抗原变异可使得多种致病微生物易于逃避宿主免疫应答。表达在感染红细胞表面的恶性疟原虫红细胞表面蛋白1（PfPMP1）与感染红细胞、内皮细胞、树突状细胞以及胎盘的单个或多个受体作用，在黏附及免疫逃避中起关键的作用。每个单倍体基因组var基因家族编码约60种成员，通过启动转录不同的var基因变异体为抗原变异提供了分子基础。

疟原虫var基因转换速率变化导致抗原变异[英]／Paul H, Robert P, Christodoulou Z, et al//Proc Natl Acad Sci U S A

https://pubs.rsc.org/en/content/articlepdf/2019/NP/C8NP00092A

Marine natural products.

N G van Kampen 1981 Amsterdam: North-Holland xiv + 419 pp price Dfl 180 This is a book which, at a lower price, could be expected to become an essential part of the library of every physical scientist concerned with problems involving fluctuations and stochastic processes, as well as those who just enjoy a beautifully written book. It provides an extensive graduate-level introduction which is clear, cautious, interesting and readable.

https://iopscience.iop.org/article/10.1088/0031-9112/34/4/040/pdf

Stochastic Processes in Physics and Chemistry

Confocal microscopy was used to directly observe three-dimensional dynamics of particles in colloidal supercooled fluids and colloidal glasses. The fastest particles moved cooperatively; connected clusters of these mobile particles could be identified; and the cluster size distribution, structure, and dynamics were investigated. The characteristic cluster size grew markedly in the supercooled fluid as the glass transition was approached, in agreement with computer simulations; at the glass transition, however, there was a sudden drop in their size. The clusters of fast-moving particles were largest near the α-relaxation time scale for supercooled colloidal fluids, but were also present, albeit with a markedly different nature, at shorter β-relaxation time scales, in both supercooled fluid and glass colloidal phases.

http://science.sciencemag.org/content/sci/287/5453/627.full.pdf

Three-Dimensional Direct Imaging of Structural Relaxation Near the Colloidal Glass Transition

Hypertension 66 (20.3%) 24 (24.2%) 30 (16.3%) NS Diabetes 20 (6.2%) 7 (7.1%) 10 (5.4%) NS Excess weight 78 (24%) 27 (27.3%) 44 (23.9%) NS Smokers 64 (19.7%) 17 (17.2%) 35 (19.0%) NS Age >50 years 137 (42.2%) 54 (54.5%) 67 (36.4%) <0.02 Kidney disease 7 (2.2%) 1 (1%) 5 (2.7%) NS Family history, DM 102 (31.4%) 28 (28.3%) 66 (35.9%) NS

Conflict of interest statement. None declared.

We present a robust and high signal-to-noise strategy for phase-selective ultrafast electronic coherence spectroscopy. We demonstrate our approach using atomic Rb, isolating specific non-linear signal contributions to the excited state population.

Fluorescence-detected two-dimensional electronic coherence spectroscopy by acousto-optic phase modulation

Jaspamide, a modified peptide from a Jaspis sponge, with insecticidal and antifungal activity.

Time-resolved fluorescence anisotropies of two ionic lipophilic probes, merocyanine 540 and octadecylrhodamine B, in alcohol solvents and in sodium dodecyl sulfate, dodecyltrimethylammonium bromide, and Triton X-100 micelles were measured using time-correlated single-photon counting. In alcohols, the anisotropy decays were single exponentials. In micelles, the anisotropy decays were biexponential, corresponding to a short and a long rotational correlation time. The results are interpreted in terms of a two-step model consisting of fast restricted rotation of the probe and slow lateral diffusion of the probe in the micelle. The decrease in the residual anisotropy is caused mainly by lateral diffusion of the probe in the micelle. Information about the restricted rotation of the probe is obtained by using the parameters in the biexponential fit to calculate cone angles and wobbling diffusion constants for the wobbling-in-cone model. Lateral diffusion constants are also determined. 68 refs., 5 figs., 4 tabs.

/pdf/dynamics-of-ionic-lipophilic-probes-in-micelles-picosecond-3ai64l0uba.pdf

Dynamics of ionic lipophilic probes in micelles: Picosecond fluorescence depolarization measurements

Two-dimensional photocurrent spectroscopy can identify coherent electronic dynamics and offers promise for studies of numerous material systems. Karki et al. now show that the method can be used to study ultrafast carrier processes in lead sulphide quantum dots, such as multiple exciton generation.

/pdf/coherent-two-dimensional-photocurrent-spectroscopy-in-a-pbs-505rid33fv.pdf

Coherent two-dimensional photocurrent spectroscopy in a PbS quantum dot photocell

We report, from direct observation of particle trajectories as a function of time, the presence of stringlike cooperative motion in a quasi-two-dimensional liquid. We have used digital video microscopy to study the equilibrium dynamics of suspensions of sterically stabilized uncharged poly(methylmethacrylate) spheres confined in a thin glass cell. Our experiments reveal the existence, in semidilute and dense liquid states, of a transition in the qualitative dynamical behavior of the system. At short times particles undergo unhindered Brownian motion, at intermediate times they undergo uncorrelated binary collisions, and at long times these one-particle self-diffusive modes are coupled to collective longitudinal acoustic modes of the fluid, the signature of which is local fluctuating domains of enhanced particle mobility. We study the properties of these domains by examining the density dependence of the van Hove self-correlation function and its deviation from Gaussian behavior. We observe that periods of non-Gaussian behavior correlate precisely with the timing of events involved in the relaxation of "caged" particles and their nearest neighbors. In contrast with relaxation processes in supercooled liquids, the lifetime of dynamical heterogeneities in a dissipative colloidal suspension is found to shift towards shorter time scales with increasing particle density. During time periods for which a quasi-two-dimensional system follows Gaussian behavior, we observe that, as predicted by Cichocki and Felderhof [J. Phys. Condens. Matter 6, 7287 (1994)], the time dependence of the evolution of the effective diffusion coefficient from its short time to its long time value has the form (ln t)/t. This last finding is true for all observed particle densities. To our knowledge, these results are the first experimental verification of the existence of microscopic cooperativity and the predicted temporal evolution of the diffusion coefficient for Brownian motion in concentrated quasi-two-dimensional liquids.

Andrew H. Marcus

Papers

Fluorescence-detected two-dimensional electronic coherence spectroscopy by acousto-optic phase modulation

Jaspamide, a modified peptide from a Jaspis sponge, with insecticidal and antifungal activity.

Dynamics of ionic lipophilic probes in micelles: Picosecond fluorescence depolarization measurements

Coherent two-dimensional photocurrent spectroscopy in a PbS quantum dot photocell

Experimental observations of non-Gaussian behavior and stringlike cooperative dynamics in concentrated quasi-two-dimensional colloidal liquids.