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A Grzybowski

Publications and source records attributed to A Grzybowski.

At least 19 recordsLinked to original sources
PubMed2006

Correlations between isobaric and isochoric fragilities and thermodynamical scaling exponent for glass-forming liquids.

Two correlations concerning the isobaric and isochoric fragilities, m(P) and m(V), as well as the scaling exponent gamma reported by Casalini and Roland [Phys. Rev. E 72, 031503 (2005)] have been examined for several van der Waals and hydrogen-bonded glass formers. It has been pointed out that the correlations lead to some serious inconsistency with the exponent gamma, which is expected to be a constant dependent only on material, but varies also on pressure if experimentally found pressure dependences of m(P) are taken into account. This problem could be solved in the case of van der Waals liquids, but then at least one of the correlations becomes dependent on thermodynamic conditions, and consequently, loses its universality. However, some H-bonded systems, due to properties of hydrogen bonding, have been well argued not to be included to determine the correlations independently of thermodynamic conditions. Furthermore, it has been noticed that another correlation concerning the fragility, between m(P) and the structural relaxation peak breadth, yields discrepancies in comparison with results of experiments under elevated pressure.

Journal Article↗
PubMed2006

Computer simulation of the linear and nonlinear optical susceptibilities of p-nitroaniline in cyclohexane, 1,4-dioxane, and tetrahydrofuran in quadrupolar approximation. II. Local field effects and optical susceptibilitities.

This is the second part of a study to elucidate the local field effects on the nonlinear optical properties of p-nitroaniline (pNA) in three solvents of different multipolar character, that is, cyclohexane (CH), 1,4-dioxane (DI), and tetrahydrofuran (THF), employing a discrete description of the solutions. By the use of liquid structure information from molecular dynamics simulations and molecular properties computed by high-level ab initio methods, the local field and local field gradients on p-nitroaniline and the solvent molecules are computed in quadrupolar approximation. To validate the simulations and the induction model, static and dynamic (non)linear properties of the pure solvents are also computed. With the exception of the static dielectric constant of pure THF, a good agreement between computed and experimental refractive indices, dielectric constants, and third harmonic generation signals is obtained for the solvents. For the solutions, it is found that multipole moments up to two orders higher than quadrupole have a negligible influence on the local fields on pNA, if a simple distribution model is employed for the electric properties of pNA. Quadrupole effects are found to be nonnegligible in all three solvents but are especially pronounced in the 1,4-dioxane solvent, in which the local fields are similar to those in THF, although the dielectric constant of DI is 2.2 and that of the simulated THF is 5.4. The electric-field-induced second harmonic generation (EFISH) signal and the hyper-Rayleigh scattering signal of pNA in the solutions computed with the local field are in good to fair agreement with available experimental results. This confirms the effect of the "dioxane anomaly" also on nonlinear optical properties. Predictions based on an ellipsoidal Onsager model as applied by experimentalists are in very good agreement with the discrete model predictions. This is in contrast to a recent discrete reaction field calculation of pNA in 1,4-dioxane, which found that the predicted first hyperpolarizability of pNA deviated strongly from the predictions obtained using Onsager-Lorentz local field factors.

Aniline Compounds↗
PubMed2006

Dielectric secondary relaxations in polypropylene glycols.

Broadband dielectric measurements of polypropylene glycol of molecular weight M(w)=400 g / mol (PPG 400) were carried out at ambient pressure over the wide temperature range from 123 to 353 K. Three relaxation processes were observed. Besides the structural alpha relaxation, two secondary relaxations, beta and gamma, were found. The beta process was identified as the true Johari-Goldstein relaxation by using a criterion based on the coupling model prediction. The faster gamma relaxation, well separated from the primary process, undoubtedly exhibits the anomalous behavior near the glass transition temperature (T(g)) which is reflected in the presence of a minimum of the temperature dependence of the gamma-relaxation time. We successfully applied the minimal model [Dyre and Olsen, Phys. Rev. Lett. 91, 155703 (2003)] to describe the entire temperature dependence of the gamma-relaxation time. The asymmetric double-well potential parameters obtained by Dyre and Olsen for the secondary relaxation of tripropylene glycol at ambient pressure were modified by fitting to the minimal model at lower temperatures. Moreover, we showed that the effect of the molecular weight of polypropylene glycol on the minimal model parameters is significantly larger than that of the high pressure. Such results can be explained by the smaller degree of hydrogen bonds formed by longer chain molecules of PPG at ambient pressure than that created by shorter chains of PPG at high pressure.

Journal Article↗
PubMed2005

Dielectric relaxation processes in water mixtures of tripropylene glycol.

Broadband dielectric measurements for anhydrous tripropylene glycol (3PG) and 96, 92, 84, 80, 74, 71, and 68 wt % 3PG-water mixtures are performed in the frequency range of 10(-2)-10(7) Hz and in the temperature range of 123-243 K. We examined the effect of adding water into anhydrous 3PG on relaxation dynamics. Apart from the two well-known relaxation processes, i.e., alpha and beta for anhydrous 3PG we observed new relaxation peak (beta') for all aqueous mixtures of 3PG. In addition we found the critical mole fraction of water x(w)=0.67 in which relaxation dynamics changes its behavior. According to the Sudo approach [S. Sudo et al., J. Non-Cryst. Solids 307-310, 356 (2002)], the behavior of relaxation processes was interpreted assuming the existence of three kinds of cooperative domains (CDs): containing only 3PG molecules, including only water molecules, and including both 3PG and water molecules, which molecules of each kind CD are bound by hydrogen bonds.

Absorption↗
PubMed2005

Computer simulation of the linear and nonlinear optical susceptibilities of p-nitroaniline in cyclohexane, 1,4-dioxane, and tetrahydrofuran in quadrupolar approximation. I. Molecular polarizabilities and hyperpolarizabilities.

This is the first part of a study of the local field effects on (non)linear optical susceptibilities of solutions of para-nitroaniline (pNA) in three different solvents, cyclohexane (CH), 1,4-dioxane (DI), and tetrahydrofuran (THF), using a discrete molecular representation of the condensed phase. To account for dipolar and quadrupolar effects, the latter of which are especially important for DI solution, all the electric properties necessary to compute the local fields and local field gradients in quadrupolar approximation as well as the dipolar hyperpolarizabilities for the four molecules are computed, including frequency dispersion and vibrational contributions to the dipolar properties. The convergence of the perturbation treatment for the pure vibrational (PV) contributions is examined by comparison of the values obtained at the lowest order with those of partially computed second order in mechanical and electrical anharmonicity. For pNA, for which previous computations of the hyperpolarizabilities have generally found poor agreement with experimental results, a thorough investigation of the effects of solvent-induced geometry changes, dynamic and static correlation, frequency dispersion, and classical thermal averaging over the torsional modes of the substituent groups and the inversion mode of the amino group on the dipolar properties is carried out. Computations using self-consistent continuum reaction field models show that the amino group is substantially less pyramidalized in polar solvents than in the gas phase. With all the effects taken into account, reasonable agreement with the experimental electric-field induced second harmonic generation (EFISH) result on pNA vapor of Kaatz, Donley, and Shelton is obtained.

Aniline Compounds↗
PubMed2001

Visual evoked potentials in patients with psoriasis vulgaris.

PURPOSE: The aim of this study is an estimation of the visual evoked potentials (VEP) in patients with psoriasis vulgaris. The role of the nervous system was pointed out in the pathogenesis of psoriasis. Also epidemiologic research confirms that patients with psoriasis are at increased risk of MS development. MATERIALS AND METHODS: A group of 30 psoriatic males aged between 18 and 54 was examined. The results were compared with those obtained from a group of 30 healthy age-matched males and they were correlated with the psoriasis area and severity index (PASI), the skin surface area involved, duration of the disease and duration of the last relapse. In neurological and ophthalmological examinations no pathological symptoms were detected in either group. The VEP examination was executed using pattern reversal (pr) and pattern flash (pf) stimulation. RESULTS: Using pf stimulation, in the group of patients with psoriasis vulgaris, a statistically significant elongation in the latency of P-100 and reduction of response amplitude, not related to the PASI, nor the skin surface area involved, nor duration of the last relapse, were observed. CONCLUSIONS: The results of the study indicate subclinical damage of the visual pathway in patients with psoriasis vulgaris.

Adolescent↗
PubMed1999

A congenital defect of the pericardium.

Ten patients with congenital defects of the pericardium were treated in Departments of Cardiac Surgery, Silesian School of Medicine in Zabrze and Katowice between 1989 and 1998. There were eight children and two adults, eight males and two females. In each case the pericardial defect was discovered intraoperatively during surgery for congenital heart defect. There were no cases with clinical symptoms that could be clearly related to the defect of the pericardial sac. In the case of a child with a complete absence of the left pericardial wall the heart was significantly rotated contrary to the defect. The final outcome of the congenital heart defect surgery was satisfactory in each case. An abbreviated historical review of the diagnosis and treatment of the pericardial defects is presented with special attention placed on therapeutic management. Surgical correction of pericardial defects is concluded to be justified in patients with clinical symptoms. In most cases pericardial defects are discovered intraoperatively, but when they are large the said defects do not require any treatment.

Adult↗
PubMed1999

[Cotinine--the biomarker of exposure to tobacco smoke].

Long-term exposure to tobacco smoke is conducive to increased morbidity rate of respiratory, alimentary and circulatory diseases. The biochemical and immunochemical studies permitted to assess the basic pathways of nicotine change in mammal organisms. The measurement of cotinine in the system fluids is a specific marker of the intensiveness of smoking, of the exposure connected with active and passive smoking and it can also be of use in nicotine therapy monitoring during the cessation of smoking.

Biomarkers↗
PubMed1999

[Past and present at the Polish Medical School in Edinburgh].

The article describes the history of the Polish Medical School at the University of Edinburgh, the world-wide unprecedented enterprise. Profiles of some distinguished Polish people or Scots of Polish descents associated with the Polish Medical School are presented.

History, 16th Century↗
PubMed1997

[Peritoneum as a dialysis membrane. II. Pathology].

Peritoneal dialysis is an established method of treatment of chronic renal failure. In that paper morphological and functional changes of peritoneum due to the process of long-term dialysis are presented. Morphological changes are observed in mesothelial cells, intercellular junctions, interstitial tissue and blood vessels. Moreover morphological changes in typical complications of chronic peritoneal dialysis, e. g. peritonitis, eosinophilic peritonitis, and sclerosing encapsulating peritonitis are described. Mechanisms of functional disorders during chronic peritoneal dialysis, involving the decreased permeability of the peritoneum, the increased permeability of the peritoneum and the enhanced lymphatic drainage are discussed. The article is the second of two parts presenting physiology and pathology of peritoneum as dialysis membrane.

Biocompatible Materials↗
PubMed1996

[Peritoneum as a dialysis membrane. I. Physiology].

The interest in structure and function of peritoneum increased when it turned out that it may be used as biologic dialysis membrane. The structure of peritoneum is of significant value in the course of peritoneal dialysis. The role of the mesothelium, the interstitium, blood and lymphatic capillaries, major constituents of peritoneum, have been deeply studied. Moreover, it is well known that process of dialysis influence the structure and function of different peritoneal elements. Having more date about physiological structure of these elements, and making conditions of peritoneal dialysis more physiologic might be crucial factors to reduce the amount of complications, and increase the usefulness of this method of treatment. This article is the first of two parts and discusses the peritoneal structure in physiologic conditions and in conditions of peritoneal dialysis.

Epithelium↗
PubMed1995

[The influence of nasopharyngeal obstruction on gasometric parameters in children].

The examinations were performed before and one month after adenoidectomy Comparison of the obtained results did not show significant changes in gasometric results due to operation. No correlation also was shown between the weight of the adenoid and changes in gasometric parameters after operation. In all children the improvement in clinical stage after operation was observed. Based on obtained results it seems that about nasopharyngeal obstruction in children with enlarged adenoid decides not its weight (size) only but the ratio between its size and nasopharyngeal capacity.

Adenoids↗
PubMed1995

[Evaluation of granulocyte (PMNL) function in patients with chronic inflammation of the middle ear and palatine tonsils].

The evaluation of granulocytes function (PMN) in patients with chronic inflammation of middle ear and palatine tonsils. There were 39 people examined and divided into: 28 patients with chronic inflammation of middle ear and palatine tonsil, 11 healthy persons. The function of granulocytes in patients with chronic inflammation of middle ear and palatine tonsil were changed more in comparison with the healthy people.

Adult↗
PubMed1995

[The influence of phleum pratense and secale cercale allergens on selected functions of PMNL granulocytes].

The evaluation of granulocytes function (PMNL) at patients with pollinosis. There were 59 people examined and divided into: 30 patients with pollinosis, 29 healthy people. There were evaluated: absorption of isotope (phagocytic index) in our modification migration in vivo and the bacteriotoxic index. The function of granulocytes (postpreincubation) of allergens Phlenum pratens and Secale cercale in patients with pollinosis were changed more in comparison with the healthy people.

Adult↗
PubMed1995

[The evaluation of granulocyte (PMNL) function of patients with chronic hypertrophy of larynx and paranasal sinuses].

The evaluation of granulocytes function (PMNL) at patients with chronic hypertrophy of larynx and paranasal sinuses. There were 40 people examined and divided into: 10 patients with hypertrophy of larynx, 13 patients with hypertrophy of paranasal sinuses and 17 healthy people. There were evaluated: emission of chemiluminescence (CL), absorption of isotope (phagocytic index) in our modification migration in vivo and in vitro and the bacteriotoxic index. The function of granulocytes in patients with hypertrophy of larynx and paranasal sinuses were changed more in comparison with the healthy people.

Adult↗
PubMed1992

[A case of direct right pulmonary artery-left atrium fistula].

An unusual case of cyanotic heart disease in a 20-year-old male has been presented. Cyanosis was due to right to left shunt through direct right pulmonary artery--left atrium fistula. After successful operative ligation of the fistula, the patient got rid of cyanosis and is doing well.

Abnormalities, Multiple↗
PubMed1992

[Anatomical correction of transposition of the great arteries in 7 newborn infants].

In the presented article, the course and results of anatomical correction of transposition of great arteries (TGA) in 7 neonates (2 females and 5 males) with mean body mass of 3250 g and 2 to 5 days old (mean 3 days) are reviewed. Surgery was performed in moderate hypothermia. St. Thomas cold cardioplegia was used. Mean aortic clamping time was 70 min (55-115), and the time of extracorporeal circulation was 165 min (117-210). Low cardiac output in all patients in the postoperative period required prolonged mechanical ventilation and positive inotropic drugs. Out of 7 patients operated, two died (29%). The cause of death in both cases was myocardial ischemia of right ventricle. The other 5 patients were discharged after healing of operational wound. In the control echocardiographic examination performed 3 to 12 months postoperatively, apart from one case of moderate pulmonary artery stenosis, no other haemodynamically significant complications were noted.

Coronary Vessel Anomalies↗