Evaluación in vitro de la preparación de conductos mesiales de molares con instrumentos manuales Ni-Ti y Protaper Universal rotatorio / In vitro evaluation of mesial molars canals preparation with manual Ni-Ti instruments and rotatory Protaper Universal

Con la finalidad de disminuir los errores durante la preparación de los conductos radiculares, se han introducido diversas modificaciones en los sistemas de instrumentación mecanizados de níquel-titanio. Se realizó un estudio in vitro para comparar el grado de transporte que se presenta a nivel de la unión del tercio apical con el tercio medio de conductos radiculares con el sistema rotatorio Protaper Universal y el sistema manual de níquel-titanio, con la técnica de fuerzas balanceadas. Se trabajó con 52 conductos mesiales de 26 molares maxilares y mandibulares, las cuales fueron divididas en dos grupos. El primer grupo de conductos (n = 28)fueron instrumentados con Protaper Universal rotatorio y el segundo grupo de conductos (n = 24) fueron instrumentados con técnica manual de fuerzas balanceadas. Las raíces mesiales de los molares fueron sumergidas en una matriz de acrílico, la cual permitió manipular las preparaciones, realizar cortes transversales y comparar los conductos radiculares antes y después de la instrumentación, para establecer las diferencias quese apreciaron en cuanto al transporte apical. Las imágenes obtenidas fueron fotografiadas con un microscopio estereoscópico y analizadas mediante el programa Autodesk AutoCAD® 2007. Finalmente, los datos obtenidos fueron tabulados y analizados con el programa Stata® 9.0 v. En el presente trabajo Protaper provocó menos transporte apical comparado con la técnica manual de fuerzas balanceadas (AU)

In order to reduce errors during root canal preparation, there have been several changes in instrumentation with rotatory systems of nickel-titanium. This is an in vitro study and the aim was to compare the degree of transportation that occurs at the union between the apical third and half third of root canals with the rotaroty Protaper Universal and nickel titanium manual system with balanced force technique. We worked with 52mesial canals of 26 first and second maxillary and mandibular molars, which were divided into two groups. The first group (n = 28) was instrumented with rotary Protaper Universal and the second group (n = 24) was instrumented with manual technique with balanced force. The mesial roots of molars were immersed in a matrix of acrylic, which allowed manipulating the preparations with transversal cuts and comparing the wear of the root canals before and after the instrument to set the differences were observed in the apical transport. The images obtained were photographed with a stereoscopic microscope and analyzed with the Autodesk AutoCAD®2007. Finally, the data were tabulated and analyzed with Stata® V.9.0. Protaper Universal rotatory results showed a decreased apical transport compared with the manual technique with balanced forces (AU)

Fast determination of impurities in metallurgical grade silicon for photovoltaics by instrumental neutron activation analysis.

Standard wafer solar cells are made of near-semiconductor quality silicon. This high quality material makes up a significant part of the total costs of a solar module. Therefore, new concepts with less expensive so called solar grade silicon directly based on physiochemically upgraded metallurgical grade silicon are investigated. Metallurgical grade silicon contains large amounts of impurities, mainly transition metals like Fe, Cr, Mn, and Co, which degrade the minority carrier lifetime and thus the solar cell efficiency. A major reduction of the transition metal content occurs during the unidirectional crystallization due to the low segregation coefficient between the solid and liquid phase. A further reduction of the impurity level has to be done by gettering procedures applied to the silicon wafers. The efficiency of such cleaning procedures of metallurgical grade silicon is studied by instrumental neutron activation analysis (INAA). Small sized silicon wafers of approximately 200mg with and without gettering step were analyzed. To accelerate the detection of transition metals in a crystallized silicon ingot, experiments of scanning whole vertical silicon columns with a diameter of approximately 1cm by gamma spectroscopy were carried out. It was demonstrated that impurity profiles can be obtained in a comparably short time. Relatively constant transition metal ratios were found throughout an entire silicon ingot. This led to the conclusion that the determination of several metal profiles might be possible by the detection of only one "leading element". As the determination of Mn in silicon can be done quite fast compared to elements like Fe, Cr, and Co, it could be used as a rough marker for the overall metal concentration level. Thus, a fast way to determine impurities in photovoltaic silicon material is demonstrated.

Exercise-induced hyperthermia in childhood: a case report and pilot study.

UNLABELLED: Hyperthermia is characterized by an increase of body core temperature due to exogenous heat exposure and/or endogenous heat production. Contrary to fever the hypothalamic-controlled temperature set point remains unchanged. AIM: To demonstrate that exercise-induced hyperthermia is a common phenomenon in childhood. CASE: We describe a 5-year-old boy, who attended our outpatient clinic with a 6-month observation period of exercise-induced hyperthermia with rectal temperatures up to 39.0 degrees C. Characteristically temperature dropped to normal values after cessation of exercise. METHOD: In eight children aged 5-8, tympanic and rectal temperatures were measured before and after exercise. RESULTS: The rectal temperature increases frequently after exercise (p < 0.001), whereas tympanic temperature did not (p = 0.2). CONCLUSION: Benign hyperthermia should be considered in children with increased body temperature of unknown sources. The site of temperature measurement might be critical in the identification of this condition.

[Radiation exposure in the environment of patients after application of radiopharmaceuticals. Part 2: Therapeutic procedures]. / Strahlenexposition in der Umgebung von Patienten nach Radiopharmaka-Applikation. Teil 2: Nuklearmedizinische Therapien.

AIM: After therapeutical application of radionuclides the patient has to be regarded as a radioactive source. The radiation exposure differs from diagnostic nuclear medicine due to the amount of radioactivity and due to beta-radiation. Measurements of photon dose rates were carried out and estimates of beta-radiation outside the patient using Monte-Carlo methods. Calculations of maximum beta-ranges in tissue were also performed. Detailed knowledge of the radiation exposure close to the patient is of major importance with respect to radiation protection of the staff. METHOD: Photon dose rates for 32 patients were determined after treatment with [131I]NaI and [131I]meta-iodobenzylguanidin, [32P]Na2HPO4, [90Y]Zevalin and [153Sm]EDTMP. Readings were taken immediately after application at eight distances. RESULTS: For therapies with 131I photon dose rates amount to 2 mSv.h(-1).GBq(-1) close to the patient. Taking the typical activities of 3.7 GBq for thyroid carcinoma and up to 11 GBq for mIBG therapies into account this leads to a considerable radiation exposure of approximately 7.5 mSv/h and 20 mSv/h, respectively. At a distance of 2 m the dose rates fall to 1/100 compared to the vicinity. For 153Sm the maximum of 100 microSv.h(-1).GBq(-1) is significantly lower compared to therapies using radioiodine. After application of 32P or 90Y all photon dose rates are lower (<10 microSv.h(-1).GBq(-1)) but in both cases high energy beta-particles associated with high maximum ranges exceeding 1 cm in tissue have to be considered. CONCLUSION: The remarkable difference of the dose rates in the vicinity of the radioactive patient compared to readings at 2 m distance underlines the major importance of the distance for radiation protection. After application of nuclides emitting high energy beta-particles their contribution outside the patient should be considered. For typical procedures in the patient's vicinity the radiation exposure of the personnel remains below the annual limit of 20 mSv.

[Radiation exposure in the environment of patients after application of radiopharmaceuticals. Part 1: Diagnostic procedures]. / Strahlenexposition in der Umgebung von Patienten nach Radiopharmaka-Applikation. Teil 1: Nuklearmedizinische Diagnostik.

AIM: After application of radiopharmaceuticals the patient becomes a radioactive source which leads to radiation exposure in the proximity. The photon dose rates after administration of different radiopharmaceuticals used in diagnostic nuclear medicine were measured at several distances and different time intervals. These data are of importance for estimating the exposure of technologists and members of the public. PATIENTS, METHOD: In this study dose rates were measured for 67 patients after application of the following radiopharmaceuticals: 99mTc-HDP as well as 99mTc-pertechnetate, 18F-fluorodeoxyglucose, 111In-Octreotid and Zevalin and 123I-mIBG in addition to 123I-NaI. The dose rates were measured immediately following application at six different distances to the patient. After two hours the measurements were repeated and--whenever possible--after 24 hours and seven days. RESULTS: Immediately following application the highest dose rates were below 1 mSv/h: with a maximum at 780 microSv/h for 18F (370 MBq), 250 microSv/h for 99mTc (700 MBq), 150 microSv/h for 111In (185 MBq) and 132 microSv/h for 123I (370 MBq). At a distance of 0.5 m the values decrease significantly by an order of magnitude. Two hours after application the values are diminished to 1/3 (99mTc, 18F), to nearly (1/2) (123I) but remain in the same order of magnitude for the longer-lived 111In radiopharmaceuticals. CONCLUSION: For greater distances the doses remain below the limits outlined in the national legislation.

Microstructuring of solid-supported lipid layers using SAM pattern generation by scanning electrochemical microscopy and the chemical lens.

To prepare patterns of adsorption sites for alkanethiols with high lateral resolution, we used the scanning electrochemical microscopy (SECM) to etch masks into uniform layers of nickel coated on gold surfaces. The patterning of the nickel mask was accomplished in aqueous solutions by electrogenerating nitric acid out of nitrite at an ultramicroelectrode. Due to the sluggish kinetics of nickel etching in acidic media, the pattern generated by a 10-microm tip was about 50-microm wide, depending on the duration of the etching. As an alternative, applying the principle of the chemical lens by adding potassium hydroxide as a scavenger, the size of the adsorption sites had been reduced to 4 microm, independent of the duration of etching. In a follow-up step, monolayers of 11-mercaptoundecanoic acid were formed on the exposed gold areas of the surface by self-assembly. Fluorescent liposomes containing tetramethylrhodamine-labeled phospholipids were used to create solid-supported lipid layers (SSLLs). These fluorescent liposomes showed a selective binding affinity to the self-assembled monolayers (SAMs) modified areas, but not to the nickel surface. The patterns generated were imaged by the SECM itself, as well as by optical and fluorescence microscopy.

Reproducibility of post-exercise lactate and anaerobic threshold.

To test the effect of previous strenuous training on lactate (LA) formation and on changes of lactate threshold (AT) values, a group of seven male athletes aged 26.3 +/- 9.2 years, height 184 +/- 6.2 cm, body weight 79.3 +/- 8.1 kg, percentage of body fat 8.8 +/- 3.7 and VO2 max 56.2 +/- 5.4 ml/kg were examined on a treadmill to the maximum in the morning after 2 days of rest, and after 2 consecutive days of strenuous training. The subjectively perceived rate of fatigue (SPF) in the morning prior to the exercise test was assessed by means of a 5-grade score. The values of LA max, AT, and SPF on day 1 were 11.06 +/- 2.4 mmol/l, 3.5 +/- 0.4 m/s, and 0.6 +/- 0.4, respectively. The corresponding values on day 2 were 8.8 +/- 1.7 mmol/l, 4.0 +/- 0.3 m/s, and 2.0 +/- 0.5, respectively. The values on day 3 were 8.6 +/- 1.1 mmol/l, 4.1 +/- 0.4 m/s, and 2.1 +/- 0.7, respectively. Statistically significant differences on the 1st day were found in LA max, AT, and SPF compared with days 2 and 3. No significant differences were found between the values for the 2nd and 3rd days. AT values for day 1 were significantly lower than those for days 2 and 3. A significantly higher level of SPF in the morning prior to the test procedure was observed on days 2 and 3 compared with day 1. The AT and SPF values for days 2 and 3 showed no significant difference.(ABSTRACT TRUNCATED AT 250 WORDS)

[The hemostatic and fibrinolytic system in normal subjects and myocardial infarct patients. Effect of a standardized aerobic and anaerobic ergometric stress test]. / Hämostase- und Fibrinolysesystem bei Gesunden und Herzinfarktpatienten. Einfluss einer standardisierten aeroben und anaeroben ergometrischen Belastung.

After clinical examination, 14 asymptomatic post-infarction male patients and 12 healthy control persons, aged 35-62 years, underwent two bicycle-ergometry tests. After a 20-min aerobic test of moderate intensity both groups had slight activation of the clotting system simultaneously with favorably increased fibrinolytic activity. After stepwise submaximal aerobic exercise, postinfarction patients had marked activation of the thrombocytic system; beta-thromboglobulin rose significantly from 36 to 102 ng/ml. But compared to the results in healthy persons, fibrinolytic activity was significantly reduced in the postinfarction patients (euglobulin lysis time 135 and 100 min, respectively). In three patients with unfavorable reactions of the hemostasis and fibrinolysis systems, ischemic changes or multifocal ventricular extrasystoles were recorded in the ECG after the second exercise test. These results indicate that intensive physical exercise in postinfarction patients can change the dynamic equilibrium between hemostasis and fibrinolysis in the direction of an increased clotting tendency. For this reason postinfarction patients and elderly untrained persons, especially those with an increased coronary risk factor, should avoid endurance training involving anaerobic exercise. On the other hand, moderate training at aerobic level favorably influences the hemostatic equilibrium in both healthy and postinfarction patients.