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The origin of the lattice thermal conductivity enhancement at the ferroelectric phase transition in GeTe

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npj Computational Materials 2021年第1期7卷 529-536页

作者： Đorđe Dangić Olle hellman Stephen Fahy Ivana Savić Department of Physics University College CorkCorkIreland Tyndall National Institute CorkIreland Department of Physics Chemistry and Biology(IFM)Linköping UniversityLinköpingSweden

The proximity to structural phase transitions in IV-VI thermoelectric materials is one of the main reasons for their large phonon anharmonicity and intrinsically low lattice thermal conductivityκ.however,theκof GeTe increases at the ferroelectric phase transition near 700 *** first-principles calculations with the temperature dependent effective potential method,we show that this rise inκis the consequence of negative thermal expansion in the rhombohedral phase and increase in the phonon lifetimes in the high-symmetry *** anharmonicity near the phase transition induces non-Lorentzian shapes of the phonon power *** account for these effects,we implement a method of calculatingκbased on the Green-Kubo approach and find that the Boltzmann transport equation underestimatesκnear the phase *** findings elucidate the influence of structural phase transitions onκand provide guidance for design of better thermoelectric materials.

关键词： phase transition ferroelectric

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种族面面观

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Novel histological Evidence of Collagen and Elastin Regeneration in Fractional RF-Treated Acne Scars

1973年

作者：克拉斯（M.Klass）赫尔曼（h.hellman）胡叔仁译

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Journal of Cosmetics, Dermatological Sciences and Applications 2019年第2期9卷 155-164页

作者： Judith.hellman Jonathan Yao Mt. Sinai hospital New York USA Schweiger Dermatology Group New York USA

Introduction: Fractional radiofrequency (RF) technology has been shown to be a gold standard therapy for acne scars. We have previously published clinical and histological results from the treatment of 8 patients with active acne and acne related scarring using a fractional RF device. Evidence of safety and efficacy was demonstrated, including long term follow-up clinical results from 4 patients, up to two years post last fractional treatment. In the current article we present histology evidence of acne scar skin renewal 3.5 years post treatment. Methods: Skin biopsies from acne scars in a concealed facial area were taken before, after four treatments and at 3.5 years after the last fractional treatment. Biopsies were examined with standard hematoxylin and eosin (h&E) stain, as well as Verhoeff’s Van Gieson (VVG) and Shikata stains for elastic fibers. Results: histological findings demonstrate regeneration of elastic fibers and reduction of the dermal fibrosis. Scar depth of Patient #2 was reduced by 80% in the corresponding follow-up period. Conclusion: The long-term histological results further support the previously published findings that fractional RF is a safe and effective treatment for acne related scars.

关键词： Fractional Radiofrequency Acne Scars histological Evidence Long Term Follow-Up Elastic Fibers Regeneration

Clinical Evaluation of a Novel Blended Mode Diode Laser for hair Removal

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Journal of Cosmetics, Dermatological Sciences and Applications 2019年第1期9卷 19-29页

作者： Michael h. Gold Judith.hellman Serge Dahan R. Stephen Mulholland Tennessee Clinical Research Center Nashville USA Mt. Sinai hospital New York USA Jean Languedoc Clinic Toulouse France Private Aesthetic Plastic Surgery Practice SpaMedica Toronto Canada

Introduction: Photoepilation by lasers is a popular procedure in aesthetic dermatology for removing unwanted body and facial hair. The use of the most appropriate laser wavelength is crucial as it affects treatment depth and melanin absorption. The three commonly used hair removal lasers are of specific wavelengths: 755 nm, 810 nm, and 1064 nm, each preferred certain types of skin and hair characteristics. The current evaluation reports the safety and efficacy of unique blended modes 755/810 nm and 810/1064 nm diode lasers for hair removal. Methods: hair removal results from 50 patients treated with the 755/810 nm handpiece and 50 patients treated with the 810/1064 nm handpiece were gathered from a few clinics. 3 treatments on various body areas were conducted 6 weeks apart and patients were followed up with 6 months after the last treatment. Results were evaluated by baseline, follow-up photographs, and hair counts. Results: Treatment area photos demonstrated hair reduction in the treated body and facial areas. Average hair count reduction at 6 months follow-up was 84% for the 755/810 nm handpiece and 81% for the 810/1064 nm handpiece. No significant or unexpected adverse events were detected in any of the patients. Conclusions: The novel blended mode hair removal diode lasers are proven to be safe and effective for hair removal in facial and body areas for patients of various skin types and hair characteristics.

关键词： Laser hair Removal 755 nm Diode Laser 810 nm Diode Laser 1064 nm Diode Laser

Layer resolved magnetization reversal study in SmCo_5 /Fe nanocomposite bilayers

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Chinese Physics B 2010年第3期19卷 528-532页

作者： F.Shahzad S.A.Siddiqi M.Y.Im A.Avallone P.Fischer Z.hussain I.Siddiqi F.hellman Centre for Solid State Physics University of the PunjabLahore-54590Pakistan Center for X-ray Optics Lawrence Berkeley National LaboratoryBerkeleyCA 94720USA Advanced Light Source Berkeley LaboratoryUniversity of CaliforniaBerkeleyCA-94720USA Department of Physics University of CaliforniaBerkeleyCalifornia-94720USA

A hard/soft SmCo5/ Fe nanocomposite magnetic bilayer system is fabricated on x-ray transparent 100-200 nm thin SiaN4 films by magnetron sputtering. The microscopic magnetic domain pattern and its behaviours during magnetization reversal in the hard and the soft magnetic phases are studied separately by element specific magnetic soft x-ray microscopy at a spatial resolution of better than 25 Nm. We observe that the domain patterns for the soft and hard phases show coherent behaviours in varying magnetic fields. We derive local M（h） curves from the images of Fe and SmCo5 separately and find the switches for hard and soft phases to be the same.

关键词： multilayers x-ray microscopes magnetic properties of nanostructures

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导弹是怎样飞向目标的

导弹是怎样飞向目标的

作者：哈尔·赫尔曼(h. hellman)

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真实地带十大科学争论 1版

丛书名：世纪人文系列丛书

2005年

作者：（美）哈尔·赫尔曼（hal hellman）赵乐静译

本书旨在纠正人们过分理想化地将科学当成了远离失败的伟大历程这种一孔之见。书中收录17～20世纪科学史上有影响的十大科学论战，生动再现了科学发展的真实历史。

ISBN: (纸本)7532378012

关键词：自然科学史世界

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真实地带十大科学争论第1版

Preparation of the Rutin-SBA-16 Drug Delivery System

丛书名： View.新视角书系

2000年

作者：（美）哈尔·赫尔曼（hal hellman）赵乐静译

本书撷取17～20世纪科学史上有影响的十次科学论战，以浅显明晰、引人入胜的语言，向读者展现了一幅跌宕起伏、激动人心的画卷，生动地再现了科学发展的真实历史。

ISBN: (纸本)753235427X

关键词：自然科学史地点:世界

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Journal of Biomaterials and Nanobiotechnology 2020年第1期11卷 1-13页

作者： Juliana Camila Fischer Karnopp Teofilo Fernando Mazon Cardoso Daniel Araujo Goncalves Aline Regina hellman Carollo Gustavo Rocha de Castro Adriana Pereira Duarte Marco Antonio Utrera Martines Institute of Chemistry Federal University of Mato Grosso do SulCidade UniversitariaCampo GrandeMSBrazil Faculty of Pharmaceutical Sciences Food and NutritionFederal University of Mato Grosso do SulCidade UniversitariaCampo GrandeMSBrazil Department of Chemistry Minas Gerais State UniversityItuiutabaMGBrazil Institute of Biosciences Sao Paulo State UniversityBotucatuSPBrazil

This study sets out a scheme for a controlled release delivery system using SBA-16 as a carrier matrix and Rutin as a drug (Rutin-SBA-16). Physicochemical characterizations were performed to confirm the structure of the SBA-16 for post-synthesis by scanning electron microscopy (SEM), Transmission Electron Microscopy (TEM) and X-ray Diffraction (XRD). The presence of Rutin-SBA-16 was confirmed by Fourier-transform infrared spectroscopy (FTIR) and Nitrogen adsorption-desorption isotherms at 77 K. The dissolution kinetics was evaluated by the Zero Order, First Order and higuchi models, and Rutin quantification was carried out by high Performance Liquid Chromatography (hPLC). The best impregnation time, which was 8 hours, adsorbing 284 μg Rutin per mg of silica, and the maximum degree of dissolution occurred in a period of 20 - 25 h. The release kinetics of the Rutin was called higuchi, and showed high linearity, with a correlation coefficient (R2) of 0.999 compared with 0.905 and 0.980 of the zero order and first order models respectively. The study shows the benefits of Rutin-SBA-16 as a drug delivery system.

关键词： Rutin Controlled Release Systems Kinetic Study Mesoporous Silica Flavonoid