High Gravity Field Research Articles

The Controlled Preparation of a Carrier-Free Nanoparticulate Formulation Composed of Curcumin and Piperine Using High-Gravity Technology.

Carrier-free nanoparticulate formulations are an advantageous platform for the oral administration of insoluble drugs with the expectation of improving their bioavailability. However, the key limitation of exploiting carrier-free nanoparticulate formulations is the controlled preparation of drug nanoparticles on the basis of rational prescription design. In the following study, we used curcumin (Cur) and piperine (Pip) as model water-insoluble drugs and developed a new method for the controlled preparation of carrier-free drug nanoparticles via multidrug co-assembly in a high-gravity environment. Encouraged by the controlled regulation of the nucleation and crystal growth rate of high-gravity technology accomplished by a rotating packed bed, co-amorphous Cur-Pip co-assembled multidrug nanoparticles with a uniform particle size of 130 nm were successfully prepared, exhibiting significantly enhanced dissolution performance and in vitro cytotoxicity. Moreover, the hydrogen bonding interactions between Cur and Pip in nanoparticles provide them with excellent re-dispersibility and storage stability. Moreover, the oral bioavailability of Cur was dramatically enhanced as a result of the smaller particle size of the co-assembled nanoparticles and the effective metabolic inhibitory effect of Pip. The present study provides a controlled approach to preparing a carrier-free nanoparticulate formulation through a multidrug co-assembly process in the high-gravity field to improve the oral bioavailability of insoluble drugs.

High-efficiency and low-consumption preparation of ultra-thin and high-performance nanotwinned copper foils by high-gravity intensified direct current electrodeposition

In study, a novel strategy was adopted by the integration of microstructure control and electrodeposition process intensification for high-efficiency, low-consumption and convenient electrodeposition of high performance and ≤4.5 μm ultra-thin copper foils for lithium-ion battery (LIB) collectors. The microstructure and the electrodeposition process of copper foils were effectively controlled and enhanced by the synergy of optimized electrolyte and Multi-Concentric Cylindrical Electrodes-Rotating Bed (MCCE-RB) which was used to generate high-gravity fields. Equiaxed nanotwinned copper (nt-Cu) foils possessed ultra-thin thicknesses ranging from 3.70 to 4.08 μm. They exhibited tensile strength and elongation of 787 MPa and 21.2 %, respectively. In contrast to the conventional direct current electrodeposition, electrodeposition and current efficiency were increased by 15.1 % and 27.2 %, respectively, while the energy consumption was decreased by 23.7 % in the high-gravity field. This is beneficial to improve the weight and energy density of LIBs by applying the strategy and technique of high-gravity intensifying.

Bearing capacity of lunar soil ground under extraterrestrial environmental effects

Lunar environment features a low gravity field and ultra-high vacuum which shows significant effects on the bearing behavior of lunar soil ground for future lunar habitation. Therefore, the 2D Discrete Element Method was employed to simulate the plate load tests under different gravity fields in non-vacuum (i.e., excluding the van der Waals force) and high-vacuum (i.e., including the van der Waals force) environments, analyzing the bearing behavior and soil response under extraterrestrial environmental effects. The results show that a bilinear line bounded by 1g can be employed to describe the gravity effect on the gravity factors for ultimate bearing capacity and coefficient of subgrade reaction. The slopes are different in low and high-gravity fields, indicating that the high-gravity effect in a centrifuge cannot be directly applied to predict the bearing behavior of lunar soil ground in a low-gravity field. The affected area becomes deeper in depth and narrower in width with the decreasing gravity level in non-vacuum environment, while the affected area becomes deeper in depth and wider in width with the decreasing gravity level in high-vacuum environment. Such observations can provide advice for developing analytical models for the bearing capacity of lunar soil ground considering the extraterrestrial environmental effects.

Enhanced electrochemical properties of nickel-cobalt hydroxide nanosheet by high-gravity liquid phase modification

Nickel-cobalt layered double hydroxide (Ni-Co LDH) nanosheet has a low specific capacity and poor rate capability. This study uses an anionic surfactant to modify Ni-Co LDH by the high-gravity liquid-phase method. The results reveal that the sodium dodecyl benzene sulfonate (SDBS) adsorption and intercalation can increase electrode interface area, enlarge interlayer spacing of Ni-Co LDH, accelerate the diffusion of electrolyte ions, and thus improve its specific capacity and rate capability. Compared with the stirred flow field, the high gravity further intensifies the surface adsorption and substitution intercalation of SDBS, resulting in a bigger interface area and interlayer spacing of Ni-Co LDH, which is more favorable to its specific capacity and rate capability. The specific capacity of Ni-Co LDH after high-gravity modification is 984 C g−1 (2187 F g−1, 2 A g−1), and its capacity retention rate reached 80 % (1–30 A g−1), significantly higher than that of the untreated one. Besides, an electrochemical kinetic study shows that a high gravity modification substantially enhances the ion diffusion rate. The modified materials under a high gravity field are utilized as anode materials and activated carbons (ACs) as cathode materials to construct supercapacitors. The Ni-Co LDHs//AC has a 50 Wh kg−1 energy density with well cycling stability. The paper proposes a high-gravity liquid-phase modification method to explore potential high-performance electrode materials.

High gravity material extrusion system and extruded polylactic acid performance enhancement

Additive manufacturing (AM) has gained significant attention in recent years owing to its ability to quickly and easily fabricate complex shapes and geometries that are difficult or impossible to achieve with traditional manufacturing methods. This study presents the development of a high-gravity material extrusion (HG-MEX) system, which generates a high-gravity field through centrifugal acceleration. In this process, the material is dissolved by heating the nozzle and subsequently deposited on the construction platform. The primary objective of this research is to evaluate the positive effects of gravity on material extrusion (MEX), which is a key aspect of AM. To accomplish this, a combined machine comprising a MEX unit and centrifuge is constructed. This HG-MEX system is used to analyze and reflect the influence of gravity on the material extrusion. The experimental evaluations demonstrate that the application of high gravity is a promising approach to improve the shape accuracy and performance of the parts fabricated through MEX. Notably, our results confirm the feasibility of utilizing MEX under high gravity to enhance performance in AM processes.

Enhancing NOx removal in a high-gravity rotating packed bed with gaseous ClO2 oxidation-absorption: Kinetic, mass transfer, and cost analysis

The application of ClO2(g) for NO oxidation presents a promising approach to improving air pollution control technology. In this study, an integration of ClO2(g) with absorption using a high-gravity rotating packed bed (HiGee RPB) was proposed for NOx removal. The results showed that ClO2(g) has a comparable oxidation efficiency (close to 100%) to O3 in converting NO to NO2, while the dosage of ClO2(g) required was two times smaller than that of O3. The gas-phase oxidation kinetic analysis between ClO2(g)-NOx, using an ideal plug flow model, simulated the potential amount of NOx species produced in a short reaction distance in the pipeline. Furthermore, at higher gas-liquid ratios and in high-gravity fields, the effective mass transfer interfacial area for NO2 absorption was mainly controlled by the liquid film rather than droplet behavior, resulting in decreased absorption capacity. The empirical model for predicting the gas-side mass transfer coefficient confirmed that the interaction between mass transfer performance and chemical absorption was independent. Therefore, selecting the appropriate absorbent is a key factor in achieving high-loading NO2 concentrations after oxidation by ClO2(g). Another interesting finding is that balancing system energy consumption and the target treated NOx concentration played a critical role in enhancing the NOx absorption capacity. The cost analysis showed that substituting existing scrubbers with RPB processes could facilitate NOx absorption capacity (g-NOx/kWh) with cost-effectiveness. Overall, this study provides valuable insights into the development of effective and efficient NOx removal technologies, and future research in this area can build on these findings.

Machine-learning-aided application of high-gravity technology to enhance ammonia recovery of fresh waste leachate

Stripping is widely applied for the removal of ammonia from fresh waste leachate. However, the development of air stripping technology is restricted by the requirements for large-scale equipment and long operation periods. This paper describes a high-gravity technology that improves ammonia stripping from actual fresh waste leachate and a machine learning approach that predicts the stripping performance under different operational parameters. The high-gravity field is implemented in a co-current-flow rotating packed bed in multi-stage cycle series mode. The eXtreme Gradient Boosting algorithm is applied to the experimental data to predict the liquid volumetric mass transfer coefficient (KLa) and removal efficiency (η) for various rotation speeds, numbers of stripping stages, gas flow rates, and liquid flow rates. Ammonia stripping under a high-gravity field achieves η = 82.73% and KLa = 5.551 × 10−4 s−1 at a pH value of 10 and ambient temperature. The results suggest that the eXtreme Gradient Boosting model provides good accuracy and predictive performance, with R2 values of 0.9923 and 0.9783 for KLa and η, respectively. The machine learning models developed in this study are combined with experimental results to provide more comprehensive information on rotating packed bed operations and more accurate predictions of KLa and η. The information mining behind the model is an important reference for the rational design of high-gravity-field-coupled ammonia stripping projects.

Fast fabrication of SnTe via a non-equilibrium method and enhanced thermoelectric properties by medium-entropy engineering

SnTe thermoelectric materials with low lattice thermal conductivity were synthesized by a self-propagating method under high-gravity field.

Preparation of Mn-FeOX/ZSM-5 by high-gravity method for heterogeneous catalytic ozonation of nitrobenzene

Mn-FeOX/ZSM-5 is a good catalyst for wastewater treatment, but the conventional methods for preparing Mn-FeOX/ZSM-5 have the problems of non-uniform dispersion of active components and long preparation time. As the liquid-solid mass transfer process could be effectively increased in a high-gravity field, Mn-FeOX/ZSM-5 was prepared by high-gravity method in this study, and its properties were characterized by XRD, FTIR and SEM. The stability of Mn-FeOX/ZSM-5 and the loss of active components were investigated, and the mechanism of Mn-FeOX/ZSM-5 catalyzed the ozonation of nitrobenzene (NB) was also discussed. The results show that the specific surface area of Mn-FeOX/ZSM-5-h is 292.103 m2/g and the active components are well dispersed. Mn-FeOX/ZSM-5-h has the best catalytic activity under the conditions of precursor solution concentration = 0.3 mol/L, liquid flow rate = 60 L/h, and high gravity factor β = 30, and the removal efficiency of TOC reaches 87.5% within 25 min. The catalyst has good stability and only 1.10% of Mn and 0.63% of Fe are lost on average after 5 cycles. However, the removal rate of NB is significantly reduced with the addition of tert-butyl alcohol (TBA), implying that ·OH plays a dominant role in catalytic ozonation of NB by Mn-FeOX/ZSM-5. The electron paramagnetic resonance results confirm that ·OH is produced in the degradation process. In conclusion, Mn-FeOX/ZSM-5-h prepared by high-gravity method is a good catalyst for catalytic ozonation of NB because of its high catalytic activity and stability.

An Improved Coastal Marine Gravity Field Based on the Mean Sea Surface Height Constraint Factor Method

Construction of a high spatial resolution and high precision marine gravity field in coastal areas is constrained by the low quality and sparse coverage of altimetry data, except for limited shipborne and airborne gravity surveys. To address this problem, a mean sea surface height constraint factor (MSSHCF) method based on the ordinary kriging method and the remove-restore technique is proposed from the perspective of interpolation. In this method, the data is standardized during the interpolation process to reduce the error and mean sea surface as variables related to the marine gravity field are added to the semi-variance function in ordinary kriging to obtain a marine gravity field with a spatial resolution of 1′ × 1′. Validation experiments show that the MSSHCF method more closely agrees with the referenced SS V28, DTU17 global marine gravity models than the ordinary kriging method. Our results were further validated against shipborne data; the accuracy of the MSSHCF method is 0.13 and 0.33 mGal higher than that of the ordinary kriging method in two experimental areas. The effects of ocean depth and offshore distance on the results were also assessed. These results show that the proposed method is more accurate than the ordinary kriging method, when the distance and depth varied. Therefore, our study demonstrates that the MSSHCF method is an innovative and feasible tool for extracting gravity fields along coastal, beach, and island areas.

Earth's gravity field and prevalence of varicose veins and chronic venous disease: Systematic review.

This study examines the influence of Earth's gravity field on the prevalence of varicose veins in geophysical area. We performed a systematic review (OVID and Google Scholar) of studies focusing on prevalence of varicose veins to determine the influence of Earth's gravity field-GRACE GGM05S gravity model-on the disease prevalence. PROSPERO: CRD42021279513. 81 studies met inclusion and quality criteria. Areas with stronger gravity have significantly higher prevalence of varicose veins with adjustment for age, gender and body mass index (BMI) (p-values < 0.02). Adjusted for age, prevalence of varicose veins in areas with gravity field +20 mGal and more is 1.37 time higher than in areas with gravity field less than +20 mGal, p-value 0.005 (95% CI: -12.5 to -2.4): mean disease prevalence for gravity field +20 mGal and more-27.5% (mean age, 40.1 years; mean gravity field, +27.1 mGal; 63.9% females, 37 studies, 123,164 participants) vs mean disease prevalence for gravity field less than +20 mGal - 20.1% (mean age, 42.2years; mean gravity field, +5.7 mGal; 56.8% females, 44 studies, 205,925 participants). Older age is the main risk factor for varicose veins (p-values < 0.005). Female gender and high BMI are insignificantly associated with high prevalence of varicose veins (p-values > 0.4 for gender, p-values > 0.2 for BMI). Stronger gravity field is significantly associated with higher prevalence of varicose veins-risk factor. The potential mechanism of this phenomenon is that high gravity field alters systemic venous return, pooling blood and fluid in the peripheral, gravity-dependent regions of the body in upright humans constantly living in the defined geophysical area.

High-gravity intensified electrodeposition for efficient removal of Cd2+ from heavy metal wastewater

Efficiently treating heavy metal wastewater are the goal that industries pursuit. A novel Multi-concentric Cylindrical Electrodes-Rotating Bed (MCCE-RB) which could provide high-gravity fields was proposed to enhance electrodeposition for efficient treatment of Cd-containing wastewater in this paper. Under the optimal operating conditions covering current density of 53.1 A m−2, wastewater circulation flowrate of 64 L h−1, high-gravity factor of 15, NaCl concentration of 0.2 mol L−1, initial pH value of 2, and initial Cd2+ concentration of 800 mg L−1, the removal efficiency of Cd2+ reached 99.4% after 120 min electrodeposition. Compared with the results of electrodeposition in normal gravity field, the removal efficiency of Cd2+, current efficiency and the mass of deposits were increased by 18.4%, 15.7% and 35.4%, respectively. The cell voltage, electrodeposition time and total energy consumption (ETotal) were decreased by 21.7%, 42% and 21.2%, respectively. SEM, EDS, XRD and XPS analyses showed that the deposits were flaky and layered structure in high-gravity fields, avoiding the formation of dendrite in normal gravity field. The deposits were comprised of the mixture of Cd and Cd(OH)2, and the percent weight of elemental Cd was 91.29% in the high-gravity field which was 19.17% higher than that in normal gravity field. The purity of Cd was improved in the high-gravity field. These was ascribed to the depressed hydrogen evolution reaction, the removal of gas bubbles from the electrodes and the improvement in mass transport in the optimal high-gravity field. High-gravity intensified electrodeposition could serve as a clean, high efficient and low energy consumption method for treating heavy metal wastewater.

Effects of high gravity on dissolution of solid modifiers in molten slag

High-gravity technology was applied to the dissolution process between molten slag and solid modifiers to accelerate the modification of hot slag. In this study, MgO and SiO2 rods were chosen as typical modifiers, and the effects of high-gravity (G = 800) and normal-gravity (G = 1) fields on the dissolution process between molten slag and solid modifiers were researched. The effects of high-gravity forces on the penetration depth and boundary layer of the dissolution process of the rod in molten slag were investigated using optical micrographs, X-ray fluorescence, X-ray diffraction, scanning electron microscopy, and electron probe microanalysis. Under high gravity conditions, the penetration depth of the slag melt into the solid rod was larger because the melt could enter deeper and smaller cracks and gaps, which increased the contact area and accelerated the dissolution process. The penetration depth increased from 0.1 mm to 1.07 mm in the MgO rod system and from 0.55 mm to 1.99 mm in the SiO2 rod system. Moreover, the boundary layer of ions between the solid rod and slag melt became thinner, which promoted the diffusion of ions; the boundary layer thicknesses were reduced from 1.91 μm to 0.45 μm in the MgO rod system and from 96.88 μm to 51.63 μm in the SiO2 rod system. In addition, high centrifugal forces could remove pores by pushing air bubbles from inner liquid–solid interfaces to the surface of the molten slag. The elimination of bubbles at the interfaces favored the penetration and dissolution processes. This study provides a rapid and effective new modification method to reduce the energy loss of molten slag and increase the output of modified slag.

Micromixing efficiency intensification of a millimeter channel reactor in the high gravity field

A millimeter channel reactor which can achieve rapid mixing has been applied in many chemical processes. To intensify the micromixing performance, previous studies focused on the structure development and the optimization of operating conditions. However, using high gravity field for micromixing performance enhancement in the millimeter channel reactor has scarcely been assessed. In this work, a novel rotating millimeter channel reactor (RMCR) was proposed, which used centrifugal and Coriolis forces to further intensify the micromixing performance. The segregation index (Xs) and micromixing time (tm) of the RMCR were experimentally studied to evaluate the micromixing efficiency. Results showed that the micromixing efficiency of the RMCR was better up to 35% than that of the conventional millimeter channel reactor without rotation by the comparsions of Xs. According to the incorporation model based on the experimental data, the value of tm in the RMCR was calculated to be 10−6–10−4 s. Furthermore, the intensification mechanism analysis illustrated that the high gravity field effectively enhanced the contact with high velocity to intensify the premixing performance. This work provides a new strategy to improve the micromixing performance in the millimeter channel reactor via high gravity field.

One-step fabrication of a bulk SnTe thermoelectric material with excellent performance through self-propagating high-temperature synthesis under a high-gravity field

One-step fabrication of bulk SnTe thermoelectric material with excellent performance through self-propagating high-temperature synthesis under high-gravity field.

SnTe thermoelectric materials with low lattice thermal conductivity synthesized by a self-propagating method under a high-gravity field.

The conventional fabrication methods (for example, melting and powder metallurgy) of bulk thermoelectric materials are time- and energy-consuming, which restrict their large-scale application. In this work, ultra-fast self-propagating synthesis under a high-gravity field was used to prepare SnTe bulks, which shortened the synthesis time from several days to a few seconds. The grain growth was suppressed and some small pores were reserved in the matrix during the ultra-fast solidification process. The increased grain boundaries and pores (nanoscale to micron scale) enhanced phonon scattering, which greatly decreased the lattice thermal conductivity. The obtained minimum lattice thermal conductivity is 0.81 W m-1 K-1, and the maximum zT value is 0.5 (873 K), which is comparable to the best reported results of the undoped SnTe alloy. The ultra-fast non-equilibrium synthesis technique opens up new possibilities to prepare high-efficiency bulk thermoelectric materials with reduced time and energy consumption.

Enhancement in fine powder availability for Powder Bed Fusion applying high gravity

In recent years, additive manufacturing (AM) technology that can directly shape objects from three-dimensional data has attractedattention.AM technology is promising as a manufacturing method in space because of its resource and space-saving properties. Some studies have shown that gravity change is viewed as a problem to overcome. On the other hand, there has been no progress in the discussion of attempts to effectively utilize gravity changes for AM technology. In this study, we focus on powder bed fusion (PBF) among AM technologies, using gravity as a control factor. The high gravity PBF (HG-PBF) is expected to be able to solve the problems of the current AM technology such as improvement of shape accuracy and process stability. In this study, we used fine powders and experimentally discuss the effect of the high gravity field on improvement of PBF process.

Microstructure and mechanical properties regulation and control of in-situ TiC reinforced CoCrFeNiAl0.2 high-entropy alloy matrix composites via high-gravity combustion route

In this study, CoCrFeNiAl0.2(TiC)x (x = 0,0.06,0.12,0.2) composites were prepared by high-gravity combustion synthesis (HGCS). The mixture powders of several low-cost metal oxides (Co2O3, Cr2O3, Fe2O3, NiO), Al, Ti and C were used as raw materials. In the high-gravity field, the CoCrFeNiAl0.2 high-entropy alloys (HEAs) were obtained by inducing a thermic reaction between the several low-cost metal oxides (Co2O3, Cr2O3, Fe2O3, NiO) and Al powders. Then the TiC was in-situ synthesized by Ti and C powders. The results show that the size and distribution of the in-situ synthesized TiC can be controlled by adjusting the Ti and C additions and the value of high-gravity field. When the high-gravity field rises to 1200 g, the bending strength, compressive strength and specific strength of CoCrFeNiAl0.2(TiC)0.12 composites respectively up to 1.17 GPa, 2.13 GPa, 0.3 MPa·Kg−1·m−3. Therefore, the HGCS with ‘green’ and efficiency characteristics offers an alternative pathway to control the structure and properties of the ceramic/ HEAs composites.

A General Strategy for Instantaneous and Continuous Synthesis of Ultrasmall Metal-Organic Framework Nanoparticles.

Ultrasmall metal-organic frameworks (MOFs) may generate unique properties to expand the scope of applications. However, the synthesis is still a great challenge. Herein, we propose a strategy to synthesize ultrasmall MOFs by high gravity technology. With the aid of tremendous intensification of molecular mixing and mass transfer in high-gravity field, six typical MOFs were obtained instantaneously in a continuous way. These samples are monodispersed with sub-5 nm in size, smaller than the previously reported values and even close to the length of one crystal unit cell. As a proof-of-concept, catalytic activity for Knoevenagel reaction can be significantly enhanced using ultrasmall ZIF-8. Conversion time of benzaldehyde was decreased by 94 % or 75 % compared to those using conventional or hierarchically porous ZIF-8. More importantly, this approach is readily scalable with the highest space-time yield for nano-MOFs, which may promote the convenient synthesis and practical applications of ultrasmall MOFs in large-scale.

Motion and dynamic analyses of a human centrifuge system with an efficient design configuration

Modern high-maneuverable fighters and airplanes can expose pilots and aircrews to high-Gravity acceleration. In order to maintain air safety and superiority during operation, pilots and aircrews should have tolerance for this intense acceleration. Countermeasures can be taken to enhance the human tolerance to high-Gravity acceleration motion fields. One of the most promising solutions is acceleration physiology training using a Human Centrifuge System (HCS). Motivated by the lack of practical guidelines on design and development of HCS's structure and control algorithms, this study introduces an analysis framework towards characterising the most feasible HCS design configuration, meeting the requirements of effective centrifuge training. The proposed framework, including Inverse Kinematic and Dynamic (IKD) operation, motion analysis and sensitivity plots, can be simply applied to different design configurations with minor modification in the kinematic and dynamic algorithm. The outcomes of the study show the dependency of kinematic and dynamic responses of the system on the design and operational parameters. It is observed that the range of Coriolis acceleration and feet-to-head acceleration ratio can be minimised by adopting a proper orientation of the gondola. This outcome can be an important step towards the design of a more efficient and affordable HCS, without imposing the over-increased HCS's arm length challenges.