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Purpose The purpose of this study is to present the implementation of Six Sigma in a solenoid valve manufacturing company in China. The project aims to reduce the solenoid valve defects, decrease the cost of poor quality, increase customer satisfaction and improve the long-term profitability of Company B. Design/methodology/approach This paper follows the Six Sigma methodology: DMAIC (define, measure, analyse, improve and control) principle of case study research. Hysteresis, the key characteristic of a solenoid valve, is the main chance for quality improvement. This paper emphasizes the solution to the hysteresis problem. During DMAIC phases, the critical factors that affect hysteresis performance are identified for continuous quality improvement of solenoid valve manufacturing. Findings The implementation of Six Sigma leads to a great quality improvement for the company studied in this paper. Control plans are made for good hysteresis performance. As a result, the first pass yield of solenoid valves has increased from 60% to 99.64%. The key hysteresis of the solenoid valve has shown a better performance. Originality/value This study presents a solenoid valve industrial quality improvement case that demonstrates how Six Sigma and DMAIC methodology can be applied to reduce defects and achieve quality improvement in Company B. This study can be referred to for managers and engineers to undertake quality improvement programs.

An overview on the recent progress in bimetallic MOFs regarding their design strategies, syntheses and multifarious applications.

Once-through molten salt reactors have the advantages of easy availability of fuel, nuclear nonproliferation, and low technical difficulty. It is expected to be the earliest commercial molten salt reactor fuel cycle mode. The current research on the neutronic performance of the once-through fuel cycle mainly focuses on the thermal spectrum range, and broader spectrum research needs to be carried out further. In particular, the fuel utilization characteristics of molten salt fast reactors in once-through fuel cycle are not yet clear. In addition, small modular design is one of the trends of molten salt reactor development, and small modular design under thermal and fast spectrum has different advantages and needs further comparative analysis. In this paper, the single lattice, bare reactor, and core with reflector models are used to compare the neutronic performance in once-through fuel cycle from thermal to fast spectrum, which includes burnup, variation of fuel salt composition and volume with burnup, temperature reactivity coefficient, neutron irradiation lifetime, and small modular size. The results show that the burnup increases first, then decreases, and then increases again with the increase of the average lethargy causing fission (EALF). For small-scale molten salt reactors, the difference in fuel utilization under thermal and fast spectra is small. However, for large-scale reactors, the burnup under fast spectrum is significantly higher than that under thermal spectrum. When the EALF is large enough, and the neutron loss ratio is small enough, the breed-and-burn (BNB) fuel cycle mode can be realized, and then, the fuel utilization will be significantly improved. In the fast spectrum reactors, the HN and volume of molten salt change violently because of the longer burnup period. Based on the infinite single lattice model, the temperature reactivity coefficient increases first, then decreases, and increases again with EALF. It is negative over the entire energy spectrum. In addition, the small modular designs are discussed by the bare reactor model, and the neutron irradiation lifetime of the materials is analyzed by the core model with a reflector.

X-linked juvenile retinoschisis (XLRS), caused by the mutation of RS1 gene, is one of the most common causes of macular degeneration for male adolescents. The mutations and clinical manifestations of the disease are diverse. Neither the relationship between the genotypes and phenotypes, nor the radical treatment like gene therapy has been found by now. Retrospective studies have shown that carbonic anhydrase inhibitors can help reduce cysts. However, the specifically pharmacological mechanism remains unknown. Here, we culture induced pluripotent stem cells by drawing peripheral blood from a patient with XLRS, which are supposed to facilitate related researches.

Critical Experiment Device (cold) was established for research on the physics characteristics of Molten Salt Reactor (MSR) in 1970s, at Shanghai Institute of Applied Physics, China. Neutron flux distribution was measured for different core structures and the conversion ratio of the core containing thorium fuel was determined on the basis of the preliminary criticality experiments. The purpose of this work is to compare the calculated flux distribution and thorium-uranium conversion ratio with the measured results in this device. Calculations were accomplished by using MCNP5 code with nuclear data from ENDF/B-VII.0, ENDF/B-VII.1, JEFF 3.2, JENDL 4.0, CENDL 3.1 and ROSFOND 2010 libraries. The results show that the calculated results are in good agreements with the experimental data. Findings in this work have a great significance to the design and benchmark verification of a cold MSR. However, more hot experiments are needed to study the nuclear properties of the liquid fuel MSR.

X-linked juvenile retinoschisis (XLRS) is an inherited disease characterized by splitting within inner retinal layers and impaired vision, which begins in childhood and occurs mostly in males. Peripheral blood mononuclear cells (PBMCs) were isolated from a seven-year-old boy carrying a hemizygous mutation in RS1 gene, and were reprogrammed into human induced pluripotent stem cells (iPSCs) using non-integrative episomal vectors. The cell line, ZOCi003-A, had normal karyotype, expressed pluripotency markers, and could differentiate into three germ layers in vivo. This IPSC line may be used for studying the molecular basis of XLRS and selecting potential therapeutic targets and drugs.

The neutronic properties of molten salt reactors (MSRs) differ from those of traditional solid fuel reactors owing to their nuclear fuel particularity. Based on the Monte-Carlo N particle transport code, the effects of the size and shape of the fuel salt channel on the neutron physics of an MSR cell are investigated systematically in this study. The results show that the infinite multiplication factor (k∞) first increases and then decreases with the change in the graphite cell size under certain fuel volume fraction (FVF) conditions. For the same FVF and average chord length, when the average chord length is relatively small, the k∞ values for different fuel salt channel shapes agree well. When the average chord length is relatively large, the k∞ values for different fuel salt channel shapes differ significantly. In addition, some examples of practical applications of this study are presented, including cell selection for the core and thermal expansion displacement analysis of the cell.

To investigate the predictors of long-term intraocular pressure (IOP) in chronic primary angle-closure glaucoma (CPACG) treated with primary trabeculectomy. This study systematically reviewed cases of CPACG treated with primary trabeculectomy. The scleral flaps in all cases were sutured with two stitches in situ and two releasable sutures to ensure watertight under normal IOP conditions during surgery. Mitomycin C was used in all eyes. All patients were followed for 2 years. Digital massage of the bulbus and removal of the releasable suture were performed according to the IOP and shape of the filtering bleb. Demographic data and clinical outcomes were recorded. Factors predicting long-term IOP were identified. A total of 72 patients (88 eyes) with a mean age of 58.51 ± 10.60 years were included in this study. The complete success rate was 89.77% after 2 years. The IOP began to stabilize after 7 days and reached its lowest point at the 1-month follow-up. The preoperative and early postoperative high or low IOP does not affect long-term effects (P > 0.05). There was a positive correlation between postoperative IOP at the 1-month and 2-year follow-ups (r = 0.64, P

Background: Influenza A(H1N1)pdm09 viruses have undergone rapid evolution, and in recent years the complementary and antagonistic effects of HA and NA have gathered more attentions; however, the effects of co-occurring mutations in HA and NA on the patients’ clinical characteristics are still poorly understood. In this study, we analyzed molecular epidemiology and evolution of A(H1N1) pdm09, explored co-occurring mutations of HA and NA, and investigated effect of co-occurring mutations on patients’ clinical features.Methods: A(H1N1)pdm09 was confirmed by reverse transcription-polymerase chain reaction. HA and NA genes were sequenced and phylogenetically analyzed. Clinical characteristics of the co-occurring mutations were analyzed statistically.Results: By analyzing the HA and NA gene sequences of 33 A(H1N1)pdm09 viruses during the 2015-2017 influenza season, we found that all the viruses shared high similarities to each other and the HA genes of these viruses exclusively belonged to subclade 6B.1A. Several unreported substitutions in HA and NA proteins were observed, furthermore, co-occurring mutations of HA-V169T, A278S, E508G, D518E and NA-V67I were detected in 30.3% (10/33) A(H1N1)pdm09 virus strains when comparing with vaccine strains A/California/07/2009 and A/Michigan/45/2015 (H1N1). Sore throat was significantly associated with co-occurring mutations in HA and NA of A(H1N1)pdm09 (χ2, P < 0.05).Conclusions: Co-occurring mutations in HA and NA were detected in A(H1N1)pdm09 isolated during 2015-2017 in Beijing. Symptomatically, sore throat was associated with co-occurring mutations in HA and NA of A(H1N1)pdm09. Therefore, studying the effect and mechanism of co-occurring mutations in HA and NA on patients’ clinical features is of note needed.

Zero-power experiments are very important parts in design verification for all reactor types. In the 1970s, in China, at the Shanghai Institute of Applied Physics (then, Shanghai Institute of Nucle...

Populus euphratica, the well-known tree halophyte, tolerates the stress of high levels of salt. We previously showed that the transmembrane domain 11 (TM11) of PeNHX3, a Na+,K+/H+ antiporter from P. euphratica, was crucial for Na+ and Li+ transport in a yeast growth assay. Here, we examined the role of TM11 in catalyzing Na+ and Li+ transport in transgenic Arabidopsis. We found that PeNHX3 localized to the tonoplasts in Arabidopsis. Overexpression of PeNHX3 in Arabidopsis improved seedling growth and enhanced salt tolerance and Li+ detoxification. However, overexpression of PeNHX3 did not improve Arabidopsis growth at KCl concentrations higher than 0.1mM, suggesting a low K+ transport activity for PeNHX3 in plants. We performed in planta domain-switch analysis by replacing the C-terminal domain of AtNHX1 with a C-terminal segment of PeNHX3 containing the TM11 domain. We demonstrated that TM11 was critical for the Na+ and Li+ transport activities by PeNHX3. Taken together, PeNHX3 plays an important role in salt tolerance and Li+ detoxification in plants. TM11 controls the Na+ and Li+ transport activities of PeNHX3 in Arabidopsis.

Breeder reactors are considered as a unique tool for fully exploiting natural resources. Fast breeder reactors based on thorium fuel can enhance inherent safety. Fluoride salt has good performance as a coolant in high-temperature nuclear systems. However, there is some doubt about the fuel breeding ability using fluoride salt coolant for fast spectrum due to its moderating ability. The aim of this study was to choose a proper fluoride salt mixture for Liquid-salt-cooled Solid-fuel Fast Reactor (LSFR) based on thorium-uranium fuel and give parametric studies to provide a design window for flexible self-sustaining core design. Infinite assembly model was used to analyze the salt selection from five candidate fluorides for fast spectrum as coolant. Combining neutron balance analysis with linear least squares fitting method based on 0D model, parametric studies at the neutron balance equation unique solution with burn-up for several parameters such as fuel volume fraction, removing fission gases process, total neutron losses and power density were presented in this paper. It was found that BeF 2 -NaF was a promising coolant in the five candidate fluoride salt mixture. This study proved that the design of a self-sustaining core for fluoride-salt-cooled fast breeder based on thorium fuel is achievable. A design window was found in the definition of a self-sustaining core for various fuel volume fractions and neutron loss fractions. Core design and fuel management strategy will be given in future.

Background: Influenza infection was a vital threat to immunosuppressed patients with longer viral shedding; however, data on these populations in China are still lacking. We analyzed clinical characteristics, risk factors for admission to intensive care unit (ICU) and death, and effect of antiviral therapy in these populations.Methods: We analyzed 73 immunosuppressed inpatients tested positive for influenza virus using reverse-transcription polymerase chain reaction during the 2018-2019 influenza season. Medical data were analyzed using descriptive statistics. Univariate analysis and multivariate logistics analysis were used to identify risk factors. Results: The most common immunosuppression type was malignancies with chemotherapy 73.9% (54/73), then hematopoietic stem cell transplantation 19.2% (14/73). The most common presenting symptom was fever in 91.8% (67/73) patients, then cough 59.6% (34/57) and muscular soreness 35.1% (20/57). Complications and co-infections were found in 38.4% (28/73) and 17.8% (13/73) patients respectively, which significantly prolonged the hospital stay. Antiviral treatment after 48 hours was significantly associated with admission to ICU, mechanical ventilation and death. Combination and double dose of neuraminidase inhibitors did not significantly reduce the admission to ICU and death. 15.1% (11/73) patients were admitted to ICU and 8.2% (6/73) patients died. Risk factors for admission to ICU were long symptom onset (OR 5.60, P=0.018) and co-infection with other infections (OR 68.66, P=0.019), and presence of dyspnea was independently associated with death (OR 48.00, P=0.003) through multivariate logistics analysis. Seasonal influenza vaccination in preceding 12 months only took up 2.7% (2/73).Conclusion: Fever and other classical symptoms may be absent in immunosuppressed recipients, and conducting influenza virus detection at the first time is a good choice for early diagnosis. Antiviral treatment within 48 hours is of significance; however, patients may not benefit from combination and double dose of neuraminidase inhibitors. Immunosuppressed patients with dyspnea, long symptom onset and co-infection with other infections are of note needed, because these people have high-risk to severe cases. Inactivated influenza vaccination should be taken into account in immunosuppressed patients.

In this study, a numerical flow model of the fission products (FPs) in the primary loop system of a molten salt reactor (MSR) was established and solved using Mathematica 7.0. The simulation results were compared with those of the ORIGEN-S program in the static burnup mode, and the deviation was found to be less than 10%, which indicates that the results are in good agreement. Furthermore, the FPs distribution in the primary loop system under normal operating conditions of the 2 MW MSR was quantitatively analyzed. In addition, the distribution phenomenon of the FPs under different flow rate conditions was studied. At the end of life, the FPs activity in the core region (including active region, and upper and lower plenum regions) accounted for 77.3%, and that in the hot leg #1, main pump, hot leg #2, heat exchanger, and cold leg region accounted for 1.2%, 16.15%, 0.99%, 2.5%, and 1.9%, respectively, of the total FPs in the primary loop under normal operating conditions. The proportion of FPs in the core decreased with the increase in flow rate in the range of 2.24–22,400 cm3 s−1. The established analytical method and conclusions of this study can provide an important basis for radiation safety design of the primary loop, radioactive source management design, thermal–hydraulic safety analysis, and radiochemical analysis of FPs of 2 MW MSRs.

Thermal neutron scattering data has an important influence on the calculation and design of reactor with a thermal spectrum. However, as the only liquid fuel in the Gen-IV reactor candidates, the research on the thermal neutron scattering effect of coolant and somewhat moderator FLiBe has not been carried out sufficiently either experimentally or theoretically. The effect of FLiBe thermal neutron scattering on reactivity of TMSR-LF (thorium molten salt reactor - liquid fuel), TMSR-SF (thorium molten salt reactor - solid fuel) and MSRE (molten salt reactor experiment) were investigated and compared. Results show that the effect of FLiBe thermal neutron scattering on reactivity depends to some extent on the fuel-graphite volume ratio of core. Calculations indicate that FLiBe thermal neutron scattering of MSRE (with the hardest spectrum) has the minimum effect of 41 pcm on reactivity, and FLiBe thermal neutron scattering of TMSR-SF (with the softest spectrum) has the maximum effect of -94 pcm on reactivity, and FLiBe thermal neutron scattering of TMSR-LF has an effect of -61 pcm on reactivity at 900 K.

A numerical simulation program for the dynamic distribution of krypton and xenon with flow and on-line removal function was established for primary loop system of molten salt reactor(MSR) Based on Mathe-matica7.0.The simulation results of the static burnup was compared with ORIGEN-S program, and the deviation is less than 10%, which is in good agreement.The distribution and dynamic characteristics of krypton and xenon in the primary loop system were analyzed under the flow regionalization and online removal model.The results show that,the static burnup model underestimates the total 135Xe activity about 6.61% in the system, and the total activity of krypton and xenon in the system is underestimated by about 1.46%.Under the maximum removal fraction, the total activity of krypton and xenon in the exhaust gas system is 1.84×1016Bq, of which 83mKr, 85mKr, 87Kr, 88Kr, 133Xe, 135Xe and 138Xe account for about 95.6%.The total activity of krypton and xenon in the primary loop system is 2.64×1014Bq, of which 138Xe, 135mXe, 134mXe, 87Kr and 83mKr account for about 93.6%.The numerical simulation method and the conclusion consistent with the actual physical laws.Dynamic distribution, evolution and migration characteristics of krypton, xenon and these precursor in the primary loop in the molten salt can be simulated more accurately compared to static burnup model.The analysis results can provide a theoretical basis for the management scheme of airborne source termsthe cooling design of the radioactive exhaust system and the source term analysis in accident conditions for the molten salt reactor.

Source term analysis not only can provide the fundamental data for radiation shielding design, but also has a guiding significance for in-service inspection of the reactor. A numerical analysis model (MAST1.0) for activated products in the secondary loop system of the molten salt reactor (MSR) was developed. The deviation of the simulation results between MAST1.0 and ORIGEN-S are less than 7%, which indicates that they are in good agreements. The amounts of the activated products (16N, 20F and 19O) and the corrosion activated products (60Co, 55Fe, 54Mn, 51Cr, 59Ni, etc.) in the second loop were also obtained by MAST1.0, which show that the total activity of 16N, 20F and 19O is two orders of magnitude higher than that of the corrosion activated products in normal operating conditions. Flow rate has a significant effect on the distribution of 16N, 20F and 19O in the secondary loop. The total activity of 16N, 20F and 19O outside of the core increases monotonically with the increase of the flow rate. The concentration of 16N, 20F and 19O outside of the core tends to be stable, when the flow rate is greater than 1 × 106 cm3 s−1. Corrosion activated products show slowly increasing and decreasing trends in reactor startup and shutdown conditions, so they are the key radioactive sources for radiation protection after long-term shutdown of the reactor.

Producing medical radionuclide 99Mo in molten salt reactors is a very attractive choice to solve its global shortage. In this study, we evaluated the yield of 99Mo in the small modular thorium based molten salt reactor (SM-MSR). Firstly, the fuel burn-up analysis of SM-MSR was carried out by an in-house developed code (MOBAT), which takes the unique characteristics of molten salt reactor into account, and the variation of fission yield of 99Mo with burn-up time was obtained. The minimum value of the fission yield of 99Mo is 1.13 × 10−3 (6-day TBq/MW/s) at approximately 600 equivalent full power day. Then, based on the behavior of noble metals in the fuel salt and the experimental results of MSRE gas sample composition measurements, 99Mo migration probability from the primary loop to the off-gas module with the burn-up time was calculated, and the equilibrium value of the migration probability is obtained as 18.4%. When the load factor of SM-MSR is 0.75 (300 MWth), the annual 99Mo amount of migration to the off-gas module would be 1.96 × 106 (6-day TBq) under the most conservative calculation. Finally, a filter system was added in the off gas module, and 99Mo would be extracted from the off gas. As long as the utilization percentage of 99Mo in the off gas module can reach 0.94%, the global demand under current data could be met, which implies a huge additional economic value for the SM-MSR.

Delayed neutron loss is an important parameter in the safety analysis of molten salt reactors. In this study, to obtain the effective delayed neutron fraction under flow condition, a delayed neutron precursor transport was implemented in the Monte Carlo code MCNP. The molten-salt reactor experiment (MSRE) model was used to analyze the reliability of this method. The obtained flow losses of reactivity for 235U and 233U fuels in the MSRE are 223 pcm and 100.8 pcm, respectively, which are in good agreement with the experimental values (212 pcm and 100.5 pcm, respectively). Then, six groups of effective delayed neutron fractions in a small molten salt reactor were calculated under different mass flow rates. The flow loss of reactivity at full power operation is approximately 105.6 pcm, which is significantly lower than that of the MSRE due to the longer residence time inside the active core. The sensitivity of the reactivity loss to other factors, such as the residence time inside or outside the core and flow distribution, was evaluated as well. As a conclusion, the sensitivity of the reactivity loss to the residence time inside the core is greater than to other parameters.

The Molten Salt Reactor (MSR), the only one using liquid fuel in the six types ‘Generation IV’ reactors, is very different from reactors in operation now and has initiated very extensive interests all over the world. This paper is primarily aimed at investigating the breeding characteristics of high power (1000 MWe) Thorium Molten Salt Reactor (TMSR) based on the two-fluid Molten Salt Breeder Reactor (MSBR) with superior breeding performance. We explored the optimized structure to be a thorium based molten salt breeder reactor with different core conditions and different post-processing programs, and finally got the breeding ratio of 1.065 in our TMSR model. At last we analyzed the transient security of our optimized model with results show that the temperature coefficient of core is −3 pcm/K and a 2000 pcm reactivity insertion can be successfully absorbed by the core if the insertion time is more than or equal to 5 seconds and the core behaves safely.Copyright © 2017 by ASME

TMSR-LF1 (Thorium-based Molten Salt Reactor-Liquid Fuel) is the reactor chosen to be developed in the “Thorium molten salt reactor nuclear energy system” project of the Strategic Priority Program launched by the Chinese Academy of Sciences. The software and data library adopted in its design needs to be verified and validated by using benchmarks. In order to guarantee the validity of the verification results, the being-designed reactor should have similarity (index Ck and E ≥ 0.8) with the benchmark reactor. Using TSUNAMI module and in SCALE 6.1, the Sensitivity/Uncertainty (S/U) analyses and similarity assessments were performed in TMSR-LF1 and the candidate benchmark reactors: MSRE (Molten Salt Reactor Experiment), MSBR (Molten Salt Breeder Reactor) and the Critical Experiment Device (hereafter the device). Uncertainty was calculated using both SCALE and TMSR 44-group covariance data. It is found that the total eigenvalue uncertainties deduced from covariance data in TMSR-LF1 and the candidate benchmark reactors satisfy the ±1% design accuracy requirement proposed by M. Ishikawa in 2008, except in MSBR. To meet the accuracy of ±0.3%, targeted experiments for TMSR are needed. The covariance data of 7Li, C-graphite, 58Ni and 19F were the main contributors to the uncertainty of effective multiplication factor as well as the covariance data of fuel nuclides. The calculated similarity indices indicated that there was a good similarity (Ck and E > 0.9) between TMSR-LF1 and MSRE, and a lesser similarity between TMSR-LF1 and the device (Ck and E > 0.8). The uncertainties should be improved and more benchmarks for the direct verification and validation should be provided by relevant experiments.

This paper presents a neutronics design of a 10 MW ordered-pebble-bed fluoride-salt-cooled high-temperature experimental reactor. Through delicate layout, a core with ordered arranged pebble bed can be formed, which can keep core stability and meet the space requirements for thermal hydraulics and neutronics measurements. Overall, objectives of the core include inherent safety and sufficient excess reactivity providing 120 effective full power days for experiments. Considering the requirements above, the reactive control system is designed to consist of 16 control rods distributed in the graphite reflector. Combining the large control rods worth about 18000–20000 pcm, molten salt drain supplementary means (− 6980 to − 3651 pcm) and negative temperature coefficient (− 6.32 to − 3.80 pcm/K) feedback of the whole core, the reactor can realize sufficient shutdown margin and safety under steady state. Besides, some main physical properties, such as reactivity control, neutron spectrum and flux, power density distribution, and reactivity coefficient, have been calculated and analyzed in this study. In addition, some special problems in molten salt coolant are also considered, including 6Li depletion and tritium production.

The Molten Salt Reactor (MSR), the only one using liquid fuel in the six types ‘Generation IV’ reactors, is very different from reactors in operation now and has initiated very extensive interests all over the world. This paper is primarily aimed at investigating the breeding characteristics of high power (1000 MWe) Thorium Molten Salt Reactor (TMSR) based on the two-fluid Molten Salt Breeder Reactor (MSBR) with superior breeding performance. We explored the optimized structure to be a thorium based molten salt breeder reactor with different core conditions and different post-processing programs, and finally got the breeding ratio of 1.065 in our TMSR model. At last we analyzed the transient security of our optimized model with results show that the temperature coefficient of core is −3 pcm/K and a 2000 pcm reactivity insertion can be successfully absorbed by the core if the insertion time is more than or equal to 5 seconds and the core behaves safely.Copyright © 2017 by ASME