Impact Analysis of Solar Irradiance Change on Precision Orbit Determination of Navigation Satellites

Solar radiation pressure is the main driving force and error source for precision orbit determination of navigation satellites.It is proportional to the solar irradiance,which is the"sun constant".In regular calculation,the"solar constant"is regard as a constant.However,due to the existence of sunspots,flares,etc.,the solar constant is not fixed,the change in the year is about 1%.To investigate the variation of solar irradiance,we use interpolation and average segment modeling of total solar irradiance data of SORCE,establishing variance solar radiation pressure(VARSRP)model and average solar radiation pressure(AVESRP)model based on the built solar pressure model(SRPM)(constant model).According to observation data of global positioning system(GPS)and Beidou system(BDS)in 2015 and comparing the solar pressure acceleration of VARSRP,AVESRP and SRPM,the magnitude of change can reach 10-10 m/s^2.In addition,according to the satellite precise orbit determination,for GPS satellites,the results of VARSRP and AVESRP are slightly smaller than those of the SRPM model,and the improvement is between 0.1 to 0.5 mm.For geosynchronous orbit(GEO)satellites of BDS,The AVESRP and VARSRP have an improvement of 3.5 mm and 4.0 mm,respectively,based on overlapping arc,and SLR check results show the AVESRP model and the VARSRP model is improved by 2.3 mm and 3.5 mm,respectively.Moreover,the change of inclined geosynchronous orbit(IGSO)satellites and medium earth orbit(MEO)satellites is relatively small,and the improvement is smaller than 0.5 mm.

LUNG DOSE DETERMINATION IN TOTAL BODY IRRADIATION PRIOR TO BONE MARROW TRANSPLANTATION

Total body irradiation (TBI) combined with chemotherapy prior to bone marrow transplantation (BMT) is used successfully for treatment leukemias. It need a high and homogeneous radiation dose to all target cells, dispersed In the whole body. The lung is the most sensitive vital organ at risk in TBI. The lung dose must be within it' s tolerable level. So, the determination of the lung dose is most Important for TBI. The determination of the lung dose is dependent on at least 8 parameters. In order to determine the effect of 8 parameters on the lung dose, using a system of phantom of Essen University hospital in F. R. Germany, a lot of measurements and a systematical investigation was made by varying 8 parameters, under the Essen translation TBI conditions. A analysis and discussion of results was made.

Hot-Carrier Effects on Total Dose Irradiated 65 nm n-Type Metal-Oxide-Semiconductor Field-Effect Transistors

The influence of total dose irradiation on hot-carrier reliability of 65 nm n-type metal-oxide-semiconductor field- effect transistors （nMOSFETs） is investigated. Experimental results show that hot-carrier degradations on ir- radiated narrow channel nMOSFETs are greater than those without irradiation. The reason is attributed to radiation-induced charge trapping in shallow trench isolation （STI）. The electric field in the pinch-off region of the nMOSFET is enhanced by radiation-induced charge trapping in STI, resulting in a more severe hot-carrier effect.

Pattern imprinting in deep sub-micron static random access memories induced by total dose irradiation

Pattem imprinting in deep sub-micron static random access memories （SRAMs） during total dose irradiation is inves- tigated in detail. As the dose accumulates, the data pattern of memory cells loading during irradiation is gradually imprinted on their background data pattern. We build a relationship between the memory cell＇s static noise margin （SNM） and the background data, and study the influence of irradiation on the probability density function of ASNM, which is the difference between two data sides＇ SNMs, to discuss the reason for pattern imprinting. Finally, we demonstrate that, for micron and deep sub-micron devices, the mechanism of pattern imprinting is the bias-dependent threshold shift of the transistor, but for a deep sub-micron device the shift results from charge trapping in the shallow trench isolation （STI） oxide rather than from the gate oxide of the micron-device.

Analysis of functional failure mode of commercial deep sub-micron SRAM induced by total dose irradiation

Functional failure mode of commercial deep sub-micron static random access memory（SRAM） induced by total dose irradiation is experimentally analyzed and verified by circuit simulation. We extensively characterize the functional failure mode of the device by testing its electrical parameters and function with test patterns covering different functional failure modes. Experimental results reveal that the functional failure mode of the device is a temporary function interruption caused by peripheral circuits being sensitive to the standby current rising. By including radiation-induced threshold shift and off-state leakage current in memory cell transistors, we simulate the influence of radiation on the functionality of the memory cell. Simulation results reveal that the memory cell is tolerant to irradiation due to its high stability, which agrees with our experimental result.

Influence of Total Ionizing Dose Irradiation on Low-Frequency Noise Responses in Partially Depleted SOI nMOSFETs

Total ionizing dose effect induced low frequency degradations in 130nm partially depleted silicon-on-insulator （SOI） technology are studied by ^60Co γ -ray irradiation. The experimental results show that the flicker noise at the front gate is not affected by the radiation since the radiation induced trapped charge in the thin gate oxide can be ignored. However, both the Lorenz spectrum noise, which is related to the linear kink effect （LKE） at the front gate, and the flicker noise at the back gate are sensitive to radiation. The radiation induced trapped charge in shallow trench isolation and the buried oxide can deplete the nearby body region and can activate the traps which reside in the depletion region. These traps act as a GR center and accelerate the consumption of the accumulated holes in the floating body. It results in the attenuation of the LKE and the increase of the Lorenz spectrum noise. Simultaneously, the radiation induced trapped charge in the buried oxide can directly lead to an enhanced flicker noise at the back gate. The trapped charge density in the buried oxide is extracted to increase from 2.21×10^18 eV^-1 cm^-3 to 3.59×10^18？eV^-1 cm^-3 after irradiation.

Low Dose Total Body Irradiation (600 cGy) as a Conditioning Regimen in Allogenic Hematopoietic Stem Cell Transplant in Children with Acute Lymphoblastic Leukemia

Total body irradiation (TBI) is conditioning regimen in children with acute lymphoblastic leukemia (ALL) with a very high risk of relapse or in those who have not achieved remission and have relapsed and subsequently received allogenic hematopoietic stem cell transplantation (HSCT). A retrospective evaluation of 33 ALL patients in full remission with an indication of HSCT was performed to evaluate overall survival (OS) and event-free survival (EFS). The inclusion criteria included a myeloablative conditioning regimen of TBI at a dose of 600 cGy. The observed OS at 5 years was 50%, and the EFS of 32% we observed difference in the EFS stem cell origin;the peripheral blood (PB) 60%, and the umbilical cord blood (UC) accounted for 40%. Overall, 45% had a documented chimerism. The OS at 5 years from patients with chimeras was 75%, while those without chimeras had an OS at 5 years of 25%. The mortality in the first 100 days was 24%. A total of 24.2% of children presented with acute graft versus-host disease (GVHD), while 33% had chronic GVHD. Currently, there is no general agreement among all international centers regarding the optimum TBI dose. Our study reports an acceptable range of adverse events with a relatively low dose of 600 cGy.

The protective effects of Xuebijing injection on intestinal injuries of mice exposed to irradiation

Background:Gastrointestinal(GI)injury is one of the most common side effects of radiotherapy.However,there is no ideal therapy method except for symptomatic treatment in the clinic.Xuebijing(XBJ)is a traditional Chinese medicine,used to treat sepsis by injection.In this study,the protective effects of XBJ on radiation-i nduced intestinal injury(RⅢ)and its mechanism were explored.Methods:The effect of XBJ on survival of irradiated C57BL/6 mice was monitored.Histological changes including the number of crypts and the length of villi were evaluated by H&E.The expression of Lgr5^(+)intestinal stem cells(ISCs),Ki67^(+)cells,villin and lysozymes were examined by immunohistochemistry.The expression of cytokines in the intestinal crypt was detected by RT-PCR.DNA damage and apoptosis rates in the small intestine were also evaluated by immunofluorescence.Results:In the present study,XBJ improved the survival rate of the mice after 8.0and 9.0 Gy total body irradiation(TBI).XBJ attenuated structural damage of the small intestine,maintained regenerative ability and promoted proliferation and differentiation of crypt cells,decreased apoptosis rate and reduced DNA damage in the intestine.Elevation of IL-6 and TNF-α was limited,but IL-1,TNF-β and IL-10 levels were increased in XBJ-treated group after irradiation.The expression of Bax and p53 were decreased after XBJ treatment.Conclusions:Taken together,XBJ provides a protective effect on RⅢby inhibiting inflammation and blocking p53-related apoptosis pathway.

TBI Technique Improvements for Anesthetized Pediatric Patients Based on Near-Miss Incident Reporting

Purpose: To share our clinical experience of an optimized and comprehensive pediatric TBI technique. Methods and Materials: Through the use of incident learning, safety-critical areas were identified in our procedure for total body irradiation (TBI) for pediatric patients under anesthesia for bone-marrow transplant. The previous procedure lacked flexibility to accommodate various requests from the anesthesia team due to the wide range of patient sizes. To address this issue and to improve the process overall, we updated our procedure for TBI simulation, dosimetry planning, patient setup during treatment, and in vivo dosimetry. A simulation form was redesigned with additional detailed instructions and documentation requirements. The dose calculation procedure was reformulated to remove dependence on setup variations. Tissue compensation determination and therefore dose uniformity were improved by introducing rigorous calculation methods. Calculations were performed on 28 previously-treated patients to compare the dose uniformity using the new versus previous methods. Results: The new procedures improve interdepartmental communication, simplify the workflow, decrease the risk of treating patients in a setup that differs from that used during the simulation, and reduce dose heterogeneity. The new compensator design significantly improved patient dose uniformity: 0.8% ± 0.4% (new method) vs. 4.2% ± 2.3% (previous method) (p Conclusion: A near-miss incident reporting system was used to improve the safety and quality of pediatric TBI procedures under anesthesia.

Computational and Experimental Approaches for Evaluating Dose under a Block in TBI Geometry

Total Body Irradiation (TBI) patients are often treated at extended distances of several meters, with blocking made from high-Z materials placed close to the patients’ skin. Evaluating the dose under a block (e.g., for implanted medical device shielding purposes) in such a geometry is challenging. We compare the performance of two commonly used dose calculation algorithms, Anisotropic Analytical Algorithm (AAA) and Acuros XB, with Optically Stimulated Lumine- scence (OSLD) and ion chamber measurements in phantoms. The calculations and phantom measurements are also compared with in-vivo OSLD measure- ments. We find that OSLD and ion chamber measurements in phantom are good predictors of in-vivo measurements, while both AAA and Acuros XB sys- tematically overestimate the block transmission. We found Acuros XB to be accurate enough for a rough upper estimate (dose under block overestimated by 7% - 22%), while for AAA the overestimate was more severe (90% - 110%);the reason is that AAA does not account for the increase in pair production cro- ss-section in high-Z materials.

Perceiving the Trend of Terrestrial Climate Change during the Past 40 year(1978-2018)

In past few decades,climate has manifested numerous shifts in its trend.Various natural and anthropogenic factors have influenced the dynamics and the trends of climate change at longer time scale.To understand the long term climate fluctuations,we have analyzed forty years(1978-2018)data of ten climatic parameters that are responsible to influence the climate dynamics.The parameters involved in the present study are total solar irradiance(TSI),ultra violet(UV)index,cloud cover,carbon dioxide(CO2)abundances,multivariate(ENSO)index,volcanic explosivity index(VEI),global surface temperature(GST)anomaly,global sea ice extent,global mean sea level and global precipitation anomaly.Using the above mentioned climate entities;we have constructed a proxy index to study the quantitative measure of the climate change.In this process these indicators were aggregated to a single proxy index as global climate index(GCI)that has measured the strength of present climate change in semblance with the past natural variability.To construct GCI,the principal component analysis(PCA)has been used on yearly based data for the period 1978-2018.Actually PCA is a statistical tool with which we can reduce the dimensionality of the data and it retains most of the variation in the new data set.Further,we have confined our study to natural climate drivers and anthropogenic climate drivers.Our result has indicated that the strongest climate change has been occurred globally by the end of the year 2018 in comparison to late 1970’s natural variability.

Allogeneic compact bone-derived mesenchymal stem cell transplantation increases survival of mice exposed to lethal total body irradiation： a potential immunological mechanism

Background Radiation-induced injury after accidental or therapeutic total body exposure to ionizing radiation has serious pathophysiological consequences,and currently no effective therapy exists.This study was designed to investigate whether transplantation of allogeneic murine compact bone derived-mesenchymal stem cells （CB-MSCs） could improve the survival of mice exposed to lethal dosage total body irradiation （TBI）,and to explore the potential immunoprotective role of MSCs.Methods BALB/c mice were treated with 8 Gy TBI,and then some were administered CB-MSCs isolated from C57BL/6 mice.Survival rates and body weight were analyzed for 14 days post-irradiation.At three days post-irradiation,we evaluated IFN-Y and IL-4 concentrations; CD4＋CD25＋Foxp3＋ regulatory T cell （Treg） percentage; CXCR3,CCR5,and CCR7 expressions on CD3＋T cells; and splenocyte T-bet and GATA-3 mRNA levels.CB-MSC effects on bone marrow hemopoiesis were assessed via colony-forming unit granulocyte/macrophage （CFU-GM） assay.Results After lethal TBI,compared to non-transplanted mice,CB-MSC-transplanted mice exhibited significantly increased survival,body weight,and CFU-GM counts of bone marrow cells （P＜0.05）,as well as higher Treg percentages,reduced IFN-Y,CXCR3 and CCR5 down-regulation,and CCR7 up-regulation.CB-MSC transplantation suppressed Th1 immunity.Irradiated splenocytes directly suppressed CFU-GM formation from bone marrow cells,and CB-MSC co-culture reversed this inhibition.Conclusion Allogeneic CB-MSC transplantation attenuated radiation-induced hematopoietic toxicity,and provided immunoprotection by alleviating lymphocyte-mediated CFU-GM inhibition,expanding Tregs,regulating T cell chemokine receptor expressions,and skewing the Th1/Th2 balance toward anti-inflammatory Th2 polarization.

Total dose irradiation and hot-carrier effects of sub-micro NMOSFETs

Total dose irradiation and the hot-carrier effects of sub-micro NMOSFETs are studied. The results show that the manifestations of damage caused by these two effects are quite different, though the principles of damage formation are somewhat similar. For the total dose irradiation effect, the most notable damage lies in the great increase of the off-state leakage current. As to the hot-carrier effect, most changes come from the decrease of the output characteristics curves as well as the decrease of trans-conductance. It is considered that the oxide-trapped and interface-trapped charges related to STI increase the current during irradiation, while the negative charges generated in the gate oxide, as well as the interface-trapped charges at the gate interface, cause the degradation of the hot-carrier effect. Different aspects should be considered when the device is generally hardened against these two effects.

Enhancement of antitumor immunity by low-dose total body irradiation is associated with selectively decreasing the proportion and number of T regulatory cells

Low-dose total body irradiation （LTBI） is used in the treatment of some cancers mainly for immune enhancement rather than cell killing. However, the mechanism underlying LTBI remains unknown. In this study, by analyzing the immune patterns of lymphocytes, we found that the percentage and absolute number of CD4^＋CD25^＋Foxp3^＋ regulatory T cells are markedly decreased in naive mice following treatment with LTBI. On the contrary, the CD4^＋CD44^＋/CD8^＋CD44^＋ effector-memory T cells are greatly increased. Importantly, naive mice treated with dendritic cell-gp100 tumor vaccines under LTBI induced an enhancement of antigen-specific proliferation and cytotoxicity as well as interferon-γ, （IFN-γ） secretion against FIO melanoma tumor challenge, compared to treatment with either the tumor vaccine or LTBI alone. Consequently, the treatment resulted in a reduced tumor burden and prolonged mouse survival. Our data demonstrate that LTBI＇s enhancement of antitumor immunity was mainly associated with selectively decreasing the proportion and number of T regulatory cells, implying the potential application of the combination of LTBI and a tumor vaccine in antitumor therapy.

A novel terminal structure for total dose irradiation hardened of a P-VDMOS

Using positive surface charge instead of traditional γ-ray total dose irradiation, the electric field distribution of a P-channel VDMOS terminal has been analyzed. A novel terminal structure for improving the total dose irradiation hardened of P-channel VDMOS has been proposed, and the structure is simulated and demonstrated with a -150 V P-channel VDMOS. The results show that the peak current density is reduced from 5.51 × 10^3 A/cm^2 to 2.01 × 10^3 A/cm^2, and the changed value of the breakdown voltage is 2.5 V at 500 krad（Si）. Especially, using 60Co and X-ray to validate the results, which strictly match with the simulated values, there is not any added mask or process to fabricate the novel structure, of which the process is compatible with common P-channel VDMOS processes. The novel terminal structure can be widely used in total irradiation hardened P-channel VDMOS design and fabrication, which holds a great potential application in the space irradiation environment.

Capture of phosphates in surface water by TiO_2 nanoparticles under UV irradiation

The capture of orthophosphates and total phosphorus from the Pudong Canal river in the Pudong District of Shanghai by TiO2 nanoparticles is studied using a rotating photoreactor and the nano-TiO2 photocatalyst Degussa P25. The effects of UV irradiation intensity in a range of 20-74 mW/cm^2, the loading of the TiO2 nanoparticles in a range of 0.05-0.1 g/L, irradiation time up to 4 h, and pH values in a range of 2-10.5 on the capture efficiency are investigated. The results show that the capture of orthophosphates and total P are significantly enhanced by UV irradiation; at a loading of 0.1 g/L and an irradiation intensity above 36 mW/cm^2, orthophosphates and total phosphorus are rapidly captured by TiO2 nanoparticles, causing an observed reduction from 0.4 mg/L down to 0.02 mg/L. pH values in a range of 2-10.5 have little effect on the capture efficiency of orthophosphates and total phosphorus.