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Microwave remote sensing can provide effective monitoring of landscape FT dynamics. Its sensitivity to surface permittivity, which is predominantly influenced by the phases of water, can be used to measure landscape freeze/thaw state information. The technique of Interferometric Synthetic Aperture Radar (InSAR) enables to map the ground movement through the use of Synthetic Aperture Radar (SAR). Compared to optical imagery, microwave data has advantages that it would not be affected by cloud cover, smoke or daylight and exhibits useful penetration depths of soil and vegetation. Both active and passive microwave remote sensing with different wavelengths have shown their principal capacity in many studies and have complementary advantages to each other. While many passive sensors (such as SMAP and SMOS) are providing observations with high temporal resolution and good worldwide coverage at the deca-kilometer scale, there are a series of active sensors providing observations with worse temporal resolution but much better spatial resolution at the scale from a few meters to a few deca-meters, for example, the Sentinel-1 mission from the European Space Agency (ESA) with 5 x 5 m spatial resolution and 6-12 days repeat cycle. Hence, the combined use of different microwave data can be expected further to promote the monitoring of permafrost-related phenomena and permafrost-dominated landscapes.An assumption of near-linear relation between the measurements from the passive and active sensors has been used in NASA’s Soil Moisture Active Passive (SMAP) active-passive baseline algorithm for downscaling coarse-resolution radiometer brightness temperature (TB) using high-resolution radar backscatter (σ 0). Recent research proved that a good linear relationship could be found at a global scale (Zeng et al., 2021). However, the relation is significantly affected by environmental factors, for example, the density of vegetation cover. Based on the findings, we attempt to explore the possibility of merging microwave remote-sensing data from different platforms in this work. We are committed to exploring suitable data sources for merging, as well as the possibility of taking environmental factors into consideration. The capacity and limitation of the merging process will be discussed.

In the terrestrial cryosphere, freeze/thaw (FT) state transition plays an important and measurable role for climatic, hydrological, ecological, and biogeochemical processes in permafrost landscapes.Satellite active and passive microwave remote sensing has shown its principal capacity to provide effective monitoring of landscape FT dynamics. Many algorithms have been developed and evaluated over time in this scope. With the advancement of data science and artificial intelligence methods, the potential of better understanding the cryosphere is emerging.This work is dedicated to exploring an effective approach to retrieve FT state based on microwave remote sensing data using machine learning methods, which is expected to fill in some hidden blind spots in the deterministic algorithms. Time series of remote sensing data will be created as training data. In the initial stage, the work aims to test the feasibility and establish the basic neural network based on fewer training factors. In the advanced stage, we will improve the model in terms of structure, such as adding more complex dense layers and testing optimizers, and in terms of discipline, such as introducing more influencing factors for training. Related parameters, for example, land cover types, will be included in the analysis to improve the method and understanding of FT-related processes.

Electrically tunable optical properties in materials are desirable for many applications ranging from displays to lasing and optical communication. In most two-dimensional thin films and other quan...

The risk of water erosion on the Tibetan Plateau (TP), a typical fragile ecological area, is increasing with climate change. Rainfall erosivity maps are useful for understanding the spatiotemporal patterns of rainfall erosivity and identifying vulnerable regions. This study generated a gridded annual rainfall erosivity dataset of the TP for 1950–2020 using a new approach based on 1-min precipitation observations at 1787 weather stations and 0.25° hourly European Center for Medium-Range Weather Forecasts Reanalysis 5 (ERA5) precipitation data. We conclude that ERA5 is generally useful for mapping annual rainfall erosivity on the TP, considering the high correlation coefficient and consistent spatiotemporal patterns between the ERA5-based and observed annual rainfall erosivity. In addition, obvious underestimation of the ERA5-based annual rainfall erosivity was found. After correction by a multiplier factor map, the annual rainfall erosivity values for 2013–2020 are in good agreement with the observed values in terms of the correction coefficient and probability density. Finally, a new annual rainfall erosivity dataset for 1950–2020 was produced after the ERA5-based annual rainfall erosivity values were corrected. We found that the area-averaged mean annual rainfall erosivity on the TP is 307 MJ·mm·ha−1·h−1 and tends to decrease from southeast to northwest. Key regions with large rainfall erosivity potential are concentrated in the Bomi–West Sichuan and Dawang–Chayu areas. This new annual rainfall erosivity dataset could extend our knowledge of rainfall erosivity patterns and provide fundamental data for quantifying soil erosion in the TP.

Investigation of microbial community structures is critical for situ-remediation of heavy metal contaminated soils. For this purpose, we used high-throughput 18S rRNA sequencing method to analyze soil fungal communities in the Shanping village (SPC) and Yanzibian (YZB) tailings situated in northwestern China. The relationships of the fungal community and the environmental factors, including heavy metals and soil chemical properties were analyzed. The results showed that the fungal community richness and diversity in the soils were both trending as control soil > contaminated soil. The compositions and relative abundances of the fungal populations in the two tailings were different, however the dominant fungal phyla of which were almost the same, mainly including Ascomycota, Basidiomycota, Calcarisporillomycota, Mortierellomycota, and Rozellomycota. Further, the Canonical correlation analysis and spearman correlation analyses revealed that Cd, Pb, Cu, Zn, Cr, TP, NO3−-N, TN, and/or pH were predominantly positive correlation factors for the most abundant fungal phyla Ascomycota and Basidiomycota. Together, we have sorted out certain fungal species, such as s_unclassified_p_Ascomycota, s_unclassified_c_Sordariomycetes, s_Talaromyces_solicola, and s_Cutaneotrichosporon_curvatus, which are probably tolerant to heavy metals in these specific tailing soils. Overall, our results have provided an initial perspective of the fugal community variations of these specific tailing ponds.

We evaluated the variations of bacterial communities in six heavy metal contaminated soils sampled from Yanzi Bian (YZB) and Shanping Cun (SPC) tailings located in northwestern China. Statistical analysis showed that both the heavy metals and soil chemical properties could affect the structure and diversity of the bacterial communities in the tailing soils. Cd, Cu, Zn, Cr, Pb, pH, SOM (soil organic matters), TP (total phosphorus) and TN (total nitrogen) were the main driving factors of the bacterial community variations. As a consequence, the relative abundances of certain bacterial phyla including Proteobacteria, Chloroflexi, Firmicutes, Nitrospirota and Bacteroidota were significantly increased in the tailing soils. Further, we found that the abundance increasement of these phyla were mainly contributed by certain species, such as s__unclassified_g__Thiobacillus (Proteobacteria), s__unclassified_g__Sulfobacillus (Firmicutes) and Leptospirillum ferriphilum (Nitrospirota). Thus, these species were considered to be strongly heavy metal tolerant. Together, our findings will provide a useful insight for further bioremediations of these contaminated areas.

Investigations of the impact of heavy metals on microbial community structure are crucial for bioremediation of the contaminated sites. To this end, high-throughput 16S rRNA sequencing was performed to assess the variations of bacterial communities in 6 heavy metal-contaminated soils sampled from Liujiaping (LJP) and Shanping (SP) lead–zinc tailings situated in northwestern China. Compared with those of the farmland soil (NT), the heavy metal levels and chemical properties of the tailing soils were significantly different. Consistently, the bacterial community structures have been changed, displaying as the bacterial richness and diversity in the tailing soils were either increased or decreased, i.e., trending as SP > NT > LJP. The relative abundances of certain bacterial phyla mainly including Actinobacteriota, Acidobacteriota, Cyanobacteria, Gemmatimonadota, and Bacteroidota were significantly increased in certain SP and/or LJP soils. Further, the relative abundances of Actinobacteriota and Bacteroidota were positively correlated with Cd, TP, TK, SOM, TN, and pH. The abundance of Cyanobacteria was significantly upregulated by Cu, Zn, and TP. Acidobacteriota was notably positively correlated with Cr, Pb, and NO3−_N. On the contrary, the relative abundance of Chloroflexi was negatively correlated with all the environmental parameters, especially with Cd, NO3−_N, TP, SOM, and TN. Together, our results implied that the heavy metals and chemical properties were both driving forces of the variations of the bacterial community structures in the tailing soils. Overall, we have successfully identified certain bacterial species such as s__unclassified_g__Sulfurifustis, s__unclassified_f__Rhodanobacteraceae, s__unclassified_g__Conexibacter, s__unclassified_g__norank_f__norank_o__Gaiellales, and s__unclassified_g__Blastococcus which were probably heavy metal-tolerant in these specific tailing soils, and this will provide a theoretical support for further bioremediations.

Physical models used to forecast the temporal occurrence of rainfall-induced shallow landslides are based on deterministic laws. Owing to the existing measuring technology and our knowledge of the physical laws controlling landslide initiation, model uncertainties are due to an inability to accurately quantify the model input parameters and rainfall forcing data. An uncertainty analysis of slope instability prediction provides a rationale for refining the geotechnical models. The Transient Rainfall Infiltration and Grid-based Regional Slope Stability-Probabilistic (TRIGRS-P) model adopts a probabilistic approach to compute the changes in the Factor of Safety (FS) due to rainfall infiltration. Slope Infiltration Distributed Equilibrium (SLIDE) is a simplified physical model for landslide prediction. The new code (SLIDE-P) is also modified by adopting the same probabilistic approach to allow values of the SLIDE model input parameters to be sampled randomly. This study examines the relative importance of rainfall variability and the uncertainty in the other variables that determine slope stability. The precipitation data from weather stations, China Meteorological Administration Land Assimilation System 2.0 (CLDAS2.0), China Meteorological Forcing Data set precipitation (CMFD), and China geological hazard bulletin are used to drive TRIGRS, SLIDE, TRIGRS-P and SLIDE-P models. The TRIGRS-P and SLIDE-P models are used to generate the input samples and to calculate the values of FS. The outputs of several model runs with varied input parameters and rainfall forcings are analyzed statistically. A comparison suggests that there are significant differences in the simulations of the TRIGRS-P and SLIDE-P models. Although different precipitation data sets are used, the simulation results of TRIGRS-P are more concentrated. This study can inform the potential use of numerical models to forecast the spatial and temporal occurrence of regional rainfall-induced shallow landslides.

LiFePO4 is one of the most promising cathode materials for lithium ion batteries. To investigate the role of the cation in the ionothermal synthesis of LiFePO4, three imidazolium-based ionic liquid...

This paper compares the accuracy of the integral equation method and the multiple scales method in solving the amplitude equation of multi degree of freedom nonlinear vibration systems. We consider three examples: a two-degree-of-freedom stainless-steel beam system controlled by a saturation controller, a three-degree-of-freedom rotating compressor blade model and a four-degree-of-freedom horizontally supported Jeffcott-rotor system controlled by a PPF controller. The amplitude equations are obtained by applying the integral equation method and the method of multiple scales. The stability analysis is achieved based on the Floquet theory together with Routh–Hurwitz criterion. Furthermore, we modified the iterative procedure of the integral equation method to make the analytic approximate solution more accurate. Finally, the analyses show that in most cases, the analytical solutions obtained by the integral equation method are more excellent agreement with the numerical solutions than the most commonly used method of multiple scales. Therefore, the integral equation method is worth popularizing to obtain the approximate analytical solutions of the multi-degree-of-freedom nonlinear vibration system.

Studying the daily evolution of turbulent fluxes modulated by snowfall over the Tibetan Plateau (TP) is of great importance to understand the features of the change in the TP heat source/sink and its contribution to Asian atmospheric circulation and weather processes. However, the lack of data over the TP restricts the detailed studies. Based on observations from four sites of the Third TP Atmospheric Scientific Experiment, the process of surface energy balance impacted by snow is investigated. The results show that the surface albedo largely increases on the first day of snow and then slowly decreases. Correspondingly, the sensible heat (H) flux sharply decreases after snow and then gradually recovers to the original level during the following approximately 10 days. The latent heat (LE) flux becomes more active and stronger after snowfall and persists for a longer period than H, since the soil moisture may still contribute to a high LE after snowmelt. As the synergistic result of H and LE modulated by snow, the surface turbulent heating (i.e., the sum H and LE) of the TP decreases at the early period of snow events and then even enhances to a higher level after the snowmelt than before snow. Comparison analyses reveal that the impact of snow on the H and LE over the TP is much stronger than over similar latitude low‐altitude regions in North America and Europe, which may be partly attributed to the larger and more drastic change of the surface net solar radiation associated with snow processes in the TP. The ERA5 and CFS reanalysis data sets fail to reproduce the modulation of snow on the heat fluxes, which suggests that the physical schemes of the models should be further improved based on the observational analyses over TP. This study may help further understand the detailed physical processes of modulation of snow events on Asian weather processes during winter and is also conducive to the improvement of surface parameterization schemes of models.

In this paper, two modified nonlinear saturation-based controllers and negative velocity feedback controllers are integrated to suppress the horizontal and vertical vibrations of a horizontally supported Jeffcott-rotor system at primary resonance excitation and the presence of 1:1 and 1:2 internal resonances. The second order approximations and the amplitude equations are obtained by applying the integral equation method to analyze the nonlinear behavior of this model. The stability of the steady-state solutions is ascertained based on the Floquet theory. The necessity of adding a negative velocity feedback to the main system is stated. The effects of different control parameters on the frequency-response curves and the force-response curves are investigated. Time histories of the whole system are included to show the response with and without control. It is shown that the saturation-based controller can reduce the system response to almost zero and the negative velocity feedback can suppress the transient vibrations and prevent the main system having the large amplitude vibration. The analyses show that analytical solutions are in excellent agreement with the numerical simulations. Finally, a comparison with previously published works is included.

In the terrestrial cryosphere, freeze/thaw (FT) state transitions play an important and measurable role for climatic, hydrological, ecological, and biogeochemical processes in permafrost landscapes. Satellite active and passive microwave remote sensing has shown its principal capacity to provide effective monitoring of landscape FT dynamics. Sentinel-1 continues to deliver high-resolution microwave remote sensing than ever before and has therefore a large potential of usage for monitoring. In light of this, the capability and responses of its radar backscatter to landscape FT processes in different surface soil depths should be examined to provide a thorough grounding for a robust application of the F/T retrieval algorithm.This study presents a seasonal threshold approach, which examines the time series progression of remote sensing measurements relative to signatures acquired during seasonal reference frozen and thawed states. It is developed to estimate the FT-state from the Sentinel 1 database and applied and evaluated for the region of Eastern Nunavik (Québec, Canada). In this course, the FT state transitions derived from Sentinel 1 data are compared to temporally overlapping situ measurements of soil moisture from different depths within the top 20cm soil. This work allows to explore differences in the sensitivity of the Sentinel 1 at different surface soil depths in higher detail; this information is used to examine the penetration performance of the Sentinel 1 under different conditions of permafrost and permafrost-dominated landscapes.This work is dedicated to providing more accurate data to capture the spatio-temporal heterogeneity of freeze/thaw transitions. As Sentinel-1 continues to deliver high-quality information, the provided threshold algorithm delivers an extended time series to analyze FT-states and improve our understanding of related processes in permafrost landscapes.

Ochratoxin A (OTA) is a common environmental pollutant found in a variety of foods and grains, and excessive OTA consumption causes serious global health effects on animals and humans. Astaxanthin (AST) is a natural carotenoid that has anti-inflammatory, antiapoptotic, immunomodulatory, antitumor, antidiabetes, and other biological activities. The present study is aimed at investigating the effects of AST on OTA-induced cecum injury and its mechanism of action. Eighty C57 mice were randomly divided into four groups, including the control group, OTA group (5 mg/kg body weight), AST group (100 mg/kg body weight), and AST intervention group (100 mg/kg body weight AST+5 mg/kg body weight OTA). It was found that AST decreased the endotoxin content, effectively prevented the shortening of mouse cecum villi, and increased the expression levels of tight junction (TJ) proteins, consisting of occludin, claudin-1, and zonula occludens-1 (ZO-1). AST increased the number of goblet cells, the contents of mucin-2 (MUC2), and defensins (Defa5 and β-pD2) significantly, while the expression of mucin-1 (MUC1) decreased significantly. The 16S rRNA sequencing showed that AST affected the richness and diversity of cecum flora, decreased the proportion of lactobacillus, and also decreased the contents of short-chain fatty acids (SCFAs) (acetate and butyrate). In addition, AST significantly decreased the expression of TLR4, MyD88, and p-p65, while increasing the expression of p65. Meanwhile, the expression of inflammatory factors including TNF-α and INF-γ decreased, while the expression of IL-10 increased. In conclusion, AST reduced OTA-induced cecum injury by regulating the cecum barrier function and TLR4/MyD88/NF-κB signaling pathway.

The title compound, [Mo3(C31H46NS2)3S7]I, crystallizes on a threefold rotational axis in P31c (space group No. 159). The [Mo3S7(S2CN(CH2C6H3-3,5- t Bu2)2)3]+ cations are arrayed in sheets in the ab plane with interligand hydrophobic interactions between tert-butyl groups guiding the packing arrangement. These cations form stacks parallel to the c axis with a separating distance of 10.9815 (6) Å (the c axis length) between the Mo3 centroids. On the underside of the cluster, opposite the μ3-S2− ligand, the iodide counteranion forms close contacts of 3.166 (2) Å with the sulfur atoms of the μ2-S2 2− ligands. These contacts are less than the sum of the van der Waals radii of the atoms (1.8 and 2.1 Å for S and I, respectively), thus indicating an appreciable degree of covalency to the [Mo3S7(S2CN(CH2C6H3-3,5- t Bu2)2)3]+...I− interactions.

Uncertainties in the Noah with multiparameterization (Noah-MP) land surface model are assessed through physics ensemble simulations in four sparsely vegetated sites located in the central and western Tibetan Plateau. The simulated hydrological components are evaluated using observations at those sites during the third Tibetan Plateau Experiment from August 1st, 2014 to August 1st, 2015. By using natural selection, the crucial subprocesses impacting the hydrological component simulations are identified. The effects of precipitation uncertainties and soil organic matter on the energy fluxes and water cycles are analyzed through a set of sensitivity experiments based on an optimal scheme set. The uncertainty analyses indicate that the greatest uncertainties are in the subprocesses of runoff (RNF) and groundwater, surface-layer parameterization and frozen soil permeability, along with the subprocesses of snow surface albedo and the lower boundary of soil temperature for the bare ground site but the subprocesses of the canopy resistance and soil moisture limiting factors for evaporation for the three alpine grassland sites. The sensitivity analyses reveal that more precipitation can increase the annual total net radiation (Rn), latent heat flux (LE) and RNF but decrease sensible heat flux (SH). Compared to the insufficient precipitation, the relatively small increase in precipitation results in the LE increase during the growing season at the Amdo and Baingoin sites but an RNF increase at the Nagqu site (sandy soil). However, when more precipitation was added, a greater proportion of the added water was distributed to the RNF at the Nagqu site and to the soil liquid water at the Amdo and Baingoin sites. The organic soil increases the annual total LE but reduces the annual total Rn, SH, and RNF. The effect of the soil organic matter on the LE and RNF at the Nagqu site (sandy soil), is greater than that at the other three sites (sandy loam soil).

Observations of the surface heat fluxes can be used to evaluate and improve land-surface models (LSMs). There are significant uncertainties, however, in measured surface-energy budgets, especially for the heterogeneous Tibetan Plateau (TP) region where the observation conditions are harsh. In this study, summer (July-October 2014) surface flux data were obtained using the eddy covariance method from ten sites over the TP during the Third Tibetan Plateau Atmospheric Scientific Experiments. Data analysis was performed to assess the surface-energy balance ratio (SEBR= H + LE/(Rn-G)) and associated uncertainties across various land-cover types and elevation heights. Measured latent heat fluxes were positive during nighttime and exhibit substantially greater uncertainty than the sensible heat fluxes. The ten-site averaged SEBR was 74.2 ± 5.4%, largely on par with reported SEBR for other regions. SEBR values were similar among homogeneous sites, and the averaged SEBR (93.4%) for those sites was better than that (67.3%) for the heterogeneous sites. The soil heat storage term represents the most significant source of uncertainty (8.2%) than the canopy storage term (0.22%) to closing the surface energy budget. The SEBR showed a strong diurnal cycle and the midday (10:00∼15:00 local time) values were higher than those nearest sunrise and sunset times. The late-night SEBR (00:00∼6:00 local time) at sites located at higher elevations were more reliable than those at lower elevation sites, because of the frequent occurrence of neutral conditions (instead of stable or very stable conditions) at high terrains. The relationships between SEBR and surface-layer turbulent parameters (ξ, u*,θ*) and wind direction were investigated. An uncertainty range for measured surface heat fluxes was derived to provide a meaningful guidance for applying these observations in evaluating LSMs.

Background Core-shell-structured nanoparticles (NPs) have attracted much scientific attention due to their promising potential in biomedical fields in recent years. However, their underlying mechanisms of action and potential adverse effects following administration remain unknown. Methods In the present study, a 1H nuclear magnetic resonance-based metabonomic strategy was applied to investigate the metabolic consequences in rats following the intravenous administration of parent NPs of core-shell-structured nanoparticles, Fe3O4@SiO2-NH2 (Fe@Si) NPs. Results Alterations reflected in plasma and urinary metabonomes indicated that Fe@Si NPs induced metabolic perturbation in choline, ketone-body, and amino-acid metabolism besides the common metabolic disorders in tricarboxylic acid cycle, lipids, and glycogen metabolism often induced by the exogenous agents. Additionally, intestinal flora metabolism and the urea cycle were also influenced by Fe@Si NP exposure. Time-dependent biological effects revealed obvious metabolic regression, dose-dependent biological effects implied different biochemical mechanisms between low- and high-dose Fe@Si NPs, and size-dependent biological effects provided potential windows for size optimization. Conclusion Nuclear magnetic resonance-based metabonomic analysis helps in understanding the biological mechanisms of Fe@Si NPs, provides an identifiable ground for the selection of view windows, and further serves the clinical translation of Fe@Si NP-derived and -modified bioprobes or bioagents.

The crystal structure of tetra­iso­butyl­thiuram di­sulfide reveals a −85.81 (1)° C—S—C—S torsion angle and multiple intra- and inter­molecular S⋯C—H close contacts., Tetra­kis(2-methyl­prop­yl)thio­per­oxy­dicarbonic di­amide, or tetra­iso­butyl­thiuram di­sulfide, C18H36N2S4, crystallizes in a general position in the triclinic space group P-1 but shows pseudo-C 2 symmetry about the di­sulfide bond. The C—S—S—C torsion angle [−85.81 (2)°] and the dihedral angle between the two NCS2 mean planes [85.91 (5)°] are within the range observed for this compound type. Multiple intra- and inter­molecular S⋯H—C close contacts appear to play a role in assisting the specific conformation of the pendant isobutyl groups and the packing arrangement of mol­ecules within the cell. Tetra­iso­butyl­thiuram di­sulfide mol­ecules of one optical configuration form sheets in the plane of the a and b axes. Inversion centers exist between adjoining sheets, which stack along the c axis and alternate in the handedness of their constituent mol­ecules.

Inclusion of the thermal and hydraulic effect of soil organic matter plays an important role in land-surface models (LSMs) for simulating soil temperature and surface energy exchanges. The current officially released Noah with multiparameterization (Noah-MP) LSM, implemented in the community Weather Research and Forecasting (WRF) model, does not include a parameterization for soil organic matter. In this study, the thermal and hydraulic effect of soil organic matter was parameterized into Noah-MP LSM. Based on the profiled soil organic matter data for China and the observations of skin temperature and soil temperature profiles from more than 2000 surface meteorological stations, we investigated the effects of organic soil using the Noah-MP LSM with and without the profiled soil organic matter at the regional scales. Compared with the simulation without the inclusion of organic soil parameterization, the Noah-MP LSM simulation with the profiled soil organic matter improved the skin temperature and soil temperature profiles, especially soil temperature in deep soils under cold and arid regions. The realistic representation of snow depth and the snow insulation dependency on snow depth were confirmed to be a pre-requisite in Noah-MP in the high latitudes. By incorporating the profiled soil organic matter, the Noah-MP LSM enlarged the regional mean sensible heat flux (SH) and lower the regional mean latent heat flux (LH). In the warm and humid regions, a relatively smaller effect of organic soil on soil temperature could lead to a larger effect on SH and LH, especially LH.

The aim was to investigate whether selenium-enriched yeast (SeY) can attenuate intestinal injury in broiler chickens induced by ochratoxin A (OTA). Here, the results showed that SeY addition increased the body weight, feed conversion ratio, villi height, villus/crypt ratio, and the numbers of goblet cells. Furthermore, the levels of oxidative stress by SeY addition (superoxide dismutase activity, total antioxidant capacity, and total glutathione content) were significantly decreased (P

Core-shell structured Fe

Background Core–shell-structured nanoparticles (NPs) have attracted much scientific attention due to their promising potential in biomedical fields in recent years. However, their underlying mechanisms of action and potential adverse effects following administration remain unknown. Methods In the present study, a 1H nuclear magnetic resonance-based metabonomic strategy was applied to investigate the metabolic consequences in rats following the intravenous administration of parent NPs of core–shell-structured nanoparticles, Fe3O4@SiO2-NH2 (Fe@Si) NPs. Results Alterations reflected in plasma and urinary metabonomes indicated that Fe@Si NPs induced metabolic perturbation in choline, ketone-body, and amino-acid metabolism besides the common metabolic disorders in tricarboxylic acid cycle, lipids, and glycogen metabolism often induced by the exogenous agents. Additionally, intestinal flora metabolism and the urea cycle were also influenced by Fe@Si NP exposure. Time-dependent biological effects revealed obvious metabolic regression, dose-dependent biological effects implied different biochemical mechanisms between low- and high-dose Fe@Si NPs, and size-dependent biological effects provided potential windows for size optimization. Conclusion Nuclear magnetic resonance-based metabonomic analysis helps in understanding the biological mechanisms of Fe@Si NPs, provides an identifiable ground for the selection of view windows, and further serves the clinical translation of Fe@Si NP-derived and -modified bioprobes or bioagents.

Core–shell structured Fe3O4@SiO2-NH2 nanoparticles (Fe@Si-NPs) demonstrated outstanding potentials in drug targeting and delivery and medical imaging. However, they have limited clinical applications due to unknown chronic bio-effects and potential bio-related risks. In this study, the subchronic biological effects and metabolic fate of 20 nm Fe@Si-NPs in Sprague–Dawley rats in 12 weeks were investigated by the biochemical assay and NMR-based metabonomic analysis using an intravenous model. Biofluids (plasma and urine) analysis provided the transportation, absorption, and excretion information of Fe@Si-NPs. Urine metabonome displayed a metabolic recovery while self-regulation of plasma metabonome leaded to the parallel metabolic trends between dosed and control groups in 12 weeks. And biological tissues (spleen, liver, kidney, and lung) analysis indicated liver and spleen are the targeted-organs of Fe@Si-NPs. The obvious metabolic variations responding to the biodistribution were induced by Fe@Si-NPs although no visible toxic effects were observed in these tissues. Besides the common energy metabolism response to the xenobiotics, Fe@Si-NPs also disturbed the metabolic pathways in glycerophospholipid and sphingolipid metabolism, metabolisms of purine, pyrimidine, and nicotinate. Our results provide preliminary validation for the potential use of Fe@Si-NPs in clinical medicine and give identifiable ground for the dose selection and bio-nanoagent optimization.

In this paper, a nonlinear saturation controller is improved by using quadratic velocity coupling term with time delay instead of the original quadratic position coupling term in the controller and adding a negative time-delay velocity feedback to the primary system. The improved controller is utilized to control the high-amplitude vibration of a flexible, geometrically nonlinear beam-like structure when the primary resonance and the 1:2 internal resonance occur simultaneously. To explain analytically mechanism of the saturation controlled system, an integral iterative method is presented to obtain the second-order approximations and the amplitude equations. It is shown that the quadratic velocity coupling term can enlarge the effective frequency bandwidth and enhance the performance of the vibration suppression by comparison with the quadratic position coupling term, and the linear velocity feedback can suppress the transient vibrations. The effects of different control parameters on saturation control are investigated. We found that time delays can be used as control parameters to change the effective frequency bandwidth and avoid the controller overload risk. The analyses show that numerical simulations are in good agreement with the analytical solutions.

In this paper, a nonlinear delayed absorber is proposed by a delayed feedback loop and is utilized to absorb or suppress the vibration of a two-degree-of-freedom nonlinear system when the primary resonance and the 1:1 internal resonance occur simultaneously. To explain analytically mechanism of performance of the absorber, an integral equation method is provided to obtain the second order approximation and the amplitude equations. As a result, the feedback gain and time delay which make the amplitude of the main system equal to zero can be derived analytically. Optimal working conditions of the system are extracted from the time delay-response curves, the force-response curves and the frequency-response curves. In the illustrative example, the appropriate choice of feedback gains and time delays can reduce the amplitude of the main system by more than $$98\,\%$$ in comparison with the amplitude with no time delay. All analytical predictions are in excellent agreement with the numerical simulations.

The aim of this research was to evaluate the potential protective mechanism of astaxanthin (ASTA) against oxidative damage and inflammation caused by ochratoxin (OTA) in mouse lung. We divided mice into a control group (CG), an OTA group (PG), an astaxanthin group (AG), and an OTA+ASTA group (JG). Oxidative indices (malondialdehyde (MDA), total superoxide dismutase (T-SOD), and reduced glutathione (GSH)) and inflammatory markers (interleukin 1&beta, (IL-1&beta, ), interleukin 6 (IL-6), and tumor necrosis factor &alpha, (TNF-&alpha, )) were assayed in the lung, and the lung-weight-to-body-weight ratio was calculated. Apoptosis was detected in pathological sections by the TdT-mediated dUTP nick-end labeling (TUNEL) assay. Oxidative damage and inflammation were detected in the lung of mice after exposure to OTA. Besides, Nrf2- and NF-&kappa, B-pathway-associated proteins were detected by Western blot. In contrast with OTA, ASTA significantly raised the expression of Nrf2, HO-1, and MnSOD, while the expression of other proteins (Keap1, TLR4, and NF-&kappa, B) was significantly decreased. These results indicate that ASTA exerted protective effects against OTA-induced oxidative damage and inflammation in the lung by regulating the Nrf2 and NF-&kappa, B pathways.

In this paper, we compare two approaches for determining the amplitude equations; namely, the integral equation method and the method of multiple scales. To describe and compare the methods, we consider three examples: the parametric resonance of a Van der Pol oscillator under state feedback control with a time delay, the primary resonance of a harmonically forced Duffing oscillator under state feedback control with a time delay, and the primary resonance together with 1:1 internal resonance of a two degree-of-freedom model. Using the integral equation method and the method of multiple scales, the amplitude equations are obtained. The stability of the periodic solution is examined by using the Floquet theorem together with the Routh–Hurwitz criterion (without time delay) and the Nyquist criterion (with time delay). By comparison with the solution obtained by the numerical integration, we find that the accuracy of the integral equation method is much better.

Using Green's function for third-order differential equation and some fixed-point theorems, i.e., Leray-Schauder alternative principle and Schauder's fixed point theorem, we establish three new existence results of periodic solutions for nonlinear third-order singular differential equation, which extend and improve significantly existing results in the literature.

By applying Green's function of third-order differential equation and a fixed point theorem in cones, we obtain some sufficient conditions for existence, nonexistence, multiplicity, and Lyapunov stability of positive periodic solutions for a third-order neutral differential equation.

We report the existence of polarization memory effect (PME) in optical coherence tomography and investigate its potential applications in dental imaging. We performed the study in three steps. First, microsphere scattering phantoms of different sizes were imaged in order to validate experimental results with PME theory. Both linearly and circularly polarized light were used to probe the samples. Second, healthy tooth samples were scanned and polarization memory effect was identified in dentin. In this step, specific verification and signal processing were performed to rule out possible image interpretation by birefringence effect. Third, we evaluated dentin demineralization with PME. Results show polarization memory can be useful to characterize this dynamic mineralization process for early caries detection and rehabilitation. C 2011 Society of Photo-Optical Instrumentation Engineers

The sewage from high-temperature gas field containing H 2 S has following features: high H 2 S content, high temperatures and high salinity. Coupon test, microscopic observation of corrosion images and other methods have been used in the research of the corrosion behavior of high-temperature H 2 S-contained sewage to N80 steel. The sewage corrosion behavior to N80 steel starts from the adsorption of sulfur particles, the corrosion products are a variety of iron sulfide and other compounds of trivalent iron, and the iron sulfide formation of passive film shows the trend of densification at high temperature. As the pH value of the sewage decreases, the corrosive enhances, the smoothness and oxide on the surface of N80 steel can affect the corrosion. The increasing oxygen content leads to the higher corrosion effect. In the sewage, the high concentration of Cl− ions accelerates the N80 steel corrosion caused by S2− and HS−. And the HS− concentration in the sewage is the main factor that influences on the corrosion performance to N80 steel.

PURPOSE. To investigate the characteristics of a spectral-domain optical coherence tomography (SD-OCT) image phenomenon known as the mirror artifact, calculate its prevalence, analyze potential risk factors, measure severity, and correlate it to spherical equivalent and central visual acuity (VA). METHODS. OCT macular cube 512 x 128 scans taken between January 2008 and February 2009 at the New England Eye Center were analyzed for the presence of mirror artifacts. Artifact severity was determined by the degree of segmentation breakdown that it caused on the macular map. A retrospective review was conducted of the medical records of patients with artifacts and of a random control group without artifacts. RESULTS. Of 1592 patients, 9.3% (148 patients, 200 eyes) had scans that contained mirror artifacts. A significantly more myopic spherical equivalent (P < 0.001), worse VA (P < 0.001), longer axial lengths (P = 0.004), and higher proportions of moderate to high myopia (P < 0.001) were found in patients with mirror artifacts than in patients without artifacts. Worse VA was associated with increased artifact severity (P = 0.04). CONCLUSIONS. In all scans analyzed, a high prevalence of mirror artifacts was found. This image artifact was often associated with patients with moderate to high myopia. Improvements in instrumentation may be necessary to resolve this problem in moderately and highly myopic eyes. Operators should be advised to properly position the retina when scanning eyes. In cases in which peripheral abnormalities in topographic measurements of retinal thickness are found, corresponding OCT scans should be examined for the presence of mirror artifacts.

Advanced Imaging Group, Thorlabs, Inc., Newton, NJ ABSTRACT We performed OCT imaging of the rat retin a at 70,000 axial scans per second with ~3 m axial resolution. Three-dimensional OCT (3D-OCT) data sets of the rat retina were acquired. The high speed and high density data sets enable improved en face visualization by reducing eye moti on artifacts and improve Doppler OCT measurements. Minimal motion artifacts were visible and the OCT fundus images offer more precise registration of individual OCT images to retinal fundus features. Projection OCT fundus images show features such as the nerve fiber layer, retinal capillary networks and choroidal vasculature. Doppler OCT images and quantitative measurements show pulsatility in retinal blood vessels. Doppler OCT provides non-invasive in vivo quantitative measurements of retinal blood flow properties and may benefit studies of diseases such as glaucoma and diabetic retinopathy. Ultrahigh speed imaging using ultrahigh resolution spectral / Fourier domain OCT promises to enable novel protocols for measuring small animal retinal structure and retinal blood flow. This non-invasive imaging technology is a promising tool for monitoring disease progression in rat and mouse models to assess ocul ar disease pathogenesis and response to treatment. Keywords: Ultrahigh resolution OCT, ultrahigh speed OCT, spectral/Fourier domain OCT, Doppler OCT, small animal imaging * liujj@mit.edu; phone 1 617 253-8140; fa x 1 617 253-9611; www.rle.mit.edu

Ultrahigh speed Spectral/Fourier domain ophthalmic OCT imaging at 70,000–312,500 axial scans per second is demonstrated using a high speed CMOS camera at 800 nm. Comparative imaging results of the fovea illustrate the performance tradeoffs between different imaging speeds and spectrometer configurations. Dense 3D volumetric acquisitions show minimal motion artifacts when acquired at 250,000 axial scans per second. The porous structure of the lamina cribrosa is shown in en face images extracted from a dense volumetric acquisition of the optical nerve head acquired at 106, 382 axial scans per second. Rapid repeated volume imaging (4D-OCT) shows blood flow in retinal capillaries. Boundaries of the capillary network are enhanced by motion contrast. 3D volumetric data acquired at 49,000 axial scans per second using an InGaAs camera at 1050 nm is compared to volumetric data acquired at 101, 010 axial scans per second using a CMOS camera at 800nm. Averaging of adjacent cross sectional scans in the volume is shown to increase contrast in the images and reduce speckle. The enhanced penetration of the 1050 nm compared to the 800 nm OCT imaging system is shown. Dense 2D/3D data sets and 4D-OCT repeated volume imaging promise alternative methods for diagnosis and monitoring of disease.

Ultrahigh speed spectral / Fourier domain optical coherence tomography (OCT) using a CMOS line scan camera with image acquisition rates of 70,000 - 312,500 axial scans per second is investigated. Several design configurations are presented to illustrate design trade-offs between acquisition speed, sensitivity, resolution and sensitivity roll-off performance. We demonstrate: extended imaging range and improved sensitivity roll-off at 70,000 axial scans per second with 4096 camera pixels, high speed and ultrahigh resolution imaging at 106,382 axial scans per second, and ultrahigh speed imaging at 250,000-312,500 axial scans per second. Each configuration is characterized through optical testing and the trade-offs demonstrated with in vivo imaging of the fovea and optic disk in the human retina. We show dense homogeneous 3D-OCT volumetric data sets that were acquired by raster scanning at 250,000 axial scans per second, which is an order of magnitude faster than most current generation spectral / Fourier OCT instruments. OCT fundus images constructed from the 3D-OCT data have no noticeable discontinuity of retinal features and show that there are minimal motion artifacts. Using an improved sensitivity roll-off configuration at 70,000 axial scans per second, long cross sectional scans are acquired at high resolution for imaging large areas of the retina, including the fovea and optic disk. Using an ultrahigh speed configuration at 250,000 axial scans per second, the fine porous structures of the lamina cribrosa can be seen from slices extracted from a dense 3D data set. Rapid repeated imaging of a small volume (4D-OCT) enables time resolved visualization of the capillary network surrounding the INL and may show individual red blood cells. This capability could create the possibility for alternative techniques for quantifying capillary blood flow, which cannot be measured with Doppler OCT methods because of the capillary’s perpendicular orientation to the optical beam. The results of this study suggest that high speed CMOS cameras can achieve a significant improvement in performance for ophthalmic imaging. This promises to have a powerful impact in clinical applications by improving early diagnosis, reproducibility of quantitative measurements and enabling more sensitive assessment of disease progression or response to therapy.

Angiogenesis in advanced breast cancers is highly distorted and heterogeneous. Non-invasive imaging that can monitor angiogenesis may be invaluable for assessing tumor response to treatment. By combining ultrasound and near infrared optical imaging, a reliable new technique has emerged for predicting tumor angiogenesis within the breast.

We designed a polarization-sensitive optical coherence tomography (PS-OCT) system to study the tissue polarization properties. The system has a dual-configuration scheme with the capability of easily switching the state of probing beam in the sample arm between linear polarization (LP) and circular polarization (CP). This setup will give four sets of 2-D tomographic data for each sample measurement, thus reveal more polarization information embedded in the biological tissue than a standard two-channel CP-configured PS-OCT system. The imaging results of LPCP-OCT for dentin and enamel of tooth samples are compared and discussed.