Surface analysis of metal clips of ceramic self-ligating brackets / 대한치과교정학회지

OBJECTIVE: The aim of this study was to analyze the surface composition, roughness, and relative friction of metal clips from various ceramic self-ligating brackets. METHODS: Six kinds of brackets were examined. The control group (mC) consisted of interactive metal self-ligating brackets while the experimental group (CC, EC, MA, QK, and WA) consisted of interactive ceramic self-ligating brackets. Atomic force microscopy-lateral force microscopy and scanning electron microscopy-energy-dispersive X-ray spectroscopy were used to analyze the surface of each bracket clip. RESULTS: All the clips in the experimental groups were coated with rhodium except for the QK clip. The results showed that the QK clip had the lowest average roughness on the outer surface, followed by the MA, EC, WA, and CC clips. However, the CC clip had the lowest average roughness on the inner surface, followed by the QK, WA, MA, and EC clips. The QK clip also had the lowest relative friction on the outer surface, followed by the MA, EC, CC, and WA clips. Likewise, the CC clip had the lowest relative friction on the inner surface, followed by the QK, WA, MA, and EC clips. CONCLUSIONS: The surface roughness and relative friction of the rhodium-coated clips were generally higher than those of the uncoated clips.

Road dust and its effect on human health: a literature review / 한국역학회지

The purpose of this study was to determine the effects of road dust on human health. A PubMed search was used to extract references that included the words “road dust” and “health” or “fugitive dust” and “health” in the title or abstract. A total of 46 references were extracted and selected for review after the primary screening of 949 articles. The respiratory system was found to be the most affected system in the human body. Lead, platinum-group elements (platinum, rhodium, and bohrium), aluminum, zinc, vanadium, and polycyclic aromatic hydrocarbons were the components of road dust that were most frequently referenced in the articles reviewed. Road dust was found to have harmful effects on the human body, especially on the respiratory system. To determine the complex mechanism of action of various components of road dust on the human body and the results thereof, the authors recommend a further meta-analysis and extensive risk-assessment research into the health impacts of dust exposure.

Road dust and its effect on human health: a literature review / 한국역학회지

The purpose of this study was to determine the effects of road dust on human health. A PubMed search was used to extract references that included the words “road dust” and “health” or “fugitive dust” and “health” in the title or abstract. A total of 46 references were extracted and selected for review after the primary screening of 949 articles. The respiratory system was found to be the most affected system in the human body. Lead, platinum-group elements (platinum, rhodium, and bohrium), aluminum, zinc, vanadium, and polycyclic aromatic hydrocarbons were the components of road dust that were most frequently referenced in the articles reviewed. Road dust was found to have harmful effects on the human body, especially on the respiratory system. To determine the complex mechanism of action of various components of road dust on the human body and the results thereof, the authors recommend a further meta-analysis and extensive risk-assessment research into the health impacts of dust exposure.

Usefulness of a Small-Field Digital Mammographic Imaging System Using Parabolic Polycapillary Optics as a Diagnostic Imaging Tool: a Preliminary Study

OBJECTIVE: To evaluate the efficacy for spatial resolution and radiation dose of a small-field digital mammographic imaging system using parabolic polycapillary optics. MATERIALS AND METHODS: We developed a small-field digital mammographic imaging system composed of a CCD (charge coupled device) detector and an X-ray source coupled with parabolic polycapillary optics. The spatial resolution and radiation dose according to various filters were evaluated for a small-field digital mammographic imaging system. The images of a test standard phantom and breast cancer tissue sample were obtained. RESULTS: The small-field digital mammographic imaging system had spatial resolutions of 12 lp/mm with molybdenum and rhodium filters with a 25-micrometer thickness. With a thicker molybdenum filter (100 micrometer thick), the system had a higher spatial resolution of 11 lp/mm and contrast of 0.48. The radiation dose for a rhodium filter with a 25-micrometer thickness was 0.13 mGy within a 10-mm-diameter local field. A larger field image greater than 10 mm in diameter could be obtained by scanning an object. On the small-field mammographic imaging system, microcalcifications of breast cancer tissue were clearly observed. CONCLUSION: A small-field digital mammographic imaging system with parabolic polycapillary optics may be a useful diagnostic tool for providing high-resolution imaging with a low radiation dose for examination of local volumes of breast tissue.

Tomografia Computadorizada com raios-x monoenergético / Compuitadorized tomography with monoenergetic x-rays

Neste trabalho, apresenta-se a utilização de filtros no feixe de raios-X, para produção de radiação quase monoenergética e sua utilização em tomografia. Os filtros utilizados foram 100mum de Cu, 25 e 50 mum de Rh e de resina com 40mg/cm2 de Cd. Os resultados apresentados mostram uma comparação das imagens obtidas.

ln this work the utilisation of filters place in the beam of X-ray to production of quasi-monoenergetic radiation and its utilisation in tomography is described. The filters utilised were 1 OOµm of Cu, 25 and 50µm of Rh and filters prepared with resins, 40mg/cm2-Cd. The results show a comparison of the acquired images.

Dosimetric Evaluation of Average Glandular Absorption Radiation Dose in Mammography

PURPOSE: To evaluate the average glandular absorption radiation dose(AGARD) that results from tube voltage, target/filter material of the X-ray tube, enterance skin exposure, breast thickness and patterns in routine mammography. MATERIAL AND METHOD: After obtaining craniocaudal views of left breasts of 114 women, entrance skin exposure was measured by dosimetry. Under identical conditions of tube voltage and target/filter material of theX-ray tube, we obtained half value layer (HVL) and also calculated exposure-to-absorbed dose conversion factor(DgN) by Wu's methods. AGARD was calculated by entrance skin exposure multiplied by exposure-to-absorbed dose conversion factor. We analyzed AGARDs according to tube voltage, target/filter material, breast thickness and pattern using ANOVA method of the SPSS statistical packages. RESULT: Breast patterns were divided into 4 groups such as DY (n=72), P1 (n=1), P2 (n=10), and N1 (n=31), respectively. Their AGARDs were 161.5, 180, 172.8, and195.2 mrad respectively and showed no significant difference among groups. When divided by breast thickness into three groups, namely below 3cm, 3cm to 4.5cm, and above 4.5cm, the AGARD of each group was 178.3, 178.1, and 112.4mrad respectively and the last one was significantly low. Concerning the effect of tube voltages, AGARDs gradually decreased by increasing kVp. Furthermore, AGARD was lower when rhodium (Rh) rather than when molybdenum(Mo) was used as filter/target materials. CONCLUSION: There was no difference in AGARDs by breast pattern. Asmore increasing KvP or using Rh/Rh as the target/filter material of the X-ray tube, we reduced AGARD for the patient with dense or thick breasts.

Antitumor effects of rhodium (II) complexes on mice bearing Ehrlich tumors

Rhodium (II) trifluoracetate (TFARh), rhodium (II) trifluoracetate adduct with sulfadiazine (TFARh.Sd) and rhodium (II) acetate adduct with sulfisoxazole (RhSx) were tested in mice for acute toxicity, antitumoral activity against Ehrlich ascites carcinoma and for viability of Ehrlich tumor cells in culture. At ip doses up to 60 µmg/kg (40-70 and 59 mg/kg, respectively), these coumpounds had no toxic effects up to 14 days. At ip doses of 10 µmol Kg-1 day-1 for 5 days, TFARh and TFARh.Sd significantly increased the survival rate of mice bearing Ehrlich ascites cells (probability of survival to the end of 34th day, controls = 0.23, TFARh = 0.85, TFARh.Sd = 0.74). No significant effect was observed for RhSx. In vitro, these rhodium complexes at 40 µM significantly increased the number of dead cells in cultured Ehrlich tumor cells

Antitumor effects of Rhodium (II) citrate in mice bearing Chrlich tumors

Rhodium II citrate was tested in mice for acute toxicity, antitumoral activity against Ehrlich ascites carcinoma and inhibition of DNA synthesis by Ehrlich tumor, malignant adrenocortical cells (Y-1) and normal adrenocortical cells (AR-1)_. At ip doses up to 260 mg/Kg, the compound had no toxic effects for up to 14 days. The same total dose given over 4 days significantly increased the survial rat of mice bearing Ehrlich ascites cells. Thymidine incorporation by Ehrlkich tumor, Y-1 cells in vitro was inhibited 50% by a.1 to 0.2 mM concentrations of the compound. We conclude that the increase survival of the tumor-bearing mice was due at least in part to the inhibition of DNA synthesis with a consequet reduction of cell division and tumor growth

Citrato do ródio: II. Modelo de agente inflamatório / Rodium citrato: II. Inflamatory agent model

o citrato de ródio II sintetizado na procura de complexos de ródio com atividade anti-tumoral e baixa toxicidade. Näo foram observados mortes ou outros sinais de toxicidade após injeçäo de 260 mg/Kg de citrato de ródio II, intra-peritonial em camundongos observados durante 14 dias. A substância provaca um quadro inflamatório que se caracteriza por edema persistente por 24 horas, quando injetada na pata de ratos. Injetada na cavidade peritonial há aumento de neutrófilos segmentados no exudato peritoneal bem como aumento significativo no número de macrófagos espraiados