Fabrication method of high-quality Ge nanocrystals on patterned Si substrates by local melting point control.

The local melting point of a Ge thin film can be controlled by a hole-array pattern on the host Si substrate due to the variations in the stress distribution and the surface morphology induced by the pattern. A simple annealing process is developed from this effect to produce Ge NCs with a single-domain-crystal size over 20 nm, confirmed by transmission electron microscopy and Raman spectroscopy, from an electron-gun-evaporated Ge thin film on the patterned Si substrate. The effect of the dimensions of the hole array is also investigated. Photoluminescence observed around 1157 nm from some of the samples shows the possibility of improving the infrared emission capability by this proposed method.

Fabrication of high-aspect-ratio Fresnel zone plates by e-beam lithography and electroplating.

The fabrication of gold Fresnel zone plates, by a combination of e-beam lithography and electrodeposition, with a 30 nm outermost zone width and a 450 nm-thick structure is described. The e-beam lithography process was implemented with a careful evaluation of applied dosage, tests of different bake-out temperatures and durations for the photoresist, and the use of a developer without methylisobutylketone. Electrodeposition with a pulsed current mode and with a specially designed apparatus produced the desired high-aspect-ratio nanostructures. The fabricated zone plates were examined by electron microscopy and their performances were assessed using a transmission X-ray microscope. The results specifically demonstrated an image resolution of 40 nm.

Seasonal variation in suicides: diminished or vanished. Experience from England and Wales, 1982-1996.

BACKGROUND: Seasonal variation in suicidal death has been observed in many countries. In particular, a cyclic variation was found for both men and women in England and Wales in the 1960s and 1970s. Men showed a single 12-month cycle whereas women showed two cycles. AIMS: To re-examine the seasonal variation in suicides in England and Wales for the period 1982-1996. METHOD: A harmonic analysis was used to detect the seasonality of the suicide data. RESULTS: The seasonal effect on suicide is greatly diminished in England and Wales. This is shown by the reduced amplitude and smaller proportion of variance accounted for by the season. CONCLUSIONS: The seasonal effect on suicide has either diminished or vanished.

Measuring change across multiple occasions using the Rasch Rating Scale Model.

When latent trait models are used to measure change across time, it is difficult to disentangle changes in one facet of the measurement context from changes in other facets. Hence, it is difficult to diagnose change. Wright (1999b) proposed an algorithm for disentangling change, and previously the authors applied this algorithm to measuring change across two occasions (Wolfe and Chiu, 1999). In this article we extend Wright's algorithm to disentangle changes in measures across three occasions. We describe a standard Rasch rating scale analysis of a multi-occasion evaluation that produces confusing results when subjected to a series of "separate" calibrations. Then, we apply Wright's correction to the same data to show that the algorithm reveals changes that are more similar to ones that would be expected. Our demonstration shows that Wright's procedure can reduce misfit to the Rasch Rating Scale Model as well as changing the interpretation of change within the measurement context.

The influence of recovery status and education on addiction counselors' approach to treatment.

The goal of this study is to examine the influence of education and recovery status on substance abuse treatment counselors' approach to patients. Three hundred forty-four drug abuse and alcoholism treatment counselors were questioned about treatment goals. A subgroup of 197 were also questioned about treatment practices. The influences of education and recovery status on the choice of treatment goals and treatment practices were examined through structural modeling procedures. Level of education influenced neither treatment goals nor techniques. Being in recovery, however, was associated with more varied treatment techniques and a broader range of treatment goals. The other variable related to treatment goals and practices was treatment modality. Working in residential programs was linked to a wider range of treatment goals and treatment practices. Implications of these findings for counselor training and the movement to professionalize substance abuse treatment are discussed.

Measuring pretest-posttest change with a Rasch Rating Scale Model.

When measures are taken on the same individual over time, it is difficult to determine whether observed differences are the result of changes in the person or changes in other facets of the measurement situation (e.g., interpretation of items or use of rating scale). This paper describes a method for disentangling changes in persons from changes in the interpretation of Likert-type questionnaire items and the use of rating scales (Wright, 1996a). The procedure relies on anchoring strategies to create a common frame of reference for interpreting measures that are taken at different times and provides a detailed illustration of how to implement these procedures using FACETS.

Suicide notes: what do they tell us?

Police investigation records of all suicide cases in 1992 (n = 769) and the suicide notes that had been left (224 notes for 154 subjects) were examined. Note-leavers were characterized as young females, of non-widowed marital status, with no history of previous suicide attempts, no previous psychiatric illness, and with religious beliefs. Suicide notes written by young people were longer, rich in emotions, and often begging for forgiveness. Suicide notes written by the elderly were shorter, contained specific instructions, and were less emotional. A significant proportion of note-leavers did mention their difficulties. Suicide notes may serve some explanatory purpose and may have a therapeutic role in helping the surviving relatives to understand the suicide. A knowledge of the messages contained within suicide notes could be useful for suicide prevention programmes. The significance of suicide notes is best understood within the context of the occurrence of suicides.

Rare combination of spinal lesions and spina bifida occulta: case report.

An infant presented with spina bifida occulta and a rare combination of spinal lesions, consisting of fibrous band with skin tag, lipoma, congenital dermal sinus and arachnoid cyst. The literature concerning the arachnoid cyst in occult spinal dysraphism is reviewed and the embryogenesis of these lesions is discussed.

Spontaneous regression of a cerebral arteriovenous malformation. Report of a case and review of the literature.

A cerebral arteriovenous malformation (AVM) spontaneously and completely disappeared on subsequent angiography. Computed tomography revealed a very similar picture to that of angiographically occult AVM, which was histologically thrombotic. Reviewing the literature, we suggest that in many cases the important factor related to regression of AVM is a previous bleeding episode.

Mutagenicity of some commercially available nitro compounds for Salmonella typhimurium.

Benzoyl chloride and 53 commercially available aromatic heterocyclic and aliphatic nitro compounds were tested for mutagenicity in Salmonella typhimurium TA98 and TA100. 34 of 53 nitro compounds (64%) were mutagenic, 4 in TA100 only, 15 in TA98 only, and 15 in both strains. 13 of the heterocyclic derivatives of pyridine, indole, indazole, quinoline, and benzimidazole were mutagenic. 21 of 34 mutagenic nitro compounds were bactericidal. Nitromethane was the only aliphatic tested and was not mutagenic. Benzoyl chloride, a human carcinogen, was mutagenic for TA98.

Identification of carcinogenic tannin isolated from Bracken fern (Pteridium aquilinum).

We attempted to isolate a carcinogenic substance from bracken fern (Pteridium aquilinum), a naturally occurring toxicant responsible for the production of chronic enzootic hematuria and urinary bladder cancer of cattle and carcinogenic for various target organs of several species. Hot methanol extracts of bracken fern were solubilized in water and extracted with chloroform followed by a mixture of n-butanol-butanone (1:1). That fraction was dried and triturated with ether-methanol (4:1), n-butanol, and finally absolute ethanol. The insoluble residue was dissolved in 10% aqueous methanol and passed through Dowex 1 OH-, Dowex 50 H+, or Dowex 1 OH- and then Dowex 50 H+ ion exchange resins. A condensed tannin, isolated from one ot the fractions, was identical to that isolated from bracken fern by the caffeine procedure used for the separation of tannins from other plant constituents. Three systems were used for bioassay; induction of bladder carcinoma by implantation of cholesterol pellets containing bracken fern fractions into the bladder lumens of mice; acute toxicity by ip injection of brachen fern fraction into mice; and growth inhibition of Escherichia coli. The following fractions induced significantly greater incidences of bladder carcinoma than did cholesterol pellets only: tannin, Dowex 50 H+, residue, n-butanol, and methanol. Tiliroside, a component of bracken fern fractions into the bladder lumens of mice; acute genic acid, and quercetin were not carcinogenic. Tannin was the most toxic (mean lethal dose: 0.16 mg/g) and carcinogenic. None of the carcinogenic fractions inhibited growth of E. coli.

Antibacterial activity of nitropyrroles, nitrothiphenes, and aminothiophenes in vitro.

The antibacterial activities of nitropyrroles, nitrothiophenes, and aminothiophenes were studied. Replacement of the nitro group with an amino group enhanced the activity of the thiophene compounds.

Metabolism and disposition of N-(4-(5-nitro-2-furyl)-(2-14-C)thiazolyl)acetamide in the rat.

The metabolism of N-[4-(5-nitro-2-furyl)-2-thiazolyl]acetamide (NFTA), a carcinogen for the mouse, rat, dog, and hamster, was investigated in the rat. Radioactive NFTA administered ip to young and lactating female rats was rapidly absorbed through the peritoneum and deposited in the urine, intestinal contents, and feces. Less than 0.5% of the radioactivity was expired as CO2 during the first 24 hr. Two yellow metabolites, accounting for 5 and 27% of the radioactivity in the urine, were found by paper chromatography. One metabolite retained the 2-amino-4-(5-nitro-2-furyl)thiazole moiety. Less than 0.5% of the radioactivity in the urine was due to unchanged 14-C-NFTA. The radioactivity level in the visceral organs reached a maximum 2 hr after dosing and then gradually decreased. Liver contained considerably more radioactivity than did other visceral organs; this was mainly distributed in the cytosol and 900g pellets. Fifty per cent of the radioactivity in the liver was bound to the hot trichloroacetic acid (TCA)-insoluble fraction; that bound to the cold TCA-insoluble fraction increased gradually from 66.9% at 2 hr to 82.6% at 24 hr. The radioactivity bound to the cold and hot TCA-insoluble fractions in kidney remained at 30% and 20%, respectively. Nitroreduction of 14-C-NFTA by microsomes, as a prerequisite of the binding of metabolite to microsomal protein, was demonstrated. Addition of L-cysteine or reduced glutathione to the incubation mixture did not alter the nitroreductase activity of the microsomes; however, binding of radioactivity to protein was significantly decreased. Addition of other amino acids did not significantly decrease the nitroreductase activity or binding to protein. These results suggest that reduced NFTA binds to the protein sulfhydryl groups. Since 14-C-NFTA binds to macromolecules in vivo,nitroreductionmay be important for the metabolism of 5-nitrofurans.