Sampling Depth Research Articles

Turfgrass species and sward age influence soil carbon pools near the soil surface

AbstractEnhancing soil carbon (C) sequestration helps reduce atmospheric carbon dioxide concentrations. Turfgrasses are important crops in the urban environment and have shown potential for C sequestration. However, little is known about how turfgrass species selection affects soil C concentration or how this varies over time. The objectives of this research were to evaluate the effect of three turfgrass species, sward age, and soil sampling depth on total soil C and N, soil organic matter (SOM), and labile soil C. A total of 25 locations throughout Indiana were sampled from established swards of Kentucky bluegrass (Poa pratensis L.), tall fescue [Festuca arundinacea Schreb.; syn. Schedonorus arundinaceus (Schreb.) Dumort., nom. cons.], and zoysiagrass (Zoysia japonica Steud.) with varying sward age. Turfgrass species affected soil total C and labile C concentrations but had no effect on soil total nitrogen (N) or SOM. Differences between the C pools of soils under turf 0–10 years in age compared to those 11–25 years in age only occurred near the soil surface. As turf swards age, total soil C, total soil N, and SOM increased near the soil surface (0‐ to 7.5‐cm depth) and little beyond the 7.5 cm in depth. The strong relationship (p ≤ 0.0001, R2 > 0.57) between total N, SOM, and labile C highlighted their interplay in the mineralization of N from SOM and changes in the short‐term C pool of a turfgrass system.

A brief history of the development of transcranial tissue Doppler ultrasound.

This article documents the early development of the first transcranial Doppler (TCD)-based ultrasound system for continuous monitoring of brain tissue pulsations (BTPs). Transcranial tissue Doppler (TCTD) uses a lightweight, wearable single-element ultrasound probe to track tissue motion perpendicular to the skin's surface, providing tissue displacement estimates along a single beam line. Feasibility tests using an adapted TCD system confirmed that brain tissue motion data can be obtained from existing TCD hardware. Brain Tissue Velocimetry (Brain TV), a TCTD data acquisition system, was then developed to provide a lightweight and portable means of continuously recording TCTD data in real-time. Brain TV measurements are synchronized to a 3-lead electrocardiogram and can be recorded alongside other physiological measurements, such as blood pressure, heart rate and end-tidal carbon dioxide. We have shown that Brain TV is able to record BTPs from sample depths ranging from 22 to 80 mm below the probe's surface and from multiple positions on the head. Studies in healthy volunteers, stroke patients and ultrasound phantom brain models demonstrate how TCTD might provide insights into the relationships between physiological measurements and brain tissue motion and show promise for rapid clinical assessment and continuous monitoring of BTPs.

Global soil microplastic assessment in different land-use systems is largely determined by the method of analysis: A meta-analysis

Although microplastics (1 μm - 5 mm, MP) are increasingly recognised as a novel entity of pollutants, we still lack a basic understanding of their prevalence in different terrestrial environments. Here, we aimed at performing comparisons of MP concentrations (items kg−1) in different agro-ecosystems, with specific focus on input pathways and land uses, while accounting for the plethora of method variations available, such as analysed MP sizes, sampling depths, density separation solutions, as well as removal of organic matter. We found that the current global means of MP loads, from 89 studies (553 sites), benchmarks 2900 ± 7600 MP items kg−1 soil, substantially more than the global median of 480 MP items kg−1. Roughly 81 % of the studies were conducted in Asia; hence, continent-wider comparisons are still hampered by low study numbers for most regions. Maximum MP numbers were found for soils under both greenhouses and plastic mulching (5200 ± 8300 items kg−1), followed by arable soils with sludge amendments (3700 ± 8800 items kg−1), surprisingly without evidence of elevated MP loads in horticultural fields relative to other agricultural management practices. Intriguingly, global MP loads significantly increased with decreasing levels of urbanisation, i.e., they were highest in rural areas. Yet, quantitative comparisons among sites are biased by the methodology selected for MP analyses. Apart from inconsistencies in sampling depth and size of screened MP particles, across all sites and treatments, largest MP loads were commonly found when using high-density solutions rather than low-density ones, and when soil organic matter removal was performed after and not before the density separation step.

The transport and vertical distribution of microplastics in the Mekong River, SE Asia

Rivers are primary vectors of plastic debris to oceans, but sources, transport mechanisms, and fate of fluvial microplastics (<5mm) remain poorly understood, impeding accurate predictions of microplastic flux, ecological risk and socio-economic impacts. We report on microplastic concentrations, characteristics and dynamics in the Mekong River, one of the world’s largest and polluting rivers, in Cambodia and Vietnam. Sampling throughout the water column at multiple localities detected an average of 24 microplastics m-3 (0.073mgl-1). Concentrations increased downstream from rural Kampi, Cambodia (344km from river mouth; 2 microplastics m-3, 0.006mgl-1), to Can Tho, Vietnam (83km from river mouth; 64 microplastics m-3, 0.182mgl-1) with most microplastics being fibres (53%), followed by fragments (44%) and the most common polymer being polyethylene terephthalate (PET) or polyester. Pathways of microplastic pollution are expected to be from urban wastewater highlighting the need for improved wastewater treatment in this region. On average, 86% of microplastics are transported within the water column and consequently we identified an optimum sampling depth capturing a representative flux value, highlighting that sampling only the water surface substantially biases microplastic concentration predictions. Additionally, microplastic abundance does not linearly follow discharge changes during annual monsoonal floods or mirror siliclastic sediment transport, as microplastic concentrations decrease rapidly during higher monsoon flows. The findings reveal complex microplastic transport in large rivers and call for improved sampling methods and predictive models to better assess environmental risk and guide policy.

The effect and mechanism of digital economy on green total factor productivity — Empirical evidence from China

In the context of global digitalization, it is of great significance to promote the development of digital economy to reduce carbon emissions and improve green total factor productivity (GTFP). Based on the data of 30 provinces in China from 2011 to 2021, this study constructs a variety of methods, such as Super-SBM model, fixed effect model and intermediary effect model, to empirically test the impact and mechanism of digital economy (DIE) on GTFP. Based on the research findings, the growth of DIE contributes to the improvement of GTFP. Moreover, the impact of DIE on GTFP in eastern China is greater than that in central and western China. There are significant differences between the development level of DIE and GTFP in eastern, central and western regions. Further research shows that digital economy affects the improvement of GTFP through three intermediary variables: economic scale, industrial structure and technological innovation. This study provides empirical evidence to support the effective enhancement of GTFP in developing countries as the digital economy evolves. It provides effective recommendations for developing countries and emerging economies to develop a green economy. However, this study has limitations in data sample, research scope and mechanism analysis depth. Therefore, the conclusions drawn in this study can only provide empirical evidence for identifying the relationship between the DIE and GTFP to a certain extent. Future research should be expanded in these aspects.

Physical and mechanical depth relationships of rocks from the Rotokawa Geothermal Reservoir, Taupō Volcanic Zone, New Zealand

ABSTRACT The Rotokawa geothermal field is in the Taupō Volcanic Zone, New Zealand. It hosts two geothermal power plants, Rotokawa and Ngā Awa Pūrua, which together have a capacity over 170 MWe. The permeability of the rock mass comprising a geothermal field controls the volume of hot fluids that can be extracted for energy production. In this research we produce a stress model to estimate in-situ rock matrix permeability for a unique set of intact rock samples obtained from depths up to 2600 m in the Rotokawa geothermal field. We show that permeability generally decreases with sample depth, both intrinsically and in response to increasing confining pressure. We explore this confining pressure effect on other petrophysical and mechanical measurements, and highlight how rock texture and composition affect how the rocks respond to confining pressure. For example, we compare two altered andesite samples: a breccia with microfractures and infilled pores that tends to experience less compaction and porosity decrease than a lava with rounded, unfilled pores. We suggest that, when developing depth-models, measurements should be conducted at relevant in-situ conditions, if possible. Finally, we explore relationships between different physical parameters and provide estimating functions for those with the clearest correlations.

Soil nutrient stocks in areas where oiticica (Licania rigida Benth) occurs in the paraiba hinterland

The experiment was conducted in the municipalities of Catolé do Rocha and Pombal, both located in the state of Paraíba in northeastern Brazil. The areas are composed of Eutrophic Fluvic Neosols, with low-activity clay and high natural fertility in flat relief. The factorial arrangement was 2x2, with a completely randomized design, with two municipalities: Catolé do Rocha and Pombal and two soil sampling depths: 0–20 cm and 20–40 cm, selecting 10 matrices of oiticica, L. rigida Benth, representing 10 replicates. In the municipality of Catolé, soil analysis revealed higher SB and CTC with lower pH and MOS compared to the municipality of Pombal. The chemical characterization of the soil in the surface layers presents higher concentrations of nutrients than in the subsurface layers, mainly regarding the levels of MO, reflecting in higher levels of phosphorus, sum of bases and cation exchange capacity.

MARS CHRONOLOGY DERIVED FROM CRATERS HETEROGENEITY AT GALE CRATER

Craters sample into diachronic surfaces and different depths on Mars and other planetary surfaces. These surfaces are affected by cosmonuclide radiation that offers one of the most reliable age anchors to date. Craters also accumulate, evolve and display an universal characteristic that can be measured at any scale, regardless of the geologic unit they sample, in the form of the heterogeneity parameter (Capitan, 2021). Here we use an age equation, which is based on the measurements of craters diameter, depths and area they occupy, to derive the ages of deposits that are sampled by medium-scale craters (meters to few hundred meters in diameter). We show that units sampled by the deepest craters near MSL exploration area are formed during the early stages of Gale crater formation before 2870 Ma. In contrast, units sampled by shallower craters were formed during the stages that correspond to the time of sediment recycling and lithification periods, near 2129 Ma to present. Given the heterogeneity of initial formation conditions of craters of diverse diameters and their different depths of sampling, our proposed synchronous ages with ground-truth ages has the potential to redefine the paradigm of using the impact crater morphometry as a tool to date the planetary surfaces.

Assessment of soil gas radon migration and transport through the estimation of radon diffusion length and diffusion coefficient in the soil matrix

Naturally occurring radioactive gas, radon is a decay product of radium present in the soil. Radon flux reaches the atmosphere through exhalation from soil surface. This study aims to estimate the radon diffusion length and diffusion coefficient in soil matrix on the premises of HNB Garhwal University campus at Tehri Garhwal, India. Soil gas radon concentration was measured at different depths (15, 30, 45, 60, 75, and 90 cm) using a Smart RnDuo (Scintillation-detector) at 14 different locations in the university campus. Simultaneous measurement of surface and mass exhalation rates was also carried out for each location. Gamma-ray spectrometry was used to estimate the radium content in soil samples. Results of the present study suggest that soil gas radon concentration increases with increasing sampling depth. The diffusion coefficient and length were calculated using the soil gas radon concentration gradient within the soil matrix. The average value of diffusion length (l) and diffusion coefficient (D) were obtained as, ls = 0.70 ± 0.22 m, Ds = 0.0054 ± 0.0049 m2 sec-1 and la = 0.77 ± 0.63 m, Da = 0.0073 ± 0.014 m2 sec-1 by Fick’s diffusion model and analytic models, respectively.

A Review of the Basic Principles and Methods of Signal Sampling Technology

In modern life, communication is an essential human activity. In the process of communication, various information spreads around the world in the form of signals. In order to optimize the communication, the reasonable processing of the signal becomes an important research problem. Signal processing is an important step during signal processing. It is one of two processes that convert an analog signal into a digital equivalent signal. It can be considered that signal sampling transforms the time axis of the signal into a set of discrete time moments, that is, the process of converting a signal in a continuous time domain to a discrete time domain through a series of methods. It is used to convert continuous time signals into digital signals for relevant processing and storage of digital signals in subsequent operations. This paper will summarize the basic principles and methods of signal sampling technology, introduce the sampling theorem, sampling frequency, sampling depth, sampling method and sampling error, and finally discuss the future development of signal adoption technology.

Taxonomic variation, plastic degradation, and antibiotic resistance traits of plastisphere communities in the maturation pond of a wastewater treatment plant.

Wastewater treatment facilities can filter out some plastics before they reach the open environment, yet microplastics often persist throughout these systems. As they age, microplastics in wastewater may both leach and sorb pollutants and fragment to provide an increased surface area for bacterial attachment and conjugation, possibly impacting antimicrobial resistance (AMR) traits. Despite this, little is known about the effects of persistent plastic pollution on microbial functioning. To address this knowledge gap, we deployed five different artificially weathered plastic types and a glass control into the final maturation pond of a municipal wastewater treatment plant in Ōtautahi-Christchurch, Aotearoa/New Zealand. We sampled the plastic-associated biofilms (plastisphere) at 2, 6, 26, and 52 weeks, along with the ambient pond water, at three different depths (20, 40, and 60 cm from the pond water surface). We investigated the changes in plastisphere microbial diversity and functional potential through metagenomic sequencing. Bacterial 16S ribosomal RNA genes composition did not vary among plastic types and glass controls (P = 0.997) but varied among sampling times [permutational multivariate analysis of variance (PERMANOVA), P = 0.001] and depths (PERMANOVA, P = 0.011). Overall, there was no polymer-substrate specificity evident in the total composition of genes (PERMANOVA, P = 0.67), but sampling time (PERMANOVA, P = 0.002) and depth were significant factors (PERMANOVA, P = 0.001). The plastisphere housed diverse AMR gene families, potentially influenced by biofilm-meditated conjugation. The plastisphere also harbored an increased abundance of genes associated with the biodegradation of nylon, or nylon-associated substances, including nylon oligomer-degrading enzymes and hydrolases.IMPORTANCEPlastic pollution is pervasive and ubiquitous. Occurrences of plastics causing entanglement or ingestion, the leaching of toxic additives and persistent organic pollutants from environmental plastics, and their consequences for marine macrofauna are widely reported. However, little is known about the effects of persistent plastic pollution on microbial functioning. Shotgun metagenomics sequencing provides us with the necessary tools to examine broad-scale community functioning to further investigate how plastics influence microbial communities. This study provides insight into the functional consequence of continued exposure to waste plastic by comparing the prokaryotic functional potential of biofilms on five types of plastic [linear low-density polyethylene (LLDPE), nylon-6, polyethylene terephthalate, polylactic acid, and oxygen-degradable LLDPE], glass, and ambient pond water over 12 months and at different depths (20, 40, and 60 cm) within a tertiary maturation pond of a municipal wastewater treatment plant.

Subsoil testing required to detect the rundown of soil potassium to deficient levels for wheat production on loam-textured soils

Context Long-term negative potassium (K) balances in crop production have depleted soil K levels in Western Australia (WA). Previous research has focussed on sand-textured soils, but recently, monitoring of crops grown on loam-textured soils has shown deficient or marginal shoot K concentrations where Colwell K 0–10 cm is above current critical levels. Aims The aims were to examine whether grain yield responses to fertiliser K can be detected on loam-textured soils and if soil test calibration curves can be identified for these soils. Methods Eight field trials were conducted with wheat on loam-textured soils. The same experimental design was used at all sites; six levels of K applied at sowing, from 0 to 200 kg K ha−1 with one treatment including a split application. Soil and plant test calibration curves were modelled using measurements from the trials. Key results Grain yield responses of 0.69 to 1.37 t ha−1 to fertiliser K (P &lt; 0.05) occurred in 4 of 8 trials. Relative yield was closely related to soil exchangeable K and the goodness of fit of the soil test calibration curves increased as the depth of sampling increased. The best soil test calibration curve was for sampling 0–40 cm. Conclusions This research confirms that on some loam-textured soils, yield loss is occurring to K deficiency if no K fertiliser is applied. Implications As soil K reserves are run down, soil sampling at 0–40 cm on loam-textured soils will provide the most accurate monitoring of soil K deficiency for wheat production.

ATR-FTIR spectroscopic imaging with variable angles of incidence of crude oil deposits formed by flocculant flow

Attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopic imaging is a method for spatially resolved analysis of materials that combines the capabilities of ATR-FTIR spectroscopy with the use of a focal plane array detector. This paper presents the methodological aspects of adapting the ATR accessory with variable single reflection angle to the FTIR spectroscopic imaging method. The use of a variable reflection angle allows the image to be studied at different sample depths. Using examples of BMIMPF6 ionic liquid and crude oil droplets placed on the working surface of an internal reflection element, the characteristics of image acquisition as the angle of reflection is varied are discussed. The possibility of obtaining crude oil deposits directly on the working surface of the internal reflection element under the influence of a flocculant flow (n-heptane, acetone) and their study by ATR-FTIR spectroscopic image was demonstrated. Crude oil deposits were obtained under different formation conditions (flow rates of flocculant) and their spectroscopic images were also obtained at different single reflection angles. This information gives an indication of the composition of the deposit’s functional groups not only at spatial resolution but also at depth.

Ordering-facilitated lower hydrogen embrittlement sensitivity in a prototype high-entropy alloy

The ageing treatment (450 °C/60 h) led to the spinodal decomposition at grain boundaries (GBs) and the development of chemical short-range orders (CSROs) in the alloy matrix, increasing the strength and effectively reducing the hydrogen embrittlement (HE) sensitivity of the equiatomic FeMnNiCoCr alloy. Firstly, the emergence of NiMn- and Cr-rich orders at GB regions reduces hydrogen diffusion rates along GBs and limits hydrogen enrichment at these sites. Secondly, CSROs promote hydrogen accumulation within the grain interior and impede hydrogen penetration, resulting in a shallower hydrogen-affected depth in the aged sample. Moreover, the modulation of hydrogen distribution by microstructure initiates transgranular cracking in the aged sample.

Features of the microbiome of burial soils

Introduction. On the territory of the Russian Federation, as well as worldwide, a large amount of space is allocated for burials. The soils found in the burial areas have their own characteristics. In the scientific literature there is a few works devoted to the problem of hygienic assessment of cemeteries from the point of view of their impact on the environment, as well as on the population living next to necrosols or working on them. Depending on the chemical and biological effects, the microbial composition of the soil changes. This process is influenced by many factors, including humidity, the initial content of organic and mineral substances, level of acidity, structure of the soil and peculiarities of the course of intra-soil gas-phase reactions. The key participants in the decomposition of organic material are bacteria and fungi, the diversity and dynamics of which directly depend on the degree of soil contamination with pollutants. The purpose of this study was to analyze the microbiota of cemetery soil in its various layers. Materials and methods. The cemeteries of Moscow (NikoloKhovanskoye, Nikolo-Arkhangelskoye, Perepechenskoye), Moscow (Mytishchenskoye, Domodedovo), Tula (Municipal Cemetery No. 1 of the Municipal State Enterprise of the Municipal Formation of the City of Tula Combine of Specialized Services), Kursk (old city cemetery Kurchatov), Krasnoyarsk (Zheleznogorsk) regions and Altai (Yarovoye) Krais were selected as research objects for assessing the microbiome of soils. Results. The most common bacterial pathogens were found to be Enterococcus spp. (81%), Bacillus spp. (75%) and E. coli (45.1%). Mushrooms of Penicillium spp.. were isolated from 61% of the samples. The revealed microbiota profiles of the samples of the studied cemetery soils reflect the microbial composition of humans, which allows substantiating the main methods and algorithm for identifying decomposition processes depending on the time frame of burials. Limitations. The limitation of the study is due to the risk of contact with cemetery soil was not assessed, since not all genera of isolated microorganisms could be identified by their biochemical properties. Conclusion. Studies conducted in cemetery areas have shown how diverse the soil microbiome is in burial sites and varies depending on the depth of sampling. The microbiota profiles of cemetery soil samples identified during the study reflect the lifetime microbial composition of the human body, which makes it possible to substantiate approaches to identifying decomposition processes depending on the time frame of burials.

Ultrasound normalized local variance to assess metabolic dysfunction-associated steatotic liver disease

PurposeIncreased prevalence of metabolic dysfunction-associated steatotic liver disease (MASLD) highlights a desire for screening with liver ultrasound normalized local variance (NLV). We aimed to assess variations in NLV values measured at different sampling depths and discuss common technical considerations in measuring liver NLV. MethodsWe retrospectively measured liver NLVs at variable depths on ultrasound images pre-recorded in 116 participants who underwent liver magnetic resonance imaging-proton density fat fraction (MRI-PDFF) and ultrasound to screen for MASLD. Liver NLVs were measured and differences at variable depths were tested using one-way analysis of variance (ANOVA) and multiple paired comparisons using post hoc Tukey honestly significant difference (HSD), Scheffé, Bonferroni, and Holm multiple comparisons. Diagnostic performance of NLV values were analyzed by area under the receiver operating characteristic (AUROC) curve. ResultsThe NLV measured at a depth of 10 cm significantly differed from those measured near the liver capsule and at depths of 6 cm and 8 cm (p < 0.001) from the skin. There was no significant difference in NLV value in other paired groups (p > 0.05). The difference in the area under AUROCs for NLVs measured at variable depths was not significant (p > 0.05). ConclusionsThe best diagnostic performance of liver NLV was measured at depth of 8 cm from the skin, although NLV measured at variable depth showed similar diagnostic performance for assessing ≥ mild hepatic steatosis. The study results provide a reference that can be used in the development of standardized scanning protocols and technical considerations in measuring liver NLV.

Parasitic contamination of environmental objects with nematode eggs of Trichuris genus in the city of Poltava

The spreading of dog digestive tract helminthoses, including trichurosis, still remains a topical problem, where one of the factors of significant infestations’ spreading is the contamination of the environment with parasites’ eggs, which can be preserved in the environment for a long time and cause infestation of susceptible animals. Therefore, one of the important factors in maintaining veterinary well-being in relation to dog trichurosis is establishing the contamination level of environmental objects by propagative stages of nematode development. The purpose of the research was to determine contamination indicators of sand and soil in the city of Poltava with nematode eggs of Trichuris genus. The studies were conducted on the basis of the laboratory of parasitology of Poltava State Agrarian University. Sand samples from sandboxes located on the territory of the city of Poltava, as well as soil from the territories adjacent to them were studied. The main contamination indicators were the extensive contamination index and intensive contamination index. It was revealed by the conducted research that 61 out of 90 sandboxes in the city of Poltava were contaminated with nematode eggs of Trichuris genus, where the extensive contamination index made 67.78 %, and the intensive contamination index made 195.79±18.41 eggs/kg. The territory of Kyiv district was the most contaminated with nematode eggs, where 25 out of 30 sandboxes were contaminated with propagative stages of trichurises development, and the level of parasites’ contamination was 83.33 % and 218.91±17.27 eggs/kg. It was found that the most infected sand was taken from the surface at the edges of the sandbox, near its walls, where the extensive and intensive contamination indices made 41.11 % and 320.27±35.43 eggs/kg, respectively. Also, high rates of parasitic infestation were found during studying the soil, taken from the surface at a distance of 1 m from the sandbox, where, on the average, the extensive contamination index was 46.67 %, and the intensive contamination index was 263.90±28.87 eggs/kg. With an increase in the sampling depth, the indicators of contamination with trichurises’ eggs decreased and amounted to: on the surface – 36.67–46.67 % and 120.37–320.7 eggs/kg, at a depth of 5 cm – 14.44–30.00 % and 80.77–274.07 eggs/kg, and at a depth of 10 cm – 8.89–20.00 % and 62.50–125.00 eggs/kg. The obtained results of parasitological studies prove that the territory of sandboxes is a real factor in the transmission of invasive agents, which must be taken into account in assessing the risks of infecting dogs with trichurosis causative agent.

Arctic tundra soil depth, more than seasonality, determines active layer bacterial community variation down to the permafrost transition

Enhanced microbial decomposition of the Arctic's vast soil carbon pool due to climate warming could result in globally significant CO2/CH4 emissions. Our understanding of tundra soil microbial communities is generally based on studies of either the top surface or the deep frozen permafrost. In contrast, there has been relatively little exploration of bacterial communities and soil biogeochemistry down through entire soil depth profiles to the permafrost, and none that has specifically incorporated temporal dynamics with depth as the summer thaw proceeds. Here we report bacterial community composition in 10-cm increments from the surface to the permafrost from late winter through to autumn, at a mesic low Arctic tundra site. Bacterial community composition and phylogenetic diversity varied substantially with soil depth and much less among sampling times. Correlation analysis indicated that the surface organic, subsoil mineral, and permafrost transition soil layers each had distinct community interaction networks. Acidobacteriota-affiliated taxa dominated surface communities but declined significantly with soil depth and increasing pH, while Bacteroidetes taxa relative abundances were also associated with pH, and were largest in the carbon-restricted permafrost transition layer. Thus, patterns in community assembly were primarily associated with depth and correlated with edaphic factors, with relatively little impact of the seasonal changes between frozen and thawed assemblages within each sampling depth interval. Nevertheless, total microbial biomass within each depth interval generally declined during the seasonal transition from frozen to thawed state. Finally, our data indicate that soil pH, which is known to govern tundra microbial community composition horizontally across the surface organic layer at multiple spatial scales, is also an important determinant of vertical differences in bacterial community composition from the top surface down to the permafrost.

Investigating In Vivo Tumor Biomolecular Changes Following Radiation Therapy Using Raman Spectroscopy.

Treatment resistance is a major bottleneck in the success of cancer therapy. Early identification of the treatment response or lack thereof in patients can enable an earlier switch to alternative treatment strategies that can enhance response rates. Here, Raman spectroscopy was applied to monitor early tumor biomolecular changes in sensitive (UM-SCC-22B) and resistant (UM-SCC-47) head and neck tumor xenografts for the first time in in vivo murine tumor models in response to radiation therapy. We used a validated multivariate curve resolution-alternating least-squares (MCR-ALS) model to resolve complex multicomponent Raman spectra into individual pure spectra and their respective contributions. We observed a significant radiation-induced increase in the contributions of lipid-like species (p = 0.0291) in the radiation-sensitive UM-SCC-22B tumors at 48 h following radiation compared to the nonradiated baseline (prior to commencing treatment). We also observed an increase in the contribution of collagen-like species in the radiation-resistant UM-SCC-47 tumors at 24 h following radiation compared to the nonradiated baseline (p = 0.0125). In addition to the in vivo analysis, we performed ex vivo confocal Raman microscopic imaging of frozen sections derived from the same tumors. A comparison of all control and treated tumors revealed similar trends in the contributions of lipid-like and collagen-like species in both in vivo and ex vivo measurements; however, when evaluated as a function of time, longitudinal trends in the scores of collagen-like and lipid-like components were not consistent between the two data sets, likely due to sample numbers and differences in sampling depth at which information is obtained. Nevertheless, this study demonstrates the potential of fiber-based Raman spectroscopy for identifying early tumor microenvironmental changes in response to clinical doses of radiation therapy.

Preliminary ESR dating results of fault barite shed new insights into the retrospective history of bedrock fault activities in basaltic regions

The chronology of fault activity in bedrock is critical to constraining and understanding periods of active faulting, assessing seismic hazards, and mitigating the effects of earthquakes. However, because of the lack of suitable materials for dating, the temporal reconstruction of faulting in bedrock remains highly challenging for geologists. In the present study, we determine for the first time the electron spin resonance (ESR) ages of fault barite (BaSO4), which is produced by episodes of intense faulting on basalt bedrock fault surfaces. Three barite samples were obtained from a basalt fault section (27°5′23″N, 100°25′45″E, 1.8 km above sea level) of the Lijiang–Xiaojinhe Fault (LXF), southeastern Tibetan Plateau, for ESR measurements. Similar to marine barite, the ESR spectrum of fault barite shows an electron-type center with g = 2.0037, 2.0034, and 2.0028 attributed to SO3−. The signal intensity systematically increased with increasing gamma-ray dose. Dose rates were calculated using a model based on the location and burial depth of the barite samples, as well as their surrounding bedrock. The three barite samples yield ESR ages of 131 ± 26, 503 ± 61, and 1416 ± 246 ka, respectively, which indicate that the LXF was active during the Early and Middle Pleistocene. The three ESR ages for fault barite from basalt extend the time range of activity of the LXF compared with previous carbonate ESR and radiocarbon dating results. Consequently, we propose that ESR dating of barite is valuable for reconstructing the history of bedrock fault activity. However, given that this investigation represents a preliminary application of the fault-barite ESR method, further study is needed to confirm its usefulness and the accuracy and precision of dating results.