Radiation Micro Research Articles

Influence of snowpack on soil organic carbon decomposition in a northern peatland

Peatlands play a significant role in maintaining the carbon balance and regulating the climate. The turnover of soil organic carbon (SOC) in peatlands is mediated by snowpack, which affects microbial decomposition through its regulation of hydrothermal conditions. However, the impact of snowpack on carbon dynamics in peatlands is not fully understood, particularly in the context of decline in snowpack due to climate warming. To address this issue, an on-site experiment was conducted involving snowpack manipulation (undisturbed and snow removal) to investigate the effects of snowpack on SOC decomposition at depths of 0–30 cm (topsoil) and 30–60 cm (subsoil). Various techniques such as X-ray absorption near-edge structure, synchrotron radiation micro computed tomography technology and microbial metagenomics were utilized to measure SOC content and fractions, pore structure and bacterial community’s structure and function. Results showed that snow removal delayed the start of soil freezing date by 27 days and advanced the start of thawing date by 39 days, increased maximum freezing depth by 27.9 cm and frequency of freeze–thaw cycles, and decreased average temperature of topsoil and subsoil by 1.48 °C and 1.34 °C, respectively. Additionally, snow removal increased SOC content by 8.27 % and 3.19 % and its stability by 53 % and 13.92 % in the topsoil and subsoil, respectively, and decreased microbial decomposition potential functioning by 55.89 % and 5.75 % in both soil layers. The three-dimensional spatial distribution of SOC and soil pores at the micro-scale indicated that snow removal significantly influenced pore structure and microbe feedback loops, thereby affecting SOC decomposition. Notably, snow removal led to an increase in the proportion of micropores by 3.44 % and 4.41 % in the topsoil and subsoil, respectively, suggesting enhanced protection of pore structure and preservation of SOC during decomposition processes. Overall, the findings suggest that snow removal may intensify the response of carbon pools to climate change in peatlands.

Detectability by X-ray micro computed tomography of fatigue initiating void defects in laser powder-bed additively manufactured Ti-6Al-4V coupons

Non-destructive inspection is important for the quality assurance of additively manufactured components. In this study, X-ray micro Computed Tomography (µCT) was assessed for its capabilities and limitations to detect fatigue-initiation porosities in Ti-6Al-4V additively manufactured coupons. Cylindrical coupons were built using laser powder-bed fusion (L-PBF) from three different vendors and four different L-PBF machines that utilized their default process parameters. Using OEM prescribed default process parameters, there was significant variability in the defect distribution between machine to machine and also coupon to coupon that was on the same build plate, primarily due the difference in the internal quality assurance procedures and scan strategies adopted by each vendor. The probability of detection for conventional µCT (cubic voxel size 17.77 µm) was investigated by comparing with what was detected using a Synchrotron Radiation Micro Computed Tomography (SRµCT) at cubic voxel size 5.91 µm. It was found that µCT’s detectability relative to SRµCT was approximately 90% for defect diameters of the circumscribed sphere of 230 µm and above and 100% for diameters of 340 µm and above (12–14 times the voxel size of the µCT scan). The type of defect was a key factor to the detectability of large sized defects (>200 µm in diameter) due to the flatness and elongated shape factors. Fatigue results showed the critical defect √Area at the surface was approximately 100 µm at 500 MPa stress level, where significant scatter in fatigue life was observed. Post-fatigue test fractography identified different types of fatigue initiating defects, of which a ‘flat’ lack-of-fusion type defect was undetectable by either µCT or SRµCT. This type of defect was extremely flat and occupied very little spatial resolution through the build direction which limited the detection by automated threshold-based defect detection algorithms.

The incorporation of chlorine and cosmogenic 36Cl into speleothem carbonate

AbstractCave carbonate mineral deposits (speleothems) contain trace elements that are intensively investigated for their significance as palaeoclimate and environmental proxies. However, chlorine, which is abundant in marine and meteoric waters, has been overlooked as a potential palaeo-proxy, while cosmogenic 36Cl could, in principle, provide a solar irradiance proxy. Here, total Cl concentrations analysed from various speleothems were low (3–14 mg/kg), with variations linked to crystal fabrics. High-resolution synchrotron radiation micro X-ray fluorescence (μ-XRF) trace element mapping showed Cl often associated with Na, Si, and Al. We propose that speleothems incorporate Cl in two fractions: (1) water soluble (e.g., fluid inclusions) and (2) water insoluble and strongly bound (e.g., associated with detrital particulates). However, disparities indicated that alternate unidentified mechanisms for Cl incorporation were present, raising important questions regarding incorporation of many trace elements into speleothems. Our first measurements of 36Cl/Cl ratios in speleothems required large samples due to low Cl concentrations, limiting the potential of 36Cl as a solar irradiance proxy. Critically, our findings highlight a knowledge gap into how Cl and other trace elements are incorporated into speleothems, how the incorporation mechanisms and final elemental concentrations are related to speleothem fabrics, and the significance this may have for how trace elements in speleothems are interpreted as palaeoclimate proxies.

Effect of gadopentetate dimeglumine on bone growth in zebrafish caudal fins

Compared with MR plain scanning, gadolinium (Gd)-enhanced MR scanning can provide more diagnostic information. Gadopentetate dimeglumine is generally used as an MR enhancement contrast agent in some countries. It is a member of linear Gd-based contrast agents (GBCAs) which are considered more likely to release free Gd ions (Gd3+) than macrocyclic GBCAs. Gd3+ is one of the most effective known calcium antagonists, and can compete with calcium ions (Ca2+) in Ca2+-related biological reactions. In this study, animal models of tissue regeneration were established by cutting the caudal fins of zebrafish, and the models were exposed with gadopentetate dimeglumine solution for different immersion times of 1, 3, and 5 min. Three GBCA exposures per week were performed in the first 3 weeks of the follow-up time. Morphological parameters such as regenerative area (RA), bone density, bone thickness and regenerative bone volume (RBV) were quantified using a camera and synchrotron radiation micro CT. RA decreased as total Gd intake increased in both the female group (ρ = −0.784, P < 0.0001) and the male group (ρ = −0.471, P = 0.011). The bone density of the regenerated bone increased after Gd exposure in the treated groups. The morphology of the regenerated bone from the treated groups became shorter and thicker. Our results showed that gadopentetate dimeglumine had osteogenic toxicity in zebrafish.

Violin Varnishes: Microstructure and Nanomechanical Analysis.

The aim of the current work is twofold: to demonstrate the application of in situ non-invasive imaging by portable atomic force microscopy (AFM) on the surfaces of a violin and to integrate compositional and mechanical analysis at the nano scale level on model samples of varnished wood. These samples were prepared according to traditional recipes by an Italian lute-maker family well practised in the art. Samples of oil and spirit-based varnishes on maple wood, naturally and accelerated light aged, were studied. AFM was used to measure the nanomechanical properties of the model samples and established that the spirit-based varnish was stiffer than the oil-based. Synchrotron radiation micro- Fourier Transform Infra-red analysis of the layer structure revealed that stiffer spirit-based varnish showed less penetration into the wood than the oil-based. Further PeakForce Quantitative Nanomechanical Mapping (QNM) demonstrated a difference in adhesion values between the oil- and spirit-based samples.

Assessing the long-term in vivo degradation behavior of magnesium alloys - a high resolution synchrotron radiation micro computed tomography study

Biodegradable magnesium (Mg) implants are emerging as a potential game changer in implant technology in situations where the implant temporarily supports the bone thereby avoiding secondary surgery for implant removal. However, the consequences of the alteration in the degradation rate to bone healing and the localization of degradation and alloying products in the long term remain unknown. In this study, we present the long-term osseointegration of three different biodegradable Mg alloys, Mg-10Gd, Mg-4Y-3RE and Mg-2Ag, which were implanted into rabbit femur for 6 and 9 months. In addition, we have investigated the effect of blood pre-incubation on the in vivo performance of the aforementioned alloys. Using high-resolution synchrotron radiation based micro computed tomography, the bone implant contact (BIC), bone volume fraction (BV/TV) and implant morphology were studied. The elemental traces have been characterized using micro X-ray fluorescence. Qualitative histological evaluation of the surrounding bone was also performed. Matured bone formed around all three implant types and Ca as well as P which represent parts of the degradation layer were in intimate contact with the bone. Blood pre-incubation prior to implantation significantly improved BIC in Mg-2Ag screws at 9 months. Despite different implant degradation morphologies pointing toward different degradation dynamics, Mg-10Gd, Mg-4Y-3RE and Mg-2Ag induced a similar long-term bone response based on our quantified parameters. Importantly, RE elements Gd and Y used in the alloys remained at the implantation site implying that they might be released later on or might persist in the implantation site forever. As the bone formation was not disturbed by their presence, it might be concluded that Gd and Y are non-deleterious. Consequently, we have shown that short and mid-term in vivo evaluations do not fully represent indicators for long-term osseointegration of Mg-based implants.

High-resolution ex vivo analysis of the degradation and osseointegration of Mg-xGd implant screws in 3D

Biodegradable magnesium (Mg) alloys can revolutionize osteosynthesis, because they have mechanical properties similar to those of the bone, and degrade over time, avoiding the need of removal surgery. However, they are not yet routinely applied because their degradation behavior is not fully understood.In this study we have investigated and quantified the degradation and osseointegration behavior of two biodegradable Mg alloys based on gadolinium (Gd) at high resolution.Mg-5Gd and Mg-10Gd screws were inserted in rat tibia for 4, 8 and 12 weeks. Afterward, the degradation rate and degradation homogeneity, as well as bone-to-implant interface, were studied with synchrotron radiation micro computed tomography and histology. Titanium (Ti) and polyether ether ketone (PEEK) were used as controls material to evaluate osseointegration.Our results showed that Mg-5Gd degraded faster and less homogeneously than Mg-10Gd. Both alloys gradually form a stable degradation layer at the interface and were surrounded by new bone tissue. The results were correlated to in vitro data obtained from the same material and shape. The average bone-to-implant contact of the Mg-xGd implants was comparable to that of Ti and higher than for PEEK. The results suggest that both Mg-xGd alloys are suitable as materials for bone implants.

Effect of Exercise Intensity on the Healing of the Bone-Tendon Interface: A Mouse Rotator Cuff Injury Model Study

Background: Injuries at the bone-tendon interface (BTI) are common findings in clinical practice. Rehabilitation procedures after BTI surgery are important but are controversial. Purpose: To investigate the effects of different exercise intensities on BTI healing by means of an established mouse rotator cuff injury model. Study Design: Controlled laboratory study. Methods: A total of 150 specific pathogen free male C57BL/6 mice, with supraspinatus insertion injury, were randomly assigned to 1 of 5 groups according to postoperative rehabilitation of different exercise intensities: (1) control group, (2) low-intensity exercise group, (3) moderate-intensity exercise group, (4) high-intensity exercise group, and (5) increasing-intensity exercise group (IG). The specimens were harvested 4 or 8 weeks postoperatively for microarchitectural, histological, molecular biological, and mechanical evaluations. Results: Histological test results showed that the degrees of tissue fusion and polysaccharide protein distribution at the healing interface at 4 and 8 weeks after surgery were significantly better in the IG than in the other 4 groups. Synchrotron radiation micro–computed tomography showed that the quantity of subchondral bone at the enthesis (bone volume/total volume fraction, trabecular thickness, trabecular number) was higher and trabecular separation was lower in the IG than in the other 4 groups. Quantitative reverse transcription polymerase chain reaction (qRT-PCR) analysis revealed that the healing interface in the IG expressed more transcription factors, such as sox 9, runx 2, and scleraxis, than the interfaces in the other groups. Although no significant difference was seen in the cross-sectional area between the groups at postoperative weeks 4 and 8 (P > .05), the tensile load, ultimate strength, and stiffness of the specimens in the IG were significantly better than those in the other 4 groups (P < .05). Conclusion: The rehabilitation program with increasing-intensity exercise was beneficial for BTI healing. Clinical Relevance: The results of this study provide evidence supporting the use of a simple and progressive exercise rehabilitation program after rotator cuff surgery.

Micro-distribution of arsenic and polycyclic aromatic hydrocarbons and their interaction in Pteris vittata L.

Interactive effects of inorganic arsenic (As) species and polycyclic aromatic hydrocarbons (PAHs) on their uptake, accumulation and translocation in the hyperaccumulator Pteris vittata L. (P. vittata) were studied hydroponically. The presence of PAHs hindered As uptake and acropetal translocation by P. vittata, decreasing As concentrations by 29.8%–54.5% in pinnae, regardless of the initial As speciation. The inhibitive effect of PAHs was 1.6–8.7 times greater for arsenite [As(III)] than for arsenate [As(V)]. Similarly, inorganic As inhibited the uptake of fluorene (FLU) and benzo[a]pyrene (BaP) by P. vittata roots by 0.4%–21.7% and by 33.1%–69.7%, respectively. Interestingly, coexposure to As and PAHs slightly enhanced the translocation of PAHs by P. vittata with their concentrations increased 0.3 to 0.8 times in shoots, except for the As(III)+BaP treatment. The antagonistic interaction between As and PAHs uptake is likely caused by competitive inhibition or oxidative stress injury. By using synchrotron radiation micro X-ray fluorescence imaging, high concentrations of As were found distributed throughout the microstructures far from main vein of the pinnae when coexposed with PAHs, the opposite of what was observed with exposure to As only. PAHs could also significantly inhibit the accumulation and distribution of As in vascular bundles in rachis treated with As(III). The results of two-photon laser scanning confocal microscopy revealed that PAHs were mainly distributed in the vascular cylinder, epidermal cells, vascular bundles, epidermis and vein tissues, and this was independent of As speciation and treatment. This work offers new positive evidence for the interaction between As and PAHs in P. vittata, presents new information on the underlying mechanisms for interactions of As and PAHs affecting their uptake and translocation within P. vittata L., and provides direction for future research on the mechanisms of PAHs uptake by plants.

Deep learning based solar radiation micro forecast by fusion of infrared cloud images and radiation data

Solar irradiance forecasting has been gaining paramount importance in recent years due to its impact on power grids. However, solar energy harvesting over shorter periods also brings new challenges due to its intermittent and uncertain attributes. Hence, accurate forecasting has become an indispensable aspect of the effective management of power system operations. The existing models focus on using only time-series data for solar radiation forecasting. But during cloudy time instances, it fails to quickly capture the nonlinear Spatio-temporal variations in the data for shorter periods. To bridge this gap, in this paper, a multi-modal fusion network is developed for studying solar irradiance micro forecasts by using both infrared images and past solar irradiance data. Here both spatial and temporal information is extracted parallelly and fused using a fully connected neural network. The solar forecasts of the proposed methods are evaluated against benchmark models in terms of Mean Absolute Percentage Error (MAPE) and other qualitative measures. The experimental results illustrate that the multi-modal fusion networks outperform the existing methods while predicting solar irradiance for cloudy days as well as mixed days (both cloudy and sunny days). Hence a transfer learning-based classifier with 99.23% accuracy is developed to categorize the cloudy days from sunny days. In the case of higher horizon forecasts, the proposed models show the optimum trade-off between performance and test time. Moreover, the Multiple Image Convolutional Long Short Term Memory Fusion Network (MICNN-L) shows a 46.42% improvement in MAPE whereas the Convolutional Long Short Term Memory Fusion Network (CNN-L) has a 42.02% increase when compared to the benchmark machine learning and deep learning models.

Archive data on climate changes and seismic events in glacial clays of Lake Kucherla (Altai region, Russia)

Core samples taken from the bottom sediments of the glacial Lake Kucherla (Gorny Altai, Russia) clearly show annual layers represented by glacial clays. In our study, age-depth modeling is based the varve chronology and Cs-137, Pb-210 and C-14 isotope data. Our model is a highly accurate and reliable demonstration of the annual sedimentation history within the past 1400 years. The time series of geochemical indicators of climate change were obtained by synchrotron radiation micro X-ray fluorescence (SR- μ XRF) core scanning. Instrumental meteorological observations from 1940 to 2016 were used to construct transfer functions for the average annual temperatures and atmospheric precipitation amounts. A geochemical trace of a catastrophic seismic event, the Mongolian earthquake of 1761, was found in the cross-section of the bottom sediments.

Synchrotron radiation micro X-Ray Fluorescence (SR-μXRF) elemental mapping of ancient hair: Metals and health at 3rd millennium BCE Shahr-i Sokhta, Iran

Only a handful of studies using synchrotron radiation enabled approaches to ancient human hair have been undertaken to date, few studies explore metal element distribution within ancient hair, and none Cu in particular. This paper shows how key archaeological questions, such as effects of intensive metal and craft work on human health, can be investigated using synchrotron radiation micro X-Ray Fluorescence (SR-μXRF) in exploring biogenic versus diagenetic/environmental uptake of metals, and copper in particular, in ancient human hair. The ID21 scanning X-ray microscope optimized for 2D μXRF (elemental maps) was used at the ESRF (European Synchrotron Radiation Facility) to obtain detailed elemental maps, including Cu, in ancient hair sections (10 μm) of eight individuals (n = 8), as well as modern hair controls (n = 2). Differentiation in the levels of Cu were discovered between different skeletal individuals from the site of Shahr-i Sokhta, a 3rd millennium BCE large urban site with intensive metalwork and other craft work activities in ancient Iran. In particular, hair of a young female showed elevated levels of Cu, with highest values distributed within the cortex. This distribution of elevated levels of Cu, together with contextual data, points to biogenic, rather than diagenetic/environmental source for the uptake of Cu.

Revealing Silver Nanoparticle Uptake by Macrophages Using SR-μXRF and LA-ICP-MS.

To better study the impact of nanoparticles on both in vitro and in vivo models, tissue distribution and cellular doses need to be described more closely. Here silver nanoparticles were visualized in alveolar macrophages by means of synchrotron radiation micro X-ray fluorescence spectroscopy (SR-μXRF) with high spatial resolution of 3 × 3 μm2. For the spatial allocation of silver signals to cells and tissue structures, additional elemental labeling was carried out by staining with eosin, which binds to protein and can be detected as bromine signal with SR-μXRF. The method was compatible with immunostaining of macrophage antigens. We found that the silver distribution obtained with SR-μXRF was largely congruent with distribution maps from a subsequent laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) of the same tissue sites. The study shows a predominant, though not exclusive uptake of silver into alveolar macrophages in the rat lung, which can be modeled by a similar uptake in cultured alveolar macrophages. Advantages and limitations of the different strategies for measuring nanoparticle uptake at the single cell level are discussed.

Qualitative and Semiquantitative Determination of Bromine in Hybrid Hydroxyurethanes-Poly(dimethylsiloxane) Films Containing Phosphotungstates ([PW&lt;sub&gt;12&lt;/sub&gt;O&lt;sub&gt;40&lt;/sub&gt;]&lt;sup&gt;3-&lt;/sup&gt;)

In this study, the complex hybrid materials based on hybrid poly(dimethylsiloxane)-derived hydroxyurethanes films (PDMSUr-PWA) containing phosphotungstic acid (H₃PW₁₂O₄₀/PWA) and Bromine were analyzed by laboratory XRF (EDXRF, WDXRF), Synchrotron Radiation Micro X-ray Fluorescence (SR-μXRF), and Volumetric analysis, in order to correlate the distribution patterns and composition of Bromine with their respective properties and potential applications. Recently, the characterization and analysis of PDMSUr-PWA films (without consider Bromine) was reported in order to correlate structure, compositions and properties. SR-μXRF maps provide indicatives of the possible inter-elemental interactions Bromine-Silicon-Tungsten. There is segregation of Bromine at surface and through the thickness of PDMSUr-PWA films. These films possess hydrophobicity and non-hygroscopic properties, which makes potential candidates for high-performance adhesives, corrosion-resistant coatings of steel and titanium alloys surfaces in different media. The presence of Bromine (element provided from tetraethylammonium bromide in previous steps of elaboration of PDMSUr-PWA films) could contribute with their corresponding adhesive, thermal-insulator, and anti-corrosive properties. Functional materials as PDMSUr-PWA films present easy processing, excellent toughness and durability. Nowadays, Polyurethane (PU) coatings are very useful in many sectors due to their excellent mechanical properties. Nonetheless, one limitation is their thermal stability, which can be improved by insertion of poly(dimethylsiloxane) (PDMS) segments. The interesting properties of PDMS are of significance for applications as adhesives and at the aerospace industry. The films containing 1%, 35%, 40-50% PWA are candidates as anticorrosive coatings and as inert materials under the presence of polar chemical reagents, based on the significant Bromine presence at surface. The films containing 25% and 55% PWA would be suitable for thermal insulators, based on the significant Bromine presence at thickness. PDMSUr-PWA films can constitute systems for the storage of energy based on the synergy of their potential applications as Proton exchange membrane fuel cells (PEMFCs) and also as H₂-Br₂ multiple micro-fuel cells. PEMFCs have great attention in scientific and industrial fields based on energetic and environmental aspects mainly. PEMFCs based on PDMSUr-PWA films could exhibit high chemical and mechanical stabilities. The hydrogen bromine (H₂-Br₂) electrochemical systems constitute promising candidates as generation and storage devices of energy due to their high energy capacities and conversion efficiencies, as also their low costs. More in depth studies are necessary in order to analyze the different chemical forms of Bromine present (atomic, ionic and/or molecular) in the three-dimensional network constituted by silicates and phosphotungstates, as also the characterization of their local chemical and electrochemical environment.

Testing Contrast Agents to Improve Micro Computerized Tomography (μCT) for Spatial Location of Organic Matter and Biological Material in Soil

Soil carbon is essential for soil and ecosystem functioning. Its turnover and storage in soil are multifaceted processes that involve microbial activity in complex physical matrices. Biological litter, which include plants, animals and microorganisms, is decomposed in soil stimulating soil biota (archaea, bacteria, fungi, protists and animals) activity and yielding soil organic matter (SOM). Such decomposition processes are influenced by local physico-chemical characteristics including the spatial distribution of aggregates and pores. More refined analytical tools are needed to better understand these processes, especially considering the spatial 3D structure of soil matrices. Using synchrotron radiation (X-ray) micro computerized tomography (SR-µCT), we tested different contrast agents (staining methods) based on silver (Ag), eosin (Br based) and liquid and gaseous iodine (I) in order to spatially image biological material and SOM in soil samples. We also performed K-edge SR-µCT for the Ag and I2 treatments and conventional µCT for additional soil samples applying the I2 treatment. Our results indicated that I2 was the most efficient contrast method for SR-µCT imaging of soil samples. I2 qualitatively improved the images, but mainly, by using the K-edge SR-µCT, this method provided a powerful tool to determine the spatial location of SOM. We acknowledge that the use of SR-µCT is an expensive technique to study soil samples, which comes with bottlenecks in terms of access to facilities and measurement time. Nevertheless, we show that the I2 treatment improved soil images also using standard µCT. In conventional µCT the I2 treatment improved the visualization of biological material and consequently improved the qualitative analysis of fine plants roots and micro-fauna (Collembola). This improvement may have a positive implication in soil biology, by improving a non-destructive method to detect fungi (SR-µCT), soil fauna (conventional µCT) and roots in undisturbed soil samples. An unexpected finding was that the I2 treatment also stained the plastic sample containers (nylon and polyimide), indicating the potential for the I2 staining procedure to be applied for the detection of plastic pollution in soil samples.

Analysis of nickel distribution by synchrotron radiation X-ray fluorescence in nickel-induced early- and late-phase allergic contact dermatitis in Hartley guinea pigs.

Background:Nickel-induced allergic contact dermatitis (Ni-ACD) is a global health problem. More detailed knowledge on the skin uptake of haptens is required. This study aimed to investigate the penetration process and distribution of nickel in skin tissues with late phase and early phase of Ni-ACD to understand the mechanisms of metal allergy.Methods:Forty Hartley guinea pigs were divided into four groups according to the NiSO4 sensitizing concentration and the NiSO4 challenged concentration: the 5% NiSO4-group, 5% to 10% (sensitization-challenge; late phase group); 10% NiSO4-group, 10% to 10% (sensitization-challenge; early-phase group); and the positive and negative controls. Pathological biopsies were performed on each group. The depth profile of nickel element concentration in the skin of guinea pigs was detected by synchrotron radiation micro X-ray fluorescence spectroscopy (SR-μ-XRF) and micro X-ray absorption near-edge spectroscopy (μ-XANES).Results:In each section, the nickel element concentration in both the 5% NiSO4-group and 10% NiSO4-group was significantly higher than that in the negative control group. In the upper 300-μm section of skin for the early phase group, the nickel element concentration was significantly higher than that in the lower section of skin. In deeper sections (>200 μm) of skin, the concentration of nickel in the early phase group was approximately equal to that in the late phase group. The curve of the late phase group was flat, which means that the nickel element concentration was distributed uniformly by SR-μ-XRF. According to the XANES data for the 10% NiSO4 metal salt solution, structural changes occurred in the skin model sample, indicating that nickel was not present in the Ni2+ aqueous ionic state but in the nickel-binding protein.Conclusions:This study showed that the distribution of the nickel element concentration in ACD skin tissue was different between the early phase and late phase groups. The nickel element was not present in the Ni2+ aqueous ionic state but bound with certain proteins to form a complex in the stratum corneum in ACD model tissue.

SR micro-XRF to study Pb diffusion using a one-dimensional geometric model in leaves of Brassica napus for phytoremediation

The purpose of phytoremediation is the removal of contaminants by plants that grow in soils with high levels of specific contamination. The technological implementation of lead phytoremediation depends on the understanding of tolerance and growth phenomena of the plant in contaminated soil, uptake and translocation of this element and its accumulation in aerial foliage of the plant. This work provides results about diffusive transfer of lead across the xylem towards leaf blade (or lamina) of Brassica napus using a 1-dimension model that assumes Fick's Second Law. It uses mapping data of Pb concentrations measured by synchrotron radiation micro x-ray fluorescence in order to calculate the diffusion coefficient in soft tissue of leaves. The diffusion equation is solved for a flat leaf geometric model and the solution is fitted to experimental values of Pb concentrations of equivalent leaves, harvested from the same plant in progressive times of its growing cycle. The results of the diffusion coefficient were calculated in a zone (∼600 μm) outside the leaf xylem, where the Pb concentration profile determines a well-defined gradient. These results are original and provide a contribution to understand the dynamics of Pb retention in leaves.

Effect of Low-Intensity Pulsed Ultrasound After Autologous Adipose-Derived Stromal Cell Transplantation for Bone-Tendon Healing in a Rabbit Model

Background: Low-intensity pulsed ultrasound (LIPUS), as a safe biophysiotherapy, can enhance bone-tendon (B-T) healing in vivo and induce osteogenic or chondrogenic differentiation of mesenchymal stromal cells in vitro. This study aimed to determine whether LIPUS can improve the efficacy of transplanted mesenchymal stromal cells on B-T healing. Hypothesis: LIPUS can induce lineage-specific differentiation of transplanted adipose-derived stromal cells (ASCs) at the B-T healing site, thus resulting in superior healing quality when compared with LIPUS or ASCs alone. Study Design: Controlled laboratory study. Methods: A total of 112 mature rabbits with partial patellectomy in the hindlimb were randomly assigned into mock sonication without ASCs (control), ultrasonication without ASCs (LIPUS), mock sonication with ASCs (ASCs), and ultrasonication with ASCs (LIPUS + ASCs). The treatment time of the mock sonication or ultrasonication was 20 minutes per day. Autologous ASCs were transplanted to the healing site by fibrin glue during the operation, and LIPUS was delivered daily starting at postoperative day 3 until euthanasia. The patella–patellar tendon junctions were postoperatively harvested at 8 and 16 weeks for radiological, histological, and mechanical evaluations. Additionally, 9 animals were used for ASC tracking with mCherry protein. Results: Radiologically, there was more new bone formation and remodeling in the LIPUS + ASCs group as compared with the other groups. Synchrotron radiation micro–computed tomography showed that the LIPUS + ASCs group significantly increased bone volume fraction, trabecular thickness, and trabecular number at the healing site as compared with the other groups at postoperative 8 weeks (P < .05 for all). Histologically, immunohistochemical staining confirmed that the transplanted mCherry-ASCs can differentiate into osteoblasts and fibrochondrocytic-like cells. Meanwhile, as compared with the other groups, the LIPUS + ASCs group showed more formation and maturity of the fibrocartilage layer and new bone at postoperative weeks 8 and 16 (P < .05 for all). Biomechanically, the LIPUS + ASCs group showed significantly higher failure load and stiffness versus the other groups at postoperative weeks 8 and 16 (P < .05 for all). Conclusion: Autologous ASC transplantation stimulated with LIPUS can result in superior B-T healing quality when compared with LIPUS or ASCs alone. Clinical Relevance: This study demonstrates the effectiveness of using ASC transplantation stimulated with LIPUS for B-T healing and provides a foundation for future clinical studies.

Effect of EDTA and NTA on cadmium distribution and translocation in Pennisetum purpureum Schum cv. Mott.

The primary objective of this research was to investigate the cadmium (Cd) distribution in Pennisetum purpurem (Napier grass) in the presence of 30mg/L of Cd and different types and concentrations of chelating agents (ethylenediaminetetraacetic acid disodium dihydrate (EDTA), nitrilotriacetic acid (NTA), and EDTA-NTA mixtures). Plant samples were collected every 15d during a 105-d experimental period. Accumulation of Cd in each part of the plant was determined using atomic absorption spectrometer (AAS), and the distribution of Cd was determined by laser ablation inductively coupled plasma mass spectrometer (LA-ICP-MS) and synchrotron radiation micro X-ray fluorescence (SR-micro-XRF). The highest concentrations of Cd accumulation of 889 ± 53mgkg-1 in the underground part (roots) and 265 ± 26mgkg-1 in the aboveground part (stems and leaves) in the presence of 1:1M ratio of Cd:EDTA after 30d of exposure were observed. Plants grown in the presence of either NTA or EDTA-NTA mixtures showed significant lower Cd accumulation levels. The LA-ICP-MS analysis showed that Cd was primarily accumulated in the aboveground part (stems and leaves), especially in the xylem and intercalary meristem. In addition, translocation factor was very low. Thus, P. purpurem could be considered as a candidate plant for cadmium phytostabilization.

Investigation of calcium and zinc distribution in rabbit patella-patellar tendon interface using synchrotron radiation micro X-ray fluorescence technique

Objective The unique distributions and maps of calcium and zinc at the regions of interest in patella-patellar tendon interface (PPTI) were detected by synchrotron radiation micro X-ray fluorescence (SR-μXRF). Methods Healthy New Zealand rabbits were used in this experiment. Five harvested PPTI samples were cut along the sagittal plane of the PPTI by a microtome. Sections of PPTI were then scanned by SR-μXRF at BL15U1 of shanghai synchrotron radiation facility (SSRF) in China. Then the samples were used for histological staining with hematoxylin and eosin (HE) and Van-Gieson. Results Histological staining showed that the thickness of calcified fibrocartilage in PPTI was (163.00±42.00) μm; The distributions and characterization of calcium and zinc of PPTI were successfully obtained via the SR-μXRF. The maximum calcium content [93 853 cps, (28.00±9.05) times of that of patellar tendon] was found in the transitional zone of calcified fibrocartilage region and the patella. A significant accumulation of zinc [10 100 cps, (3.20±0.65) times of that of patellar tendon] was exhibited in the transition area of tidemark. The maximum content of zinc was (8.70±3.20) times of that of calcium. The distribution distance between the maximum content of calcium and zinc was (135.00±16.00) μm, which was consistent with histological staining (r2=0.935). Conclusion SR-μXRF served as a high-precision and high-resolution instrument to qualitatively assess the distributions of calcium and zinc in the PPTI, which provides a new insight for the study of bone tendon interface repair. Key words: Synchrotron radiation-based micro X-ray fluorescence analysis; Calcium; Zinc; Bone tendon interface