Marcus Cicerone - Academia.edu (original) (raw)

Papers by Marcus Cicerone

While the structural basis of protein function is well understood in the biopharmaceutical and bi... more While the structural basis of protein function is well understood in the biopharmaceutical and biotechnology industries, few methods for the characterization and comparison of protein conformation distributions are available. New methods capable of measuring the stability of protein conformations and the integrity of protein-protein, protein-ligand and protein-surface interactions both in solution and on surfaces are needed to help the development

Coherent anti-Stokes Raman scattering (CARS) microscopy has exciting potential for rapid chemical... more Coherent anti-Stokes Raman scattering (CARS) microscopy has exciting potential for rapid chemical imaging of materials and noninvasive imaging of biological systems, both in-vivo, and as these systems interact with materials. Although CARS is as much as 10^6 times more sensitive that spontaneous Raman scattering, it is accompanied by a nonresonant background (NRB) signal which can mask the resonant signal of

Multiphoton Microscopy in the Biomedical Sciences IX, 2009

The Journal of Physical Chemistry, 1993

ABSTRACT

Molecular pharmaceutics, Jan 18, 2015

Nanosecond relaxation processes in sugar matrices are causally linked through diffusional process... more Nanosecond relaxation processes in sugar matrices are causally linked through diffusional processes to protein stability in lyophilized formulations. Long-term protein degradation rates track mean-squared displacement (⟨u(2)⟩) of hydrogen atoms in sugar glasses, a parameter describing dynamics on a time scale of picoseconds to nanoseconds. However, measurements of ⟨u(2)⟩ are usually performed by neutron scattering, which is not conducive to rapid formulation screening in early development. Here, we present a benchtop technique to derive a ⟨u(2)⟩ surrogate based on the fluorescence red edge effect. Glycerol, lyophilized trehalose, and lyophilized sucrose were used as model systems. Samples containing 10(-6) mole fraction of rhodamine 6G, a fluorophore, were excited at either 532 nm (main peak) or 566 nm (red edge), and the ⟨u(2)⟩ surrogate was determined based the corresponding Stokes shifts. Results showed reasonable agreement between ⟨u(2)⟩ from neutron scattering and the surrogate...

Physical review letters, Jan 12, 2014

We show that incoherent quasielastic neutron scattering from molecular liquids reveals a two-stat... more We show that incoherent quasielastic neutron scattering from molecular liquids reveals a two-state dynamic heterogeneity on a 1 ps time scale, where molecules are either highly confined or are free to undergo relatively large excursions. Data ranging from deep in the glassy state to well above the melting point allows us to observe temperature-dependent population levels and exchange between these two states. A simple physical picture emerges from this data, combined with published work, that provides a mechanism for hopping and for the Johari-Goldstein (β_{JG}) relaxation, and allows us to accurately calculate the diffusion coefficient, D_{T}, and characteristic times for α, and β_{JG} relaxations from ps time scale neutron data.

Optics Letters, 2004

Coherent anti-Stokes Raman scattering (CARS) microscopy is emerging as a powerful method for imag... more Coherent anti-Stokes Raman scattering (CARS) microscopy is emerging as a powerful method for imaging materials and biological systems, partly because of its noninvasiveness and selective chemical sensitivity. However, its full potential for species-selective imaging is limited by a restricted spectral bandwidth. Recent increases in bandwidth are promising but still are not sufficient for the level of robust component discrimination that would be needed in a chemically complex milieu found, for example, in intracellular and extracellular environments. We demonstrate a truly broadband CARS imaging instrument that we use to acquire hyperspectral images with vibrational spectra over a bandwidth of 2500 cm 21 with a resolution of 13 cm 21 .

European journal of pharmaceutics and biopharmaceutics : official journal of Arbeitsgemeinschaft für Pharmazeutische Verfahrenstechnik e.V, 2014

Lyophilized formulations of keratinocyte growth factor-2 (KGF-2) were prepared with a range of di... more Lyophilized formulations of keratinocyte growth factor-2 (KGF-2) were prepared with a range of disaccharide (sucrose or trehalose) and hydroxyethyl starch (HES) mass ratios. Protein degradation was assessed as a function of time of storage of the dried formulations at 40, 50 and 60°C. Lyophilized and stored samples were rehydrated, and protein degradation was quantified by measuring loss of monomeric protein with size exclusion chromatography and by determining chemical degradation in the soluble fraction with reverse-phase chromatography. The secondary structure of the protein in the lyophilized formulations was studied with infrared spectroscopy. The magnitudes of degradation were compared the key physical properties of the formulations including retention of protein native secondary structure, glass transition temperature (Tg), inverse mean square displacements 〈u(2)〉(-1) for hydrogen atoms (fast β relaxation), and the relaxation time τ(β), which correlates with relaxation due to...

Optics Letters, 2007

We demonstrate that a broadband coherent anti-Stokes Raman scattering (CARS) spectrum generated w... more We demonstrate that a broadband coherent anti-Stokes Raman scattering (CARS) spectrum generated with a typical two-pulse scheme contains two distinct, significant signals: "2-color" CARS, where the pump and probe are provided by a narrowband pulse and the continuum pulse constitutes the Stokes light, and "3color" CARS, where the pump and Stokes are provided by two different frequency components in the continuum pulse and the narrowband pulse serves as the probe. The CARS spectra from the two different mechanisms show distinct characteristics in Raman shift range, laser power dependence, and chirping dependence. We discuss the potential for a 3-color CARS signal to cover the fingerprint region with reduced photodamage of live cells. Official contribution of the National Institute of Standards and Technology; not subject to copyright in the United States.

Nature photonics

An imaging platform based on broadband coherent anti-Stokes Raman scattering (BCARS) has been dev... more An imaging platform based on broadband coherent anti-Stokes Raman scattering (BCARS) has been developed which provides an advantageous combination of speed, sensitivity and spectral breadth. The system utilizes a configuration of laser sources that probes the entire biologically-relevant Raman window (500 cm(-1) to 3500 cm(-1)) with high resolution (< 10 cm(-1)). It strongly and efficiently stimulates Raman transitions within the typically weak "fingerprint" region using intrapulse 3-colour excitation, and utilizes the nonresonant background (NRB) to heterodyne amplify weak Raman signals. We demonstrate high-speed chemical imaging in two- and three-dimensional views of healthy murine liver and pancreas tissues and interfaces between xenograft brain tumours and the surrounding healthy brain matter.

Tissue Engineering Part C: Methods, 2009

Two image-analysis approaches for pore size distribution (PSD) of porous media are proposed. The ... more Two image-analysis approaches for pore size distribution (PSD) of porous media are proposed. The methods are based on the skeleton representation of a porous object. One approach gives the local thickness of the pore object to represent the pore size corresponding to a lower limit of PSD. The other gives the pore size taking into account the anisotropy of pore object and corresponds to an upper limit of PSD. These two approaches can be incorporated into a computer program without computationally intensive and complex mathematical operations. In this study, these two approaches are applied to a two-dimensional (2D) synthetic image and 3D natural images of tissue scaffolds with various porosities and tortuosities. The scaffolds were prepared by removing the water-soluble poly(ethylene oxide) (PEO) component of the polycaprolactone (PCL)/PEO blend, leaving a porous PCL scaffold. Extracting quantitative PSD information for materials with an interconnected porous network rather than discrete voids (such as tissue scaffolds) is inevitably subjective without a universally accepted definition of &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;quot;pore size.&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;quot; Therefore, the proposed lower and upper limits of PSD can come into play when considering mass transfer and scaffold surface area for cell-matrix interaction.

The Journal of Physical Chemistry B, 1997

ABSTRACT

The Journal of Physical Chemistry B, 2008

Additives to polymeric materials can lead to appreciable changes in the rates of relaxation and r... more Additives to polymeric materials can lead to appreciable changes in the rates of relaxation and reaction in these mixtures that can profoundly alter material properties and function. We develop a general theoretical framework for quantifying changes in the "high-frequency" relaxation dynamics of mixtures based on classical transition state theory, in conjunction with mathematical statements regarding the dependence of the entropy (S + ) and enthalpy (E + ) of activation of the high-frequency relaxation time on diluent mass fraction, x w . Specifically, we deduce a general classification scheme for diluents based on a consideration of the sign of the differential change in S + and E + with x w . Two of these classes of diluents exhibit a transition from plasticization to antiplasticization (defined specifically as a speeding up or slowing down of relaxation relative to the pure system, respectively) upon varying temperature through an "antiplasticization" temperature, T anti . Extensive dielectric relaxation measurements on polycarbonate (PC) as a function of temperature and diluent (Aroclor) concentration are utilized to illustrate our theoretical model, and we focus particularly on the Arrhenius " " dielectric relaxation process of these mixtures. Many aspects of our scheme for quantifying changes in the high-frequency dynamics of mixtures are rationalized by our mixture model. In particular, we show that the dilution of PC by Aroclor is consistent with a theoretically predicted (one of the two antiplasticization mixture classes mentioned above) transition from antiplasticization to plasticization with decreasing temperature. We briefly compare our findings from dielectric measurements with those from elastic incoherent neutron scattering and dynamical-mechanical measurements, providing further evidence for the antiplasticizationto-plasticization transition phenomena that we observe in our high-frequency dielectric measurements.

Physical Review E, 2009

The structure, interactions, and interprotein configurations of the protein lysozyme were studied... more The structure, interactions, and interprotein configurations of the protein lysozyme were studied in a variety of phases. These properties have been studied under a variety of solution conditions before, during, and after freezing and after freeze-drying in the presence of glucose and trehalose. Contrast variation experiments have also been performed to determine which features of the scattering in the frozen solutions are from the protein and which are from the ice structure. Data from lysozyme at concentrations ranging from 1 to 100 mg/mL in solution and water ice with NaCl concentrations ranging from 0 to 0.4 mol/L are fit to model small-angle neutron scattering (SANS) intensity functions consisting of an ellipsoidal form factor and either a screened-Coulomb or hard-sphere structure factor. Parameters such as protein volume fraction and long dimension are followed as a function of temperature and salt concentration. The SANS results are compared to real space models of concentrated lysozyme solutions at the same volume fractions obtained from Monte Carlo simulations. A cartoon representation of the frozen lysozyme solution in 0 mol/L NaCl is presented based on the SANS and Monte Carlo results, along with those obtained from other complementary methods.

Optics Letters, 2009

We describe a closed-form approach for performing a Kramers-Kronig (KK) transform that can be use... more We describe a closed-form approach for performing a Kramers-Kronig (KK) transform that can be used to rapidly and reliably retrieve the phase, and thus the resonant imaginary component, from a broadband coherent anti-Stokes Raman scattering (CARS) spectrum with a nonflat background. In this approach we transform the frequency-domain data to the time domain, perform an operation that ensures a causality criterion is met, then transform back to the frequency domain. The fact that this method handles causality in the time domain allows us to conveniently account for spectrally varying nonresonant background from CARS as a response function with a finite rise time. A phase error accompanies KK transform of data with finite frequency range. In examples shown here, that phase error leads to small ͑Ͻ1%͒ errors in the retrieved resonant spectra.

Optics Express, 2009

We introduce a single-shot interferometric approach to suppress the nonresonant background (NRB) ... more We introduce a single-shot interferometric approach to suppress the nonresonant background (NRB) contribution to a broadband coherent anti-Stokes Raman scattering (CARS) spectrum; this single-shot approach is conducive to rapid imaging. A pulse shaper prepares a narrowband pulse with two spectral components of differing phase. When the CARS fields generated by these two out-of-phase components are optically mixed, NRB signal is greatly reduced while a resonant CARS signal remains with minimal attenuation. We discuss and demonstrate two model schemes for the interfering pulse components: (1) two pulses with different bandwidths and the same center frequency (ps-fs scheme) and (2) two pulses with the same bandwidth and shifted center frequencies (ps-ps scheme). In both schemes, only the resonant signal from the "3-color" CARS mechanism survives. The resonant signal from "2-color" CARS mechanism vanishes along with the NRB. We discuss optimization conditions for signal intensity and shape of resonant CARS peaks. Experimental CARS spectra of chexane and benzonitrile demonstrate feasibility of these approaches.

Optics Express, 2010

We demonstrate an optimization of continuum generation in a commercially available photonic cryst... more We demonstrate an optimization of continuum generation in a commercially available photonic crystal fiber and show that this continuum can be used to simultaneously measure vibrational dephasing times over an unprecedented frequency range of Raman modes. The dephasing time measurement is based on 2-pulse 3-color coherent anti-Stokes Raman scattering (CARS), and requires a continuum pulse that is coherent over a broad spectral bandwidth. We demonstrate that a continuum with the required characteristics can be generated from a photonic crystal fiber by appropriately conditioning the chirp of the excitation pulse and controlling its pulse energy. We are able to simultaneously measure vibrational dephasing times of multiple Raman modes (covering 500 cm −1 to 3100 cm −1 ) of acetonitrile and benzonitrile using the optimized continuum with broadband time-resolved CARS.

Optics Express, 2006

We introduce an interferometric technique for eliminating the non-resonant background of broadban... more We introduce an interferometric technique for eliminating the non-resonant background of broadband coherent anti-Stokes Raman scattering (CARS) microscopy. CARS microscopy has been used for imaging a number of biological samples and processes, but the studies are mostly limited to detecting lipids in biological systems by probing the C-H stretch. Non-resonant background and incoherent noise sources can easily overwhelm less intense signals from other molecular vibrations. In this study, we demonstrate a one-laser broadband interferometric technique that separates the spontaneous Raman scattering-related component of the CARS signal from the non-resonant background using liquid benzonitrile as a model system.

Macromolecules, 1995

ABSTRACT

Macromolecules, 1995

... Dynamics Marcus T. Cicerone, FR Blackburn, and MD Ediger* Department of Chemistry, University... more ... Dynamics Marcus T. Cicerone, FR Blackburn, and MD Ediger* Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706 Received July 18, 1995; Revised Manuscript Received September 14, 1995@ ...

While the structural basis of protein function is well understood in the biopharmaceutical and bi... more While the structural basis of protein function is well understood in the biopharmaceutical and biotechnology industries, few methods for the characterization and comparison of protein conformation distributions are available. New methods capable of measuring the stability of protein conformations and the integrity of protein-protein, protein-ligand and protein-surface interactions both in solution and on surfaces are needed to help the development

Coherent anti-Stokes Raman scattering (CARS) microscopy has exciting potential for rapid chemical... more Coherent anti-Stokes Raman scattering (CARS) microscopy has exciting potential for rapid chemical imaging of materials and noninvasive imaging of biological systems, both in-vivo, and as these systems interact with materials. Although CARS is as much as 10^6 times more sensitive that spontaneous Raman scattering, it is accompanied by a nonresonant background (NRB) signal which can mask the resonant signal of

Multiphoton Microscopy in the Biomedical Sciences IX, 2009

The Journal of Physical Chemistry, 1993

ABSTRACT

Molecular pharmaceutics, Jan 18, 2015

Nanosecond relaxation processes in sugar matrices are causally linked through diffusional process... more Nanosecond relaxation processes in sugar matrices are causally linked through diffusional processes to protein stability in lyophilized formulations. Long-term protein degradation rates track mean-squared displacement (⟨u(2)⟩) of hydrogen atoms in sugar glasses, a parameter describing dynamics on a time scale of picoseconds to nanoseconds. However, measurements of ⟨u(2)⟩ are usually performed by neutron scattering, which is not conducive to rapid formulation screening in early development. Here, we present a benchtop technique to derive a ⟨u(2)⟩ surrogate based on the fluorescence red edge effect. Glycerol, lyophilized trehalose, and lyophilized sucrose were used as model systems. Samples containing 10(-6) mole fraction of rhodamine 6G, a fluorophore, were excited at either 532 nm (main peak) or 566 nm (red edge), and the ⟨u(2)⟩ surrogate was determined based the corresponding Stokes shifts. Results showed reasonable agreement between ⟨u(2)⟩ from neutron scattering and the surrogate...

Physical review letters, Jan 12, 2014

We show that incoherent quasielastic neutron scattering from molecular liquids reveals a two-stat... more We show that incoherent quasielastic neutron scattering from molecular liquids reveals a two-state dynamic heterogeneity on a 1 ps time scale, where molecules are either highly confined or are free to undergo relatively large excursions. Data ranging from deep in the glassy state to well above the melting point allows us to observe temperature-dependent population levels and exchange between these two states. A simple physical picture emerges from this data, combined with published work, that provides a mechanism for hopping and for the Johari-Goldstein (β_{JG}) relaxation, and allows us to accurately calculate the diffusion coefficient, D_{T}, and characteristic times for α, and β_{JG} relaxations from ps time scale neutron data.

Optics Letters, 2004

Coherent anti-Stokes Raman scattering (CARS) microscopy is emerging as a powerful method for imag... more Coherent anti-Stokes Raman scattering (CARS) microscopy is emerging as a powerful method for imaging materials and biological systems, partly because of its noninvasiveness and selective chemical sensitivity. However, its full potential for species-selective imaging is limited by a restricted spectral bandwidth. Recent increases in bandwidth are promising but still are not sufficient for the level of robust component discrimination that would be needed in a chemically complex milieu found, for example, in intracellular and extracellular environments. We demonstrate a truly broadband CARS imaging instrument that we use to acquire hyperspectral images with vibrational spectra over a bandwidth of 2500 cm 21 with a resolution of 13 cm 21 .

European journal of pharmaceutics and biopharmaceutics : official journal of Arbeitsgemeinschaft für Pharmazeutische Verfahrenstechnik e.V, 2014

Lyophilized formulations of keratinocyte growth factor-2 (KGF-2) were prepared with a range of di... more Lyophilized formulations of keratinocyte growth factor-2 (KGF-2) were prepared with a range of disaccharide (sucrose or trehalose) and hydroxyethyl starch (HES) mass ratios. Protein degradation was assessed as a function of time of storage of the dried formulations at 40, 50 and 60°C. Lyophilized and stored samples were rehydrated, and protein degradation was quantified by measuring loss of monomeric protein with size exclusion chromatography and by determining chemical degradation in the soluble fraction with reverse-phase chromatography. The secondary structure of the protein in the lyophilized formulations was studied with infrared spectroscopy. The magnitudes of degradation were compared the key physical properties of the formulations including retention of protein native secondary structure, glass transition temperature (Tg), inverse mean square displacements 〈u(2)〉(-1) for hydrogen atoms (fast β relaxation), and the relaxation time τ(β), which correlates with relaxation due to...

Optics Letters, 2007

We demonstrate that a broadband coherent anti-Stokes Raman scattering (CARS) spectrum generated w... more We demonstrate that a broadband coherent anti-Stokes Raman scattering (CARS) spectrum generated with a typical two-pulse scheme contains two distinct, significant signals: "2-color" CARS, where the pump and probe are provided by a narrowband pulse and the continuum pulse constitutes the Stokes light, and "3color" CARS, where the pump and Stokes are provided by two different frequency components in the continuum pulse and the narrowband pulse serves as the probe. The CARS spectra from the two different mechanisms show distinct characteristics in Raman shift range, laser power dependence, and chirping dependence. We discuss the potential for a 3-color CARS signal to cover the fingerprint region with reduced photodamage of live cells. Official contribution of the National Institute of Standards and Technology; not subject to copyright in the United States.

Nature photonics

An imaging platform based on broadband coherent anti-Stokes Raman scattering (BCARS) has been dev... more An imaging platform based on broadband coherent anti-Stokes Raman scattering (BCARS) has been developed which provides an advantageous combination of speed, sensitivity and spectral breadth. The system utilizes a configuration of laser sources that probes the entire biologically-relevant Raman window (500 cm(-1) to 3500 cm(-1)) with high resolution (< 10 cm(-1)). It strongly and efficiently stimulates Raman transitions within the typically weak "fingerprint" region using intrapulse 3-colour excitation, and utilizes the nonresonant background (NRB) to heterodyne amplify weak Raman signals. We demonstrate high-speed chemical imaging in two- and three-dimensional views of healthy murine liver and pancreas tissues and interfaces between xenograft brain tumours and the surrounding healthy brain matter.

Tissue Engineering Part C: Methods, 2009

Two image-analysis approaches for pore size distribution (PSD) of porous media are proposed. The ... more Two image-analysis approaches for pore size distribution (PSD) of porous media are proposed. The methods are based on the skeleton representation of a porous object. One approach gives the local thickness of the pore object to represent the pore size corresponding to a lower limit of PSD. The other gives the pore size taking into account the anisotropy of pore object and corresponds to an upper limit of PSD. These two approaches can be incorporated into a computer program without computationally intensive and complex mathematical operations. In this study, these two approaches are applied to a two-dimensional (2D) synthetic image and 3D natural images of tissue scaffolds with various porosities and tortuosities. The scaffolds were prepared by removing the water-soluble poly(ethylene oxide) (PEO) component of the polycaprolactone (PCL)/PEO blend, leaving a porous PCL scaffold. Extracting quantitative PSD information for materials with an interconnected porous network rather than discrete voids (such as tissue scaffolds) is inevitably subjective without a universally accepted definition of &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;quot;pore size.&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;quot; Therefore, the proposed lower and upper limits of PSD can come into play when considering mass transfer and scaffold surface area for cell-matrix interaction.

The Journal of Physical Chemistry B, 1997

ABSTRACT

The Journal of Physical Chemistry B, 2008

Additives to polymeric materials can lead to appreciable changes in the rates of relaxation and r... more Additives to polymeric materials can lead to appreciable changes in the rates of relaxation and reaction in these mixtures that can profoundly alter material properties and function. We develop a general theoretical framework for quantifying changes in the "high-frequency" relaxation dynamics of mixtures based on classical transition state theory, in conjunction with mathematical statements regarding the dependence of the entropy (S + ) and enthalpy (E + ) of activation of the high-frequency relaxation time on diluent mass fraction, x w . Specifically, we deduce a general classification scheme for diluents based on a consideration of the sign of the differential change in S + and E + with x w . Two of these classes of diluents exhibit a transition from plasticization to antiplasticization (defined specifically as a speeding up or slowing down of relaxation relative to the pure system, respectively) upon varying temperature through an "antiplasticization" temperature, T anti . Extensive dielectric relaxation measurements on polycarbonate (PC) as a function of temperature and diluent (Aroclor) concentration are utilized to illustrate our theoretical model, and we focus particularly on the Arrhenius " " dielectric relaxation process of these mixtures. Many aspects of our scheme for quantifying changes in the high-frequency dynamics of mixtures are rationalized by our mixture model. In particular, we show that the dilution of PC by Aroclor is consistent with a theoretically predicted (one of the two antiplasticization mixture classes mentioned above) transition from antiplasticization to plasticization with decreasing temperature. We briefly compare our findings from dielectric measurements with those from elastic incoherent neutron scattering and dynamical-mechanical measurements, providing further evidence for the antiplasticizationto-plasticization transition phenomena that we observe in our high-frequency dielectric measurements.

Physical Review E, 2009

The structure, interactions, and interprotein configurations of the protein lysozyme were studied... more The structure, interactions, and interprotein configurations of the protein lysozyme were studied in a variety of phases. These properties have been studied under a variety of solution conditions before, during, and after freezing and after freeze-drying in the presence of glucose and trehalose. Contrast variation experiments have also been performed to determine which features of the scattering in the frozen solutions are from the protein and which are from the ice structure. Data from lysozyme at concentrations ranging from 1 to 100 mg/mL in solution and water ice with NaCl concentrations ranging from 0 to 0.4 mol/L are fit to model small-angle neutron scattering (SANS) intensity functions consisting of an ellipsoidal form factor and either a screened-Coulomb or hard-sphere structure factor. Parameters such as protein volume fraction and long dimension are followed as a function of temperature and salt concentration. The SANS results are compared to real space models of concentrated lysozyme solutions at the same volume fractions obtained from Monte Carlo simulations. A cartoon representation of the frozen lysozyme solution in 0 mol/L NaCl is presented based on the SANS and Monte Carlo results, along with those obtained from other complementary methods.

Optics Letters, 2009

We describe a closed-form approach for performing a Kramers-Kronig (KK) transform that can be use... more We describe a closed-form approach for performing a Kramers-Kronig (KK) transform that can be used to rapidly and reliably retrieve the phase, and thus the resonant imaginary component, from a broadband coherent anti-Stokes Raman scattering (CARS) spectrum with a nonflat background. In this approach we transform the frequency-domain data to the time domain, perform an operation that ensures a causality criterion is met, then transform back to the frequency domain. The fact that this method handles causality in the time domain allows us to conveniently account for spectrally varying nonresonant background from CARS as a response function with a finite rise time. A phase error accompanies KK transform of data with finite frequency range. In examples shown here, that phase error leads to small ͑Ͻ1%͒ errors in the retrieved resonant spectra.

Optics Express, 2009

We introduce a single-shot interferometric approach to suppress the nonresonant background (NRB) ... more We introduce a single-shot interferometric approach to suppress the nonresonant background (NRB) contribution to a broadband coherent anti-Stokes Raman scattering (CARS) spectrum; this single-shot approach is conducive to rapid imaging. A pulse shaper prepares a narrowband pulse with two spectral components of differing phase. When the CARS fields generated by these two out-of-phase components are optically mixed, NRB signal is greatly reduced while a resonant CARS signal remains with minimal attenuation. We discuss and demonstrate two model schemes for the interfering pulse components: (1) two pulses with different bandwidths and the same center frequency (ps-fs scheme) and (2) two pulses with the same bandwidth and shifted center frequencies (ps-ps scheme). In both schemes, only the resonant signal from the "3-color" CARS mechanism survives. The resonant signal from "2-color" CARS mechanism vanishes along with the NRB. We discuss optimization conditions for signal intensity and shape of resonant CARS peaks. Experimental CARS spectra of chexane and benzonitrile demonstrate feasibility of these approaches.

Optics Express, 2010

We demonstrate an optimization of continuum generation in a commercially available photonic cryst... more We demonstrate an optimization of continuum generation in a commercially available photonic crystal fiber and show that this continuum can be used to simultaneously measure vibrational dephasing times over an unprecedented frequency range of Raman modes. The dephasing time measurement is based on 2-pulse 3-color coherent anti-Stokes Raman scattering (CARS), and requires a continuum pulse that is coherent over a broad spectral bandwidth. We demonstrate that a continuum with the required characteristics can be generated from a photonic crystal fiber by appropriately conditioning the chirp of the excitation pulse and controlling its pulse energy. We are able to simultaneously measure vibrational dephasing times of multiple Raman modes (covering 500 cm −1 to 3100 cm −1 ) of acetonitrile and benzonitrile using the optimized continuum with broadband time-resolved CARS.

Optics Express, 2006

We introduce an interferometric technique for eliminating the non-resonant background of broadban... more We introduce an interferometric technique for eliminating the non-resonant background of broadband coherent anti-Stokes Raman scattering (CARS) microscopy. CARS microscopy has been used for imaging a number of biological samples and processes, but the studies are mostly limited to detecting lipids in biological systems by probing the C-H stretch. Non-resonant background and incoherent noise sources can easily overwhelm less intense signals from other molecular vibrations. In this study, we demonstrate a one-laser broadband interferometric technique that separates the spontaneous Raman scattering-related component of the CARS signal from the non-resonant background using liquid benzonitrile as a model system.

Macromolecules, 1995

ABSTRACT

Macromolecules, 1995

... Dynamics Marcus T. Cicerone, FR Blackburn, and MD Ediger* Department of Chemistry, University... more ... Dynamics Marcus T. Cicerone, FR Blackburn, and MD Ediger* Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706 Received July 18, 1995; Revised Manuscript Received September 14, 1995@ ...