Photoinduced decarboxylative germylation of α-fluoroacrylic acids: access to germylated monofluoroalkenes.

Herein, a novel strategy is presented for the photoinduced decarboxylative and dehydrogenative cross-coupling of a wide range of α-fluoroacrylic acids with hydrogermanes. This methodology provides an efficient and robust approach for producing various germylated monofluoroalkenes with excellent stereoselectivity within a brief photoirradiation period. The feasibility of this reaction has been demonstrated through gram-scale reaction, conversion of germylated monofluoroalkenes, and modification of complex organic molecules.

Volatile carbonyl metabolites analysis of nanoparticle exposed lung cells in an organ-on-a-chip system.

The evaluation of nanoparticles (NPs) cytotoxicity is crucial for advancing nanotechnology and assessing environmental pollution. However, existing methods for NPs cytotoxicity evaluation suffer from limited accuracy and inadequate information content. In the study, we developed a novel detection platform that enables the identification of cellular carbonyl metabolites at the organ level. The platform is integrated with a cell co-culture lung organ chip (LOC) and a micropillar concentrator. Notably, our work represents the successful measurement of the amounts of cellular metabolites on LOC system. The volatile carbonyl metabolites (VCMs) generated by cells exposure to various types of NPs with different concentrations were captured and detected by high-resolution mass spectrometry (MS). Compared with conventional cell viability and reactive oxygen species (ROS) analysis, our method discerns the toxicological impact of NPs at low concentrations by analyzed VCM at levels as low as ppb level. The LOC system based metabolic gas detection confirmed that low concentrations of NPs have a toxic effect on the cell model, which was not reflected in the fluorescence detection, and the effect of NP material is more significant than the size effect. Furthermore, this method can distinguish different NPs acting on cell models through cluster analysis of multiple VCMs.

Photoinduced Decarboxylative Difluoroalkylation and Perfluoroalkylation of α-Fluoroacrylic Acids.

Herein, a novel and practical methodology for the photoinduced decarboxylative difluoroalkylation and perfluoroalkylation of α-fluoroacrylic acids is reported. A wide range of α-fluoroacrylic acids can be used as applicable feedstocks, allowing for rapid access to structurally important difluoroalkylated and polyfluoroalkylated monofluoroalkenes with high Z-stereoselectivity under mild conditions. The protocol demonstrates excellent functional group compatibility and provides a platform for modifying complex biologically active molecules.

Multifunctional Therapeutic Nanodiamond Hydrogels for Infected-Wound Healing and Cancer Therapy.

Wound infection and tumor recurrence are the two main threats to cancer patients after surgery. Although researchers have developed new treatment systems to address the two significant challenges simultaneously, the potential side effects of the heavy-metal-ion-based treatment systems still severely limit their widespread application in therapy. In addition, the wounds from tumor removal compared with general operative wounds are more complex. The tumor wounds mainly exhibit more hemorrhage, larger trauma area, greater vulnerability to bacterial infection, and residual tumor cells. Therefore, a multifunctional treatment platform is urgently needed to integrate rapid hemostasis, sterilization, wound healing promotion, and antitumor functions. In this work, nanodiamonds (NDs), a material that has been well proven to have excellent biocompatibility, are added into a solution of acrylic-grafted chitosan (CEC) and oxidized hyaluronic acid (OHA) to construct a multifunctional treatment platform (CEC-OHA-NDs). The hydrogels exhibit rapid hemostasis, a wound-healing-promoting effect, excellent self-healing, and injectable abilities. Moreover, CEC-OHA-NDs can effectively eliminate bacteria and inhibit tumor proliferation by the warm photothermal effect of NDs under tissue-penetrable near-infrared laser irradiation (NIR) without cytotoxicity. Consequently, we adopt a simple and convenient strategy to construct a multifunctional treatment platform using carbon-based nanomaterials with excellent biocompatibility to promote the healing of infected wounds and to inhibit tumor cell proliferation simultaneously.

Differences in anterior chamber depth in keratoconus patients with binocular very asymmetry ectasia.

BACKGROUND: To evaluate the difference in anterior chamber depth (ACD) between two eyes among keratoconus patients with binocular very asymmetric ectasia (VAE) and to explore the influencing factors. METHODS: The corneal curvature and ACD in both eyes of patients with VAE were measured by Sirius (version 3.2, CSO, Italy) at the following points: corneal vertex, maximum curvature (apex), and the 1.5 mm, 2.5 mm, and 3.5 mm superior-, inferior-, nasal-, temporal-paracentral from center. The mean pupil power (MPP) and corneal morphology parameters were also measured. Correlations between ACD and curvature and morphology parameters were analyzed by linear regression. RESULTS: 172 eyes of 86 patients (9 to 45 years) were classified into the VAE-N (n = 86) group and the VAE-E group (n = 86) based on the corneal morphology. The central (3.32 ± 0.27 mm versus 3.43 ± 0.29 mm, P < 0.001) and paracentral ACDs increased significantly in the VAE-E group, and the corneal morphology parameters were also significantly higher. The central ACD was significantly correlated with the MPP (r = 0.465), KVf/b (Keratoconus Vertex front/back) (r = 0.306, r = 0.327), and BCVf/b (Baiocchi Calossi Versaci front/back) (r = 0.356, r = 0.416). Linear regression showed good relationships between △ACD and △MPP (R2 = 0.429) and △KVf/b (R2 = 0.504, R2 = 0.536). CONCLUSIONS: The ACD was larger in the VAE-E group. The difference in ACD between the VAE-E and VAE-N groups was significantly correlated with corneal curvature and the extent of corneal elevation, indicating the influences of both the corneal magnification effect and corneal ectasia on ACD.

Severe/critical COVID-19 early warning system based on machine learning algorithms using novel imaging scores.

BACKGROUND: Early identification of severe/critical coronavirus disease 2019 (COVID-19) is crucial for timely treatment and intervention. Chest computed tomography (CT) score has been shown to be a significant factor in the diagnosis and treatment of pneumonia, however, there is currently a lack of effective early warning systems for severe/critical COVID-19 based on dynamic CT evolution. AIM: To develop a severe/critical COVID-19 prediction model using a combination of imaging scores, clinical features, and biomarker levels. METHODS: This study used an improved scoring system to extract and describe the chest CT characteristics of COVID-19 patients. The study also took into consideration the general clinical indicators such as dyspnea, oxygen saturation, alternative lengthening of telomeres (ALT), and androgen suppression treatment (AST), which are commonly associated with severe/critical COVID-19 cases. The study employed lasso regression to evaluate and rank the significance of different disease characteristics. RESULTS: The results showed that blood oxygen saturation, ALT, IL-6/IL-10, combined score, ground glass opacity score, age, crazy paving mode score, qsofa, AST, and overall lung involvement score were key factors in predicting severe/critical COVID-19 cases. The study established a COVID-19 severe/critical early warning system using various machine learning algorithms, including XGBClassifier, Logistic Regression, MLPClassifier, RandomForestClassifier, and AdaBoost Classifier. The study concluded that the prediction model based on the improved CT score and machine learning algorithms is a feasible method for early detection of severe/critical COVID-19 evolution. CONCLUSION: The findings of this study suggest that a prediction model based on improved CT scores and machine learning algorithms is effective in detecting the early warning signals of severe/critical COVID-19.

Stereoselective Synthesis of Monofluoroalkenylphosphine Oxides via Photoinduced Decarboxylative Coupling of α-Fluoroacrylic Acids with P(O)H Compounds.

Herein, a practical and efficient method for synthesizing monofluoroalkenyl phosphine oxides via photoinduced decarboxylative/dehydrogenative coupling of α-fluoroacrylic acids with phosphine oxides and phosphonates has been developed. Various α-fluoroacrylic acids and P(O)H compounds containing relevant functional groups, including tetrafluorobenzene and pentafluorobenzene, were converted into corresponding products with excellent E-stereoselectivity in satisfactory yields. This method can be extended to achieve the synthesis of monofluoroalkenyl silanes under similar conditions.

Changes in Anterior Chamber After Myopic and Hyperopic FS-LASIK.

INTRODUCTION: This study evaluated the changes and explored influential factors in the anterior chamber after femtosecond laser-assisted in situ keratomileusis (FS-LASIK) on the basis of patients with different degrees of myopia, refractive status, and age. METHODS: Patients underwent uneventful FS-LASIK for the treatment of ametropia. All patients with myopia were classified into a low age group (18-40 years) or high age group (> 40 years). Patients in the low age group (18-40 years) were subdivided into myopia and hyperopia groups. According to the preoperative spherical equivalent values, the myopia group was further divided into low myopia, moderate myopia, and high myopia groups. We measured the magnitude of anterior chamber depth (ACD), angle (ACA), volume (ACV), lens rise, central corneal thickness (CCT), and mean pupil power (MPP) of all patients using Sirius (version 3.2, CSO, Italy) before and 3 months post operation. RESULTS: A total of 140 eyes of 87 patients were evaluated. The magnitudes of ACD, ACA, and ACV decreased significantly postoperatively in both low age (P < 0.001, P < 0.001, P < 0.001, respectively) and high age group (P < 0.001, P < 0.001, P < 0.001, respectively) of patients with myopia, while an increasing tendency of ACD (2.85 ± 0.38 mm preoperatively vs 2.89 ± 0.09 mm postoperatively) and ACA (39.16° ± 7.30° preoperatively vs 39.37° ± 7.68° postoperatively) was found in hyperopia. There was no correlation between different degrees of myopia and the changes in the anterior chamber. CONCLUSIONS: Anterior chamber parameters decreased significantly and approximately in the same degree in low and high age groups postoperatively, while an increasing tendency of ACD and ACA was found in hyperopia, indicating that it is probably a corneal magnification effect that influences changes in the anterior chamber.

Toughened Hydrogels for 3D Printing of Soft Auxetic Structures.

Materials with negative Poisson's ratio have attracted considerable attention and offered high potential applications as biomedical devices due to their ability to expand in every direction when stretched. Although negative Poisson's ratio has been obtained in various base materials such as metals and polymers, there are very limited works on hydrogels due to their intrinsic brittleness. Herein, we report the use of methacrylated cellulose nanocrystals (CNCMAs) as a macro-cross-linking agent in poly(2-hydroxyethyl methacrylate) (pHEMA) hydrogels for 3D printing of auxetic structures. Our developed CNCMA-pHEMA hydrogels exhibit significant improvements in mechanical properties, which is attributed to the coexistence of multiple chemical and physical interactions between the pHEMA and CNCMAs. Structures printed by using CNCMA-pHEMA hydrogels show auxetic behavior with greatly enhanced toughness and stretchability compared to the hydrogel with a traditional cross-linking agent. Such strong and tough auxetic hydrogels would contribute toward establishing advanced flexible implantable devices such as biodegradable oesophageal self-expandable stents.

Cytotoxic Indolocarbazoles From a Marine-Derived Streptomyces Sp. OUCMDZ-5380.

Under the guidance of global natural product social molecular networking, three new indolocarbazoles named streptocarbazoles F-H (1-3), along with staurosporine (4) were isolated from the marine-derived Streptomyces sp. OUCMDZ-5380. Structures of streptocarbazoles F-H were, respectively, determined as N-demethyl-N-hexanoylstaurosporine (1), N-demethyl-N-(2-methyl-3-methoxypyridin-4-yl) staurosporine staurosporine (2), and 4-(N-demethylstaurosporine-N-yl)-1,2-dimethyl-3-methoxypyridinium (3) by spectroscopic analysis and electronic circular dichroism comparison with staurosporine. Compared with staurosporine (4), streptocarbazoles F-H (1-3) showed a selective antiproliferation of the acute myeloid leukemia cell line MV4-11 with the IC50 values of 0.81, 0.55, and 1.88 µM, respectively.

Tilt and decentration with various intraocular lenses: A narrative review.

We find that tilt and decentration of intraocular lens (IOL) commonly cause visual quality deterioration after cataract surgery. Multiple factors affect IOL tilt and decentration in the pre-, mid-, and post-operation phases. Moreover, the tilt and decentration of 1-piece IOL are less correlated with internal ocular HOAs than those of 3-piece IOL. Aspherical IOLs are more sensitive to decentration or tilt than spherical IOLs. Furthermore, the optical performance of toric IOLs with an accurate axis remains stable irrespective of tilt and decentration. The optical quality of asymmetric multifocal IOLs varies significantly after decentration and tilt in different directions. The image quality enhances or deteriorates in the direction of the decentered IOL. An extended depth of focus IOL can achieve good visual acuity in the distant, intermediate, and near range. Additionally, its tilt and decentration have less impact on the vision than bifocal and trifocal IOL. This is the first review that compares the effect of IOL tilt and decentration on image quality for various IOL designs. The result indicates that a deeper understanding of tilt and decentration of various IOLs can help achieve a better visual effect to visually improve refractive cataract surgery.

CuS-PNIPAm nanoparticles with the ability to initiatively capture bacteria for photothermal treatment of infected skin.

Copper sulfide nanoparticles (CuS NPs) have shown great potential in various application fields, especially in biomedical engineering fields. CuS NPs, with the ability to actively capture and kill bacteria and without the worry of biocompatibility, will greatly expand their applications. Herein, a four-arm star thermo-sensitive polyisopropylacrylamide (4sPNIPAm) was used to modify CuS NPs (CuS-PNIPAm NPs). The obtained NPs displayed the controlled release of copper ions and higher photothermal conversion ability in comparison with contrast materials CuS-PEG NPs and CuS NPs. Aggregation of CuS-PNIPAm NPs at above 34°C resulted in capturing bacteria by forming the aggregates of NPs-bacteria. Both Staphylococcus aureus and Escherichia coli co-cultured with CuS-PNIPAm NPs were completely killed upon near-infrared irradiation in minutes. Furthermore, CuS-PNIPAm NPs were verified to be a photothermal agent without toxic effect. In in vivo experiment, the NPs effectively killed the bacteria in the wound and accelerated the process of wound repairment. Overall, photothermal treatment by CuS-PNIPAm NPs demonstrates the ability to actively capture and kill bacteria, and has a potential in the treatment of infected skin and the regeneration of skin tissues. The therapy will exert a far-reaching impact on the regeneration of stubborn chronic wounds.

Epibulbar osseous choristoma: Two case reports.

BACKGROUND: Choristoma is a rare, benign, congenital proliferative tumor, with osseous choristoma being the rarest. Although the tumor is benign, effective identification is needed for its diagnosis and treatment. Here, we report the diagnosis and successful surgical treatment of two patients with osseous choristoma. CASE SUMMARY: Two patients, a young female and young male patient, were found to have a mass on the ocular surface. The tumor presented on the superior temporal bulbar conjunctiva in the first patient and on the upper eyelid in the second patient. Ultrasound biomicroscopy detected a strong echo with clear boundaries covering the lower echo, and computed tomography examination revealed calcification. Both patients underwent surgery, and histopathological evaluation of the mass showed osseous choristoma. They were treated by excision and subsequently cured. CONCLUSION: Osseous choristomas are usually asymptomatic. Our patients were cured immediately after surgery, suggesting that surgical treatment is an effective strategy.

Application and Evaluation of an Independent Robotic Arm System in K-wire Placement for Lumbar Fusion.

STUDY DESIGN: A single-center randomized controlled study. OBJECTIVE: The objective of this study was to introduce a novel robotic system with an independent arm ("Orthbot Intelligent Orthopedic Minimally Invasive System"; Xin Junte Surgical Technologies) that has been developed and tested as a surgical assistant for autoplacement of the Kirschner wire (K-wire) in lumbar fusion, and to evaluate its accuracy by comparing it with the conventional free-hand instrumentation. SUMMARY OF BACKGROUND DATA: Robotic technology has performed excellently in spine surgeries and has demonstrated high clinical value and potential. Robot-assisted spinal surgery is now being promoted as a paradigm for technology-led advancement. MATERIALS AND METHODS: A total of 24 patients were recruited and assigned randomly to the robotic arm group (RG) or the free-hand group (FG). Deviation distance and deviation angle (DA) of K-wire placement were measured and compared between the RG and the FG. RESULTS: The average deviation distance was 0.88±0.08 mm in the RG and 5.13±1.68 mm in the FG (P<0.001). In both coronal and sagittal radiographs, the average DA of K-wire placement was smaller in the RG (P<0.05), and in both axial and sagittal computed tomography scans, the average DA of pedicle screw placement was also lower in the RG (P<0.05), which indicated higher accuracy of the robotic system. CONCLUSIONS: The novel robotic system in this study has shown certain advantages over the conventional free-hand approach in K-wire placement for lumbar fusion, including being more accurate in K-wire placement, fully automatic, and more adaptive to preoperative plans. Although the robotic arm proves to be promising in our results, the small sample size in this clinical study necessitates further multicenter, large sample follow-up studies to verify its advantages.

Associations Between the Use of Renin-Angiotensin System Inhibitors and the Risks of Severe COVID-19 and Mortality in COVID-19 Patients With Hypertension: A Meta-Analysis of Observational Studies.

Angiotensin-converting enzyme inhibitors (ACEIs) and angiotensin receptor blockers (ARBs) share a target receptor with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The use of ACEIs/ARBs may cause angiotensin-converting enzyme 2 receptor upregulation, facilitating the entry of SARS-CoV-2 into host cells. There is concern that the use of ACEIs/ARBs could increase the risks of severe COVID-19 and mortality. The impact of discontinuing these drugs in patients with COVID-19 remains uncertain. We aimed to assess the association between the use of ACEIs/ARBs and the risks of mortality and severe disease in patients with COVID-19. A systematic search was performed in PubMed, EMBASE, Cochrane Library, and MedRxiv.org from December 1, 2019, to June 20, 2020. We also identified additional citations by manually searching the reference lists of eligible articles. Forty-two observational studies including 63,893 participants were included. We found that the use of ACEIs/ARBs was not significantly associated with a reduction in the relative risk of all-cause mortality [odds ratio (OR) = 0.87, 95% confidence interval (95% CI) = 0.75-1.00; I 2 = 57%, p = 0.05]. We found no significant reduction in the risk of severe disease in the ACEI subgroup (OR = 0.95, 95% CI = 0.88-1.02, I 2 = 50%, p = 0.18), the ARB subgroup (OR = 1.03, 95% CI = 0.94-1.13, I 2 = 62%, p = 0.48), or the ACEI/ARB subgroup (OR = 0.83, 95% CI = 0.65-1.08, I 2 = 67%, p = 0.16). Moreover, seven studies showed no significant difference in the duration of hospitalization between the two groups (mean difference = 0.33, 95% CI = -1.75 to 2.40, p = 0.76). In conclusion, the use of ACEIs/ARBs appears to not have a significant effect on mortality, disease severity, or duration of hospitalization in COVID-19 patients. On the basis of the findings of this meta-analysis, there is no support for the cessation of treatment with ACEIs or ARBs in patients with COVID-19.

Using copper sulfide nanoparticles as cross-linkers of tumor microenvironment responsive polymer micelles for cancer synergistic photo-chemotherapy.

Photo-chemotherapy presents promising therapeutic effects in cancer treatment. Photo-thermal and chemotherapeutic agents are generally delivered independently or jointly by drug carriers, such as polymer micelles. A polymer micelle is one type of widely researched drug carrier. However, there is a disassembly risk for polymer micelles under excessive dilution in blood circulation, leading to the premature release of payloads from the micelles and finally resulting in undesirable toxic side effects. Herein, amino-PEG decorated copper sulfide nanoparticles (CuS NPs) with photothermal effect were applied as a cross-linker to enhance polymeric micelles' stability and to provide photothermal therapy in the meanwhile. The micelles were prepared using a pH/reductive responsive polymer, poly(ε-caprolactone)-ss-poly(2-(diisopropylamino)ethyl methacrylate/glycidyl methacrylate/2-methylacrylloxyethyl phosphorylcholine (PCL-SS-P(DPA/GMA/MP)), abbreviated as DGM. Cross-linked micelles (DGM-CuS) exhibited high photothermal transformation efficiency and excellent stability against dilution, as well as pH and redox responsive drug release. Under near-infrared laser irradiation, the cell cytotoxicity of doxorubicin-loaded micelles DGM-CuS@DOX and DGM-CuS@DOX-P (DGM-CuS@DOX modified by peptides) increased by 17.1 times and 69.2 times correspondingly compared to that without laser irradiation. All of the solid 4T1 tumors disappeared, and tumor metastases were merely observed in the major organs of the tumor-bearing mice after administration of DGM-CuS@DOX and DGM-CuS@DOX-P with irradiation. In this synergistic therapy system, CuS NPs play double roles of a photothermal agent and a micelle cross-linker. The strategy of utilizing nanoparticles as cross-linkers is newly reported, which offers new insight for combination therapy.

Systemic lupus erythematosus and risk of sexual dysfunction: A systematic review and Meta-Analysis.

OBJECTIVE: To systematically review and summarize the available literature regarding the association between systemic lupus erythematosus (SLE) and sexual dysfunction (SD) in both sexes. METHODS: We retrieved relevant studies from the following databases: PubMed, Embase,Cochrane Library, and Web of Science. Two reviewers independently reviewed the studies in our sample, assessed their validity, and extracted relevant data. Sensitivity and subgroup analyses were performed to distinguish sources of heterogeneity. RESULTS: Our search resulted in a sample of eight eligible studies, which involved 758 patients in the SLE group and 1724 individuals in the control group. The pooled RR for the increased risk for SD compared to those in the control group was 1.80 (95%CI 1.12-2.87). Subgroup analysis by sex revealed that males (pooled RR = 2.98, 95%CI 2.41-3.68) had a higher risk of SD compared to females (pooled RR = 1.56, 95%CI 0.99-2.48). Females with SLE had significantly lower values in FSFI compared to the healthy individuals (WMD=-0.224, 95%CI -0.441 to -0.078). Age of participants and the quality of studies might influence the results. CONCLUSIONS: Our meta-analysis suggests that SLE is significantly associated with an increased risk of sexual dysfunction. It is of great urgency to implement for active interventions that aimed to treat or prevent SD among SLE patients.

Evaluation of a new spinal surgical robotic system of Kirschner wire placement for lumbar fusion: A multi-centre, randomised controlled clinical study.

BACKGROUND: To introduce a novel robotic system 'Orthbot' that has been developed and tested as a surgical assistant for auto-placement of the K-wire in lumbar fusion. METHODS: This is a multi-centre, randomized controlled clinical study that includes 56 patients (robot group, RG: 27, free-hand group, FG: 29). Following the pre-operative planning and intra-operative fluoroscopic images, the 'Orthbot' automatically completed registration and K-wire placement under the supervision of the surgeon. Deviation distance (DD) and deviation angle (DA) were used as the primary parameters to evaluate the accuracy of the robotic system. RESULTS: The average DD was 0.95 ± 0.377 mm and 4.35 ± 2.01 mm, respectively in the RG and FG (p < 0.001). The average DA of the K-wire in the coronal plane and the sagittal plane in X-Ray was respectively 6.80 ± 7.79° and 1.27 ± 2.32° in the RG (p < 0.001), and 22.22 ± 16.85° and 4.57 ± 3.86° in the FG (p < 0.001), which showed a higher accuracy rate in the robotic-assisted cases compared to the free-hand cases. CONCLUSIONS: The novel robotic system could achieve accurate K-wire insertions as indicated by the radiological results.

Antenatal corticosteroids administration on mortality and morbidity in premature twins born at 25∼34 gestational weeks: A retrospective multicenter study.

OBJECTIVE: To evaluate the effects of antenatal corticosteroids (ACS) administration on mortality and major neonatal complications in early life of preterm twins. STUDY DESIGN: This study retrospectively enrolled 1 662 twins delivered at 25∼34+6gestational weeks in China from January 2013 to December 2014. They were divided into ACS group and no-ACS group according to weather their mothers received ACS or not. Moreover, they were subgrouped as 25∼27+6 and 28∼34+6gestational week groups. Multivariable logistic regression was used to analyze the effects of ACS on the incidence of mortality and major morbidities. RESULTS: A total of 910 neonates (54.8 %) received one or more doses of ACS, and 752 neonates (45.2 %) did not receive any ACS. No significant difference in infant mortality was observed between the ACS and no-ACS groups (P = 0.321). The ACS group had decreased incidence of respiratory distress syndrome (RDS) and mild RDS compared with the no-ACS group (both P < 0.05). There were no significant differences in the incidence of bronchopulmonary dysplasia, intraventricular hemorrhage, necrotizing enterocolitis, retinopathy of prematurity, patent ductus arteriosus, sepsis and severe RDS between the two groups (all P > 0.05). The subgroup analysis showed that the incidence of RDS was lower in the ACS group than in the no-ACS group (P = 0.036) at 28∼34+6weeks. However, the incidence of mild ROP was higher in the ACS group than that in the no-ACS group (P = 0.047) at 25∼27+6 weeks. Multivariable logistic regression analysis demonstrated a decreasing risk of RDS (aOR = 0.661, 95 %CI:0.506-0.863, P = 0.002) after adjusting the gestational week, birth weight, small for gestational age, delivery mode, 5 min Apgar score, and maternal perinatal complications. CONCLUSION: In twin preterm infants, ACS administration is associated with a reduced risk of RDS. However, our data suggest that it may not have a beneficial effect on mortality and other short-term morbidities.

Numerical Simulation of Polymer Dispersion Systems for Polymer Injection on Offshore Platforms.

Because of the limited space and high cost of offshore platforms, the dispersion and dissolution of the polymer are required to be of high efficiency, which is essential for polymer injection to enhance hydrocarbon recovery. The numerical simulation models of the water-powder mixing process by Venturi jetting and air-mixing were established. The multiphase flow fields in the water jet ejector, water-powder mixing head, and stirring tank were numerically simulated by FLUENT. Then, the distributions of velocity, volume fraction, pressure, and turbulent kinetic energy of each phase were obtained to evaluate the effects of polymer dispersion and the dissolution of the two mixing methods. According to the maximum velocity of the mixture at the Venturi jet, the optimized length of the throat is 25 mm in our models. The results of the air-mixing process show that a 120° angle of support rods has the best effect of water-powder mixing. The results of the present study show that compared with air-mixing, the combination of Venturi jet and the stirring tank can obtain a broader agitation range and more extensive effect on the flow field, which could uniformly disperse the polymer powder into water. This study has a guiding significance for the design of the onsite polymer injection process.