Preparation of the particles of Acanthopanax senticosus

The main objective of this study is to establish the best preparation technology of the particles of Acanthopanax senticosus. First, take the reflux extraction method extract of Acanthopanax senticosus coarse powder, optimized by orthogonal experimental method, to flavonoids flavonoids extraction extraction rate as the indexes to determine the effects of extraction temperature, ethanol concentration, extraction time on flavonoids content. Then by a wet granulation of thorn slender acanthopanax particles, taste with granules, forming rate, melting rate as index to investigate the influences of materials adding amount of granules effect. The results showed that the ethanol water heating reflux extraction method to extract the temperature of 70 deg, the percentage of ethanol 75%, extraction time 2.5 h, the highest content of total flavonoids in the extract. Join the 5 ml and 10 g in the extract of acacia honey, dextrin, starch, sugar ratio for 3:4:8, the best taste of Acanthopanax granules. In the end, the best preparation technology of the granules is established, and the process is simple, which is suitable for the large-scale production of the factory.     

On the three-dimensional reconstruction of icosahedral particles

The problem of reconstructing an isolated particle from its projections, using spherical harmonics to represent the scattering density, is reformulated. A technique that makes explicit and efficient use of the symmetry to describe the angular part of the scattering density is developed in full detail for the particular case of icosahedral symmetry. It provides a very concise method, where the effort is concentrated in the determination of the radial part of the Fourier transform of the particle scattering density. The method allows individual-image model-independent view determination. An illustrative numerical example is given.     

Challenges for the production of virus-like particles in insect cells: The case of rotavirus-like particles

Virus-like particles (VLP) are formed when viral structural proteins are produced in an heterologous expression system. Such proteins assemble into structures that are morphologically similar to native viruses but lack the viral genome. VLP are complex structures with a wide variety of applications, ranging from basic research and vaccines to potential new uses in nanotechnology. Production of VLP is a challenging task, as both the synthesis and assembly of one or more recombinant proteins are required. This is the case for VLP of rotavirus (RLP), which is an RNA virus with a capsid formed by 1860 monomers of four different proteins. In addition, the production of most VLP requires the simultaneous expression and assembly of several recombinant proteins, which – for the case of RLP – needs to occur in a single host cell. The insect cell baculovirus expression vector system (IC-BEVS) has been shown to be a powerful and convenient system for rapidly and easily producing VLP, due to several convenient features, including its versatility and the short time needed for construction of recombinant baculovirus. In this review, the specific case of rotavirus-like particle (RLP) production by the IC-BEVS is discussed, with emphasis on bioprocess engineering issues that exist and their solutions. Many culture strategies discussed here can be useful for the production of other VLP.     

hnRNP particles

This article describes the discovery of nuclear DNA-like RNA (dRNA or hnRNA) and ribonucleoprotein particles in eukaryotes. Native hnRNA particles were isolated by sucrose gradient sedimentation and their structural organisation – nucleic acid (i.e. RNA) wrapped in a regular way on the surface of a series of globular protein particles – was determined. This led to the formulation of the informofer cycle hypothesis for the synthesis of hnRNA as a giant precursor molecule, its transport in informosomes within the nucleus, and subsequent splicing before export from the nucleus as free mRNA.     

Virus-like particles in the brown algaStreblonema

Summary Ultrastructural examination ofStreblonema sp. revealed icosahedral virus-like particles (135–150 nm) throughout the cytoplasm of vegetative cells. The densely packed particles consist of an osmiophilic coat around a fibrillar core. Most cytoplasmic organelles are excluded from the regions where the particles are extremely abundant, but no degeneration of plastids, mitochondria or dictyosomes is evident. The virogenic stroma contains many ribosomes and fibers possibly representing DNA strands remaining from the lysed nucleus. No decrease in vigor seemed to be associated with the presence of the particles.     

Measurement of the nucleation of atmospheric aerosol particles

The formation of new atmospheric aerosol particles and their subsequent growth have been observed frequently at various locations all over the world. The atmospheric nucleation rate (or formation rate) and growth rate (GR) are key parameters to characterize the phenomenon. Recent progress in measurement techniques enables us to measure atmospheric nucleation at the size (mobility diameter) of 1.5 (±0.4) nm. The detection limit has decreased from 3 to 1 nm within the past 10 years. In this protocol, we describe the procedures for identifying new-particle-formation (NPF) events, and for determining the nucleation, formation and growth rates during such events under atmospheric conditions. We describe the present instrumentation, best practices and other tools used to investigate atmospheric nucleation and NPF at a certain mobility diameter (1.5, 2.0 or 3.0 nm). The key instruments comprise devices capable of measuring the number concentration of the formed nanoparticles and their size, such as a suite of modern condensation particle counters (CPCs) and air ion spectrometers, and devices for characterizing the pre-existing particle number concentration distribution, such as a differential mobility particle sizer (DMPS). We also discuss the reliability of the methods used and requirements for proper measurements and data analysis. The time scale for realizing this procedure is 1 year.