Inhibition of Autophagy in Renal Cells With Human, Urine-derived, Stem-cell Exosomes to Improve Diabetic Nephropathy.

Context: Clinicians can use stem cells to repair kidney injury. The kidneys' exosome secretions hold the secret to this therapeutic impact. Exosomes from urine-derived stem cells can prevent and treat glomerular damage that diabetes can cause, but the underlying process has remained a mystery. Objective: The study aimed to investigate the protective impact of exosomes from urine-derived stem cells (USCs) against diabetic nephropathy (DN) and to determine the mechanisms involved. Design: The research team performed an animal study. Setting: The study took place at the Affiliated Hospital of Jiujiang University in Jiujiang, Jiangxi, China. Animals: The animals were rats, SD male rats, weighing 200-220g, 40 animals, purchased from Weitong Lihua Experimental Animal Technology Co., Ltd. (certificate number: SCXK (Beijing) 2021-0006). Intervention: Except for a control group, the rats in the groups had induced DN. The five groups, with 10 rats each, were: (1) the negative control group, which received 0.2 ml of PBS solution; (2) the DN group, a second negative control group, which received 0.2 ml of PBS solution, (3) the inhibitor group, an intervention group that received 20 mg/kg of autophagy inhibitor; (4) the exosomes group, an intervention group that received 100 ug/kg of exosomes; and (5) the exosomes + inhibitor group, an intervention group that received 100 ug/kg of exosomes + 20 mg/kg of autophagy inhibitor. From week 8, for four weeks the team injected the inhibitor, exosomes, and exosomes + inhibitor groups with the appropriate treatments using the rats' tail veins. Outcome Measures: The research team: (1) examined the USCs in the exosomes of stem cells; (2) assessed the rats' weights and fasting blood glucose (FBG), using a blood glucose meter; (3) used Coomassie brilliant blue (CBB) staining to determine the amount of protein in the rats' urine and assessed their biochemical indexes; and (4) used Western blot (WB) and a quantitative polymerase chain reaction (Q-PCR) to detect autophagy and the signal transduction pathway. Results: Human exosomes from USCs alleviated injury in the rats that DN caused by reducing urinary-protein levels, serum creatinine (SCR), blood urea nitrogen (BUN), glomerular cell accumulation, and kidney weights. In rats with induced DN, the exosomes + inhibitor significantly reduced the activation of the mTOR signaling pathway, reduced the autophagy of their kidney cells, increased the protein expression of Bcl-2 in the kidney tissues, and lessened the damage to glomerular cells. Conclusions: Human urine-derived stem cell exosomes can significantly reduce the activation of the mTOR signaling pathway, reduce the autophagy of rats' kidney cells, increase the protein expression of LC3B in kidney tissues, and reduce the damage to glomerular cells. By blocking the mTOR signaling pathway, human urogenic exosomes can alleviate the signs and symptoms of DN.

Niobium- and Tantalum-Doped Pt-Sn/Al2 O3 as Efficient Catalysts for Propane Dehydrogenation.

The Pt-Sn/Al2 O3 catalyst has been successfully commercialized for propane dehydrogenation, but it is still highly desirable to further improve its catalytic performance for maximizing the utilization efficiency of noble metal Pt. Herein, this work demonstrates that doping Nb and Ta into Pt-Sn/Al2 O3 has great impacts on its structure, and significantly improved catalytic performances are achieved in Pt-Sn-X/Al2 O3 (X=Nb and Ta). It is found that the incorporation of Nb and Ta into Pt-Sn/Al2 O3 can promote the dispersion of Pt-Sn particles, which results in Pt-Sn clusters being highly dispersed at the surface of Al2 O3 . Moreover, the presence of Nb and Ta makes the SnOx species less reducible, and thus the Pt-Sn particles become more stable at high temperature. Systematic exploration allows to obtain the optimized Pt-Sn-Nb5.0 /Al2 O3 and Pt-Sn-Ta1.0 /Al2 O3 , and these two catalysts exhibit high initial propane conversion (above 43.8 % and 50.4 %) with propylene selectivity of above 98 %. Most importantly, they show excellent regeneration in propane dehydrogenation, and their catalytic performance can be completely restored by a simple calcination.

Versatile Polypropylene Copolymers from a Pilot-Scale Spheripol II Process.

Polypropylene (PP) is one of the most widely used polymers. In this paper, three types of PPs including random PP, impact PP, and impact PP with high clarity, were prepared through a 75 kg/h pilot-scale Spheripol II process. The three produced PPs were produced by the selection or combination the two loops and gas phase reactor and controlling the comonomer and hydrogen concentrations. The three prepared PPs then were pelleted with the clarified nucleating agent NX 8000 and tested for mechanical, thermal, and optical properties. Their molecular structures and rubber phase size were also investigated by GPC, 13C NMR, temperature rising elution fractionation (TREF), XRD, SEM analysis, etc. The results showed that the random PP (PP-1) and the impact PP with high clarity (PP-3) obtained excellent optical transparency with a haze of 12.5% and 13.5% due to their small rubber phase size (roughly ≤ 100 nm), while the impact PP (PP-2) obtained bad transparency with a haze of 98.8% due to the large rubber phase size (about 1 µm) caused by the poor thermal compatibility with the PP matrix. The rubber phase content and ethylene/propylene sequence distributions of the three PPs varied much and resulted in different impact strengths and stiffness properties. PP-2 had a high impact strength of 14.5 kJ/m2 due to the rubber phase generated in the gas phase reactor. Except for the optical transparency, PP-3 gained stiffness and toughness, with 914 MPa of flexural modulus and 25.1 kJ/m2 of impact strength due to the unique molecular structure of its rubber phase.

Toughened High-Flow Polypropylene with Polyolefin-based Elastomers.

Polyolefin is the most widely used and versatile commodity polymer. In this work, three types of polyolefin-based elastomers (PBEs) were adopted to toughen a high-flow polypropylene to improve its overall performance. The chain microstructures of these PBEs, including ethylene/1-octene (E/O) random copolymer from Dow Chemical's polyolefin elastomer (POE), olefin block copolymers (OBCs) of E/O from Dow, and ethylene/propylene random copolymer from ExxonMobil's propylene-based elastomer, were elucidated by GPC, 13C NMR, TREF, and DSC techniques. The mechanical, thermal and optical properties, and morphology analysis of the PP/PBE blends were also studied to investigate the toughening mechanism of these PBEs. The results showed that all three types of PBEs can effectively improve the Izod impact strength of the PP/PBE blends by the addition of the rubber compositions, at the cost of the stiffness. PBE-1 and PBE-2 were found to have a great stiffness-toughness balance with about 1700 MPa of flexural modulus, about 110 °C of HDT and 3.6 kJ/m2 of impact strength on the prepared PP/PBE blends by forming separated rubber phase and refined spherulite crystals. As a result, the OBC with alternating hard and soft segments could achieve a similar toughening effect as the E/P random copolymer. Surprisingly, no obvious rubber phase separation was observed in the PP/PBE-4 blend, which might be due to the good compatibility of the E/P random chains with the isotactic PP; therefore, the PP/PBE blend obtains great toughness performance and optical transparency with the highest Izod impact strength of 4.2 kJ/m2 and excellent transparency.

Structure and Properties of a Metallocene Polypropylene Resin with Low Melting Temperature for Melt Spinning Fiber Application.

An isotactic polypropylene (iPP-1) resin with low melting temperature (Tm) is synthesized by a metallocene catalyst and investigated for melt-spun fiber applications. The structure, thermal and mechanical properties, and feasibility of producing fibers of a commercial metallocene iPP (iPP-2) and a conventional Ziegler-Natta iPP (iPP-3) are carefully examined for comparison. Tm of iPP-1 is about 10 °C lower than the other two samples, which is well addressed both in the resin and the fiber products. Besides, the newly developed iPP-1 possesses higher isotacticity and crystallinity than the commercial ones, which assures the mechanical properties of the fiber products. Thanks to the addition of calcium stearate, its crystal grain size is smaller than those of the two other commercial iPPs. iPP-1 shows a similar rheological behavior as the commercial ones and good spinnability within a wide range of take-up speeds (1200-2750 m/min). The tensile property of fibers from iPP-1 is better than commercial ones, which can fulfill the application requirement. The formation of the mesomorphic phase in iPP-1 during melt spinning is confirmed by the orientation and crystallization investigation with wide angle X-ray diffraction (WAXD), which is responsible for its excellent processing capability and the mechanical properties of the resultant fibers. The work may provide not only a promising candidate for the high-performance PP fiber but also a deep understanding of the formation mechanism of the mesomorphic phase during fiber spinning.

Studies on metal charge density and band gap characteristics produced by the ( n BuCp)2ZrCl2 compound and its reaction mechanism.

The charge density of the central metal atoms and band gap of the compounds were investigated by the Dmol3 software package in Density functional theory (DFT). The band gap of the ( n BuCp)2ZrCl2 compound was the smallest among the listed metallocene compounds, however, its reactivity reached 11.88 kg (mol h)-1 × 104 at the time of slurry polymerization, which was the most active among the catalysts enumerated by the compounds and also verified the Frontier orbital theory. The polymerization of the ( n BuCp)2ZrCl2 compound with olefins proceeded according to the α-agostic mechanism of the ground state and the transition state. Hydrogen molecules were released during the transition state and led to ( n BuCp)2Zr(Cyclopropyl)+ as the final product. The authenticity of the presence of hydrogen in the olefin polymerization gas was confirmed. The aggregation of hydrogen led to a decrease in the activity of the metallocene catalyst, and that was why the energy barrier caused by the first polymerization was much lower than the second polymerization. The present work would provide valuable insight into the characteristics of metallocene catalysts with high activity and low hydrogen evolution.