Mass Characteristics Research Articles

Application of seismic methods for determining the depth of the rock mass damage zone around the excavation profile by blasting

Research and determination of the blasting damage zone around the profile of tunnels or underground structures is a platform that would serve to confirm or correct blasting parameters and underground assemblies, that is, geotechnical and main tunnel projects. From the obtained research, the stability of the excavation profile, as well as the safety risk for equipment and personnel on the construction site, would be better understood. Considering the importance of the size of the damage zone of the rock mass in terms of its influence on stability, the amount of primary support elements required to achieve the stability of the excavated space, and the additional costs of stabilization of the excavation and the safety of people and equipment, the aforementioned problem was investigated and processed for specific cases and for the rock mass characteristic for the location in question. From the described research, the change in the elastic characteristics of the rock mass and the depth of the damage zone around the tunnel excavation profile were measured and calculated.

Roadway rock burst prediction based on catastrophe theory

In order to quantitatively calculate the critical depth and critical load of mines affected by rock burst, and to achieve effective prevention and control of rock burst in coal mines, this paper proposes a mechanical model for predicting the occurrence of rock burst in coal mine roadways based on catastrophe theory. Additionally, a theoretical calculation formula for initiating rock burst is derived. The first step was to establish a mechanical analysis model, which directly correlated with the in-situ stress, physical and mechanical characteristics of the coal-rock mass, and engineering structural parameters. Following this, a mechanical instability criterion was derived for the key load-bearing circle within the surrounding rock of the roadway. In the final step, the critical depth and load for rock burst initiation were verified for 25 distinct coal mines in China that were prone to rock burst hazards. The research results demonstrate that the discrepancy between the theoretically calculated critical depth and the actual measured statistical values was less than 35%. In addition, the difference between the theoretically determined critical depth and the value calculated by Pan Yishan was less than 32%. Notably, the ratio of the theoretically calculated critical load to the uniaxial compressive strength of the coal-rock mass ranged from 0.38 to 1.93. This aligns with empirical data on rock burst occurrences, as set out in the engineering classification standards for rock masses. These research outcomes substantiated the practical utility of the proposed theory, thereby laying a robust theoretical groundwork for the quantitative control of rock burst.

Electrically conducting mixed convective nanofluid flow past a nonlinearly slender Riga plate subjected to viscous dissipation and activation energy

This paper reports the mass and energy transmission characteristics of an electrically conducting mixed convective nanofluid flow past a stretching Riga plate. An additional effect of viscous dissipation, Arrhenius activation energy and heat source is also studied. The energy and mass transmissions are evaluated by a zero-mass flux of nanoparticle and convective boundary conditions. Buongiorno’s relations are proposed for the Brownian motion and thermophoretic diffusion. The similarity substitutions are employed to derive the non-dimensional set of modeled equations. The obtained set of equations is numerically processed via parametric continuation method (PCM). Several flow factors affecting the velocity, energy, and mass distributions are graphically discussed. It has been perceived that the fluid velocity field declines with the influence of velocity power index (m), while improves with the upshot of modified Hartmann number (Q). The effect of Schmidt number and chemical reaction diminishes the concentration profile [Formula: see text]. Furthermore, the energy curve enhances with the effect of thermophoresis factor, Biot and Eckert number.

Sweeteners in Orodispersible Films: How Much is too Much?

Four natural sweeteners (sucrose, xylitol, fructose, and isomalt) were selected to examine the influence of their qualities and amounts on the characteristics of orodispersible films. Sodium carboxymethylcellulose (2% w/w) was utilized as the film-forming polymer and 1% w/w glycerol as a plasticizer. Films were produced through the solvent casting method, rendering them suitable for convenient application in community or hospital pharmacy settings. The physicochemical and optical properties of the films were analyzed, and Fourier-transform infrared analysis was carried out. All films exhibited acceptable disintegration time, uniformity of mass, thickness, and optical characteristics, with significant dependence (p<0.05) on both sweetener type and quantity. Disintegration time varied based on the employed method, as well as the characteristics and amount of sweetener. Additionally, all films maintained pH values within the oral cavity range, suggesting no potential irritancy upon administration. Fourier-transform infrared analysis confirmed the formation of the film and demonstrated compatibility between its components.

Three-dimensional damage and rupture patterns of different thicknesses of rock mass with open joints under blast loading

There are an immense number of discontinuous structural surfaces represented by tensile joints in natural rock mass, in which the thickness of tensile joints determines the form how stress wave interacts with joint surface, which has a significant influence on the fracture behavior of jointed rock mass under blast loading. Open joint specimens were prepared using 3D printing technology, an indoor 3D blasting experiment was carried out with respect to different open joint thicknesses. Through CT scanning and three-dimensional reconstruction, the rupture and the distribution patterns of three-dimensional cracks of the post-blasting specimens were compared, and the rupture characteristics of the rock masses with different open joint thicknesses under blast loading were analyzed. The blasting process of the rock masses with open joints was inverted by AUTODYN numerical simulation software, the effects of open joint thickness on the propagation of stress wave and the three-dimensional damage characteristics of rock mass were revealed. Results showed that under the blast load, the wing cracks derived from the end of the open joints are greatly affected by the thickness of the joints and as the joint thickness increases, the annular derived cracks formed on the right outer surface of the specimen gradually decrease. In case of a change in the open joint thickness, the intensity at which the stress wave diffracts and transmits through the end of the joint will be directly affected. This makes it hard for the wing cracks at the end to initiate, the distribution density of the radial tension cracks traversing through the open joint surface attenuates obviously, resulting in the decrease of the fractal dimension and the damage extent of the specimen. As the thickness of open joints increases, the blast stress wave running through the joint surface will endure a time delay and reduced intensity, the closure of the joint surface gradually reduces, and the degree of stress concentration at the end gets weak. In the course of stress wave propagation, the rock mass on the back-blast side of the joint endures the combined actions of compressive stress field, tensile and tangential stress field and compressive and tangential stress field. As the thickness of open joint increases, the time point for the back-blast side to reach the peak stress is delayed, the intensity of the composite stress field subjected to compressive and tangential stress field decreases, and the normal displacements on the near-blast side and the back-blast side of the joint follow the opposite trend.

A method for analyzing discontinuities characterization using the integration of underground drift point cloud with 3DEC software

The geometric statistical characteristics of rock mass discontinuities, such as mean trace length and intensity, cannot be measured directly and require the use of statistical tools (such as sampling lines, sampling windows, and drilling) for analysis. In this paper, we propose a method for extracting discontinuity characteristics using the 3DEC software in three-dimensional (3D) drift models (3DM). Specifically, we introduce the Surface Disk Discontinuity Model (SDDM) as a representation model for planar and linear discontinuities identified in point clouds. By importing the 3DM and SDDM into 3DEC and utilizing a multi-circular window, we calculate the mean trace lengths and two-dimensional (2D) intensity (P21). Additionally, we propose a method to estimate the three-dimensional (3D) intensity (P32), which provides a more comprehensive reflection of the discontinuous characteristics in different spatial orientations. To validate the proposed method, we apply it to the underground drift of the Jiapigou gold mine in Jilin Province to extract the geometric statistical characteristics of discontinuities. The results demonstrate that our method successfully captures the orientation, trace length, and P32 characteristics of four dominant discontinuity groups in the study area. This approach proves to be an effective technique for utilizing 3D laser scanning to obtain accurate discontinuity characteristics of rock mass.

Stability-Considered Lane Keeping Control of Commercial Vehicles Based on Improved APF Algorithm

Regarding the lane keeping system, path tracking accuracy and lateral stability at high speeds need to be taken into account especially for commercial vehicles due to the characteristics of larger mass, longer wheelbase and higher mass center. To improve the performance mentioned above comprehensively, the control strategy based on improved artificial potential field (APF) algorithm is proposed. In the paper, time to lane crossing (TLC) is introduced into the potential field function to enhance the accuracy of path tracking, meanwhile the vehicle dynamics parameters including yaw rate and lateral acceleration are chosen as the repulsive force field source. The lane keeping controller based on improved APF algorithm is designed and the stability of the control system is proved based on Lyapunov theory. In addition, adaptive inertial weight particle swarm optimization algorithm (AIWPSO) is applied to optimize the gain of each potential field function. The co-simulation results indicate that the comprehensive evaluation index respecting lane tracking accuracy and lateral stability is reduced remarkably. Finally, the proposed control strategy is verified by the HiL test. It provides a beneficial reference for dynamics control of commercial vehicles and enriches the theoretical development and practical application of artificial potential field method in the field of intelligent driving.

Associations between low muscle mass and clinical characteristics of health population in China

ObjectivesThe primary aim of this study is to discern the association between specific clinical parameters and low muscle mass (LMM). We endeavor to elucidate the determinants of LMM and the predictive potency of individual factors. MethodsIn this retrospective cross-sectional study, we encompassed 450 older adult Chinese participants (252 males and 198 females). Muscle mass quantifications were performed using bioelectrical impedance analysis. Comprehensive data encompassing demographic details (age, sex, height, and weight) and laboratory results (complete blood count, thyroid function, liver function, and renal function) were systematically recorded. Logistic regression models, coupled with receiver operating characteristic curve analytics, were employed to ascertain the variables influencing LMM and to evaluate the predictive validity of each parameter on LMM. ResultsUpon confounding adjustment for age, gender, body mass index (BMI), and free thyroxine (FT4) persisted as a determinant of LMM. Specifically, individuals with an FT4 exceeding 1.105 ng/dL exhibited a 1.803-fold increased propensity for LMM relative to those with FT4 values below the specified threshold. Incorporating age, gender, BMI, and FT4 in the diagnostic algorithm enhanced the precision of LMM. The results differ between men and women. In the male population, we can still observe that FT4 has a certain value in the diagnosis of LMM, but this phenomenon is not found in the female population. ConclusionsElevated FT4 concentrations, albeit within clinically accepted limits, are inversely associated with muscle mass. As such, FT4 could be postulated as a potential biomarker for LMM in geriatric individuals, especially in the male group.

Outcomes of Minimally Invasive Adrenalectomy for Large Adrenal Masses: A Multi-Centre Experience in Saudi Arabia.

Introduction Advancements in radiological imaging technology have increased the discovery of adrenal incidentalomas. Large adrenal tumors (LATs) are not common, and the likelihood of malignancy increases with tumor size. LATs were defined as tumors larger than four centimeters (cm) with various pathologic diagnoses.Traditionally, open adrenalectomy was considered the gold standard for LATs, but with recent advancements in minimally invasive surgery (MIS), optimum perioperative and long-term outcomes are achievable by the MIS approach.The findings presented in this paper show that even large adrenal masses measuring up to 21 centimeterscan be safely removed using a minimally invasive approach. Methodology After Institutional Review Board (IRB) approval, we reviewed medical records of adult patients who had adrenalectomies at two Saudi Arabian centers from January 2013 to February 2023. Inclusion criteria were laparoscopic or robotic adrenalectomy and adrenal lesions ≥5cm. Pediatric patients and those with open adrenalectomies were excluded. Pre-surgery, patients had imaging studies to assess mass characteristics. Pheochromocytoma patients received a 2-week adrenergic blocker treatment. Perioperative data including demographics, comorbidities, mass characteristics, surgery details, and follow-up were analyzed using SPSS-23.Patients provided informed consent and had follow-up appointments and imaging. Results Our experience involved 35 patients, 29 of whom received laparoscopic treatment and six of whom underwent robotic surgery. Of the 35 patients, more than half were females (57.1%), with a mean age of 41.7±14.9 years, the youngest and oldest participants being 16 and 73 years of age, respectively. The mean body mass index (BMI) of the participants was in the overweight range (26±6.0 kg/m2). The most common mode of presentation was incidental (42.9%), followed by hypertension (17.1%). Most patients had right-sided adrenal gland involvement (48.6%), with only four patients showing bilateral involvement. Most of the patients were classified as American Society of Anesthesiology score (ASA) 2 (40.0%) or ASA 3 (40.0%). Most of the patients were diagnosed with myelolipoma or adenoma (22.9% each) followed by pheochromocytoma (17.1%).The average estimated blood loss (EBL) was 189.3±354.6 ml for patients who underwent laparoscopic surgery and 80.0 ±34.6 ml for patients who underwent robotic surgery. The average operative room time (ORT) was 220.1±98.7 minutes (min) for laparoscopic surgery and 188.3±10.3 min for robotic surgery. One patient had to be converted from laparoscopic to open surgery due to aortic injury. The average length of stay (LOS) was 9.5±6.7days for laparoscopic treatment and 5.5±1.9 days for robotic surgery. The mean tumor size in the greatest dimension was 8.0±4.4 cm. Only one patient who underwent unilateral laparoscopy experienced perioperative complications and converted to open surgery; nine patients who underwent unilateral laparoscopy required blood transfusion, and none of the patients who underwent robotic surgery required transfusion. None of the 35 patients experienced a recurrence of their adrenal disease during the mean follow-up period which lasted around 58 months. Conclusion MIS in Saudi Arabia is growing and is a safe method for LATs, with satisfactory surgical results compared to the traditional open surgery approach. It offers advantages in terms of EBL, complications, and disease recurrence.

New insights into the South China Sea throughflow and water budget seasonal cycle: evaluation and analysis of a high-resolution configuration of the ocean model SYMPHONIE version 2.4

Abstract. The South China Sea throughflow (SCSTF) connects the South China Sea (SCS) with neighboring seas and oceans, transferring surface water of the global thermohaline circulation between the Pacific and Indian oceans. A configuration of the SYMPHONIE ocean model at high resolution (4 km) and including an explicit representation of tides is implemented over this region, and a simulation is analyzed over 2010–2018. Comparisons with in situ and satellite data and other available simulations at coarser resolution show the good performance of the model and the relevance of the high resolution for reproducing the spatial and temporal variability of the characteristics of surface dynamics and water masses over the SCS. The added value of an online computation of each term of the water, heat, and salt SCS budgets (surface, lateral oceanic and river fluxes, and internal variations) is also quantitatively demonstrated: important discards are obtained with offline computation, with relative biases of ∼40 % for lateral oceanic inflows and outflows. The SCS water volume budget, including the SCSTF, is analyzed at climatological and seasonal scales. The SCS receives on average a 4.5 Sv yearly water volume input, mainly from the Luzon Strait. It laterally releases this water to neighboring seas, mainly to the Sulu Sea through Mindoro Strait (49 %), to the East China Sea via Taiwan Strait (28 %), and to the Java Sea through Karimata Strait (22 %). The seasonal variability of this water volume budget is driven by lateral interocean exchanges. Surface interocean exchanges, especially at Luzon Strait, are all driven by monsoon winds that favor winter southwestward flows and summer northeastward surface flows. Exchanges through Luzon Strait deep layers show a stable sandwiched structure with vertically alternating inflows and outflows. Last, differences in flux estimates induced by the use of a high-resolution model vs. a low-resolution model are quantified.

RECEIVING METALS FROM SECONDARY RAW MATERIALS. POWDER OF SILVER

Purpose of research. Powder of silver is one of the most widely used materials in industry. In the free or sintered (compressed) state, it is widely used in medicine as an element of antiseptics, in electronics as the basis of conductive pastes, conductive adhesives and contacts intended for closing and opening electrical circuits, in the production of multilayer ceramic capacitors, etc. Due to its high electrical conductivity, powder of silver is also used as a cathode material in solar cells. In today's conditions, the development of materials for alternative energy sources is quite relevant. Powder of silver can be used as a component of the active mass in chemical current sources. It is known that the characteristics of the active mass are influenced by the properties of the powder, namely, the size and shape of the particles. Materials and methodology. In this work, it was proposed to use boards of radio-electronic equipment as raw materials for the production of powders of silver. The reductant, recovery rate and modes of obtaining finely dispersed powders of silver after processing of secondary raw materials were identified. Results. The influence of the parameters of the reduction of powders of silver, namely, the type of reducing agent and the rate of reduction, was studied. It was established that in the process of forming powders of silver, a developed morphology and space between particles are formed, which increases the surface area, due to which the performance characteristics of various devices, in which powder of silver can be used as a component, will improve. Scientific novelty. Factors that affect the size and shape of powder of silver particles, namely, the type of reducing agent and the rate of reduction, have been established. Conclusions. It was established that the size of particles of silver depends on the speed of recovery. The stronger the reducing agent, the higher the rate of metal reduction, and the larger the particle size. Changing the speed of recovery (slowing down or speeding up) allows you to get particles of silver with the desired size. The indisputable advantage of the method of obtaining powder of silver by reduction is the formation of high-purity metal, which positively affects the properties.

Mechanical properties and damage evolution characteristics of composite rock mass with prefabricated fractures

Mechanical properties and damage evolution characteristics of composite rock mass with prefabricated fractures

A Study on the Results of Risk Analyses Applying the Concept of Rock Mass Stand-Up Time for Underground Mining Sites

Throughout all the countries in the world, including Vietnam, nations with well-established mining industries have undertaken extensive research on the stability of rock masses when constructing underground tunnels in varied geological conditions. The present study aims to provide a comprehensive overview of the risk assessment related to rock masses during the construction of pit lines in mining operations. Consequently, the standing time of unsupported tunnels is assessed based on different values of the strength index and deformation characteristics of the rock mass. The objective was to perform both experimental and theoretical investigations to analyse how the stand-up time of rock masses surrounding a tunnel affects the unsupported span. The analyses were based on considering the rock parameters, including strain modulus; geological strength index; and allowable displacement values, and consideration of hereditary creep properties. By examining tunnels excavated in rock strata, it was concluded that varying geological strength index values resulted in distinct creep behaviour in the surrounding rock masses. Thus, it was reasonable to compute the unsupported span and stand-up time of tunnels. The research revealed that permissible displacements are significantly influenced by the types of rock materials surrounding the tunnel structure. Recognising the significance of time, the authors introduce a more practical interpretation and evaluation of the stability of rock masses, thus enhancing the precision of commonly available models.

Effect of robotic gait training on muscle and bone characteristics in spinal cord transected rats.

Osteoporosis and loss of muscle mass are secondary issues with spinal cord injury. Robotic gait training has provided evidence of increasing bone density and muscle mass, but its effect on bone strength is undetermined. The purpose of this study was to determine the effect of a 6-week robotic locomotion training program on skeletal muscle mass and bone characteristics. Twelve female Sprague-Dawley rats received a mid-thoracic spinal cord transection at 5 days old and at 3 weeks old were assigned to a Control or Trained Group. The Trained Group performed 5-min sessions on the Rat Stepper 5 days a week for 6 weeks with 90% of body weight supported. At the end of the 6 weeks, body mass was obtained and right femurs and four lower extremity muscles were harvested. Femur bone mineral density was measured with DXA and mechanical characteristics of the femur were determined via 3-point bending testing. Independent t-tests, effects sizes and percent differences were computed between the two groups (p < 0.05). The Trained Group had significantly larger normalized femur mass (p = 0.007) and normalized soleus muscle mass (p = 0.033) when compared to the Control Group. There was a medium or large effect size with the Trained Groups' femurs having larger mass, bone mineral density, rupture loads, cortical wall thickness, shaft cross sectional area, soleus mass, normalized gastrocnemius mass, and smaller shaft inner diameters compared to the Control Group. These changes may contribute to decreasing osteoporosis and fracture risk in those with spinal cord injuries.

Analysis of MHD boundary layer flow of a viscous fluid past a stretching sheet employing the Legendre wavelet method

The current work introduces a novel approach to analyse the non-linear Falkner–Skan equation from fluid dynamics by utilising the Legendre wavelet method. In this paper, we relied on the Legendre wavelet to generate a new functional integration matrix and presented a novel approach known as the Legendre wavelet approach (LWA). The primary goal of this study is to provide a unified method via LWA to compute an approximate solution to a non-linear differential equation for a viscous fluid over a stretching sheet. The Legendre wavelet method has been used for the first time to solve the stretching sheet problem. A viscous fluid across a stretching sheet has been explored for its stable laminar magnetohydrodynamic (MHD) flow, transportation of mass and heat characteristics in the context of an intermittent magnetic field. By specifying appropriate non-dimensional parameters, the governing boundary layer equation evolves into a dimension devoid of the Falkner–Skan equation. Using the Legendre wavelet approach, the resulting nonlinear equation modified to an algebraic equation is addressed. With LWA, the undershoots and overshoots for a set of factors are noted. The boundary layer thickness appears to decrease with increasing pressure gradient and magnetic field parameters. The graphical interpretation of the boundary layer flow’s features is done for a range of physical parameter values. To ensure the accuracy of the findings, local skin friction has been tracked and contrasted with other techniques that are already documented in the previous research.

A Case Study for Stability Analysis of a Toppling Bank Slope with Fault Fracture Zones Developed under the Action of Bridge Loads and Reservoir Water

The mountainous areas of Southwest China have the characteristics of valley deep-cutting, a large topographic gradient, complex geological structures, etc. With the development of infrastructure construction in the area, the construction of bridges across valleys has gradually increased, and the phenomenon of slope failure occurs more and more frequently. As the weak interlayer, the fault fracture zones have a significant influence on the geological structure and stability of slopes, while the complexity of the mechanism of the deformation and failure of slopes increases with the combination of the development of the fracture zones and toppling deformation. This paper took the toppling bank slope of bridge foundations developed with fault fracture zones in Lancang River as the research object. Through an on-site field survey and geological survey technologies, it identified the distribution range of the fracture zones on the bank slope and determined the characteristics of the rock mass in the fracture zones. A stability evaluation model for the bank slope of the bridge foundations was established using the limit equilibrium method and discrete element method. Based on the two-dimensional limit equilibrium analysis, the potential failure modes of the bank slope were explored, and the stability of the bank slope under bridge loads was calculated. Through the three-dimensional geological model of the bank slope, including the fracture zones and toppling bodies, the three-dimensional discrete element numerical simulation method was adopted to simulate and calculate the deformation and failure process of the bank slope under different bridge loads and working conditions. According to the calculation results, the influence of bridge loads and reservoir water on the stability of the bank slope was analyzed from the perspectives of displacement, plastic zone, stability coefficient, and other factors. The formation process of the plastic zone and the development of the sliding surface were revealed, the incentive mechanism of bridge loads and reservoir water on the deformation and failure of the bank slope was analyzed, and the influence of fault fracture zones on the stability of the bank slope and the development of toppling deformation was determined. The results indicate that the fault fracture zones are important geological structures that affect the deformation and failure of the bank slope as a weak interlayer. Under the influence of bridge loads and reservoir water, the stability of the bank slope is affected by the quality of the rock mass and the development of the fault fracture zones, resulting in the unmet need for safety requirements and maybe leading to instability. Based on the calculation results of the stability evaluation prediction model for the bridge foundation bank slope and the engineering geological conditions, the bridge scheme has been selected.

Rock Mass Structure Classification of Caves Based on the 3D Rock Block Index

In large-scale water conservancy and hydropower projects, complex rock structures are considered to be the main factor controlling the stability of hydraulic structures. The classification of rock mass structure plays an important role in the safety of all kinds of large buildings, especially underground engineering buildings. As a quantitative classification index of rock mass, the rock block index is very common in the classification of borehole and dam foundation rock mass structures. However, there are few studies on the classification of underground engineering rock masses. Moreover, their classification criteria have disadvantages in spatial dimension. Therefore, this paper takes the long exploratory cave CPD1 in the water transmission and power generation system of the Qingtian pumped storage power station in Zhejiang Province as the research object and launches a study on the structural classification of the rock mass of a flat cave based on the 3D rock block index. According to the group distribution of joints, the sections are statistically homogeneous. Additionally, the Monte Carlo method is used to carry out random simulations to generate a three-dimensional joint network model. The virtual survey lines are arranged along the center of the shape of the three different orthogonal planes of the 3D joint network model to represent the boreholes, and the RBI values of the virtual survey lines on each orthogonal plane are counted to classify the rock mass structure of the flat cave in a refined manner using the rock block index of the rock mass in 3D. The above method realizes the application of the 3D rock block index in underground engineering and overcomes the limitations of traditional rock mass classification methods in terms of classification index and dimension. The results show that: (1) Three-dimensional joint network simulations built on statistical and probabilistic foundations can visualize the structure of the rock mass and more accurately reflect the structural characteristics of the actual rock mass. (2) Based on the 3D rock block index, the rock mass structure of the long-tunnel CPD1 is classified, from that of a continuous structure to a blocky structure, corresponding to the integrity of the rock mass from complete to relatively complete. The classification results are consistent with the evaluation results of horizontal tunnel seismic wave geophysical exploration. (3) Based on the 3D joint network model, it is reasonable and feasible to use the 3D rock block index as a quantitative evaluation index to determine the structure type of flat cave rock masses. The above method is helpful and significant in the classification of underground engineering rock mass structures.

Loss of PA28γ exacerbates imbalanced differentiation of bone marrow stromal cells during bone formation and bone healing in mice.

Proteasome activator subunit 3 (PA28γ) is a member of the proteasome activator family, which mainly regulates the degradation and stability of proteins. Studies have shown that it plays crucial roles in lipid formation, stemness maintenance, and blood vessel formation. However, few studies have clarified the association between PA28γ and bone diseases. Herein, we identified PA28γ as a previously unknown regulator of bone homeostasis that coordinates bone formation and lipid accumulation. PA28γ-knockout mice presented with the characteristics of low bone mass and accumulation of lipids. Suppressed expression of PA28γ restrained the osteogenic differentiation and enhanced the adipogenic differentiation of bone marrow stromal cells (BMSCs). Overexpression of PA28γ promoted osteogenic differentiation and inhibited adipogenic differentiation of BMSCs. Mechanistically, PA28γ interacted with Wnt5α, and the two interactors appeared to be positively correlated. PA28γ mainly activated the downstream Wnt/β-catenin signaling pathway, which affects BMSCs differentiation homeostasis. Deletion of Wnt5α significantly delayed the promotion of osteogenic differentiation and partially alleviated the inhibitory effect of adipogenic differentiation of BMSCs in the PA28γ-overexpressing group. Furthermore, we demonstrated that PA28γ-knockout mice had an inhibited rate of bone healing in a drill-hole femoral bone defect model in vivo. Therefore, our results confirm the effects of PA28γ on bone formation and bone defect repair, indicating that PA28γ mainly interacts with Wnt5α to activate the Wnt/β-catenin signaling pathway regulating BMSCs differentiation homeostasis. Our results reveal the function of PA28γ in bone diseases and provide a new theoretical basis for expanding the treatment of bone diseases.

Novel robot arm concept for lightweighting high-performance machinery

Abstract To improve the efficiency of robots, a novel sustainable design of a robotic arm is proposed that can address the thermal, vibration, energy usage and dynamic stiffness issues. The proposed design utilises easy-to-produce carbon fibre tubes including some that are commercially available, for the robot link instead of traditional materials, which can be heavy and carbon intensive. The design involves arranging several carbon fibre reinforced polymer (CFRP) tubes in a specific array inside an epoxy resin substrate. Based on this design, a Finite Element Analysis (FEA) was implemented demonstrating the relatively low mass and high stiffness characteristics. Design optimisation was then performed using custom generated MATLAB® code to reduce the computation time. The proposed design for a one-meter-long robot link with a diameter of 108 mm offers a stiffness of 0.75 N/μm. A structural steel link, with the same stiffness, is 33 % heavier than the concept design. The design maintains thermal stability with about a third of the thermal deformation seen in structural steel.

Comparative Study of Rock Mass Classification Systems: A Case Study of Nagdhunga-Naubisea Road Tunnel

Ground classification systems have been widely used to characterize the soil or rock mass for the analysis and design of underground structures. Deformation characteristics of rock mass around the underground excavation boundary varies according to types of rock and their properties, in situ stress condition and types of support used. Broadly used classification systems for underground structures are Rock Mass Rating (RMR) and Rock Quality Index (Q- Systems) but in-case of the Nagdhunga-Naubisea road tunnel Nippon Expressway Company Limited used NEXCO-System. Literally, the NEXCO classification is based on the velocity of elastic wave, geological condition, boring core condition, competence factor, stability of tunnel face and convergence. However, in-case of Nagdhunga-Naubisea road tunnel, grade point is computed using the similar parameters that are used in RMR- System and Q-System. This research focuses about comparison between ground classification from RMR, Q-system and NEXCO system. The geological descriptions obtained from project office at chainages (0+497 to 0+502), (0+508 to 0+513), (0+581.8 to 0+587.8) and (0+584.2 to 0+590.2) were used to correlate the relationship between RMR, Q-system and NEXCO system of rock mass classification systems. Results showed that from RMR, the ground classification is “poor” at all the chainages whereas from Q-system is “very poor” at chainage (0+508 to 0+513) and “poor” at other chainages. Similarly, from NEXCO- system it was found that “DII” at chainages (0+497 to 0+502) and (0+508 to 0+513) and CII for chainages (0+581.8 to 0+587.8) and (0+584.2 to 0+590.2). These results revealed that the ground classification from NEXCO as DII is similar to poor from RMR and poor or very poor from Q system where as CII from NEXCO is similar to poor from both RMR and Q system.