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.

The impact and recovery of asteroid 2008 TC(3)

In the absence of a firm link between individual meteorites and their asteroidal parent bodies, asteroids are typically characterized only by their light reflection properties, and grouped accordingly into classes. On 6 October 2008, a small asteroid was discovered with a flat reflectance spectrum in the 554-995 nm wavelength range, and designated 2008 TC(3) (refs 4-6). It subsequently hit the Earth. Because it exploded at 37 km altitude, no macroscopic fragments were expected to survive. Here we report that a dedicated search along the approach trajectory recovered 47 meteorites, fragments of a single body named Almahata Sitta, with a total mass of 3.95 kg. Analysis of one of these meteorites shows it to be an achondrite, a polymict ureilite, anomalous in its class: ultra-fine-grained and porous, with large carbonaceous grains. The combined asteroid and meteorite reflectance spectra identify the asteroid as F class, now firmly linked to dark carbon-rich anomalous ureilites, a material so fragile it was not previously represented in meteorite collections.

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.

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.

Magnetizing oxides by substituting nitrogen for oxygen

We describe a possible pathway to new magnetic materials with no conventional magnetic elements present. The substitution of nitrogen for oxygen in simple nonmagnetic oxides leads to holes in N 2p states which form local magnetic moments. Because of the very large Hund's rule coupling of Nitrogen and O 2p electrons and the rather extended spatial extent of the wave functions these materials are predicted to be ferromagnetic metals or small band gap insulators. Experimental studies support the theoretical calculations with regard to the basic electronic structure and the formation of local magnetic moments. It remains to be seen if these materials are magnetically ordered and, if so, below what temperature.

Spin state transition in LaCoO3 studied using soft x-ray absorption spectroscopy and magnetic circular dichroism

Using soft x-ray absorption spectroscopy and magnetic circular dichroism at the Co-L(2,3) edge, we reveal that the spin state transition in LaCoO3 can be well described by a low-spin ground state and a triply degenerate high-spin first excited state. From the temperature dependence of the spectral line shapes, we find that LaCoO3 at finite temperatures is an inhomogeneous mixed-spin state system. It is crucial that the magnetic circular dichroism signal in the paramagnetic state carries a large orbital momentum. This directly shows that the currently accepted low- or intermediate-spin picture is at variance. Parameters derived from these spectroscopies fully explain existing magnetic susceptibility, electron spin resonance, and inelastic neutron data.

Transfer of spectral weight and symmetry across the metal-insulator transition in VO(2)

We present a detailed study of the valence and conduction bands of VO2 across the metal-insulator transition using bulk-sensitive photoelectron and O K x-ray absorption spectroscopies. We observe a giant transfer of spectral weight with distinct features that require an explanation which goes beyond the Peierls transition model as well as the standard single-band Hubbard model. Analysis of the symmetry and energies of the bands reveals the decisive role of the V 3d orbital degrees of freedom. Comparison to recent realistic many body calculations shows that much of the k dependence of the self-energy correction can be cast within a dimer model.

Orbitally driven spin-singlet dimerization in S=1 La4Ru2O10

Using x-ray absorption spectroscopy at the Ru-L2,3 edge we reveal that the Ru4+ ions remain in the S=1 spin state across the rare 4d-orbital ordering transition and spin-gap formation. We find using local spin density approximation + Hubbard U band structure calculations that the crystal fields in the low-temperature phase are not strong enough to stabilize the S=0 state. Instead, we identify a distinct orbital ordering with a significant anisotropy of the antiferromagnetic exchange couplings. We conclude that La4Ru2O10 appears to be a novel material in which the orbital physics drives the formation of spin-singlet dimers in a quasi-two-dimensional S=1 system.

Orbital-assisted metal-insulator transition in VO2

We found direct experimental evidence for an orbital switching in the V 3d states across the metal-insulator transition in VO2. We have used soft-x-ray absorption spectroscopy at the V L2,3 edges as a sensitive local probe and have determined quantitatively the orbital polarizations. These results strongly suggest that, in going from the metallic to the insulating state, the orbital occupation changes in a manner that charge fluctuations and effective bandwidths are reduced, that the system becomes more one dimensional and more susceptible to a Peierls-like transition, and that the required massive orbital switching can only be made if the system is close to a Mott insulating regime.

Controlling orbital moment and spin orientation in CoO layers by strain

We have observed that CoO films grown on different substrates show dramatic differences in their magnetic properties. Using polarization dependent x-ray absorption spectroscopy at the Co L2,3 edges, we revealed that the magnitude and orientation of the magnetic moments strongly depend on the strain in the films induced by the substrate. We presented a quantitative model to explain how strain together with the spin-orbit interaction determine the 3d orbital occupation, the magnetic anisotropy, as well as the spin and orbital contributions to the magnetic moments. Control over the sign and direction of the strain may, therefore, open new opportunities for applications in the field of exchange bias in multilayered magnetic films.

Determination of the orbital moment and crystal-field splitting in LaTiO3

Utilizing a sum rule in a spin-resolved photoelectron spectroscopic experiment with circularly polarized light, we show that the orbital moment in LaTiO3 is strongly reduced from its ionic value, both below and above the Ne el temperature. Using Ti L2,3 x-ray absorption spectroscopy as a local probe, we found that the crystal-field splitting in the t2g subshell is about 0.12-0.30 eV. This large splitting does not facilitate the formation of an orbital liquid.

Different look at the spin state of Co(3+) ions in a CoO(5) pyramidal coordination

Using soft-x-ray absorption spectroscopy at the Co L(2,3) and O K edges, we demonstrate that the Co3+ ions with the CoO5 pyramidal coordination in the layered Sr2CoO3Cl compound are unambiguously in the high spin state. Our result questions the reliability of the spin state assignments made so far for the recently synthesized layered cobalt perovskites and calls for a reexamination of the modeling for the complex and fascinating properties of these new materials.

Magnetic dichroism and spin structure of antiferromagnetic NiO(001) films

We find that Ni L2 edge x-ray magnetic linear dichroism is fully reversed for NiO(001) films on materials with reversed lattice mismatch. We relate this phenomenon to a preferential stabilization of magnetic S domains with main spin component either in or out of the plane, via dipolar interactions. This suggests a way to selectively control spin structures in 3d systems with small spin-orbit coupling.

Emphysematous pyelonephritis in a renal allograft: successful treatment with percutaneous drainage and nephrostomy

Emphysematous pyelonephritis in renal transplant allograft occurs rarely. This is a case report on a 55-year-old man who had renal transplantation in 1983 and developed post-transplant diabetes mellitus in 1984. This patient suffered from fever and right low abdominal pain and was subsequently diagnosed as emphysematous pyelonephritis by computerized tomography. He was successfully treated with percutaneous drainage, percutaneous nephrostomy and parenteral antibiotics. Although the management of emphysematous pyelonephritis has been a subject of controversy, we recommend consideration of renal preservation in patients with few risk factors, especially in those patients presenting with chronic renal insufficiency, solitary kidney and transplant allograft.

Risk factors for renal allograft survival in patients receiving cyclosporine immunosuppression

BACKGROUND AND PURPOSE

Although cyclosporine (CsA) has been widely used in renal transplantation for more than 10 years, no large series of renal transplant patients has been studied in southern Taiwan. The purpose of this retrospective cohort study was to investigate the risk factors for graft survival in renal transplant recipients.

METHODS

From August 1987 to January 1998, 101 primary cadaveric renal transplantations were performed. The minimum follow-up period was 1 year. CsA and prednisolone were initially used as immunosuppressive agents in all patients. Use of lower doses of CsA to reduce CsA trough level (50-99 ng/mL) in hepatitis B surface antigen (HBsAg)-positive recipients was attempted at 6 months after transplantation.

RESULTS

Graft actuarial survival rates at 1, 5, and 10 years posttransplantation were 89%, 75%, and 57%, respectively. Acute rejection and increased recipient age were found to be significant risk factors (p < 0.05) affecting graft survival, with hazard ratios of 5.20 and 1.74, respectively, by multivariate analysis using a Cox proportional hazards model. Hepatitis B and/or hepatitis C infection had no influence on graft survival.

CONCLUSIONS

In this series of cadaveric renal allograft patients, the risk factors affecting allograft survival were acute rejection and recipient age.

Retroperitoneoscopic ureterolithotomy for impacted ureteral stones

BACKGROUND

Despite the fact that extracorporeal shock wave lithotripsy and endourological procedures have greatly diminished the need for open ureterolithotomy, invasive open surgery is still necessary in some cases of obstinate ureteral stones when less invasive methods fail. Since Wickham first performed a retroperitoneoscopic ureterolithotomy in 1979, procedures which are less invasive than open ureterolithotomy have been available in some selected cases.

METHODS

In 1997, retroperitoneoscopic ureterolithotomy was performed in 5 patients with ureteral stones, in whom treatment with other minimally invasive procedures had failed. Using Gaur's technique of balloon dissection of the retroperitoneal space, retroperitoneoscopic ureterolithotomy was successfully performed in all cases.

RESULTS

All the patients were treated successfully with the retroperitoneoscopic maneuver. The average operating time was 125 (90 to 175) minutes, and the average blood loss was 75 (20 to 200) ml. No patient required an analgesic injection postoperatively. The average postoperative hospital stay was 5.5 (4 to 8) days, and there were no immediate operative complications in any case. Patients were followed an average of 18.5 (13 to 24) months. A ureteral stricture developed in one patient and was resolved by ureteroureterostomy 3 months after the first operation.

CONCLUSION

As an impacted ureteral stone is always associated with chronic ureteritis, firmness and adhesion of the periureteral tissue make the retroperitoneoscopic procedure difficult. In one case, a late complication of ureteral stricture may have been due to pre-existing severe chronic inflammation. Based on our limited experience, retroperitoneoscopic ureterolithotomy provides a practical alternative for the management of ureteral stones in selected patients. An expert clinician with experience in this procedure will provide the best results.

Help-seeking behaviors in relatives of schizophrenics in Taiwan

Despite its merits, the Western-style psychiatric community rehabilitation model is not well accepted by caregivers in Taiwan. We examined factors affecting the utilization of community rehabilitation programs in Taiwan. Our stepwise logistic regression revealed that psychoeducation regarding the biological cause of schizophrenia emerged as the major factor for increasing utilization treatment modality. Eighty-nine pairs of schizophrenic patients (who had been recommended for rehabilitation) and their relatives were divided into two groups, the rehabilitation group and the nonrehabilitation group. Both groups were surveyed on help-seeking behavior scales and mental function measurements. The results showed no significant differences in patients' psychopathology, though the rehabilitation group had higher employment rates. As for caregivers, the rehabilitation group scored significantly better on some cognitive appraisals, whereas the nonrehabilitation group was more inclined to institutionalize the patients for life. No significant differences were noticed on rejection attitude, subjective care burden, or expressed emotion measures. Improving caregiver's knowledge about the disease, providing activities that lend emotional, physical, and financial support and thereby reduce the burden and increase the satisfaction of caregivers may be useful. Besides making the Western-style psychiatric community rehabilitation model more effective and accessible for patients and caregivers in Taiwan, cultural adaptation is also needed.

Renal squamous cell carcinoma: CT findings and clinical significance

BACKGROUND

To study the biological behavior of renal squamous cell carcinoma (RSCC).

METHODS

Fifteen cases of RSCC were retrospectively studied. These cases were classified as central (eight cases) and peripheral (seven cases) types by the tumor location. The clinical data and computed tomographic findings were analyzed and compared.

RESULTS

High incidence (87%) of urolithiasis was observed. The prognosis of RSCC was very poor, with a median survival time of 3.5 months. The infectious symptoms, central location, and modified stage IV of the tumor were the poor prognostic factors of RSCC. Two types of RSCC were different in the presenting symptoms, lymph node metastasis, modified tumor staging, and survival time.

CONCLUSION

The central and peripheral types of RSCC were different biologically. High index of suspicion should be maintained when identifying the subtle clues of malignancy in patients with urolithiasis.

Unusual imaging presentations in renal transitional cell carcinoma

PURPOSE

To report on unusual imaging presentations in renal transitional cell carcinoma (TCC).

MATERIAL AND METHODS

Imaging studies of 140 cases of pathologically proven renal TCC were retrospectively studied with the focus on unusual presentations.

RESULTS

Unusual imaging manifestations were found in 20 cases (14.3%). These findings were classified into 5 categories: perirenal abscesses or perirenal hematomas in 6 cases; parenchymal masses in 5; undue thickening of the hydronephrotic wall in 4; "tuberculoid" pyelograms in 3; and tumors with massive necrosis in 2.

CONCLUSION

Deceptive imaging presentations may occur in renal TCC. Recognition of these presentations may help to prevent delay in diagnosis.

Vegetable consumption, serum retinol level, and risk of hepatocellular carcinoma

A cohort of 8436 men in Taiwan was recruited with personal interview and blood sample collection between 1984 and 1986. During the 5-year follow-up period, 50 incident cases of hepatocellular carcinoma (HCC) were identified. Retinol levels were measured for 35 HCC patients whose serum samples were available and 140 matched controls randomly selected from cohort members without HCC. Lower vegetable intake was significantly associated with an increased risk of HCC after adjustment for other HCC risk factors (P = 0.006). The effect of low vegetable intake on HCC risk was limited to hepatitis B virus chronic carriers and cigarette smokers. As compared with subjects who had a weekly vegetable consumption frequency of six or more meals, the multivariate-adjusted relative risk of HCC for subjects who had a frequency of less than six meals was 4.7 (95% confidence interval, 2.0-11.1; P = 0.0004) among chronic hepatitis B virus carriers and 3.8 (95% confidence interval, 1.7-8.5; P = 0.001) among cigarette smokers. There was an inverse dose-response relationship between the prediagnostic serum retinol level and the development of HCC (trend test, P = 0.003). The odds ratio of HCC for men with a retinol level in the lowest tertile was 9.0 (95% confidence interval, 2.1-39.1) compared with those with a level in the highest tertile. The relation remained after multivariate adjustment for cigarette smoking, habitual alcohol drinking, and either the seropositivity of hepatitis B virus surface antigen and/or anti-hepatitis C virus antibody or the past history of liver diseases through conditional logistic regression analysis. The association was more striking for men 55 years or younger and for those who smoked 10 or more cigarettes/day. There was a significant synergistic effect of hepatitis B virus surface antigen carrier status and low serum retinol level on the development of HCC. These data suggest a potential role of retinol in the chemoprevention of HCC.

Choriocarcinoma presenting as a unilateral renal mass and gross hematuria in a male: report of a case

Choriocarcinoma of the kidney, either primary or metastatic, is rarely reported in the literature. We encountered a male patient with choriocarcinoma of the right kidney. The patient initially presented with fever, gross hematuria and flank pain. He had initially been unsuccessfully treated for bilateral renal stones for four months before an accurate diagnosis was made. The disease was verified only after a resection of the right kidney and meticulous examination of microscopic sections of the tumor. Further immunohistochemical study strongly supported the diagnosis of choriocarcinoma. The tumor responded briefly to Cisplatinum, Vinblastine and Bleomycin (PVB) treatment. The patient died of brain metastasis and respiratory failure four months after starting systemic chemotherapy.

Methotrexate, vinblastine, adriamycin and cisplatin (M-VAC) for advanced TCC of urothelium

After the introduction of methotrexate, vinblastine, adriamycin and cisplatin combination (M-VAC) chemotherapy for transitional cell carcinoma (TCC) of the urothelium, the reported response and survival rates improved when compared with the previous regimens. From July 1989 to March 1991, 43 consecutive cases of invasive or metastatic TCC that had received at least one course of M-VAC treatment were collected by a computer-assisted search and analyzed. The overall response rate, including complete response (CR) and partial response (PR), was 44% (CR, 16%; PR, 28%). Tumors originating from the renal pelvis or bladder responded better than those from the ureter (kidney, 57%; bladder, 42%; and ureter 30%). Lymph node, soft tissue, lung metastases and local recurrent tumors had a greater chance of response than bone or liver metastases. Although patients from the blackfoot disease endemic area seemed to respond better than those from the nonendemic area, there was no statistically significant survival benefit. The duration of follow-up ranged from nine to 38 months. The length of survival of nonresponders ranged from one month to 19 months (median, eight months; mean, seven months). Ten of the 19 responders relapsed, and the others were still responding. Three patients (7%) survived two years, disease-free. Although the response rate improved, the chance of long-term survival was still unsatisfactory in our study.

Abscess of urachal remnant mimicking urinary bladder neoplasm

Three cases of urachal abscess with extensive interstitial inflammation and fibrosis are reported. Clinically, all patients had a lower abdominal mass and CT scan and ultrasonic examination revealed a large tumour located anterior or superior to the bladder. They all underwent laparotomy and had either a partial cystectomy or an en bloc resection of the bladder and adjacent organs due to severe adhesions. Microscopic examination of the specimens revealed no evidence of carcinoma and only abscess formation with extensive chronic interstitial inflammation and fibrosis were seen. In one case, residual columnar epithelium suggestive of urachal origin was identified in the abscess cavity. Urachal abscess should be considered when dealing with lower abdominal masses.

Platelet alpha-2 adrenoreceptor activity pre-treatment and post-treatment in major depressive disorder with melancholia

Changes in alpha-2 adrenoreceptor density and affinity during antidepressant treatment were studied using 3H-yohimbine binding to human platelet membranes. Baseline measurements were conducted in 21 patients diagnosed as having major depressive disorder with melancholia, and an equal number of age and sex matched normal controls. No differences were observed in receptor density or binding between pre-treatment subject groups and normal matched controls. Subjects participated for 6 weeks in a trial of placebo, adinazolam, or amitriptyline. Alpha-2 adrenoreceptor binding was not significantly changed from baseline following antidepressant treatment.

Low oxygenation index and pulmonary artery hypertension in predicting early death from adult respiratory distress syndrome (ARDS)

Hemodynamic and respiratory parameters were continuously monitored in 45 septic shock patients, 15 of whom developed adult respiratory distress syndrome (ARDS). Low oxygenation index (OI = PaO2/FIO2), pulmonary artery hypertension (high mean pulmonary artery pressure, MPAP) and elevated pulmonary vascular resistance (PVR) were observed in all ARDS, as well as in non-ARDS septic patients, as a baseline. These same pulmonary factors were compared between those who survived and those who died during the first few days (early fatalities) in both the ARDS group (5 patients) and the non-ARDS group (8 patients). The results showed that the early fatalities in the ARDS group had a significantly lower (p less than 0.001) OI than the survivors, as well as a lower MPAP (p less than 0.01). In the non-ARDS group, the MPAP of the early fatalities was significantly lower (p less than 0.01) than that of survivors, but their OI was not significantly lower. PVR, when compared between groups (ARDS versus non-ARDS) or between subgroups within each group, was elevated concurrently with the elevation of MPAP. It is concluded that patients with septic shock and ARDS who show a severely depressed OI and a modestly elevated MPAP and PVR during the first few days can be predicted to have a poor outcome.

The relation of rural alcoholism to farm economy

Several studies have suggested an association between the farm crisis of the 1980's and the increase in mental health problems in rural America. A stress hypothesis for alcoholism would indeed predict such an association. The study presented herein examines the rate of new referrals for treatment of alcohol abuse and/or dependence to state-funded agencies in Nebraska. Between mid-1978 and mid-1986, the rate of subjects seeking treatment grew steadily, paralleling an increase in both population and available treatment programs. Yet, the total number of farmers seeking treatment peaked around 1982 and declined steadily thereafter, outpacing any change in the total number of farmers in the state. Possible interpretations of these findings are discussed.

Seasons of birth and subtypes of schizophrenia

Many studies show a higher rate of birth of schizophrenic patients during the winter and early spring months. This is particularly prominent in studies involving northern European countries and the northern part of the United States. The interpretations for this apparent seasonality remain highly speculative. We examined the seasons of birth of 472 patients carrying the diagnosis of schizophrenia. We also studied the gender and paranoid vs nonparanoid subtypes of this subject group. The total group does not show an excess of winter births. The same is true for total male (n = 193) and total female (n = 279) schizophrenic patients. The different subtypes of female patients show a homogenous distribution by seasons of birth; but the male paranoid schizophrenia group (n = 102) shows a significant increase of births during the first quarter of the year. The findings are interpreted according to the prevailing hypotheses of schizophrenia. The implications of these findings are discussed.

Psychotropic medication and nonfatal cafe coronary

Obstructive asphyxia, also known as cafe coronary, has been linked to both medicated and nonmedicated psychiatric patients. An 18-month prospective audit of choking patients was conducted in a psychiatric hospital. Based upon all medications received in the 5 days preceding the event, mean daily chlorpromazine and atropine equivalent dosages were also calculated for age, sex, and diagnosis matched controls based upon all medications received during their entire hospital stay. Paired t-tests showed no significant differences between choking patients and their matched controls except that greater mean daily chlorpromazine equivalents were present in the severe choking subgroup. Computation of log odds of choking risk increases with interaction of increased mean doses of each drug type and age, and also with interaction of increased chlorpromazine equivalents and increased atropine equivalents. Patients receiving high dosages of drug(s) with antidopaminergic or anticholinergic activity are at greater risk of choking and should be monitored closely.

Conformity in condylar replacement knee prosthesis

Experiments were carried out to determine the optimum conformity between the femoral and tibial condyles in condylar replacement knee prostheses. Wear tests and observations from removed prostheses indicated that both high and low conformity produced characteristic abrasion and fatigue. Partly conforming condyles provided stability under load-bearing but allowed laxity to occur. Fixation to resist the various forces on the tibial components was enhanced by a short central intramedullary peg. Partial conformity is proposed as the optimum configuration between femoral and tibial components.

Stabilizing mechanisms of the loaded and unloaded knee joint

Knee specimens were placed in an apparatus which imposed cyclic anterior-posterior or rotatory forces, with various compressive loads applied to the joint. Force-displacement graphs or torque-rotation graphs were automatically plotted, giving the laxity under various conditions. The ligaments, capsule, and menisci provided joint stability under no-load conditions. However, under compressive loads, the conformity of the condylar surfaces was an important factor in stabilizing the knee. The mechanism proposed was the uphill movement of the femur as the femur and the tibia were displaced or twisted relative to one another.