Dielectric relaxation and anhydrous proton conduction in [C2H5NH3][Na0.5Fe0.5(HCOO)3] metal-organic frameworks.

Metal-organic frameworks (MOFs), in which metal clusters are coupled by organic moieties, exhibit inherent porosity and crystallinity. Although these systems have been examined for vast potential applications, the elementary proton conduction in anhydrous MOFs still remains elusive. One of the approaches to deal with this problem is the utilization of protic organic molecules, to be accommodated in the porous framework. In this work we report the temperature-dependent crystal structure and proton conduction in [C2H5NH3][Na0.5Fe0.5(HCOO)3] metal-organic frameworks using X-ray diffraction and broadband dielectric spectroscopic techniques. The detailed analysis of the crystal structure reveals disorder of the terminal ethylene groups in the polar phase (space group Pn). The structural phase transition from Pn to P21/n at T ≈ 363 K involves the distortion of the metal formate framework and ordering of EtA+ cations due to the reduction of the cell volume. The dielectric data have been presented in the dynamic window of permittivity formalism to understand the ferroelectric phase transition. The relaxation times have been estimated from the Kramers-Kronig transformation of the dielectric permittivity. A Grotthuss type mechanism of the proton conduction is possible at low temperatures with the activation energy of 0.23 eV. This type of experimental observation is expected to provide new prospective on the fundamental aspect of elementary proton transfer in anhydrous MOFs.

Dielectric relaxation behavior in antiferroelectric metal organic framework [(CH3)2NH2][Fe(III)Fe(II)(HCOO)6] single crystals.

The fundamental aspects of the relaxation dynamics in niccolite-type, mixed valence metal-organic framework, multiferroic [(CH3)2NH2][Fe(3+)Fe(2+)(HCOO)6] single crystals have been reported using dielectric relaxation spectroscopy covering eight decades in frequency (10(-2) ≤ f ≤ 10(6)) in the temperature range 120 K ≤ T ≤ 250 K. The compound shows antiferroelectric to paraelectric phase transition near T = 154 K with the relaxor nature of electric ordering. The temperature dependent dielectric response in modulus representation indicates three relaxation processes within the experimental window. The variable range hopping model of small polarons explains the bulk non-Debye type conductivity relaxation. The fastest relaxation with activation energy Ea = 0.17 eV is related to progressive freezing of the reorientation motions of DMA(+) cations. X-ray diffraction data revealed that complete freezing of orientational and translational motions of DMA(+) cations occurs well below phase transition temperature. These experimental observations are fundamentally important for the theoretical explanation of relaxation dynamics in niccolite-type metal-organic frameworks.

Ultrafast Optical Properties of Dense Electron Gas in Silicon Nanostructures.

We investigate the ultrafast dynamics of carriers in a silicon nanostructure by performing spectrally resolved femtosecond spectroscopy measurements with a supercontinuum probe. The nanostructure consists of a 158-nm-thick crystalline Si layer on top of which a SiO2 passivation layer leads to a very high quality of the Si surface. In addition, a dielectric function approach, including contributions from a Drude part and interband transitions, combined with the Transition Matrix Approximation is used to model the photogenerated carrier dynamics. The spectrotemporal reflectivity reveals two mechanisms. First, an electron-hole plasma is created by the pump pulse and lasts for a few picoseconds. Importantly, its spectral signature is either a positive or a negative change of reflectivity, depending on the probe wavelength. This is complementary to the already reported results obtained with degenerate frequency measurements. The second mechanism is a thermal diffusion of carriers which occurs during several hundreds of picoseconds. The overall dynamics at short and long delays in the whole visible spectrum is well explained with our model which shows that the main contribution to the reflectivity dynamics is due to the Drude dielectric function. The observation of this predominance of free carriers requires both a long lived high density of carriers as well as a little influence of surface scattering as provided by our thin crystalline Si layer with passivated Si/SiO2 interface.

Effects of Carrier Confinement and Intervalley Scattering on Photoexcited Electron Plasma in Silicon.

The ultrafast reflectivity of silicon, excited and probed with femtosecond laser pulses, is studied for different wavelengths and energy densities. The confinement of carriers in a thin surface layer delimited by a nanoscale Si-layered system buried in a Si heavily-doped wafer reduces the critical density of carriers necessary to create the electron plasma by a factor of ten. We performed two types of reflectivity measurements, using either a single beam or two beams. The plasma strongly depends on the photon energy density because of the intervalley scattering of the electrons revealed by two different mechanisms assisted by the electron-phonon interaction. One mechanism leads to a negative differential reflectivity that can be attributed to an induced absorption in X valleys. The other mechanism occurs, when the carrier population is thermalizing and gives rise to a positive differential reflectivity corresponding to Pauli-blocked intervalley gamma to X scattering. These results are important for improving the efficiency of Si light-to-electricity converters, in which there is a possibility of multiplying carriers by nanostructurization of Si.

[Urinary trehalase activity as an indicator of renal dysfunction in lead smelters]. / Stezenie trehalazy w moczu jako wskaznik dysfunkcji nerek osób zawodowo narazonych na dzialanie olowiu.

Epidemiological and experimental studies have demonstrated that lead and cadmium are responsible for renal dysfunction. Urinary trehalase is known as a good marker of proximal tubular renal brush border destruction in the population environmentally exposed to cadmium. The aim of this study was to determine the impact of occupational exposure to lead on the renal function and urinary trehalase activity. The study was carried out in 68 workers, aged 46 +/- 6 years, employed in a copper foundry. Blood lead, cadmium, copper and manganese concentrations were measured by atomic absorption spectrophotometry. Urinary trehalase activity was determined by the method of Nakano and Itoh. Trehalase activity was increased in copper smelters as compared to controls. There also was a positive linear correlation between blood lead level and urinary trehalase activity (r = 0.44; p < 0.05). Negative correlations between blood lead and copper concentrations (r = -0.30; p < 0.05) and between serum copper and trehalase level (r = 0.68; p < 0.001) were found. The results show that urinary trehalase activity could be a good indicator of the renal brush border dysfunction in copper smelters. This marker could be useful in the early diagnosis of nephrotoxic effect of lead.

[Serum selectin E level in lead-exposed workers]. / Selektyna E w surowicy osób zawodowo narazonych na dzialanie olowiu.

Lead is recognised as a potential atherogenic factor. One of the earliest events in the development of atherosclerosis is monicyte attachment to the endothelial surface. This is followed by recruitment of monocytes into the subendothelial space and ingestion of modified LDL by these cells. In turn, modified LDL stimulates endothelial cells to induce expression of proinflammatory adhesion molecules, such as selectins, which further promote monocyte migration. It was observed that atherosclerotic vascular damage is associated with increased level of circulating selectin E. The aim of this study was to determine the impact of the occupational exposure to lead on the serum selectin E level. The study involved 80 patients, including 37 workers of a copper foundry and 43 people not exposed to lead. The subjects were matched in pairs according to sex, age and cholesterol concentration in blood. There were 25 hipercholesterolemic pairs and 9 pairs with normal serum total cholesterol. People exposed to lead had higher (about 7 ng/ml) serum selectin E concentration than those not exposed. There was positive linear correlation between selectin E and triglycerides in the whole group (p < 0.01), and the strongest correlation was observed in the group of subjects not exposed to lead (aged 40-60, r = 0.74). In the context of the described hypertriglyceridemic action induced by lead, these results suggest that lead could potentially act as an atherogenic factor in the early, inflammatory stage of atherosclerosis.

[Effect of arsenic and its compounds on the circulatory system]. / Wplyw arsenu na uklad krazenia.

Arsenic is a metal which occurs widely in both occupational and physical environments. Therefore, its easy accessibility and high toxicity raise the question on whether arsenic, particularly in relatively small doses, can cause damage of relevant molecular, biochemical and clinical significance to the cardiovascular system. The present review is focused on the confirmed and potential mechanisms of arsenic effect on the function and structure of vascular endothelium (nitric oxide, peroxynitrite), its role in stimulating the oxidative species formation (hydroxyperoxide, superoxide and lipid peroxide formation), as well as in decreasing the antioxidative response (enzymes: superoxide dysmutase, catalase, glutation peroxidase), its cytotoxic effects, including immunotoxic properties, arsenic action in the signal transduction pathways network (kinases and DNA transcription factors), impact on cell proliferation, differentiation and apoptosis, not to mention its interference with DNA synthesis and repair processes. Apart from mechanisms of arsenic action, the article provides the up-to-date information on various cardiovascular diseases of the established or presumed arsenic origin.

[The results of surgical treatment of patients with laryngeal carcinoma in years 1988-1989 in four departments of otorhinolaryngology]. / Wyniki operacyjnego leczenia chorych na raka krtani w latach 1988-1989 w czterech osrodkach klinicznych.

In a group of 579 patients with laryngeal carcinoma treated surgically in years 1988-1989 in four departments of otorhinolaryngology of the Medical Academies in Poznan, Warsaw, Cracow and Lublin, 72% survived 3 years without recurrence and 59% survived 5 years. Similar results were obtained in years 1986-1987. The authors discuss in detail the reasons for failures of the surgical treatment, i.e.: supraglottic localization of the cancer, its extensiveness in the larynx, the stage of clinical development, general condition of the patient, effectiveness of the operation, regularity of postsurgical examination, the degree of histological malignancy, blood transfusion during the operation, distant metastases, little efficiency of medical service in early diagnosis of laryngeal cancer, avoiding postsurgical radiation, subjective factors of the patients and the choice of the optimal method of the treatment. Few patients can be cured if the initial treatment fails.

[Therapeutic and diagnostic difficulties with parapharyngeal tumors]. / Trudnosci diagnostyczne i lecznicze u chorej z duzym guzem przestrzeni przygardlowej.

Tumors of the parapharyngeal space are not very common. The case with big tumor of the parapharyngeal space was described, primary misdiagnosed as the tumor of the parapharyngeal tonsil and then as the tumor of the soft palate. The tumor was removed finally from the external parotido-cervical approach.

[Efficiency of surgical treatment in patients with laryngeal cancer depending on age]. / Wydolnosc operacyjnego leczenia chorych na raka krtani w zaleznosci od wieku.

In the group of 578 patients with larynx cancer that underwent surgical treatment in four clinics of Medical Academies between 1986-87 a comparable analysis of the efficiency of surgical treatment depending on age of the operated patients was carried out. It was found that the difference between age average and the general state of patients was statistically highly important: Statistically significant was also the dependence between the patients' age and the postoperative complications; close to importance was also the dependence between the age and the survival period of patients. 68% of operated patients up to 65 year of age had five-year survival period without any symptoms; but in the group of patients over 65 years of age the analogical survival value was 51%.

[The clinical significance of metastatic cancer of the larynx to the Delphi node]. / Kliniczne znaczenie przerzutu do wezla delfickiego w raku krtani.

Between years 1965-1987, 920 patients with cancer of the larynx were operated on. In this time we identified 9 cases of histologically proven metastasis to the Delphian node. In all patients except one, the neck was clinically negative but a positive Delphian node was discovered at partial or total laryngectomy. Five patients developed metastasis postoperative. Seven of 9 patients have died from their laryngeal cancer. The frequency of neck metastasis and local recurrences is very high in patients with a positive Delphian node.

[The treatment of subglottic defect with the help of myoperisteal flap from sternum]. / Zastosowanie uszypulowanego plata okostnowego z mostka w zwezniach podglosniowych krtani.

Reconstruction of subglottic defect with the help of sternocleidomastoid myoperiosteal flap was performed in 6 patients. Four of them were successfully decannulated. The average time from reconstruction to decannulation was 67 days. Technic of operation was described and discussed in light of our own and literature experiences.

[Efficiency of surgical treatment in patients with laryngeal cancer in four clinical centers]. / Wydolnosc operacyjnego leczenia chorych na raka krtani w czterech osrodkach klinicznych.

A group of 578 patients with larynx cancer underwent surgical treatment in four Otolaryngological Clinics of Medical Universities in Poznan, Warsaw, Cracow and Lublin between 1986-1987. Within this group, 75% of operated patients had a three--year survival rate without symptoms, and 58% of patients had a five-year survival rate. A detailed evaluation of causes of failures in surgical treatment dealt with e.g. the initial placement of the cancer including entrance margins of larynx in a rich net of lymphatic vessels, extensiveness of organs, the degree of clinical progressions, general physical condition of a patient, radicality of treatment, regularity of check-ups after the operation, high degree of histological malignancy unfavourable configuration of TNM feature blood transfusions, the appearance of remote metastases low efficiency in the early diagnostics of larynx cancer, subjective conditions of patients, discontinuation of complementary irradiation.

[Analysis of the causes of failure in surgical treatment of cancer of the larynx]. / Analiza przyczyn niepowodzen leczenia operacyjnego chorych na raka krtani.

In the years 1985-1990 within the group of 2769 patients operated upon for laryngeal cancer in four medical centres (Kraków, Poznan, Warszawa, Lublin), a clinical analysis on surgical treatment failures was performed. The most significant reasons of failures were: the highly advanced age of patients, coexistent diseases, in particular the cardiopulmonary disease; poor information of neoplastic diseases (carcinomas) and delayed referral to the doctor; lack of consent for surgical treatment; old fashioned diagnostic methods; prolonged period of making diagnosis; increasing number of patients with supra-glottic localization including the hypo-pharynx and piriform recess; a considerable degree of organ ++cancer advancement and substantial clinical advancement; not radical excision of neck glands; intra-surgical blood transfusion; micrometastases to lymphatic glands; immunity collapse; discontinuance of post-surgical radiation on affected parts; lack of lymphadenectomy backward from accessory nerve ; massive cancer metastases to lymph nodes; high histologic malignancy with characteristic carcinous invasiveness; and finally, surgical and post-surgical early and late complications ranginy within our material from 25% to 29% of surgical patients. Basing on the above mentioned analysis, the authors developed indications for surgical treatment of laryngeal cancer.

[Evaluation of the effectiveness of surgical treatment of metastases of laryngeal cancer to the lymph nodes]. / Ocena wydolnosci leczenia operacyjnego przerzutów raka krtani do wezlów chlonnych.

The evaluation of surgical treatment results was done to 308 oncological patients to whom metastases were formed in lymph nodes between 1980-1984, following the previous surgical treatment of the laryngeal cancer. The evaluation included among others the following: cancer initial localization: T and N traits; the degree of malignancy; surgical radical intervention ; assertion of neoplastic cell plugs in vessels; the time of recurrent lymphatic metastases, etc. The efficiency of surgical treatment of metastases being formed following the previous surgical treatment of laryngeal cancer, measured by the time of 5 years asymptomatic life, equalled 33.4% in the discussed material. Moreover, it was stated that in the studied group of 308 patients the percentage of deaths was increasing in the subsequent years of taking observations (from 1980 to 1984) and depended also on patients overall condition, initial cancer localization, the degree of neoplastic advancement and on the degree of cancer histologic malignancy.

[Evaluation of the causes of lymphatic metastases after surgical treatment of patients with laryngeal cancer]. / Ocena przyczyn powstawania przerzutów do wezlów chlonnych po leczeniu operacyjnym chorych na raka krtani.

During the years 1980-1988 2458 laryngeal cancer patients were operated upon in 4 ENT AM Clinics in Kraków, Poznan, Lublin and Warszawa. 300 (12%) out of them have had the cervical node metastases in 18 months after the surgery. The cause analysis was performed. The primary localizations were in the epiglottic and ++post-cricoid areas. The causes of metastases to the ++lymph nodes were analyzed; the primary epiglottic and ++post-cricoid localization of the tumor, its extensiveness and advanced clinical stage. Twice more often were the nodal metastases stated before the primary treatment, a high degree of histological malignancy, probably insufficient radicality of the surgery and insufficient immunological resistance of the organism were taken in consideration. This group of patients presented a rather high percentage of early unsuccessful results of surgical treatment of the laryngeal cancer; this problem needs further analysis and observations.

[Evaluation of complications after surgical treatment of cancer of the larynx]. / Ocena powiklan po leczeniu operacyjnym chorych na raka krtani.

The surgical complications in a group of 1712 laryngeal cancer patients treated during the years 1981-87 in ENT Clinics of Cracow, Poznan, Warsaw and Lublin were described. The most dangerous were bleedings and the most frequent wound and tracheo-+-bronchial infections and pharyngo-cutaneous fistulas++, after radical neck dissection however the paralysis of sublingual and accessory nerves and of brachial plexus. The predisposing factors were: diabetes, lung and heart diseases, late stage of cancer, extent of surgery and tumor infections.