Co-adsorption behavior of aggregated asphaltenes and silica nanoparticles at oil/water interface and its effect on emulsion stability

In petroleum industry, crude oil emulsions are commonly formed in oilfields. The asphaltenes and fine particles in crude oil may affect the stability of the emulsions by adsorbing at the water/oil interface. In this research, the effect of silica nanoparticles and asphaltenes on emulsion stability is explored first. The asphaltenes are proved to benefit emulsion stability. Unlike the asphaltenes, however, the modified silica nanoparticles may have positive or negative effect on emulsion stability, depending on the asphaltene concentration and aggregation degree in the emulsions. Further, it is confirmed by conducting interfacial experiment that the asphaltenes and particles can adsorb at the interface simultaneously and determine the properties of the interfacial layer. More in-depth experiments concerning contact angle and asphaltene adsorption amount on the particles indicate that the asphaltenes can modify the wettability of the particles. Higher concentration and lower aggregation degree of the asphaltenes can increase their adsorption amount on the surface of particles and then improve the modification effectiveness of the particles. Resultantly, the particles with good modification effectiveness can enhance the emulsion stability while the particles with poor modification effectiveness will weaken the emulsion stability.

Effects of the urban landscape on heatwave-mortality associations in Hong Kong: comparison of different heatwave definitions

Despite increased attention given to potential modifiers of temperature-mortality associations, evidence for variations between different urban landscape characteristics remains limited. It is in this context that in this paper effect modifications of multiple urban landscape characteristics are explored under different heatwave definitions for different age groups and gender in Hong Kong, China. Daily meteorological data and heatwave-related mortality counts from 2008 to 2017 were collected from the Hong Kong Census and Statistics Department, China. A case-only design was adopted, combined with logistic regression models to examine the modification effects of five urban landscape characteristics under six heatwave definitions. Stratified analyses were conducted to investigate age- and gender-specific effect modifications. It is found that individuals living in greener areas experienced lower levels of mortality during or immediately after heatwaves. In contrast, a higher building density and nighttime land surface temperature (LST) were associated with a higher heatwave-related mortality risk. Pronounced effect modifications of these urban landscape characteristics were observed under hotter and longer heatwaves, and in older adults (age ≥ 65 years) and males. The findings provide a scientific basis for policymakers and practitioners when considering measures for coping with hotter, longer, and more frequent heatwaves in the context of global climate change.

Microstructure and Mechanical Properties of Poly (Vinyl Chloride) Modified by Silica Fume /Acrylic Core-Shell Impact Modifier Blends

This research explored replacing acrylic core-shell impact modifier （AIM） by silica fume to toughen PVC. 100%, 75%, 50% and 25% of AIM （8 phr） were substituted by silica fume in PVC respectively, and then processed by dry blending and twin-screw extrusion. Severe silica fume agglomeration was observed by scanning electron microscope （SEM） in the PVC matrix when 8 phr pure silica fume was used and processed by screw speed of 20 rpm. Its tensile strength was thereby reduced by 38% comparing to unmodified PVC. The silica fume was successfully dispersed while the screw speed was slowed down to 10 rpm to give a stronger screw torque and a longer melt residential time in the extruder. The tensile strength was ’recovered’ to a level comparable to unmodified PVC. Impact test were performed on all formulations extruded at 10 rpm screw speed and synergetic toughening effect was found with 50% substitution and it had the impact strength that was comparable to 8 phr pure AIM toughened PVC.

Family history of esophageal cancer modifies the association of serum lipids and malignant esophageal lesions:a nested case-control study from the"Endoscopic Screening for Esophageal Cancer in China"trial

Background:The association of lipids and cancer has varied greatly among different cancer types,lipid components and study populations.This study is aimed to investigate the association of serum lipids and the risk of malignant lesions in esophageal squamous epithelium.Methods:In the"Endoscopic Screening for Esophageal Cancer in China"(ESECC)trial,serum samples were collected and tested for total cholesterol(TC),triglycerides,low-density lipoprotein cholesterol(LDL-C),and high-density lipoprotein cholesterol at the time of subject enrollment.Cases were defined as malignant esophageal lesions identified by baseline endoscopic examination or by follow-up to May 31,2018.Controls were randomly selected using incidence density sampling in the same cohort.Conditional logistic models were applied to identify the association of serum lipids and the risk of malignant esophageal lesions.Effect modification was evaluated by testing interaction terms of the factor under assessment and these serum lipid indicators.Results:No consistent association between serum lipid levels and esophageal malignant lesions were found in a pooled analysis of 211 cases and 2101 controls.For individuals with a family history of esophageal cancer(EC),high TC,and LDL-C were associated with a significantly increased risk of having malignant lesions(odds ratio[OR]Highvs.Low TC=2.22,95%confidence interval[CI]:1.14-4.35;ORHighvs.Low LDL-C=1.93,95%CI:1.01-3.65).However,a negative association was observed in participants without an EC family history(ORHighvs.Low TC=0.69,95%CI:0.48-0.98,Pinteraction=0.002;ORHighvs.Low LDL-C=0.50,95%CI:0.34-0.76,Pinteraction<0.001).Conclusions:In this study,we found that the association of serum lipids and malignant esophageal lesions might be modified by EC family history.The stratified analysis would be crucial for population-based studies investigating the association of serum lipids and cancer.The mechanism by which a family history of EC modifies this association warrants further investigation.