The XENONnT dark matter experiment

The multi-staged XENON program at INFN Laboratori Nazionali del Gran Sasso aims to detect dark matter with two-phase liquid xenon time projection chambers of increasing size and sensitivity. The XENONnT experiment is the latest detector in the program, planned to be an upgrade of its predecessor XENON1T. It features an active target of 5.9 tonnes of cryogenic liquid xenon (8.5 tonnes total mass in cryostat). The experiment is expected to extend the sensitivity to WIMP dark matter by more than an order of magnitude compared to XENON1T, thanks to the larger active mass and the significantly reduced background, improved by novel systems such as a radon removal plant and a neutron veto. This article describes the XENONnT experiment and its sub-systems in detail and reports on the detector performance during the first science run.

Sleeve gastrectomy links the attenuation of diabetic kidney disease to the inhibition of renal tubular ferroptosis through down-regulating TGF-β1/Smad3 signaling pathway

PURPOSE

To investigate how sleeve gastrectomy (SG), a typical operation of bariatric surgery, attenuated symptom, and progression of diabetic kidney disease (DKD).

METHODS

DKD model was induced by high-fat diet (HFD) combined with streptozocin in Wistar rats. SG was performed, and the group subjected to sham surgery served as control. The animals were euthanized 12 weeks after surgery, followed by sample collection for the subsequent experiment. The HK-2, a renal proximal tubular epithelial cell line derived from human, was utilized to investigate the potential mechanisms.

RESULTS

SG improved metabolic parameters and glucose homeostasis, and could alleviate DKD in terms of renal function indices as well as histological and morphological structures in DM rats, accompanied with a significant reduction in renal tubular injury. Compared with sham group, SG reduced the renal tubular ferroptosis. To further clarify the mechanism involved, in vitro experiments were performed. In the presence of high glucose, renal tubular TGF-β1 secretion was significantly increased in HK-2 cell line, which led to activation of ferroptosis through TGF-β1/Smad3 signaling pathway. Inhibition of TGF-β1 receptor and phosphorylation of Smad3 significantly ameliorated TGF-β1-mediated ferroptosis. In vivo experiments also found that SG improved the hyperglycemic environment, reduced renal TGF-β1 concentrations, and down-regulated the TGF-β1/Smad3 signaling pathway.

CONCLUSIONS

With the capacity to lower the glucose, SG could attenuate the ferroptosis by inhibiting TGF-β1/Smad3 signaling pathway in DKD rats, and eventually attenuated DKD.

[Effect of ground cage use on Oncomelania hupensis spread]

OBJECTIVE

To examine the effect of ground cage use on Oncomelania hupensis spread, so as to provide insights into precision snail control.

METHODS

Twenty ground cages that were frequently used to capture rice field eels were purchased, including 11 packaging tape-made cages, 7 plastic cages and 2 nylon rope-made cages. The eel-capturing activity was mimicked, and 20 ground cages were assigned in settings with relatively high (1.00 snail/0.1 m2 and higher) and low snail densities (< 1.00 snail/0.1 m2) in Xindai Township, Pinghu City, Zhejiang Province during the period from 15 : 00 to 8 : 00 of the following day on April 13, 26 and 28. The numbers of snails carried by different types of ground cages were compared in settings with different types of snail densities using the rank-sum test.

RESULTS

A total of 11 cage-times were assigned in settings with a high snail density, and a total of 77 snails were captured, with a mean number of 7 snails in each cage-time and 2.15 snails in 0.1 m2 ground cage. The mean numbers of snails carried by packaging tape-made and plastic cages were 2.47 snails/0.1 m2 cage and 0.37 snails/0.1 m2 cage, respectively. A total of 24 cage-times were assigned in settings with a low snail density, and a total of 8 snails were captured, with a mean number of 0.33 snails in each cage-time and 0.09 snails in 0.1 m2 ground cage. The mean numbers of snails carried by packaging tape-made cages were 0.12 snails/0.1 m2 cage; however, no snails were carried by plastic or nylon rope-made cages. The number of snails carried by ground cages was higher in settings with a high snail density than in settings with a low snail density (Z = -4.019, P < 0.01), and the number of snails carried by packaging tape-made cages was higher in settings with a high snail density than in settings with a low snail density (Z = -4.086, P < 0.01). No significant differences were found in the numbers of snails carried by different types of ground cages.

CONCLUSIONS

The use of ground cage in snail habitats is a contributor to snail spread.

Risk Factors of Hidden Blood Loss in Unilateral Biportal Endoscopic Surgery for Patients with Lumbar Spinal Stenosis

OBJECTIVE

Unilateral biportal endoscopic (UBE) surgery has recently been used as a minimally invasive procedure for the treatment of lumbar spinal stenosis and is associated with less perioperative blood loss. However, perioperative hidden blood loss (HBL) may be neglected during UBE. This study aimed to examine the volume of HBL and discuss the influential risk factors for HBL during unilateral biportal endoscopic surgery.

METHODS

From January 2022 to August 2022, 51 patients underwent percutaneous unilateral biportal endoscopic surgery for lumbar spinal stenosis at the Department of Spinal Surgery of the Affiliated Traditional Chinese Medicine Hospital of Southwest Medical University and were enrolled in this study. The data included general indicators (age, sex and body mass index [BMI]), underlying disease (hypertension and diabetes), laboratory test results (prothrombin time [PT], activated partial thromboplastin time [APTT], fibrinogen [Fbg]), and preoperative and postoperative hematocrit and hemoglobin), related imaging parameters (severity of intervertebral disc [IVD] degeneration and soft tissue thickness of the interlaminar approach), number of operated vertebrae and operation time. Total blood loss (TBL) and HBL during surgical procedures were measured via the Gross formula. Influential factors were further analyzed by multivariate linear regression analysis and t-tests.

RESULTS

The mean HBL was 257.89 ± 190.66 mL for single-operation patients and 296.58 ± 269.75 mL for two-operation patients. Patients with lower PT (p = 0.044), deeper tissue thickness (p = 0.047), and diabetes mellitus were determined to have more HBL during UBE. The operation time might also be an important factor (p = 0.047). However, sex (p = 0.265), age (p = 0.771/0.624), BMI (p = 0.655/0.664), APTT (p = 0.545/0.751), degree of degenerated IVD (p = 0.932/0.477), and hypertension (p = 0.356/0.896) were not related to HBL.

CONCLUSION

This study determined the different influential factors of HBL during UBE. PT, tissue thickness, and diabetes mellitus are the independent risk factors that affect HBL incidence. Long PT may decrease the volume of HBL within a certain range. Tissue thickness and diabetes mellitus can lead to an increased volume of HBL.

AAV9-based PMM2 gene replacement augments PMM2 expression and improves glycosylation in primary fibroblasts of patients with phosphomannomutase 2 deficiency (PMM2-CDG)

Inherited deficiency of phosphomannomutase 2 (PMM2) (aka PMM2-CDG) is the most common congenital disorders of glycosylation (CDG) and has no cure. With debilitating morbidity and significant mortality, it is imperative to explore novel, safe, and effective therapies for the disease. Our Proof-of-Concept study showed that AAV9-PMM2 infection of patient fibroblasts augmented PMM2 expression and improved glycosylation. Thus, AAV9-PMM2 gene replacement is a promising therapeutic strategy for PMM2-CDG patients.

Noninvasive Radiation Markers Based on Lung Cancer CT Images and Dosimetry Features to Predict the Immune Response to Radiotherapy in Tumor Microenvironment

PURPOSE/OBJECTIVE(S)

For lung cancer patients with complex conditions, doctors need to determine treatment plan in combination with changes of immune response during radiotherapy. It was urgent to find a strategy to predict immune response to intervene the treatment at an early stage.

MATERIALS/METHODS

The radiotherapy process and tumor microenvironment status of 105 lung cancer patients were tracked and recorded in our hospital from 2019 to 2022, public database TCGA-LUAD/LUSC queue of TCIA image data was downloaded as external verification set. Data was analyzed according to the following methods: First, the 3D slicer software was used to process the CT imageomics data, and the doseomics information was calculated by DVHmetrics package from R software. Then Python was brought in to develop a non-invasive radiation scoring system through machine learning methods (T-test, LASSO, random forest and Xgboost). Finally, combined with the clinical information related to the patient's immune response, a nomogram was made to study the correlation between the score markers and the ratio of CD4 cells/CD8 cells in the tumor microenvironment, the prognosis of lung cancer, as well as the incidence of radiation pneumonia.

RESULTS

The radiation markers score formula was obtained with CT imageomics and DVH dosimics features, which achieved an AUC of 0.67-0.75 in predicting CD4/CD8 condition in tumor microenvironment after radiotherapy. It was worth noticing that in predicting the prognosis of lung cancer, it was difficult to distinguish between the radiation score and the patient's survival status (P>0.05). However, we found that the radiation pneumonitis of lung cancer patients in the low score group (42.6%) was significantly higher than that in the high score group (13.4%).

CONCLUSION

Radiation markers score was a non-invasive method to evaluate the immune response of patients with lung cancer, which can be used to predict the incidence of radiation pneumonitis.

First Dark Matter Search with Nuclear Recoils from the XENONnT Experiment

We report on the first search for nuclear recoils from dark matter in the form of weakly interacting massive particles (WIMPs) with the XENONnT experiment, which is based on a two-phase time projection chamber with a sensitive liquid xenon mass of 5.9 ton. During the (1.09±0.03)  ton yr exposure used for this search, the intrinsic ^{85}Kr and ^{222}Rn concentrations in the liquid target are reduced to unprecedentedly low levels, giving an electronic recoil background rate of (15.8±1.3)  events/ton yr keV in the region of interest. A blind analysis of nuclear recoil events with energies between 3.3 and 60.5 keV finds no significant excess. This leads to a minimum upper limit on the spin-independent WIMP-nucleon cross section of 2.58×10^{-47}  cm^{2} for a WIMP mass of 28  GeV/c^{2} at 90% confidence level. Limits for spin-dependent interactions are also provided. Both the limit and the sensitivity for the full range of WIMP masses analyzed here improve on previous results obtained with the XENON1T experiment for the same exposure.

"Double-edged sword" effect of reactive oxygen species (ROS) in tumor development and carcinogenesis

Reactive oxygen species (ROS) are small reactive molecules produced by cellular metabolism and regulate various physiological and pathological functions. Many studies have shown that ROS plays an essential role in the proliferation and inhibition of tumor cells. Different concentrations of ROS can have a "double-edged sword" effect on the occurrence and development of tumors. A certain concentration of ROS can activate growth-promoting signals, enhance the proliferation and invasion of tumor cells, and cause damage to biomacromolecules such as proteins and nucleic acids. However, ROS can enhance the body's antitumor signal at higher levels by initiating oxidative stress-induced apoptosis and autophagy in tumor cells. This review analyzes ROS's unique bidirectional regulation mechanism on tumor cells, focusing on the key signaling pathways and regulatory factors that ROS affect the occurrence and development of tumors and providing ideas for an in-depth understanding of the mechanism of ROS action and its clinical application.

Searching for Heavy Dark Matter near the Planck Mass with XENON1T

Multiple viable theoretical models predict heavy dark matter particles with a mass close to the Planck mass, a range relatively unexplored by current experimental measurements. We use 219.4 days of data collected with the XENON1T experiment to conduct a blind search for signals from multiply interacting massive particles (MIMPs). Their unique track signature allows a targeted analysis with only 0.05 expected background events from muons. Following unblinding, we observe no signal candidate events. This Letter places strong constraints on spin-independent interactions of dark matter particles with a mass between 1×10^{12} and 2×10^{17}  GeV/c^{2}. In addition, we present the first exclusion limits on spin-dependent MIMP-neutron and MIMP-proton cross sections for dark matter particles with masses close to the Planck scale.

Preparation of silk fibroin/hyaluronic acid composite hydrogel based on thiol-ene click chemistry

OBJECTIVES

To design and prepare silk fibroin/hyaluronic acid composite hydrogel.

METHODS

The thiol modified silk fibroin and the double-bond modified hyaluronic acid were rapidly cured into gels through thiol-ene click polymerization under ultraviolet light condition. The grafting rate of modified silk fibroin and hyaluronic acid was characterized by 1H NMR spectroscopy; the gel point and the internal microstructure of hydrogels were characterized by rheological test and scanning electron microscopy; the mechanical properties were characterized by compression test; the swelling rate and degradation rate were determined by mass method. The hydrogel was co-cultured with the cells, the cytotoxicity was measured by the lactate dehydrogenase method, the cell adhesion was measured by the float count method, and the cell growth and differentiation on the surface of the gel were observed by scanning electron microscope and fluorescence microscope.

RESULTS

The functional group substitution degrees of modified silk fibroin and hyaluronic acid were 17.99% and 48.03%, respectively. The prepared silk fibroin/hyaluronic acid composite hydrogel had a gel point of 40-60 s and had a porous structure inside the gel. The compressive strength was as high as 450 kPa and it would not break after ten cycles. The water absorption capacity of the composite hydrogel was 4-10 times of its own weight. Degradation experiments showed that the hydrogel was biodegradable, and the degradation rate reached 28%-42% after 35 d. The cell biology experiments showed that the cytotoxicity of the composite gel was low, the cell adhesion was good, and the growth and differentiation of the cells on the surface of the gel were good.

CONCLUSIONS

The photocurable silk fibroin/hyaluronic acid composite hydrogel can form a gel quickly, and has excellent mechanical properties, adjustable swelling rate and degradation degree, good biocompatibility, so it has promising application prospects in biomedicine.

[Efficacy of video-assisted thoracoscopic surgical decortication for stage Ⅲ tuberculous empyema]

Objective: To investigate the clinical efficacy, safety and feasibility of "double-portal" video-assisted thoracoscopic surgical(VATS) decortication among patients with stage Ⅲ tuberculous empyema, and then to evaluate the recovery of chest deformity. Method: This study was a single center retrospective study. A total of 49 patients with stage Ⅲ tuberculous empyema who underwent VATS pleural decortication at the Department of Thoracic Surgery, Public Health Clinical Center of Chengdu between June 2017 and April 2021 were enrolled, including 38 males, and 11 females, aged 13-60 (27.5±10.4) years. The safety and feasibility of VATS were further evaluated. The inner circumference of the chest on sternal and xiphoid planes on chest CT scans before and 1, 3, 6, 12months after decortication were collected through the measuring software of the CT. The samples in-pair test was used to compare the changes in the chest to reflect the recovery of the chest deformity. Results: In the 49 patients, The surgical time was (186±61) min, and the volume of blood loss was (366±267) ml. There were 8 cases (16.33%) with postoperative complications during the perioperative period. Constant air leak and pneumonia were the main postoperative complications. No relapse of empyema or dissemination of tuberculosis occured during the period of follow-up. Before surgery, the inner thoracic circumference of the thorax at the level of the carina plane was (655±54) mm, and the inner thoracic circumference of the thorax at the level of the xiphoid plane was (720±69) mm. Patients were followed for 12-36 months. The inner thoracic circumference of the thoracic cavity at the level of carina was (666±51), (667±47) and (671±47) mm at the 3rd, 6th and 12th months after operation, which were significantly larger than that at the level of carina before operation (all P<0.05). The inner thoracic circumference diameter of the thoracic cavity measured at the xiphoid level at the 3rd, 6th and 12th months after the operation was (730±65), (733±63) and (735±63) mm respectively(all P<0.05).The inner thoracic circumference of the thoracic cavity increased significantly than that before surgery (P<0.05). At 6 months after operation, there was significant difference in the improvement of the inner thoracic circumference of the carina plane in patients with age less than 20 years and FEV₁% less than 80% (P=0.015, P=0.003). The improvement in the inner thoracic circumference of the carina plane in patients with pleural thickening≥8 mm compared with those with less than 8 mm was not statistically different(P=0.070). Conclusions: For some patients with stage Ⅲ tuberculous empyema, pleural decortication under thoracoscopy is safe and feasible, and can significantly restore the inner thoracic circumference of the patient's chest, improve the collapse of the patient's chest, and have significant clinical effect. The "double-portal VATS" surgical technology has the advantage of less trauma, wide operation field, large operation space and is easy to master, which is worth further exploring for clinical application.

An interpretable machine learning model for real-time sepsis prediction based on basic physiological indicators

OBJECTIVE

In view of the important role of risk prediction models in the clinical diagnosis and treatment of sepsis, and the limitations of existing models in terms of timeliness and interpretability, we intend to develop a real-time prediction model of sepsis with high timeliness and clinical interpretability.

PATIENTS AND METHODS

We used eight real-time basic physiological monitoring indicators of patients, including heart rate, respiratory rate, oxygen saturation, mean arterial pressure, systolic blood pressure, diastolic blood pressure, temperature and blood glucose, extracted three-hour dynamic feature sequences, and calculated 3 linear parameters (mean, standard deviation, and endpoint value), a 24-dimensional feature vector was constructed, and finally a real-time sepsis prediction model was constructed based on the Local Interpretable Model-Agnostic Explanation (LIME) interpretability method.

RESULTS

The area under the receiver operating characteristic curve (AUROC), Accuracy and F1 scores of Extremely Randomized Trees we built were higher than those of other models, with AUROC above 0.76, showing the best performance. The Imbalance XGBoost has a high specificity (0.86) in predicting sepsis. The LIME local interpretable model we built can display a large amount of valid model prediction details for clinical workers' reference, including the prediction probability and the influence of each feature on the prediction result, thus effectively assisting the work of clinical workers and improving diagnostic efficiency.

CONCLUSIONS

This model can provide real-time dynamic early warning of sepsis for critically ill patients under supervision and provide a reference for clinical decision support. At the same time, interpretive analysis of sepsis prediction models can improve the credibility of the models.

[Uterine POLE mutant endometrioid carcinoma combined with human papilloma virus-associated cervical adenocarcinoma: A case report and literature review]

Independent primary uterine and cervical adenocarcinoma are rare and difficult to identify their origins, which makes treatment decision difficult. A 46-year-old female with endometrioid carcinoma and adenocarcinoma, human papilloma virus (HPV)-associated of the uterine cervix was reported. The patient presented with increased menstrual flow, contact bleeding and watery leucorrhea for more than one year, and the imaging findings showed abnormal uterine morphology, irregular margins, and multiple abnormal signals in uterine cavity and myometrium, which suggested multiple leiomyomas of the uterus. The signal intensity in the right muscle layer was markedly enhanced, suggesting a smooth muscle tumor of uncertain malignant potential. A large number of cystic hypointensity was seen in the cervix, and multiple cysts were considered. The initial preoperative diagnosis was multiple leiomyoma of the uterus, and a hysterectomy operation was planned. During the operation, the uterus was sent for frozen sections. There was a mass in the endometrium of the fundus, with a soft grayish-red cut surface and a clear border with the myometrium, and there was a grayish-white nodule in the cervix with a hard grayish-white cut surface. The two masses were well demarcated from each other, and the distance between them was 30 mm. The result of the frozen sections indicated the malignant tumor of the endometrium, and the extended hysterectomy+pelvic lymphadenectomy+partial resection of the greater omentum was performed. After the operation, the paraffin sections were sent to the Department of Pathology of the Peking University Third Hospital for histochemistry, POLE gene sequencing and HPV RNAscope tests, and the final diagnosis was a synchronous endometrioid carcinoma (POLE-mutant according to the WHO classification) and an adenocarcinoma, HPV-associated of the uterine cervix. Now the patient had been treated with 2 cycles of chemotherapy and her condition was fine. Through the analysis of the histological, immunohistochemical and molecular detection results of this case, the importance of applying HPV RNAscope and TCGA molecular typing in the diagnosis of cervical adenocarcinomas and endometrial carcinomas was emphasized. At the same time, gynecologists should not blindly rely on intraoperative frozen sections, and should pay attention to preoperative pathological examination, and make appropriate operation methods according to the results in order to prevent passivity in the surgery.

The Injected Foaming Study of Polypropylene/Multiwall Carbon Nanotube Composite with In Situ Fibrillation Reinforcement

This paper explored the injection foaming process of in situ fibrillation reinforced polypropylene composites. Using polypropylene (PP) as the continuous phase, polytetrafluoroethylene (PTFE) as the dispersed phase, multi-wall carbon nanotubes (MWCNTs) as the conductive filler, and PP grafted with maleic anhydride (PP-g-MA) as the compatibilizer, a MWCNTs/PP-g-MA masterbatch was prepared by using a solution blending method. Then, a lightweight, conductive PP/PTFE/MWCNTs composite foam was prepared by means of extruder granulation and supercritical nitrogen (ScN₂) injection foaming. The composite foams were studied in terms of rheology, morphological, foaming behavior and mechanical properties. The results proved that the in situ fibrillation of PTFE can have a remarkable effect on melt strength and viscoelasticity, thus improving the foaming performance; we found that PP/3% PTFE showed excellent performance. Meanwhile, the addition of MWCNTs endows the material with conductive properties, and the conductivity reached was 2.73 × 10^-5 S/m with the addition of 0.2 wt% MWCNTs. This study's findings are expected to be applied in the lightweight, antistatic and high-performance automotive industry.

Search for New Physics in Electronic Recoil Data from XENONnT

We report on a blinded analysis of low-energy electronic recoil data from the first science run of the XENONnT dark matter experiment. Novel subsystems and the increased 5.9 ton liquid xenon target reduced the background in the (1, 30) keV search region to (15.8±1.3)  events/(ton×year×keV), the lowest ever achieved in a dark matter detector and ∼5 times lower than in XENON1T. With an exposure of 1.16 ton-years, we observe no excess above background and set stringent new limits on solar axions, an enhanced neutrino magnetic moment, and bosonic dark matter.

[Bedside monitoring of lung perfusion by electrical impedance tomography]

As a non-invasive and radiation-free bedside imaging method, electrical impedance tomography (EIT) can perform real-time regional pulmonary ventilation evaluation and pulmonary blood flow monitoring for patients, thus realizing bedside ventilation/perfusion matching visualization, effectively guiding the pathophysiological mechanism of hypoxemia, and providing a new method for the study of pulmonary blood flow. EIT has also played a unique and irreplaceable role in COVID-19 research and treatment. At the same time, as functional imaging, the operation details and image reconstruction algorithm of this technology still need to be further optimized by more researches to provide a more robust evaluation in clinical application. In this paper, EIT pulmonary blood flow monitoring methods, operation and implementation of monitoring indicators, application and related research progress will be described.

Material radiopurity control in the XENONnT experiment

The selection of low-radioactive construction materials is of the utmost importance for rare-event searches and thus critical to the XENONnT experiment. Results of an extensive radioassay program are reported, in which material samples have been screened with gamma-ray spectroscopy, mass spectrometry, and \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$^{222}$$\end{document}222Rn emanation measurements. Furthermore, the cleanliness procedures applied to remove or mitigate surface contamination of detector materials are described. Screening results, used as inputs for a XENONnT Monte Carlo simulation, predict a reduction of materials background (\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\sim $$\end{document}∼17%) with respect to its predecessor XENON1T. Through radon emanation measurements, the expected \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$^{222}$$\end{document}222Rn activity concentration in XENONnT is determined to be 4.2 (\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$^{+0.5}_{-0.7}$$\end{document}-0.7+0.5) \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\upmu $$\end{document}μBq/kg, a factor three lower with respect to XENON1T. This radon concentration will be further suppressed by means of the novel radon distillation system.

Effect of tiny amount of DMC on thermal, mechanical, optical, and water resistance properties of poly(vinyl alcohol)

In this paper, tiny amount of methacryloxyethyl trimethylammonium chloride (DMC) was added in poly(vinyl alcohol) (PVA) in order to widen its thermoplastic processing window. The effects of DMC content on thermal, mechanical, optical, and water resistance were investigated. The results showed that the thermal stability of PVA/DMC was improved obviously. Compared with pure PVA, with tiny amount (∼0.6 wt%) of DMC, the initial decomposition temperature and the fastest decomposition temperature of DMC/PVA increased from 246 °C and 287.6 °C–320.8 °C and 364.8 °C respectively. Moreover, this tiny amount of DMC did not affect the crystallization performance of PVA. PVA/DMC (0.6 wt%) blend have similar mechanical, optical properties and low temperature water resistance as those pure PVA have. The melting temperature of the PVA/DMC remained at 221 °C as that of pure PVA. This work might provide a new method for widening the thermoplastic processing window of PVA without sacrificing its other inherent properties. The reasons why DMC could improve the thermal stability for PVA was explored as well.

Pressure-induced flow processing behind the superior mechanical properties and heat-resistance performance of poly(butylene succinate)

We propose a pressure-induced flow (PIF) processing method for the simultaneous enhancement of strength, toughness, and heat resistance of biodegradable poly(butylene succinate) (PBS). The pressure and temperature were systematically adjusted to optimize the tensile strength of PBS. Under the optimized processing conditions, the structured PBS was characterized by relatively high strength of 89.5 MPa, toughness of 21.4 kJ·m−2, and improved heat resistance without deterioration of much of its ductility. Microscopic analyses witnessed denser and highly oriented crystalline domains along the flow direction caused by PIF processing. Detailed crystallization analysis made by 2D-WAXD and 2D-SAXS unraveled the extremely ordered PBS domains, which were featured by a significant increase in the orientation degree from 0.25 for the reference to 0.73 for PIF-processed PBS. Such a highly ordered microstructure substantially boosted the degree of crystallinity and heat-resistance temperature of PBS. We believe that our findings would offer a facile, green, and cost-effective approach for fabricating biodegradable polymers with outstanding properties and performance.