Association of choroidal thickness with early stages of diabetic retinopathy in type 2 diabetes

AIM: To assess the correlation between choroidal thickness (CT) and the early stages of diabetic retinopathy (DR) in type 2 diabetic patients. METHODS: We divided 83 diabetic patients (51-80 years of age; 50 females) into non diabetic retinopathy group (NDR) and mild/moderate nonproliferative diabetic retinopathy (NPDR) group, and compared them with 26 non-diabetic control subjects (51-78 years of age; 16 females). Subfoveal choroidal thickness (SFCT) and parafoveal choroidal thickness (PFCT) were measured using enhanced depth imaging spectral-domain optical coherence tomography (EDI-OCT). Ocular health status, disease duration, body mass index, and hemoglobin A1c (HbA1c) were recorded. RESULTS: The mean ages of the NDR, NPDR, and control groups were 68.0±6.9y, 67.8±6.4y, and 65.1±6.3y, respectively (P=0.17). Pearson correlation of the right and left eyes for the control subjects was 0.95 and for the NDR subjects was 0.93. SFCT for the right eyes of the controls was 252.77± 41.10 μm, which was significantly thicker than that of the right eyes in NDR group (221.51±46.56 μm) and the worse eyes of the NPDR group (207.18±61.87 μm; ANOVA, P<0.01). In the diabetic patients pooled together, age was the only variable significantly associated with SFCT (multiple linear regression analysis, P=0.01). CONCLUSION: CT decreased significantly in the NDR and mild/moderate NPDR eyes compared with the control eyes. Age is significantly associated with SFCT in the diabetic patients. Diabetic choroidopathy may be present before clinical retinopathy

Numerical Analysis on the Influence of Thermal Effects on Oil Flow Characteristic in High-Pressure Air Injection (HPAI) Process

In previous laboratory study, we have shown the thermal behavior of Keke Ya light crude oil (Tarim oilfield, branch of CNPC) for high-pressure air injection (HPAI) application potential study. To clarify the influences of thermal effects on oil production, in this paper, we derived a mathematical model for calculating oil flow rate, which is based on the heat conduction property in porous media from the combustion tube experiment. Based on remarkably limited knowledge consisting of very global balance arguments and disregarding all the details of the mechanisms in the reaction zone, the local governing equations are formulated in a dimensionless form. We use finite difference method to solve this model and address the study by way of qualitative analysis. The time-space dimensionless oil flow rate (qD) profiles are established for comprehensive studies on the oil flow rate characteristic affected by thermal effects. It also discusses how these findings will impact HPAI project performances, and several guidelines are suggested

The Feasibility of CO₂ and N₂ Injection for the Tahe Fracture-Cavity Carbonate Extra-Heavy Oil Reservoir: An Experimental Study

The Tahe Ordovician carbonate reservoir is special and unique, with its fracture and cavity serving as both pathway and crude oil storage space. Additionally, its extra-heavy crude oil is highly viscous and dense. The combination of all these characteristics leads to considerable challenges in the development of the Tahe extra-heavy oil reservoir. Due to the inelasticity of various enhanced oil recovery methods, in the study presented in this paper, CO2 and N2 were chosen as the displacing medium for the investigation of gas flooding feasibility for the Tahe carbonate extra-heavy oil reservoir. The results of physical modeling experiments showed that for Tahe crude oil, the CO2 possessed excellent solubility and viscosity reduction rate under high pressure and temperature conditions. The N2 had less influence on the extra-heavy oil than the CO2. For CO2, dissolution and extraction were the important displacement mechanisms. However, in the fracture-cavity core, high pressure caused gas breakthrough channels to form easily. The produced oil possessed better quality due to the asphaltene and resin deposition, and the CO2 was able to continue extracting light hydrocarbon along with the gas breakthrough channel. For N2, pressure maintenance was the major displacement mechanism. Due to its low solubility and extraction ability, the N2 caused gas breakthrough more easily than the CO2. The serious overlap effect reduced the gas sweep efficiency and led to the lower cumulative recovery