Approaching theoretical strength in glassy carbon nanolattices.

The strength of lightweight mechanical metamaterials, which aim to exploit material-strengthening size effects by their microscale lattice structure, has been limited by the resolution of three-dimensional lithography technologies and their restriction to mainly polymer resins. Here, we demonstrate that pyrolysis of polymeric microlattices can overcome these limitations and create ultra-strong glassy carbon nanolattices with single struts shorter than 1 µm and diameters as small as 200 nm. They represent the smallest lattice structures yet produced--achieved by an 80% shrinkage of the polymer during pyrolysis--and exhibit material strengths of up to 3 GPa, corresponding approximately to the theoretical strength of glassy carbon. The strength-to-density ratios of the nanolattices are six times higher than those of reported microlattices. With a honeycomb topology, effective strengths of 1.2 GPa at 0.6 g cm(-3) are achieved. Diamond is the only bulk material with a notably higher strength-to-density ratio.

Mechanical characterization between room temperature and 1000 °C of SiC free-standing thin films by a novel high-temperature micro-tensile setup.

A novel high-temperature micro-tensile setup allows the characterization of the elastic and plastic as well as creep behavior of free-standing thin films at temperatures of up to 1000 °C. Correspondingly, a new layout for free-standing thin film tensile test structures has been developed, enabling accurate self-alignment upon loading. Furthermore, a differential optical strain measurement technique as well as optimizations of the optical path has been implemented, providing a strain resolution of well below 1 × 10(-4) at 1000 °C. Two different polycrystalline SiC free-standing thin films have been investigated in tension to acquire stress-strain data and corresponding Young's modulus at up to 1000 °C. The high sensitivity of the strain measurement technique makes it also possible to identify creep strains in the high-temperature regime.

In situ nanomechanical testing in focused ion beam and scanning electron microscopes.

The recent interest in size-dependent deformation of micro- and nanoscale materials has paralleled both technological miniaturization and advancements in imaging and small-scale mechanical testing methods. Here we describe a quantitative in situ nanomechanical testing approach adapted to a dual-beam focused ion beam and scanning electron microscope. A transducer based on a three-plate capacitor system is used for high-fidelity force and displacement measurements. Specimen manipulation, transfer, and alignment are performed using a manipulator, independently controlled positioners, and the focused ion beam. Gripping of specimens is achieved using electron-beam assisted Pt-organic deposition. Local strain measurements are obtained using digital image correlation of electron images taken during testing. Examples showing results for tensile testing of single-crystalline metallic nanowires and compression of nanoporous Au pillars will be presented in the context of size effects on mechanical behavior and highlight some of the challenges of conducting nanomechanical testing in vacuum environments.

A new method to measure torsion moments on small-scaled specimens.

As a result of a continuous evolution in the field of small-scaled components, an increasing need exists for mechanical characterization of single structures and materials in micrometer dimensions. Moreover, for a detailed analysis of the deformation and failure behavior, it is often necessary to perform investigations under multiaxial loading in addition to uniaxial loading. A simple possibility to create defined multiaxial stress-strain fields is offered by a torsion experiment. In the frame of this work, a new method is presented, which allows determining torsion moments applied to wires as thin as 10 µm in monotonic as well as cyclic manner. Besides a detailed description of the measuring principle, the experimental setup and the first results will be presented. In particular, investigations on gold wires with diameters ranging from 10 to 60 µm, applying torsion moments in the nNm regime, are shown.

Correlation between critical temperature and strength of small-scale bcc pillars.

Microcompression tests were performed on focused-ion-beam-machined micropillars of several body-centered-cubic metals (W, Mo, Ta, and Nb) at room temperature. The relationship between yield strength and pillar diameter as well as the deformation morphologies were found to correlate with a parameter specific for bcc metals, i.e., the critical temperature T(c). This finding sheds new light on the phenomenon of small-scale plasticity in largely unexplored non-fcc metals.

[Lymphatic mapping in cervical cancer]. / Lymfatické mapování u karcinomu cípku delozního.

BACKGROUND AND AIMS: The aim of the study is to analyze the feasibility of intraoperative sentinel lymph nodes (SLN) detection using gamma detection probe and blue dye in patients with cervical cancer. DESIGN AND SUBJECTS: Prospective clinical study. 106 patients with cervical cancer were included into the study in the period from May 2004 to November 2006. METHODS AND RESULTS: Patients were divided into three groups according to the tumor volume. Lymphoscintigraphy was performed following an injection of 99m Tc-labeled nanocolloid and intraoperatively the SLN were identified visually after marking of lymphatic vessels with blue dye and further detected using a handheld gamma detection probe. The SLN were histologically and immunohistochemically analyzed. Total number of 309 SLN with an average of 2.9 per patient were identified. The SLN detection rate was 94.3% per patient, 84.4 % per side, and depended on the tumor volume. Metastatic disease was detected in 39 patients (36.8%) and micrometastatic disease in 15 patients (14.2%). Sensitivity and negative predictive value calculated were 93.9% and 98.0%, false negative rate reached 5.1. CONCLUSIONS: Intraoperative detection of SLN using combination of technecium-99-labeled nanocolloid and blue dye represents a feasible, safe and accurate technique to identify lymphatic spreading in stages IA2-IB1 of cervical cancer.

Preparation and quality control of [166Ho]-macroaggregates for radiosynoviorthesis.

(166)Ho is a beta-emitter (E(_max) = 1.84 MeV, T1/2 = 26.7 hours) with a mean penetration in the soft tissue of 2.2 mm and gamma-photons 81keV and 1380keV. In this paper, we present our experiences with preparation of (166)Ho-macroaggregates ((166)Ho-MA) for radiosynoviorhesis. Ho-MA were prepared by reacting the aqueous solution of holmium nitrate pentahydrate with sodium borohydride solution in 0.2 M NaOH. After centrifugation, washing, and drying at 105 degrees C, final fineness of 1-15 microm was attained using a homogenizer working at 70,000 rpm. Neutron activation was carried out in screwed titanium ampules in a nuclear reactor at the neutron flux 10E12-10E14 neutrons.cm-24.s-1. The irradiated samples were allowed to cool 24 hours before further manipulation. (166)Ho-MA were clinically tested on 20 patients suffering from gonarthrosis (15), rheumatoid arthritis (5), psoriatic arthritis (1), and gout arthropathy (1). (166)Ho-MA are currently produced under GMP and production facility allows producing radioactivity for 6 patients within one production run.

[Sentinel node detection in early stage of cervical carcinoma using 99mTc-nanocolloid and blue dye]. / Detekce sentinelové uzliny u casných stadií cervikálního karcinomu kombinovanou metodou s uzitím nanokoloidu technecia Tc99 a patentní modri.

OBJECTIVE: The aim of the study was to analyse the feasibility of intraoperative sentinel lymph nodes (SLN) detection using gamma detection probe and blue dye in patients undergoing radical hysterectomy for treatment of early stage of cervical cancer. DESIGN: Prospective case observational study. METHODS: In the period from May 2004 to February 2006 77 patients with early stage of cervical cancer who underwent a radical surgery were included into the study. Patients were divided into three groups according to the tumour volume. First group consists of patients FIGO IA2 and FIGO IB1 with tumour diameter less than 2 cm, second group tumours FIGO IB1 with tumour diameter more than 2 cm and third group stadium IB2. SLN was detected by blue dye and Tc99. Preoperative lymphoscintigraphy was done after Tc99 colloid injection, intraoperative detection was performed by visual observation and by hand-held gamma-detection probe. SLN were histologically and immunohistochemically analysed. RESULTS: A total number of 2764 lymph nodes with an average 36 and 202 SLN with an average 2.6 were identified. The SLN detection rate was 94.8% per patient and 85.1% for the side of dissection and depends on the tumor volume. SLN were identified in obturator area in 48%, in external iliac area in 15%, in common iliac and internal iliac both in 9%, in interiliac region in 8%, in praesacral region in 6% and in parametrial area in 5%. Metastatic disease was detected in 31 patients (40.2%), metastatic involvement of SLN only in 12 patients (15.6%). False negative rate was 2.6%, sensitivity and negative predictive value calculated by patient were 923% and 95.7%. CONCLUSIONS: Intraoperative lymphatic mapping using combination of technecium-99-labeled nanocolloid and blue dye are feasible, safe and accurate techniques to identified SLN in early stage of cervical cancer.

[Lymphatic mapping and detection of sentinel node in early stages of cervical carcinoma]. / Lymfatické mapováni a detekce sentinelové uzliny u casných stadií cervikálního karcinomu.

OBJECTIVE: The aim of the study was to analyse two methods of intraoperative sentinel node detection using blue dye and blue dye with Tc99 labeled tracer in early stage of the cervical cancer. DESIGN: Prospective case observational study. SETTING: Department of Obstetrics and Gynecology, University Hospital Ostrava. METHODS: From May 2004 to September 2005, 49 patients with cervical cancer who underwent a radical surgery were included into the study. Sentinel lymph node was detected using blue dye in the first group of 23 patients and by blue dye with Tc99 in the second group of 26 patients. Intraoperative sentinel node detection was performed by visual aspection in the first group, and by visual aspection and by hand-held gamma-probe in the second group. RESULTS: Patients were divided according to stage of the disease into three subgroups FIGO IA2, FIGO IB1 and FIGO IB2. A total number of 1561 lymph node with an average 32 and 94 SLN with an average 1.9 were identified. The specific detection rate per site was 63% in the first group and 80.8% in the second group respectively. Metastatic disease was detected in 26 patients (41%) and metastatic involvement of SLN only in 11 patients (17.4%). Sensitivity and negative predictive value were 100% in both groups, false negativity was 0%. CONCLUSION: Detection of SLN by combination of blue dye and Tc99 labeled tracer has a higher detection rate of SLN than detection by blue dye alone.

[Problems of detection and biopsy examination of sentinel lymph nodes in malignant melanomas and in breast carcinoma]. / Problematika detekce a biopsie sentinelové uzliny u maligních melanomu a karcinomu prsu.

BACKGROUND: Detection of SLN in some types of malignant tumors is important for the developing of a therapeutic strategy, determining the stage and predicting prognosis. It is possible to avoid removal of whole groups of lymph nodes. We have three detection methods--lymphoscintigraphy, blue dye and gamma probe. The aim of this study was to compare these methods in breast cancer and malignant melanoma patients, to compare three radiopharmaceuticals, to assess the detection of non-axillary SLN in breast cancer. METHODS AND RESULTS: SLN were examined in 214 melanoma patients (94 men, average age 58.4 yrs; 120 women, average age 52.6 yrs), in 147 breast cancer patients (145 women and 2 men, average age 59.3 yrs). We used combination of lymphoscintigraphy, intraoperative blue dye and gamma probe. Lymphoscintigraphy was done with three radiopharmaceuticals--Nanocis, Senti-Scint and Nanocoll. SLN were subjected to histological and immunohistochemical examination. The best success rate of detection of SLN was by means of lymphoscintigraphy and the lowest by blue dye. The differences among the three radiopharmaceuticals were not large, however, in average Nanocoll detected more SLNs in malignant melanoma patients. In the breast cancer patients the false-negative rate of SLN was 5.17%, sensitivity 94.83%, negative predictive value 96.7%, accuracy 98%, positive predictive value 100%, specificity 100%. CONCLUSIONS: Parallel use of scintigraphy. gamma probe, and blue dye is the highly effective and indispensable for the SLN detection. In breast cancer patients it is advisable to take biopsy samples from the displayed non-axillary SLNs for improving the effects of the method.

[Determination of differential renal function using dynamic scintigraphy]. / Problematika stanovení separované funkce ledvin pomocí dynamické scintigrafie.

By examination of 71 patients, using static and dynamic scintigraphy of the kidneys, the authors tested whether dynamic scintigraphy provides correct results of the separate renal function in case of a symmetrical localization of the kidneys. In case of slight asymmetry the error of calculation is feasible. In case of major differences in the position of the kidneys the results cannot be used for clinical purposes. In these patients static scintigraphy must be used with correction for different absorption layers.

[Functional activity of a metastatic differentiated carcinoma of the thyroid gland]. / Funkcne aktiviní metastáza diferencovaného karcinomu stítné zlázy.

In a patient with differentiated thyroid carcinoma of the follicular type after removal of the thyroid gland and nodular secondaries on the neck a functional secondary was detected in the liver by combined whole-body scintigraphy following administration of 131-I and scintigraphy of the liver using 99mTc-colloid, supplemented by scintigraphy of the skeleton following administration of 99mTc-MDP. At first the high thyroglobulin serum level was after repeated radioiodine treatment falsely negative. The author presents a review of cases reported in the literature who suffered from this rare type of secondaries.

[Determination of differential renal function using 99m Tc-DMSA scintigraphy]. / Problematika stanovení separované funkce ledvin pomocí scintigrafie po podání 99m Tc-DMSA.

By examination of 331 patients, using 99mTc-DMSA, the authors confirmed that static scintigraphy is an accurate method for assessment of the separate renal function. In four groups of patients with different positions of the kidneys the authors proved that correction for different absorption of gamma radiation from the left and right kidney is essential. Without correction results with a significant error are obtained, in particular in patients with an asymmetric position of the kidneys, where the results calculated without correction cannot be used for clinical purposes. The results are not influenced by the time interval between administration of the radiopharmaceutical preparation and examinations within an interval of 2 to 4 hours, with the exception of patients with severe obstructive uropathy. For assessment of the relative function of the kidneys it is better to examine the patient in a vertical position. The reproducibility of results in repeated examinations and repeated evaluation is excellent.

[Scintigraphic determination of the function of an autotransplanted spleen]. / Scintigrafický prukaz funkce autotransplantované sleziny.

In an 8-year-old boy after abdominal injury scintigraphically, using radiocolloid labelled 99mTc, suspicion of a ruptured spleen was confirmed. Therefore splenectomy was performed and an autotransplantation of a portion of the spleen into the great omentum. After three months during scintigraphy performed with autologous thermally damaged and indium 113mIn labelled erythrocytes a small functional autotransplant of the spleen on the left side of the navel was revealed. Twelve months after operation scintigraphy confirmed its vitality and even an increase in size. Scintigraphy by means of damaged and labelled erythrocytes is the only visualization method to reveal vitality and functioning of autotransplants of the spleen.

[Antibodies against thyroxine, triiodothyronine and thyroglobulin as a possible cause of error in the diagnosis of disorders of thyroid gland function]. / Protilátky proti tyroxinu, trijodtyroninu a tyreoglobulinu jako mozná prícina omylu pri diagnostice poruch funkce stítné zlázy.

The authors examined in a 82-year-old female patient T4, T3, free T4, TSH, thyroglobulin and made the TRH-TSH functional test because of suspected thyroid disease. For thyroid hormones they obtained controversial resulting levels: in T4 signalizing an unreasonable negative value, in T3 a very high level, in TSH and the TRH-TSH test levels suggesting normal thyroid function which was consistent with the clinical picture. A more detailed laboratory analysis revealed the presence of antibodies binding 125I-T4 and 125I-T3 (radioindicators used for assessment of T4 and T3). The authors identified antibodies against T4, T3 and thyroglobulin. Their presence influenced the radioimmunoassay of T4 and T3 and also the immunoradiometric estimation of thyroglobulin (artificially raised level). The reliable result of the eufunctional condition was not influenced in the estimation of the TSH level.

Prostaglandin synthesis along the gastrointestinal tract of the rabbit: differences in total synthesis and profile.

In the present study we systematically investigated the synthesis of prostaglandins in the mucosa and the muscle layer along the length of the rabbit gut. Homogenates of mucosa and muscle layer were incubated with (14C)-labelled arachidonic acid, and prostaglandin formation was determined using thin-layer chromatography. With respect to total prostaglandin synthesis the highest values in the mucosa were measured in fundus, antrum and colon, whereas the prostaglandin synthesis in the muscle layer was maximal in the small bowel, particularly the ileum. In the mucosa, the prostaglandins E2 and F2a predominated, and there were minor differences along the gastrointestinal tract. In the muscle layer of the stomach, high amounts of 6-keto prostaglandin F1a, the stable degradation product of prostacyclin were produced, while small and large bowel homogenates synthesized mostly F2a. Consistently the prostaglandins A2/B2 were a major product in most locations. In addition, PG E2 catabolism to 15-keto PG E2 and 13,14-dihydro-15-keto PG E2 in the absence of NAD was slow. No significant changes in total prostaglandin synthesis and prostaglandin profile were detected between 24 hrs fasted and normally fed rabbits at any part of the gastrointestinal tract.

Design hazards of electrosurgical devices.

The tremendous lifesaving value of adjunct electrosurgery to the medical profession is not without potential hazards. The hazards, which can be classified as radio-frequency burn hazards, shock hazards, electrocution hazards, and explosion hazards, may result from equipment design circuitry, possible failure modes, or operator error. The three basic electrosurgery systems currently being marketed--grounded output systems, referred-to-ground output systems, and floating output systems--are described, and the hazard potential of each system, as well as the hazard potentials of modifications of these systems, are identified. The authors propose a safety system to eliminate most of the hazards cited for the other systems, recommend minimum circuit performance requirements, and evaluate an electrosurgery standard.