Controlling the optical and magnetic properties of CdTeSe and Gd-doped CdTeSe alloy semiconductor nanocrystals.

In this study, CdTexSe1-x (0 ≤ x ≤ 1) and CdTeSe:Gd y% (y = 0-8.05) alloy semiconductor nanocrystals (NCs) were prepared by wet chemical method. The presence and composition of the elements in the sample were determined by energy dispersive X-ray (EDX) spectroscopy and X-ray photoelectron spectroscopy (XPS). Structural analysis of X-ray diffraction (XRD) patterns indicated that most NCs crystallized in the zinc blende (ZB) structure however some Gd-doped NCs (y = 4.52 and 8.05%) crystallized in the wurtzite (WZ) structure. The emission peak of CdTexSe1-x (0 ≤ x ≤ 1) NCs varied over a wide range when changing x while the particle size remained almost unchanged. The effect of Gd doping on the structure and optical and magnetic properties of CdTeSe NCs was studied in detail. When the Gd concentration increases from 0-8.05%: (i) the structure of CdTeSe NCs gradually changed from ZB to WZ, (ii) the emission efficiency of the material was significantly reduced, (iii) the PL lifetime of samples increased more than 10 times, and (iv) the ferromagnetic properties of the material were enhanced. The research findings demonstrated that it is possible to control the crystal structure, optical characteristics, and magnetic properties of Gd-doped CdTeSe nanocrystals by adjusting the dopant concentration and chemical composition of the host material.

New insights on the luminescence properties and Judd-Ofelt analysis of Er-doped ZnO semiconductor quantum dots.

In this study, Er3+ doped ZnO semiconductor quantum dots (QDs) were synthesized using a wet chemical method. The successful doping of Er3+ ions into the ZnO host lattice and the elemental composition was confirmed by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The ZnO and Er3+ doped ZnO QDs with a hexagonal structure, spherical shape, and particle size of approximately 5 nm were revealed by XRD and transmission electron microscopy (TEM). The absorption, luminescence properties, and fluorescence lifetimes of the samples were studied as the concentration of Er3+ ions varied. The intensity parameters, emission transition probabilities, branching ratios, and emission lifetimes of the excited levels of Er3+ ions in the ZnO host were determined using the Judd-Ofelt theory, which provided insight into the covalent relationship between the ions and ligands as well as the nature of the ZnO host lattice. Moreover, the energy transfer process from the ZnO host to Er3+ ions and the yield of this process are explained in detail along with specific calculations. The Er3+ doped ZnO QDs displayed a significantly longer lifetime than undoped ZnO, which opens up many potential applications in fields such as photocatalysis, optoelectronics, photovoltaics, and biosensing.

New insights on the energy transfer mechanisms of Eu-doped CdS quantum dots.

Eu-doped CdS quantum dots (QDs) with the Eu dopant concentration in the range of 0.5-10% and zinc blende (ZB) structure were successfully synthesized by a wet chemical method. The fabricated Eu-doped CdS QDs exhibited emissions in the visible window approximately at 465, 590, 618 and 696 nm, which correspond to the excitonic emission of CdS QDs and the electronic transitions of the intra 4f6 configuration from the 5D0 level to 7F1, 7F2 and 7F4 levels of Eu3+ dopant ions, respectively. Judd-Ofelt theory was used to estimate the properties of ligand field and luminescence quantum efficiency of the material. The interaction mechanism and the efficiency of the energy transfer process from CdS QDs to Eu3+ ions were found by using Reisfeld's approximation formulas. The luminescence quenching of Eu3+-doped CdS QDs was studied through analysis of emission spectra and decay curves. The dominant interaction mechanism between Eu3+ ions and energy transfer parameters have been found by fitting the decay curves to the Inokuti-Hirayama model. The cross-relaxation channels leading to the luminescence quenching of Eu3+ have also been predicted.

Neck and whole-body scanning with 5-mCi dose of (123)I as diagnostic tracer in patients with well-differentiated thyroid cancer.

OBJECTIVE: To determine whether a 5-mCi dose of 123I can be used as an effective radiotracer for assessing the presence of remnant thyroid tissue and for searching for metastatic lesions in patients with well-differentiated thyroid cancer as well as to attempt to ascertain whether a scan performed only at 4 hours is sufficient for accurate diagnosis and might replace the conventional protocol of scanning at both 4 hours and 24 hours. METHODS: We prospectively studied 27 patients who had undergone near-total thyroidectomy and had a documented diagnosis of well-differentiated thyroid carcinoma. Patients underwent scanning after receiving a 5-mCi dose of 123I, at a time when they had discontinued thyroid replacement therapy and had a thyrotropin level in excess of 30 mIU/mL. Whole-body images at 4 hours and 24 hours were obtained and were compared with posttherapy scans obtained 5 to 7 days after administration of 131I. Scans were interpreted by two board-certified nuclear medicine physicians. RESULTS: Of the 27 patients, 2 (7.4%) showed discordance between the 123I scan performed at 24 hours and the posttherapy 131I scan. When 4-hour images after administration of 123I were compared with the posttherapy 131I scans, a discordance rate of 14.8% (4 of 27 patients) was noted. In addition, two of these four patients showed lesions on the 24-hour images that were not seen on the 4-hour images (one with new lung metastatic involvement and the other with a local recurrence in the lower neck area). The prognosis and treatment of these two patients were substantially changed by the result of the 24-hour images. CONCLUSION: On comparison of scans obtained after administration of a 5-mCi dose of 123I with those obtained after 131I therapy, we conclude that 5 mCi of 123I produces images that have excellent quality and resolution and also compare favorably with those obtained after 131I therapy. Furthermore, a decrease in the dose of 123I from 10 mCi to 5 mCi lowered the cost of the study without compromising the diagnostic accuracy or image quality. Finally, use of 24-hour images will occasionally disclose additional areas of radioiodine uptake not detected on the 4-hour scans and is therefore recommended.

Evaluation of rapid diagnostic tests for the detection of human immunodeficiency virus types 1 and 2, hepatitis B surface antigen, and syphilis in Ho Chi Minh City, Vietnam.

An evaluation of three new rapid diagnostic test kits for human immunodeficiency virus types 1 and 2 (HIV-1/2), hepatitis B surface antigen (HBsAg), and syphilis involved a two-phase comparison of rapid diagnostic assays using prospectively collected from hospitals and clinics in Ho Chi Minh City, Vietnam. After specificity and sensitivity testing, three new rapid diagnostic test kits were tested in parallel with six commonly used diagnostic test kits. The Determine HIV-1/2 test had fewer indeterminate or equivocal results than the Capillus HIV-1/HIV-2 or HIV Blot 2.2 tests. However, the Determine HIV-1/2 test yielded one false-positive result when compared with the Serodia HIV, HIV Blot 2.2, and microparticle enzyme immunoassay (IMx) HIV tests. The Serodia HBsAg test yielded more false-negative results when compared with the Determine HBsAg diagnostic test kit. The results of the syphilis diagnostic tests evaluated in this clinical trial consistently agreed with those of the rapid plasma reagin test for syphilis. The Determine Syphilis Treponema pallidum (TP) test had three false-positive results compared with the Serodia TP and the Serodia TP x particle agglutination (PA) tests, which had two false-positive results that were confirmed as negative by an ELISA. Application of these serologic tests within this comparative evaluation framework, using the World Health Organization alternative testing strategies, proved to be an effective way to determine serostatus related to HIV, hepatitis B, and syphilis.

Pituitary gland metastases.

BACKGROUND: Symptomatic pituitary metastasis is an uncommon clinical problem. It may be difficult to distinguish pituitary metastasis from pituitary adenomas both clinically and radiographically. We present our experience with these tumors and compare it with the findings in the literature. METHODS: Eight cases are reported here. The medical records were reviewed concerning clinical features, radiographic findings, treatment, and outcome. RESULTS: Diabetes insipidus is associated with each case and was the initial manifestation of systemic malignancy in two of our patients. Half of the patients had headaches as well. Panhypopituitarism and visual field defects were noted in 25% of the patients. In 50% of the patients metastasis was limited to the pituitary gland only. All patients received radiation treatment and exogenous vasopressin. Two patients underwent resection of the tumor. Five patients died within a few months of diagnosis of pituitary metastasis. One patient died 2 years after the diagnosis and two patients were lost to follow-up. CONCLUSIONS: When a patient with known metastatic cancer develops diabetes insipidus and has radiographic evidence of a pituitary mass, the diagnosis of metastasis is highly probable. Reasonable treatment is palliative with exogenous vasopressin and radiotherapy.

Mitogenic and receptor activities of human growth hormone 108-129.

We have selectively synthesized a number of peptides encompassing the region of helix 3 of growth hormone (GH). These peptides and native human (h) GH have been evaluated for mitogenic and receptor activities in 3T3-F442A preadipocytes. In this system, wild type hGH is anti-mitogenic. In contrast, hGH 108-129 stimulated DNA synthesis while other GH-derived peptides were ineffective. hGH (L) 108-129 had an EC50 of about 0.2 nM and was maximally effective at about 0.5 nM in stimulating [3H]thymidine incorporation in 3T3-F442A cells. hGH (L) 108-129 was mitogenically as active as insulin-like growth factor-I and more active than insulin. It was less effective than transforming growth factor-beta. By cell cycle analysis, hGH (L) 108-129 increased the proportion of cells in S/G2/M phases to 28%. hGH, when coincubated with hGH (L) 108-129, blocked the mitogenic response of the peptide. A monoclonal antibody to the GH receptor significantly reduced binding of 125I-hGH to its receptor but had no effect on binding of 125I-hGH (L) 108-129. Affinity cross-linking of 125I-hGH to its receptor was not duplicated with 125I-hGH (L) 108-129. No other GH peptides or insulin competed for binding of 125I-hGH 108-129. Scatchard analysis indicated a Kd of 5.2 nM with 5.6 x 10(5) binding sites/cell for hGH (L) 108-129. These studies indicate that hGH (L) 108-129, a sequence encompassing helix 3 of hGH, acts by binding to a site other than the GH receptor and evokes high mitogenic responses.

Nueva técnica para determinar la catalasa. Aplicado a las bacteriurias / Primary orthostatic hypotension (Shy-Drager syndrome). Clinico-pathologic study of a case

La descomposición del agua oxigenada por los microorganismos, se realiza a expensas de la catalasa que ésta contiene. Desde 1983, Gottatein sugirió el uso de la reacción de esta enzima para detectar bacterias. En este artículo, se muestran los resultados obtenidos al realizar un estudio comparativo de 119 análisis de orina y 507 urocultivos, y en los que se utiliza la catalasa. La técnica empleada consiste en mezclar dos milimetros de orina con un milimetro de agua oxigenada (11 volúmenes) en una jeringuilla de cristal que tenga la aguja obturada con parafina, y se sitúa el émbolo en un punto de partida y se agita; el resultado se mide a la hora en milimetros de oxigenos, que marca el desplazamiento de émbolo. A cada muestra de orina se le hacen tres determinaciones: a las 4, 24 y 48 horas. La orina se deja a temperatura ambiente. El 87,6 porciento de las orinas con bacterias, por el urocultivo, fueron positivas al medir la catalasa (AU)

Determinación de las proteínas de Bence Jones por la técnica de Ouchterlony en 447 pacientes ingresados en el IOR (II) / Determination of Bence Jones proteins by Ouchterlony technique in 447 patients hospitalized at the IOR

Se determinan las proteínas de Bence Jones y la Gamma G, por la técnica de Ouchterlony, en la orina de 447 pacientes ingresados en el OIR. Se relacionan los pacientes que presentan PBJ con la edad, afección renal, eritrosedimentación, hemoglobina y localización de la enfermedad. Los resultados obtenidos y los estudios de otros investigadores nos inducen a tomar el criterio de que la presencia de las PBJ en la orina se relacionan con procesos degenerativos o destructivos, que acompañan a las neoplasias malignas (activas) o a su tratamiento, y que la presencia de las PBJ en la orina, nos debe orientar en el sentido de establecer si el paciente se encuentra afectado por algún síntoma clínico como: nefropatías, hipercolesteronemia, coagulación anormal, anemia, leucopenia, hipercalcemia, amiloide, inmunodeficiencias, etc., planteadas por Osterland, y considerar la presencia de las PBJ como causa de las afecciones señaladas. Se debe evaluar posteriormente, si el tratamiento contra la neoplasia maligna elimina la presencia de las PBJ en la orina y, a la vez, los procesos secundarios, de lo cual, creemos, que constituyen la causa (AU)

Determinacion de las proteinas de Bence Jones por la tecnica de Ouchterlony en 447 pacientes ingresados en el IOR (II). / Deterination of Bence Jones' proteins by Ouchterlony technique in 447 patients hospitalized at the Instituto de Oncologia y Radiobiologia (II)

De determinan las proteinas de Bence Jones y la Gamma G, por la tecnica de Ouchterlony, en la orina de 477 pacientes ingresados en el IOR. Se relacionan los pacientes que presentan PBJ con la edad, efeccion renal, eritrosedimentacion, hemoglobina y localizacion de la enfermedad.Los resultados obtenidos y los estudios de otros investigadores2-5 nos inducen a tomar el criterio de que la presencia de las PBJ en la orina se relaciona con procesos degenerativos o destructivos, que acompanan a las neoplasias malignas (activas) o a su tratamiento, y que la presencia de las PBJ en la orina, nos debe orientar en el sentido de establecer si el paciente se encuentra afectado por algun sintoma clinico como: nefropatias, hipercolesterolemia, coagulation anormal, anemia, leucopenia, hipercalcemia, amiloide, inmunodeficiencias, etc., planteadas por Osterland, y considerar la presencia de las PBJ como causa de las afecciones senaladas. Se debe evaluar posteriormente, si el tratamiento contra la neoplasia maligna elimina la presencia do las PBJ en la orina y, a la vez, los procesos secundarios, de lo cual, creenos, que constituyen la causa

Determinacion de las proteinas de Bence Jones por la tecnica de Ouchterlony en 447 pacientes ingresados en el IOR (II). / Determination of Bence Jones' proteins by Ouchterlony technique in 447 patients hospitalized at the Instituto de Oncologia y Radiobiologia (II)

De determinan las proteinas de Bence Jones y la Gamma G, por la tecnica de Ouchterlony, en la orina de 477 pacientes ingresados en el IOR. Se relacionan los pacientes que presentan PBJ con la edad, efeccion renal, eritrosedimentacion, hemoglobina y localizacion de la enfermedad.Los resultados obtenidos y los estudios de otros investigadores2-5 nos inducen a tomar el criterio de que la presencia de las PBJ en la orina se relaciona con procesos degenerativos o destructivos, que acompanan a las neoplasias malignas (activas) o a su tratamiento, y que la presencia de las PBJ en la orina, nos debe orientar en el sentido de establecer si el paciente se encuentra afectado por algun sintoma clinico como: nefropatias, hipercolesterolemia, coagulation anormal, anemia, leucopenia, hipercalcemia, amiloide, inmunodeficiencias, etc., planteadas por Osterland, y considerar la presencia de las PBJ como causa de las afecciones senaladas. Se debe evaluar posteriormente, si el tratamiento contra la neoplasia maligna elimina la presencia do las PBJ en la orina y, a la vez, los procesos secundarios, de lo cual, creenos, que constituyen la causa

Effects of the variation of angle of incidence and temperature on infrared filter characteristics.

The effects of the variation of angle of incidence and temperature on the characteristics of some typical ir filters are discussed. Collimated radiation, Lambertian radiation, and focused radiation, from a point source at infinity are considered and theoretical calculations of the wavelength shifts and bandwidth changes of three narrow bandpass filter designs are presented. Measurements were made of other filters irradiated by collimated radiation at various angles of incidence and good correlation exists between theoretical and measured data. Measured variation of the characteristics of some filters with temperature are also presented. Results indicate that the filters shift toward shorter wavelengths if either the angle of incidence is increased or temperature is decreased.