Preparation and properties of thermoplastic starch under the synergism of ultrasonic and elongational rheology.

Thermoplastic starch, as an eco-friendly alternative to petroleum-based plastics, possesses numerous advantages, including cost-effectiveness, complete biodegradability, and renewable sourcing. Nevertheless, the plasticizer dispersion and starch plasticization efficiency are poor via the processing method dominate by shear deformation. Thus, the aim of this study is proposing a new approach combining ultrasonic treatment and elongational rheology to prepare thermoplastic starch and evaluate its properties. This innovative approach facilitated the production of thermoplastic starch with glycerol as the plasticizer at varying rotor speeds. Furthermore, this study was carried out by using a self-developed ultrasonic-assisted vane mixer (UVM) based on elongational flow. The samples were analyzed using FTIR, WAXD, polarized optical microscope, dynamic rheometer, universal testing machine and thermogravimetric analysis. FTIR and dynamic rheological analysis showed that elongational rheology and ultrasonics stimulate hydrogen bond formation between starch and glycerol, elevating starch thermoplasticity. Tensile tests and thermogravimetric analysis highlighted that high-intensity elongational field improved the mechanical properties and thermal stability of the thermoplastic starch. Additionally, the incorporation of ultrasonic treatment yielded further improvements, yielding remarkable tensile strength (6.09 MPa) and elongation at break (139.3 %). This synergistic interplay between ultrasonics and elongational rheology holds immense potential for advancing thermoplastic starch manufacturing.

Oxidization and Chain-Branching Reaction for Recycling HDPE and Mixed HDPE/PP with In-situ Compatibilization by Ozone-Induced Reactive Extrusion.

High-density polyethylene (HDPE) and isotactic polypropylene (iPP) are widely used in industrial and residential applications due to their low cost and chemical stability, thus their recycling process can contribute to a circular economy. However, both polymers are non-polar materials, and the incompatibility with most other materials leads to substantially inferior properties of blends. In this work, we propose a flexible compatibilization strategy to improve the compatibility of HDPE/iPP blends. Ozone is adopted to induce reactive extrusion for rapid oxidation of HDPE and chain-branching reactions for both HDPE and HDPE/iPP blends. During extrusion process, ozone oxidizes HDPE effectively in a short time and introduces oxygen-containing groups such as carbonyl and ester groups, which improves the hydrophilicity. The addition of trimethylolpropane triacrylate (TMPTA) could promote branching reaction and facilitate the formation of HDPE-g-iPP copolymers, which improved the compatibility for HDPE/iPP. As a result, the impact strength of ozone-modified HDPE and HDPE/iPP blends increased by 22 % and 82 %, respectively, and the tensile strength also increased. This strategy would have potential applications in the field of sorting-free and solvent-free recycling of waste polyolefin plastics.

Amelioration of White Matter Injury Through Mitigating Ferroptosis Following Hepcidin Treatment After Spinal Cord Injury.

Spinal cord injury (SCI) usually introduces permanent or long-lasting neurological impairments. Maintaining the integrity of the limited number of white matter bundles (5-10%) preserves wholly or partially locomotor following SCI. Considering that the basic structure of white matter bundles is axon wrapped by oligodendrocytes, promoting oligodendrocytes survival might be a feasible strategy for reducing white matter injury (WMI) after SCI. Oligodendrocytes are rich in unsaturated fatty acid and susceptible to ferroptosis-induced damage. Hence, exploring method to reduce ferroptosis is supposed to expedite oligodendrocytes survival, thereafter mitigating WMI to facilitate functional recovery post-SCI. Here, the results indicated the administration of hepcidin reduced iron accumulation to promote oligodendrocytes survival and to decrease spinal cord atrophy, therefore facilitating functional recovery. Then, the WMI was evidently decreased owing to attenuating ferroptosis. Subsequently, the results revealed that the expression of divalent metal transporter 1 (DMT1) and transferrin receptor (TfR) was expressed in CC1+ cells. The expression level of DMT1 and TfR was significantly increased, while this phenomenon was obviously neutralized with the administration of hepcidin in the epicenter of spinal cord after SCI. Afterward, the application of hepcidin downregulated reactive oxygen species (ROS) overload, which was evidently increased with the treatment of 20 µM FeCl3, therefore increasing cell viability and reducing lactate dehydrogenase (LDH) activity through downregulating the expression of DMT1 and TfR to inhibit ferroptosis in oligodendrocyte progenitor cells (OPCs). The present study provides evidence that the application of hepcidin facilitates oligodendrocytes survival to alleviate WMI via reducing the expression of DMT1 and TfR.

Microsurgical sealing for symptomatic sacral Tarlov cysts: a series of 265 cases.

OBJECTIVE: Tarlov cysts (TCs) are a common cystic entity in the sacral canal, with a reported prevalence between 1.5% and 13.2%; 10%-20% of patients are symptomatic and need appropriate clinical intervention. However, the choice of treatment remains controversial. The goal of this study was to describe a new microsurgical sealing technique for symptomatic sacral TCs (SSTCs) as well as its long-term outcomes. METHODS: Microsurgical sealing was performed using a short incision, leakage coverage with a piece of autologous fat, and cyst sealing with fibrin glue. Postoperative data were collected at three stages: discharge, 1-year follow-up, and a follow-up of 3 years or more. According to the improvement in neurological deficits and degree of pain relief, outcomes were divided into four levels: excellent, good, unchanged, and deteriorated. RESULTS: A total of 265 patients with SSTCs were treated with microsurgical sealing from January 2003 to December 2020. The mean follow-up was 44.69 months. The percentages of patients who benefited from the operation (excellent and good) at the three stages were 87.55%, 84.89%, and 80.73%, respectively, while those who received no benefit (unchanged and deteriorated) were 12.45%, 15.11%, and 19.27%, respectively. Of the patients with postoperative MRI, the cysts were reduced in size or disappeared in 209 patients (94.14%). CSF leakage from the wound was observed in 15 patients, and 4 patients experienced an infection at the incision. There were no cases of new-onset nerve injury or aseptic meningitis after the operation. CONCLUSIONS: SSTC patients undergoing microsurgical sealing had persistently high rates of symptom relief and few postoperative complications. Microsurgical sealing is an effective, simple, and low-risk method for treating SSTCs.

Treatment of symptomatic Chiari I malformation by "all-factors-surgery": a report of 194 cases.

PURPOSE: Inadequate decompressions can lead to poor improvement of symptoms in patients with Chiari I malformation (CMI). In this study, the "all-factors-surgery" that including all levels decompressions was performed on symptomatic CMI patients for the snake of eliminating all possible pathogenic factors and reducing the chance of reoperation. METHODS: The "all-factors-surgery" combined operations of posterior fossa decompression, enlarged cranioplasty, duraplasty, cerebellar tonsil partial resection and adhesion release. Total 194 patients from January 2010 to December 2015. The outcome measures included improvement rate of symptoms, patients self-evaluation (improved, unchanged, worsened), Visual Analogue Scale (VAS) score, Japanese Orthopaedic Association (JOA) score, Chicago Chiari Outcome Scale (CCOS) score, the diameter of the syrinx and complications. RESULTS: Postoperative data were collected from the three stages: at discharge, the short-term follow-up (average, 9.39 months), and the long-term follow-up (average, 54.44 months). Patients self-evaluation improvement rate in the three follow-up stages was 92.27%, 90.07% and 85.93%. The VAS scores (mean, 1.49, 1.21, 1.47 vs 3.76) and JOA scores (mean, 15.66, 15.99, 16.10 vs 14.84) were significant difference between the follow-up and pre-operation (P < .05). The CCOS scores of short-term and long-term follow-up were significantly better than that at discharge (mean, 14.75, 14.87 vs 13.68) (P < .05). The diameter of syrinx in each follow-up stage was significantly less than that in pre-operation (mean, 3.39, 1.95, 1.87 vs 5.09) (P < .05). There were no serious complications, and no one asked for reoperation during the follow up. CONCLUSION: Symptomatic CMI patients undergoing "all-factors-surgery" had persistently high rates of symptom relief and rarely needed reoperation.

Fabrication of Self-Lubricating Porous UHMWPE with Excellent Mechanical Properties and Friction Performance via Rotary Sintering.

Porous ultra-high-molecular-weight polyethylene (UHMWPE) self-lubricating materials were designed and fabricated by a rotary sintering method, and the microstructure and properties were evaluated. Results showed that the rotary molding could not only significantly improve the molding efficiency but also formed uniform internal microstructures with high porosity, excellent mechanical properties, and low friction coefficient. Under oil lubricating conditions, the friction curve of samples quickly reached a steady state, the friction coefficient was reduced by 50%, and the repeat utilization was up to 99%. The following optimum sintering conditions were shown: Sintering temperature of 180 °C or 190 °C, sintering time determined as 10 min, and loading capacity of between 3.6 g and 3.8 g. Therefore, it is expected that this work will open a convenient and compatible strategy for fabricating porous materials with good self-lubricating performance.

Enhancing the Mechanical and Electrical Properties of Poly(Vinyl Chloride)-Based Conductive Nanocomposites by Zinc Oxide Nanorods.

A simple approach to decorate multi-walled carbon nanotube (MWCNT)⁻reduced graphene oxide (RGO) hybrid nanoparticles with zinc oxide (ZnO) nanorods is developed to improve the electrical and mechanical properties of poly(vinyl chloride) (PVC)/MWCNT⁻RGO composites. The ZnO nanorods act as "joint" in three-dimensional (3D) MWCNT⁻RGO networks and the hybrid particles strongly interact with PVC chains via p-π stacking, hydrogen bonds, and electrostatic interactions, which we confirmed by scanning electron microscopy (SEM) and Raman analysis. By introducing the ZnO nanorods, the RGO⁻ZnO⁻MWCNT hybrid particles increased 160% in capacitance compared with MWCNT⁻RGO hybrids. Moreover, the addition of RGO⁻ZnO⁻MWCNT to PVC resulted in the mechanical properties of PVC being enhanced by 30.8% for tensile strength and 60.9% for Young's modulus at the loadings of 2.0 weight percent (wt.%) and 1.0 wt.%, respectively. Meanwhile, the electrical conductivity of PVC increased by 11 orders of magnitude, from 1 × 10-15 S/m to 1 × 10-4 S/m for MWCNT⁻ZnO⁻RGO loading at 5.0 wt.%.

Preparation and characterization of CNTs/UHMWPE nanocomposites via a novel mixer under synergy of ultrasonic wave and extensional deformation.

In this work, design and development of a new melt mixing method and corresponding mixer for polymer materials were reported. Effects of ultrasonic power and sonication time on the carbon nanotubes (CNTs) filled ultra high molecular weight polyethylene (UHMWPE) nanocomposites were experimentally studied. Transmission Electron Microscopy images showed that homogeneous dispersion of CNTs in intractable UHMWPE matrix is successfully realized due to the synergetic effect of ultrasonic wave and extensional deformation without any aid of other additives or solvents. Differential scanning calorimetry results revealed an increase in crystallinity and crystallization rate due to the finer dispersion of the CNTs in the matrix which act as nucleating point. Composites' complex viscosity and storage modulus decreased sharply at first and then leveled off with the increase of sonication time or the ultrasonic power. The thermal stability and the tensile strength of the CNTs/UHMWPE nanocomposites improved by using this novel mixing method. This is the first method that combined the ultrasonic wave and the extensional deformation in which the elongation rate, sonication time and ultrasonic power can be adjusted simultaneously during mixing. The novel mixer offers several advantages such as environment-friendly, high mixing efficiency, self-cleaning and wide adaptability to materials.