We report a lipid‐based strategy to visualize Golgi structure and dynamics at super‐resolution in live cells. The method is based on two novel reagents: a trans‐cyclooctene‐containing ceramide lipid (Cer‐TCO) and a highly reactive, tetrazine‐tagged near‐IR dye (SiR‐Tz). These reagents assemble via an extremely rapid “tetrazine‐click” reaction into Cer‐SiR, a highly photostable “vital dye” that enables prolonged live‐cell imaging of the Golgi apparatus by 3D confocal and STED microscopy. Cer‐SiR is nontoxic at concentrations as high as 2 μM and does not perturb the mobility of Golgi‐resident enzymes or the traffic of cargo from the endoplasmic reticulum through the Golgi and to the plasma membrane. 相似文献
Poly(ethylene glycol)‐poly(lactide) (PEG‐PLA) block copolymers are processed to solvent cast films and solution electrospun meshes. The effect of polymer composition, architecture, and number of anchoring points for the plasticizer on swelling, degradation, and mechanical properties of these films and meshes is investigated as potential barrier device for the prevention of peritoneal adhesions. As a result, adequate properties are achieved for the massive films with a longer retention of the plasticizer PEG for star‐shaped block copolymers than for the linear triblock copolymers and consequently more endurable mechanical properties during degradation. For electrospun meshes fabricated using the same polymers, similar trends are observed, but with an earlier start of fragmentation and lower tensile strengths. To overcome the poor mechanical strengths and an occurring shrinkage during incubation, which may impair the coverage of the wound, further adaptions of the meshes and the fabrication process are necessary.
Matsuoka showed an asymptotic formula for the coefficients of the Laurent expansion of ζ (s) at s = 1. In the present paper we extend this result to a large class of Dirichlet series which was first studied by Chandrasekharan
and Narasimhan. Our proofs are based on a saddle point argument and use the fact that the Dirichlet series under consideration
admit a functional equation.
The second author was supported by the FWF project S381O. 相似文献
Structural deformations of lipid hybrid bilayer membranes induced by signal peptideless (SPL) proteins have been studied for the first time using the inherently surface specific nonlinear optical technique of sum frequency generation vibrational spectroscopy. Specifically, deformations of 1,2-distearoylphosphatidylglycerol(DSPG) membranes induced by interaction with FGF-1, a SPL protein which is released asa function of cellular stress through a nonclassical pathway, have been investigated. FGF-1 was found to induce lipid alkyl chain deformations in previously highly ordered DSPG membranes at the extremely low concentration of 1 nM at 60 degrees C. The deformation process was shown to exhibit a degree of reversibility upon removal of the protein by rinsing with buffer solution. 相似文献
The spin-selective photokinetics of a single matrix-isolated impurity molecule with a triplet-triplet optical transition, T0–T1, is considered and the manifestations of the photokinetics in the fluorescence excitation spectra and intensity autocorrelation functions g(2)(τ) of the molecule undergoing narrow-band optical excitation is studied to resolve the fine structure of the transition. The rates of intersystem crossings (ISCs) T1→S→T0 to and from a nonradiating singlet state S of the molecule and the rate of population relaxation among the ground (T0) state sublevels can be obtained from the spectra and g(2)(τ) using the analytical expressions obtained. New experiments on an individual NV defect center in nanocrystals of diamond, where, for the first time, the fine structure of its triplet-triplet 3A-3E zero-phonon optical transition (~637 nm) at 1.4 K was resolved, are interpreted. It is concluded that the rate of the ISC transition from the mS=0 sublevel of the excited 3E state to the singlet 1A state (~1 kHz) is much slower than the rates from the mS=±1 substates, while the rates of ISC transitions to different mS substates of the ground 3A state are close to each other (~1 Hz). As a result, only the optical transition between mS=0 sublevels in the 3A-3E manifold contributes strongly to the fluorescence. The experimentally observed double-exponential decay of the g(2)(τ) function is explained by the two pathways available to the center for it to leave the S state: (i) the S→ T0(mS)=0) transition and (ii) the S→T0(mS=±1) transitions followed by the slow spin-lattice relaxation T0(mS=±1)→T0(mS=0) (rate ~0.1 Hz). The work is important for studies where the NV center is used as a single photon source or for quantum information processing. 相似文献
We investigate electrical transport and noise in semiconducting carbon nanotubes. By studying carbon nanotube devices with various diameters and contact metals, we show that the ON-currents of CNFETs are governed by the heights of the Schottky barriers at the metal/nanotube interfaces. The current fluctuations are dominated by 1/f noise at low-frequencies and correlate with the number of transport carriers in the device regardless of contact metal. 相似文献
After the synthesis and isolation of methylated bismuth cysteine, its initial identification by IR-spectroscopy was performed,
whereas for definitive identification, high resolution mass spectrometry (ESI-TOF-MS and LTQ Orbitrap) was carried out. 相似文献