Diversity of methanogens in the hindgut of grower and finisher pigs

This study examined the diversity of the methanogens in the hindgut of two different weight groups of pigs and correlated it with the amount of digested organic carbon (OC) and various components of dietary fiber. Five grower (58.9 ± 1.15 kg) and five finisher (89.4 ± 0.85 kg) Duroc × Landrace × Large Yorkshire female pigs were allocated into two groups and individually housed in cages. During the experiment, feed intake and fecal output were recorded for determination of apparent digestibility of OC, crude fiber (CF), neutral detergent fiber (NDF) and acid detergent fiber (ADF). At the end of the digestibility trial, pigs were sacrificed, and the contents of five segments of hindgut were sterilely collected to determine diversity of methanogens. Total microbial DNA of the hindgut contents was used as template for amplification of the methanogen16S rRNA gene, and the PCR products were further subjected to denaturing gradient gel electrophoresis (DGGE) analysis. Results show that the number of DGGE bands and Shannon diversity index for the 90 kg pigs were higher (P<0.05) than those for the 60 kg pigs. Methanogen communities did not alter along the different segments of the hindgut for the two weight groups. In addition, the amount of OC, CF, NDF and ADF digested (g/d) for the 90 kg pigs (1018.77, 23.11, 268.86 and 99.16, respectively) was higher (P<0.05) than the respective values for the 60 kg pigs (669.27, 13.77, 222.31 and 69.07), indicating that the higher diversity of  methanogens in the former group was related to the higher quantity of fiber materials fermented in the hindgut. The positive correlation (p<0.05) between number of DGGE bands and Shannon diversity index with quantity of digested OC and ADF further reaffirmed the above suggestion.Key words: Methanogen, pig, Shannon diversity index, polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE)

Genetic analysis of farmed and wild stocks of large yellow croaker Larimichthys crocea by using microsatellite markers

The large yellow croaker (Pseudosciaena crocea) is one of the most economically important mariculture fish species in China. In this study, the genetic diversity and relationship among a wild stock, four farmed stocks and a selectively bred strain of large yellow croaker were assessed by 14 microsatellite markers. A total of 108 different alleles were detected over all loci. The average number of allele per locus ranged from 5.57 to 7.93, with an average of 6.75; the observed and expected heterozygosity ranged from 0.572 to 0.665 and from 0.649 to 0.751, with an average of 0.621 and 0.694, respectively; the Shannon’s diversity index ranged from 1.34 to 1.64, with an average of 1.48. The selectively bred strain had the lowest genetic diversity; all farmed stocks showed a slight reduction of genetic variability contrasted with wild stock. All stocks suffered severe bottleneck. The pair-wise FST, the phylogenetic tree, the factor correspondence analysis and the model based clustering analysis revealed that, the Ningbo stock, which was from Zhejiang province, was different from the remaining stocks from Fujian province. This study suggested that (1) the farmed stocks were at relatively low level of genetic diversity compared with the wild stock; (2) samples from Ningbo investigated in this study have a distinct divergence with those from Fujian province; (3) there had emerged significant differentiation among farmed stocks.Key words: Pseudosciaena crocea, large yellow croaker, genetic structure, microsatellite markers

In situ loading and delivery of short single- And double-stranded dna by supramolecular organic frameworks

Short DNA represents an important class of biomacromolecules that are widely applied in gene therapy, editing, and modulation. However, the development of simple and reliable methods for their intracellular delivery remains a challenge. Herein, we describe that seven water-soluble, homogeneous supramolecular organic frameworks (SOFs) with a well-defined pore size and high stability in water that can accomplish in situ inclusion of single-stranded (ss) and double-stranded (ds) DNA (21, 23, and 58 nt) and effective intracellular delivery (including two noncancerous and six cancerous cell lines). Fluorescence quenching experiments for single and double endlabeled ss- and ds-DNA support that the DNA sequences can be completely enveloped by the SOFs. Confocal laser scanning microscopy and flow cytometry reveal that five of the SOFs exhibit excellent delivery efficiencies that, in most of the studied cases, outperform the commercial standard Lipo2000, even at low SOF-nucleic acid ratios. In addition to high delivery efficiencies, the watersoluble, self-assembled SOF carriers have a variety of advantages, including convenient preparation, high stability, and in situ DNA inclusion, which are all critical for practical applications in nucleic acid delivery

Numerical simulation of mono-disperse droplet spray dryer under the influence of nozzle motion

With the increasing demand of uniform particles in the fields of medicine etc., the research on monodisperse droplet spray dryer (MDSD) becomes important. The drying efficiency of the current MDSD facility has to be improved to realize industrial applications. In this work, the influence of several kinds of nozzle movement on the drying process has been thoroughly explored by silico experiments. It is found that the velocity of the nozzle movement plays a key role in drying efficiency improvement. The movement of the nozzle leads to a wider distribution of the final moisture content of particles, and this effect becomes less significant with the increase of the velocity of nozzle motion. For all motion types under investigation, the circular motion is superior to the other motion types. It is revealed that the change of droplet dispersion state due to nozzle motion is the main factor that improves drying performance

A quantitative link between microplastic instability and macroscopic deformation behaviors in metallic glasses

Based on mechanical instability of individual shear transformation zones (STZs), a quantitative link between the microplastic instability and macroscopic deformation behavior of metallic glasses was proposed. Our analysis confirms that macroscopic metallic glasses comprise a statistical distribution of STZ embryos with distributed values of activation energy, and the microplastic instability of all the individual STZs dictates the macroscopic deformation behavior of amorphous solids. The statistical model presented in this paper can successfully reproduce the macroscopic stress-strain curves determined experimentally and readily be used to predict strain-rate effects on the macroscopic responses with the availability of the material parameters at a certain strain rate, which offer new insights into understanding the actual deformation mechanism in amorphous solids. © 2009 American Institute of Physics.published_or_final_versio

A quantitative link between microplastic instability and macroscopic deformation behaviors in metallic glasses

2009-2010 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe

Scalable Synthesis of Uniform Mesoporous Aluminosilicate Microspheres with Controllable Size and Morphology and High Hydrothermal Stability for Efficient Acid Catalysis

Mesoporous aluminosilicates are promising solid acid catalysts. They are also excellent supports for transition metal catalysts for various catalytic applications. Synthesis of mesoporous aluminosilicates with controllable particle size, morphology, and structure, as well as adjustable acidity and high hydrothermal stability, is very desirable. In this work, we demonstrate the scalable synthesis of Al-SBA-15 microspheres with controllable physicochemical properties by using the microfluidic jet-spray-drying technology. The productivity is up to ∼30 g of dried particles per nozzle per hour. The Al-SBA-15 microspheres possess uniform controllable micron sizes (27.5-70.2 μm), variable surface morphologies, excellent hydrothermal stability (in pure steam at 800 °C), high surface areas (385-464 m2/g), ordered mesopore sizes (5.4-5.8 nm), and desirable acid properties. The dependence of various properties, including particle size, morphology, porosity, pore size, acidity, and hydrothermal stability, of the obtained Al-SBA-15 microspheres on experimental parameters including precursor composition (Si/Al ratio and solid content) and processing conditions (drying and calcination temperatures) is established. A unique morphology transition from smooth to wrinkled microsphere triggered by control of the Si/Al ratio and solid content is observed. The particle formation and morphology-evolution mechanism are discussed. The Al-SBA-15 microspheres exhibit high acid catalytic performance for aldol-condensation reaction between benzaldehyde and ethyl alcohol with a high benzaldehyde conversion (∼56.3%), a fast pseudo-first-order reaction rate (∼0.1344 h-1), and a high cyclic stability, superior to the commercial zeolite acid (H-ZSM-5). Several influencing factors on the catalytic performance of the obtained Al-SBA-15 microspheres are also studied

Visual Monitoring of Disintegration of Solid Oral Dosage Forms in Simulated Gastric Fluids Using Low-Field NMR Imaging

Compared to traditional drug release monitoring with manual sampling and testing procedures, low-field nuclear magnetic resonance (LF-NMR) imaging is a one-step, visual, non-destructive, and non-invasive measurement method. Here, we reported the application of LF-NMR to image the morphology, component, sub-diffusion, and spatial distribution of a solid oral formulation, Biyankang tablets, during dissolution in vitro. The drug ingredients with characteristic relaxation times were distinguished and localized based on the signal of standards, such as patchouli oil, Xanthium strumarium extract, and starch. The hydration, swelling, disintegration, and sub-diffusion of tablets in simulated gastric fluids (SGF) were visualized statically. All tablets showed similar expansion (37.4–42.0%) along the direction of thickness at 25 min and reached a full disintegration at 145 min, at pH 1.80–6.15, indicating pH-independent swelling and disintegration. Compared to that static immersion within 20 mL SGF, the tablet disintegration time was shortened by ~ 11% in 30 mL SGF. The application of shear reduced the time by ~ 28%, suggesting a major role of hydrodynamic condition in tablet dissolution. The ability to simultaneously visualize, distinguish, and localize drug ingredients using LF-NMR is expected to provide valuable information to develop drug release monitoring systems in vitro and potentially in vivo using small animal studies. Graphical abstract: [Figure not available: see fulltext.

Scalable synthesis of wrinkled mesoporous titania microspheres with uniform large micron sizes for efficient removal of Cr(VI)

Aerosol-assisted methods possess a strong capability for synthesis of titania (TiO2) microspheres. For dynamic separation applications, rough TiO2 microspheres with uniform large micron sizes, high external-surface-area-to-volume ratios, high surface areas, uniform mesopores and abundant hydroxyl groups are desirable. Herein, we demonstrate the combination of evaporation induced self-assembly (EISA) with a microfluidic-jet spray drying process for scalable synthesis of novel mesoporous TiO2 materials with the above-mentioned properties for Cr(vi) removal under both static and dynamic conditions. The TiO2 materials are spherical with uniform large micron sizes (∼45 μm). They possess wrinkled surfaces and thus have high particle external-surface-area-to-volume ratios. They show high surface areas (22-138 m2 g-1), large pore volumes (0.15-0.27 cm3 g-1) and uniform mesopores (5.2-20.7 nm). They carry abundant surface Ti-OH groups due to the presence of oxygen vacancies and the Ti3+ valence state. Several experimental parameters, such as drying and calcination temperatures, are varied, leading to TiO2 samples with tunable surface areas and mesopore sizes. They can be adopted as batch sorbents for removal of Cr(vi) in water with fast adsorption rates, large capacities and pH-dependent adsorption behavior. Part of the adsorbed Cr(vi) can be reduced to Cr(iii) in acidic solutions. The influences of adsorbent properties on adsorption performance are elucidated. Moreover, their uniform large micron sizes make them excellent fillers for efficient separation of Cr(vi) in dynamic flows with similar performance to that under static conditions, as well as easy regeneration and high cycling stability. Their adsorption performance under flowing conditions is much better than those of commercial TiO2 nanoparticles and mesoporous TiO2 materials prepared by a conventional EISA method, which make them very attractive for practical dynamic separation applications