An efficient 3D cell-based discrete fracture-matrix flow model for digitally captured fracture networks

Complex hydraulic fracture networks are critical for enhancing permeability in unconventional reservoirs and mining indus-tries.However,accurately simulating the fluid flow in realistic fracture networks(compared to the statistical fracture net-works)is still challenging due to the fracture complexity and computational burden.This work proposes a simple yet efficient numerical framework for the flow simulation in fractured porous media obtained by 3D high-resolution images,aiming at both computational accuracy and efficiency.The fractured rock with complex fracture geometries is numerically constructed with a cell-based discrete fracture-matrix model(DFM)having implicit fracture apertures.The flow in the complex fractured porous media(including matrix flow,fracture flow,as well as exchange flow)is simulated with a pipe-based cell-centered finite volume method.The performance of this model is validated against analytical/numerical solutions.Then a lab-scale true triaxial hydraulically fractured shale sample is reconstructed,and the fluid flow in this realistic fracture network is simu-lated.Results suggest that the proposed method achieves a good balance between computational efficiency and accuracy.The complex fracture networks control the fluid flow process,and the opened natural fractures behave as primary fuid pathways.Heterogeneous and anisotropic features of fluid flow are well captured with the present model.

Cell-based therapies for limbal stem cell deficiency: a literature review

Background and Objective:Limbal stem cell deficiency(LSCD)is characterized by the insufficiency of limbal stem cells to maintain the corneal epithelium.Severe cases of LSCD may be treated with limbal transplantation from healthy autologous or allogeneic limbal tissue.Multiple cell-based therapies have been studied as alternative treatments to improve success rates and minimize immunosuppressive regimens after allogeneic transplants.In this review,we describe the success rates,and complications of different cell-based therapies for LSCD.We also discuss each therapy’s relative strengths and weaknesses,their history in animal and human studies,and their effectiveness compared to traditional transplants.Methods:PubMed was searched for publications using the terms LSCD,cell-based therapy,cultivated limbal epithelial transplantation(CLET),cultivated oral mucosal epithelial transplantation(COMET),and mesenchymal stem cells from 1989 to August 2022.Inclusion criteria were English language articles.Exclusion criteria were non-English language articles.Key Content and Findings:current cell-based therapies for LSCD are CLET and non-limbal epithelial cells.Non-limbal epithelial cell methods include COMET,conjunctival epithelial autografts,and mesenchymal stem/stromal cells(MSCs).Moreover,several alternative potential sources of non-limbal cells have described,including induced pluripotent stem cells(iPSCs),human embryonic stem cells(hESCs),human dental pulp stem cells,hair follicle bulge-derived epithelial stem cells,amniotic membrane epithelial cells,and human umbilical cord lining epithelial cells.Conclusions:Cell-based therapies are a promising treatment modality for LSCD.While CLET is currently the only approved cell-based therapy and is only approved in the European Union,more novel methods have also been shown to be effective in human or animal studies thus far.Non-limbal epithelial cells such as COMET are also an alternative treatment to allogeneic transplants especially as a surface stabilizing procedure.iPSCs are currently being studied in early phase trials and have the potential to revolutionize the way LSCD is treated.Lastly,cell-based therapies for restoring the limbal niche such as mesenchymal stem cells have also shown promising results in the first human proof-of-concept study.Several potential sources of non-limbal cells are under investigation.

基于随机场正交展开理论的Cell-based随机光滑有限元方法

为解决工程结构中随机参数大变异问题,提出基于正交展开理论的Cell-based随机光滑有限元方法.该方法采用Karhunen-Loève级数将随机场分解为不相关随机变量,再使用混沌多项式将位移随机响应展开,将展开后的随机场及位移响应引入到Cell-based光滑有限元中.详细推导了基于正交展开理论的Cell-based随机光滑有限元平衡方程,进一步给出了结构位移均值与协方差矩阵的计算公式,具有对网格要求低、计算精度高的优点,并对材料特性具有随机性的带孔方板的随机响应问题进行了分析,数值算例结果表明该方法是正确有效的.

含裂纹压电材料的Cell-Based光滑有限元法

裂纹缺陷限制了压电材料更广泛的应用和相关器件性能的进一步提升.为提高求解压电材料断裂参数的精度和效率,将复势函数法和Cell-based光滑有限元法引入到含裂纹平面压电材料问题中,提出了含裂纹压电材料的Cell-based光滑有限元法.以含中心裂纹压电平板的问题为例,对不同材料、裂纹长度、网格和光滑子元数下的正则强度因子进行了讨论,并与FEM作了对比,数值算例结果表明,Cell-based光滑有限元法改善了有限元法刚度"偏硬"的缺点,具有高精度、高效率的优点.

复合材料层合板的摄动随机Cell-Based光滑有限元

随机性是实际工程结构的固有特性,如何更真实地描述含随机参数结构的随机响应及统计特性,对工程结构的可靠性设计具有非常重要的意义。本文基于Cell-Based光滑有限元,采用四边形单元,推导了基于一阶剪切变形理论的复合材料层合板的光滑有限元公式,降低了网格划分要求,适应不规则网格,并采用离散剪切间隙有效地消除了剪切自锁;结合摄动法和随机场理论,导出了复合材料层合板的摄动随机光滑有限元平衡方程,并给出了结构随机响应数字特征的计算公式,求解了材料属性含随机性的复合材料层合板的随机响应问题,数值算例结果表明了本方法的有效性和准确性。

Fortuitous benefits of activity-based rehabilitation in stem cell-based therapy for spinal cord repair: enhancing graft survival

Traumatic injuries to spinal cord elicit diverse signaling pathways leading to unselective and complex pathological outcomes：death of multiple classes of neural cells,formation of cystic cavities and glial scars,disruption of axonal connections,and demyelination of spared axons,all of which can contribute more or less to debilitating functional impairments found in patients with spinal cord injury.

Drug-and cell-based therapies for targeting neuroinflammation in traumatic brain injury

TBI pathology： Traumatic brain injury （TBI） is caused by an external force to the head, resulting in trauma to the brain. Approximately 1.7 million Americans suffer from TBI every year. Out of the 1.7 million suffering from TBI, an estimated 52,000 injuries result in death, leaving a mass amount of peo- ple with symptoms that could last a few days, a few years, or their entire life （Faul et al., 2010）. TBI can be classified as mild, moderate and severe. Depending on the classification and the extent of the injury, TBI can cause both physical symptoms and cognitive disorders （Lozano et al., 2015）.

Seropositivity rates of water channel protein 4 antibodies compared between a cell-based immunofluorescence assay and an enzyme-linked immunosorbent assay in neuromyelitis optica patients

A total of 66 samples （from 27 cases with neuromyelitis optica, 26 cases with multiple sclerosis, aa 13 cases with optic neuritis） were tested for aquaporin-4 antibody by a cell-based immunofluorescence assay and an enzyme-linked immunosorbent assay. The sensitivities and specificities of the two assays were similar. We further analyzed an additional 68 patients and 93 healthy controls using the enzyme-linked immunosorbent assay. A Kappa test showed good consistency between the two methods in terms of detection of anti-aquaporin-4 antibody in the se of neuromyelitis optica patients. No significant correlations were identified with onset age or disea duration, suggesting that aquaporin-4 antibody is a good marker for neuromyelitis optica. The enzyme-linked immunosorbent assay can be used for quantifying aquaporin-4 antibody concentrations and may be useful to dynamically monitor changes in the levels of aquaporin-4 antibody during disease duration.

Potential of transposon-mediated cellular reprogramming towards cell-based therapies

Induced pluripotent stem(iPS)cells present a seminal discovery in cell biology and promise to support innovative treatments of so far incurable diseases.To translate iPS technology into clinical trials,the safety and stability of these reprogrammed cells needs to be shown.In recent years,different non-viral transposon systems have been developed for the induction of cellular pluripotency,and for the directed differentiation into desired cell types.In this review,we summarize the current state of the art of different transposon systems in iPS-based cell therapies.

The potential of stem cell-based therapy for retinal repair

Like injured neurons in the brain or spinal cord, neurons in the retina are incapable to regenerate following injury and ultimately would lead to irreversible neuronal loss and vision impairment. Over decades, extensive effort has been made to develop strategies to protect retinal neurons from death; however, the outcome is limited （Pettmann and Henderson, 1998; Bahr, 2000; Lagali and Picketts, 2011）. Replacing the degenerated retinal neurons by newly generated and functional neurons would be an ideal scenario. The rapid development of stem cell biology has recently demonstrated that stem cells could be a potential source of cells for cell replace- ment therapy because these cells have the self-renewal capacity and could be differentiated into many cell types. This review will dis- cuss the therapeutic potential of stem cell-based therapy to retinal degenerative diseases.

Cell-Based Biosensors and Bio-MEMS for Its New Applications

This paper reviews a novel cell-based biosensor and Bio-MEMS which incorporate living cells as sensing elements that convert a change in immediate environment to signals conducive for processing.It is characterized with high sensitivity,excellent selectivity and fast response and have been implemented for a number of applications ranging from pharmaceutical screening to environmental pollutant detection.This paper also introduces our recent work about Light-Addressable Potentiometric Sensors (LAPS),Field Effect Transistor (FET),Micro-Electrode Array Sensors (MEAS) and Bio-MEMS for detecting the changes of concentration of extracellular ions and the action potential of living cell under effect of drugs and environmental parameters.Finely, the paper gives some prospects of cell-based biosensors in the future.

Development of PDMS-based Microfluidic Device for Cell-based Assays

In a single step photolithography, muhi-level microfluidic device is fabricated by printing novel architectures on a film photomasks. The whole fabrication process is executed by classical PCB technology without the need to access clean room facilities. Different levels of protruding features on PCB master are produced by exposing a photomask with specifically arranged "windows and rims" architectures, followed by chemical wet etching. Poly(dimethylsiloxane)(PDMS) is then molded against the positive relief master to generate microfluidic device featured with multi-level sandbag structure and peripheral microchannels. This sandbag structure is an analog to traditional dam or weir for particle entrapment. The microstructure does not collapse when subjected to applied pressure, which is suitable for operation on elastic PDMS substrate.Typical immunocytochemcial staining assays were performed in the microdevice to demonstrate the applicability of the sandbag structure for cellular analysis. This simplified microfabrication process employs low-cost materials and minimal specialized equipment and can reproducibly produce mask lines with about 20 μm in width, which is sufficient for most microfluidic applications.

Unraveling pathological mechanisms in neurological disorders:the impact of cell-based and organoid models

Cell-based models are a promising tool in deciphering the molecular mechanisms underlying the pathogenesis of neurological disorders as well as aiding in the discovery and development of future drug therapies.The greatest challenge is creating cell-based models that encapsulate the vast phenotypic presentations as well as the underlying genotypic etiology of these conditions.In this article,we discuss the recent advancements in cell-based models for understanding the pathophysiology of neurological disorders.We reviewed studies discussing the progression of cell-based models to the advancement of three-dimensional models and organoids that provide a more accurate model of the pathophysiology of neurological disorders in vivo.The better we understand how to create more precise models of the neurological system,the sooner we will be able to create patient-specific models and large libraries of these neurological disorders.While three-dimensional models can be used to discover the linking factors to connect the varying phenotypes,such models will also help to understand the early pathophysiology of these neurological disorders and how they are affected by their environment.The three-dimensional cell models will allow us to create more specific treatments and uncover potentially preventative measures in neurological disorders such as autism spectrum disorder,Parkinson’s disease,Alzheimer’s disease,and amyotrophic lateral sclerosis.

DESIGN OF MICROPHYSIOMETER BASED ON MULTIPARAMETER CELL-BASED BIOSENSORS FOR QUICK DRUG ANALYSIS

Cellular metabolism arouses the changes of substance in extracellular physiological microenvironment,and the metabolic level reflects the physiological state of cells.This paper developed a novel microphysiometer automatic analysis instrument based on multiparameter cell-based biosensors for quick drug analysis.This study included the multiparameter cell-based biosensors,cell culture chamber,drug auto-injection detection and analysis.The analysis instrument was capable of real-time detection for the acidic product and other chemical parameters generated by the cellular metabolism in the micro-volume.Finally,the paper employs human breast cancer cell line MCF-7 and drug experiments to verify the performance of microphysiometer,and study effects of different drugs on cell metabolism.Further,the research explores drug analysis method of the multiparameter microphysiometer.The results showed that the cell-based microphysiometer system provides a utility platform for rapid,long-term and automatic cell physiological environment detection and drug analysis.

Development of a Cell-based Model to Derive Direct Runoff Hydrographs for Ungauged Mountainous Basins

A model to derive direct runoff hydrograph for an ungauged basin using the physical properties of the basin is presented. The basin is divided into grid cells and canal elements. Overland flow is generated from each grid cell of the basin by application of continuous effective rainfall of I mm/hr to the basin, The flow generated is routed through downstream grid cells and the canal elements using the kinematic wave approach. The travel time for direct runoff from each grid cell to the basin outlet is calculated and the S-curve is derived for the basin. The S-curve is used to derive the unit hydrograph of a given duration for the basin. The model, referred as Cell-basin model was applied to the Upper Kotmale Basin in Sri Lanka and the model predictions of direct runoff hydrographs for rainfall events agreed with the observations to a reasonable accuracy. Comparison of the unit hydrographs obtained from the model and from the conventional Snyder＇s synthetic unit hydrograph using regionalized parameters assuming the basin as an ungauged basin, with the unit hydrograph derived from the observations showed that the model predicted unit hydrograph was more suitable than that obtained by Snyder＇s method for Sri Lankan up country basins. Thus, the present model is a useful tool to obtain direct runoff hydrograph for ungauged basins.

力电湿多物理场耦合Cell-Based光滑有限元法研究

为了解决压电结构在实际工程应用中受到空气湿度影响的问题,基于压电材料的本构方程、几何方程和平衡方程提出了力电湿多物理场耦合Cell-based光滑有限元模型.建立了一种新型压电俘能器,并对其简化模型的静力学性能进行求解,对比了不同湿度变化对结构性能的影响.与有限元法的计算结果对比,Cell-based光滑有限元法采用较少的网格就能够达到与有限元法采用较多的网格相同的精度,验证了本方法的正确性和有效性.研究发现,较小的湿度变化给结构的广义位移带来了较大的影响.压电结构在潮湿环境下的性能研究为复合材料产品化过程提供了理论依据.

A Novel Structure of LAPS Array for Cell-Based Biosensor

The light-addressable potentiometric sensor (LAPS) is a semiconductor-based cellular biosensor with an electrolyte-insulator-semiconductor (EIS) structure.By depositing biocompatible layers on the sensing surface for cell culture, it can be used to detect bioelectrical parameters of cells.The characteristic curve for photocurrent versus applied bias voltage to the system shows a current-voltage curve (Ⅰ-Ⅴcurve).This technique can be used to detect the action potential changes towards different drugs based on the bias voltage dependence of an optical current,and provides a dynamic system by scanning light beam at the very cell on the sensor device.The LAPS overcomes the limitation of recording sites,but high spatial resolution and sensitivity are also paramount.This paper discussed a novel structure of LAPS array for extracellular monitoring to decrease potential noise level.Both characteristics of active recording array areas and cell culture conditions are measured.

Cell-based therapy in Alzheimer's disease: can human fetal cholinergic neurons “untangle the skein”?

Alzheimer＇s disease（AD）is a devastating neurodegenerative disorder and the most common form of old-age dementia.The disease is characterized by a progressive decline in cognitive functions,gradual loss of memory and ability to perform everyday activities,and leads to inevitable death within 3 to 9 years atter diagnosis.

Tubular conduits,cell-based therapy and exercise to improve peripheral nerve regeneration

Peripheral nerve injuries （PNI） are a major clinical prob- lem. In general, PNI results from motor vehicle accidents, lacerations with sharp objects, penetrating trauma （gunshot wounds） and stretching or crushing trauma and fractures. It is estimated that PNI occur in 2.8% of trauma patients and this number reaches 5% if plexus and root lesions are in- cluded. However, due to lack of recent epidemiological stud- ies, these data probably underestimate the actual number of nerve injuries

Identification of HCV Inhibitors from a Cell-Based Sub-Genomic Replicon Screen

A high throughput screen of the Pfizer compound collection was carried out using a hepatitis C virus (HCV) genotype 1b subgenomic replicon cell line. Those confirmed hits that demonstrated broad spectrum activity without overt cytotoxicity were further evaluated, leading to the identification of a series of pyrrolopyridines with excellent antiviral activity in a fully infectious HCV cell-based assay and pharmacokinetic properties.