bluuebunny/crossref_metadata_2025_split huggingface dataset:
Treatment of Nevus of Ota in Fitzpatrick skin type VI with the 1064‐nm QS Nd:YAG laser
Authors: Landau Jennifer M. , Vergilis‐Kalner Irene , Goldberg Leonard H. , Geronemus Roy G. , Friedman Paul M. 
Published: March 2011

AbstractBackgroundNevus of Ota is a pigmented lesion that usually presents at birth. Due to a greater risk for complications, physicians have not always utilized laser therapy to treat these nevi in patients with darker skin types.ObjectiveTo evaluate the safety and efficacy of the 1,064‐nm Q‐switched neodymium‐doped yttrium aluminium garnet (QS Nd:YAG) laser for the treatment of Nevus of Ota in two patients with Fitzpatrick skin type (FST) VI.ResultsAfter 4–13 treatment sessions with the 1,064‐nm Q‐switched Nd:YAG laser with a 4 mm spot size and fluence of 4–4.2 J/cm2, two patients with FST VI noted substantial improvement in the appearance of the nevi.ConclusionAt conservative treatment settings, these two case reports have shown that the 1,064‐nm QS Nd:YAG laser can be utilized to safely and effectively treat Nevus of Ota in individuals with FST IV–VI. Lasers Surg. Med. 42:65–67, 2011 © 2011 Wiley‐Liss, Inc.
An intra‐individual quantitative assessment of acute laser injury patterns in facial versus abdominal skin
Authors: Bailey Steven H. , Brown Spencer A. , Kim Yeonsoon , Oni Georgette , Abtahi Fatemeh , Richardson James A. , Hoopman John , Barton Fritz , Kenkel Jeffrey M. 
Published: March 2011

AbstractIntroductionClinical laser settings have traditionally been calibrated on abdominal skin to predict and anticipate patterns of injuries in facial skin. This experimental approach has limitations as facial skin and abdominal skin have differences that may influence the depth of laser injury.ObjectiveThe primary objective of this study is to analyze the acute pattern of laser injury in abdominal skin and facial skin samples from the same subject and detail the anatomical and biophysical properties that can influence the laser tissue interaction. The secondary objective is to develop a conversion factor that will allow the prediction laser column depths in facial skin based upon laser column depths in abdominal skin.MethodsFifteen healthy subjects were consented and screened. Two 2 mm spots on the face and abdomen were identified and measured and treated with a fractional CO2 laser (Lumenis Ltd, Yokneum, Israel), with an energy setting of 15 mj, 300 Hz at a density of 10. Treatment areas were biopsied and analyzed histologically using hematoxylin and eosin and TUNEL staining.ResultsFacial skin and abdominal skin have several significant anatomical and biophysical differences (concentration of pilosebaceous units, sebum concentration, and moisture content). Facial tissue demonstrated divergence of laser energy around pilosebaceous units and lateral spread of laser energy along blood vessels. These differences cause attenuation (28%) of the laser energy and result in column depths that are significantly (P < 0.003) shorter in facial tissues (mean depth 415 µm) in comparison to abdominal tissues (mean depth 582 µm).ConclusionThe variations in anatomic, biophysical, and biomechanical properties in facial skin cause an attenuation of the laser column depths in facial skin when compared to abdominal skin. A correction factor of 28% is required to predict the depth of laser columns in facial skin based on laser column depths observed in abdominal skin. Lasers Surg. Med. 42:99–107, 2011 © 2011 Wiley‐Liss, Inc.
Characterization of an optimized light source and comparison to pulsed dye laser for superficial and deep vessel clearance
Authors: Weiss Robert A. , Ross E. Victor , Tanghetti Emil A. , Vasily David B. , Childs James J. , Smirnov Mikhail Z. , Altshuler Gregory B. 
Published: March 2011

AbstractBackground and ObjectiveAn arc lamp‐based device providing optimized spectrum and pulse shape was characterized and compared with two pulsed dye laser (PDL) systems using a vascular phantom. Safety and effectiveness for facial telangiectasia are presented in clinical case studies.Study Design/Materials and MethodsAn optimized pulsed light source's (OPL) spectral and power output were characterized and compared with two 595 nm PDL devices. Purpuric threshold fluences were determined for the OPL and PDLs on Fitzpatrick type II normal skin. A vascular phantom comprising blood‐filled quartz capillaries beneath porcine skin was treated by the devices at their respective purpuric threshold fluences for 3 ms pulse widths, while vessel temperatures were monitored with an infrared (IR) camera. Patients with Fitzpatrick skin types II–III received a split‐face treatment with the OPL and a 595 nm PDL.ResultsThe OPL provided a dual‐band output spectrum from 500 to 670 nm and 850–1,200 nm, pulse widths from 3 to 100 ms, and fluences to 80 J/cm2. The smooth output power measured during all pulse widths provides unambiguous vessel size selectivity. Percent energy in the near infra‐red increased with decreasing output power from 45% to 60% and contributed 15–26% to heating of deep vessels, respectively. At purpuric threshold fluences the ratio of OPL to PDL vessel temperature rise was 1.7–2.8. OPL treatments of facial telangiectasia were well‐tolerated by patients demonstrating significant improvements comparable to PDL with no downtime.ConclusionsIntense pulsed light (IPL) and PDL output pulse and spectral profiles are important for selective treatment of vessels in vascular lesions. The OPL's margin between purpuric threshold fluence and treatment fluence for deeper, larger vessels was greater than the corresponding margin with PDLs. The results warrant further comparison studies with IPLs and other PDLs. Lasers Surg. Med. 42:92–98, 2011 © 2011 Wiley‐Liss, Inc.
A clinical instrument for combined raman spectroscopy‐optical coherence tomography of skin cancers
Authors: Patil Chetan A. , Kirshnamoorthi Harish , Ellis Darrel L. , van Leeuwen Ton G. , Mahadevan‐Jansen Anita 
Published: March 2011

AbstractBackground and ObjectiveThe current standard for diagnosis of skin cancers is visual inspection followed by biopsy and histopathology. This process can be invasive, subjective, time consuming, and costly. Optical techniques, including Optical Coherence Tomography (OCT) and Raman Spectroscopy (RS), have been developed to perform non‐invasive characterization of skin lesions based on either morphological or biochemical features of disease. The objective of this work is to report a clinical instrument capable of both morphological and biochemical characterization of skin cancers with RS‐OCT.Materials and MethodsThe portable instrument utilizes independent 785 nm RS and 1,310 nm OCT system backbones. The two modalities are integrated in a 4″ (H) × 5″(W) × 8″(L) clinical probe. The probe enables sequential acquisition of co‐registered OCT and RS data sets. The axial response of the RS collection in the skin was estimated using scattering phantoms. In addition, RS‐OCT data from patients with cancerous and non‐cancerous lesions are reported.ResultsThe RS‐OCT instrument is capable of screening areas as large as 15 mm (transverse) by 2.4 mm (in depth) at up to 8 frames/second with OCT, and identifying locations to perform RS. RS signal is collected from a 44 µm transverse spot through a depth of approximately 530 µm. RS‐OCT data sets from a superficial scar and a nodular BCC are reported to demonstrate the clinical potential of the instrument.ConclusionThe RS‐OCT instrument reported here is capable of morphological and biochemical characterization of cancerous skin lesions in a clinical setting. OCT can visualize microstructural irregularities and perform an initial morphological analysis of the lesion. The images can be used to guide acquisition of biochemically specific Raman spectra. The two data sets can then be evaluated with respect to one another to take advantage of the mutually complimentary nature of RS and OCT. Lasers Surg. Med. 42:143–151, 2011 © 2011 Wiley‐Liss, Inc.
Detection and management of latent tuberculosis in liver transplant patients
Authors: Jafri Syed-Mohammed , Singal Amit G. , Kaul Daniel , Fontana Robert John 
Published: March 2011

Abstract

The optimal means for detecting and managing liver transplantation (LT) patients with latent tuberculosis (TB) are not well defined. Our study aims were to (1) determine the frequency and risk factors of latent TB in a large cohort of consecutive adult LT candidates and (2) determine the safety and efficacy of isoniazid treatment in LT recipients with latent TB. A review of patients assessed for latent TB by skin testing using purified protein derivative (PPD; January 2004 to September 2008) or with the interferon-γ release assay QuantiFERON-TB Gold (QFT; March 2008 to October 2009) was undertaken. The baseline clinical features and outcomes of subjects with latent TB and subjects without latent TB were compared. Twenty-five of 420 subjects (6.0%) were positive for PPD. In comparison, 11 of 119 subjects (9.2%) had a positive QFT assay, and 15 others (13%) had indeterminate results. Both PPD-positive and QFT-positive subjects were less likely to be Caucasian than subjects without latent TB (p < 0.001). The 3-year survival rate of the 25 LT recipients with latent TB was similar to that of the 296 LT recipients without latent TB (78.7% versus 74.6%, P = 0.58). Fifteen of the 25 latent TB patients received isoniazid at a mean of 0.67 months after LT. Although isoniazid was discontinued in 8 subjects because of possible side effects, none of the 25 latent TB patients developed TB reactivation after transplantation with a mean follow-up of 33 months. In conclusion, both QFT testing and PPD testing demonstrate similar rates of detecting latent TB infection in American LT candidates, but QFT testing also leads to a moderate rate of indeterminate test results. Early isoniazid chemoprophylaxis after LT is poorly tolerated and is frequently discontinued. Liver Transpl, 2011. © 2011 AASLD.
Building high‐trust organizations
Authors: Shockley‐Zalabak Pamela S. , Morreale Sherwyn P. 
Published: March 2011

AbstractThis article presents a model for trust building in organizations that is both research‐based and practice‐driven; it is designed to help organizations produce the staying power that only trust can generate. The authors explain the five key drivers of trust: competence, openness and honesty, concern for employees and stakeholders, reliability, and identification.
Moving Up: Ten questions for leaders in transition (Part II)
Authors: Bruce Shaw Robert , Chayes Michael M. 
Published: March 2011

AbstractPart I of this article (in Leader to Leader, No. 59, Winter 2011) discussed the four stages of a successful transition into a new leadership role, with a focus on an initial “discovery” phase. In Part II of the article, the authors discuss the questions that each new leader will need to answer in the remaining three transitional stages: Define: Mapping out key priorities and strategies; Deliver: Sustaining focus and ensuring progress; and Build: Building productive relationships with stakeholders.
Template polymerization by free radical mechanisms
Authors: Tan Y. Yong , Challa Ger 
Published: March 2011

AbstractA polymerization in which propagation can proceed along macromolecular templates, is termed template polymerization. As compared to the blank (i.e. conventional) polymerization such a propagation, made possible through cooperative interaction, affects the kinetics of the reaction and the structural features of the formed (daughter) polymer. This is called template effect. Template systems can be classified according to the degree of monomer adsorption on the template which is characterized by the Langmuir equilibrium constant KM. In type I systems where KM = ∞ propagation proceeds exclusively by addition of adsorbed monomer arrays; in type II systems with KM = 0 propagation proceeds exclusively by addition of monomer molecules from solution. Such extreme cases are rare, however. Since most template systems have finite values between very large and very small, a generalized kinetic model for free‐radical template polymerizations has been developed from the type II model. Examples are given to illustrate the application of the generalized model. Some attention is paid to the structural features (average molecular weight and tacticity) of the daughter polymers, as well as to template copolymerization.
Microscopic kinetic events in emulsion polymerization
Authors: Napper Donald H. , Gilbert Robert G. 
Published: March 2011

AbstractExperimental methods are reviewed which enable the microscopic kinetic events that underpin the formation of polymer latex particles and their subsequent growth in emulsion polymerizations to be explored. The growth of latex particles is the simpler of these two processes and considerable insight has now been gained into the mechanisms of the entry of free radicals into latex particles, the exit of free radicals therefrom, the fate of the exited free radicals and bimolecular termination events in the latex particles. Some progress has been made in modelling these processes theoretically. The formation of latex particles is a more complex phenomenon. The classical picture of latex particle formation occurring by the entry of free radicals into surfactant micelles appears to lack experimental substantiation. Particle size distribution results, which contain information about the rate of production of latex particles, imply that particles are generated by a multi‐step process which involves the coagulation of immature precursor particles. A semi‐quantitative theory for coagulative nucleation has been developed which predicts the general features of a broad range of nucleation phenomena.
Light‐induced cationic polymerization
Authors: Yagci Yusuf , Schnabel Wolfram 
Published: March 2011

AbstractMechanistic studies concerning the initiation of cationic chain reactions with the aid of diaryliodonium and triarylsulphonium salts are reviewed and recent results are presented. Laser flash photolysis in combination with pulse radiolysis experiments revealed evidence for a triplet path occurring parallel to the singlet deactivation route of electronically excited diphenyliodonium ions. The radical cations PhI+− and Ph2S+− were found to react selectively with nucleophiles, the former being more reactive than the latter. Moreover, various aspects of the photo‐initiated free radical‐promoted cationic polymerization of typical monomers such as tetrahydrofuran and butyl vinyl ether with the aid of acylphosphine oxides and other free radical initiators are discussed.
Cationic degradation of polysulfides and polyethers by chemical initiators and irradiation
Authors: Goethals E. J. , van Meirvenne D. , De Clercq R. 
Published: March 2011

AbstractDegradation of polyacetals, polyoxiranes, polythiiranes, poly(ethylene disulfides) and poly(alkylene sulfides), initiated by cationic initiators, is a general phenomenom. The polyacetals lead to a mixture of monomer and cyclic oligomers; the polyoxiranes mainly to cyclic dimers. Cationic degradation of polythiiranes and poly(ethylene disulfides) leads to a variety of cyclic compounds the nature of which depends on the monomer substituents. Poly(alkylene sulfides) form the corresponding thiacycloalkanes. The mechanism of these degradations and the influence of substituents on the degradation products have been studied. Preliminary results on U.V. ‐ initiated cationic degradation of polythiiranes are reported.
Pseudo‐cationic polymerisation after 24 years
Authors: Plesch Peter H. 
Published: March 2011

AbstractIt is shown that the theory of pseudo‐cationic polymerisation is now well established. This is because it can account for old and new observations, including the living polymerisations initiated by Giusti's syncatalytic system (I2 + HI); and because attempts at disproving it have been unsuccessful. The theory's essential part is that in certain cationoid polymerisations the propagating species is an ester (which may be stabilised or activated), and that the propagation step involves the insertion of the monomer into a polarised covalent bond. It is made clear that the pseudo‐cationic theory is merely a generalisation of reaction mechanisms which are well known and uncontroversial in conventional organic chemistry. Ten experimental facts are analysed to show the relevance and plausibility of the pseudo‐cationic theory.The two main versions of the “ions‐at‐any‐price” rival theories, namely the “large concentration of invisible ions” view and the “minute concentration of conventional carbenium ions” view are both shown to be incompatible with all the facts. It is emphasised that many industrial cationoid oligomerisations and polymerisations are pseudo‐cationic.
Living carbocationic polymerization XIV. Living polymerization of isobutylene with ester‐TiCl4 complexes
Authors: Kaszás Gabor , Puskás Judit , Kennedy Joseph P. 
Published: March 2011

AbstractThe living polymerization of isobutylene (IB) has been induced by cumyl acetate·TiCl4 and cumyl propionate·TiCl4 complexes in CH2Cl2/n‐C6H14 and CH3Cl/n‐C6 H14 mixtures under conventional laboratory conditions at −40°C. The living nature of the polymerization was demonstrated by linear M̄n versus Wp (g PIB formed) plots starting at the origin. DPn obeys [IB]/[cumyl acetate·TiCl4] and molecular weight distributions (MWD) are very narrow, M̄w/M̄n = 1.05–1.13. PIBs having M̄n >40000 have been prepared. The effects of the nature of the solvent, solvent composition, nature of the ester, ester/TiCl4 ratio and concentrations on rates, M̄ns and MWDs have been investigated. The living polymerization is faster by the cumyl acetate‐TiCl4 than by the cumyl propionate·TiCl4 complex. The rate of living polymerizations is negligible at CuAc/TiCl4 = 1 and increases significantly in the presence of stoichiometric excess of TiCl4 over the ester. Undesirable initiation due to protogenic impurities can be suppressed by employing relatively nonpolar (hexane‐rich) media, by increasing the ester/TiCl4, ratio, or by the addition of a non‐initiating ester (ethyl acetate); however, the rates decrease as a consequence of these measures. Polymerizations induced by mixtures of cumyl acetate·TiCl4/cumyl propionate·TiCl4 complexes yield monomodal narrow MWDs indicating rapid ester exchange at the growing site which in turn suggests ionic active species. The kinetic findings are explained by a mechanistic scheme that rests on two propositions: Propagation involves activated (most probably ionized) polymer‐ester·Lewis acid complexes, and free (uncomplexed) Lewis acid causes irreversible destruction of living propagation.
Macromonomers on the basis of 2‐phenyl‐2‐oxazoline
Authors: Schulz Rolf C. , Schwarzenbach Elmar 
Published: March 2011

AbstractBy initiation of the ring‐opening polymerization of 2‐phenyl‐2‐oxazoline (1) with p‐iodomethylstyrene a macromonomer with a styrene end‐group (2) is obtained. The degree of polymerization was varied between 10 and 16. The radical copolymerization of 2 with styrene is described. 1 forms with methyl triflate a very stable oxazolinium salt which is a good initiator for the bulk polymerization of 1 at temperatures of 50–70°C. It was conclusively proved that under these conditions the polymerization proceeds by a living mechanism. By termination with N, N‐dimethylaminopropylmeth‐acrylamide a macromonomer (5) was obtained. 5 can be radically homopolymerized. This comb‐like polymer 6 has the typical behaviour of a poly‐electrolyte and a polymeric amphiphile.
High‐conversion emulsion, dispersion and suspension polymerization
Authors: Adams Mary E , Casey Brendan S , Mills Martin F , Russell Gregory T , Napper Donald H , Gilbert Robert G 
Published: March 2011

AbstractSome of the distinguishing features of emulsion polymerization kinetics at high conversion are discussed. The apparent anomaly that propagation rate coefficients deduced from bulk and emulsion systems at high conversion are greatly different actually arises because the initiator efficiency in the former is very low. At intermediate and at high conversions, termination kinetics must take account of the length of each terminating chain; data and a new theoretical model for this are found to be in accord. Modelling the reaction‐diffusion equations at high conversion (including new theory to account for polymer migration) shows that large (say, >200 nm radius) particles at high conversion will show strong spatial inhomogeneity (core‐shell structure) even in emulsion homopolymerizations, because of the slow diffusion of monomer and free radicals.
A kinetic and mechanistic study of the early stage of emulsion copolymerization of styrene and methyl methacrylate
Authors: Nomura Mamoru , Takahashi Koichi , Fujita Kazumi 
Published: March 2011

AbstractKinetic and mechanistic features in the early stage of the emulsion copolymerization of styrene and methyl methacrylate were examined using sodium lauryl sulfate and potassium peroxidisulfate as emulsifier and initiator, respectively. Experimental results on copolymer composition, molecular weight distribution, the rate of copolymerization and the number of polymer particles found in the early stage of the reaction showed that: (1) The amount of copolymers produced in the water phase decreases with an increase in the concentration of emulsifier initially charged and can be practically neglected above the critical micelle concentration(CMC), and hence, (2) Polymer particles are regarded to be produced mainly from the emulsifier micelles sufficiently above the CMC. (3) Coagulation of polymer particles can be neglected in the process of particle nucleation.
Modeling emulsion copolymerization: Crosslinking kinetics
Authors: Tobita H. , Hamielec A. E. 
Published: March 2011

AbstractThe authors' kinetic models for network formation in free radical polymerization both for pre‐ and post‐gelation periods are re‐examined and extended to include high mole fractions of divinyl monomer. Network formation in free radical polymerization is a non‐equilibrium process, namely, it is kinetically controlled, and therefore, the crosslinking density of a primary polymer molecule depends on its history. The crosslinking process is responsible for a distribution of crosslinking density with crosslinking density a function of the birth time of a primary polymer molecule. The crosslinking density distribution is an important feature of network formation in free radical polymerization. Under special rather limiting conditions the present kinetic models reduce to Flory's theory of network formation in which an equilibrium system is assumed. These kinetic approaches provide great insight into the phenomena of network formation, and they can readily be applied to emulsion polymerization.
Modeling of molecular weight distribution and microstructure of copolymers prepared in emulsion
Authors: Storti Giuseppe , Polotti Gianmarco , Canu Paolo , Carrá Sergio , Morbidelli Massimo 
Published: March 2011

AbstractA stochastic model for evaluating Molecular Weight Distribution (MWD) and Chain Composition Distribution (CCD) of copolymers prepared in emulsion is applied to a “zero‐one‐two” binary system, i.e. with no more than two active chains per particle. Model predictions are compared with those by widely applied literature models based on bulk polymerization equations for evaluating CCD and on simplifying approaches for MWD (Refs. 5 and 6). For the particular system under examination, the range of reliable applicability of these approximated models is limited to high molecular weights (average degrees of polymerization larger than about 500 units), while for shorter chains the model here reported has to be used.