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1.
J Chem Phys ; 160(11)2024 Mar 21.
Artigo em Inglês | MEDLINE | ID: mdl-38511657

RESUMO

The libration spectrum of liquid H2O is resolved into an octupolar twisting libration band at 485 cm-1 and dipolar rocking-wagging libration bands at 707 and 743 cm-1 using polarization analysis of the hyper-Raman scattering (HRS) spectrum. Dipole interactions and orientation correlation over distances less than 2 nm account for the 36 cm-1 splitting of the longitudinal and transverse polarized bands of the dipolar rocking-wagging libration mode, while the intensity difference observed for the bands is the result of libration correlation over distances larger than 200 nm. The coupled rock and wag libration in water is similar to libration modes in ice. The libration relaxation time determined from the width of the spectrum is 36-54 fs. Polarization analysis of the HRS spectrum also shows long range correlation for molecular orientation and hindered translation, bending and stretching vibrations in water.

2.
J Chem Phys ; 154(3): 034502, 2021 Jan 21.
Artigo em Inglês | MEDLINE | ID: mdl-33499619

RESUMO

Experiments measuring the polarization dependence of hyper-Raman light scattering reveal long-range correlation of molecular vibrations in liquid CCl4. The ν3 and ν1 + ν4 intra-molecular vibrations at about 770 cm-1 are strongly polarized transverse to the scattering wavevector. Weaker transverse polarization is exhibited by the ν1, ν2, and ν4 intra-molecular vibrations and by the inter-molecular collision-induced band around 0 cm-1. The observed polarization dependence is due to the correlation of the vibrations on molecules separated by about 200 nm. The strength of the observed correlation increases with the transition dipole moment for the vibration mode and is consistent with dipole-dipole coupling.

3.
Cytopathology ; 32(5): 621-630, 2021 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-34033159

RESUMO

OBJECTIVE: Rearranged ROS1, present in 1%-2% of non-small cell lung cancer (NSCLC) patients, usually young, never or light smokers, is assessed by fluorescence in situ hybridization (FISH) to determine eligibility for tyrosine kinase inhibitors (TKI). Immunohistochemistry (IHC) for the protein product of ROS1 rearrangement, a cost-effective alternative, is validated on cytology and small biopsy samples. METHODS: From 1 March to 31 December 2019, cytology cell blocks and small biopsy samples from a selected cohort of NSCLC patients were concurrently tested for ROS1 gene rearrangement by Vysis 6q22 Break Apart FISH probe and IHC using Cell Signalling D4D6 antibody. Mismatch cases were tested by an RNA fusion next generation sequencing (NGS) panel. RESULTS: In a prospective population of 95 cases, 91 were negative and two were positive by both FISH and IHC. Both dual positive cases were female never smokers and benefited from TKI treatment. Another two cases were positive by FISH but negative by IHC and repeat by NGS showed one to be negative but one failed. Turnaround time for IHC was 0 to 8 days from request to authorisation, whilst that of FISH was 9 to 42 days at a cost of £51 and £159 respectively. CONCLUSION: IHC to assess for the protein product of ROS1 gene rearrangement on cytology cell blocks and small biopsy samples in a routine setting is a promising screening method to assess eligibility for TKI treatment with positive and indeterminate cases confirmed by FISH or NGS as it has good negative predictive value, faster turnaround time and is cost effective, with proven technical and clinical validation.


Assuntos
Biópsia/métodos , Citodiagnóstico/métodos , Imuno-Histoquímica/métodos , Hibridização in Situ Fluorescente/métodos , Proteínas Tirosina Quinases/metabolismo , Proteínas Proto-Oncogênicas/metabolismo , Adulto , Idoso , Idoso de 80 Anos ou mais , Carcinoma Pulmonar de Células não Pequenas/diagnóstico , Carcinoma Pulmonar de Células não Pequenas/metabolismo , Feminino , Hospitais de Ensino/métodos , Humanos , Neoplasias Pulmonares/diagnóstico , Neoplasias Pulmonares/metabolismo , Masculino , Pessoa de Meia-Idade , Estudos Prospectivos
4.
J Chem Phys ; 152(15): 154301, 2020 Apr 21.
Artigo em Inglês | MEDLINE | ID: mdl-32321264

RESUMO

The second hyperpolarizability (γ) of the H2 molecule was measured by gas-phase electric field induced second harmonic generation at the frequencies of the one-photon resonance for the 3-0 Q(J) overtone transitions (v, J = 0, J → 3, J for J = 0, 1, 2, and 3). The magnitude of the resonant contribution to γ was measured with 2% accuracy using the previously determined non-resonant γ for calibration. Pressure broadening and frequency shift for the transitions were also measured. A theoretical expression for the resonant vibrational γ contribution in terms of transition polarizabilities is compared to the observations. The measured γ resonance strength is 4%-14% larger than the results obtained from this theoretical expression evaluated using ab initio transition polarizabilities.

5.
Toxicol Pathol ; 46(4): 408-420, 2018 06.
Artigo em Inglês | MEDLINE | ID: mdl-29768985

RESUMO

Tanezumab, an anti-nerve growth factor (NGF) antibody, is in development for management of chronic pain. During clinical trials of anti-NGF antibodies, some patients reported unexpected adverse events requiring total joint replacements, resulting in a partial clinical hold on all NGF inhibitors. Three nonclinical toxicology studies were conducted to evaluate the effects of tanezumab or the murine precursor muMab911 on selected bone and joint endpoints and biomarkers in cynomolgus monkeys, Sprague-Dawley rats, and C57BL/6 mice. Joint and bone endpoints included histology, immunohistochemistry, microcomputed tomography (mCT) imaging, and serum biomarkers of bone physiology. Responses of bone endpoints to tanezumab were evaluated in monkeys at 4 to 30 mg/kg/week for 26 weeks and in rats at 0.2 to 10 mg/kg twice weekly for 28 days. The effects of muMab911 at 10 mg/kg/week for 12 weeks on selected bone endpoints were determined in mice. Tanezumab and muMab911 had no adverse effects on any bone or joint parameter. There were no test article-related effects on bone or joint histology, immunohistochemistry, or structure. Reversible, higher osteocalcin concentrations occurred only in the rat study. No deleterious effects were observed in joints or bones in monkeys, rats, or mice administered high doses of tanezumab or muMab911.


Assuntos
Anticorpos Monoclonais Humanizados/toxicidade , Osso e Ossos/efeitos dos fármacos , Articulações/efeitos dos fármacos , Fator de Crescimento Neural/antagonistas & inibidores , Animais , Anticorpos Monoclonais/toxicidade , Macaca fascicularis , Camundongos , Camundongos Endogâmicos C57BL , Ratos , Ratos Sprague-Dawley , Tomografia Computadorizada por Raios X
6.
J Chem Phys ; 149(16): 167102, 2018 Oct 28.
Artigo em Inglês | MEDLINE | ID: mdl-30384729

RESUMO

The Comment proposes that the discrepancy between two second harmonic scattering (SHS) experiments for D2O electrolyte solutions with 100 ns and 190 fs laser pulses is due to unexplained processes for 100 ns pulses that give non-quadratic power dependence for the second harmonic signal. However, the different power dependence of the second harmonic scattering signals measured with 100 ns and 190 fs laser pulses is due to changes in laser beam propagation and focal intensity caused by the combined effect of thermal defocusing and Kerr lens self-focusing. Non-quadratic power dependence does not explain the discrepancy in the second harmonic scattering results.

7.
J Chem Phys ; 149(22): 224504, 2018 Dec 14.
Artigo em Inglês | MEDLINE | ID: mdl-30553264

RESUMO

Third harmonic scattering (THS) from liquids has been observed and analyzed in several recent papers. It is considered to be analogous to second harmonic scattering (hyper-Rayleigh scattering) and to provide a means for measuring the second hyperpolarizability tensor of molecules in a liquid. However, the observed signal for a pure solvent is in fact mainly due to coherent third harmonic generation followed by Rayleigh scattering and direct incoherent THS (direct THS) makes only a small contribution (<2% for parallel polarized THS). This invalidates the internal reference method and the polarization analysis that has been applied for pure liquids. Theoretical comparison for the two processes, extensive experimental measurements for CCl4 liquid, SiO2 glass, and CCl2F2 gas and survey measurements for D2O, CDCl3, CD3CN, and (CD3)2SO liquid, are presented.

8.
J Chem Phys ; 148(13): 134504, 2018 Apr 07.
Artigo em Inglês | MEDLINE | ID: mdl-29626871

RESUMO

Polarization and angle dependence of hyper-Rayleigh scattering (HRS) measured for liquid acetonitrile and dimethyl sulfoxide (DMSO) is analyzed in terms of contributions from randomly oriented molecules and additional contributions produced during intermolecular collisions and induced by the electric field of dissolved ions. All three contributions show the effect of long-range correlation, and the correlation functions are determined using the HRS observations combined with the results of molecular dynamics simulations. HRS from acetonitrile is polarized transverse to the scattering vector. This is due to long-range molecular orientation correlation produced by the dipole-dipole interaction, and correlation at distances r > 100 nm must be included to account for the HRS observations. Analysis of the HRS measurements for acetonitrile determines the length scale a = 0.185 nm for the long-range longitudinal and transverse orientation correlation functions BL=-2BT=a3/r3. Transverse polarized collision-induced HRS is also observed for acetonitrile, indicating long-range correlation of intermolecular modes. Strong longitudinal HRS is induced by the radial electric field of dissolved ions in acetonitrile. For DMSO, the angle between the molecular dipole and the vector part of the first hyperpolarizability tensor is about 100°. As a result, HRS from the randomly oriented molecules in DMSO is nearly unaffected by dipole correlation, and ion-induced HRS is weak. The strong longitudinal polarized HRS observed for DMSO is due to the collision-induced contribution, indicating long-range correlation of intermolecular modes. The HRS observations require correlation that has r-3 long-range asymptotic form, for molecular orientation and for intermolecular vibration and libration, for both acetonitrile and DMSO.

9.
J Biol Chem ; 291(27): 13974-13986, 2016 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-27129258

RESUMO

The prominent role of voltage-gated sodium channel 1.7 (Nav1.7) in nociception was revealed by remarkable human clinical and genetic evidence. Development of potent and subtype-selective inhibitors of this ion channel is crucial for obtaining therapeutically useful analgesic compounds. Microproteins isolated from animal venoms have been identified as promising therapeutic leads for ion channels, because they naturally evolved to be potent ion channel blockers. Here, we report the engineering of highly potent and selective inhibitors of the Nav1.7 channel based on tarantula ceratotoxin-1 (CcoTx1). We utilized a combination of directed evolution, saturation mutagenesis, chemical modification, and rational drug design to obtain higher potency and selectivity to the Nav1.7 channel. The resulting microproteins are highly potent (IC50 to Nav1.7 of 2.5 nm) and selective. We achieved 80- and 20-fold selectivity over the closely related Nav1.2 and Nav1.6 channels, respectively, and the IC50 on skeletal (Nav1.4) and cardiac (Nav1.5) sodium channels is above 3000 nm The lead molecules have the potential for future clinical development as novel therapeutics in the treatment of pain.


Assuntos
Canal de Sódio Disparado por Voltagem NAV1.7/química , Manejo da Dor/métodos , Engenharia de Proteínas , Bloqueadores do Canal de Sódio Disparado por Voltagem/farmacologia , Células HEK293 , Humanos , Canal de Sódio Disparado por Voltagem NAV1.7/efeitos dos fármacos , Técnicas de Patch-Clamp , Filogenia , Venenos de Aranha/química
10.
J Biol Chem ; 291(23): 12254-70, 2016 Jun 03.
Artigo em Inglês | MEDLINE | ID: mdl-27129281

RESUMO

Purinergic homomeric P2X3 and heteromeric P2X2/3 receptors are ligand-gated cation channels activated by ATP. Both receptors are predominantly expressed in nociceptive sensory neurons, and an increase in extracellular ATP concentration under pathological conditions, such as tissue damage or visceral distension, induces channel opening, membrane depolarization, and initiation of pain signaling. Hence, these receptors are considered important therapeutic targets for pain management, and development of selective antagonists is currently progressing. To advance the search for novel analgesics, we have generated a panel of monoclonal antibodies directed against human P2X3 (hP2X3). We have found that these antibodies produce distinct functional effects, depending on the homomeric or heteromeric composition of the target, its kinetic state, and the duration of antibody exposure. The most potent antibody, 12D4, showed an estimated IC50 of 16 nm on hP2X3 after short term exposure (up to 18 min), binding to the inactivated state of the channel to inhibit activity. By contrast, with the same short term application, 12D4 potentiated the slow inactivating current mediated by the heteromeric hP2X2/3 channel. Extending the duration of exposure to ∼20 h resulted in a profound inhibition of both homomeric hP2X3 and heteromeric hP2X2/3 receptors, an effect mediated by efficient antibody-induced internalization of the channel from the plasma membrane. The therapeutic potential of mAb12D4 was assessed in the formalin, complete Freund's adjuvant, and visceral pain models. The efficacy of 12D4 in the visceral hypersensitivity model indicates that antibodies against P2X3 may have therapeutic potential in visceral pain indications.


Assuntos
Anticorpos Monoclonais/farmacologia , Antagonistas do Receptor Purinérgico P2X/farmacologia , Receptores Purinérgicos P2X2/imunologia , Receptores Purinérgicos P2X3/imunologia , Animais , Anticorpos Monoclonais/imunologia , Especificidade de Anticorpos/imunologia , Linhagem Celular Tumoral , Células Cultivadas , Feminino , Adjuvante de Freund , Células HEK293 , Humanos , Inflamação/induzido quimicamente , Inflamação/metabolismo , Inflamação/prevenção & controle , Canais Iônicos/química , Canais Iônicos/metabolismo , Canais Iônicos/fisiologia , Potenciais da Membrana/efeitos dos fármacos , Potenciais da Membrana/fisiologia , Camundongos Endogâmicos BALB C , Microscopia Confocal , Dor/induzido quimicamente , Dor/metabolismo , Dor/prevenção & controle , Multimerização Proteica/imunologia , Ratos , Receptores Purinérgicos P2X2/química , Receptores Purinérgicos P2X2/metabolismo , Receptores Purinérgicos P2X3/química , Receptores Purinérgicos P2X3/metabolismo , Ácido Trinitrobenzenossulfônico , Dor Visceral/induzido quimicamente , Dor Visceral/metabolismo , Dor Visceral/prevenção & controle
11.
Ann Rheum Dis ; 76(1): 295-302, 2017 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-27381034

RESUMO

OBJECTIVE: To investigate whether the effects of nerve growth factor (NGF) inhibition with tanezumab on rats with medial meniscal tear (MMT) effectively model rapidly progressive osteoarthritis (RPOA) observed in clinical trials. METHODS: Male Lewis rats underwent MMT surgery and were treated weekly with tanezumab (0.1, 1 or 10 mg/kg), isotype control or vehicle for 7, 14 or 28 days. Gait deficiency was measured to assess weight-bearing on the operated limb. Joint damage was assessed via histopathology. A second arm, delayed onset of treatment (starting 3-8 weeks after MMT surgery) was used to control for analgesia early in the disease process. A third arm, mid-tibial amputation, evaluated the dependency of the model on weight-bearing. RESULTS: Gait deficiency in untreated rats was present 3-7 days after MMT surgery, with a return to normal weight-bearing by days 14-28. Prophylactic treatment with tanezumab prevented gait deficiency and resulted in more severe cartilage damage. When onset of treatment with tanezumab was delayed to 3-8 weeks after MMT surgery, there was no increase in cartilage damage. Mid-tibial amputation completely prevented cartilage damage in untreated MMT rats. CONCLUSIONS: These data suggest that analgesia due to NGF inhibition during the acute injury phase is responsible for increased voluntary weight-bearing and subsequent cartilage damage in the rat MMT model. This model failed to replicate the hypotrophic bone response observed in tanezumab-treated patients with RPOA.


Assuntos
Anticorpos Monoclonais Humanizados/farmacologia , Cartilagem Articular/lesões , Fator de Crescimento Neural/antagonistas & inibidores , Lesões do Menisco Tibial/tratamento farmacológico , Animais , Anticorpos Monoclonais Humanizados/administração & dosagem , Anticorpos Monoclonais Humanizados/uso terapêutico , Anticorpos Monoclonais Humanizados/toxicidade , Artrite Experimental/induzido quimicamente , Cartilagem Articular/efeitos dos fármacos , Cartilagem Articular/patologia , Cartilagem Articular/fisiopatologia , Modelos Animais de Doenças , Relação Dose-Resposta a Droga , Esquema de Medicação , Avaliação Pré-Clínica de Medicamentos/métodos , Marcha , Masculino , Meniscos Tibiais/diagnóstico por imagem , Meniscos Tibiais/patologia , Radiografia , Ratos Endogâmicos Lew , Lesões do Menisco Tibial/diagnóstico por imagem , Lesões do Menisco Tibial/patologia , Lesões do Menisco Tibial/fisiopatologia , Suporte de Carga , Microtomografia por Raio-X
12.
Bioconjug Chem ; 28(4): 1102-1114, 2017 04 19.
Artigo em Inglês | MEDLINE | ID: mdl-28151644

RESUMO

Antibody drug conjugates (ADCs) provide an efficacious and relatively safe means by which chemotherapeutic agents can be specifically targeted to cancer cells. In addition to the selection of antibody targets, ADCs offer a modular design that allows selection of ADC characteristics through the choice of linker chemistries, toxins, and conjugation sites. Many studies have indicated that release of toxins bound to antibodies via noncleavable linker chemistries relies on the internalization and intracellular trafficking of the ADC. While this can make noncleavable ADCs more stable in the serum, it can also result in lower efficacy when their respective targets are not internalized efficiently or are recycled back to the cell surface following internalization. Here, we show that a lysosomally targeted ADC against the protein APLP2 mediates cell killing, both in vitro and in vivo, more effectively than an ADC against Trop2, a protein with less efficient lysosomal targeting. We also engineered a bispecific ADC with one arm targeting HER2 for the purpose of directing the ADC to tumors, and the other arm targeting APLP2, whose purpose is to direct the ADC to lysosomes for toxin release. This proof-of-concept bispecific ADC demonstrates that this technology can be used to shift the intracellular trafficking of a constitutively recycled target by directing one arm of the antibody against a lysosomally delivered protein. Our data also show limitations of this approach and potential future directions for development.


Assuntos
Sistemas de Liberação de Medicamentos , Imunoconjugados/farmacologia , Lisossomos/metabolismo , Transcitose , Precursor de Proteína beta-Amiloide/imunologia , Precursor de Proteína beta-Amiloide/uso terapêutico , Animais , Anticorpos Biespecíficos/uso terapêutico , Antineoplásicos/química , Linhagem Celular Tumoral , Humanos , Imunoconjugados/metabolismo , Camundongos Nus , Proteínas do Tecido Nervoso/imunologia , Proteínas do Tecido Nervoso/uso terapêutico , Receptor ErbB-2/imunologia , Receptor ErbB-2/uso terapêutico
13.
J Chem Phys ; 147(15): 154501, 2017 Oct 21.
Artigo em Inglês | MEDLINE | ID: mdl-29055332

RESUMO

Second-harmonic or hyper-Rayleigh scattering (HRS) is sensitive to molecular interactions and correlations, and there is a large coherent HRS contribution for water. This work shows that the distinctive angle and polarization dependence observed for HRS from water is due to the long-range orientation correlation of the molecules. The results of HRS experiments for water are analyzed in combination with a molecular dynamics simulation to determine the molecular hyperpolarizability and the short-range and long-range orientation correlation functions for the molecules. At long range, the longitudinal and transverse dipole-dipole orientation correlation functions are BL(r) = -2BT(r) = a3/r3 with a = 0.166 nm. Molecular correlation at distances r > 100 nm must be included to account for the HRS observations.

14.
J Chem Phys ; 147(21): 214505, 2017 Dec 07.
Artigo em Inglês | MEDLINE | ID: mdl-29221415

RESUMO

Long-range ion-induced correlations between water molecules have been observed by second-harmonic or hyper-Rayleigh scattering experiments with conflicting results. The most recent work observed a large difference between the results for H2O and D2O, and large discrepancies with the previously proposed theory. However, the present observations are in quantitative agreement with the model where the ion electric field induces second harmonic generation by the water molecules, and ion-ion correlations given by the Debye-Huckel theory account for intensity saturation at high ion concentration. This work compares experimental results with theory and addresses the apparent discrepancies with previous experiments.

15.
J Chem Phys ; 144(23): 234506, 2016 Jun 21.
Artigo em Inglês | MEDLINE | ID: mdl-27334178

RESUMO

Hyper-Rayleigh scattering (HRS) is sensitive to long-range molecular orientation correlation in isotropic liquids composed of dipolar molecules. Measurements of the polarization, angle, and spectral dependence for HRS from liquid nitrobenzene (NB) are analyzed to determine the NB molecular orientation correlations at long range. The longitudinal and transverse orientation correlation functions for r > 3 nm are BL(r) = (a/r)(3) and BT(r) = - BL(r)/2, where a = 0.20 ± 0.01 nm. Measurements of HRS induced by dissolved ions are also analyzed and combined with molecular dynamics simulation and dielectric response results, to determine the molecular dipole moment µ = 3.90 ± 0.04 D, Kirkwood orientation correlation factor gK = 0.68 ± 0.02, and local field factor f(0) = 0.85 ± 0.04 × Onsager local field factor in liquid nitrobenzene.

16.
Appl Opt ; 55(8): 2071-8, 2016 Mar 10.
Artigo em Inglês | MEDLINE | ID: mdl-26974804

RESUMO

Infrared-absorbing gold black has been selectively patterned onto the active surfaces of a vanadium-oxide-based infrared bolometer array. Patterning by metal lift-off relies on protection of the fragile gold black with an evaporated oxide, which preserves much of gold black's high absorptance. This patterned gold black also survives the dry-etch removal of the sacrificial polyimide used to fabricate the air-bridge bolometers. For our fabricated devices, infrared responsivity is improved 22% in the long-wave IR and 70% in the mid-wave IR by the gold black coating, with no significant change in detector noise, using a 300°C blackbody and 80 Hz chopping rate. The increase in the time constant caused by the additional mass of gold black is ∼15%.

18.
Bioconjug Chem ; 26(4): 650-9, 2015 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-25643134

RESUMO

The systemic stability of the antibody-drug linker is crucial for delivery of an intact antibody-drug conjugate (ADC) to target-expressing tumors. Linkers stable in circulation but readily processed in the target cell are necessary for both safety and potency of the delivered conjugate. Here, we report a range of stabilities for an auristatin-based payload site-specifically attached through a cleavable valine-citrulline-p-aminobenzylcarbamate (VC-PABC) linker across various sites on an antibody. We demonstrate that the conjugation site plays an important role in determining VC-PABC linker stability in mouse plasma, and that the stability of the linker positively correlates with ADC cytotoxic potency both in vitro and in vivo. Furthermore, we show that the VC-PABC cleavage in mouse plasma is not mediated by Cathepsin B, the protease thought to be primarily responsible for linker processing in the lysosomal degradation pathway. Although the VC-PABC cleavage is not detected in primate plasma in vitro, linker stabilization in the mouse is an essential prerequisite for designing successful efficacy and safety studies in rodents during preclinical stages of ADC programs. The divergence of linker metabolism in mouse plasma and its intracellular cleavage offers an opportunity for linker optimization in the circulation without compromising its efficient payload release in the target cell.


Assuntos
Aminobenzoatos/química , Anticorpos Monoclonais/química , Antineoplásicos/química , Imunoconjugados/química , Oligopeptídeos/química , Neoplasias Pancreáticas/tratamento farmacológico , Aminobenzoatos/sangue , Aminobenzoatos/farmacocinética , Aminobenzoatos/farmacologia , Animais , Antineoplásicos/sangue , Antineoplásicos/farmacocinética , Antineoplásicos/farmacologia , Carbamatos/química , Catepsina B/química , Catepsina B/metabolismo , Linhagem Celular Tumoral , Dipeptídeos/química , Sistemas de Liberação de Medicamentos/métodos , Estabilidade de Medicamentos , Feminino , Humanos , Imunoconjugados/sangue , Imunoconjugados/farmacocinética , Imunoconjugados/farmacologia , Camundongos , Camundongos Nus , Modelos Moleculares , Oligopeptídeos/sangue , Oligopeptídeos/farmacocinética , Oligopeptídeos/farmacologia , Neoplasias Pancreáticas/sangue , Neoplasias Pancreáticas/patologia , Relação Estrutura-Atividade , Ensaios Antitumorais Modelo de Xenoenxerto
19.
J Chem Phys ; 143(13): 134503, 2015 Oct 07.
Artigo em Inglês | MEDLINE | ID: mdl-26450319

RESUMO

Hyper-Rayleigh scattering (HRS) is sensitive to long-range molecular orientation correlation in isotropic liquids composed of dipolar molecules. The correlation functions that appear in the calculation of HRS mediated by the vector part of the first hyperpolarizability ß are the same as the correlation functions for the homogeneous isotropic random vector fields that appear in the description of fluid turbulence. Recent experiments measuring the angle and polarization dependence of HRS from water find a dominant transverse mode contribution with amplitude independent of the scattering wavevector, and this observation of transverse mode HRS strongly constrains the form of the orientation correlation function. Analysis of these HRS results for water determines that the long-range molecular orientation correlation function varies as r(-3±Îµ) with |ε| < 0.03 on spatial scales up to 2000 nm.

20.
J Chem Phys ; 143(22): 224307, 2015 Dec 14.
Artigo em Inglês | MEDLINE | ID: mdl-26671375

RESUMO

The third-order nonlinear-optical susceptibility of dimethyl ether, (CH3)2O, has been measured in the gas phase over the wavelength range 488 nm < λ < 1064 nm using the technique of gas-phase electric-field-induced second-harmonic generation with periodic phase matching and with N2 as the reference gas. Measurements span a range of temperature, which allows for separation of the temperature-independent second hyperpolarizability term from the temperature-dependent first hyperpolarizability term. The dispersion curves of the isotropically averaged first and second hyperpolarizabilities (ß and γ) are deduced.

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