Ekspla CARS 相干反斯托克斯拉曼显微光谱仪

In numerous applications in microfluidics, cell growth, soft lithography, and molecular imprinting, the surface of poly(dimethylsiloxane) (PDMS) is modified from a hydrophobic methyl-terminated surface to a hydrophilic hydroxylterminated surface. In this study, we investigated molecular structural and orientational changes at the PDMS-air interface in response to three commonly used surface modification processes: exposure to long-wavelength ultraviolet light (UV), exposure to short-wavelength UV that generates ozone (UVO), and exposure to oxygen plasma (OP). The surfaces of two PDMS compositions (10:1 and 4:1 of base polymer/curing agent) were probed during modification, using monolayer-sensitive IR + visible sum frequency generation (SFG) vibrational spectroscopy, with two different polarization combinations. During PDMS surface modification, the peak intensities of CH3 side groups and CH2 cross-link groups decreased, while peak intensities of Si-OH groups increased. There was no significant change in the average orientation of the CH3 groups on the PDMS surface during modification. The concentration of CH3 groups on the surface decreased exponentially with time, for all three UV, UVO, and OP modification processes, with first order kinetics and time constants of approximately 160, 66, and 0.3 min, respectively. At steady state, residual CH3 groups were detected at the PDMS surface for UV and UVO treatments; however, there were negligible CH3 groups detected after OP modification.

We present a direct comparison of phase sensitive sum-frequency generation experiments with phase reconstruction obtained by the maximum entropy method. We show that both methods lead to the same complex spectrum. Furthermore, we discuss the strengths and weaknesses of each of these methods, analyzing possible sources of experimental and analytical errors. A simulation program for maximum entropy phase reconstruction is available at: http://lbp.epfl.ch/.

he nature of water's hydrogen-bonding network is a vital in fluence on the chemistry that occurs at interfaces, but a complete understanding of interfacial water has proven elusive. Even-order nonlinear optical spectroscopies, such as vibrational sum frequency generation (VSFG) spectroscopy and heterodyne detected phase-sensitive sum frequency generation (PS-SFG) spectroscopy, are inherently surface specific. With the advent of advances in these spectroscopic techniques, researchers can now explore many longstanding questions about the dynamics and structures present at the vapor
water and water
solid interfaces. Of special interest to the atmospheric chemistry community is the accommodation of ions and solutes by water's hydrogen-bonding network. A better understanding of how ions and solutes behave in hydrogen-bonded water has afforded a fresh perspective of aqueous aerosols, because the interactions involved therein drive phenomena such as the hydrolysis of atmospheric chemical species. In this Account, we present work from our laboratory focusing on applying VSFG and the recently developed PSSFG techniques to probe the perturbation ofwater's hydrogen-bonding network at the vapor
water interface by a variety of ions and solutes. We also present very recent results from our laboratory on the direct observation of the adsorption of ions at the water
CaF2 interface.

Recent advances in the performance of organic semiconductors such as organic light emitting diodes (OLEDs), organic field-effect transistors (OFETs), and organic solar cells have been dramatic. In particular for OLEDs, stability and durability have improved to levels that warrant their application in everyday life. In organic devices, the charge carriers, both electrons and holes, often have to be injected through organic/electrode interfaces. Therefore, an understanding of the interaction between metal electrode and organic molecules is quite important, because the electronic properties of metal/organic interface directly affect the performance of the OLEDs.

The molecular origins of second-order nonlinear effects in type I collagen fibrils have been identified with sumfrequency generation vibrational spectroscopy. The dominant contributing molecular groups are: 1), the methylene groups associated with a Fermi resonance between the fundamental symmetric stretch and the bending overtone of methylene; and 2), the carbonyl and peptide groups associated with the amide I band. The noncentrosymmetrically aligned methylene groups are characterized by a distinctive tilt relative to the axis perpendicular to the main axis of the collagen fiber, a conformation producing a strong achiral contribution to the second-order nonlinear effect. In contrast, the stretching vibration of the carbonyl groups associated with the amide I band results in a strong chiral contribution to the optical second-order nonlinear effect. The length scale of these chiral effects ranges from the molecular to the supramolecular.

采用ATRP 技术合成了不同含氟段长度的聚甲基丙烯酸甲酯-b-聚(甲基丙 烯酸-2-全氟辛基乙酯)(PMMA144-b-PFMAn)嵌段共聚物. 利用接触角、XPS、SFG、 表面张力、DLS 等技术研究了不同含氟段长度PMMA144-b-PFMAn 溶液气/液界面性 质、聚合物分子在溶液中的聚集行为与其固化后表面结构与性能. 发现含少数几个 氟化结构单元的嵌段共聚物就呈现出优异的疏水疏油性. 含氟段的增长其表面性能 反而下降. 对其表面结构进行研究发现, 含氟量的增加, 使含氟组分在表面富集程 度的增加有限, F/C 比则随深度的增加而增加. 同时全氟烷基在表面的排列有序性下 降. 当氟化结构单元的长度为10 时, 共聚物的表面层反而出现了PMMA 的链段. 原 因主要是由于含氟段的长度影响嵌段共聚物分子在溶液中的聚集结构和气/液界面 结构, 从而影响固化过程中其表面结构的形成. 结果表明, 高含氟量的聚合物不一 定具有优异的表面性能, 合适的溶液性质对含氟聚合物表面结构的形成具有重要的 影响.

For dense sprays such as those encountered in diesel or gasoline direct injection, the interpretation of spray images is complicated by the fact that most of the light reaches the detectors after multiple scattering events within the spray. This may introduce severe errors when extracting quantitative or even qualitative information from these images as many diagnostics rely on the assumption of single photon scattering. It has recently been shown that the multiple scattering component of spray images can be effectively suppressed if sets of structured light sheets are used to illuminate the spray. The aim of this report is to illustrate the potential and the limitations of this technique for the visualization of sprays from modern diesel and gasoline injectors at elevated atmospheric pressures. The results clearly show that conventionally recorded images are dominated by multiple scattering, causing the light sheet to widen substantially and obscuring details within the light sheet plane. In contrast, multiple scattering and indirect reflections can be suppressed using structured light sheets and proper image processing. Careful interpretation of the corresponding images reveals details of the inner spray structure and thus contributes to the understanding of the complicated spray break-up and atomization processes.

The test rig employed in this study consisted of a high-pressure cylindrical steel vessel with a length of 1.8 m and an internal diameter of 0.28 m. Visual inspection and accessibility of the reactor assembly was achieved via a 50 mm diameter quartz window at the rear flange of the vessel and two 350 mm long and 50 mm high quartz windows at the vessel sides. The test setup (Fig. 2.1) consisted of a channelflow catalytic reactor, which was mounted inside the high-pressure cylindrical vessel. The reactor comprised two horizontal Si[SiC] plates with a length (x) of 300 mm, width (z) of 104 mm and thickness of 9 mm; the plates were positioned 7 mm apart (y). The other two sides of the reactor were formed by two 3-mm-thick vertical quartz windows.

A high level of fluorescence background signal rejection was achieved for solid and powder samples by using a combination of simple low-resolution spectrograph and ultrafast gated charge coupled device ~CCD! camera. The unique timing characteristics of the CCD camera match exceptionally well to characteristics of a Ti:sapphire oscillator allowing fast gated light detection at a repetition rate of up to 110 MHz, making this approach superior in terms of the duty cycle in comparison with other time-resolved Raman techniques. The achieved temporal resolution was about 150 ps under 785 nm Ti: sapphire laser excitation. At an average excitation power up to 300 mW there was no noticeable sample damage observed. Hence, the demonstrated approach extends the capabilities of Raman spectroscopy regarding the investigation of samples with a short fluorescence lifetime. The combination of a spectrometer and a gated CCD camera allows simultaneous study of spectral and temporal characteristics of emitted light. This capability opens an exciting possibility to build a universal instrument for solving multitask problems in applied laser spectroscopy

In this work multimodal operation of commercially available CARS microspectrometer (EKSPLA CARSCOPE) equipped with a picosecond dual wavelength laser source (EKSPLA PT259) was demonstrated for the imaging of various biological objects using coherent anti‑Stokes Raman scattering (CARS), two photon excited fluorescence (TPEF) and second harmonic generation (SHG) contrast mechanisms. Obtained CARS‑images of yeast cell and flower pollen clearly demonstrate label‑free and 3D imaging capabilities of CARS technique. Multi‑contrast images of green algae and plants containing starch demonstrate a variety of research facilities, where the method can be applied.

Electrostatic, rotating bell (ESRB) application is one of the most important coating application techniques for industries with demanding specifications for optical attractiveness of coatings, such as automotive. The ESRB process involves production of droplets using a high-speed rotating bell, which are subsequently transported to the substrate being coated via shaping air [1-3]. An electrical potential is applied between the bell and the substrate which further helps droplet atomization and transport. This research investigates the effects of inertia, centrifugal force, drag force, and electrostatic force on the atomization mechanism and particle size distribution using an automotive OEM base coat formulation. Coating flow rate (CFR), shaping air flow rate (SAFR), bell speed (BS), and electrostatic potential (EP) were used as primary parameters to create various atomization conditions and particle size distributions. The atomization mechanism, ligament formation, and particle size distribution were measured using high-speed laser shadowography and image processing. The effects of governing forces and particle size generated on efficiency of droplet transfer to the substrate and optical appearance of the coatings were studied to generate operating windows for optimum process efficiency and appearance.

NADPH oxidase (NOX2) is a multisubunit membrane-bound enzyme complex that, upon assembly in activated cells, catalyses the reduction of free oxygen to its superoxide anion, which further leads to reactive oxygen species (ROS) that are toxic to invading pathogens, for example, the fungus Aspergillus fumigatus. Polymorphonuclear cells (PMNs) employ both nonoxidative and oxidative mechanisms to clear this fungus from the lung. The oxidative mechanisms mainly depend on the proper assembly and function of NOX2. We identified for the first time the NAD(P)H-dependent enzymes involved in such oxidative mechanisms by means of biexponentialNAD(P)H-fluorescence lifetime imaging (FLIM). A specific fluorescence lifetime of 3670±140 picoseconds as compared to 1870 picoseconds for NAD(P)H bound to mitochondrial enzymes could be associated with NADPH bound to oxidative enzymes in activated PMNs. Due to its predominance in PMNs and due to the use of selective activators and inhibitors, we strongly believe that this specific lifetime mainly originates from NOX2. Our experiments also revealed the high site specificity of the NOX2 assembly and, thus, of the ROS production as well as the dynamic nature of these phenomena. On the example of NADPH oxidase, we demonstrate the potential of NAD(P)H-based FLIM in selectively investigating enzymes during their cellular function.

Various types of capacitively coupled radio frequency (CCRF) discharges are frequently used for different applications ranging from chip and solar cell manufacturing to the creation of biocompatible surfaces. In many of these discharges electron heating and electron dynamics are not fully understood. A powerful diagnostic to study electron dynamics in CCRF discharges is phase resolved optical emission spectroscopy (PROES). It is non-intrusive and provides access to the dynamics of highly energetic electrons, which sustain the discharge via ionization, with high spatial and temporal resolution within the RF period. Based on a time dependent model of the excitation dynamics of specifically chosen rare gas levels PROES provides access to plasma parameters such as the electron temperature, electron density and electron energy distribution function (EEDF). In this work the method of PROES is reviewed and some examples of its application are discussed. First, the generation of highly energetic electron beams by the expanding sheath in geometrically symmetric as well as asymmetric discharges and their effect on the EEDF are investigated. Second, the physical nature of the frequency coupling in dual frequency discharges operated at substantially different frequencies is discussed. Third, the generation of electric field reversals during sheath collapse in single and dual frequency discharges is analysed. Then excitation dynamics in an electrically asymmetric novel type of dual frequency discharge is studied. Finally, limitations of PROES are discussed.

Amphiphysin 1, an endocytic adaptor concentrated at synapses that couples clathrin-mediated endocytosis to dynamin-dependent fission,wasalsoshownto have a regulatory role in actindynamics. Here, we report that amphiphysin 1 interacts with N-WASP and stimulates N-WASP- and Arp2/3-dependent actin polymerization. Both the Src homology 3 and the N-BAR domains are requiredforthisstimulation.Acidicliposome-triggered,N-WASPdependent actin polymerization is strongly impaired in brain cytosol of amphiphysin 1 knock-out mice. FRET-FLIM analysis of Sertoli cells, where endogenously expressed amphiphysin 1 colocalizes with N-WASP in peripheral ruffles, confirmed the association between the two proteins in vivo. This association undergoes regulation and is enhanced by stimulating phosphatidylserine receptors on the cell surface with phosphatidylserine- containing liposomes that trigger ruffle formation. These results indicate that actin regulation is a key function of amphiphysin 1 and that such function cooperates with the endocytic adaptor role and membrane shaping/curvature sensing properties of the protein during the endocytic reaction.