bluuebunny/crossref_metadata_2025 huggingface dataset:
Alkali Co-Solvent Polymer Flooding of High TAN Number Oil: Using Phase Experiments, Micro-Models and Corefloods for Injection Agent Selection
Authors: Schumi Bettina , Clemens Torsten , Wegner Jonas , Ganzer Leonhard , Kaiser Anton , Hincapie Rafael E. , Leitenmüller Verena
Published: April 2019

Chemical Enhanced Oil Recovery leads to substantial incremental costs over waterflooding of oil reservoirs. Reservoirs containing oil with a high Total Acid Number (TAN) could be produced by injection of alkali. Alkali might lead to generation of soaps and emulsify the oil. However, the generated emulsions are not always stable.

Phase experiments are used to determine the initial amount of emulsions generated and their stability if measured over time. Based on the phase experiments, the minimum concentration of alkali can be determined and the concentration of alkali above which no significant increase in formation of initial emulsions is observed.

Micro-model experiments are performed to investigate the effects on pore scale. For injection of alkali into high TAN number oils, mobilization of residual oil after waterflooding is seen. The oil mobilization is due to breaking-up of oil ganglia or movement of elongated ganglia through the porous medium. As the oil is depleting in surface active components, residual oil saturation is left behind either as isolated ganglia or in down-gradient of grains.

Simultaneous injection of alkali and polymers leads to higher incremental oil production in the micro-models owing to larger pressure drops over the oil ganglia and more effective mobilization accordingly.

Core flood tests confirm the micro-model experiments and additional data are derived from these tests. Alkali co-solvent polymer injection leads to the highest incremental oil recovery of the chemical agents which is difficult to differentiate in micro-model experiments. The polymer adsorption is substantially reduced if alkali is injected with polymers compared with polymer injection only. The reason is the effect of the pH on the polymers. As in the micro-models, the incremental oil recovery is also higher for alkali polymer injection than with alkali injection only.

To evaluate the incremental operating costs of the chemical agents, Equivalent Utility Factors (EqUF) are calculated. The EqUF takes the costs of the various chemicals into account. The lowest EqUF and hence lowest chemical incremental OPEX are incurred by injection of Na2CO3, however, the highest incremental recovery factor is seen with alkali co-solvent polymer injection. It should be noted that the incremental oil recovery owing to macroscopic sweep efficiency improvement by polymer needs to be taken into account to assess the efficiency of the chemical agents.
An Efficient Mimetic Finite Difference Method For Multiphase Flow In Fractured Reservoirs
Authors: Zhang Na , Abushaikha Ahmad Sami
Published: April 2019

Modelling fluid flows in fractured reservoirs is crucial to many recent engineering and applied science research. Various numerical methods have been applied, including finite element methods, finite volume methods. These approaches have inherent limitations in accuracy and application. Considering these limitations, in this paper, we present a novel mimetic finite difference (MFD) framework to simulate two phase flow accurately in fracture reservoirs.

A novel MFD method is proposed for simulating multiphase flow through fractured reservoirs by taking advantage of unstructured mesh. Our approach combines MFD and finite volume (FV) methods. Darcy's equation is discreted by MFD method, while the FV method is used to approximate the saturation equation. The resulting system of equations is then imposed with suitable physical coupling conditions along the matrix/ fracture interfaces. This coupling conditions at the interfaces between matrix and fracture flow involve only the centroid pressure of fractures, which brings some simplification in analysis. The proposed approach is applicable for three dimensional systems. Moreover, it is applicable in arbitrary unstructured gridcells with full-tensor permeabilities. Some examples are implemented to show the performance of MFD method. The results showed a big potential of our method to simulate the flow problems with high accuracy and application.
Field Applications of Constrained Multiwell Deconvolution
Authors: Jaffrezic V. , Razminia K. , Cumming J. , Gringarten A. C.
Published: April 2019

Objectives/Scope

This paper applies a new constrained multiwell deconvolution algorithm to two field cases: a gas reservoir with two producers, and an oil reservoir with three producers and one injector. Responses given by the constrained multiwell deconvolution are compared with simulations from history-matched reservoir models.

Methods, Procedures, Process

Permanent downhole pressure gauges are routinely installed in most new wells. The resulting large datasets are usually underexploited, however, because it is near impossible to extract information with conventional techniques in the case of well interferences. Multiwell deconvolution (Levitan, 2006; Cumming et al., 2013) solves this problem by providing constant-rate derivative responses of individual wells as if they were producing alone, and interference effects from any one well to any other. The deconvolved responses have the same durations as the corresponding pressure histories, and show features not visible in any of the test build up or drawdown periods.

Results, Observations, Conclusions

The published multiwell deconvolution algorithms are extensions of the single-well deconvolution algorithm from von Schroeter et al. (2001, 2004), which has become an essential component of the well test analysis toolbox. The Cumming et al. (2013) multiwell deconvolution algorithm has been successfully applied to a North Sea reservoir by Thornton et al. (2015). Multiwell deconvolution, however, is strongly overdetermined and the algorithm may not converge to the true solutions. It may also yield solutions that can reproduce pressure histories equally well while being non-physical. This is especially true when dealing with real field data that may be affected by noise on pressure and rate data. In order to reduce non-uniqueness and ensure physically feasible results, Cumming et al. (2019) incorporated additional constraints on the shapes of the deconvolved derivatives to discourage non-physical solutions. They also introduced additional knowledge on the reservoir, for instance, if it is a closed system, all deconvolved derivatives should tend towards a common unit slope at some future time. They illustrated the application of their enhanced algorithm with synthetic examples with known solutions involving up to nine wells. In this paper, the constrained multiwell algorithm is successfully applied to both a gas and an oil reservoir.

Novel/Additive Information

By extracting well and interwell reservoir signatures, multiwell deconvolution allow identification of compartmentalization or unanticipated heterogeneities very early in field life, making it possible to adjust the field development plan and the locations of future wells. In addition, it can accelerate the history-matching process by doing it on constant rate pressure responses rather than on complex production histories. An added advantage is that the comparison between the model derivatives and the actual deconvolved derivatives enables identification of mismatch causes.
Characterisation and Simulation Insights for Gas Reservoirs with Paleo-Contact
Authors: Taggart Ian
Published: April 2019

Many gas reservoirs at the appraisal stage exhibit evidence of persistent gas saturations below free water levels (FWL's). The amounts of gas contained here may, under some situations, be a sizable fraction of the gas cap volumes. Many engineers appear poorly equipped to include, and model, paleo gas in simulation models. This often results in paleo gas being simply ignored when development plans are being considered. This is unfortunate because paleo gas upon pressure depletion can expand, displacing brine towards well completions. This means that while some additional gas production may occur from the paleo zone, the risk of water production may be significantly underestimated if paleo gas is simply omitted. This work discusses the evidence for paleo gas and shows that it may be described and incorporated in simple simulation models provided the user avoids some common misconceptions. It is demonstrated that under depletion conditions, paleo gas can be entirely visible to material balance pressure responses, while at the same time increasing the risk of produced water volumes. For higher pressure paleo gas reservoirs the common P on Z diagnostic plots can also provide early trends that are frequently misinterpreted. This work quantifies the curvature that can result in such systems, and shows that simulation models inherently predict the expected curvature in P on Z. The approach taken here is by design simplistic and is applicable to scoping evaluations where the paleo gas volumes could be a significant volumetric uncertainty. Where possible, we indicate where additional, or more rigorous, descriptions can be applied.
An Improved Understanding About CO2 EOR and CO2 Storage in Liquid-Rich Shale Reservoirs
Authors: Mahzari Pedram , Oelkers Eric , Mitchell Thomas , Jones Adrian
Published: April 2019

During the past decade, enhanced oil recovery (EOR) by CO2 in shale oils has received substantial attention. In shale oil reservoirs, CO2 diffusion into the resident oil has been considered as the dominant interaction between the CO2 in fractures and the oil in the matrices. CO2 diffusion will lead to oil swelling and improvement in oil viscosity. However, despite two-way mass transfer during CO2 EOR in conventional oil reservoirs, one-way mass transfer into shale oils saturated with live oils is controlled by an additional transport mechanism, which is the liberation of light oil components in the form of a gaseous new-phase. This in-situ gas formation could generate considerable swelling, which could improve the oil recovery significantly. This mechanism has been largely overlooked in the past. This study is aimed to better understand the role of this evolving gas phase in improving hydrocarbon recovery.

Taking account of Bakken shale oil reservoir data, numerical simulations were performed to identify efficiencies of EOR by CO2 at the laboratory and field scales. Equation of state parameters between CO2 and oil components were adjusted to optimize the calculations and a sensitivity analysis was performed to identify the role of gas formation and consequent EOR efficiencies. At the laboratory scale, in-situ gas formation can increase oil recovery by 20% depending on the amount of gas saturation. Also, the CO2 storage capacity of the shale matrix can be enhanced by 25%, due to CO2 trapping in the gas phase. At the field scale, an additional oil recovery of 9.1% could be attained, which is notably higher than previous studies where this gas evolution mechanism was ignored. Furthermore, the results suggest that a six-weeks huff period would be sufficient to achieve substantial EOR if this new mechanism is incorporated. On the other hand, the produced fluid in the early period was primarily composed of CO2, which would make it available for subsequent cycles. The produced gas of the well under CO2 EOR was used in an adjacent well, which resulted in similar additional oil recovery and hence, impurities in CO2 injection stream would not undermine efficiency of this EOR method. The results of this study, therefore, could potentially be used to substantially improve the evaluations of CO2 EOR in liquid-rich shale reservoirs.
Modeling of Hydrate Formation Hysteresis in Porous Media
Authors: Adams Jeremy J. , Akkutlu I. Yucel , Moridis George J.
Published: April 2019

Methane hydrate is formed in a sand pack that undergoes cooling-heating cycles over a range of temperature. Five cycles are designed so that hysteresis can be observed in the sand pack. Each cycle has a different melting temperature which leads to varying intensity of temperature relaxation effect on the hysteresis. Evidence of hysteresis is observed in three separate temperature readings of thermocouples. Formation of hydrates is dependent on the thermal cooling rate of the sand pack, and the melting temperature of the previous cycle. A temperature increase is observed in the whole system, and this increase is driven by temperature peaks indicating significant hydrate formation near the thermocouples. These peaks have important effects on the whole system. By comparing each cycle's temperature peaks, hysteresis is clearly observed at the temperature readings of the short thermocouple. The same hysteresis pattern follows for the location of the temperature peaks. When significant hydrate formation occurs in the sand pack, a steepening of the pressure decline is observed, indicating a rapid loss of free gas in the system. The pattern that is observed in the temperature peaks is also identified in the pressure profiles, thus linking the gas saturation to hydrate formation. The time derivative of pressure corroborates these findings. A new model is proposed for the prediction of secondary hydrate formation time as a function of the melting temperature the porous medium experienced.
4D Seismic and Production History Matching, a Combined Formulation Using Hausdorff and FréChet Metric
Authors: Zhang Qi , Chassagne Romain , MacBeth Colin
Published: April 2019

Integration of time-lapse seismic data into dynamic reservoir model is an efficient process in calibrating reservoir parameters update. The choice of the metric which will measure the misfit between observed data and simulated model has a considerable effect on the history matching process, and then on the optimal ensemble model acquired. History matching using 4D seismic and production data simultaneously is still a challenge due to the nature of the two different type of data (time-series and maps or volumes based).

Conventionally, the formulation used for the misfit is least square, which is widely used for production data matching. Distance measurement based objective functions designed for 4D image comparison have been explored in recent years and has been proven to be reliable. This study explores history matching process by introducing a merged objective function, between the production and the 4D seismic data. The proposed approach in this paper is to make comparable this two type of data (well and seismic) in a unique objective function, which will be optimised, avoiding by then the question of weights. An adaptive evolutionary optimisation algorithm has been used for the history matching loop. Local and global reservoir parameters are perturbed in this process, which include porosity, permeability, net-to-gross, and fault transmissibility.

This production and seismic history matching has been applied on a UKCS field, it shows that a acceptalbe production data matching is achieved while honouring saturation information obtained from 4D seismic surveys.
A Review of Numerical Modelling Techniques for Reactive Transport in Subsurface Reservoirs and Application in Mimetic Finite Difference Discretization Schemes
Authors: Abd Abdul Salam , Abushaikha Ahmad
Published: April 2019

Reactive transport is an area of growing interest to the petroleum industry due to the need to develop efficient simulators for oil production in mature and fractured fields. The subsurface flow processes are highly dependent on the chemical reaction between fluid and rocks, and between fluids themselves. This means that fluid flow in a reservoir should be characterized by mass change and chemical reactions, and thus researchers are trying to account for both phenomena through their corresponding governing equations. In this work, we discuss the early efforts to couple mass transfer and chemical reaction equations through presenting key studies in the field of modelling reactive transport and suggest a new discretization scheme for geochemical reactions. Our main objective is to improve on the formulation and simulation of reactive transport problems and explain how to implement Mimetic Finite-Difference (MFD) discretization scheme in reservoir simulators. The paper outlines the steps to discretize the governing equations of reactive transport, and construct and solve the resultant Jacobian system. The purpose of this work is to provide a clear presentation of the main mathematical and theoretical concepts of reactive transport, and how they can be applied in reservoir simulation framework. Such framework can be utilized in the future to develop a state-of-art reservoir simulator that employs Mimetic Finite Difference schemes in unstructured grids and full tensor permeability structures to solve for fluid flow in porous media, while accounting for the geochemical reactions at the subsurface.
Investigation of the Severity of Wax Deposition in Bend Pipes Under Subcooled Pipelines Conditions
Authors: Makwashi Nura , Sarkodie Kwame , Akubo Stephen , Zhao Donglin , Diaz Pedro
Published: April 2019

Curved pipes are essential components of subsea process equipment and some part of production pipeline and riser. So far, most of the studies on of wax deposition and the possible mitigation strategies have been carried out using straight pipelines, with little attention given to curved pipes. Therefore, the objective of this study is to use an experimental flow loop designed and assembled in the lab to study and understand the mechanisms and variable parameters that affect wax depositional behaviour under the single-phase flow. Series of experiments were carried out with pipes curvatures of 0, 45 and 90-degree at different flow rates (2 and 11 L/min). The sequence in which the bends are incorporated creates non-uniformity of boundary shear, flow separation, and caused isolation of fluid around the bends that affect wax deposition, which depends on flow regimes – Reynolds number along with the radius of curvature of the bend. Prior to the flow loop experiment, the waxy crude oil was characterized by measuring the viscosity, WAT (30°C), pour point (25.5°C), n-Paraffin distribution (C10 - C67), and the saturated/aromatic/resin/asphalte (SARA) fractions

Results of this study shows that the wax deposit thickness decreases at higher flow rate within the laminar (Re<2300) and turbulent (Re>2300) flow regimes. It was observed that the deposition rate was significantly higher in curved pipes, about 8 and 10% for 45 and 90-degree, respectively in comparison to the straight pipe for all flow conditions. Increase elevation of the curved pipe, however, led to a more wax deposition trend; where a higher percentage of wax deposit was observed in 45-degree compared to 90-degree curved pipe. This trend was due addition of gravity forces to the frictional forces - influenced by the physical mechanisms of wax deposition mainly molecular diffusion, shear dispersion and gravity settling. From the results of this study, a new correlation between wax deposit thickness and pressure drop was developed. A relationship was established between wax deposit thicknesses, bend angle in pipes and wax deposition mechanisms with a reasonable agreement with published data, especially for steady state condition. Therefore, this study will enhance the understanding of the wax deposition management and improve predictions for further development of a robust mitigation strategy.
Evaluation of Upscaling Approaches for the Amellago Carbonate Outcrop Model
Authors: Liu Ching-Hsien , Nunna Krishna , Syed Imroj , King Michael J.
Published: April 2019

Carbonate reservoirs are extremely challenging for reservoir modeling and flow simulation due to their high heterogeneity and the complexity of controls on the porosity and permeability. The porosity and permeability may be connected or weakly connected, which can cause difficulties in coarse grid design and upscaling of flow. We report on the application of a recently developed "Diffuse Source" upscaling approach here applied to the upscaling of a high resolution 3D carbonate reservoir model.

A high-resolution 3D geological model of the Amellago carbonate outcrop was utilized for analysis. This model, which has similar stratigraphy, structure and diagenetic controls as Middle East reservoirs, has proven to be a challenge for existing layer upgridding and flow-based upscaling approaches. We utilize flow-based "Diffuse Source" upscaling to obtain the intercell transmissibility and well indices, as this approach has improved localization and resolution compared to steady state calculations, and also allows us to distinguish between well connected and weakly connected sub-volumes.

We report on the performance of the statistical layer upgridding approaches used to design the flow simulation grid from the underlying 3D geologic model, and the impact of the choice of the heterogeneity measure (velocity error, time of flight error, or a combination of the two). We benchmarked the Diffuse Source against several methods available in the literature. Finally, we demonstrate the utility of a recently developed method for flow diagnostics that allows us to test the quality of the coarse simulation models relative to the fine-scale geologic model. All of the upscaled models are tested using commercial finite difference simulation and are compared to the upscaling approaches available within commercial flow simulation and geologic modeling applications.
Trends in the development of marketing technologies in the tourism market
Authors: Sushchenko Olena , Ekouaghe Matthnai
Published: April 2019

This article deals with trends in the development of marketing activities in the tourism market. In the field of tourist marketing should be considered in two aspects: the first aspect is a system focused on the strategy and tactics of active adaptation to the changing requirements of the tourist market; and the second aspect is the interaction of the main market elements: consumer, product, price, advertising, sales, etc. One of the types of services in tourism, which is expanding is marketing. In facts it affects the interests of every person and every organization in any given market. Marketing of tourism in the international sphere in comparison with other areas where all methods and approaches of marketing activities are actively used, remains at a lower level, of use in the promotion of tourist destination despite the fact that tourism seems to be a popular way of recreation for more than a decade. The aim of the article is to analyze the in the main tendencies in the development of the use of marketing technologies in the tourism industry services on the basis of the modern market conditions as well as the study of integrated methods of promotion of tourist destinations.
Characteristics of blood flow in the ductus venosus of fetus with congenital
development anomalies diagnosed during the first trimester
Authors: O.L. Galkina
Published: April 2019

Objectives: to analyze the characteristics of blood flow in the ductus venosus of fetus with congenital
anomalies diagnosed during the first trimester.
Materials: 20 821 first trimester pregnant women have been examined during the last 3 years. 82 fetuses
have been diagnosed with congenital anomalies. In 74 out of 82 cases assessment of blood flow took place.
A comparative analysis of the following parameters has been carried out: characteristics of blood flow in the
ductus venosus of fetus with multiple and isolated congenital anomalies, normal nuchal translucency and
expanded nuchal translucency, isolated and concomitant development anomalies of the heart and major
vessels, normal and anomalous karyotype.
Results: anomalous blood flow in the ductus venosus was recorded in 40 % of the fetuses with congenital
anomalies – the highest in the group of fetus with multiple congenital anomalies in combination with the
expanded nuchal translucency and chromosomal abnormalities – 60 %, in the group of fetus with Edwards
syndrome – 90 %.
Conclusion: the recording of abnormal blood flow in the ductus venosus of a fetus should be an indication
for an expanded anatomical assessment of the fetus and ultrasound monitoring, as sensitive markers of fetal
anomalies and chromosomal abnormalities.
Arthrogryposis and evaluation of motor activity of the fetus
Authors: N.V. Mashinets, V.N. Demidov
Published: April 2019

The literature review and own observation of prenatal diagnosis of arthrogryposis of the fetus are presented. The peculiarity of this report is that during the cardiotocographic study it was found that the fetus
with arthrogryposis has slow movements, manifested by the movement of the body and head, and the lack of
rapid movements that the woman feels.
A rare case of acute twin-to-twin transfusion syndrome with late
manifestation in monochorionic diamniotic twins
Authors: E.R. Semenova, I.G. Filippova, I.A. Prosvirnin
Published: April 2019

A rare case of acute twin-to-twin transfusion syndrome developed after 32 weeks of gestation is presented.
This syndrome caused intrauterine death of one of the twins and newborn’s death of another one. Previous
examination was performed 19 days earlier. Ultrasound examination, Doppler and fetal monitoring have
shown normal findings. Postnatal colour stain of the placental anastomosis, pathophysiological research of
lost life fetus and clinical tests of survived newborn confirmed our suggestions.
Bir Öğrenciye Temel Bölme İşlemlerinde Akıcılık Kazandırmada Dinleyerek İşlem Yapma Uygulamalarının Etkililiği
Authors: ALPTEKİN Serpil
Published: April 2019

Araştırmanın
amacı, dinleyerek işlem yapma (DİY) ile yapılan öğretim uygulamalarının
matematik performansı düşük bir öğrencinin temel bölme işlemlerinde akıcılık
düzeyini artırmada etkililiğini, öğrencinin ulaşmış olduğu akıcılık
performansını başka kişi ve eğitim ortamlarına genelleyip genellemediğini ve
aradan belli bir süre geçtikten sonra da sürdürüp sürdürmediğini belirlemektir.
Araştırmada beceriler arası çoklu yoklama modeli kullanılmıştır.
Katılımcı, 12 yaşında, yedinci sınıf düzeyinde, genel eğitim sınıfına devam
eden, tanı almamış ancak matematik performansı düşük bir kız öğrencidir.
Araştırmanın bulguları, DİY uygulamalarının matematik performansı düşük bir
öğrencinin temel bölme işlemlerindeki akıcılık düzeyini artırmada etkili olduğunu,
ulaşmış olduğu akıcılık düzeyini başka öğretmen ve eğitim ortamına
genellediğini ve performansını 7, 14 ve 21. günlerde de sürdürdüğünü
göstermiştir. Sosyal geçerlik bulguları incelendiğinde, öğretmen ve öğrencinin uygulamaya ilişkin olumlu görüşleri, DİY
uygulamalarının kabul edilebilirliğini ve araştırma sonuçlarının yüksek düzeyde
anlamlı olduğunu göstermiştir. Ayrıca sosyal karşılaştırma ortalamaları dikkate
alındığında öğrenci akranlarının akıcılık ortalamasına çok yaklaşmıştır.
Bu bulgular alanyazın araştırmaları ile tartışılmıştır.
Simultaneous removal of Cd2+ and Zn2+ from aqueous solution using an upflow Al-electrocoagulation reactor: optimization by response surface methodology
Authors: Burboa-Charis Vianey Ariadna , Moreno-Román Eddy Jonatan , Contreras Juan Antonio Vidales , García-Gómez Celestino
Published: April 2019

The presence of heavy metals in the environment has increased, and cadmium (Cd) and zinc (Zn) are considered to be among the most dangerous. An upflow Al-electrocoagulation reactor was used to remove Cd2+ and Zn2+ ions from aqueous media. The system consisted of perforated aluminum circular electrodes for fluid distribution with elimination of external agitation. The effect of different parameters, i.e. current intensity, electrolysis time, concentration of Cd2+ and Zn2+ ions and electrolytic support dose were optimized by response surface methodology. The results indicated that increasing the current intensity and the electrolysis time had a positive effect on the elimination efficiency of the pollutant ions. Likewise, increasing the dose of electrolytic support and decreasing the concentration of the pollutants improved the efficiency of the system. The optimal results were: current intensity of 0.4 A, electrolysis time of 40 min, ion concentration of 44.6 mg·L−1 and electrolytic support dose of 0.56 mg·L−1, with the maximum elimination percentages of 96 ± 3.8% and 96 ± 2.7% for Cd2+ and Zn2+, respectively. This study showed that the electrocoagulation process in an upflow electrocoagulation reactor could be successfully applied to remove pollutants from water.
Propagation of acoustic waves in layered porous media
Authors: Dmitriev V.L. , Ponomareva Е.А.
Published: April 2019

The paper considers the processes of reflection and transmission acoustic waves at the interface between two porous media, saturated liquid or gas. The cases of a porous medium whose layers have the same porosity, but are saturated with different fluids. Based The dispersion relation and the conditions at the interface between the media are obtained reflection and transmission coefficients. The possibility determination of the parameters of the porous material and its saturating fluid based on the signal reflected from the interface.
The effect of static pressure on the formation of carbon dioxide hydrate behind the shock wave in the gas-liquid medium
Authors: Dontsov V.E. , Chernov A.A. , Dontsov E.V.
Published: April 2019

The processes of crushing, dissolving and hydrate formation behind a shock wave of moderate amplitude in water with bubbles of carbon dioxide at various initial static pressures. Calculations are presented for the model of gas hydration behind a shock wave.
Modelling of local admixture stratification in in disperse flows with kinematic singularities
Authors: Lebedeva N.A.
Published: April 2019

Development of mesoscale non-uniformities of the dispersed phase in dusty-gas flows with kinematic singularities is considered. As examples, the following flows with dispersed admixture are studied: a flow near a stagnation point of two colliding viscous streams, gas-dispersed flow near a rigid wall, flows with localized vorticity, an unsteady flow in a neighborhood of a zero acceleration point.
Application of the special series method for representing solutions of the equation of nonstationary gas flows
Authors: Filimonov M.Yu.
Published: April 2019

For the Lin-Reissner-Tsien equation describing nonstationary transonic gas flows, solutions are constructed in the form of special power series in specially chosen functions. Such a choice of functions makes it possible to find the coefficients of the series by sequential solving both ordinary linear differential equations and linear partial differential equations. The convergence of the constructed series is investigated.
Recent Advance in Polymer Based Microspheric Systems for Controlled Protein and Peptide Delivery
Authors: Yang Yuanyuan , Chen Qiling , Lin Jianyu , Cai Zheng , Liao Guochao , Wang Kai , Bai Lei , Zhao Peng , Yu Zhiqiang
Published: April 2019

Sustained-release systems made by biodegradable polymers for protein and peptide
drug delivery have received considerable attention by academic researchers and major pharmaceutical
companies around the world. Various types of biodegradable materials, including
natural and synthetic polymers, have been applied to form protein and peptide drug carriers.
Among these material candidates, poly lactic acid (PLA) and poly lactic-co-glycolic acid
(PLGA) are the most commonly used biodegradable materials in the development of protein
and peptide microspheres. In addition, many microsphere preparation technologies, including
spray drying, coacervation, multiple emulsion solvent evaporation method and microporous
membrane emulsification have been developed for microspheres preparation. In this review,
we particularly summarize and briefly introduce the materials and methods that are used to
fabricate microspheres as protein delivery systems. The existing opportunities and challenges
for successful protein delivery are also discussed.
Limitations and Opportunities in Topical Drug Delivery: Interaction Between Silica Nanoparticles and Skin Barrier
Authors: Arriagada Francisco , Morales Javier
Published: April 2019

The first limiting barrier for the transport in the skin is the stratum corneum; different strategies have
been developed to overcome this barrier, including chemical enhancers. However, these penetration enhancers
have limitations, including toxic adverse effects. In this context, research into nanomaterials has provided new
tools to increase the residence time of drugs by generating a reservoir, increasing the specificity of drugs and
reducing their adverse effects, and improving the penetration of drugs that are difficult to formulate. Silica
nanoparticles have been proposed as suitable nanocarriers for skin delivery. Unfortunately, the mechanisms involved
in the interaction, transport and fate of silica nanoparticles in the skin have not been fully investigated.
This paper reviews significant findings about the interaction between silica-based nanocarriers and the skin. First,
this review focuses on the properties and functions of the skin, the skin penetration properties of silica nanoparticles,
their synthesis strategies and their toxicity. Finally, advances and evidence on the application of silica nanocarriers
in skin drug delivery are provided, in which the use of nanoparticles increases the stability and solubility
of the bioactive compound, enhancing its performance, act as penetrator enhancer and improving controlled release.
Thus, improving the treatment of some skin disorders.
The Regulatory Roles of Long Non-Coding RNA in the Chemoresistance Process of Ovarian cancer
Authors: Qu Jiayuan , Kamal Mohammad Amjad , Yuan Chengfu
Published: April 2019

Background:

Ovarian cancer is the most malignant tumor in gynecological tumors, with low five-year
survival rate. The main reasons are diagnosis at advanced stages (the early symptoms are uncharacteristic, and
most are diagnosedlate.), relapse, and resistance to existing chemotherapy drugs.

Methods:

Search strategy was performed in the following steps. Firstly, LncRNA related to ovarian cancer was
retrieved by using the LncRNA Disease database, and articles were searched by searching keywords: ovarian
cancer, drug resistance, and LncRNA retrieved from the LncRNA Disease database.

Results/Conclusion:

With the development of the study on drug resistance of ovarian cancer, the role of
LncRNAs as sensitive biomarker and therapeutic target has emerged, providing a direction for precision medicine
of ovarian cancer resistance.
Statistical Modelling Outcome of In Vitro Fertilization and Intracytoplasmic Sperm Injection: A Single Centre Study
Authors: Xu Boyun , Liu Chang , Qian Lianfen , Qu Yue , Su Weijue , Xu Jialing , Zhao Junzhao
Published: April 2019

Background:

Assisted reproductive techniques (ART) have been extensively used to
treat infertility. Inaccurate prediction of a couple’s fertility often leads to lowered self-esteem for
patients seeking ART treatment and causes fertility distress.

Objective:

This prospective study aimed to statistically analyze patient data from a single
reproductive medical center over a period of 18 months, and to establish mathematical models that
might facilitate accurate prediction of successful pregnancy when ART are used.

Methods:

In the present study, we analyzed clinical data prospectively collected from 760 infertile
patients visiting the second Affiliated Hospital and Yuying Children’s Hospital of Wenzhou
Medical University between June 1, 2016 and December 31, 2017. Various advanced statistical
methods, including broken-line regression, were employed to analyze the data.

Results:

Age remained the most important factor affecting the outcome of IVF/ICSI. Using the
broken-line regression model, the fastest clinical pregnancy declining age was between 25 and 32.
Female infertility type was found to be a key predictor for the number of good-quality embryos and
successful pregnancy, along with the antral follicle count (AFC), total number of embryos,
recombinant follicle stimulating hormones (rFSH) dosage, estradiol (E2) on the trigger day, and
total number of oocytes retrieved. rFSH dosage was also significantly associated with the number
of oocytes retrieved and the number of frozen embryos.

Conclusion:

The fastest clinical pregnancy declining age is ranged between 25 and 32, and female
infertility type is evidenced as another key predictive factor for the cumulative outcome of ART.
Decreased Disposition of Anticancer Drugs Predominantly Eliminated via the Liver in Patients with Renal Failure
Authors: Fujita Ken-ichi , Matsumoto Natsumi , Ishida Hiroo , Kubota Yutaro , Iwai Shinichi , Shibanuma Motoko , Kato Yukio
Published: April 2019

Background:

Evidence has revealed that renal impairment can affect the systemic exposure of drugs which are predominantly eliminated via the liver. The modulation of drug-metabolizing enzymes and transporters expressed in the liver and/or small intestine by diverse entities, including uremic toxins, in systemic circulation of patients with severe renal failure is considered as the cause of atypical pharmacokinetics, which sometimes induce undesirable adverse events that are especially critical for drugs with narrow therapeutic window such as anticancer drugs. A dosing strategy for anticancer drugs in these patients needs to be established.

Methods:

The effects of renal impairment on the systemic exposure and safety of anticancer drugs were summarized. The proposed mechanisms for the alterations in the pharmacokinetics of these anticancer drugs were also discussed.

Results:

Changes in pharmacokinetics and clinical response were reported in 9 out of 10 cytotoxic anticancer drugs investigated, although available information was limited and sometimes controversial. Systemic exposure of 3 out of 16 tyrosine kinase inhibitors was higher in patients with severe renal failure than that in patients with normal kidney function. An increase in systemic exposure of anticancer drugs in patients with renal impairment is likely to be observed for substrates of OATP1B1, despite the limited evidence.

Conclusion:

The molecular basis for the effect of uremia on non-renal drug elimination still needed to be clarified with further studies to generate generalizable concepts, which may provide insights into establishing better clinical usage of anticancer drugs, i.e. identifying patients at risk and dose adjustment.
Tanshinone IIA Promotes Macrophage Cholesterol Efflux and Attenuates Atherosclerosis of apoE-/- Mice by Omentin-1/ABCA1 Pathway
Authors: Tan Yu-lin , Ou Han-xiao , Zhang Min , Gong Duo , Zhao Zhen-wang , Chen Ling-yan , Xia Xiao-dan , Mo Zhong-cheng , Tang Chao-ke
Published: April 2019

Background:

Tanshinone IIA (Tan IIA) and Omentin-1 have a protective role in the cardiovascular system. However, if and how Tan IIA and Omentin-1 regulate cholesterol metabolism in macrophages has not been fully elucidated.

Objective:

To investigate the possible mechanisms of Tan IIA and Omentin-1 on preventing macrophage cholesterol accumulation and atherosclerosis development.

Methods:

The effect of Tan IIA on the protein and mRNA levels of Omentin-1 and ATP-binding cassette transporter A1 (ABCA1) in macrophages was examined by Western blot and qRT-PCR assay, respectively. Cholesterol efflux was assessed by liquid scintillation counting (LSC). Cellular lipid droplet was measured by Oil Red O staining, and intracellular lipid content was detected by high performance liquid chromatography (HPLC). In addition, the serum lipid profile of apoE−/− mice was measured by enzymatic method. The size of atherosclerotic lesion areas and content of lipids and collagen in the aortic of apoE−/− mice were examined by Sudan IV, Oil-red O, and Masson staining, respectively.

Results:

Tan IIA up-regulated expression of Omentin-1 and ABCA1 in THP-1 macrophages, promoting ABCA1-mediated cholesterol efflux and consequently decreasing cellular lipid content. Consistently, Tan IIA increased reverse cholesterol transport in apoE−/− mice. Plasma levels of high-density lipoprotein cholesterol (HDL-C), ABCA1 expression and atherosclerotic plaque collagen content were increased while plasma levels of low-density lipoprotein cholesterol (LDL-C) and atherosclerotic plaque sizes were reduced in Tan IIA-treated apoE−/− mice. These beneficial effects were, however, essentially blocked by knockdown of Omentin-1.

Conclusion:

Our results revealed that Tan IIA promotes cholesterol efflux and ameliorates lipid accumulation in macrophages most likely via the Omentin-1/ABCA1 pathway, reducing the development of aortic atherosclerosis.
New Rules on Patient’s Safety and Professional Liability for the Italian Health Service
Authors: Albolino Sara , Bellandi Tommaso , Cappelletti Simone , Di Paolo Marco , Fineschi Vittorio , Frati Paola , Offidani Caterina , Tanzini Michela , Tartaglia Riccardo , Turillazzi Emanuela
Published: April 2019

Background:

The phenomenon of clinical negligence claims has rapidly spread to United States, Canada and Europe assuming the dimensions and the severity of a pandemia. Consequently, the issues related to medical malpractice need to be studied from a transnational perspective since they raise similar problems in different legal systems.

Methods:

Over the last two decades, medical liability has become a prominent issue in healthcare policy and a major concern for healthcare economics in Italy. The failures of the liability system and the high cost of healthcare have led to considerable legislative activity concerning medical malpractice liability, and a law was enacted in 2012 (Law no. 189/2012), known as the “Balduzzi Law”.

Results:

The law tackles the mounting concern over litigation related to medical malpractice and calls for Italian physicians to follow guidelines. Briefly, the law provided for the decriminalisation of simple negligence of a physician on condition that he/she followed the guidelines and “good medical practice” while carrying out his/her duties, whilst the obligation for compensation, as defined by the Italian Civil Code, remained. Judges had to consider that the physician followed the provisions of the guidelines but nevertheless caused injury to the patient.

Conclusion:

However, since the emission of the law, thorny questions remain which have attracted renewed interest and criticism both in the Italian courts and legal literature. Since then, several bills have been presented on the topic and these have been merged into a single text entitled “Regulations for healthcare and patient safety and for the professional responsibility of healthcare providers”.
Advanced Loss Eventuality Assessment and Technical Estimates: An Integrated Approach for Management of Healthcare-Associated Infections
Authors: Gatto Vittorio , Scopetti Matteo , La Russa Raffaele , Santurro Alessandro , Cipolloni Luigi , Viola Rocco V. , Di Sanzo Mariantonia , Frati Paola , Fineschi Vittorio
Published: April 2019

Background:

Healthcare Associated Infections (HAIs) represent a crucial issue in health and
patient safety management due to the persistent nature, economic impact and possible preventability of
the phenomenon. Compensation claims for damages resulting from HAI could provide insights that can
improve the understanding of suboptimal steps in the therapeutic process, enable an estimate of costs related
to infectious complications, and guide the development of planning tools for implementation of the
quality of care.

Objective:

This paper analyzes all the HAI claims received at the Umberto I General Hospital of Rome
across a five-year period with the aim of outlining a methodological approach to the litigation management
and of characterizing the economic impact of infections on health facilities resources.

Methods:

All claims received during the study period have been classified according to the International
Classification for Patient Safety (ICPS) system. Subsequently, claims related to Healthcare Associated
Infections were evaluated through an innovative tool for determination of the risk of loss, the Advanced
Loss Eventuality Assessment (ALEA) score.

Results:

The results obtained demonstrate the relevance of a correct management of HAI claims in the administration
of a health care system. Specifically, the cases examined during the study highlighted the significant
impact of infectious diseases of a nosocomial nature in terms of frequency and economic exposure.

Conclusion:

The proposed methodological approach allows a productive analysis of the internal processes,
providing fundamental data for the refinement of the preventive strategies and for the rationalization
of the resources through the expenditure forecasts.

Article Highlights Box:

Healthcare-Associated Infections represent an essential element to consider in
the management of health facilities.
• Many studies highlight the economic burden of Healthcare-Associated Infections in health policies.
• Litigation management represents a useful resource in the prevention of Healthcare Associated Infections.
• Appropriate clinical risk management policies in the field of Healthcare-Associated Infections allow
the implementation of preventive measures, the reduction of the incidence of the phenomenon and the
quality of care.
• The costs of Healthcare-Associated Infections can be limited through a systematic methodological approach
based on Advanced Loss Eventuality Assessment and technical estimate of the value of each case.
• The application of a standardized system would be desirable in any health facility despite the potential
methodological, technical, behavioral and financial issues.
Evaluation of Changes in the Expression Pattern of EDIL3 in Different Grades of Endometrial Cancer
Authors: Oplawski Marcin , Dziobek Konrad , Zmarzły Nikola , Grabarek Beniamin , Tomala Barbara , Leśniak Ewa , Adwent Iwona , Januszyk Piotr , Dąbruś Dariusz , Boroń Dariusz
Published: April 2019

Background:

EDIL3 is an extracellular matrix protein that plays a key role in angiogenesis. Changes in the pattern of its expression also affect cellular processes and the tumor microenvironment. Elevated level of EDIL3 is considered an unfavorable prognostic marker of survival.

Objective:

The aim of this study was to evaluate the changes in EDIL3 expression in endometrial cancer at various degrees of its differentiation (G1-G3) and to discuss its potential role as a molecular diagnostic marker and therapeutic target.

Methods:

The study group consisted of 45 patients with endometrial cancer: G1, 17; G2, 15; G3, 13. The control group (C) included 15 patients without neoplastic changes. The expression of EDIL3 was assessed using immunohistochemistry. Statistical analysis was performed using the Statistica 12 PL software (p<0.05).

Results:

Analysis of EDIL3 expression showed that the average optical density of the reaction product in G1 reached 130% of the control, while the values in G2 and G3 were 153% and 158%, respectively. Regardless of the endometrial cancer grade, an increase in EDIL3 level was observed compared to the control.

Conclusion:

In our study, we demonstrated overexpression of EDIL3 protein in endometrial cancer. Differences in expression between degrees of tumor differentiation suggest the potential of using changes in EDIL3 level as a new complementary diagnostic marker and target for anti-angiogenic therapy.