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The incidence of in-hospital death in acute myocardial infarction (AMI) is high, which seriously threatens the life and health of patients. At present, many countries and regions have established a variety of objective assessment models for predicting the in-hospital mortality of patients with AMI, providing important decision-making support for patients with different risk levels when formulating treatment plans. With the rise of artificial intelligence, many new modeling methods also show certain advantages over the traditional models. This article systematically introduces the commonly used and newly constructed risk prediction models for in-hospital mortality of AMI, in order to provide help for medical staff to assist decision-making in clinical practice, and provide reference for the establishment of a safe and more effective risk prediction model in the future.

The Pearl River Delta (PRD) is an extremely complex, large-scale estuary system in China. In this study, a long-term process-based morphodynamic model was developed to investigate the characteristics of variations in energy flux and dissipation and their evolution alongside the hydrodynamic and topographic evolution of the PRD since the Holocene transgression maximum. The results show that the evolution of the dynamics and topography of the PRD are largely influenced by the geological and geomorphological structures of the region. Energy flux and dissipation in the inner estuary exhibited a patchy distribution, with areas of high energy flux appearing in deep troughs, near headlands, and in gorges containing bedrock islands, and areas of relatively small energy flux appearing in the flow shadow zones of the islands, tidal fluctuation confluence area, and shoals. Corresponding to the energy flux distribution, sediment accumulation also exhibited a high degree of spatial and temporal variability. The evolution of the coastline of the PRD is not driven from north to south, or from the river outlet to the downstream area. Rather, multiple deposition bodies simultaneously developed in the north and south without overlapping. With the deposition of sediment in the estuary, the isoamplitude lines of tidal waves were gradually extrapolated and the spatial distribution gradually shifted from the northwest to the southwest. This indicates the mutual transformation between the estuarine river and tidal power, and also reflects the development characteristics of the river system.

A new Zn(II)-containing coordination complex [ZnBrL] (1) based on the Schiff base ligand(E)-1-(((3-(piperidin-1-yl)propylidene)amino)methyl)naphthalen-2-ol (HL) has been successfully prepared using...

To find the effect of Paris saponin VII (PS VII)‐mediated PI3K/AKT/MAPK signaling pathway on the sensitivity of ADR‐resistant HepG2 cell (HepG2/ADR) cells to ADR. The proliferation inhibitory rates were detected by using MTT assay. Flow cytometry was employed to examine the intracellular accumulation of ADR. The expressions of drug‐resistant genes (P‐gp, MRP and BCRP) were detected by qRT‐PCR, cell apoptosis by Annexin‐V‐FITC/PI staining, and the expressions of drug‐resistance‐related proteins, apoptosis‐related proteins, and PI3K/AKT/MAPK pathway‐related proteins were determined by Western blotting. HepG2/ADR and HepG2 cells treated with PS VII (0.88, 1.32, 1.98, and 2.97 μM) for 48 hours showed increased proliferation inhibitory rate in a dose‐dependent manner. HepG2/ADR cells treated PS VII (0.88, 1.32, 1.98 μM) for 48 hours showed decreased IC50 of ADR. Compared with HepG2/ADR cells treated with ADR (5 nM), those treated with PS VII (≤1.98 μM) and ADR (5 nM) showed enhanced ADR accumulation, decreased drug‐resistant gene expressions, increased cell apoptosis with unregulated Bax and cleaved caspase‐3 and downregulated Bcl‐2, as well as the inhibition of PI3K/AKT/MAPK pathway. Moreover, the combination of ADR (5 nM), PS VII (1.98 μM), and LY294002 (PI3K/AKT inhibitor, 20 μM)/SB203580 (P38 inhibitor, 20 μM) for 48 hours could further decreased the HepG2/ADR cell viability, but induced cell apoptosis, accompanying with the decreased expressions of drug‐resistant genes. PS VII could downregulate the expressions of drug‐resistance genes, increase intracellular accumulation of ADR, promote cell apoptosis, and enhance the sensitivity of HepG2/ADR cells to ADR via PI3K/AKT/MAPK.

A structure does not reach a stable state during the construction process, and hence its structural reliability is low. In order to ensure the safety of the construction process and final structural quality, it is necessary to analyze the safety and structural mechanical properties of large-span space steel structures during the construction process. Based on the engineering background of the polyline symmetrical large-span steel structure construction process, this research established a finite element model of the large-span steel structure on an ANSYS platform. The correctness of the model was verified by comparing the measured frequency of the large-span steel structure with the frequency calculated in the finite element model. Based on the life-death element method, the internal force and deformation response characteristics of the large-span steel structure in the construction process were analyzed, and the different effects of the on-time completion and step-by-step construction on the performance of the broken-line large-span steel structure were compared and analyzed. The study found that the long-span steel truss structure is more sensitive to the construction process, and the final forming state is greatly affected by the construction process. The construction sequence is different, and the structure process and size and distribution of the final stress and deformation are also different. The analysis result of the construction process is closer to that of the actual project. Therefore, appropriate construction paths should be used in the construction process to reduce the impact of path effects on structural performance. It is recommended to pay more attention to the displacement and stress response of the truss when it encounters similar a symmetrical long-span steel structure truss in-place of the forming construction.

The dose-response association between cardiorespiratory fitness and risk of atrial fibrillation (AF) is still not well known. Therefore, we performed a comprehensive meta-analysis to investigate the dose-response association between cardiorespiratory fitness and incident AF. We performed a comprehensive search in the databases of PubMed, Cochrane library, and Ovid from inception through August 2019. A one-stage robust error meta-regression method was used to summarize the dose-response association between cardiorespiratory fitness and AF. A total of 9 studies were included in this meta-analysis. In the categorical analysis, compared with the lowest level of cardiorespiratory fitness, both the intermediate (RR = 0.68, 95% CI 0.57-0.82) and highest (RR = 0.60, 95% CI 0.51-0.72) levels of cardiorespiratory fitness were associated with a decreased risk of AF. In the dose-response analysis, per 1 metabolic equivalent increase in cardiorespiratory fitness was associated with a decreased risk of AF (RR = 0.91, 95% CI 0.86-0.95). There was an inverse relationship between cardiorespiratory fitness and risk of AF with evidence of linearity (Pnon-linearity = 0.43). Current evidence suggests that there is an inverse relationship between cardiorespiratory fitness and risk of AF, manifesting as a higher level of cardiorespiratory fitness is associated with a decreased risk of AF.

A high power light-emitting diodes (LED) light source, which is assembled by many LED chips and heat sink, has a not uniform temperature distribution at working condition. Analysis and prediction of a high-power LED system lifetime are complicated and time-consuming.In this study, two artificial neural networks (ANN) are employed to simplify the LED lighting system’s lifetime prediction and increase the precision of such analysis. The temperature distribution of the high power light source is calculated by Finite element method (FEM) with LED chip photo-electro-thermal (PET) ANN. With the precise LED temperature distribution, the lifetime for multi-chip high-power LED light source can be predicted by lifetime ANN.The PET ANN is used to simplify the multi-physics coupling in LED PET analyzing. The lifetime ANN can predict the lifetime of a LED chip across a wide range of temperatures and not merely corresponding to several testing and interpolation points.This work aims to rapidly analyze multi-chip high-power lighting systems characteristics. The repeated tests and calculations of PET and lifetime are avoided with this method. This approach presents a new and effective way to assess the reliability of high-power LED light source. Keywords: Artificial neural network (ANN), Light-emitting diodes (LED), Lifetime prediction, Photo-electro-thermal (PET) multiphysics coupling

MicroRNAs (miRNAs) belong to the subgroup of small noncoding RNAs, which typically serve as important gene regulators to participate in different biological events, such as tumor cell growth and apoptosis. Recent studies indicated microRNA-4651 (miR-4651) was involved in hepatocellular carcinoma (HCC) progression. The certain role of miRNA-4651 during the progression of HCC, however, remains unclear. Herein, we investigated the mRNA expression level of miR-4651 in HCC tissues and HCC cell lines and found miR-4651 was noticeably down-regulated compared with the normal liver tissues and QSG-7701 cell line, respectively. Then, miR-4561 overexpression obviously repressed the proliferation and promoted apoptosis in two HCC cell lines. Interestingly, we further identified that miR-4561 could directly interact with FOXP4 in HCC cells by using bio-informatic method and report assay. Moreover, forced expression of FOXP4 showed an opposite effect compared with miR-4561 in HCC cell lines. Hence, our findings strongly indicated that miR-4561 regulated the HCC cell growth and apoptosis mainly through targeting the FOXP4 genes. Clinically, the miR-4561/FOXP4 axis might be a potential target for therapeutic application of HCC patient treatment.

Objectives : To assess the predictive function of miR-21 rs1292037 A greater than G polymorphism in survival and ischemia-reperfusion injury (IRI) in hepatocellular carcinoma (HCC) patients. Methods : Th e experiment was carried out between July 2018 and July 2019, whereas the prospective clinical study was carried out between January 2014 and January 2019. In this study, 62 HCC patients with hepatitis B virus (HBV), 17 HCC patients without HBV, and 13 healthy controls were investigated. Micro-RNA-21 levels in the blood were identified using quantitative reverse-transcription polymerase chain reaction (qRT-PCR) and allele specific PCR for miR-21 rs1292037. Partial hepatectomy was performed in all patients, and the tumor development indicators and survival time were evaluated in a subsequent follow-up. Cell-based simulated IRI model of HCC huh7 cell line was used to determine the functions of miR-21 with respect to IRI and proliferation. Results : Micro-RNA-21 levels were significantly increased in HCC patients. Furthermore, an miR- 21 rs1292037 A greater than G polymorphism was found to be significantly associated with HCC prognosis and severity of liver injury after hepatectomy. In vitro study revealed that miR-21 might prevent IRI from occurring, and can induce proliferation in HCC huh7 cells. These functions of miR-21 were demonstrated to be triggered by IL-12A inhibition. Conclusion : Micro-RNA-21 rs1292037 A greater than G polymorphism can predict IRI and tumor progression by regulating the miR-21/IL-12A.axis. Saudi Med J 2020; Vol. 41 (4): 383-392 doi: 10.15537/smj.2020.4.24994 How to cite this article: Wu C, Tang G, Wang X, Zhang J, Chen S, Lu C, Zhang D, Li Y. Micro-RNA-21 rs1292037 A>G polymorphism can predict hepatocellular carcinoma prognosis (HCC), and plays a key role in cell proliferation and ischemia-reperfusion injury (IRI) in HCC cell model of IRI. Saudi Med J 2020; Vol. 41 (4): 383-392. doi: 10.15537/smj.2020.4.24994

In a million-scale host-scale environment, the resource scheduling/management system becomes more and more important. How to improve resource utilization and reduce the cost of infrastructure while ensuring the performance of business operations in the data center is the core issue we must consider. And because of the complex relationship between tasks, the corresponding DAG (DAG: Directed Acyclic Graph) is often formed, making the distribution and management of tasks and resources more difficult. In order to solve the problems of tedious task scheduling and low resource utilization in a large-scale host machine environment, this article describes a general task and machine model based on the actual situation of various companies, and based on this model, implements a model suitable for massive data task scheduling scheme.

For large-scale AI training, the manual allocation of GPU resources is too inefficient, and it faces the problems of task allocation and fault restart. In this paper, a fully automatic machine learning platform is designed, which manages server resources uniformly, and users describe the required resources through configuration files. The platform automatically performs AI task allocation and scheduling based on the cluster load, which solves the problems of low cluster resource utilization and uneven machine load distribution. The platform also provides an automatic release and continuous integration of the model, which greatly simplifies the configuration of the model's operating environment and external release process, enabling researchers to focus more on model adjustments. Finally, it is verified by experiments that the extra time spent on AI task training through this platform is negligible, which confirms the feasibility of the platform.

Carbon nitride (CNx) films supported on fluorine-doped tin oxide (FTO) glass are prepared by radio frequency magnetron sputtering, in which the film thicknesses are 90â100 nm, and the element components in the CNx films are in the range of x = 0.15â0.25. The as-prepared CNx is for the first time used as counter electrode for dye-sensitized solar cells (DSSCs), and show a preparation-temperature dependent electrochemical performance. X-ray photoelectron spectroscopy (XPS) demonstrates that there is a higher proportion of sp2 Cî…C and sp3 Cî¸N hybridized bonds in CNx-500 (the sample treated at 500 °C) than in CNx-RT (the sample without a heat treatment). It is proposed that the sp2 Cî…C and sp3 CâN hybridized bonds in the CNx films are helpful for improving the electrocatalytic activities in DSSCs. Meanwhile, Raman spectra also prove that CNx-500 has a relatively high graphitization level that means an increasing electrical conductivity. This further explains why the sample after the heat treatment has a higher electrochemical performance in DSSCs. In addition, the as-prepared CNx counter electrodes have a good light transmittance in the visible light region. The results are meaningful for developing low-cost metal-free transparent counter electrodes for DSSCs. Keywords: Solar cells, Counter electrodes, Carbon nitride, Electrocatalysis, Magnetron sputtering

The role of non-vitamin K antagonist oral anticoagulants (NOACs) in stroke prevention remains unclear in Asian patients with atrial fibrillation (AF). Therefore, we performed a meta-analysis to compare the efficacy and safety outcomes of NOACs in Asian patients with AF from the real-world settings. The PubMed and Embase databases were systematically searched to identify eligible observational studies until June 2019. The odds ratios (OR) and 95% confidence intervals (CIs) were calculated and then pooled by a random-effects model. A total of 18 observational studies were included. Compared with warfarin, dabigatran (OR, 0.56, 95% CI 0.43-0.73), rivaroxaban (OR, 0.54, 95% CI 0.44-0.67), apixaban (OR, 0.41, 95% CI 0.35-0.48), and edoxaban (OR, 0.19, 95% CI 0.14- 0.25) reduced the risk of major bleeding, while dabigatran (OR, 0.78, 95% CI 0.71-0.85), rivaroxaban (OR, 0.74, 95% CI 0.68-0.82), and edoxaban (OR, 0.29, 95% CI 0.22-0.39) were associated with reduced risks of stroke or systemic embolism. In addition, dabigatran versus apixaban was associated with increased risks of ischemic stroke and gastrointestinal bleeding, while rivaroxaban versus apixaban was associated with elevated risks of stroke or systemic embolism, ischemic stroke, intracranial hemorrhage, and gastrointestinal bleeding. In Asian patients with AF, NOACs are non-inferior to warfarin for stroke prevention, and apixaban may be a better choice compared with dabigatran or rivaroxaban.

Background Hepatocellular carcinoma (HCC) is one of the common lethal types of tumors all over the world. Overexpression of mircoRNA-224 (miR-224) has been reported to act as a potential biomarker for HCC patients. The goal of our study was to assess the prognostic impact of the expression and polymorphism of miR-224 in hepatitis B virus (HBV)-related hepatocellular carcinoma (HCC) patients after liver resection. Methods A total of 62 cases of HBV-positive HCC patients, 17 HCC patients without HBV, and 13 healthy cases were enrolled in this study. Blood leukocyte miR-224 level were determined by qRT-PCR. Genotyping analysis of miR-224 rs188519172 was performed using an allele-specific PCR assay. All patients were undergoing partial liver resection and the prognostic values of miR-224 rs188519172 polymorphism for tumor development, survival rate, and liver injury after liver resection were examined. Results When we compared the blood leukocyte miR-224 level between HCC patients and healthy cases, we found that it was significantly increased in HCC patients. By subgroup analysis, it demonstrated that miR-224 expression was significantly increased in the HBV positive group compared with the HBV negative group. miR-224 rs188519172 AG + GG phenotype was significantly associated with severe liver injury after liver resection and patients carrying miR-224 rs188519172 AG + GG phenotype have a higher risk of cirrhosis and lower overall and disease-free survival rate. Meanwhile, the combination of miR-224 rs188519172 AG + GG phenotype and AFP value could improve the prognosis assessment of HBV related HCC. Conclusions miR-224 rs188519172 polymorphism is an indicator of liver injury and a novel prognostic biomarker for tumor development and survival of HBV related HCC patients after liver resection.

Delta progradation and sediment flux of the Pearl River Delta (PRD), southern China, during the Holocene are presented based on analyses of borehole data on the delta plain. Results indicate that the delta prograded into the drowned valley because of early Holocene inundation from 9 to 6 cal ka BP, as sea-level rise decelerated. The sea level reached its present level at about 6 cal ka BP and, as a consequence, a large portion of the drowned valley was covered by the estuary, with more than 160 rock islands and platforms. The scattered landmasses promoted active deposition and acted as deposition nuclei during deltaic evolution. Consequently, apart from exhibiting a general tendency towards progression, PRD development occurred less regularly over time and space because of deposition around island boundaries. During the last 2 ka, mainly because of significantly increased human activities, which have trapped sediments in the encircled tidal flats along the front of delta plains, the shoreline has advanced rapidly. Estimated sediment fluxes for the three periods (9-6, 6-2 and 2-0 cal ka BP), based on the sediment volume analysis, were 17-25, 22-30 and 44-58 million t a(-1), respectively. Copyright (C) 2016 John Wiley & Sons, Ltd.

Background/Aims: The purpose of this study is to explore the expression characteristics of lncRNA NEAT1 in hepatocellular carcinoma (HCC) and the molecular mechanism of its regulation on sorafenib resistance. Materials and Methods: This experimental study was performed from June 2013 to June 2019. The level of NEAT1 was determined using RT-PCR in HCC and matched adjacent tissues from 79 HCC patients in Linyi central hospital. The patients were divided into two groups to compare their prognosis based on the median NEAT1 expressions as a cutoff value. HCC cell line HepG2 negative control (HepG2-NC), sorafenib-resistant HepG2 cells (HepG2-SR) were transfected with or without NEAT1 siRNA, followed by subsequent molecular analysis, to determine the function of NEAT1 on sorafenib resistance in HCC cells. The cell transcripts were determined by RNA-sequencing analysis. The binding site of the NEAT1 and microRNA-149-5p (miR-149-5p) was verified by luciferase assay. Results: We found that NEAT1 was significantly increased in HCC tissues. Furthermore, NEAT1 expressions were significantly associated with HCC prognosis and chemoresistance patterns against sorafenib. Subsequently, the sorafenib-resistant HCC cell lines, together with the controls, were used to determine the regulatory effect of NEAT1 on HCC cells' progression and sorafenib resistance. NEAT1 targets the miR-149-5p, and therefore, decrease the activity of sorafenib against HCC cells. NEAT1 functions were demonstrated to be triggered by the regulation of miR-149-5p/AKT1 axis. Conclusions: NEAT1/miR-149-5p/AKT1 pathway-based therapy might be a potential clinical application for HCC patients.

The Zhujiang River (Pearl River) Estuary (ZRE) is a very complicated and large-scale estuarine system in China. It consists of two parts: the river networks and the estuarine bays. Not only is the network system one of the most complicated in the world, but also each estuarine bay has a very special morphodynamic feature due to the geological settings. Morphological boundary conditions have direct effects on the energy dissipation and balance. On the basis of a three-dimensional (3-D) barotropic model whose domain includes the river networks and the estuarine bays, the energy budget is discussed under the influence of topography in the ZRE. The elevation and discharge of this model are validated by the observations collected in July 1999 and February 2001. The results show that (1) the source of energy in the ZRE is mainly generated by tides and river runoffs, which have an obvious seasonal change, and (2) there are some typical hotspots where the energy dissipation is 1–2 orders higher than those in the immediate upstream and downstream sections in the ZRE. These hotspots are linked with the small-scale dynamic structures (SSDS) and morphological units. On the basis of the characteristics of the morphology and the energy dissipation, the hotspots can be categorized into three types: the outlet of the ZRE, the meandering river, the branch and junction.

The Pearl River Delta (PRD) is one of the most complex large-scale estuarine systems in China. A long-term morphodynamic model is developed to simulate the evolution of the PRD and its estuarine system. The driving forces and control factors considered in the model include river discharge, representative tides, and sediment supply from the Pearl River system; sediment compaction; neotectonic movement; and sea-level variation. Core data with 14C dating at 40 locations are used to validate the model output with satisfactory results. New findings on the mid-Holocene evolution of the PRD show that the delta’s chronological and spatial evolution pattern is different from those found in previous studies in several respects. The model confirms that complex morphologies, e.g., rocky islands in shallow estuarine bays, are some of the most important factors affecting the long-term evolution of the PRD.

The Pearl River is the largest river system in south China. The Pearl River estuarine system consists of two parts: the channel network and the estuarine bays. These two parts are connected by rock-bound gorges or ‘men’, which means ‘gate’ in Chinese. During the last transgression, the paleo-bay of the Pearl River estuary was separated into inner- and outer-bays by rocky hills. The water of the bays was linked through a series of rock-bound gorges. These gorges developed into ‘men’ during the delta evolution. Based on in situ hydrographic measurements, analysis of topographic maps and satellite imagery, bore hole records with 14C dating, and application of the long-term morphodynamic model (PRD-LTMM), this paper discusses the morphodynamics of ‘men’ including: (1) the bi-directional jet system associated with ‘men’, (2) the evolution of ‘men’, (3) the convergence of paleo-tidal energy caused by ‘men’, (4) the coupled-development of sub-delta plains and related ‘men’, (5) the effect of ‘men’ on the formation of the channel network. According to this study, the rock-bound outlets of the network system are coincident with the high energy tidal flux during the last 6000 years. The locations and formation of the Pearl River outlets and the channel frame were determined by the geographical setting and the dynamic and sediment environment associated with ‘men’. The dynamic structure of the modern Humen and Yamen are typical bi-directional jet systems. There were a series of paleo bi-directional jet systems in paleo Modaomen estuary. The morphodynamic analysis of ‘men’ is a key issue to reveal the evolution of the Pearl River delta and its estuarine system. The evolution of ‘men’ can be summarized into three major stages: bi-directional jet stage, single directional jet stage and post-‘men’ stage. The present ‘men’ in the Pearl River delta are in different stages of evolution.

The Darss–Zingst peninsula at the southern Baltic Sea is a typical wave-dominated barrier island system which includes an outer barrier island and an inner lagoon. The formation of the Darss–Zingst peninsula dates back to the Littorina Transgression onset about 8,000 cal BP. It originated from several discrete islands, has been reshaped by littoral currents, wind-induced waves during the last 8,000 years and evolved into a complex barrier island system as today; thus, it may serve as an example to study the coastal evolution under long-term climate change. A methodology for developing a long-term (decadal-to-centennial) process-based morphodynamic model for the southern Baltic coastal environment is presented here. The methodology consists of two main components: (1) a preliminary analysis of the key processes driving the morphological evolution of the study area based on statistical analysis of meteorological data and sensitivity studies; (2) a multi-scale high-resolution process-based model. The process-based model is structured into eight main modules. The two-dimensional vertically integrated circulation module, the wave module, the bottom boundary layer module, the sediment transport module, the cliff erosion module and the nearshore storm module are real-time calculation modules which aim at solving the short-term processes. A bathymetry update module and a long-term control function set, in which the ‘reduction’ concepts and technique for morphological update acceleration are implemented, are integrated to up-scale the effects of short-term processes to a decadal-to-centennial scale. A series of multi-scale modelling strategies are implemented in the application of the model to the research area. Successful hindcast of the coastline change of the Darss–Zingst peninsula for the last 300 years validates the modelling methodology. Model results indicate that the coastline change of the Darss–Zingst peninsula is dominated by mechanisms acting on different time scales. The coastlines of Darss and the island of Hiddensee are mainly reshaped by long-term effects of waves and longshore currents, while the coastline change of the Zingst peninsula is due to a combination of long-term effects of waves and short-term effects caused by wind storms.

Thousands of rocky hills and islands scattered in the Pearl River delta plain and the adjacent coastal waters in South China have been or will be acted as deposition nucleus during the evolution process of the delta. The Huangmaohai estuarine complex consists of two of the eight major outlets of the Pearl River estuarine system. Since sea level reached the present level approximately 6000 years ago, especially in the last 250 years, the Huangmaohai estuarine complex has progressed to the sea by filling up the sea inlets formed between these rocky islands and between mainland and islands. This ‘filling up’ process left deep imprints on the long-term morpho-dynamic equilibrium in the estuaries. The present paper reveals that the long-term morpho-dynamic relation originating from this ‘filling up’ process in the Huangmaohai estuarine complex is different from that in many coastal plain estuaries in several aspects: (1) longitudinal variation of estuary width, (2) longitudinal variation of tidal range, (3) unique combination of small-scale dynamic structures, (4) bidirectional jet systems, and (5) velocity field and turbidity maximum.

Illustrated by the Baiteng sea-closure project and using the two-dimensional hydrodynamic model ccost-2d, the simulations and analysis of the hydrodynamic characteristics of estuary before and after the building of the project were given in this paper. The results showed that after the building of the project, the flow velocity nearby Baiteng levee decreased significantly, while the flow velocity in Jitimen channel increased more than double. The tidal ranges changed small and the low water level was elevated by 0.5m in upstream and downstream of Baiteng lake. The high tide water level of upstream Baijiao station rose and downstream Xiaolin station declined. The type of tide changed so greatly that the times of both high and low tide delayed more than 2h, and the curve of lower high water level at Xiaolin station became gentle.

Abstract For a low permeability, water-wet reservoir under water flooding development, quite a large amount of oil remains in the rocks as residual oil while the oil recovered is only 10–30%. The amount of residual oil is far larger than that in the high permeability reservoirs. Research in this article has identified two major causes of this situation. One is due to the lithology of the reservoir. Such influence on residual oil comes fromthe content of medium to fine sand and silt;the granular sizes;the reservoir pore throat sizes; andthe effective fluable pore volume. The four parameters are interdependent, each reflecting one aspect of their relationship to the residual oil. The other is the capillary "entrapping force" in the low permeability reservoir on the residual oil. It is indicated through theoretical calculation that the residual oil saturation rises up as the permeability goes down.