Thermoelectric properties of Bi2Te3-Sb2Te3-Sb2Se3 pseudo-ternary alloys in the temperature range 77 to 300° K

The electrical resistivity, thermoelectric power and thermal conductivity of pseudo-ternary Bi₂Te₃-Sb₂Te₃-Sb₂Se₃ alloys were measured in the temperature range 77 to 300° K. From these measurements, figures of merit at various temperatures were calculated and compared with effective figures of merit obtained from the results of Peltier cooling. Best n-type figure of merit, 3.2×10^–3 deg at 300° K, was found at the Bi₂Te₃-rich region of the alloy system and the best room temperature p-type figure of merit, 3.4×10^–3 deg, was obtained at the Sb₂Te₃-rich end. Peltier couples constructed from these alloys reproducibly yielded a maximum cooling of 77.6° K from room temperature. The superior thermoelectric properties of these alloys were attributed to the reduction in the lattice thermal conductivity and its small temperature dependence, and the increase in the energy band gap of the alloys upon additions of Sb₂Se₃.     

BNCT microdosimetry at the tapiro reactor thermal column

A thermal column is available for dosimetric and radiobiological studies by the fast reactor TAPIRO, located at the ENEA research centre Casaccia. The TAPIRO neutron field has been studied (in the frame of LNL BNCT project) with a tissue-equivalent proportional counter, which has worked alternatively with an ordinary tissue-equivalent cathode and with a boron-enriched cathode. Measurements have been performed with polyethylene caps of different thickness. Both the absorbed dose and the microdosimetric-calculated biological effective dose show a maximum at approximately 0.5 mg cm(-2) of depth. The different dose components have been calculated and the results are discussed.     

Characterisation of the TAPIRO BNCT epithermal facility

A collimated epithermal beam for boron neutron capture therapy (BNCT) research has been designed and built at the TAPIRO fast research reactor. A complete experimental characterisation of the radiation field in the irradiation chamber has been performed, to verify agreement with IAEA requirements. Slow neutron fluxes have been measured by means of an activation technique and with thermoluminescent detectors (TLDs). The fast neutron dose has been determined with gel dosemeters, while the fast neutron spectrum has been acquired by means of a neutron spectrometer based on superheated drop detectors. The gamma-dose has been measured with gel dosemeters and TLDs. For an independent verification of the experimental results, fluxes, doses and neutron spectra have been calculated with Monte Carlo simulations using the codes MCNP4B and MCNPX_2.1.5 with the direct statistical approach (DSA). The results obtained confirm that the epithermal beams achievable at TAPIRO are of suitable quality for BNCT purposes.     

Frequency domain electrical conductivity measurements of the passive electrical properties of human lymphocytes

Use of liposomes as carriers of gentamicin for intrabronchial pulmonary delivery was investigated in rabbits. Gentamicin, in isotonic glutamic acid buffer, pH 4.5, was encapsulated in multilamellar vesicles (MLVs) and administered intrabronchially. Higher drug concentrations were found at the pulmonary site of liposome instillation for 1 day as compared with free unencapsulated antibiotic. When time-course distributions of gentamicin given in the liposomal or free form were measured in bronchoalveolar lavages (BAL), similar accumulations were observed up to 4 h, but the drug remained longer (24 h) after administration of the liposomal formulation. Higher amounts of antibiotic were detected in BAL supernatant 1 h after instillation of plain gentamicin; this difference stopped being significant after 4 h. A microbiological assay outlined the bacteriostatic activity of gentamicin released from MLVs and recovered in BAL supernatant. Liposomal gentamicin accumulated in the BAL cell pellet 1 h after intrabronchial instillation; it decreased progressively but minute amounts were still detected after 1 day. On the contrary, no gentamicin was found in the pellet at any time after free drug administration. Comparison of aminoglycoside concentrations in plasma and kidneys indicated lower and constant levels when the liposomal form was instilled. Liposome encapsulation altered the disposition of gentamicin in a way suggesting improved pulmonary concentration and lower systemic toxicity.     

5''-nucleotidase activity in lymphocytes from patients affected by B-cell chronic lymphocytic leukemia

Port site metastasis often occurs after laparoscopic colorectal resection of Dukes B and Dukes C tumors. To evaluate the feasible indication for laparoscopic surgery for the cure of colorectal cancer, we performed a clinicopathologic study with special reference to tumor size. A total of 233 patients who underwent curative resection of colorectal cancer at our department during 15 years were examined. There were 59 Dukes A tumors, and their mean size was 2.86 cm. Tumors < 2 cm, compared with tumors > 2 cm, were characterized by grossly superficial type (68% vs. 9%, p < 0.01), negative serosal invasion (95% vs. 24%, p < 0.01), and absence of lymph node metastasis (91% vs. 60%, p < 0.01). Among tumors < 3 cm, node-negative cases were distinguished by location in the colon (73% vs. 22%, p < 0.05) and by histologically well-differentiated type (75% vs. 11%, p < 0.01) in comparison with node-positive cases. All 14 patients with Dukes A tumor undergoing laparoscopic colectomy were free of recurrence during a mean follow-up period of 34 months. The results indicate that all cancers < 2 cm and well-differentiated colon cancers < 3 cm are good candidates for laparoscopic colorectal surgery for cure.     

Circadian rhythm of cortisol in patients after reconstruction surgery of the esophagus using various intestinal segments for transplantation

The authors determined the circadian rhythm of cortisol expressed as blood 11-hydroxycorticosteroid level (11 OHCS) in group of healthy subjects and in 3 groups of patients after the formation of an artificial oesophagus from the jejunum, large intestine and ileum and caecum. In all examined patients the normal circadian rhythm of 11 OHCS was maintained. In patients with oesophagus made up of jejunum and large intestine mean level 11 OHCS in blood was insignificantly higher in comparison with a group healthy subjects. In group patients with the oesophagus made up of ileum and caecum the 11 OHCS level in blood was significantly lower in comparison to the group of healthy subjects and to patients with oesophagus made up of jejunum and large intestine.     

Fiber-optic fourier transform mid-infrared reflectance spectroscopy: a suitable technique for in situ studies of mural paintings

A prototypical in situ noninvasive study of ancient mural painting materials has been carried out using an easily manageable fiber-optic Fourier transform mid-infrared (mid-FT-IR) reflectance spectrophotometer. The reported object of the study is the Renaissance fresco by Pietro Vannucci, called il Perugino, located in the church of Santa Maria delle Lacrime (1521, Trevi, Perugia Italy). For the first classification and interpretation of infrared spectra, principal components analysis was used. Spectral artifacts due to lacunas, restoration materials, or alteration products have been identified, as well as two different secco refinements bound in a tempera medium. For the characterization of inorganic pigments, mid-FT-IR spectra have been integrated with other data obtained through in situ X-ray fluorescence (XRF) elemental analysis. This complementary noninvasive approach led to the characterization of Perugino's pigments, even in the presence of complex mixtures. The mid-FT-IR noninvasive technique, in combination with XRF, is thus recommended as a valuable first approach for the examination of mural paintings, permitting the assessment of the execution technique as well as contributing to the evaluation of the conservation state.