Spontaneous Potentials Research Articles

Geophysical research of underground hydraulic structures, old Glubochinsky water tunnel case study

Research objective is to study the features of geophysical fields and parameters in the area of the artificial underground water tunnel and estimate the capabilities of geophysical methods of identifying hidden underground industrial facilities. Methods of research. Measurements of self-potential signals (SP) were carried out using nonpolarizing electrodes and an electrical exploration receiver. The magnetic exploration was carried out by a proton magnetometer. Electrotomography was carried out using multielectrode electrical survey equipment with a Schlumberger symmetrical scheme of surveys. The microseismic background was recorded using an autonomous seismic station. The georadar survey was carried out using the SIR-3000 ground penetrating radar and antennas with the frequencies of 100 MHz and 270 MHz. Results. Based on the survey results, graphs of magnetic and self-potential fields, electrotomographic and microseismic sections, and radarogram were built on the research profile. The research has shown different levels of the magnetic field and the SP in the area of volcanic rocks and dikes of gabbro-dolerites occurrence. A significant increase in microseismic noise was observed with an increase in the weathering crust thickness. A local decrease in the SP potential, abnormally high values of specific electrical resistivity and intensive reflections of radio waves from the tunnel top were recorded above the underground water tunnel. Conclusions. Qualitative and quantitative geophysical characteristics were obtained in the area of the old underground water tunnel. The research showed different levels of the magnetic field and spontaneous polarization potentials in the occurrence area of rocks of different composition. A significant increase in microseismic noise was recorded with an increase in the weathering crust thickness. Geophysical signs of the boundaries between geological structures and artificial underground objects are revealed. The exact position and depth of the old underground tunnel of Glubochinsky hydraulic structures was determined.

Geoelectric Monitoring of the Electric Potential Field of the Lower Rio Grande before, during, and after Intermittent Streamflow, May–October, 2022

Understanding the intermittent hydraulic connectivity between ephemeral streams and alluvial aquifers is a key challenge for managing water resources in arid environments. The lower Rio Grande flows for short, discontinuous periods during the irrigation season through the Mesilla Basin in southeastern New Mexico and southwestern Texas. Hydraulic connections between the Rio Grande and the Rio Grande alluvial aquifer in the Mesilla Basin vary spatially and temporally and are not well understood. Self-potential (SP) monitoring and time-lapse electric resistivity tomography (ERT) were therefore performed along linear cross-sections spanning the riverbed and flood plain for more than 4 months to monitor the transient hydraulic connection between the river and the alluvial aquifer by measuring time-lapse changes in the electric potential field in the riverbed and flood plain. The monitoring period began on 21 May 2022, when the riverbed was completely dry, continued through the irrigation season while streamflow was provided by reservoir releases from upstream dams, and ended on 4 October 2022, when the riverbed was again dry. SP monitoring data show (1) a background condition in the dry riverbed consisting of (a) a positive electric potential anomaly with a maximum amplitude of about +100 mV attributed predominantly to a subsurface vertical salt concentration gradient and (b) diurnal electric potential fluctuations with amplitudes of 40,000–90,000 mV attributed to near-surface heat conduction driven by weather variability, in addition to (2) a streaming potential anomaly during the irrigation season with a maximum amplitude of about −3500 mV whose transient behavior clearly exhibited a change from the background anomaly to depict exclusively losing streamflow conditions that persisted through the irrigation season. Time-lapse ERT monitoring results depict rapid infiltration of streamflow into the subsurface and imply the river and Rio Grande alluvial aquifer established a full hydraulic connection within a few hours after streamflow arrival at the monitoring site. SP monitoring data show an apparent transition from hydraulic connection to disconnection at the end of the irrigation season and indicate that the transitional phase between connection and disconnection may last substantially longer than the transition from disconnection to connection. The combination of SP and ERT monitoring demonstrated herein shows the potential for broader applications of time-lapse monitoring of hydraulic intermittency and near-surface heat fluxes in different rivers.

Deep low-salinity groundwater in sedimentary basins: petrophysical methods from a case study in Somalia

Oil and gas exploration data for the Northern Somalia and Horn of Africa region have been utilised for deep freshwater resources exploration. This unique geophysical and petrophysical dataset is integrated into a regional hydrogeological study and it allows for targeting of unmapped and unknown deep aquifers that would otherwise be beyond the conventional reach of the groundwater sector. The database includes open-hole well logging surveys (resistivity, gamma ray, and spontaneous potential), mud logging and drill stem test (DST) data. The results from the data analysis are combined with the geological interpretation to assess the freshwater potential of each mapped hydrostratigraphic unit in the region. The results highlight the presence of several previously unknown deep low-to-medium salinity (<9 g/L total dissolved solids (TDS)) aquifers within the Jurassic to Eocene units, including the Adigrat, Hamanlei, Gabredarre, Gumburo, Jessoma, and Auradu formations. With tested intervals of water containing less than 3.8 g/L total dissolved solids, the Auradu, Jessoma, and Gumburo formations are the most promising deep freshwater aquifers. Additional results on the analysis of groundwater parameters, such as hydraulic head, provide the basis for further groundwater modelling. The results show that the method has good potential, in particular for use in drought-stricken areas of arid regions. Ultimately, the results from this region have global significance, as the method can provide a new means of boosting fresh groundwater resources in water-poor regions, and supporting sustainable development and utilization of the resources in the medium and long term.

A review on theory, modeling, inversion, and application of self-potential in marine mineral exploration

The self-potential (SP) method is one of the passive geophysical exploration techniques, which employs measurements of naturally occurring electric potential differences on the ground surface and in boreholes or (sea-)water due to causative sources from electrochemical, electrokinetic, and thermoelectric mechanisms. SP signals are directly related to groundwater flow and (electro-)chemical gradient. There has been increasing interest in the application of SP measurements in mineral exploration, environmental surveys, and hydrogeophysical problems. This review focuses primarily on the theory concerning the causative source mechanism, numerical modeling, and inversion and interpretation of SP signals related to ore bodies and applications in mineral exploration. Three field examples focusing on seafloor sulfide deposits exploration are summarized to show the application effect of SP measurements in marine mineral exploration. This study would be helpful to investigating the use of SP surveys in ore prospecting, especially in marine environments.

Machine learning algorithm optimization for intelligent prediction of rock thermal conductivity: A case study from a whole-cored scientific drilling borehole

Rock thermal conductivity (TC) is a key parameter in geothermal, petroleum geology, and basin research. Although experimental analysis relying on core samples is currently an effective way to obtain the TC of rocks, it is not always feasible as most boreholes have no or limited cores, making it difficult to establish TC model of geological body efficiently and accurately. This study sheds light on how machine learning algorithms can be used to accurately predict rock TC with easily accessible and high-resolution logging data. Based on 295 measured TC data, logging data, and vertical seismic profile (VSP) data collected from the whole-cored CSDP-2 borehole, the models including random forest (RF), convolutional neural network (CNN), support vector regression (SVR), and particle swarm optimization-SVR (PSO_SVR), were applied to predict the TC of the entire borehole section. Using a confusion matrix analysis, the primary-wave velocity (PWV) from the VSP survey, measured density, and logging data, including shallow lateral resistivity (LLS), compensated neutron log (CNL), density (DEN), gamma rays (GR), spontaneous potential (SP), and acoustic transit time (AC), were used as the input variables for training models and TC prediction. The results showed that the geophysical parameters reflecting those properties related to mineral composition, porosity and reservoir fluids of geological body can be well used to predict TC through machine learning algorithms. Regardless of unconsolidated sediments or rocks, the RF model showed stronger applicability and higher accuracy in TC prediction compared to the PSO_SVR and CNN models, while the SVR model showed poor applicability in this case study. The PWV data can effectively improve the accuracy of TC prediction of all models, and the RF model finally yielded the excellent performance with a correlation coefficient (> 0.86) and root mean squared error (8%) between the predicted and measured values. Future research should focus on studying the weighted analysis for the correlation between geophysical parameters and TC and developing more accurate predictive models for wider applications.

Литофациальная интерпретация сеноманских отложений на севере западно-сибирского нефтегазоносного бассейна

The lithofacies of the Cenomanian succession within a gas field in the north of the West Siberian basin were studied using well log information especially spontaneous potential log to determine the lithostratigraphy, hydrodynamic characteristics, possible reservoir sands and depositional environment of the study area for opportunities that will support the exploration program. Geophysical well logs from six profile wells were used for this study. The lithostratigraphic model and sequence-stratigraphic frame were developed using spontaneous potential log curves to identify lithic units like sand, silt and mud. The depositional environments penetrated by the wells interpreted from log signatures gave four main types of lithofacies: Foreshore, Regressive Shoreface; Transgressive Shoreface; Discontinuous Currents were recognized from the stacking patterns of the spontaneous potential curves by modified electro facies classification. The stratigraphic column of the wells was subdivided into parasequences composing four sequences within the regional stratigraphic trend.

Estimation of Leachate Distribution Around the Bakau Besar Landfill in Mempawah Regency Using the Self-Potential Method

Leachate is a liquid that seeps into piles of garbage and can carry dissolved materials resulting from the decomposition process of the waste. The leachate distribution can cause groundwater contamination around the landfill. This study aims to map leachate distribution around the landfill of Bakau Besar in Mempawah Regency. Identification of leachate flow is carried out based on the distribution of potential values on the surface using the self-potential (SP) method. Measurements were carried out in a fixed-base configuration using two electrodes, one electrode at the reference point (base) and the other electrode was moving along the track (rover) to measure the potential value at the measurement point. Measurements in the field apply six lines with a length of 150 m each. The distance between the lines is 10 m, and the electrode distance is 10 m. The results showed that the potential value obtained was -17.5 mV to 12.86 mV. The accumulation of leachate flow is interpreted as having a relatively low potential value. In addition, the high potential is located in the north, while the low potential is in the south of the study site. Thus, the leachate flow is thought to have accumulated in the south near the landfill of Bakau Besar.

Alterations in the properties of the glutamatergic system of the rat hippocampus in a lithium-pilocarpine model of temporal lobe epilepsy

Status epilepticus (SE) triggers many pathological changes in the nervous system that are not yet fully understood and may lead to the development of epilepsy. In this work, we studied the effects of SE on the properties of excitatory glutamatergic transmission in the hippocampus in a rat model of lithium-pilocarpine temporal lobe epilepsy. Studies were performed 1 day (acute phase of the model), 3 and 7 days (latent phase), and 30 to 80 days (chronic phase) after SE. Using real-time PCR, we found that in the latent phase there is a decrease in gene expression of GluA1 and GluA2 AMPA receptor subunits, which may also be accompanied by an increased proportion of calcium-permeable AMPA receptors, which play an essential role in the pathogenesis of many CNS diseases. In acute brain slices we found a decrease in the efficiency of excitatory synaptic neurotransmission in all phases of the model when recording field responses in the CA1 region of the hippocampus in response to stimulation of Schaffer collaterals by electric currents of different intensities. However, in the chronic phase we found an increase in the frequency of spontaneous excitatory postsynaptic potentials, indicating an increased background activity of the glutamatergic system in epilepsy. This is also supported by a decrease in the threshold of hind limb extension in the test of maximal electroshock seizure in rats with temporal lobe epilepsy compared to control animals. The results obtained indicate the presence of a number of functional alterations in the glutamatergic system related to epilepsy. These findings can be used to develop antiepileptogenic therapy.

Representing the Unrepresentable

This article discusses the representations of alienhood in a selection of first contact science-fiction films. It performs a cinematographic reading of human encounters with and attitudes towards alienhood. By examining the visual stylistic choices, the representation of outer-space (other)worlds and alienhood will be problematized beyond the binarism of vilification and celebration. Instead, contact with alienhood will offer deeper insight into the cultural, intellectual and psychological facets of human identity and urge further introspection about the human position in a universe that no longer obeys an anthropocentric logic. Ultimately, first contact science-fiction cinema will be shown to relativize the reassuring conception of selfhood and to suggest the obsolescence of universalist-humanist assumptions about alienhood. This is achieved by opting for a representational one-way route which leads towards acceptance, not of the alien per se, but of the potential and limits of the human self when faced with the unknowability and the unrepresentability of alienhood.

Alterations in the Properties of the Rat Hippocampus Glutamatergic System in the Lithium-Pilocarpine Model of Temporal Lobe Epilepsy

Status epilepticus (SE) triggers many not yet fully understood pathological changes in the nervous system that can lead to the development of epilepsy. In this work, we studied the effects of SE on the properties of excitatory glutamatergic transmission in the hippocampus in the lithium-pilocarpine model of temporal lobe epilepsy in rats. The studies were performed 1 day (acute phase), 3 and 7 days (latent phase), and 30 to 80 days (chronic phase) after SE. According to RT-qPCR data, expression of the genes coding for the AMPA receptor subunits GluA1 and GluA2 was downregulated in the latent phase, which may lead to the increased proportion of calcium-permeable AMPA receptors that play an essential role in the pathogenesis of many CNS diseases. The efficiency of excitatory synaptic neurotransmission in acute brain slices was decreased in all phases of the model, as determined by recording field responses in the CA1 region of the hippocampus in response to the stimulation of Schaffer collaterals by electric current of different strengths. However, the frequency of spontaneous excitatory postsynaptic potentials increased in the chronic phase, indicating an increased background activity of the glutamatergic system in epilepsy. This was also evidenced by a decrease in the threshold current causing hindlimb extension in the maximal electroshock seizure threshold test in rats with temporal lobe epilepsy compared to the control animals. The results suggest a series of functional changes in the properties of glutamatergic system associated with the epilepsy development and can be used to develop the antiepileptogenic therapy.

Sequence architecture, depositional system evolution and controlling factors in a lacustrine basin: a case study from Changdi Area, Bohai Bay Basin, Eastern China

AbstractThe Paleogene Shahejie and Dongying formations of the eastern Bohai Bay Basin contain &amp;gt;500 m fluvial-deltaic deposits and &amp;gt;600 m deltaic-lacustrine deposits, both of which are important for oil and gas exploration. This study aims to figure out the deposition system distribution within the sequence stratigraphy and predict the exploration target. Sequence boundaries are recognized by unconformities in the seismic profiles and abrupt changes in the well-logging curves (acoustic, spontaneous potential, natural gamma-ray and resistivity), and two second-order and five third-order sequences (SQs1, SQs3 in the Shahejie Formation and SQd1-SQd3 in Dongying Formation) are identified. Four types of depositional system and distribution are determined by well-logging profiles, cores, relative sand content and root-mean-square seismic attributes. The SQs3 sequence is predominantly fan deltas and lacustrine deposits, the SQs1 sequence is predominantly shallow lacustrine deposits, the SQd3 sequence is predominantly braided-river delta, semi-deep lacustrine, and turbidite fan, and the SQd2 sequence is predominantly braided-river delta deposits, whereas the SQd1 sequence is predominantly braided-river deposits. The controlling factors are determined by basin subsidence simulation and fossil data of biological palynology, indicating that tectonic activity is the main controlling factor in SQs3 and SQd3 while climate is the main controlling factor in the SQs1, SQd2 and SQd1 sequences. Combined with the physical properties of sandstone, it is concluded that the beach bar in the SQs1 sequence, turbidite fan in the SQs3 and SQd3 sequences, and thick sandstone in the SQd2 sequence are the important exploration targets.

Correction to: Statistical analysis for biogeochemical processes in a sandy column with dynamic hydrologic regimes using spectral induced polarization (SIP) and self-potential (SP)

Correction to: Statistical analysis for biogeochemical processes in a sandy column with dynamic hydrologic regimes using spectral induced polarization (SIP) and self-potential (SP)

Mitochondrial ROS as a regulator of synaptic function.

Exacerbated emission of reactive oxygen species (ROS) from presynaptic mitochondria is a well-studied hallmark of several neurodegenerative diseases, including amyotrophic lateral sclerosis. Outside of the context of disease, the potential role of mitochondrial ROS in presynaptic function and plasticity remains largely understudied. Here, we investigated this potential role by combining electrophysiological recordings, confocal imaging, immunohistochemical staining, and optogenetics using a well-established protocol for induction and measurement of synaptic potentiation in drosophila neuromuscular preparations. We have previously found that optogenetic induction of ROS emission from presynaptic mitochondria expressing mito-killer red was accompanied by an increase in spontaneous mini junction potentials. The increase in electrical activity did not appear to be associated with major synaptic structure alterations such as the formation of presynaptic filopodia or the growth of ghost boutons. However, in existing boutons, we observed an increase in active zone markers such as nc82/Brp. We have not detected Wnt1/Wg release from synaptic boutons suggesting the involvement of other signaling pathways that underlie observed changes in electrophysiological activity mediated by ROS emission. Future studies will further inquire the role of mitochondrial ROS in synaptic potentiation, as well as the potential signaling targets of mitochondrial ROS in the presynaptic structure.

Determination of groundwater potential using electrical resistivity survey and borehole logging in sites I and III of Delta State University, Abraka Nigeria

This study examines the aquifer properties and lithological structure of Abraka, Nigeria, specifically the Delta State University Site I and III environs. Ten Schlumberger geoelectric soundings, geophysical well logging and pumping test method were employed using an ABEM Terrameter. A drilled water well and existing borehole data were used for this study. The result of the lithological study revealed that the subsurface formations consist of topsoil, lateritic sand, fine and medium grain sand mixed with clay. The topsoil is brownish with thickness of 2 m, the laterite is reddish with thickness of 4 m, the fine sand is whitish with thickness of 10 m, and the medium sand is also whitish with thickness &gt;12 m. The results of the evaluation of the geoelectric data using curve matching and Win Resist computer iteration was in strong agreement with that of the well record, with a subsurface that is composed of 4 to 6 geo-electric layers. The depth ranges from 13.5m to 97.8m while the resistivity ranges from 1021.2 Ωm to 9092.4 Ωm. A core soil sample collected at an interval of 5m, spontaneous potential and resistivity logs were carried out on the well. The hydraulic conductivity, well's transmissivity, storativity, and specific capacity are 102.7m2/day, 5.14 m/day, 0.00062 and 0.39 m3/m respectively. It is recommended that a drill depth of 30 m and above should be accessed for potable water in the area. From the result of this survey, we infer that this aquifer is confined and capable of supplying the people with adequate and good quality drinking water.

Base-Level Fluctuation Controls on Migration of Delta Lobes: A Case Study from the Paleogene Shahejie Formation in the Huimin Depression, Bohai Bay Basin, NE China

Sandbody distribution patterns and controls are the most important foundation for petroleum exploration and development, particularly in a lacustrine basin with rapid changes in the sedimentary environment. To provide sedimentologists and petroleum geologists around the world with an analogue for sandstone reservoir prediction, the sedimentary facies of the fourth member of the Shahejie Formation (Sha-4 Member) in the Huimin Depression of the Bohai Bay Basin were analyzed, and the sequence stratigraphic framework was established based on characteristics of spontaneous potential logs and lithology. According to the findings of this study, the Sha-4 Member’s sedimentary environment was dominated by delta front and shallow lake facies. Delta front sandbodies were discovered to retrograde before prograding again throughout the established profile. The Sha-4 Member in the Huimin Depression is divided into a third-order sequence (LSC1), which can be further divided into four fourth-order sequences (MSC1 to MSC4), corresponding to the four sub-members (S4-1 to S4-4). During the development of the MSC1 to MSC4 sequences, the delta depositional scale first decreased and then increased with the changing base level. The maximum flooding surface developed within the MSC3 sequence. The Sha-4 Member sequence model reveals that the deltas in the study area exhibit self-similarity, and delta sandbodies are primarily developed in the MSC1, MSC2, and MSC4, whereas mudstone is largely developed in the MSC3.

REVIEW OF IDENTIFIED SHORTCOMINGS IN AQUIFER VULNERABILITY ASSESSMENTS

Several studies have successfully carried out aquifer vulnerability evaluations using a combination of geophysical and biogeochemical methods. Unfortunately, some identified shortcomings have often led to inaccurate assessments. This review attempts to identify some of these drawbacks and suggest better ways to improve upon analysis and interpretation of results. Articles reviewed were sourced publicly and subjected to systematic analysis based on fundamental principles. The outcomes of each analysis were discussed, among which was a study that applied Ohmega Resistivity meter to acquire Self-Potential (SP) data without specifying the nature of electrode used. The result indicated large SP readings ≥200mV attributed to high fluid flow. According to analysis, when copper stakes are used, spurious SP readings occur in contrast to lower SP values of roughly 10 mV when suitable non-polarizable electrodes of Cu/CuSO4 porous pots are utilized to collect SP data. The review made clear the importance of providing detailed explanation of the nature of materials used. Another study solely collected samples for groundwater quality assessments during dry season, ignoring the effects of seasonal variation on water parameters. This must have had an impact on the results of the investigations. Research examined the aquifer problems in Gosa area of Abuja, utilizing only the Vertical Electrical Sounding (VES) technique. The study suggested basaltic intrusion as probable cause of borehole failures in the area. A different research which incorporated VES and data from the hill-shaded Shuttle Radar Topography Mission (SRTM), suggested insufficient interconnectivity within the fractures as conditions controlling groundwater occurrence in the area. The study illustrated the need for integrating geophysical methods for effective target detection. To map the infiltration of leachate into the subsurface, a study applied only the VES technique. Studies, however, showed that the VES method only provided average resistivity readings, suppressing some features. The study suggested the combination of VES and 2-D imaging for more accurate results. Another study obtained data via the ADMT Groundwater Detector. At the interpretation stage, the author interpreted ADMT data as VES, which was perceived as inaccurate as their principles and methodologies are different. Another study was noted to have presented results without categorizing the Aquifer Protective Capacity (APC) rating in percentages (%). It was assessed that a framework that accurately categorized the APC of each transversal using common statistics guidelines would have made it simpler to understand and aided decision-making. Future research is advised to take some of the noted flaws into account in order to enhance data processing and interpretation.

Fully desktop fabricated flexible graphene electrocorticography (ECoG) arrays

Objective: Flexible Electrocorticography (ECoG) electrode arrays that conform to the cortical surface and record surface field potentials from multiple brain regions provide unique insights into how computations occurring in distributed brain regions mediate behavior. Specialized microfabrication methods are required to produce flexible ECoG devices with high-density electrode arrays. However, these fabrication methods are challenging for scientists without access to cleanroom fabrication equipment. Results: Here we present a fully desktop fabricated flexible graphene ECoG array. First, we synthesized a stable, conductive ink via liquid exfoliation of Graphene in Cyrene. Next, we established a stencil-printing process for patterning the graphene ink via laser-cut stencils on flexible polyimide substrates. Benchtop tests indicate that the graphene electrodes have good conductivity of ∼1.1 × 103 S cm−1, flexibility to maintain their electrical connection under static bending, and electrochemical stability in a 15 d accelerated corrosion test. Chronically implanted graphene ECoG devices remain fully functional for up to 180 d, with average in vivo impedances of 24.72 ± 95.23 kΩ at 1 kHz. The ECoG device can measure spontaneous surface field potentials from mice under awake and anesthetized states and sensory stimulus-evoked responses. Significance: The stencil-printing fabrication process can be used to create Graphene ECoG devices with customized electrode layouts within 24 h using commonly available laboratory equipment.

A Comparative Study on Appraisal of Lithological Boundaries and Litho-Models Using Well Log Data at Bhogpara Oil Field in Assam of NE India

Accurate assessment of bed boundaries at a drill site is a crucial step for reservoir characterization. Generally, the interpreters in oil industries carry out such analysis through expensive softwares based on their experiences and geological knowledge in the study area. However, identifying bed boundaries using traditional interpretation is tedious. In this study, we adopted a synergistic approach of Walsh transform and a bed boundary demarcation technique to discriminate the lithological boundaries in Bhogpara oil field of Assam in NE India. This bed boundary detection technique was tested over self-potential (SP), gamma ray (GR) and laterolog deep resistivity (LLD) logs. Initially, we detected the possible lithological boundaries from GR log variations and hence proposed a lithological model as per the knowledge of traditional log interpretation techniques. Subsequently, Walsh low pass filter was applied to the self-potential (SP), GR and LLD logs to obtain their step function. Afterward, the step functions of logs were processed through the boundary detection algorithm to find out the possible thick and thin beds. Further, bed correlation was made among the Walsh-detected boundaries for the studied wells of the Bhogpara oil field. Finally, a bed boundary model was generated using the boundaries picked from the Walsh-based approach. Our analysis exhibit that the model generated from Walsh boundaries more explicitly envisaged the possible heterogeneity. Traditionally we discriminated the minimum bed thickness of the order of 5.15 m, whereas, from the Walsh-based approach we obtained thin bed of the order of 3.2 m. This proposed bed boundary assessment technique is also helpful in understanding the position of subsurface rock layers as well as possible thick and thin beds when we don’t have any pre-received core information.

Electric field stimulation boosts neuronal differentiation of neural stem cells for spinal cord injury treatment via PI3K/Akt/GSK-3β/β-catenin activation

BackgroundNeural stem cells (NSCs) are considered as candidates for cell replacement therapy in many neurological disorders. However, the propensity for their differentiation to proceed more glial rather than neuronal phenotypes in pathological conditions limits positive outcomes of reparative transplantation. Exogenous physical stimulation to favor the neuronal differentiation of NSCs without extra chemical side effect could alleviate the problem, providing a safe and highly efficient cell therapy to accelerate neurological recovery following neuronal injuries.ResultsWith 7-day physiological electric field (EF) stimulation at 100 mV/mm, we recorded the boosted neuronal differentiation of NSCs, comparing to the non-EF treated cells with 2.3-fold higher MAP2 positive cell ratio, 1.6-fold longer neuronal process and 2.4-fold higher cells ratio with neuronal spontaneous action potential. While with the classical medium induction, the neuronal spontaneous potential may only achieve after 21-day induction. Deficiency of either PI3Kγ or β-catenin abolished the above improvement, demonstrating the requirement of the PI3K/Akt/GSK-3β/β-catenin cascade activation in the physiological EF stimulation boosted neuronal differentiation of NSCs. When transplanted into the spinal cord injury (SCI) modelled mice, these EF pre-stimulated NSCs were recorded to develop twofold higher proportion of neurons, comparing to the non-EF treated NSCs. Along with the boosted neuronal differentiation following transplantation, we also recorded the improved neurogenesis in the impacted spinal cord and the significantly benefitted hind limp motor function repair of the SCI mice.ConclusionsIn conclusion, we demonstrated physiological EF stimulation as an efficient method to boost the neuronal differentiation of NSCs via the PI3K/Akt/GSK-3β/β-catenin activation. Pre-treatment with the EF stimulation induction before NSCs transplantation would notably improve the therapeutic outcome for neurogenesis and neurofunction recovery of SCI.

An Improved Computational Learning-Based Model for Estimating Total Organic Carbon in Unconventional Shale Reservoirs

Unconventional resources have emerged as one of the crucial alternatives to the rapidly depleting of conventional hydrocarbon resources. The hydrocarbon potential of shale source rocks is assessed by the percentage of the organic index such as total organic carbon (TOC). Correct estimation of TOC is very important since minor deviations in anticipated results can lead to wastage of investments and time. A slight improvement in estimation practices, on the other hand, can increase the value of an exploration project. Therefore, the objective of this study is to present an improved classification and regression tree (CART) computational learning-based model as an improved alternative in estimating TOC from well logging data. Conventional well logs suite of bulk density, gamma-ray, deep resistivity, sonic transit time, spontaneous potential, and neutron porosity from Mihambia, Mbuo and, Nondwa, Formations of the Mandawa Basin Tanzania, were used as input variables. Results from the developed CART TOC model were compared with the random forest (RF) and backpropagation neural network (BPNN). It was observed that the proposed CART model trained better while generalizing better through unused testing data compared with RF and BPNN. CART model achieved R, RMSE, and MAPE values of 0.9615, 0.0840, and 0.5035 for training and 0.9703, 0.1162, and 0.3722 for testing respectively. The proposed model work with higher accuracy with the sensitivity analysis indicating that gamma-ray, deep resistivity, and sonic transit time significantly influenced the model outcome.