray absorption spectroscopy is a versatile method for the determination of the crystal-field ground state symmetry of rare earth heavy fermion systems, complementing neutron scattering. Using realistic and universal parameters, we provide a theoretical mapping between the polarization dependence of Ce M(4,5) spectra and the charge distribution of the Ce 4f states. The experimental resolution can be orders of magnitude larger than the 4f crystal-field splitting itself. To demonstrate the experimental feasibility of the method, we investigated CePd2Si2, thereby settling an existing disagreement about its crystal-field ground state.

High-average-power light source below 200 nm from a KBe(2)BO(3)F(2) prism-coupled device

Using a 2.3 mm thick KBe(2)BO(3)F(2) crystal optically contacted with CaF(2) in a prism-coupled device, we have obtained an average output power of as much as 360 mW at 200 nm. Long-term stability was verified above a 150 mW level at 200 nm. An output power of 50 mW was also obtained with a narrow spectral width of 0.007 pm at 193.5 nm.