Accumulation Process Research Articles

LAS-on-edge: A real-time laser absorption spectroscopic water vapor sensor on edge computing platforms

Real-time and in situ water vapor (H2O) sensors are increasingly demanded to indicate thermochemical parameters of energy systems. As an accurate, fast and non-intrusive sensing technology, laser absorption spectroscopy (LAS) enables simultaneous measurement of gas concentration and temperature. Due to the complex spectral computation, real-time and rapid LAS signal processing are still challenging. Most state-of-the-art LAS sensors utilize high-level computing units to post-process laser measurements in real time, hindering their portable deployment in harsh industrial environments. To address the above challenge, we developed an online LAS gas sensor on edging computing platforms, named as LAS-on-Edge. The developed sensor achieves an online monitoring rate up to 62.5 Hz by deploying a spectral-informed neural network on an embedded device. Simultaneously, it reserves the raw kilo-Hz measurements offline for underlying dynamics understanding. The LAS-on-Edge sensor’s compactness also enables its flexible and in situ integration. The sensor is firstly used to monitor a slow mist diffusion and accumulation process, exhibiting a high measurement accuracy with low spectra recovery residuals below 0.01. It is further applied to online monitor the H2O concentration and temperature variation during a lab-scale propane combustion process. It demonstrates a minimal temperature deviation of 1.86 % compared to the thermocouple reference in the flame. The sensor also successfully detects the fundamental flame pulsation at 5.65 Hz as well as high-frequency pulsations exceeding 200 Hz, thereby effectively reveals underlying flame dynamic behaviors.

Local weather phenomenon Galerna influences daily radon concentrations in northern Iberian Peninsula

One of the main factors that affect urban air quality is meteorology. The objective of this study is to understand and characterise the influence that “Galerna” (GL) (an abrupt westerly change over the northern coast of Spain) has on the daily variability of the air quality over Bilbao city (northern Spain). A total of 46 one-day periods from 2009 to 2019 during which GL have been analysed. Radon observations at the Bilbao city radiological station were used because radon is a suitable atmospheric tracer by which to assess and characterise air quality dynamics. The cluster analysis of these periods revealed that increases in radon concentrations, mainly in the afternoon, are associated with the occurrence of GL, but that, this increase in the daily variability of radon concentrations in Bilbao is not reflected in all these GL periods. This variability in the impact of the GL scenario on radon concentrations is associated with the location of Bilbao: along the Nervion valley and 16 km from the coast. The analysis of three GL periods using 10-min surface meteorological and radon data showed an anomalous increase in radon with the arrival of maritime winds, which is associated with the process of a progressive accumulation of radon concentrations over the coastal area in the previous days, and the displacement of these air masses inland owing to the development of the GL event. Our results consequently identify the impact of GL on urban air quality in the afternoon, along with the fact that the complex layout of this coastal area, with the presence of valleys and mountains, favours the formation of reservoir layers above the coastal and valley areas, thus influencing on daily variability of air pollution concentrations. These increases in radon concentrations do not present a significant impact on human health.

Raspberry Ketone Attenuates Hepatic Fibrogenesis and Inflammation via Regulating the Crosstalk of FXR and PGC-1α Signaling.

Hepatic fibrosis is a compensatory response to chronic liver injury and inflammation, and dietary intervention is recommended as one of the fundamental prevention strategies. Raspberry ketone (RK) is an aromatic compound first isolated from raspberry and widely used to prepare food flavors. The current study investigated the hepatoprotection and potential mechanism of RK against hepatic fibrosis. In vitro, hepatic stellate cell (HSC) activation was stimulated with TGF-β and cultured with RK, farnesoid X receptor (FXR), or peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α) agonist or inhibitor, respectively. In vivo, C57BL/6 mice were injected intraperitoneally with thioacetamide (TAA) at 100/200 mg/kg from the first to the fifth week. Mice were intragastrically administrated with RK or Cur once a day from the second to the fifth week. In activated HSCs, RK inhibited extracellular matrix (ECM) accumulation, inflammation, and epithelial-mesenchymal transition (EMT) process. RK both activated FXR/PGC-1α and regulated their crosstalk, which were verified by their inhibitors and agonists. Deficiency of FXR or PGC-1α also attenuated the effect of RK on the reverse of activated HSCs. RK also decreased serum ALT/AST levels, liver histopathological change, ECM accumulation, inflammation, and EMT in mice caused by TAA. Double activation of FXR/PGC-1α might be the key targets for RK against hepatic fibrosis. Above all, these discoveries supported the potential of RK as a novel candidate for the dietary intervention of hepatic fibrosis.

Reappropriating the communal past: lineage tradition revival as a way of constructing collective identity in Huizhou, China

This article discusses the reappropriation and redefinition of heritage and tradition as a process of purposeful and selective value extraction by various groups at the local level in Huizhou, China, based on case studies. It is a process of continuous accumulation and self-persuasion by empowering specific cultural heritages, thus reinforcing the identity and cognition of the group to which they belong. The recovery of lineage worship to negotiate different cultural meanings and gain discursive power in the village of Huangdun reveals the counterbalance of the distribution of benefits among lineage groups, locals and government officials. These heritage empowerment actions fit with the official cultural policy and the vision for cultural orthodoxy, healing the division and creating some benefits for the local community. They also generate potential conflicts between the official and folk levels but are performed with mutual achievement and utilisation rather than unilateral dominance.

Agave Wilt Susceptibility by Reduction of Free Hexoses in Root Tissue of Agave tequilana Weber var. azul Commercial Plants in the Fructan Accumulation Process.

Agave tequilana stems store fructan polymers, the main carbon source for tequila production. This crop takes six or more years for industrial maturity. In conducive conditions, agave wilt disease increases the incidence of dead plants after the fourth year. Plant susceptibility induced for limited photosynthates for defense is recognized in many crops and is known as "sink-induced loss of resistance". To establish whether A. tequilana is more prone to agave wilt as it ages, because the reduction of water-soluble carbohydrates in roots, as a consequence of greater assembly of highly polymerized fructans, were quantified roots sucrose, fructose, and glucose, as well as fructans in stems of agave plants of different ages. The damage induced by inoculation with Fusarium solani or F. oxysporum in the roots or xylem bundles, respectively, was recorded. As the agave plant accumulated fructans in the stem as the main sink, the amount of these hexoses diminished in the roots of older plants, and root rot severity increased when plants were inoculated with F. solani, as evidence of more susceptibility. This knowledge could help to structure disease management that reduces the dispersion of agave wilt, dead plants, and economic losses at the end of agave's long crop cycle.

MODERN PROCESSES IN THE BEADED CHANNELS OF STEPPE RIVERS OF THE KHOPER-BUZULUK PLAIN

Beaded-shaped channels (or chain-of-ponds), characterized by alternating lake-like extensions and narrow runs, are widespread on small rivers of the steppe zone of Russia. Extensions of channels - beads (pools or ponds), with a depth of up to 5-6 m, are of great importance for cattle breeding, providing a watering place during the dry periods of the year, when the flow of small rivers stops. However, the mechanisms of their specific channel shape formation are still debatable: it is explained by uneven siltation of channels, formation of whirlpools, groundwater discharge, karst processes or relict thermokarst. The aim of the study was to assess the role of water flow in the formation and support of the beaded shape of river channels. The tasks were to reveal the hydrological regime of the Kardail and Kupava rivers, determine the hydrodynamics of the flow in beads and runs, describe the characteristics of erosion and accumulation processes and the sediment transport, as well as to identify relict elements of the channel and floodplain structure that do not correspond to modern water state. Water flow of the studied rivers shows a long-term decrease in snowmelt flood, as evidenced by the rare flooding of the high-level floodplain, low rates of bank dynamics, and the discrepancy between the size of meanders and the width of the channel. The annual sediment load of the studied beaded rivers is low, estimated at 6,05 t/km2 in 2023. The reason is a low supply of sediments from the catchment area and low rates of erosion of channel bed and banks built of clay and silt. The present-day dynamics of water flow do not help the deepening and expansion of the beads. The flow reaches maximum speed (up to 1-1,3 m/s) in channel runs, while in channel extensions flow speeds drop to 0-0,3 m/s, supporting the sediment accumulation, despite the presence of whirlpools. A significant part of channel extensions is located on sites of former pools of the ancient meandering channel, inherited by the modern watercourse. On the former riffles the channel narrowed and a low-level floodplain was formed. Deep channel extensions were preserved due to the low sediment load and its fine composition, which prevents its rapid settling from the suspension. The results of the study suggest possible contribution of other factors to the formation of original deep pools, including the cryogenic ones.

Fate and potential ecological risk of rare earth elements in 3000-year reclaimed soil chronosequences

The introduction of anthropogenic inputs into natural systems may lead to enduring alterations in the innate characteristics of Rare Earth Elements (REEs). Against this backdrop, the evolutionary processes and environmental drivers of REEs in soil remain uncertain. A 3000-year soil chronosequence with uniform parent material was established in reclaimed farmland along the Yangtze River, reconstructing, for the first time, the dynamic processes of REE accumulation and fractionation over a long-time scale. Analysis of 122 soil samples showed REE concentrations ranging from 146.00 to 216.56 μg/g. Based on reclamation duration, three significant stages of REE evolution were identified: natural leaching, rapid accumulation, and stable accumulation with differentiation. Reclaimed soil after 3000 years exhibited a 14.1 % increase in REE concentrations compared to fresh sediments, attributed to anthro -pedogenic processes. Moreover, Heavy Rare Earth Elements (HREEs) accumulated faster than Light Rare Earth Elements (LREEs), particularly in deeper soils (60–100 cm), where HREE concentrations rose by 34.3 %, mainly due to acidic environments promoting HREE fixation. Additionally, the potential ecological risk posed by REEs heightened with reclamation duration, with HREEs exhibiting a sensitivity of 83 % to 94 %. Our findings stress the urgency of carefully monitoring exogenous REEs introduced through anthropogenic activities, particularly HREEs.

Microplastic pollutants in sediments from a water supply reservoir: Spatial heterogeneity in abundance, characteristics and pollution evaluation

When assessing microplastics (MPs) in freshwater ecosystems, previous studies have primarily focused on natural rivers and lakes, with limited attention to urban water source areas. Sediments, recording the steady process of MPs accumulation during a long period of time, can act as an important sink for MPs. In this study, we investigated the distribution, characteristics and pollution evaluation of MP contaminants in sediments of a water supply reservoir of Hefei City (the Dafangying Reservoir). Meanwhile, the differences of MP concentrations in sediments in rural and urban areas were also compared. Our results detected five shapes, seven colors and six polymer types of MPs in sediments of the Dafangying Reservoir. Polystyrene, polyethylene and polypropylene were the most abundance types of MPs identified. The average MPs abundance of sediments in rural areas was 83.20 ± 32.99 n/100 g dry weight (d.w.), and 182.67 ± 72.21 n/100 g (d.w.) in urban areas. The total MP concentrations were significantly higher in sediments of urban sites than that in rural sites, which can be ascribed to more complex and diverse MP sources triggered by intensive anthropogenic activity in cities. Specifically, we also demonstrated significantly higher microbead abundance in urban sites, which may result from the widespread use of microbead in personal care products. Given the complexity and diversity of MPs in urban areas, we exhibited a relatively higher abundance of MPs in the Dafangying Reservoir than that in other rural larger reservoirs. According to the index of geoaccumulation, the sedimentary MPs were assessed as moderately polluted. Our study enriches valuable data on the distribution of MPs contaminants in water supply reservoir, and provides theoretical references for MPs control and management in reservoir ecosystems.

Effect of quercetin on oxidative stress in 3T3-L1 mature and hypertrophic cells

Abstract Purpose: The process of excessive or abnormal accumulation of fat in the body is called obesity, and its prevalence is increasing globally. The imbalance between antioxidants and free radicals, or oxidative stress, can be caused by or result from obesity. Flavonoids with antioxidant potential may help lower the increased oxidative stress associated with obesity. This study aimed to determine how quercetin affected oxidative stress in hypertrophied and mature 3T3-L1 adipocytes. Materials and methods: After differentiating, 3T3-L1 adipocytes were treated with insulin and a glucose-containing medium to become mature (10 days) and hypertrophic (18 days). The cells were subsequently incubated with 80 µM quercetin for 24 and 48 hours. ELISA was used to determine the levels of total antioxidant capacity/total oxidant capacity (TAS/TOS). Using Oil Red O staining, an accumulation of triglycerides in cells was examined. Results: It was shown that the quercetin molecule had a prooxidative effect on hypertrophic adipocytes but did not impact on oxidative stress in mature adipocytes. Conclusion: It is believed that the number and kind of fat cell will determine the appropriate dose and duration of administration for quercetin's antioxidant mechanism of action, which produces numerous beneficial effects.

Investigating hydrological recovery in regenerating coniferous stands in snow‐dominated watersheds using simultaneous localization and mapping‐enabled mobile terrestrial LiDAR

AbstractThe return of snow accumulation and ablation processes in regenerating forests to pre‐disturbance conditions, collectively referred to as hydrological recovery, has been investigated in past decades through manual snow surveys in adjacent open, juvenile, and mature stands. The outcomes of such studies provide a general understanding of hydrological recovery but lack transferability to areas where stand structure and terrain conditions differ from the reference sites. The application of mobile terrestrial LiDAR to investigate peak snow water equivalent (SWE) and ablation rates beneath regenerating trees in a space‐for‐time substitution study design provides new insights on the process of hydrological recovery in snowmelt forests of British Columbia, Canada. Outcomes of this study better quantify the influence of tree growth on peak SWE and ablation rate at both the tree and stand level for north aspect mixed conifer stands. Recovery of these two processes differ with recovery of Peak SWE beginning when the trees in a stand reach 3 m in height and recovery of ablation rates beginning once trees reach 5 m in height. Additionally, the process of negative ablation recovery in early juvenile stands reported in previous studies is herein clearly observed, providing an improved understanding of forest canopy effects on hydrological recovery in juvenile stands. The methods used in this study, which are internationally applicable, increase transferability of outcomes to stands where canopy characteristics (i.e., height, crown cover, and heterogeneity) are not represented in reference sites.

ИСТОРИЯ ИЗУЧЕНИЯ ПОСЕЛЕНЧЕСКИХ ПАМЯТНИКОВ САРМАТСКОГО ВРЕМЕНИ В ЛЕСОСТЕПНОМ ПОДОНЬЕ

The article reveals the history of the study of hillforts and settlements of the first centuries AD on the Upper Don. The author substantiates the identification of three chronological stages in the history of settlement archeology of the Upper Don region. The first of them is associated with pre-revolutionary studies of local history societies, as well as with the work of the Upper Don expedition in the Lipetsk region and the expedition of the Voronezh State University in the Voronezh region. At this time, the process of accumulation of material from the first centuries took place, and its interpretation was limited to the term “early Iron Age”. The second stage of research began in 1978 with the creation of the Scythian-Sarmatian brigade of VSU (A.P. Medvedev) and its targeted study of burial mounds and settlements of the Sarmatian period in the forest-steppe Don region. During the same period, work was carried out by the LGPI expedition (A.N.Bessudnov), State Directorate for the Protection of Cultural Heritage of the Lipetsk Region (I. E. Biryukov, I. A. Kozmirchuk), as well as employees of the Department of Archaeology and History of the Ancient World of VSU (Yu. D. Razuvaev, M. V. Tsybin, A. S. Savrasov, A. D. Pryakhin, N. A. Tropin, etc.). The third stage is distinguished by the work of both scientific expeditions (A. M. Oblomsky, I. E. Biryukov, G. L. Zemtsov, Yu. D. Razuvaev, D. V. Akimov, etc.) and protective archaeological excavations. Discussions on the identification of groups of hillforts and settlements of the Sarmatian period are considered, and controversial issues of their dating are identified. From the historiographical analysis of the current state of the problem, further directions of its research logically follow: highlighting the cultural uniqueness of the settlements of the Upper Don and, especially, their chronology.

Boosting arousal and cognitive performance through alternating posture: Insights from a multi-method laboratory study.

This study investigated the role of arousal and effort costs in the cognitive benefits of alternating between sitting and standing postures using a sit-stand desk, while measuring executive functions, self-reports, physiology, and neural activity in a 2-h laboratory session aimed to induce mental fatigue. Two sessions were conducted with a one-week gap, during which participants alternated between sitting and standing postures each 20-min block in one session and remained seated in the other. In each block, inhibition, switching, and updating were assessed. We examined effects of time-on-task, acute (local) effects of standing versus sitting posture, and cumulative (global) effects of a standing posture that generalize to the subsequent block in which participants sit. Results (N = 43) confirmed that time-on-task increased mental fatigue and decreased arousal. Standing (versus sitting) led to acute increases in arousal levels, including self-reports, alpha oscillations, and cardiac responses. Standing also decreased physiological and perceived effort costs. Standing enhanced processing speed in the flanker task, attributable to shortened nondecision time and speeded evidence accumulation processes. No significant effects were observed on higher-level executive functions. Alternating postures also increased heart rate variability cumulatively over time. Exploratory mediation analyses indicated that the positive impact of acute posture on enhanced drift rate was mediated by self-reported arousal, whereas decreased nondecision time was mediated by reductions in alpha power. In conclusion, alternating between sitting and standing postures can enhance arousal, decrease effort costs, and improve specific cognitive and physiological outcomes.

Geochemistry and zircon U-Pb geochronology of diabase, gabbros, anorthosites and ultramafic rocks from the South Andaman Island ophiolite suite on the South-Eastern margin of the Indian plate

The South Andaman Island is located on the southeastern fringe of the Indian plate. Tectonically, the islands are associated with the Burma-Andaman-Java subduction zone of the Indonesian arc system. Several Mesozoic ophiolitic exposures are preserved in the Burma-Andaman-Java subduction zone. This study reports new petrological, geochemical, and zircon U-Pb geochronological data for the diabases, gabbros, anorthosites, and harzburgites of the ophiolite suite exposed in the South Andaman Island. The diabase is composed of plagioclase and clinopyroxene exhibiting ophitic textures. Anorthosite mainly contains plagioclase (> 90 vol%), pyroxenes and Fe-oxides. Gabbros have plagioclases and clinopyroxenes occurring as the major minerals. Harzburgites consist of olivine, orthopyroxene, clinopyroxene and spinel. Geochemical investigation reveals that these rocks were formed through crystal fractionation and accumulation processes from partial melt generated from a spinel lherzolite source. Gabbro, diabase, and anorthosites are formed by ∼1–5% melting of the, whereas depleted harzburgites were generated by slightly higher degrees of partial melting (∼10–20%) of the spinel lherzolite source. Trace element modelling reveals the influence of mid-oceanic ridge basalt (MORB)-melt interaction and subduction-related mantle alterations.The anorthosite and gabbro samples yield zircon 206Pb / 238U weighted mean ages of 93.2 ± 1.0 Ma and 442.5 ± 4.0 Ma, 383.9 ± 3.3 Ma respectively. However, the harzburgite sample records multiple age population including Paleo-Mesoproterozoic grains ranging in age from 1216 to 1931 Ma as well as Neoproterozoic and Phanerozoic grains of 607 Ma, 594 Ma, 237 Ma, 105 Ma, and 85 Ma suggesting a long-lived supra subduction zone in the Burma-Andaman-Java subduction zone where the South Andaman ophiolite suite was formed, evolved, and was emplaced.

A systematic review of the role of TREM2 in Alzheimer's disease.

Given the established genetic linkage between triggering receptors expressed on myeloid cells 2 (TREM2) and Alzheimer's disease (AD), an expanding research body has delved into the intricate role of TREM2 within the AD context. However, a conflicting landscape of outcomes has emerged from both in vivo and in vitro investigations. This study aimed to elucidate the multifaceted nuances and gain a clearer comprehension of the role of TREM2. PubMed database was searched spanning from its inception to January 2022. The search criteria took the form of ("Alzheimer's disease" OR "AD") AND ("transgenic mice model" OR "transgenic mouse model") AND ("Triggering receptor expressed on myeloid cells" OR "TREM2"). Inclusion criteria consisted of the following: (1) publication of original studies in English; (2) utilization of transgenic mouse models for AD research; and (3) reports addressing the subject of TREM2. A total of 43 eligible articles were identified. Our analysis addresses four pivotal queries concerning the interrelation of TREM2 with microglial function, Aβ accumulation, tau pathology, and inflammatory processes. However, the diverse inquiries posed yielded inconsistent responses. Nevertheless, the inconsistent roles of TREM2 within these AD mouse models potentially hinge upon factors such as age, sex, brain region, model type, and detection methodologies. This review substantiates the evolving understanding of TREM2's disease progression-dependent impacts. Furthermore, it reviews the interplay between TREM2 and its effects across diverse tissues and temporal stages.

Using In Vitro Cultured Berries to Unravel the Effects of Heat- and ABA-Induced Stress on Thiol Precursor Biosynthesis in Sauvignon Blanc.

Global warming, heat waves, and seasonal drought pose serious threats to crops, such as grapevine, that are valued for their secondary metabolites, which are of primary importance for the wine industry. Discriminating the effects of distinct environmental factors in the open field is challenging. In the present study, in vitro cultured berries of Sauvignon Blanc were exposed to individual and combined stress factors to investigate the effects on the biosynthesis of the thiol precursors. Our results confirm the complexity and extreme reactivity of the accumulation process in grapes. However, they also indicate that heat stress has a positive effect on the production of the Cys-3SH precursor. Moreover, we identified several candidate genes, such as VvGSTs and VvGGT that are potentially involved in biosynthesis and consistently modulated. Nonetheless, we were unable to conclusively determine the effects of stresses on the biosynthesis of other precursors nor could we formulate hypotheses regarding their regulation.

Arbuscular mycorrhizal fungi increase the tolerance to excess zinc of a tropical legume grown in iron-ore mining waste

Arbuscular mycorrhizal fungi (AMF) might amend the toxicity of trace elements and improve the nutritional status of plants, but little is known about these responses in tropical native plants in iron-ore-impacted sites with excess zinc (Zn). We evaluated how the association with AMF contributes to the resistance capacity of Stryphnodendron adstringens to high Zn concentrations in mining waste. Seeds were sown in pots containing iron-ore mining waste with different concentrations of Zn (0, 100, 200, 400 and 600 mg L−1) and two conditions (inoculated or not with AMF). The biomass accumulation and physiological processes were severely impacted in the mining waste with Zn concentration above 100 mg L−1. The relative growth rate (RGR) and the concentration of phosphorus (P) in the shoot were higher in the AMF-inoculated plants, mainly when cultivated without Zn excess. Non-inoculated plants presented the lowest net photosynthetic rate (An) mainly due to impairment in light use efficiency, especially under Zn excess. The treatments did not change stomatal conductance, transpiration, Rubisco carboxylation rate, triose-phosphate utilization and respiration rate. The AMF improved the plant resistance capacity in mining waste substrate by promoting decreased oxidative damage, ameliorated P nutrition, higher RGR, root biomass and An.

RIGHT TO ENVIRONMENTAL INFORMATION IN THE CONTEXT OF DIGITALIZATION

The article examines the legal signi cance of environmental information in a digital society and examines its characteristics such as reliability. It is this quality of information about the state of the environment that is enshrined in the Constitution of the Russian Federation. It is noted that reliable information about the state of the environment is information that is at the same time genuine (objective, undistorted, accurate), and su cient (not excessive, but not fragmentary and not selective), and relevant (timely), unbiasedly collected and analyzed by a competent subject. The de nition of the term “information on the state of the environment (environmental information)” included in the Federal Law “On Environmental Protection” in 2021 is also analyzed. It is concluded that the legal de nition of the term in question does not allow distinguishing environmental information from all other information. The right to environmental information is analyzed in relation to the modern system of information support for state environmental management. The necessity of establishing a regime of transparency of information on the state of the environment is substantiated. It is proposed to develop and implement an information mechanism in the eld of environmental protection - a system of information measures of in uence (interrelated legal means that mediate the processes of collection, accumulation, analysis, storage, provision and use of reliable environmental information) on people’s behavior in order to ensure environmental protection, rational use of natural resources, environmental safety of humans and other objects.

CEMENTITIOUS SYSTEMS FOR HIGH-PERFORMANCE CONCRETES WITH IMPROVED CORROSION RESISTANCE

The article presents the results of research on cementitious systems "Portland cement CEM I 42,5 R - active mineral additives - microfillers - superplasticizer - hardening accelerators" for high-performance concrete with improved corrosion resistance. The resistance of concrete to corrosion caused by the influence of chemical substances was investigated - sulfate corrosion (class XA), which combines the processes of formation and accumulation of sparingly soluble salts in concrete, which are accompanied by internal stresses and destructive phenomena in concrete. The increase in corrosion resistance of high-performance concretes based on modified cementitious systems is explained mainly by the creation of a fine-crystalline microstructure with the formation of C-S-H phases, which contribute to the pores colmatation with age of hardening.

Bessel beam fabrication of graphitic micro electrodes in diamond using laser bursts

We present the fabrication of conductive graphitic microelectrodes in diamond by using pulsed Bessel beams in the burst mode laser writing regime. The graphitic wires are created in the bulk of a 500 μm thick monocrystalline HPHT diamond (with (100) orientation) perpendicular to the sample surface, without beam scanning or sample translation. In particular, the role of different burst features in the resistivity of such electrodes is investigated for two very different sub-pulse durations namely 200 fs and 10 ps, together with the role of thermal annealing. Micro-Raman spectroscopy is implemented to investigate the laser-induced crystalline modification, and the results obtained by using two different laser repetition rates, namely 20 Hz and 200 kHz, are compared. A comparison of the micro-Raman spectra and of the resistivity of the electrodes fabricated respectively with 10 ps single pulses and with bursts (of sub-pulses) of similar total duration has also been made, and we show that the burst mode writing regime allows to fabricate more conductive micro electrodes, thanks to the heat accumulation process leading to stronger graphitization. Moreover, the microfabrication of diamond by means of the longest available bursts (~ 46.7 ps duration) featured by 32 sub-pulses of 200 fs duration, with intra-burst time delay of 1.5 ps (sub-THz bursts), leads to graphitic wires with the lowest resistivity values obtained in this work, especially at low repetition rate such as 20 Hz. Indeed, micro electrodes with resistivity on the order of 0.01 Ω cm can be fabricated by Bessel beams in the burst mode regime even when the bursts are constituted by femtosecond laser sub-pulses, in contrast with the results of the standard writing regime with single fs pulses typically leading to less conductive micro electrodes.

Analysis of corrugation development on a Tianjin metro straight line focusing on wheel-rail contact mechanics

The development features of corrugation on the straight track metro line are studied to find the root cause of corrugation. Firstly, the measured corrugation characteristics on the line are investigated and a three-dimensional wheel-rail (WR) rolling contact finite element (FE) model is constructed. Then, the WR stick-slip (SS) characteristics, WR contact and rail wear are analyzed to understand the evolution process of corrugation from the micro transient point of view. Finally, combined with a system stability analysis, the development trend of corrugation is characterized from the macro perspective. The results show that the WR contact has a significant SS variation under the corrugation condition, which promotes the initial corrugation to develop further. For the fixed node in the contact area on the rail surface, the maximum stress and strain of the section where it is located will gradually transfer from the subsurface to the surface with the wheel running, so the damage prone position will also form first on the subsurface and gradually transfer to the surface. This shows from the micro viewpoint that the formation of wave crest/trough in the corrugation section is a bottom-up process of damage accumulation. The corresponding frequency of 648 Hz of the unstable vibration mode in the WR system is close to the passing frequency of 656 Hz of measured corrugation, demonstrating that the initial corrugation will tend to intensify with the wheel running.