Effective Volume Research Articles

Dose-Response Effect of an Inertia Flywheel Postactivation Performance Enhancement Protocol on Countermovement Jump Performance.

The purpose of this study was to investigate the dose-response effect of a high-load, 6-repetition, maximum effort inertial flywheel (IFw) squat postactivation performance enhancement (PAPE) protocol on countermovement jump (CMJ) performance metrics. Thirteen subjects completed 5 squat testing sessions: 1 session to determine back-squat 6-repetition maximum, 1 session to determine 6-repetition maximum IFw load, and 3 sessions to investigate the dose-response effect of an IFw PAPE protocol set at the load determined in the second session. In the IFw PAPE sessions, subjects completed either 1, 2, or 3 sets of IFw squats, then performed 5 CMJs over 12minutes (1, 3, 6, 9, and 12min post-IFw). All CMJ tests were conducted on a force platform where CMJ performance outcomes and impulse variables were calculated. There was no main time or volume effect for jump height, contact time, reactive strength index, peak force, or any of the impulse variables. A main time effect was identified for flight time (P = .006, effect size = 0.24) and peak power (P = .001, effect size = 0.28). The lack of change in jump height may indicate that too much fatigue was generated following this near-maximal IFw squat protocol, thereby reducing the PAPE effect.

374 Feasibility of Postoperative Diffusion Weighted Imaging to Assess Neural Recovery in Cervical Spondylotic Myelopathy

INTRODUCTION: Following decompressive surgery for cervical spondylotic myelopathy (CSM), advanced diffusion-weighted MRI, such as diffusion basis spectrum imaging (DBSI), may hold significant value by quantifying and tracking spinal cord microstructure. However, there is a paucity of studies investigating this topic, likely due to challenges in resolving signal distortions from spinal instrumentation. METHODS: A single-center prospective study enrolled 50 CSM patients and 20 control patients. All patients underwent preoperative and repeat diffusion-weighted MRI at two-year follow-up. All CSM patients underwent decompressive cervical surgery. DBSI metrics were extracted from the C3 spinal cord level only to minimize image artifact and reduce partial volume effects. DBSI anisotropic tensors evaluated white matter tracts through fractional anisotropy, axial diffusivity, radial diffusivity, and fiber fraction. DBSI isotropic tensors assessed extra-axonal pathology through restricted and non-restricted fraction. RESULTS: Of 50 CSM patients, 27 patients underwent both baseline and postoperative diffusion-weighted MRI scans with sufficient quality for analysis. This included 15 mild, 7 moderate, and 5 severe CSM patients, who were followed up to 23.2 (5.6, range 11.1-32.8) months. All preoperative C3 DBSI measures were significantly different between CSM and control patients (p < 0.001), except DBSI fractional anisotropy (p = 0.31). At two-year follow-up, the same significance pattern was found, except DBSI radial diffusivity lost statistical significance (p = 0.75). When assessing change in C3 DBSI measures, CSM patients exhibited significant decreases in DBSI radial diffusivity (p = 0.02). Among control patients, there was no significant difference in DBSI metrics between timepoints. CONCLUSIONS: DBSI may have potential in the postoperative setting to inform clinicians of white matter tract recovery after decompressive cervical surgery for CSM.

Evaluation of Lentiviral Based Gene Delivery System in Adherent and Suspension in vitro Cell Models

Lentiviruses are a highly robust gene delivery system capable of in vitro and in vivo gene transfer into multiple cell types. Recent fourth-generation lentiviral systems have been designed for enhanced safety, however, the increased recombination events required to produce infective lentiviral particles may reduce production efficiency. A set protocol for all types of target cells is not recommended and optimization of conditions for gene transfer into different target cells is required. In this study, we aim to evaluate the efficiency and reproducibility of lentiviral production using a fourth-generation lentiviral packaging system and identify optimal parameters for successful transduction in two different cell models, adherent and suspension cells. Lentiviral production, effect of viral volume, sustained gene expression and transduction adjuvants on adherent and suspension gene- cell models were evaluated. Transfection and transduction efficiency of lentiviruses was evaluated by fluorescence microscopy and flow cytometry. This study demonstrates that production of green fluorescent protein (GFP)- lentiviruses using the fourth-generation lentiviral packaging is consistent and reproducible. Optimal transduction of adherent cell types is achieved at lower multiplicity of infection (MOI) compared to suspension cells and produces GFP-expressing cells with higher intensity. Expression of GFP is sustained in all cell types over multiple passages. Polycation DEAE-dextran was determined to improve transduction in suspension cells, however, provides similar transduction efficiency as polybrene in adherent cells. In conclusion, fourth generation lentiviral system reproducibly generates high titre lentiviruses capable of infecting multiple cell types, however transduction protocols for different cell types require further optimization.

Foreign Dependency and Economic Growth Nexus in Kenya

Foreign dependency is an economic phenomenon, which is characterized by asymmetrical benefits, favouring specific countries at the expense of others, and impeding the growth potential of dependent economies. The main objective of the study was to determine the relationship between foreign dependency and economic growth in Kenya. To achieve this overarching aim, specific objectives have been delineated to include an evaluation of the effect of import volumes and external debt levels on economic growth in Kenya. The theoretical underpinnings of this study draw from several key economic theories and models, each offering unique insights into the dynamics of foreign dependency. This study employed a descriptive and inferential statistical design and leverages a time series dataset spanning the years 1980 to 2021, meticulously sourced from the World Bank. To facilitate a comprehensive analysis, the Autoregressive Distributed Lag (ARDL) model was applied. The empirical analysis revealed noteworthy relationships between determinants of economic growth in the Kenyan context. Specifically, imports of goods and services and external debt are all identified as having statistically significant impacts on the trajectory of economic growth in Kenya. In conclusion, these findings suggest that factors like imports and external debt contributes positively to economic growth. The study recommends that policymakers should explore strategies to attract productive external debt which will stimulate positive investment spillover effects within the economy. Emphasis should be placed on the need to bolster the import-led growth through regulatory mechanisms that safeguard local producers. Responsible external debt management is underscored as pivotal to fostering sustained and robust economic growth. Additionally, trade policies designed to facilitate import-led growth are posited as potentially beneficial for the Kenyan economy.

False positive findings associated with adenoviral vector-based vaccine underscore the regulatory necessity to eliminate abnormal toxicity test

Accumulating evidence has shown that the abnormal toxicity test (ATT) is not suitable as a quality control batch release test for biologics and vaccines. The purpose of the current study was to explore the optimal ATT experimental design for an adenoviral vector-based vaccine product to avoid false positive results following the standard test conditions stipulated in the Pharmacopoeias. ATT were conducted in both mice and guinea pigs based on methods in Pharmacopeias, with modifications to assess effects of dose volume and amount of virus particles (VPs). The results showed intraperitoneal (IP) dosing at human relevant dose and volume (i.e., VPs), as required by pharmacopeia study design, resulted in false positive findings not associated with extraneous contaminants of a product. Considering many gene therapy products use adeno associated virus as the platform for transgene delivery, data from this study are highly relevant in providing convincing evidence to show the ATT is inappropriate as batch release test for biologics, vaccine and gene therapy products. In conclusion, ATT, which requires unnecessary animal usage and competes for resources which otherwise can be spent on innovative medicine research, should be deleted permanently as batch release test by regulatory authorities around the world.

Amelioration of L-methionine production by Alcaligenes faecalis ATCXT3624: Empirical optimization of culture conditions

Background: L-methionine production at the industrial scale suffers from various drawbacks, including the production and separation of the L-enantiomer of the amino acid methionine by chemical production methods. This strain exhibiting resilience to feedback inhibition by L-methionine provided a promising avenue for enhanced production. The present study has tried to uplift the production rate of the amino acid by a developed L-methionine-resistant strain Alcaligenes faecalis ATCXT 3624 through surpassing feedback inhibition. Methods: Empirical optimization of all fermentation conditions was studied by observing the effects of initial pH, temperature, inoculum age, medium volume, cell density, and different micronutrients, which enhanced L-methionine production. In addition, efforts were made to find suitable nitrogen and carbon sources. Results: Eventually, 23.8±0.22 mg/mL of L-methionine was obtained under optimized fermentation conditions, which is significantly (p<0.05) higher than that produced before optimized fermentation conditions. Conclusion: Eventually, it can be assumed that the strain effectively produced the amino acid at an enhanced rate under optimized conditions.

A novel rapid generation algorithm for Representative Volume Element (RVE) in composite materials considering pore geometrical parameters

Pore defects are inevitable in the manufacturing process and significantly affect the mechanical properties of composite materials. In this work, a novel algorithm capable of concurrently generating both ellipsoidal and gourd-shaped pores in composite materials is proposed and the interference detection procedure is optimized for efficient interference detection between the generated geometrical bodies. Besides, the algorithm is integrated with RVE-based finite element (FE) simulation to explore the effects of various pore types, volumes, aspect ratios, and porosity on the elastic properties of unidirectional C/C composites. The present work provides a valuable reference for generating general pore defects and investigating their resulting effects on mechanical properties of related composite structures.

Low metal content and hierarchically porous structure of “Fabaceae-Plants” derived activated carbon for high-performance supercapacitors

Plants with naturally ordered tissues and unique cell structures have become good precursors as activated carbon (AC) electrodes for supercapacitors. The various inherent plants derived ergastic substances induce numerous impurities in ACs, seriously impeding electrochemical performance. Aiming at elevating electrochemical activities, we herein, select suitable “Fabaceae-Plants” precursors via pre-leaching and carbonization-KOH activation for purer AC supercapacitor electrodes. The inherent parenchyma tissues and intrinsic low metal ion properties ensure “Fabaceae-Plants” derived ACs have large specific surface areas (SSA) (> 3000 m2 g−1) and low self-discharge rates. After ethanol reflux, most ergastic substances were removed, leading to a lower metal ion content that meets the standard procedure in Chinese GB/T 37386-2019 codes and higher mesopore volumes due to the better KOH activation effect. The mung bean sprouts-based activated carbon (AC) prepared by ethanol reflux exhibits higher capacitance (370 F g−1 at 0.5 A g−1), excellent rate performance (81.8 % from 0.5 to 50 A g−1), and an impressively low open circuit voltage attenuation rate (19.9 mV h−1). These characteristics are attributed to the synergistic effect of low metal ion impurities and higher mesopore volumes. Hence, the “Fabaceae-Plants” derived ACs are potential materials for clean energy storage and conversion systems, and the pre-leaching strategy may propose a strategy for high value-added utilization of biomass.

Online cell pressure tracking analysis and sulfur species depositing/stripping behavior study of lithium sulfur batteries

Cell failure is easy occurring in Li-S cell. Electrolyte consumption caused by side-reactions between electrolyte and anode is one of the reasons for the cell failure, but the underlying mechanism for the cell failure is still not clear. To get insight into the electrolyte decomposition, in this work, online cell pressure tracking analysis (OCPTA) is applied to study the gassing effect caused by electrolyte decomposition reactions during charge–discharge processes and the study on depositing/stripping behavior of sulfur species performed. It is found that gassing effect is negligible in the cell with conventional ether-based electrolyte when electrolyte decomposing, but volume effect caused by sulfur species dissolution is notable. Together with the sulfur preferentially depositing on the top surface of cathode, it leads to electrolyte insufficiency on the top surface of electrodes, enhancing the risk of cell failure.

Quantitative Analysis of Diagenesis Control on the Spatial Heterogeneity of Sarvak Carbonate Formation, the Dezful Embayment of Zagros Basin, Western Iran

Summary The heterogeneity indices in conventional carbonate reservoirs are usually influenced by various diagenetic processes. The main aim of this study is to build 3D geological models of the diagenetic and heterogeneity indices addressing the role of diagenesis on spatial heterogeneity variations in the Sarvak carbonate reservoir of an Iranian oil field situated in the Dezful Embayment in the Zagros Basin. Vertical heterogeneity has been discussed in many studies, but the literature is limited on the 3D geological modeling of heterogeneity and providing spatial heterogeneity maps. In this study, we determined the main diagenetic parameters influencing the reservoir heterogeneity and constructed 3D geological models for evaluating the spatial heterogeneity. A couple of heterogeneity indices including the coefficients of variation (CVs) of porosity and permeability, Lorenz coefficient, and Dykstra-Parsons coefficient in cored intervals along with some diagenetic parameters were calculated and modeled. This study shows that lateral heterogeneity is mappable and correlatable with different diagenetic overprints along with shale volume, which controls the reservoir quality and spatial heterogeneity. It also indicates that lateral trends of the heterogeneity indices in different zones of the studied reservoir are influenced by other diagenetic parameters such as secondary porosity (SPI), dolomitization, cementation, and velocity deviation log (VDL, as a diagenetic index). Different diagenetic parameters control reservoir heterogeneity in each zone by decreasing or increasing the degree of the heterogeneity, some of which have dual constructive or destructive effects on heterogeneity indices. Moreover, the results show that the effect of shale volume on reservoir heterogeneity is significant, especially when the amount of the shale volume is notable.

Semi-supervised segmentation of metal-artifact contaminated industrial CT images using improved CycleGAN.

Accurate segmentation of industrial CT images is of great significance in industrial fields such as quality inspection and defect analysis. However, reconstruction of industrial CT images often suffers from typical metal artifacts caused by factors like beam hardening, scattering, statistical noise, and partial volume effects. Traditional segmentation methods are difficult to achieve precise segmentation of CT images mainly due to the presence of these metal artifacts. Furthermore, acquiring paired CT image data required by fully supervised networks proves to be extremely challenging. To address these issues, this paper introduces an improved CycleGAN approach for achieving semi-supervised segmentation of industrial CT images. This method not only eliminates the need for removing metal artifacts and noise, but also enables the direct conversion of metal artifact-contaminated images into segmented images without the requirement of paired data. The average values of quantitative assessment of image segmentation performance can reach 0.96645 for Dice Similarity Coefficient(Dice) and 0.93718 for Intersection over Union(IoU). In comparison to traditional segmentation methods, it presents significant improvements in both quantitative metrics and visual quality, provides valuable insights for further research.

Carbon nanotubes anchored SiOx composite anode for high cyclic stability lithium-ion batteries

Silicon suboxide (SiOx, 0 < x < 2) is one of the most promising anode materials because of its high lithium-ion storage capacity. However, the poor intrinsic conductivity and large volume change during cycling limits its practical application as lithium-ion battery anode materials. Herein, we propose a novel strategy to introduce carbon nanotubes (CNTs) on the SiOx particles, forming a conductive network and relieving the volume expansion effect, which possess improved reversible capacity and robust structure for long cycling stability. The SiOx/CNT composite anode delivers reversible capacity of 1533.8 mAh g−1 at the first cycle and maintains 599.6 mAh g−1 after 500 cycles with a high coulombic efficiency of 99.7 %. In this paper, SiOx composite anchored by CNTs was prepared, which is a simple and effective strategy to improve the conductivity of SiOx, relieve the volume effect and further promote its electrochemical performance benefit from the high conductivity and structural stability of CNTs. This research provides a significant reference for constructing the delicate structure of SiOx-based composites to enhance cyclic performance.

Cyclic liquefaction in transitional and non-transitional tailings

Tailings have previously been identified as having the types of mixed mineralogies and gradings that can make them susceptible to having non-unique critical states and normally compressed states in laboratory element tests. This paper addresses how this mode of behaviour would affect their resistance to undrained cyclic loading, contrasting two triaxial studies, one on a tailings that has a conventional behaviour and one transitional. To demonstrate the influence of transitional behaviour it was necessary to create samples with as wide a range of initial specific volumes as possible, while trying keep the sample preparation methods the same for loose and dense samples. It was also necessary to examine the cyclic data in non-conventional ways, notably in the volumetric plane to highlight better the effects of initial sample specific volume. It is shown that, as previously determined for monotonic loading, the initial density has much less influence on the cyclic behaviour of a soil with transitional behaviour than it would for a conventional soil, and it is instead the stress history that is very much more important. Samples following their respective normal compression lines exhibit similar behaviour, but overconsolidation significantly enhances resistance and a sample that arrives at a given state by the undrained reduction of p′ due to cycling also has a much higher resistance.

Conductive copper ion-reinforced sodium alginate aerogel based free-standing Si anode for Li-ion storage

Biomass materials with great advantages of wide accessibility, low cost and environmental benignity have favorable application prospects as Si anodes for lithium-ion batteries (LIBs). In order to alleviate the volume effect and improve the conductance of Si, we fabricated a conductive copper ion-reinforced sodium alginate (SA) aerogel based free-standing Si anode (Si@CNTs/Alg-Cu-II) containing silicon nanoparticles, sodium alginate aerogel, carbon nanotubes and Cu nanoparticles, via a simple, low-cost and sustainable process (under 1 × 10−1 Pa, 1 °C/min to 200 °C holding for 1 h). In the irregular lamellar porous aerogel, silicon particles with good dispersion are bound by macromolecular chains of SA via dynamic hydrogen bonds and subsequently restrained in the porous aerogel to release volume stress. The in situ generated Cu particles and well-dispersed carbon nanotubes (CNTs) construct the conductive network around Si particles to improve the electrical conductivity of the electrode. This unique structure delivers a capacity of 835.6 mAh/g after 100 cycles at 0.1 A/g based on the total mass of Si@CNTs/Alg-Cu-II composite (Si content of 25.62%). Moreover, it also shows outstanding stability under high current density (a capacity retention of 84.1% after 100 cycles at 0.5 A/g). The sustainable preparation method and excellent electrochemical performance of Si@CNTs/Alg-Cu-II provide a new strategy to develop high-performance free-standing Si-based anodes for LIBs.

Image quality evaluation for a clinical organ-targeted PET camera.

A newly developed clinical organ-targeted Positron Emission Tomography (PET) system (also known as Radialis PET) is tested with a set of standardized and custom tests previously used to evaluate the performance of Positron Emission Mammography (PEM) systems. Imaging characteristics impacting standardized uptake value (SUV) and detectability of small lesions, namely spatial resolution, linearity, uniformity, and recovery coefficients, are evaluated. In-plane spatial resolution was measured as 2.3 mm ± 0.1 mm, spatial accuracy was 0.1 mm, and uniformity measured with flood field and NEMA NU-4 phantom was 11.7% and 8.3% respectively. Selected clinical images are provided as reference to the imaging capabilities under different clinical conditions such as reduced activity of 2-[fluorine-18]-fluoro-2-deoxy-D-glucose (18F-FDG) and time-delayed acquisitions. SUV measurements were performed for selected clinical acquisitions to demonstrate a capability for quantitative image assessment of different types of cancer including for invasive lobular carcinoma with comparatively low metabolic activity. Quantitative imaging performance assessment with phantoms demonstrates improved contrast recovery and spill-over ratio for this PET technology when compared to other commercial organ-dedicated PET systems with similar spatial resolution. Recovery coefficients were measured to be 0.21 for the 1 mm hot rod and up to 0.89 for the 5 mm hot rod of NEMA NU-4 Image Quality phantom. Demonstrated ability to accurately reconstruct activity in tumors as small as 5 mm suggests that the Radialis PET technology may be well suited for emerging clinical applications such as image guided assessment of response to neoadjuvant systemic treatment (NST) in lesions smaller than 2 cm. Also, our results suggest that, while spatial resolution greatly influences the partial volume effect which degrades contrast recovery, optimized count rate performance and image reconstruction workflow may improve recovery coefficients for systems with comparable spatial resolution. We emphasize that recovery coefficient should be considered as a primary performance metric when a PET system is used for accurate lesion size or radiotracer uptake assessments.

Fracture conductivity and rock appearance in volcanic reservoirs treated by various stimulation techniques

Volcanic reservoirs have complex mineral compositions and highly heterogeneous physical and mechanical properties, making their stimulation quite problematic. This study aimed at clarifying acid-rock reaction and stimulation mechanisms in volcanic reservoirs using 3D scanners and conductivity testing devices. Tests on rock sample conductivity and appearance under such mainstream stimulation technologies as hydraulic fracturing, acid fracturing, and proppant-carrying acid fracturing (PCAF) were performed. The effects of proppant particle size, proppant concentration, acid volume and type, proppant-carrying acid type, and proppant-carrying acid concentration on conductivity and rock sample appearance were analyzed. The appearance of rock samples included dot-, pit-, and strip-like embeddings, as well as acid-etching pits and channels. Larger particle sizes and higher proppant concentrations produced wider propped fractures and higher flow conductivity. Due to complex mineral distribution, acid fracturing failed to produce long etched channels, and the obtained conductivity was low, with a maximum of 8 D·cm at a 5 MPa closure stress. Hydraulic fracturing and PCAF reached a maximum flow conductivity of 155 D·cm at a 5 MPa closure stress, indicating their applicability to volcanic reservoir stimulation. This work helps reveal the acid-rock reaction and stimulation mechanisms of volcanic reservoirs and provides a theoretical basis for their development.

Liver resection volume-dependent pancreatic strain following living donor hepatectomy

The liver and pancreas work together to recover homeostasis after hepatectomy. This study aimed to investigate the effect of liver resection volume on the pancreas. We collected clinical data from 336 living liver donors. They were categorized into left lateral sectionectomy (LLS), left lobectomy, and right lobectomy (RL) groups. Serum pancreatic enzymes were compared among the groups. Serum amylase values peaked on postoperative day (POD) 1. Though they quickly returned to preoperative levels on POD 3, 46% of cases showed abnormal values on POD 7 in the RL group. Serum lipase levels were highest at POD 7. Lipase values increased 5.7-fold on POD 7 in the RL group and 82% of cases showed abnormal values. The RL group’s lipase was twice that of the LLS group. A negative correlation existed between the remnant liver volume and amylase (r = − 0.326)/lipase (r = − 0.367) on POD 7. Furthermore, a significant correlation was observed between POD 7 serum bilirubin and amylase (r = 0.379)/lipase (r = 0.381) levels, indicating cooccurrence with liver and pancreatic strain. Pancreatic strain due to hepatectomy occurs in a resection/remnant liver volume-dependent manner. It would be beneficial to closely monitor pancreatic function in patients undergoing a major hepatectomy.

Excluded volume effects in the quark-mass density-dependent model: Implications for the equation of state and compact star structure

Excluded volume effects in the quark-mass density-dependent model: Implications for the equation of state and compact star structure

Nitrogen doped, carbon coated (Zn0.71Mn0.29)Se/MnSe heterostructure as an anode for a fast-charging sodium ion battery

Nitrogen-doped, carbon-coated (Zn0.71Mn0.29)Se/MnSe porous nanospheres (Zn–Mn–Se@NC) were designed via a co-precipitation method and a vapor-phase selenization strategy, which maintained a capacity of 290 mAh/g for 5 A/g after 1000 cycles and 190 mAh/g at 10 A/g. The satisfied cycling performance was due to the porous nanosphere that relieve volume effect of electrode. Furthermore, the heterogeneous interface formed by (Zn0.71Mn0.29)Se and MnSe enhances thermodynamic stability and electrochemical reaction kinetics considerably, improving the electron/Na+ transfer rate. Furthermore, Zn–Mn–Se@NC, a bimetallic selenide, exhibits superior conductivity that improves the rate capacity of the Zn–Mn–Se@NC electrode. As an anode, the long-cycle and high-rate sodium-ion batteries using the Zn–Mn–Se@NC porous nanospheres have potential applications in electronic devices.

Quantifying partial volume effect in SPECT and planar imaging: optimizing region of interest for activity concentration estimation in different sphere sizes.

To quantify the partial volume effect in single photon emission tomography (SPECT) and planar images of Carlson phantom as well as providing an optimum region of interest (ROI) required to more accurately estimate the activity concentration for different sphere sizes. 131 I solution with the 161.16 kBq/ml concentration was uniformly filled into the different spheres of Carlson phantom (cold background condition) with the diameters of 7.3, 9.2, 11.4, 14.3, 17.9, 22.4 and 29.9 mm, and there was no background activity. In the hot background condition, the spheres were filled with the solution of 131 I with the 1276.5 kBq/ml addition to the background activity concentration of 161.16 kBq/ml in all the phantoms. The spheres were mounted inside the phantom and underwent SPECT and planar images. ROI was drawn closely on the boundary of each sphere image and it was extended to extract the true count. In the cold background condition, the recovery coefficient (RC) value for SPECT images ranged between 0.8 and 1.03. However, in planar imaging, the RC value was 0.72 for the smallest sphere size and it increased for larger spheres until 0.98 for 29.9 mm. In the hot background condition, the RC value for sphere diameters larger than 20 mm was overestimated more than in the cold background condition. The ROI/size required to more accurately determine activity concentration for the cold background ranged from 1.18 to 2.7. However, in the hot background condition, this ratio varied from 1.34 to 4.05. In the quantification of partial volume effects, the spill-out effect seems to play a crucial role in the distribution of the image counts beyond the boundaries of the image pixels. However, more investigations are needed to accurately characterize limitations regarding the object size, background levels, and other factors.