Stone Particle Research Articles

Direct in-scope suction: an in vitro evaluation of a single use flexible ureteroscope with integrated suction capability.

To evaluate the stone clearance rate and limitations of a novel integrated suction capability within a single-use flexible ureteroscope according to stone particle size. Varying sized stone particles were created using a stone phantom (Begostone Plus, Bego ©, Lincoln, RI, USA). Particle size ranged as follows: 63-125µm, 125-250µm, 250-500µm, 500µm- 1mm and 1-2mm. These were mixed with Normal saline (0.9%) to mimic in vivo conditions. The suction enabled single-use flexible ureteroscope (Pusen, Zhuhai, China) was used to aspirate stone fragments in three trials. Firstly, aspiration of 5g of each dust range was attempted. Secondly, a direct comparison of the integrated suction to a manual syringe technique was applied to 1g of each size range. Finally, aspiration was applied to 5g of a heterogenous 1:1:1:1:1 mixture. Endoscopic clearance rate (g/min) and number of blockages were recorded. Each challenge was repeated three times. The integrated suction cleared 100% of dust < 250µm. Endoscopic clearance rates were significantly faster than manual aspiration (3.01g/min versus 0.41g/min) for dust between 125 and 250µm (p = 0.008). Complete endoscopic clearance by 180s (without encountering test limiting blockages) was unsuccessful for particles > 250µm. Clearance rates were greatly limited by stone particle size heterogeneity above 250µm, to 0.09g/min. This technology works better in vitro than previously DISS evaluated methods when challenged by stone dust < 250µm. However, this adaptation is significantly challenged in the presence of stone dust particles > 250µm.

What is the definition of stone dust and how does it compare with clinically insignificant residual fragments? A comprehensive review.

During endoscopic stone surgery, Holmium:YAG(Ho:YAG) and Thulium Fiber Laser(TFL) technologies allow to pulverize urinary stones into fine particles, ie DUST. Yet, currently there is no consensus on the exact definition of DUST. This review aimed to define stone DUST and Clinically Insignificant Residual Fragments(CIRF). Embase, MEDLINE(PubMed) and Cochrane databases were searched for both in vitro and in vivo articles relating to DUST and CIRF definitions, in November 2023, using keyword combinations: "dust", "stones", "urinary calculi", "urolithiasis", "residual fragments", "dusting", "fragments", "lasers" and "clinical insignificant residual fragments". DUST relates to the fine pulverization of urinary stones, defined in vitro as particles spontaneously floating with a sedimentation duration ≥ 2sec and suited for aspiration through a 3.6Fr-working channel(WC) of a flexible ureteroscope(FURS). Generally, an upper size limit of 250µm seems to agree with the definition of DUST. Ho:YAG with and without "Moses Technology", TFL and the recent pulsed-Thulium:YAG (pTm:YAG) can produce DUST, but no perioperative technology can currently measure DUST size. The TFL and pTm:YAG achieve better dusting compared to Ho:YAG. CIRF relates to residual fragments(RF) that are not associated with imminent stone-related events: loin pain, acute renal colic, medical or interventional retreatment. CIRF size definition has decreased from older studies based on Shock Wave Lithotripsy(SWL)(≤ 4mm) to more recent studies based on FURS(≤ 2mm) and Percutaneous Nephrolithotomy(PCNL)(≤ 4mm). RF 2mm are associated with lower stone recurrence, regrowth and clinical events rates. While CIRF should be evaluated postoperatively using Non-Contrast Computed Tomography(NCCT), there is no consensus on the best diagnostic modality to assess the presence and quantity of DUST. DUST and CIRF refer to independent entities. DUST is defined in vitro by a stone particle size criteria of 250µm, translating clinically as particles able to be fully aspirated through a 3.6Fr-WC without blockage. CIRF relates to ≤ 2 RF on postoperative NCCT.

Pulsed thulium:YAG laser—ready to dust all urinary stone composition types? Results from a PEARLS analysis

PurposeTo evaluate whether stone dust can be obtained from all prevailing stone composition types using the novel pulsed thulium:YAG (p-Tm:YAG), including analysis of stone particle size after lithotripsy.MethodsHuman urinary stones of 7 different compositions were subjected to in vitro lithotripsy using a p-Tm:YAG laser with 270 µm silica core fibers (Thulio®, Dornier MedTech GmbH®, Wessling, Germany). A cumulative energy of 1000 J was applied to each stone using one of three laser settings: 0.1 J × 100 Hz, 0.4 J × 25 Hz and 2.0 J × 5 Hz (average power 10 W). After lithotripsy, larger remnant fragments were separated from stone dust using a previously described method depending on the floating ability of dust particles. Fragments and dust samples were then passed through laboratory sieves to evaluate stone particle count according to a semiquantitative analysis relying on a previous definition of stone dust (i.e., stone particles ≤ 250 µm).ResultsThe p-Tm:YAG laser was able to produce stone dust from lithotripsy up to measured smallest mesh size of 63 µm in all seven stone composition types. Notably, all dust samples from all seven stone types and with all three laser settings had high counts of particles in the size range agreeing with the definition stone dust, i.e., ≤ 250 µm.ConclusionThis is the first study in the literature proving the p-Tm:YAG laser capable of dusting all prevailing human urinary stone compositions, with production of dust particles ≤ 250 µm. These findings are pivotal for the broader future implementation of the p-Tm:YAG in clinical routine.

Role of different mechanisms in pro-inflammatory responses triggered by traffic-derived particulate matter in human bronchiolar epithelial cells

BackgroundTraffic-derived particles are important contributors to the adverse health effects of ambient particulate matter (PM). In Nordic countries, mineral particles from road pavement and diesel exhaust particles (DEP) are important constituents of traffic-derived PM. In the present study we compared the pro-inflammatory responses of mineral particles and DEP to PM from two road tunnels, and examined the mechanisms involved.MethodsThe pro-inflammatory potential of 100 µg/mL coarse (PM10-2.5), fine (PM2.5-0.18) and ultrafine PM (PM0.18) sampled in two road tunnels paved with different stone materials was assessed in human bronchial epithelial cells (HBEC3-KT), and compared to DEP and particles derived from the respective stone materials. Release of pro-inflammatory cytokines (CXCL8, IL-1α, IL-1β) was measured by ELISA, while the expression of genes related to inflammation (COX2, CXCL8, IL-1α, IL-1β, TNF-α), redox responses (HO-1) and metabolism (CYP1A1, CYP1B1, PAI-2) was determined by qPCR. The roles of the aryl hydrocarbon receptor (AhR) and reactive oxygen species (ROS) were examined by treatment with the AhR-inhibitor CH223191 and the anti-oxidant N-acetyl cysteine (NAC).ResultsRoad tunnel PM caused time-dependent increases in expression of CXCL8, COX2, IL-1α, IL-1β, TNF-α, COX2, PAI-2, CYP1A1, CYP1B1 and HO-1, with fine PM as more potent than coarse PM at early time-points. The stone particle samples and DEP induced lower cytokine release than all size-fractionated PM samples for one tunnel, and versus fine PM for the other tunnel. CH223191 partially reduced release and expression of IL-1α and CXCL8, and expression of COX2, for fine and coarse PM, depending on tunnel, response and time-point. Whereas expression of CYP1A1 was markedly reduced by CH223191, HO-1 expression was not affected. NAC reduced the release and expression of IL-1α and CXCL8, and COX2 expression, but augmented expression of CYP1A1 and HO-1.ConclusionsThe results indicate that the pro-inflammatory responses of road tunnel PM in HBEC3-KT cells are not attributed to the mineral particles or DEP alone. The pro-inflammatory responses seem to involve AhR-dependent mechanisms, suggesting a role for organic constituents. ROS-mediated mechanisms were also involved, probably through AhR-independent pathways. DEP may be a contributor to the AhR-dependent responses, although other sources may be of importance.

Study on hard rock particle size division based on Mars rover traction performance

To simplify the dynamic solution of the contact between the rigid wheel of Mars rover and the spherical hard stone on the mixed terrain, a model for hard stone particle size division based on the traction performance of Mars rover is proposed. On the mixed terrain of hard rock and soft soil, the movement of hard rock will affect the traction performance of the rigid wheels of Mars rover. According to the different effects of the hard stones on the traction performance of rigid wheels, stones are divided into three types. The static sinkage of rigid wheels is calculated according to the Bekker bearing model, and the calculation formula of sliding sinkage of rigid wheels and hard stone sinkage is proposed. The type of hard stones is determined by comparing the sinkage of hard stones and rigid wheels. Finally, three kinds of hard stones with slip ratios of 0.2, 0.5, and 0.7 were substituted into the single wheel simulation platform and the soil trough experiment platform for simulation and experiment. The results show that on mixed terrain, the error of simulation and experimental results of fixed hard stones under three slip rates is below 5.4%, the error of drawbar pull in simulation and experimental results of movable hard stones is above 126%, and the error of simulation and experimental results of scattered small hard stones is below 2%, which verifies the effectiveness of the hard stone particle size division model.

Effects of particle size on quality characteristics of stone-milled whole wheat flour.

Whole wheat flour (WWF) prepared by the direct crushing method preserves all the components of the whole wheat grain. WWF with different particle sizes (180, 150, 125, 106, and 96 μm) was obtained by combining stone milling and particle size sieving technology. The effects of particle size on the proximate composition, farinograph, pasting, thermal, and functional properties, starch microstructure, and Fourier-transform infrared (FTIR) spectroscopy of stone-milled WWF were investigated. The smaller the particle size of WWF, the higher the damaged starch content. The water absorption, degree of softening, pasting temperature, solubility, and syneresis of WWF increased steadily as the particle size decreased, whereas the peak viscosity, final viscosity, swelling power, water holding capacity, and enthalpy of gelatinization decreased. The scanning electron microscope micrographs revealed that the larger the particle size of WWF, the denser the distribution of starch granules. The β-sheet and β-turn contents of WWF with particle size 180 μm were the highest, reaching up to 33.85% and 39.79%, respectively. The particle size exerted influence on the quality characteristics of stone-milled WWF, and the overall properties of WWF were better at medium particle size. © 2023 Society of Chemical Industry.

The importance of mineralogical composition for the cytotoxic and pro-inflammatory effects of mineral dust

BackgroundRespirable mineral particles represent a potential health hazard in occupational settings and ambient air. Previous studies show that mineral particles may induce cytotoxicity and inflammatory reactions in vitro and in vivo and that the potency varies between samples of different composition. However, the reason for these differences is largely unknown and the impact of mineralogical composition on the biological effects of mineral dust remains to be determined.MethodsWe have assessed the cytotoxic and pro-inflammatory effects of ten mineral particle samples of different composition in human bronchial epithelial cells (HBEC3-KT) and THP-1-derived macrophages, as well as their membranolytic properties in erythrocytes. Moreover, the results were compiled with the results of recently published experiments on the effects of stone particle exposure and analysed using linear regression models to elucidate which mineral components contribute most to the toxicity of mineral dust.ResultsWhile all mineral particle samples were more cytotoxic to HBEC3-KT cells than THP-1 macrophages, biotite and quartz were among the most cytotoxic in both cell models. In HBEC3-KT cells, biotite and quartz also appeared to be the most potent inducers of pro-inflammatory cytokines, while the quartz, Ca-feldspar, Na-feldspar and biotite samples were the most potent in THP-1 macrophages. All particle samples except quartz induced low levels of membranolysis. The regression analyses revealed associations between particle bioactivity and the content of quartz, muscovite, plagioclase, biotite, anorthite, albite, microcline, calcite, chlorite, orthopyroxene, actinolite and epidote, depending on the cell model and endpoint. However, muscovite was the only mineral consistently associated with increased cytotoxicity and cytokine release in both cell models.ConclusionsThe present study provides further evidence that mineral particles may induce cytotoxicity and inflammation in cells of the human airways and that particle samples of different mineralogical composition differ in potency. The results show that quartz, while being among the most potent samples, does not fully predict the toxicity of mineral dust, highlighting the importance of other particle constituents. Moreover, the results indicate that the phyllosilicates muscovite and biotite may be more potent than other minerals assessed in the study, suggesting that this group of sheet-like minerals may warrant further attention.

The behavior of heavy metal release from sulfide waste rock under microbial action and different environmental factors.

The dissolution of heavy metals from the waste rock is controlled by many factors. Herein, we investigated the release behavior of iron (Fe), chromium (Cr), copper (Cu), and zinc (Zn) from sulfide waste rock under the actions of microorganisms and different environmental factors (solution pH value, particle size of waste rock, temperature, Fe3+ concentration). The release quantity of heavy metals was negatively correlated with pH and particle size and positively correlated with ambient temperature and Fe3+ concentration. Under the experimental conditions of pH value of 3.0, temperature of 35°C, and waste stone particle size of less than 0.075 mm,, the release quantity of Fe, Cr, Cu, and Zn reached 3680, 18.32, 132.20, 26.60 mg·kg-1 after 20 days of leaching, respectively. Rising the temperature to 45 °C, Fe, Cr, Cu, and Zn release quantities increased to 89.30, 5.81, 105.08, and 28.00 mg·kg-1. Six hundred milligrams per liter Fe3+ increased the release of heavy metals considerably (2.63-65.48 folds). The presence of microorganisms can significantly facilitate the release of heavy metals. Compared to the control group, the release quantities of Fe, Cr, Cu, and Zn increased 4.29, 3.17, 1.54, and 2.39 times, respectively. In addition, the waste rock under microbial action was more seriously corroded than that under chemical factors. The release behavior of these four heavy metals was consistent with the interfacial chemical reaction control model, indicating that the reactions mainly occurred on the surface of the waste rock. This study provides an essential reference for the study of heavy metal leaching behavior.

The pro-inflammatory effects of combined exposure to diesel exhaust particles and mineral particles in human bronchial epithelial cells

BackgroundPeople are exposed to ambient particulate matter (PM) from multiple sources simultaneously in both environmental and occupational settings. However, combinatory effects of particles from different sources have received little attention in experimental studies. In the present study, the pro-inflammatory effects of combined exposure to diesel exhaust particles (DEP) and mineral particles, two common PM constituents, were explored in human lung epithelial cells.MethodsParticle-induced secretion of pro-inflammatory cytokines (CXCL8 and IL-1β) and changes in expression of genes related to inflammation (CXCL8, IL-1α, IL-1β and COX-2), redox responses (HO-1) and xenobiotic metabolism (CYP1A1 and CYP1B1) were assessed in human bronchial epithelial cells (HBEC3-KT) after combined exposure to different samples of DEP and mineral particles. Combined exposure was also conducted using lipophilic organic extracts of DEP to assess the contribution of soluble organic chemicals. Moreover, the role of the aryl hydrocarbon receptor (AhR) pathway was assessed using an AhR-specific inhibitor (CH223191).ResultsCombined exposure to DEP and mineral particles induced increases in pro-inflammatory cytokines and expression of genes related to inflammation and redox responses in HBEC3-KT cells that were greater than either particle sample alone. Moreover, robust increases in the expression of CYP1A1 and CYP1B1 were observed. The effects were most pronounced after combined exposure to α-quartz and DEP from an older fossil diesel, but enhanced responses were also observed using DEP generated from a modern biodiesel blend and several stone particle samples of mixed mineral composition. Moreover, the effect of combined exposure on cytokine secretion could also be induced by lipophilic organic extracts of DEP. Pre-incubation with an AhR-specific inhibitor reduced the particle-induced cytokine responses, suggesting that the effects were at least partially dependent on AhR.ConclusionsExposure to DEP and mineral particles in combination induces enhanced pro-inflammatory responses in human bronchial epithelial cells compared with exposure to the individual particle samples. The effects are partly mediated through an AhR-dependent pathway and lipophilic organic chemicals in DEP appear to play a central role. These possible combinatory effects between different sources and components of PM warrant further attention and should also be considered when assessing measures to reduce PM-induced health effects.

Quantitative analysis of geometric characteristics of crushed-stone-reinforced polymer composite microstructures

The stiffness and structural costs of a polymer can be effectively improved and reduced, respectively, by adding crushed stone aggregates. Therefore, it is necessary to study the effect of crushed stones on polymer composites. Scanning electron microscopy (SEM) and digital image processing analysis (DIPA) technology were adopted to study the micromorphologies of polymers and crushed-stone-reinforced polymer (SRP) composites with medium and high densities. A method for defining and determining the interface transition zone (ITZ) between the polymer and crushed stone was proposed. The distribution characteristics of the cell structure and ITZ in the SRP were statistically analyzed, and the influence of the crushed stone particle spacing on the polymer microstructure was explored. The results show that two types of ITZs are present in the SRP: low density (i.e., an ITZ density lower than that of the matrix) and high density (i.e., an ITZ density higher than that of the matrix). Furthermore, the relative content of the low-density ITZ decreases under the increase in SRP polymer density. The ITZ thickness in the SRP is generally below 1500 μm. Under an identical polymer density, the ITZ thickness increases under an increase in particle spacing; under an identical particle spacing, the ITZ thickness increases with an increase in polymer density. This provides a theoretical basis for exploring the strength meso-mechanisms of SRPs and establishing meso-level finite element models.

Modelling of yields in torrefaction of olive stones using artificial intelligence coupled with kriging interpolation

A predictive model is developed using an artificial neural network (ANN) to calculate the solid-liquid, and gas yields (wt %) from the torrefaction of olives stones, based on the material and process parameters. These parameters are average olive stone particle size, reaction temperature and reaction time. Ordinary Kriging interpolation is coupled with ANN to improve the experimental data resolution by increasing the data points used in building the ANN models. This coupling improved the ANN prediction accuracy (R2) by 11.1%, 13.5%, and 1.0% in training and 27.3%, 8.5%, and 14.8% in validation of the solid, liquid and gas yields, respectively. Also, the mean absolute deviations of the models significantly improved after the coupling. The prediction profiles show a linear relationship between the solid and liquid yields and a nonlinear relation for the gas yields in terms of the material and process parameters. Average olive stone particle size showed the highest effect on the yields due to the improvement in heat transfer with the exposed surface area of the olive stones leading to a faster reaction rate.

Influence of stone powder content and particle size on the strength of cement-treated clay

Particle size of additive geomaterials could affect the cement–clay reaction, thereby reducing strength. The effects of five particle sizes (A, B, C, D and E: >75, 40–75, 20–40, <20 and < 1–106 µm, respectively) of waste granite powder in cement-treated clay mixed composites were investigated. The effects on the liquid limit, unconfined compressive strength (UCS) and microstructural characteristics were investigated. The particle size influenced the UCS in the order of D > A > C > B, and D exhibited higher UCS than the control sample. The increase in the UCS was due to the increased surface area and pozzolanic reactivity of stone powder D. A reduction in the UCS of cement-treated clay–stone powder E composites occurred as compared to the control sample with a 30% stone powder addition, and equal or improved strength was observed with 50% and 70% additions. Owing to the UCS increment derived from stone powder, we could reduce 28.6% of the cement.

Structural characteristics of soil-rock mixtures based on electrochemical impedance spectroscopy

Geotechnical problems in extremely complex environments have become increasingly prominent, which raises the need to explore more efficient solutions. Multidisciplinary approaches show a new perspective to deal with these problems. In this study, the electrochemical impedance spectroscopy (EIS) was introduced to illustrate the structural characteristics of soil-rock mixtures (SRM), aiming at deducing the relationship between physical property indices such as the mass ratio indices (e.g., water content, soil-rock ratio, and stone particle size) and volume ratio indices (e.g., porosity and saturation) and equivalent circuit at the macro and micro levels. A three-level equivalent circuit corresponding with the physical characteristic of SRM was established to describe the cementation state. It shows that the degree of cementation of SRM increases with increasing water content, rock content, and median size of block stone; meanwhile, the real impedance coefficient of the non-cemented part is lower than that of the cemented part. The corresponding relationship between the imaginary impedance and the specific gravity has segmental characteristics. The density first increases and then decreases with the increase of water content; the water content and saturation threshold are 16% and 80 ± 2%, respectively. Moreover, the saturation (Sr and n∙Sr) decreases with the increase in the real impedance coefficient. In addition, the characteristics of the propagation mode and interfacial contact characteristics of the charged material inside SRM were examined, and the macro and micro mapping of the cementation state of SRM and the basic mass transfer mode (i.e., migration, diffusion, and convection) were obtained. The mapping relationship proposed in this study reflects the micro-scale cementation characteristics and the macro-scale physical characteristics of the SRM system, which provides new insight into the multi-scale research of SRM.

Respirable stone particles differ in their ability to induce cytotoxicity and pro-inflammatory responses in cell models of the human airways

BackgroundRespirable stone- and mineral particles may be a major constituent in occupational and ambient air pollution and represent a possible health hazard. However, with exception of quartz and asbestos, little is known about the toxic properties of mineral particles. In the present study, the pro-inflammatory and cytotoxic responses to six stone particle samples of different composition and with diameter below 10 μm were assessed in human bronchial epithelial cells (HBEC3-KT), THP-1 macrophages and a HBEC3-KT/THP-1 co-culture. Moreover, particle-induced lysis of human erythrocytes was assessed to determine the ability of the particles to lyse biological membranes. Finally, the role of the NLRP3 inflammasome was assessed using a NLRP3-specific inhibitor and detection of ASC oligomers and cleaved caspase-1 and IL-1β. A reference sample of pure α-quartz was included for comparison.ResultsSeveral stone particle samples induced a concentration-dependent increase in cytotoxicity and secretion of the pro-inflammatory cytokines CXCL8, IL-1α, IL-1β and TNFα. In HBEC3-KT, quartzite and anorthosite were the most cytotoxic stone particle samples and induced the highest levels of cytokines. Quartzite and anorthosite were also the most cytotoxic samples in THP-1 macrophages, while anorthosite and hornfels induced the highest cytokine responses. In comparison, few significant differences between particle samples were detected in the co-culture. Adjusting responses for differences in surface area concentrations did not fully account for the differences between particle samples. Moreover, the stone particles had low hemolytic potential, indicating that the effects were not driven by membrane lysis. Pre-incubation with a NLRP3-specific inhibitor reduced stone particle-induced cytokine responses in THP-1 macrophages, but not in HBEC3-KT cells, suggesting that the effects are mediated through different mechanisms in epithelial cells and macrophages. Particle exposure also induced an increase in ASC oligomers and cleaved caspase-1 and IL-1β in THP-1 macrophages, confirming the involvement of the NLRP3 inflammasome.ConclusionsThe present study indicates that stone particles induce cytotoxicity and pro-inflammatory responses in human bronchial epithelial cells and macrophages, acting through NLRP3-independent and -dependent mechanisms, respectively. Moreover, some particle samples induced cytotoxicity and cytokine release to a similar or greater extent than α-quartz. Thus, these minerals warrant further attention in future research.

Novel Approach for Reinforcement the Extraction of ECG Signal for Twin Fetuses Based on Modified BSS

One of the most used traditional method to measure heart conductivity of fetal is the fetal Electrocardiography (FECG). Many indicators related to the health of fetal can be determined depending on FECG since fetal heart rate (FHR) is obtained from the components of FECG signal. Recording fetal ECG in a clinic forms a problem due to the interferences of other signals which corrupt the ECG signal. Another problem happen as a result to the location of the used electrodes for recording ECG since these electrodes are placed on the mother abdomen. The obtained abdominal ECG signal also contain different types of interferences. The maternal ECG represents the first big interference source with the FECG signal. Breathing, the activity of mother's muscle, electrode contact with the mother's skin, power line interference and thermal noise, all of them represent a possible noise source. In case of extraction ECG signal for twin gestation, clear FECG for every single fetal would be more difficult because in addition to the all mentioned source of interferences and noise, both fetuses may share the same morphology and FHR. Close monitoring to the heart of twin is required for early diagnose of congenial problems which infect heart. In this study a novel approach has been made by combining conventional Stone BSS and particle swarm optimization (PSO) to produce (MSBSS). The obtained results are compared with other two BSS algorithms (EFICA and JADE) in addition to the obtained results using conventional Stone BSS. MSBSS method has revealed better performance comparing with the other BSS techniques including original Stone BSS.

Analysis of the pick-up of crushed stone particles in a horizontal pipeline

The feeder is a key component of a pneumatic conveying system, and it is the largest component that causes pressure loss. In this paper, a negative-pressure auto-feeding system was designed. Using the orthogonal design method, the effects of the airflow velocity, particle size, and feeding mass on the pick-up mass of an auto-feeding system were investigated experimentally. Based on a range analysis, the serial number for the importance of each factor to the pick-up mass was determined. The pressure in the horizontal pipeline was obtained from pressure transmitters, and the effects of the airflow velocity, particle size, and feeding mass on the airflow pressure of the auto-feeding system were investigated. By normalizing the maximum pressure signal and the material pick-up masses, the relationship between the flow field pressure signal and the crushed stone particle pick-up mass was obtained.

Meteors with extreme beginning heights from observations with high-sensitivity super-isocon TV systems

ABSTRACT Meteors with extremely high altitudes are considered. Parameters of seven meteors having anomalous beginning heights recorded with highly sensitive super-Isocon TV systems are presented. One 1993 Perseid meteor, one 2001 sporadic meteor and five meteors from the 2002 Leonid storm had beginning heights in the range 135–145 km. The sporadic meteor is used to demonstrate the methods of data processing and observation precision results. The original TV meteor images, photometric calibration curves and meteor light curve are shown. Light curves are shown for the Leonid shower meteors as well. Based on the sporadic meteor and the 2002 Leonid shower meteor data, mass-loss curves were calculated as functions of height and time: the maximum rates of mass loss were 0.14 and 0.20 g s−1, respectively. Using the classic equation for partially isothermal stone particle heating, the detected beginning heights of most meteors considered (136–135 km) are shown to possibly be related to blowing the molten layer off from a meteoroid surface and most segments of the light curves (below 124 km) show intensive evaporation. For some Leonid meteors, appearing higher than 145–140 km, energy exchange of atmosphere molecules and atoms with the ‘cold’ meteoroid surface can also be assumed. Another possible explanation lies in the low melting temperature of 1500–1600 K for Leonid meteors.

Manufacturing process and mechanical properties of a novel acrylonitrile butadiene styrene-based composite, with recycled natural granite micro-particles

Manufacture and characterization of a novel, environmentally friendly stone composite based on acrylonitrile butadiene styrene (ABS) and recycled natural granite stone particles is introduced. The proposed composite can be considered as a byproduct of natural stone processing, and potentially lead to a solution to the associated waste management problem. Results indicated that the composite’s tensile strength and fracture property generally deteriorated with increasing the stone particle content, especially beyond 50%. Stiffness and thermal conductivity, however, continually increased with the addition of the granite powder, which would suggest multi-functional applications of this material.

Augmented heat and mass transfer effect on performance of a solar still using porous absorber: Experimental investigation and exergetic analysis

In this paper, an experimental study is performed to investigate the influence of heat and mass transfer enhancement on the solar still thermodynamic performance by using porous absorber. This study used two identical solar stills with the basin area of 1 m2: one is conventional and the other has a layer of fine basalt stones in the base of the still as a porous absorber with different particle size (1 cm, 1.5 cm and 2 cm). The experimental results showed that the average Nusselt and Sherwood numbers inside the solar still cavity by using porous bed with different porosity based on stone particle size were enhanced by about 115% and 51.95% respectively. Also, The exergy efficiency of the solar still with the 1 cm, 1.5 cm and 2 cm fine stone particle size was enhanced by about 65%, 104.4% and 123% respectively compared to solar still without stones. In addition, the empirical correlations to estimate the Nusselt and Sherwood numbers inside the solar still cavity were obtained. The agreement between these correlations and experimental results was fairly good.

Test Research on the Meso-Fabric Properties of Undisturbed Moraine Soil on the West Side of Yulong Snow Mountain

Meso-fabric of gravel particles is not only a reflection of the unique sedimentary history, but also directly affects the geotechnical properties of moraine soil. However, there are few researches on it so far in geotechnical engineering field, due to the difficulty of obtaining undisturbed moraine soil sample. To change this situation, we succeeded in getting undisturbed moraine soil samples from the west side of the Yulong Snow Mountain with the delicate manual cutting work. We scaned the 6 pieces of moraine soil samples by CT instrument and obtained the real meso-fabric images of internal moraine soil for the first time. After CT images binarization and denoising processing with the help of Matlab, section fabric indexes of stone area ratio, grain orientation and particle shape of moraine soil gravel particles were described with conventional statistical methods. The results show that the differences between vertical sections are little, but the differences between vertical sections and horizontal sections are much more obvious.