Photocrosslinking and photopatterning of magneto-optical nanocomposite sol-gel thin film under deep-UV irradiation.

This paper is aimed at investigating the process of photocrosslinking under Deep-UV irradiation of nanocomposite thin films doped with cobalt ferrite magnetic nanoparticles (MNPs). This material is composed of a hybrid sol-gel matrix in which MNP can be introduced with high concentrations up to 20 vol%. Deep-UV (193 nm) is not only interesting for high-resolution patterning but we also show an efficient photopolymerization pathway even in the presence of high concentration of MNPs. In this study, we demonstrate that the photocrosslinking is based on the free radical polymerization of the methacrylate functions of the hybrid precursor. This process is initiated by Titanium-oxo clusters. The impact of the nanoparticles on the photopolymerization kinetic and photopatterning is investigated. We finally show that the photosensitive nanocomposite is suitable to obtain micropatterns with sub-micron resolution, with a simple and versatile process, which opens many opportunities for fabrication of miniaturized magneto-optical devices for photonic applications.

Room-temperature ferromagnetism of all-epitaxial ß-Fe-Ge/diamond-Ge/ß-Fe-Ge trilayers.

We report on the first all-epitaxial ferromagnet/inorganic semiconductor/ferromagnet hybrid heterostructure that exhibits (i) a Ge barrier of diamond crystal structure, (ii) room-temperature ferromagnetic electrodes and (iii) very smooth interfaces. Both bottom- and top-Fe-Ge electrodes exhibit tiny in-plane magnetic anisotropies dominated by a magnetocrystalline contribution of six-fold symmetry originating from the hexagonal symmetry of the B82 (Ni2In) ß-Fe-Ge phase. A key result is the absence of any magnetic coupling between these soft-magnetic electrodes for Ge barrier thickness as low as ~2.5 nm, which allows us to easily tune the parallel and antiparallel magnetic alignments by applying suitably small magnetic fields. This confirms the beneficial use of H-surfactant in order to drastically reduce the roughness of the Ge barrier, as revealed by our scanning tunneling microscopy and transmission electron microscopy measurements. This new all-epitaxial ferromagnet/semiconductor hybrid system appears, therefore, to be a promising candidate for the realization of magnetic tunnel junctions with a single crystal semiconductor barrier that are fully compatible with Si-based technology.

Comparison of survival probabilities for dialysis patients vs cadaveric renal transplant recipients.

OBJECTIVE: To compare mortality risk among cadaveric renal transplant recipients vs transplant candidates on dialysis in the cyclosporine era. SETTING: Patient mortality risk was analyzed by treatment modality for a completed statewide patient population. PATIENTS: All Michigan residents younger than age 65 years who started endstage renal disease (ESRD) therapy between January 1, 1984, and December 31, 1989, were included. Patients were followed up from ESRD onset (n = 5020), to wait-listing for renal transplant (n = 1569), to receiving a cadaveric first transplant (n = 799), and to December 31, 1989. MAIN OUTCOME MEASURE: Mortality rates. RESULTS: Using a time-dependent variable based on the waiting time from date of wait-listing to transplantation and adjusting for age, sex, race, and primary cause of ESRD, the relative risk (RR) of dying was increased early after transplantation and then decreased to a beneficial long-term effect, given survival to 365 days after transplantation (RR, 0.36; P < .001). This lower long-term risk was most pronounced (RR, 0.25) among diabetic transplant recipients compared with diabetic wait-listed dialysis patients (P < .001) and not observed among patients with glomerulonephritis as cause of ESRD (P > .05). Overall, the estimated times from transplantation to equal mortality risk was 117 +/- 28 days and to equal cumulative mortality was 325 +/- 91 days. CONCLUSIONS: The overall mortality risk following renal transplantation was initially increased, but there was a long-term survival benefit compared with similar patients on dialysis. These analyses allow improved description of comparative mortality risks for dialysis and transplant patients and allow advising patients regarding comparative survival outcomes.

Comparative mortality risks of chronic dialysis and cadaveric transplantation in black end-stage renal disease patients.

In view of the relatively low mortality risk on dialysis and the high risk of allograft loss among black compared with white end-stage renal disease (ESRD) patients, we studied the relative mortality risks of all black renal transplant candidates in Michigan from 1984 to 1989. There were 770 black ESRD patients followed from wait-listing for cadaveric (CAD) kidney transplantation until the time of transplantation, death, or December 31, 1989. The time on dialysis prior to wait-listing exceeded 1 year in 24% of these patients. Black diabetic patients on the waiting list have more than twofold relative mortality risk (RR) compared with nondiabetic individuals (RR = 2.73, P < 0.001) while the RR by diabetes status among CAD transplant recipients was small. Overall, CAD transplantation was associated with elevated risk of mortality in the first month posttransplantation (RR = 3.39, P < 0.03). Cadaveric donor transplant and wait-listed dialysis patients have equal death rates 112 days after transplantation. Thereafter, death rates were lower for transplant recipients compared with transplant candidates on dialysis. One year after transplantation, CAD transplant recipients on the average have approximately half the risk of death compared with dialysis patients who remain on the waiting list (RR = 0.49, P < 0.03). The cumulative survival probabilities are superior in transplant recipients just beyond 1 year after transplantation. Therefore, CAD transplantation in black ESRD patients is associated with a high risk of mortality in the early period after transplantation. Beyond 1 year, black transplant recipients have a substantial survival advantage over corresponding dialysis patients on the waiting list.