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Vaporization
Kinds of Vaporization Selected AbstractsPyogenic Granuloma: Satellitosis after Carbon Dioxide Laser Vaporization Resolved with an Intense Pulsed Light SystemDERMATOLOGIC SURGERY, Issue 1 2007SABELA PARADELA MD First page of article [source] Angiokeratoma Circumscriptum Naeviforme: Successful Treatment with Carbon-Dioxide Laser VaporizationDERMATOLOGIC SURGERY, Issue 2 2005Jesús del Pozo MD Background Angiokeratoma circumscriptum naeviforme (ACN) is an unusual type of localized angiokeratoma that occurs more frequently in females and is usually located on the buttocks or thighs, showing a unilateral distribution. ACN usually causes large lesions, which may require laser ablation because they often are too extensive to perform surgical excision. Carbon-dioxide laser is a known alternative for treating angiokeratomas. Objective Report of two cases of ACN treated with carbon-dioxide laser vaporization. Patients and methods A 28-year-old woman with a hyperkeratotic, violaceus plaque on her left buttock and a 24-year-old woman with a similar lesion on her right buttock were treated with a carbon-dioxide laser. Two laser passes were performed on each lesion within a single session. Results A successful cosmetic aspect of treated areas was obtained, with minimal pigmentary or textural changes. After a 2-year follow-up in the first patient and a 6-month follow-up in the second patient, no recurrence of the lesions was observed. Conclusions Our results, obtaining relevant cosmetic improvement after a few sessions of treatment, with low morbidity and minimal secondary effects, suggest that continuous-wave carbon-dioxide laser vaporization is a safe and effective treatment for ACN. JESÚS DEL POZO, MD, AND EDUARDO FONSECA, MD, HAVE INDICATED NO SIGNIFICANT INTEREST WITH COMMERCIAL SUPPORTERS. [source] Port-Wine Stain Nodules in the Adult: Report of 20 Cases Treated by CO2 Laser VaporizationDERMATOLOGIC SURGERY, Issue 8 2001Jesús Del Pozo MD Background. Port-wine stain (PWS) is a congenital vascular malformation of the superficial dermal vessels. These vessels become progressively ectatic, with development of nodular and hypertrophic areas on the surface of the lesions. Objective. To determine the efficacy of CO2 laser vaporization in the treatment of nodules in PWS. Methods. Twenty adult patients with PWS who developed nodules and hypertrophy on the surface of the lesions were treated by CO2 laser vaporization. Only one pass was performed to each area of the lesions, using a continuous and defocused mode, with a power density of 10 W/cm2. When the treated lesion was very large, several sessions of treatment were necessary to vaporize its entire surface. Photographic controls were performed before and after treatment. Results. The nodules and hypertrophy were removed and the smooth surface of the lesions was reestablished. The color, usually violaceous, was transformed in a slight erythema. Conclusion. CO2 laser is a good method for treatment of nodules and hypertrophy in PWS. With adequate precautions, excellent cosmetic results can be obtained. Other more-specific laser systems may be successively used to treat the remaining erythema. [source] Early Results of Photoselective Vaporization of the Prostate in Medical Control-failed PatientsLUTS, Issue 2 2009Shen Kuang CHANG Objectives: We present here our early results and learning curve for photoselective vaporization of the prostate (PVP) performed by an experienced urologist and we provide an analysis of the morbidity and early functional outcomes. Methods: Forty-four patients were selected, from May 2006 to January 2009, who had benign prostate hyperplasia (BPH) accompanied by lower urinary tract symptoms (LUTS). After undergoing PVP for BPH at our hospital, the patients were followed up for approximately 2 years. PVP was performed by the same experienced urologist using potassium-titanyl-phosphate (KTP) laser. Baseline characteristics, preoperative and perioperative data, and postoperative complications were evaluated. Regular outpatient department follow-up was conducted after patients were discharged from the hospital at 1, 4 and 12 weeks. Results: The mean age of the 44 patients was 71.6 years. The mean prostate volume was 47.52 mL. The mean PVP surgery time was 79.11 min. The mean urinary catheterization time was 23.41 h. Few complications arose after PVP, except that 47.7% of the patients developed pyuria after being discharged from hospital. The average hospital stay was 2.45 days. There were no significant differences in the efficiency of tissue vaporization among the patients. Conclusion: PVP for BPH has various advantages, including reducing postoperative complications. An experienced urologist can easily perform PVP. However, early results show no significant differences in the efficiency for the PVP technique. [source] High-temperature mass spectrometric study of the vaporization processes of V2O3 and vanadium-containing slagsRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 16 2010H. Wang A Knudsen effusion mass spectrometric method was used to study the vaporization processes and thermodynamic properties of pure V2O3 and 14 samples of vanadium-containing slags in the CaO-MgO-Al2O3 -SiO2 system in the temperature range 1875,2625,K. The system was calibrated using gold in the liquid state as the standard. Vaporization was carried out from double tungsten effusion cells. First it was shown that, in vapor over V2O3 and the vanadium-containing slags in the temperature range 1875,2100,K, the following vapor species were present: VO2, VO, O, WO3 and WO2, with the latter two species being formed as a result of interaction with the tungsten crucibles. The temperature dependencies of the partial pressures of these vapor species were obtained over V2O3 and the slags. The ion current comparison method was used for the determination of the V2O3 activities in slags as a function of temperature with solid V2O3 as a reference state. The V2O3 activity coefficients in the slags under investigation indicated positive deviations from ideality at 1900,K and a tendency to ideal behavior at 2100,K. It was shown that the V2O3 activity as a function of the slag basicity decreased at 1900,K and 2000,K and was practically constant in the slag melts at 2100,K. The results are expected to be valuable in the optimization of slag composition in high-alloy steelmaking processes as well as for their environmental implications. Copyright © 2010 John Wiley & Sons, Ltd. [source] The Isolable Matryoshka Nesting Doll Icosahedral Cluster [As@Ni12@As20]3- as a "Superatom": Analogy with the Jellium Cluster Al13 - Generated in the Gas Phase by Laser Vaporization.CHEMINFORM, Issue 2 2007R. Bruce King Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source] Angiokeratoma Circumscriptum Naeviforme: Successful Treatment with Carbon-Dioxide Laser VaporizationDERMATOLOGIC SURGERY, Issue 2 2005Jesús del Pozo MD Background Angiokeratoma circumscriptum naeviforme (ACN) is an unusual type of localized angiokeratoma that occurs more frequently in females and is usually located on the buttocks or thighs, showing a unilateral distribution. ACN usually causes large lesions, which may require laser ablation because they often are too extensive to perform surgical excision. Carbon-dioxide laser is a known alternative for treating angiokeratomas. Objective Report of two cases of ACN treated with carbon-dioxide laser vaporization. Patients and methods A 28-year-old woman with a hyperkeratotic, violaceus plaque on her left buttock and a 24-year-old woman with a similar lesion on her right buttock were treated with a carbon-dioxide laser. Two laser passes were performed on each lesion within a single session. Results A successful cosmetic aspect of treated areas was obtained, with minimal pigmentary or textural changes. After a 2-year follow-up in the first patient and a 6-month follow-up in the second patient, no recurrence of the lesions was observed. Conclusions Our results, obtaining relevant cosmetic improvement after a few sessions of treatment, with low morbidity and minimal secondary effects, suggest that continuous-wave carbon-dioxide laser vaporization is a safe and effective treatment for ACN. JESÚS DEL POZO, MD, AND EDUARDO FONSECA, MD, HAVE INDICATED NO SIGNIFICANT INTEREST WITH COMMERCIAL SUPPORTERS. [source] CO2 Laser Treatment of Epidermal Nevi: Long-Term SuccessDERMATOLOGIC SURGERY, Issue 7 2002Sarah Boyce MD background. Epidermal nevi have been notoriously difficult to treat due to their large size and often conspicuous location. Variable results have been obtained with different laser treatments, and scarring and/or incomplete removal is typical after excisional or other destructive modalities. objective. To outline the successful use of a short-pulsed CO2 laser in the long-term eradication of epidermal nevi in three patients. methods. Three females (ages 15,19) presented with extensive grouped verrucous papules and plaques on the face, trunk, and extremities. A pulsed CO2 laser was used to vaporize the lesions using a 500 mJ pulse energy, 3 mm spotsize, and 7 watts of power. results. All lesions healed without incident. No lesional recurrence was observed 10 to 13 months after treatment except in one small area on the ankle in one patient. conclusions. Carbon dioxide laser vaporization of epidermal nevi provides good clinical effect and offers unique advantages for the treatment of these lesions, including effective intraoperative hemostasis with excellent lesional visualization. It is also possible to treat widespread areas in one laser treatment session. While the results of this series clearly show the benefit of CO2 laser treatment, epidermal nevi may not always respond so favorably, due in part to the variability in their depths of involvement. [source] Port-Wine Stain Nodules in the Adult: Report of 20 Cases Treated by CO2 Laser VaporizationDERMATOLOGIC SURGERY, Issue 8 2001Jesús Del Pozo MD Background. Port-wine stain (PWS) is a congenital vascular malformation of the superficial dermal vessels. These vessels become progressively ectatic, with development of nodular and hypertrophic areas on the surface of the lesions. Objective. To determine the efficacy of CO2 laser vaporization in the treatment of nodules in PWS. Methods. Twenty adult patients with PWS who developed nodules and hypertrophy on the surface of the lesions were treated by CO2 laser vaporization. Only one pass was performed to each area of the lesions, using a continuous and defocused mode, with a power density of 10 W/cm2. When the treated lesion was very large, several sessions of treatment were necessary to vaporize its entire surface. Photographic controls were performed before and after treatment. Results. The nodules and hypertrophy were removed and the smooth surface of the lesions was reestablished. The color, usually violaceous, was transformed in a slight erythema. Conclusion. CO2 laser is a good method for treatment of nodules and hypertrophy in PWS. With adequate precautions, excellent cosmetic results can be obtained. Other more-specific laser systems may be successively used to treat the remaining erythema. [source] Cavitation versus Degassing: In Vitro Study of the Microbubble Phenomenon Observed During Echocardiography in Patients with Mechanical Prosthetic Cardiac ValvesECHOCARDIOGRAPHY, Issue 7 2002Grégoire Girod M.D. Background: With the advent of second harmonic imaging in echocardiography, microbubbles have been observed during opening and closure of mechanical prosthetic valves. The single phenomenon of cavitation, an extremely short event described in the literature, cannot explain the persistence of microbubbles during several hundred milliseconds. Therefore, in vitro we reproduced two distinct phenomena created by a local depression occurring during the closure and/or opening of prosthetic valves: Cavitation and degassing. Methods: We used a water circuit system enriched with CO2 that passes through a Venturi tube in order to create variable pressure gradients. Three types of observations were performed: (1) the dimensions of the bubbles as a function of pressure, (2) calibration of the echocardiograph, and (3) comparison and illustrations of the difference between bubble formation by cavitation (vaporization) and degassing (liberation of CO2). Results: According to the different pressures exerted, the dimensions of the bubbles only vary by several microns, not measurable in practice. Second, the calibration of the echocardiograph reveals that the dimensions of the bubbles measured by ultrasound are greater by a factor of 1.75. Finally, the observed cavitation is a short phenomenon (several milliseconds) and happens under a great local pressure gradient. The degassing produces microbubbles lasting up to as long as > 1 second under much lower pressure. Conclusion: This in vitro study suggests that microbubbles observed during several hundred milliseconds after the opening of prosthetic cardiac valves are the result of degassing of CO2 in blood rather than a cavitation phenomenon as suggested in the literature. [source] Determination of physicochemical properties of tetrabromobisphenol AENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 12 2008Hidetoshi Kuramochi Abstract Aqueous solubility (Sw), 1-octanol/water partition coefficient (KOW), and vapor pressure of the nonionic form of 2,2,,6,6,-tetrabromo-4,4,-isopropylidenediphenol (tetrabromobisphenol A or TBBP-A) were measured. From this, enthalpies of solution and vaporization were estimated. Furthermore, enthalpy of fusion and melting point were measured to estimate subcooled liquid vapor pressure, the infinite dilution activity coefficient, and Henry's law constant. Since TBBP-A is expected to exit in both ionic and nonionic forms at near neutral pH, pH effects on physicochemical properties were also examined. Because of the ionization of TBBP-A, Sw increased by five orders of magnitude, while KOW decreased by eight orders of magnitude. Furthermore, an analytical model based on mass balance and dissociation of TBBP-A was applied to represent the pH dependence. [source] Dichlorodiphenyltrichloroethane in the aquatic ecosystem of the Okavango Delta, Botswana, South AfricaENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 1 2003Bontle Mbongwe Abstract Concentrations of DDT and its metabolites were measured in water, plants, invertebrates, and fish from lagoons in the Okavango Delta, Botswana (Africa), where DDT has been used for approximately 50 years. The sampling area was sectioned to distinguish spraying for malaria and for African sleeping sickness. Average concentrations of total DDT (sum of DDT and its metabolites) in the Okavango ranged from 0.009 ng/L in water to 18.76 ng/g wet weight in fish. These levels are approximately 1% of those found in piscivorous fish from temperate North America. The dichlorodiphenyl ethylene (DDE) metabolite was the most abundant fraction of total DDT. Although total DDT concentrations were higher in areas treated for malaria than areas treated for sleeping sickness, these concentrations were likely driven by factors other than the historic application of the pesticide. Equilibration with air concentrations is the most likely explanation for these levels. Since the mean annual temperature exceeds the temperature of vaporization of DDT, this research points to the need for reliable transport models. Our results showed that total DDT concentration in fish was best explained by lipid content of the fish and trophic position inferred by ,15N, regardless of DDT application history in those areas. The reservoir above Gaborone Dam, an area downstream of the Okavango but where DDT had not been used, was sampled to compare total DDT levels to the treated areas. The two species (a herbivorous threespot talapia and the omnivorous sharptooth catfish) from Gaborone had levels higher than those found in the Okavango Delta, but these differences can again be explained using trophic position inferred by ,15N rather than by fish size or location. [source] Heteroleptic Guanidinate- and Amidinate-Based Complexes of Hafnium as New Precursors for MOCVD of HfO2EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 11 2010Ke Xu Abstract The synthesis and characterization of four new heteroleptic complexes [Hf{,2 -(iPrN)2CNMe2}2Cl2] (1), [Hf{,2 -(iPrN)2CNMe2}2Me2] (2), [Hf{,2 -(iPrN)2CMe}2Cl2] (3), and [Hf{,2 -(iPrN)2CMe}2Me2] (4) are reported. All the complexes were characterized by spectroscopic methods, while compounds 1,3 were further examined by single-crystal X-ray diffraction, revealing that the complexes are monomers with the hafnium center in a distorted octahedral geometry. The thermal properties of the chlorine-free complexes (2, 4) were examined to determine their suitability for metalorganic chemical vapor deposition (MOCVD) applications, and compound 2 showed good volatility and thermal stability. On the basis of these results, compound 2 was selected for MOCVD of HfO2 with oxygen as oxidant. Depositions were carried out on Si(100) substrates in the temperature range 300,700 °C. The as-deposited HfO2 films crystallized in the monoclinic phase at temperatures above 500 °C, and the composition analysis determined by Rutherford back-scattering (RBS) and X-ray photoelectron spectroscopy (XPS) revealed that the films were stoichiometric and free of carbon. Thus, alkylguanidinatohafnium complex 2 is a promising precursor for growing HfO2 films in a wide temperature range with the desired stoichiometry, because of its adequate volatility, sufficient temperature window between vaporization and decomposition, as well as its ability to decompose cleanly in the presence of oxygen. [source] The Fate of Lead in MSWI-Fly Ash During Heat Treatment: An X-Ray Absorption Spectroscopy Study,ADVANCED ENGINEERING MATERIALS, Issue 6 2009Rudolf Paul Wilhelm Jozef Struis The study focuses on the potential of removing toxifying Pb from a certified, multi-element fly ash (BCR176) by thermal treatment between 300 and 950,°C under different carrier gas compositions (Ar or Ar,+,O2). The treatment was studied by in situ monitoring the evaporation rate of Pb, C, S, Na, and K during heating and by synchrotron X-ray absorption spectroscopy of selected samples collected during vaporization at the Pb L3 -edge. [source] On blends R32/R134a and R32/R125: Thermodynamic and heat transfer aspectsINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 9 2001A. Stegou-SagiaArticle first published online: 4 JUN 200 Abstract In this paper the author develops an algorithm on the basis of heat and thermodynamics theory, to predict data for film condensation on horizontal integral,fin tubes for R32/R134a and R32/R125 mixtures in 25/75, 50/50 per cent compositions by mass correspondingly. Emphasis is focused on the presentation of thermophysical properties of the blends involved in the process considered, i.e. liquid density, viscosity, surface tension, thermal conductivity and latent heat of vaporization. The main point of this work is to define with computational techniques the blend with the most favourable composition, as an environmentally acceptable solution for R22 replacement in some shell-side condensers. Copyright © 2001 John Wiley & Sons, Ltd. [source] A computationally inexpensive modification of the point dipole electrostatic polarization model for molecular simulationsJOURNAL OF COMPUTATIONAL CHEMISTRY, Issue 3 2003George A. Kaminski Abstract We present an approximation, which allows reduction of computational resources needed to explicitly incorporate electrostatic polarization into molecular simulations utilizing empirical force fields. The proposed method is employed to compute three-body energies of molecular complexes with dipolar electrostatic probes, gas-phase dimerization energies, and pure liquid properties for five systems that are important in biophysical and organic simulations,water, methanol, methylamine, methanethiol, and acetamide. In all the cases, the three-body energies agreed with high level ab initio data within 0.07 kcal/mol, dimerization energies,within 0.43 kcal/mol (except for the special case of the CH3SH), and computed heats of vaporization and densities differed from the experimental results by less than 2%. Moreover, because the presented method allows a significant reduction in computational cost, we were able to carry out the liquid-state calculations with Monte Carlo technique. Comparison with the full-scale point dipole method showed that the computational time was reduced by 3.5 to more than 20 times, depending on the system in hand and on the desired level of the full-scale model accuracy, while the difference in energetic results between the full-scale and the presented approximate model was not great in the most cases. Comparison with the nonpolarizable OPLS-AA force field for all the substances involved and with the polarizable POL3 and q90 models for water and methanol, respectively, demonstrates that the presented technique allows reduction of computational cost with no sacrifice of accuracy. We hope that the proposed method will be of benefit to research employing molecular modeling technique in the biophysical and physical organic chemistry areas. © 2003 Wiley Periodicals, Inc. J Comput Chem 24: 267,276, 2003 [source] MOISTURE SORPTION ISOTHERM, PROPERTIES OF SORBED WATER AND HEAT OF SORPTION OF SANDESH, AN INDIAN MILK PRODUCTJOURNAL OF FOOD PROCESSING AND PRESERVATION, Issue 1 2010J.K. SAHU ABSTRACT Moisture sorption isotherm of sandesh, one of the most popular milk products in India, was determined in terms of its moisture adsorption isotherms by gravimetrical method at 20 and 30C using various saturated salt solutions in the range of 11.2 to 97.2%. The isotherms obtained were of sigmoid shape and of the Brunauer,Emmett,Teller type. Out of three sorption models fitted to the experimental data, Caurie's model was found superior in interpreting the moisture adsorption characteristics of sandesh. The monolayer moisture content as calculated from the Caurie's model at 20 and 30C were 5.89% (dry basis [d.b.]) and 5.21% (d.b.), respectively. The values of isosteric heat of sorption as calculated from Clausius,Clapeyron equation was found to increase with decreasing moisture content at lower moisture content and approached the value of heat of vaporization of free water above 17.25% (d.b.). PRACTICAL APPLICATIONS The present paper describes basically the storage stability of sandesh. The sandesh is a heat,acid coagulated product of milk in Indian subcontinent and forms the part and parcel of social life, ceremonies and festivals. It has an excellent market potential and higher profit margin compared with other milk products like table butter, cheese and milk powder. Although Indian dairy industry has made rapid strides in the last few decades, there is no proper packaging system, developed so far, for storage of sandesh. Keeping pace with the growing consumers' demand for fresh, convenient and microbiologically free foods, design of proper packaging system is the need of the hour. The data presented in the paper will be very much essential for the researchers and research and development institutions for proper designing of packaging system for sandesh. [source] Mechanism of foaming on polymer-paperboard compositesAICHE JOURNAL, Issue 2 2008S. Kiran Annapragada Abstract Foamed paperboard is a composite material with applications in the consumer products industry. The composite is comprised of paperboard sandwiched between two layers of polymers. One layer foams upon heating while the other acts as a barrier layer. Foaming is caused by the vaporization of the small amount of moisture present in the board and the resulting increase in pressure. The mechanism of foaming was investigated with a combination of high-speed photography, scanning electron microscopy, and infrared thermography using foamed paperboard of different compositions prepared both in the laboratory and on a commercial machine. The surface uniformity of the paper was found to be the overriding paper-related property controlling bubble formation. © 2007 American Institute of Chemical Engineers AIChE J, 2008 [source] Thermal machines based on surface energy of wetting: Thermodynamic analysisAICHE JOURNAL, Issue 3 2003A. Laouir This work proposes an original thermodynamic-energetic analysis of the feasibility and ideal performance of thermal machines based on the wetting phenomenon proposed by V. A. Eroshenko. The extension or contraction of a liquid film is taken as a "tutorial" example to introduce the basic thermodynamic relations of this 2-D transformation. It implies both mechanical and thermal effects, and this coupling allows conversion of heat to work (thermal engine) or conversely to pump heat (refrigeration/heat pump effect). A similar approach is then developed for the interface between a liquid and a highly microporous solid, having a large internal surface area. The thermodynamic behavior of this interface involves as state variables the surface tension of the liquid, the contact angle, and their dependence on temperature. Depending on the relative magnitude and sign of these quantities, and, therefore, on the working couple and the temperature range, a variety of machine cycles are feasible, or excluded, and a method is proposed for a comprehensive inventory. Order-of-magnitude calculations of the energy densities are presented based on the existing experimental data for several systems involving water as the fluid. The tentative conclusions are that the energy densities are very small on a mass basis compared to conventional systems based on vaporization, but the contrary is true on a volume basis because the phase transformation (extension of the surface) occurs in a condensed state. There may, therefore, be some niches for thermal machines of this type, but they remain to be identified and validated. [source] Al3BC3 Powder: Processing and Synthetic MechanismJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 12 2009Sea-Hoon Lee The processing parameters for the synthesis of Al3BC3 powder were optimized, and the synthetic mechanism was investigated. The mechanical mixing of the raw powders promoted the formation of secondary phases due to mechanical alloying effect and contamination. Nearly X-ray pure Al3BC3 powder was obtained after the calcination of the raw powder mixture at 1800°C for 2 h in Ar by suppressing the vaporization of aluminum. During calcination, Al4C3 layer was formed at the surface of aluminum powder by the reaction with carbon, which maintained the morphology of the aluminum powder above its melting temperature. The nucleation and growth of Al3BC3 within aluminum melt began to occur at 1000°C, and became the main synthetic mechanism of Al3BC3 at 1100°C. The Al3BC3 particles synthesized at 1100°C were porous and were composed of fine hexagonal crystals. The main synthetic mechanism of A3BC3 changed into solid,solid reaction above 1100°C, and a gas,solid reaction promoted the densification of the porous Al3BC3 powder above 1340°C. [source] Retention of aroma compounds: an interlaboratory study on the effect of the composition of food matrices on thermodynamic parameters in comparison with waterJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 8 2010Mirela Kopjar Abstract BACKGROUND: Partition coefficients give an indication of the retention of aroma compounds by the food matrix. Data in the literature are obtained by various methods, under various conditions and expressed in various units, and it is thus difficult to compare the results. The aim of the present study was first to obtain gas/water and gas/matrix partition coefficients of selected aroma compounds, at different temperatures, in order to calculate thermodynamic parameters and second to compare the retention of these aroma compounds in different food matrices. RESULTS: Yogurts containing lipids and proteins induced a higher retention of aroma compounds than model gel matrices. The observed effects strongly depend on hydrophobicity of aroma compounds showing a retention for ethyl hexanoate and a salting out effect for ethyl acetate. A small but noticeable decrease in enthalpy of affinity is observed for ethyl butyrate and ethyl hexanoate between water and food matrices, suggesting that the energy needed for the volatilization is lower in matrices than in water. CONCLUSION: The composition and complexity of a food matrix influence gas/matrix partition coefficients or aroma compounds in function of their hydrophobicity and to a lower extent enthalpy of vaporization. Copyright © 2010 Society of Chemical Industry [source] Photothermal and accompanied phenomena of selective nanophotothermolysis with gold nanoparticles and laser pulsesLASER PHYSICS LETTERS, Issue 11 2008V.K. Pustovalov Abstract In medical applications of laser and nanotechnology to diagnosis and treat cancer or microorganisms, understanding of lased-induced photothermal (PT) and accompanied phenomena around nanoparticles are crucial for optimization and bringing this promising technology to bedside. We analyzed the main Ptbased effects in and around gold nanoparticles under action of short (nano-, pico-, and femtosecond) laser pulses with focus on photoacoustic effects due to the thermal expansion of nanoparticles and liquid around them, thermal protein denaturation, explosive liquid vaporization, melting and evaporation of nanoparticle, optical breakdown initiated by nanoparticles and accompanied to shock waves and explosion (fragmentation) of gold nanoparticles. Characteristic parameters for these processes such as the temperature and pressures levels, and laser intensity thresholds among others are summarized to provide basis for comparison of different mechanisms of selective nanophotothermolysis and diagnostics of different targets (e.g., cancer cells, bacteria, viruses). (© 2008 by Astro Ltd., Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA) [source] Mechanistic comparison of blood undergoing laser photocoagulation at 532 and 1,064 nmLASERS IN SURGERY AND MEDICINE, Issue 2 2005John F. Black PhD Abstract Background and Objectives We seek to compare and contrast the mechanisms of blood photocoagulation under 532 and 1,064 nm laser irradiation in vitro in order to better understand the in vivo observations. We also seek to validate a finite element model (FEM) developed to study the thermodynamics of coagulation. Study Design/Materials and Methods We study the photocoagulation of whole blood in vitro at 532 and 1,064 nm using time-domain spectroscopic and optical coherence tomography (OCT)-based imaging techniques. We model the coagulation using an FEM program that includes the latent heat of vaporization (LHV) of water, consideration of the pulse shape of the laser, and the bathochromic shift in the hemoglobin absorption spectrum. Results We find significant similarities in the spectroscopic, chemical, and structural changes occurring in hemoglobin and in the blood matrix during photocoagulation despite the very large difference in the absorption coefficients. The more uniform temperature profile developed by the deeper-penetrating 1,064 nm laser allows us to resolve the structural phase transition in the red blood cells (going from biconcave disc to spherocyte) and the chemical transition creating met-hemoglobin. We find that the RBC morphology transition happens first, and that the met-Hb transition happens at a much higher temperature (,>,90°C) than is found in slow bath heating. The FEM analysis with the LHV constraint and bathochromic shift predicts accurately the imaging results in both cases, and can be used to show that at 1,064 nm there is the potential for a runaway increase in absorption during the laser pulse. Conclusions Photothermally mediated processes dominate the in vitro coagulation dynamics in both regimes despite the difference in absorption coefficients. There is a significant risk under 1,064 nm irradiation of vascular lesions in vivo that the dynamic optical properties of blood will cause runaway absorption and heating. This may in turn explain some recent results at this wavelength where full-thickness burns resulted from laser treatment. Lasers Surg. Med. 36:155,165, 2005. © 2005 Wiley-Liss, Inc. [source] Transurethral endoscopic treatment of upper urinary tract tumors using a holmium:YAG laserLASERS IN SURGERY AND MEDICINE, Issue 5 2003Kei Matsuoka MD Abstract Background and Objectives The feasibility of treating upper urinary tract tumors with a holmium:YAG (Ho:YAG) laser in transurethral endoscopy was examined. Study Design/Materials and Methods Thirty-three treatments were performed on 30 patients with renal pelvic and ureteral carcinomas. After vaporization and coagulation eliminated the tumors, the surrounding mucosa was fully coagulated. Postoperative follow-up consisted of urinary cytology once a month, cystoscopy every 3 months, excretory pyelography every 6 months, and uretero-pyeloscopy every 6,12 months. Results The recurrence rate after the first treatment was 86% in the imperative indication group. The tumor-free rate (median follow-up, 37 months) in the imperative indication group was 57%. In the elective indication group, those values were 20 and 95% (median follow-up, 33 months), respectively. Conclusions Transurethral endoscopic treatment of upper urinary tract tumors using Ho:YAG laser can be a useful method on limited cases identified into specific treatments groups combined with a strict follow-up. Lasers Surg. Med. 32:336,340, 2003. © 2003 Wiley-Liss, Inc. [source] Early Results of Photoselective Vaporization of the Prostate in Medical Control-failed PatientsLUTS, Issue 2 2009Shen Kuang CHANG Objectives: We present here our early results and learning curve for photoselective vaporization of the prostate (PVP) performed by an experienced urologist and we provide an analysis of the morbidity and early functional outcomes. Methods: Forty-four patients were selected, from May 2006 to January 2009, who had benign prostate hyperplasia (BPH) accompanied by lower urinary tract symptoms (LUTS). After undergoing PVP for BPH at our hospital, the patients were followed up for approximately 2 years. PVP was performed by the same experienced urologist using potassium-titanyl-phosphate (KTP) laser. Baseline characteristics, preoperative and perioperative data, and postoperative complications were evaluated. Regular outpatient department follow-up was conducted after patients were discharged from the hospital at 1, 4 and 12 weeks. Results: The mean age of the 44 patients was 71.6 years. The mean prostate volume was 47.52 mL. The mean PVP surgery time was 79.11 min. The mean urinary catheterization time was 23.41 h. Few complications arose after PVP, except that 47.7% of the patients developed pyuria after being discharged from hospital. The average hospital stay was 2.45 days. There were no significant differences in the efficiency of tissue vaporization among the patients. Conclusion: PVP for BPH has various advantages, including reducing postoperative complications. An experienced urologist can easily perform PVP. However, early results show no significant differences in the efficiency for the PVP technique. [source] Vapor-condensed phase processes in the early solar systemMETEORITICS & PLANETARY SCIENCE, Issue 1 2010Lawrence GROSSMAN Many refractory inclusions in CM2 chondrites contain a relatively SiO2 -poor assemblage (spinel, hibonite, grossite, perovskite, corundum) that represents a high-temperature stage of condensation, and some may be pristine condensates that escaped later melting. Compact Type A and Type B refractory inclusions, consisting of spinel, melilite, perovskite, Ca-rich clinopyroxene ± anorthite, in CV3 chondrites are more SiO2 -rich and equilibrated with the solar nebular gas at a slightly lower temperature. Textures of many of these objects indicate that they underwent melting after condensation, crystallizing into the same phase assemblage as their precursors. The Ti3+/Ti4+ ratio of their pyroxene indicates that this process occurred in a gas whose oxygen fugacity () was approximately 8.5 log units below that of the iron-wüstite buffer, making them the only objects in chondrites known to have formed in a system whose composition was close to that of the sun. Relative to CI chondrites, these inclusions are uniformly enriched in a group of elements (e.g., Ca, REE, Zr, Ta, Ir) that are chemically diverse except for their high condensation temperatures in a system of solar composition. The enrichment factor, 17.5, can be interpreted to mean that these objects represent either the first 5.7 wt% of the condensable matter to condense during nebular cooling or the residue after vaporization of 94.3% of a CI chondrite precursor. The Mg and Si isotopic compositions of Types A and B inclusions are mass-fractionated by up to 10 and 4 ,/amu, respectively. When interpreted in terms of Rayleigh fractionation during evaporation of Mg and Si from the inclusions while they were molten, the isotopic compositions imply that up to 60% of the Mg and up to 25% of the Si were evaporated, and that approximately 80% of the enrichment in refractory (CaO+Al2O3) relative to more volatile (MgO+SiO2) in the average inclusion is due to initial condensation and approximately 20% due to subsequent evaporation. The mineralogical composition, including the Ti3+/Ti4+ ratio of the pyroxene, in Inti, a particle sampled from Comet Wild 2 by the Stardust spacecraft, is nearly identical to that of a Type B inclusion, indicating that comets contain not only the lowest-temperature condensates in the form of ices but the highest-temperature condensates as well. The FeO/(FeO+MgO) ratios of olivine and pyroxene in the matrix and chondrules of carbonaceous and ordinary chondrites are too high to be made in a system of solar composition, requiring s only 1 or 2 log units below iron-wüstite, more than 105 times higher than that of a solar gas. Various ways have been devised to generate cosmic gases sufficiently oxidizing to stabilize significant FeO in olivine at temperatures above those where Fe-Mg interdiffusion in olivine ceases. One is by vertical settling of dust toward the nebular midplane, enriching a region in dust relative to gas. Because dust is enriched in oxygen compared to carbon and hydrogen relative to solar composition, a higher results from total vaporization of the region, but the factor by which theoretical models have so far enriched the dust is 10 times too low. Another is by transporting icy bodies from the outer part of the nebula into the hot, inner part where vaporization of water ice occurs. Not only does this method fail to make the needed by a factor of 30,1000 but it also ignores simultaneous evaporation of carbon-bearing ices that would make the even lower. [source] Evaluating planetesimal bow shocks as sites for chondrule formationMETEORITICS & PLANETARY SCIENCE, Issue 11 2004Fred J. CIESLA The formation of such shocks is modeled using a piecewise parabolic method (PPM) code under a variety of conditions. The results of this modeling are used as a guide to study chondrule formation in a one-dimensional, finite shock wave. This model considers a mixture of chondrule-sized particles and micron-sized dust and models the kinetic vaporization of the solids. We found that only planetesimals with a radius of ,1000 km and moving at least ,8 km/s with respect to the nebular gas can generate shocks that would allow chondrule-sized particles to have peak temperatures and cooling rates that are generally consistent with what has been inferred for chondrules. Planetesimals with smaller radii tend to produce lower peak temperatures and cooling rates that are too high. However, the peak temperatures of chondrules are only matched for low values of chondrule wavelength-averaged emissivity. Very slow cooling (<,100s of K/hr) can only be achieved if the nebular opacity is low, which may result after a significant amount of material has been accreted into objects that are chondrule-sized or larger, or if chondrules formed in regions of the nebula with small dust concentrations. Large shock waves of approximately the same scale as those formed by gravitational instabilities or tidal interactions between the nebula and a young Jupiter do not require this to match the inferred thermal histories of chondrules. [source] Laser,target interaction during high-power pulsed laser deposition of superconducting thin filmsPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 12 2007Ranran Fang Abstract We present a theoretical model to describe the high-power nanosecond pulsed laser ablation of multi-elemental oxide superconductors by considering both the vaporization effect and the plasma shielding effect. Using as an example a YBa2Cu3O7 target, the numerical solutions are obtained by solving the heat flow equations using a finite difference method. We obtain the time dependence of temperature, the transmitted intensity and the ablation rate of the target. The numerical results agree well with the experimental data and are much better than without considering the effects of vaporization and plasma shielding, which indicates that the two effects in high-power nanosecond laser ablation of superconductors must not be neglected. The present model will be helpful for the investigation of superconducting thin films prepared by pulsed laser deposition. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] AFM and SNOM characterization of ordinary chondrites: A contribution to solving the problem of asteroid reddeningPHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 8 2010Giuliano Pompeo Abstract Space weathering (SW) is an ensemble of processes that act on a body exposed to the space environment. Typically, the exposure to SW results in the accumulation, at the surface, of nanoparticles, that are thought to be produced through a vaporization and subsequent cooling of the metallo-silicaceous components exposed to the space environment. The presence of such nanoparticles is responsible for the so-called reddening of the asteroids' reflectance spectra (i.e., the increase in Vis,NIR reflectance with increase in wavelength) observed by remote-sensing measurements. To investigate the mechanism of formation of these nanoparticles, we have employed atomic force microscopy (AFM) and scanning near-field optical microscopy (SNOM) to morphologically and optically characterize ordinary chondrites (OC), the most abundant class of meteorites collected on Earth and whose parent bodies are the S-type asteroids. The AFM study reveals the occurrence of a diffuse nanophase (martensite) in the meteorite's metal inclusions. Since the same areas show a reddening of the reflectivity spectra, this suggests that such spectral modification is based on a shock-induced phase transformation of the metal components of the extraterrestrial body. To gain more insight into this nanophase and on its role in the SW of the asteroids, an optical characterization by SNOM has been performed on OCs. In this work we exploited the peculiarity of this technique to search for a correlation between the topography on the nanoscale and the spectral characteristics, at different wavelengths in the red-NIR range, of the observed nanophase. Indeed, a high-resolution mapping of the optical properties of the meteorite provides an interesting method to discriminate between martensite-based and Fe-silicaceous nanoparticles. [source] In situ time-resolved measurements of carbon nanotube and nanohorn growthPHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 11 2007D. B. Geohegan Abstract Growth mechanisms of carbon nanotubes are investigated and compared for both high- and low-temperature synthesis methods through experiments utilizing time-resolved, in situ imaging and spectroscopy. High-speed videography and pyrometry measured the timeframes for growth for single-wall carbon nanotubes (SWNTs) and nanohorns (SWNHs) by laser vaporization (LV) at 1150 °C, revealing that C can self-assemble at high temperatures preferentially into SWNH structures without catalyst assistance at rates comparable to catalyst-assisted SWNT growth by either laser vaporization or chemical vapor deposition (CVD). Laser interferometry and videography reveal the coordinated growth of vertically-aligned nanotube arrays (VANTAs) by CVD at 550,900 °C. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] | ||||||||||||||||||||||||||||||||||