Testicular Characteristics and the Block to Spermatogenesis in Mature Hinny

Most hinnies (female donkey×male horse) and mules (female horse×male donkey) are sterile with few reports of equine fertile hybrids. The main cause of this sterility is thought to be a meiotic block to spermatogenesis and oogenesis. This study compared the developmental features of the testes and a histological analyses of spermatogenesis in a male hinny with those of a normal, fertile stallion and Jack donkey. Hinny testes showed a thicker tunica albuginea, fewer blood vessels and more connective tissue in the testis parenchyma than those of the stallion and Jack donkey. Although the mean number of seminiferous tubules was significantly higher in stallion and hinny than Jack donkey (p<0.01), the mean proportion of seminiferous tubules was lower in the hinny (p<0.01) which resulted in a smaller diameter of seminiferous tubules. The mean number of spermatogonia and spermatocytes per unit area were significantly lower in hinny testis (p<0.01) and no spermatids or mature spermatozoa cells were found during immunofluorescent analyses. These results indicated that defects in seminiferous tubule development and structure occur in the testis of hinnies. Furthermore, most spermatogonia and spermatocytes cease development in synapsis during mid-meiosis of spermatocytes, which results in a block to spermatogenesis that prevents the formation of spermatids and matured spermatozoa during meiosis in male hinnies

Oriented Zeolitic imidazolate framework membranes within polymeric matrices for effective N2/CO2 separation

Nanocomposite membranes incorporating high-aspect-ratio nanostructures within polymeric matrices are highly promising for controllable molecular separation. Zeolitic-imidazolate frameworks (ZIFs) has been extensively investigated as nanofillers or surface coating materials devising innovative membrane design. This work for the first time reports an innovative approach to in-situ form ZIFs within polymeric membrane matrix to regulate the molecular sieving behavior of the thin composite layer. A chelation-assisted interfacial reaction strategy was applied to incorporate vertically-oriented ZIF into the crosslinked poly (vinylamine) (PVAm) matrix. PVAm has a good ability to complex with Zn, thus provides a highly concentrated zinc source within the matrix and ensures good adhesion between the ZIFs and substrates. Due to the intimate integration of ZIFs with PVAm, the composite layers have good flexibility and tensile strength. It also leads to the absence of micro-defects within the layer. The membranes exhibited reversed selectivity for the CO/N gas pair, with N/CO selectivity of 51.9 and N permeance of 174.9 GPU. The results of this work provide an important technique to regulate the interfacial interaction to regulate the gas separation behavior within the composite membrane

Enhanced CO2 capture by binary systems of pyridinium-based ionic liquids and porous ZIF-8 particles

Absorption and adsorption technology as widely used methods have been reported for carbon dioxide (CO2) separation. In order to combine the advantages of absorption and adsorption methods, ionic liquids (ILs) as absorption function and zeolitic imidazolate framework-8 (ZIF-8) as adsorption function were integrated into a slurry to efficiently capture CO2 by the absorption-adsorption method. In this study, two pyridinium-based ILs, [C4Py][NTf2] and [C4Py][N(CN)(2)] were synthesized, and mixed with different concentration of ZIF-8 to form hybrid slurries. CO2 solubility in the different hybrid slurries at temperatures from 303.15 to 333.15 K was measured. The results indicated that CO2 solubility increases significantly with increasing pressure and decreases with increasing temperature. Moreover, CO2 solubility increases with the increase of ZIF-8 content, indicating that the addition of ZIF-8 into ILs can obviously enhance CO2 solubility. CO2 solubility in the ZIF-8/[C4Py][NTf2] slurry increases by 24% compared with the corresponding pure IL at 303.15 K and 1.80 MPa. The absorption-adsorption mechanism was studied using FT-IR and NMR spectroscopy. It was demonstrated that CO2 absorption and adsorption in the ZIF-8/ILs hybrid slurries is a physical process. Furthermore, the ZIF-8/[C4Py][NTf2] slurry can also keep the stable absorption performance after five consecutive absorption and desorption cycles. Considering the excellent capacity, thermal stability and recyclability, the porous materials/ILs slurry will provide new insight to CO2 capture compared with the conventional absorbents. (C) 2018 Elsevier Ltd

Heteroepitaxial growth of vertically orientated zeolitic imidazolate framework-L (Co/Zn-ZIF-L) molecular sieve membranes

Despite the extensive potential of zeolitic imidazolate framework (ZIF) membranes in gas separation, the development of continuous, oriented ZIF membranes onto a polymeric substrate remains a significant challenge. This is presumably due to weak adhesion, and insufficient heterogeneous nucleation sites on the polymer surface. Herein, a layer of horizontally aligned poly(sodium-4-styrene sulfonate)-modified halloysite nanotubes (PSS-HNTs) with ample nucleation sites was used for templated growth of vertically oriented Zn-ZIF-L layers. Then we successfully developed the first well-intergrown membranes of Co-ZIF-L on Zn-ZIF-L layers via heteroepitaxial growth. The stepwise deposition was utilized for the control of ZIF films orientation to avoid random nucleation and twins overgrowth. The integration of preferred vertical orientation and optimized grain boundary structure endowed the Co/Zn-ZIF-L membranes with a remarkable gas separation performance (CO2 permeance: 244.9 GPU, and CO2/N-2 selectivity: 17.8). Our methodology provides a useful guideline to design mixed-component, vertically oriented ZIF-L to improve gas separation performance

Zwitterionic functionalized MoS2 nanosheets for a novel composite membrane with effective salt/dye separation performance

© 2018 Elsevier B.V. Polyethersulfone (PES) has been widely used as an ultrafiltration (UF) or nanofiltration (NF) membrane material in multiple industrial fields. But PES is hydrophobic in nature and easily contaminated. Thus, it is necessary to modify the PES membrane surface by physical or chemical methods for improving its hydrophilicity and other function. Herein, MoS2 modified by zwitterionic 2-methacryloyloxy ethyl dimethyl (3-sulfopropyl)-ammonium hydroxide sulfobetaine methacrylate (MoS2-PSBMA) was synthesized with a reverse atom transfer radical polymerization method (RATRP) and used to prepare MoS2-PSBMA/PES composite membranes via conventional phase inversion. The effect of MoS2-PSBMA content on the structure and properties was investigated by SEM, FT-IR, AFM and contact angle measurements. It was found that the hydrophilicity of the composite membrane increased with the content of zwitterionic functionalized MoS2nanosheets. Moreover, the composite membranes possessed a higher water flux (108.3 L m−2 h−1 at 0.6 MPa) and dye retention, 98.2% for Reactive Black 5% and 99.3% for Reactive Green 19. However, the rejection of Na2SO4, MgCl2 NaCl and MgSO4 was low, i.e., 2.2%, 1.2%, 1.1% and 0.3%, respectively. In summary, the synthesized composite membrane exhibited high selectivity for dye/inorganic salts and had a large potential for dye waste water treatment.status: publishe

High flux thin film nanocomposite membranes based on porous organic polymers for nanofiltration

© 2019 Elsevier B.V. Micro-porous organic polymers have garnered tremendous interest in membrane design because of their high nanoscale porosity, superior polymer affinity and chemical stability. In this study, o-hydroxy porous organic polymer (o-POP) utilized as nanofillers were introduced to thin film nanocomposite (TFN) membranes via an interfacial polymerization (IP) process. The o-POP with abundant phenolic –OH limited the diffusion rate of aqueous monomers toward the organic boundary via the robust interactions of electrostatic attraction and hydrogen bonding, as well as increased viscosity of aqueous phase, leading to formation of a regularly crumpled ring-shaped surface and causing a slightly increase in the average pore size of the membrane surface of 0.482 ± 0.03 nm. Such larger pore size surface with abundant bubble, tube or annular pipe structure thus distinctly elevates water transport through the membranes. More importantly, a TFN membrane containing 0.02 wt% o-POP was found to have a high water permeability (29.9 L m −2 h −1 bar −1 ) and an excellent bivalent salt rejection (97.5% for Na 2 SO 4 ), which was three times higher than the water permeability of a commercial nanofiltration (NF) membrane.status: publishe

Estimation of the lateral correlation structure of subsurface water content from surface-based ground-penetrating radar reflection images

Over the past decade, significant interest has been expressed in relating the spatial statistics of surface-based reflection ground-penetrating radar (GPR) data to those of the imaged subsurface volume. A primary motivation for this work is that changes in the radar wave velocity, which largely control the character of the observed data, are expected to be related to corresponding changes in subsurface water content. Although previous work has indeed indicated that the spatial statistics of GPR images are linked to those of the water content distribution of the probed region, a viable method for quantitatively analyzing the GPR data and solving the corresponding inverse problem has not yet been presented. Here we address this issue by first deriving a relationship between the 2-D autocorrelation of a water content distribution and that of the corresponding GPR reflection image. We then show how a Bayesian inversion strategy based on Markov chain Monte Carlo sampling can be used to estimate the posterior distribution of subsurface correlation model parameters that are consistent with the GPR data. Our results indicate that if the underlying assumptions are valid and we possess adequate prior knowledge regarding the water content distribution, in particular its vertical variability, this methodology allows not only for the reliable recovery of lateral correlation model parameters but also for estimates of parameter uncertainties. In the case where prior knowledge regarding the vertical variability of water content is not available, the results show that the methodology still reliably recovers the aspect ratio of the heterogeneity

Natural Nanotube-Based Biomimetic Porous Microspheres for Significantly Enhanced Biomolecule Immobilization

Inorganic nanostructures and their assemblies play important roles in immobilizing biomolecules. Herein, we developed a facile and green methodology to assemble natural halloysite nanotubes (1D building blocks) into nest-like porous microspheres (3D architecture). We further modified the microspheres with dopamine to form a biomimetic entity. The interconnected and hierarchical pores within the microspheres provide larger pore volume to entrap biomolecules, and the abundant functional groups on the pore surface bond covalently with enzyme to enhance the immobilization ability. The porous microspheres showed excellent loading capacity for laccase immobilization as high as 311.2 mg/g, around 30 times higher than the individual halloysite nanotubes (11.3 mg/g). The specific activity above 80% was retained for the immobilized laccase compared to the free laccase. In addition, the immobilized enzyme exhibited remarkable thermal and recycle use stability. The biomimetic microspheres are expected to be biologically safe and chemically stable microcapsules for immobilizing a variety of biomolecules because of their natural and biofriendly characteristics

Surface Modification of Halloysite Nanotubes with Dopamine for Enzyme Immobilization

Halloysite nanotubes (HNTs) have been proposed as a potential support to immobilize enzymes. Improving enzyme loading on HNTs is critical to their practical applications. Herein, we reported a simple method on the preparation of high-enzyme-loading support by modification with dopamine on the surface of HNTs. The modified HNTs were characterized by transmission electron microscopy, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy analyses. The results showed that dopamine could self-polymerize to adhere to the surface of HNTs and form a thin active coating. While the prepared hybrid nanotubes were used to immobilize enzyme of laccase, they exhibited high loading ability of 168.8 mg/g support, which was greatly higher than that on the pristine HNTs (11.6 mg/g support). The immobilized laccase could retain more than 90% initial activity after 30 days of storage and the free laccase only 32%. The immobilized laccase could also maintain more than 90% initial activity after five repeated uses. In addition, the immobilized laccase exhibited a rapid degradation rate and high degradation efficiency for removal of phenol compounds. These advantages indicated that the new hybrid material can be used as a low-cost and effective support to immobilize enzymes

Composite Anion Exchange Membrane from Quaternized Polymer Spheres with Tunable and Enhanced Hydroxide Conduction Property

In this research, novel quaternized polymer spheres (QPSs) with a high quaternary ammonium (QA) group loading amount and a controllable structure are synthesized and incorporated into a chitosan (CS) matrix to fabricate a composite membrane. Systematic characterizations and molecular simulation are adopted to elaborate the relationship between the QA structure of QPSs and physical-chemical as well as ion conduction properties of composite membranes. The well-dispersed QPSs generate repulsive interaction to CS chains, endowing the composite membrane with promoted chain mobility and water uptake and thereby enhanced hydroxide conductivity. The QPSs work as hydroxide conductors within the membranes, affording a hydroxide conductivity increase over 80%. As the hopping sites in the membrane, the QA group with moderate OH^– combination/dissociation capability exhibits higher OH^– conductivity. By comparison, the QA group with the highest or lowest potential displays slightly lower OH^– conductivity. Besides, extending the chain length of the QA ligand generates obvious steric hindrance and then impedes OH^– combination