Efficient and Selective Catalytic Conversion of Hemicellulose in Rice Straw by Metal Catalyst under Mild Conditions

Rice straw is an abundant material with the potential to be converted into a sustainable energy resource. Transition-metal catalysis activated the C–O bond in the hemicellulose of raw rice straw, cleaving it to form monosaccharides. The mechanism of rice straw catalytic conversion had a synergistic effect due to in situ acid catalysis and metal catalysis. The conditions for the hydrogenation of hemicellulose from rice straw were optimized: catalyst to rice straw solid/solid ratio of 3:10, stirring speed of 600 r/min, temperature of 160 °C, time of 3 h, solid/liquid ratio of 1:15, and H2 gas pressure of 1.5 MPa. An excellent hemicellulose conversion of 97.3% with the yields of xylose and arabinose at 53.0% and 17.3%, respectively, were obtained. The results from FTIR and SEM experiments also confirmed the destruction of the rigidity and reticulate structure of rice straw after the catalytic reaction.

Sperm ultrastructure in the ocean quahog Arctica islandica (Arcticidae) and Neotrapezium sublaevigatum (Trapezidae), with a discussion of relationships within the Arcticoidea and with other Euheterodonta (Bivalvia)

ABSTRACT Sperm ultrastructure is described for the ocean quahog Arctica islandica (Linnaeus, 1767) (Arcticidae), a long-lived, and commercially and phylogenetically important marine bivalve from the North Atlantic, and for Neotrapezium sublaevigatum (Lamarck, 1819), an Indo-Pacific member of the only other family of Arcticoidea (Trapezidae). Spermatozoa of A. islandica consist of (in anterior to posterior sequence): an elongate-conical, deeply invaginated, acrosomal vesicle (length 2.0 ± 0.2 μm; invagination occupied by a granular subacrosomal material); a straight, anteriorly-tapered, rod-shaped nucleus (length 6.6 ± 0.4 μm); a short (approximately 0.8 μm) midpiece consisting of two orthogonally arranged centrioles, surrounded by four (approximately 75% of spermatozoa observed) or, less commonly, five (approximately 25% of spermatozoa observed) spherical mitochondria; nine satellite fibres connecting the distal centriole to mitochondria and the plasma membrane; and a flagellum (length 60 ± 5.0 μm, with 9+2 axoneme), originating from the distal centriole. Contents of the acrosomal vesicle of A. islandica are differentiated into a very electron-dense basal ring (with reticulate structure) and two less electron-dense zones. Spermatozoa of N. laevigatum (Lamarck, 1819) differ substantially from those of A. islandica and are characterized by: a rounded-conical, deeply invaginated, acrosomal vesicle (length 0.43 ± 0.2 μm), with a curved basal ring and two less conspicuous components; a barrel-shaped nucleus (length 1.6 ± 0.5 μm) with a broad apical depression accommodating the base of the acrosomal vesicle; a midpiece composed of five (approximately 80% of spermatozoa observed) or four (approximately 20% of spermatozoa observed) mitochondria. Centriolar and flagellar details are essentially as for A. islandica, and putative glycogen deposits are associated with the distal centriole and mitochondria in both species. Sperm data corroborate recent transcriptomic analyses separating Arcticidae and Trapezidae in different imparidentian clades. Based on sperm morphology, A. islandica would appear more closely related to the Glauconomidae of the Cyrenoidea than to the Trapezidae, Veneroidea or any other previously examined group of euheterodonts, suggesting that it could be the only living member of the Arcticoidea. The relationships of the Trapezidae remain uncertain, with apparent sperm similarities to members of several groups of euheterodonts (e.g. Tellinoidea, Pholadoidea, Galeommatoidea), while several potentially closely related key taxa (e.g. Glossidae) remain unstudied for sperm characters.

Micromorphology of an involucral bract and cypselae of the endemic and relict species Amphoricarpos elegans Albov (Asteraceae, Cardueae) from the Caucasus

In this study, micromorphology of an involucral bract and inner and outer dimorphic cypselae of the relict Amphoricarpos elegans, endemic from western Caucasus, is examined using a scanning electron microscope (SEM) and presented here for the first time. The middle involucral bract is nearly glabrous, with a reticulate-rugulose surface and an oblong-obtusate mucro. Both cypselae exhibit similar features, viz., narrowly oblong-cylindrical or obovate shape with more or less conspicuous longitudinal ribs, an adaxial detachment area, an asymmetrical carpopodium, absence of a pericarp crown and a barbate-aristate pappus made up of narrow, subulate, basally smooth and apically barbate bristles. However, some differences are evident. The outer cypsela is glabrescent and flattened, with an obscure outline of epidermal cells lacking an end wall and with a sunken periclinal surface and striatereticulate structure. Also, the outer cypsela has two entire, narrow, lateral wings, rounded above; and less numerous pappus bristles in one row. In contrast to this, the inner cypsela has a distinct outline of the epidermal cells, which are rod-shaped with a short acute end wall, a swollen periclinal surface and reticulate structure. The pappus of the inner cypsela possesses many more bristles organised in two rows (a biseriate pappus). Also, slightly pentagonal or round nectary remnants are found in the centre of the upper part of the inner cypsela. The taxonomic value of the analysed characters is briefly discussed.

MICROSTRUCTURAL ANALYSIS OF FORCEMEATS OF READY-TO-COOK CHOPPED MEAT WITH FUNCTIONAL INGREDIENTS

Meat products, at different technological stages and as finished articles, retain their morphological features. Microstructure analysis of the raw material, ready-to-cook products, or finished articles allows determining the presence of certain types of tissues, organs, spices – and low-value admixtures the recipe does not provide for, as well as reused raw materials. Microstructural studies of ready-to-cook chopped meat products allows identifying their components, establishing different properties of various tissue and cellular structures, and controlling the articles manufactured. Minced beef as the object of research was modified, with 5 %, 10 %, 15 % of the meat part replaced with lupin flour and 0.5% of elecampane root powder added as aromatic raw material. For microscopic examination, samples of the forcemeats developed were put marks on and fixed in a 10 % neutral formalin solution. The sections, as thick as 0.5–1 cm, were cut on a sledge microtome. They were stained with haematoxylin and eosin, and the PAS reaction. Light microscopy and microphotography of the tissue specimens were performed with a microscope Leica DM 2500 and a camera Leica DFC 450C with the software Leica aplitation suite 4.4. The micrographic investigation of the forcemeats revealed polygonal and round muscle fibres (their dark nuclei were clearly seen under the sarcolemma), concentrations of adipose tissue histologically characterized by a reticulate structure. In the microphotographs, lupin flour looks like groups of round light purple cytoplasm with dark purple nuclei in the centre of polygonal cells; bread looks like loose brown fibres; wavy violet fibres represent onions; and single dark brown spots marked elecampane. It has been shown that histological studies, with the PAS reaction used, are helpful in determining the meat and plant content in the ready-to-cook meat developed, and that haematoxylin and eosin can help determine the functional ingredients content.

Preparation and Analyzing Character of Chitosan Block in Fluffy Meshwork Shape Formed from Chitosan Fine Hair

Depending on available theory and literature about chitosan (CS), the paper studied the method of preparation of CS block in fluffy meshwork shape with fine hair shape and analysis its structure to adapt to application for drug controlled-release material. Primarily, CS was extruded to fine fair fiber by spinning after preparing CS solution. CS Block with reticulate structure design were carried out in this experiment. This research will be showed how to choose appropriate molding process, through selecting CS solution concentration and extruding spinning to prepare pure CS fluffy network with fine hair. The CS reticulate body obtained showed good degradation characteristics in simulated body fluid (SBF). The change of morphology to describe its biological characteristics is not only related to material composition but also to the structure of the fluffy network which is mainly controlled by the molding process. Also, the microstructure, morphology and crystallinity of the net CS hydrogels were characterized through Fourier transform infrared spectroscopy and scanning electron microscopy. This research should provide the theory basis and technical way to design and fabricate for CS as the carrier of the drug release.

Study on Shear Rate Effects of Reticulate Red Clay

Direct shear tests were performed to study the shear rate effects of reticulate red clay around Dongting Lake. In the direct shear tests, four sets of undisturbed specimen of reticulate red clay were sheared under the different vertical pressure of 50kPa, 100kPa, 200kPa and 300kPa. Specimens were sheared with six different shear rates of 0.04mm/s, 0.02mm/s, 0.01mm/s, 0.007mm/s, 0.004mm/s and 0.003mm/s under each vertical pressure. Test results show that: (1) shear strength of reticulate red clay increases along with the vertical pressure; (2) shear rate effects of reticulate red clay are affected by vertical pressure significantly; (3) due to its reticulate structure of reticulate red clay, it shows some differences in shear rate effects comparing with other clay.

Tomography-Based Determination of the Effective Thermal Conductivity of Fluid-Saturated Reticulate Porous Ceramics

The effective thermal conductivity of reticulate porous ceramics (RPCs) is determined based on the 3D digital representation of their pore-level geometry obtained by high-resolution multiscale computer tomography. Separation of scales is identified by tomographic scans at 30μm digital resolution for the macroscopic reticulate structure and at 1μm digital resolution for the microscopic strut structure. Finite volume discretization and successive over-relaxation on increasingly refined grids are applied to solve numerically the pore-scale conduction heat transfer for several subsets of the tomographic data with a ratio of fluid-to-solid thermal conductivity ranging from 10−4 to 1. The effective thermal conductivities of the macroscopic reticulate structure and of the microscopic strut structure are then numerically calculated and compared with effective conductivity model predictions with optimized parameters. For the macroscale reticulate structure, the models by Dul’nev, Miller, Bhattachary and Boomsma and Poulikakos, yield satisfactory agreement. For the microscale strut structure, the classical porosity-based correlations such as Maxwell’s upper bound and Loeb’s models are suitable. Macroscopic and microscopic effective thermal conductivities are superimposed to yield the overall effective thermal conductivity of the composite RPC material. Results are limited to pure conduction and stagnant fluids or to situations where the solid phase dominates conduction heat transfer.

Factors Influencing the Ability of Listeria monocytogenes To Pass through a Membrane Filter by Active Infiltration

ABSTRACT Listeria monocytogenes infiltrated the reticulate structure of a membrane filter and passed through a filter with pore sizes of 0.45 μm and 0.2 μm in 6 to 24 h and 5 to 6 days, respectively. Flagellar motility and expansive pressure generated by the growing bacterial population were indicated as the driving forces of infiltration.