Search

Context Photosynthetic electron transport and apparatus are highly susceptible to abiotic stressors during photosynthesis. Hordeum jubatum L. is an ornamental grass with excellent salt tolerance, used for soil improvement and ecological restoration in Northeast China. However, the comparative effects of salt, alkali and drought conditions on the photosynthetic apparatus of H. jubatum under uniform water potential are little known. Aims We explored the photosynthetic response of H. jubatum to uniform levels of water potential stress induced by three different stressors: salt, alkali and drought. Methods Seedlings of H. jubatum were irrigated with three concentrations of NaCl, NaHCO3 and PEG-6000 to induce water potentials of −0.21, −0.47 and −0.82 MPa. Transient fluorescence of chlorophyll a in the seedlings was measured, and JIP-test parameters were obtained. Key results Lower values of J–I phase fluorescence intensity and appearance of a K-band under stress treatments indicated restricted electron transfer from the oxygen-evolving complex in the donor of photosystem II. In addition, the values of ΔI-band and parameters MO and N increased, whereas those of Sm, ϕEo and ψO decreased, indicating interruption of electron flow between electron acceptors pheophytin and NADP+. Serious adverse effects of alkali stress on the acceptors were observed; the low water potential induced by NaHCO3 damaged the thylakoid membrane on the chloroplast, resulting in increased degradation of D1 protein. Conclusions The results suggest that H. jubatum seedlings have greater tolerance to salt and drought stress, but are highly sensitive to alkali stress in the photosynthetic system. Implications This study provides physiological information for the successful cultivation of H. jubatum under adverse environment conditions.

The emerging low acidity in icewine grapes is becoming a major problem in producing quality icewine. Using non-Saccharomyces cerevisiae yeasts in fermentation can improve wine’s organoleptic characteristics and aromatic quality. This study evaluated two indigenous non-Saccharomyces cerevisiae yeasts, Lachancea thermotolerans (LT-2) and Torulaspora delbrueckii (TD-3), for their ability to improve the acidity and quality of ‘Semillon’ icewine. Five different inoculation schemes were implemented, including a single inoculation of S. cerevisiae (SC), L. thermotolerans (LT), and T. delbrueckii (TD); the sequential inoculation of L. thermotolerans, followed by S. cerevisiae after 6 days (L-S); and the sequential inoculation of L. thermotolerans, followed by T. delbrueckii after 6 days (L-D). The results showed that, during sequential fermentation (L-S and L-D), the presence of S. cerevisiae or T. delbrueckii slightly restrained the growth of L. thermotolerans. Single or sequential inoculation with L. thermotolerans and T. delbrueckii significantly reduced the amount of volatile acidity and increased the glycerol content. Furthermore, fermentations involving L. thermotolerans produced relevant amounts of lactic acid (2.04–2.2 g/L) without excessive deacidification of the icewines. Additionally, sequential fermentations increased the concentration of terpenes, C13-norisoprenoid compounds, and phenethyl compounds. A sensory analysis also revealed that sequentially fermented icewines (L-S and L-D) had more fruity and floral odors and aroma intensity. This study highlights the potential application of L. thermotolerans and T. delbrueckii in sequential fermentation to improve the icewine quality.

The chlorophyll ethanol-extracted silkworm excrement was hardly biologically reused or fermented by most microorganisms. However, partial extremely environmental halophiles were reported to be able to utilize a variety of inexpensive carbon sources to accumulate polyhydroxyalkanoates. In this study, by using the nile red staining and gas chromatography assays, two endogenous haloarchaea strains: Haloarcula hispanica A85 and Natrinema altunense A112 of silkworm excrement were shown to accumulate poly(3-hydroxybutyrate) up to 0.23 g/L and 0.08 g/L, respectively, when using the silkworm excrement as the sole carbon source. The PHA production of two haloarchaea showed no significant decreases in the silkworm excrement medium without being sterilized compared to that of the sterilized medium. Meanwhile, the CFU experiments revealed that there were more than 60% target PHAs producing haloarchaea cells at the time of the highest PHAs production, and the addition of 0.5% glucose into the open fermentation medium can largely increase both the ratio of target haloarchaea cells (to nearly 100%) and the production of PHAs. In conclusion, our study demonstrated the feasibility of using endogenous haloarchaea to utilize waste silkworm excrement, effectively. The introduce of halophiles could provide a potential way for open fermentation to further lower the cost of the production of PHAs.

Microbial biofilms are common on abiotic and biotic surfaces, especially in rivers, which drive crucial ecosystem processes. The microorganisms of biofilms are surrounded by a self-produced extracellular polymeric substance (EPS). In this study, we investigated the effects of different hydrodynamic conditions on the composition, spatiotemporal distribution of different extracellular polymeric substances, and the architecture of biofilms. Multidisciplinary methods offer complementary insights into complex architecture correlations in biofilms. The biofilms formed in turbulent flow with high shear force were thin but dense. However, the biofilms formed under laminar flow conditions were thick but relatively loose. The thickness and compactness of the biofilms formed in the transitional flow were different from those of the other biofilms. The compact structure of the biofilm helped to resist shear forces to minimize detachment. Under the turbulent flow condition, bacteria, exopolysaccharides, and extracellular proteins permeated through the biofilm, and more extracellular polysaccharides enveloped bacteria and extracellular proteins. However, under the transitional flow condition, the extracellular polysaccharides and proteins were fewer than those under the turbulent flow condition; bacteria and algae were seen more prominently in the upper layer of the biofilm. Under the laminar flow condition, the distribution of extracellular polysaccharides, extracellular proteins, and bacteria was relatively uniform throughout the biofilm. The number of extracellular polysaccharides was greater than that of extracellular proteins. The total number of EPS in the biofilm was the largest under turbulent flow condition, followed by that under transitional flow condition and then under laminar flow condition. This study also observed that soluble EPS (S-EPS) were secreted first, followed by loosely bound EPS (LB-EPS) and tightly bound EPS (TB-EPS). In particular, the adhesion of LB-EPS and flocculation capability of TB-EPS play some role in regulating biofilm formation. This study would help to perfect the five-stages theory of biofilm formation.

An efficient and regioselective C3-alkoxymethylation of indoles has been developed with aldehydes and alcohols via three-component cascade reaction under transition-metal free conditions. This method allows for rapid access to a variety of C3-alkoxymethylaed free (N-H) indole in up to 98% yield with excellent regioselectivity. The titled products are useful building blocks in organic synthesis.

Macrophages are important immune cells that participate in the regulation of inflammation in implant dentistry, and their activation/polarization state is considered to be the basis for their functions. The classic dichotomy activation model is commonly accepted, however, due to the discovery of macrophage heterogeneity and more functional and iconic exploration at different technologies; some studies have discovered the shortcomings of the dichotomy model and have put forward the concept of alternative activation models through the application of advanced technologies such as cytometry by time-of-flight (CyTOF), single-cell RNA-seq (scRNA-seq), and hyperspectral image (HSI). These alternative models have great potential to help macrophages divide phenotypes and functional genes.

Intrahepatic cholangiocarcinoma (ICC) is characterised by heterogeneity, and it can be subdivided into small-duct and large-duct types. Inflammatory and tumour markers could effectively predict prognosis in many cancers, but no similar studies have been conducted in the histological subtypes of ICC. A total of 102 and 72 patients with ICC undergoing curative-intent resection were retrospectively subclassified into large-duct and small-duct types by chemical staining, respectively. The prognostic value of inflammatory and tumour markers was studied for the first time in histological subtypes of ICC by using a Cox regression model. A novel predictor named prognostic inflammatory index (PII) was proposed and defined as neutrophil × monocyte / lymphocyte count (109/L). Survival analysis showed that PII, neutrophil-to-lymphocyte ratio (NLR), lymphocyte-to-monocyte ratio (LMR), carcinoembryonic antigen (CEA), carbohydrate antigen 19-9 (CA19-9), CA242, and ferritin were all predictors of DFS and OS in patients with ICC ( P < 0.040 ). Subgroup analysis showed that PII, CA19-9, and ferritin were risk predictors of disease-free survival (DFS) and overall survival (OS) in small-duct type ICC ( P < 0.015 ). In addition, in small-duct type ICC, NLR and LMR were correlated with OS ( P < 0.025 ), whilst CEA and CA242 were correlated with DFS ( P ≤ 0.010 ). In conclusion, PII is a convenient and efficient inflammatory predictor of DFS and OS in ICCs and their small-duct type. NLR and LMR, rather than platelet-to-lymphocyte ratio, were correlated with OS in small-duct type ICC. In addition, ferritin may be a supplement to CA19-9 in stratifying the survival outcome of patients with small-duct type ICC.

Heavy water-moderated molten salt reactors (HWMSRs) are novel molten salt reactors that adopt heavy water rather than graphite as the moderator while employing liquid fuel. Owing to the high moderating ratio of the heavy water moderator and the utilization of liquid fuel, HWMSRs can achieve a high neutron economy. In this study, a large-scale small modular HWMSR with a thermal power of 500 MWth was proposed and studied. The criticality of the core was evaluated using an in-house critical search calculation code (CSCC), which was developed based on Standardized Computer Analyses for Licensing Evaluation, version 6.1. The preliminary fuel cycle performances (initial conversion ratio (CR), initial fissile fuel loading mass, and temperature coefficient) were investigated by varying the lattice pitch (P) and the molten salt volume fraction (VF). The results demonstrate that the temperature coefficient can be negative over the range of investigated Ps and VFs for both 233U-Th and LEU-Th fuels. A core with a P of 20 cm and a VF of 20% is recommended for 233U-Th and LEU-Th fuels to achieve a high performance of initial CR and fuel loading. Regarding TRU-Th fuel, a core with a smaller P (~ 5 cm) and larger VF (~ 24%) is recommended to obtain a negative temperature coefficient.

The production capacity of

Objective: This study aimed to explore whether eukaryotic translation elongation factor 1 alpha 2 affected cell proliferation, migration, and apoptosis via regulating the dimethylation of eukaryotic translation elongation factor 1 alpha at lysine 55 in acute myeloid leukemia. Methods: The expressions of eukaryotic translation elongation factor 1 alpha 2 and dimethylation of eukaryotic translation elongation factor 1 alpha at lysine 55 in acute myeloid leukemia cell lines and human normal bone marrow mononuclear cells (as control) were assessed. Control CRISPR-Cas9 lentivirus, eukaryotic translation elongation factor 1 alpha 2 knockout CRISPR-Cas9 lentivirus, vector plasmid, eukaryotic translation elongation factor 1 alpha 2 wild type overexpression plasmid, and eukaryotic translation elongation factor 1 alpha 2 with a K55R substitution overexpression plasmid were transfected into AML-193 and Kasumi-1 cells combined or alone, and were accordingly divided into 4 groups (Sgcontrol + vector group, SgeEF1A2 + vector group, SgeEF1A2 + eEF1A2WT group, and SgeEFIA2 + eEF1A2K55R group). Results: Eukaryotic translation elongation factor 1 alpha 2 and dimethylation of eukaryotic translation elongation factor 1 alpha at lysine 55 expressions were higher in AML-193, Kasumi-1, and KG-1 cell lines compared to the control. In AML-193 and Kasumi-1 cells, the knockout and compensated experiments revealed that eukaryotic translation elongation factor 1 alpha 2 promoted cell proliferation and migration but repressed apoptosis. Additionally, the knockout of eukaryotic translation elongation factor 1 alpha 2 decreased dimethylation of eukaryotic translation elongation factor 1 alpha at lysine 55 expression, meanwhile, eukaryotic translation elongation factor 1 alpha 2 wild type overexpression enhanced while eukaryotic translation elongation factor 1 alpha 2 with a K55R substitution overexpression did not influence the dimethylation of eukaryotic translation elongation factor 1 alpha at lysine 55 expression. Furthermore, eukaryotic translation elongation factor 1 alpha 2 wild type overexpression promoted cell proliferation, enhanced migration, and decreased apoptosis, but eukaryotic translation elongation factor 1 alpha 2 with a K55R substitution overexpression did not influence these cellular functions in AML-193 and Kasumi-1 cells, suggesting the implication of dimethylation of eukaryotic translation elongation factor 1 alpha at lysine 55 in eukaryotic translation elongation factor 1 alpha 2 mediated oncogenesis of acute myeloid leukemia. Conclusion: Eukaryotic translation elongation factor 1 alpha 2 and its dimethylated product may serve as therapeutic targets, and these findings may provide support for exploring novel strategies in acute myeloid leukemia treatment.

A Channel-type Molten Salt Fast Reactor (CMSFR) concept is studied to improve the Th-U breeding performance and to reduce the loss ratio of effective delayed neutron fraction (βeff). In the CMSFR, fuel salt is filled in the active zone of the cylindrical core for fission heat generation, while fertile salt is contained in SiC tubes distributed regularly in the core for 233U breeding and for transferring fission heat from the fuel salt to the secondary loop. To enhance the neutron capture reaction rate of 232Th, both radial and axial Th fertile blankets are adopted. Only a small part of fuel salt in the reprocessing system is adopted for fission products removing and refueling, which reduces significantly the required initial loading of fuel salt compared with a conventional Molten Salt Reactor (MSR). Based on an in-house developed analysis code for reprocessing system of MSR, the Th-U breeding capability of CMSFR with different molten salt reprocessing rates (from 10 l per day to 50 l per day) is simulated for a 50-year operation. The simulated results show that the doubling time of 233U with 233U as starting fuel shortens significantly to about 37 years compared with the Molten Salt Fast Reactor (MSFR). Furthermore, the Th-U breeding capability with Pu, TRU and Low Enriched Uranium (LEU) as starting fuels is also analyzed. The simulated results indicate that the doubling time of 233U with Pu and TRU as starting fuels is shortened to 22 years and 17 years, respectively. It indicates that both Pu and TRU can be employed for a transition approach to Th-U fuel cycle. The largest molar proportion of Pu with TRU as starting fuel during operation is about 7.1 mol% which is under the Pu solubility limit. Although the Th-233U breeding with LEU as starting fuel can also be achieved at the end of life of operation, it needs external 233U supply (about 0.6 tons) during the first 20 years operation. Both Temperature Reactivity feedback Coefficient (TRC) and βeff for all the starting scenarios are also investigated. The TRC for all the starting scenarios is always negative enough during 50-year operation. The total loss ratio of βeff with 233U, LEU and Pu/TRU as starting fuels is only 13.76%, 13.47% and 13.56%, respectively, which is much smaller than that of the MSFR. Considering the limitation of reactor period T > 15 s, the largest introduced reactivity for 233U, LEU or Pu/TRU as starting fuel shall not be greater than 110 pcm, 202 pcm and 103 pcm, respectively.

In this work, a novel organic-inorganic hybrid nanoflower was synthesized by the incorporation of glucose oxidase and lipase and used as the coimmobilized enzyme in the epoxidation of alkenes. Imaging and catalytic performance results suggest that the dual-enzyme nanoflower greatly reduces the diffusion and decomposition of H 2 O 2 and facilitates the mass transfer of glucose oxidase/lipase. Furthermore, the controllable generation of H 2 O 2 and peracid contributes to the good stability of the dual-enzyme nanoflower, which exhibits a higher catalytic performance than the free enzymes in a dual-enzymatic cascade epoxidation. The yield of epoxidation was up to 82% even after ten cycles, further indicating the good reusability of the dual-enzyme nanoflower and its great potential for application in other enzymatic oxidations.

Compared with the well-studied neutron poison 135 Xe, 149 Sm received much less attention in the conventional reactors because of the comparatively smaller neutron absorption cross section. But in Molten Salt Reactor (MSR), gaseous fission products such as xenon and krypton are largely removed by the gas removal system, the behavior of 149 Sm, which exists in molten salt, therefore becomes important. During MSR’s operation, the liquid fuel continuously circulates through the core (with neutron flux functioning) and outer-loop (the part of primary loop at external core, with negligible neutron flux), the nuclide evolution law is much different from that in the solid fueled reactors, thereby accurately evaluating the time behavior of 149 Sm is much needed. In this work, the control equations precisely describing the nuclide evolution of 149 Sm as well as its precursor 149 Pm entrained in the flowing salt are deduced, and a time behavior during different power cycles is then investigated for a small modular molten salt reactor based on the deduced equations. To fundamentally understand the flow effect on 149 Sm time behavior, the corresponding results are compared with those calculated by using the existent method, in which the flowing fuel is treated as the static fuel. Because the disappeared 149 Pm regardless at the core and outer-loop is all converted to 149 Sm, the flow state has a same equilibrium atomic density with that at the static state. But the time for achieving the equilibrium at the flow state is prolonged due to the time for 149 Pm decayed to 149 Sm being extended at a same 149 Pm production rate. This effect also leads to a lower “samarium peaking (overshoot)” for power up/down, as well as a lower 149 Sm concentration after scram which subsequently decreases the neutron poison (around 210 pcm) as the core start-up again. This work provides a precise description for the evolution of 149 Sm for circulating fuel, which should be included in the core design and source term analysis of safety study of a MSR.

A novel ratiometric fluorescence and colorimetric probe (BDT-PBES) based on benzo[1,2-b:4,5-b’]dithiophene (BDT) unit, for the detection of Hg2+, was developed with dithioacetal group as the response unit. Based on the Hg2+-promoted dithioacetal deprotection reaction mechanism, the probe displayed high selectivity for Hg2+ over other ions including Co2+, Mn2+, Zn2+, Ag+, Cd2+, Pb2+, Ca2+, Al3+, Cr3+, Na+, Cu2+, Mg2+, Ni2+, K+, Fe2+, Pd2+ and Fe3+. The detection limit reached as low as 3.1 × 10–7 M. When Hg2+ existed, the maximum absorption peaks were obviously red-shifted with a solution color change from clarifying to light yellow, and the fluorescence changed with a large Stokes shift (179 nm) from blue-green to yellow.

The production capacity of 89Sr and 90Sr in the 2 MW MSR are evaluated. The gaseous 89Kr and 90Kr are extracted from the core through the helium bubbling system, and then decay to 89Sr and 90Sr, respectively. In order to improve purity of 89Sr product, two cooling devices are adopted in the 89Sr and 90Sr production system. The annual yields of 89Sr and 90Sr are about 9000 Ci and 32 Ci, respectively, and the impurity of 89Sr product is less than 2 ppm which can meet the medical requirement.

A new dual chemosensor ( TTF-PBA ) for Fe 3+ and Cu 2+ in different signal pathways was designed and synthesized. The absorption spectrum, fluorescence spectrum and cyclic voltammograms changed in the presence of Cu 2+ and Fe 3+ . The optical color changed within 5 s from yellow to orange upon the addition of Cu 2+ , and it changed to dark yellow when Fe 3+ existed. The cyclic voltammogram of Cu 2+ /TTF-PBA changed from E ox = 0.50 V, E red = 0.32 V to E ox = 0.64 V, E red = 0.80 V ( vs Ag/AgCl) upon the addition of 2.0 equiv. Cu 2+ . As for Fe 3+ /TTF-PBA, its oxidation wave disappeared, and its reduction wave appeared at E red = −0.59 V ( vs Ag/AgCl) upon the addition of 4.0 equv. Fe 3+ . The sensor displayed high selectivity for Cu 2+ and Fe 3+ over other ions including Pb 2+ , Zn 2+ , Ni 2+ , Ag + , Cr 3+ , Mn 2+ , Al 3+ , Co 2+ , Pd 2+ , Hg 2+ , Fe 2+, Cd 2+ , Ce 3+ , Bi 3+ and Au 3+ , the detection limits for Cu 2+ and Fe 3+ ion reached as low as 5.33 × 10 −7 mol/L and 5.34 × 10 −7 mol/L, respectively. Furthermore, when Fe 3+ existed, Cu 2+ can be detected sequentially by the sensor through the absorption spectrum and the color change observed by naked-eyes.

Minor actinide (MA) accumulated in spent fuel is the primary contributor to the long-term radiological hazards of high-level nuclear waste. Due to its outstanding features such as fast neutron spectrum, no fuel assembly fabrication, on-line refueling and reprocessing, Molten Salt Fast Reactor (MSFR) is regarded as one of the candidate reactors for MA incineration. In the present work, we evaluate the MA incineration capability for a 500 MWth FLiNaK MSFR by considering on-line MA feeding into the fuel salt and/or 233 U extraction from the fertile salt, where the initial FLiNaK fuel salt is composed of 70 mol% (LiF, NaF and KF) and 30 mol% (ThF 4 , 233 UF 4 and MAF 3 ). The simulated results show that, during a 50-year operation, the MA incineration efficiency with on-line MA feeding and 233 U extraction scenario is significantly higher compared with the case without either MA feeding or 233 U extraction. Based on the scenario of on-line MA feeding and 233 U extraction, the initial MA loading is further adjusted to keep a small excess reactivity during the whole operation. And the MA incineration amount, the depletion ratio between MA and total heavy nuclides and the MA incineration efficiency at 50-year operating time are 7301 kg, 77.4% and 33.3 kg/TWh, respectively, with a doubling time of 39-year for 233 U breeding. We also analyze and discuss the evolutions of the fuel temperature feedback coefficient, the effective delayed neutron fraction and the intensity of spontaneous fission neutron during the whole operating time.

To optimize the temperature coefficient of reactivity (TCR) for a graphite-moderated and liquid-fueled molten salt reactor, the effects of fuel salt composition on the fuel salt temperature coefficient of reactivity (FSTC) were investigated in our earlier work. In this study, we aim to provide a more comprehensive analysis of the TCR by considering the effects of the graphite-moderator temperature coefficient of reactivity (MTC). The effects of $$^{235}$$U enrichment and heavy metal (HM) proportion in the salt mixture on the MTC are investigated from the perspective of the six-factor formula based on a full-core model. For the MTC (labeled “$$\alpha _{{\mathrm{TM}}}$$”), the temperature coefficient of the fast fission factors ($$\alpha _{{\mathrm{TM}}}(\varepsilon )$$) is positive, while those of the resonance escape probability ($$\alpha _{{\mathrm{TM}}}(p )$$), the thermal reproduction factor ($$\alpha _{{\mathrm{TM}}}(\eta )$$), the thermal utilization factor ($$\alpha _{{\mathrm{TM}}}(f )$$), and the total non-leakage probability ($$\alpha _{{\mathrm{TM}}}(\varLambda )$$) are negative. The results reveal that the magnitudes of $$\alpha _{{\mathrm{TM}}}(\varepsilon )$$ and $$\alpha _{{\mathrm{TM}}}(p )$$ for the MTC are similar. Thus, variations in the MTC with $$^{235}$$U enrichment for different HM proportions are mainly dependent on $$\alpha _{{\mathrm{TM}}}(\eta )$$, $$\alpha _{{\mathrm{TM}}}(\varLambda )$$, and $$\alpha _{{\mathrm{TM}}}(f )$$, but especially on the former two. To obtain a more negative MTC, a lower HM proportion and/or a lower $$^{235}$$U enrichment is recommended. Together with our previous studies on the FSTC, a relatively soft neutron spectrum could strengthen the TCR with a sufficiently negative MTC.

The solid fuel thorium molten salt reactor (TMSR-SF1) is a 10-MWth fluoride-cooled pebble bed reactor. As a new reactor concept, one of the major limiting factors to reactor lifetime is radiation-induced material damage. The fast neutron flux (E > 0.1 MeV) can be used to assess possible radiation damage. Hence, a method for calculating high-resolution fast neutron flux distribution of the full-scale TMSR-SF1 reactor is required. In this study, a two-step subsection approach based on MCNP5 involving a global variance reduction method, referred to as forward-weighted consistent adjoint-driven importance sampling, was implemented to provide fast neutron flux distribution throughout the TMSR-SF1 facility. In addition, instead of using the general source specification cards, the user-provided SOURCE subroutine in MCNP5 source code was employed to implement a source biasing technique specialized for TMSR-SF1. In contrast to the one-step analog approach, the two-step subsection approach eliminates zero-scored mesh tally cells and obtains tally results with extremely uniform and low relative uncertainties. Furthermore, the maximum fast neutron fluxes of the main components in TMSR-SF1 are provided, which can be used for radiation damage assessment of the structural materials.

A novel turn-off probe for copper(II) containing benzo[1,2-b:4,5-b′]dithiophene (BDT) and two picolinamide units was synthesized. In this probe, two picolinamide units complex with one Cu2+ ion and two nitrogen atoms in each picolinamide unit coordinate with Cu2+, which is verified by DFT calculation. Its fluorescence quantum yield is 0.43 and the detection limit is as low as 2.4×10−8 mol/L. The results show that the probe displays good selectivity for Cu2+ over other ions (Mn2+, Pb2+, Cr3+, Zn2+, Ni2+, K+, Ca2+, Ag+, Mg2+, Fe3+, Fe2+, Hg2+, Al3+, Cd2+, Pd2+, Co2+). Furthermore, the probe induced by Cu2+ and the π–π interaction of the aromatic unit can also form rod structure assembly, which can be observed by scanning electron microscopy (SEM).

With respect to a liquid-fueled molten salt reactor (MSR), the temperature coefficient of reactivity mainly includes the moderator temperature coefficient (MTC) and the fuel salt temperature coefficient (FSTC). The FSTC is typically divided into the Doppler coefficient and the density coefficient. In order to compensate for the potentially positive MTC, the FSTC should be sufficiently negative, and this is mostly optimized in terms of the geometry aspect in pioneering studies. However, the properties of fuel salt also directly influence the FSTC. Thus, the effects of different fuel salt compositions including the $$^{235}$$ U enrichment, heavy metal proportion in salt phase (HM proportion), and the $$^{7}$$ Li enrichment on FSTC are investigated from the viewpoint of the essential six-factor formula. The analysis is based on an under-moderated MSR. With respect to the Doppler coefficient, the temperature coefficient of the fast fission factors ( $$\alpha _{\text {T}}(\varepsilon )$$ ) is positive and those of the resonance escape probability ( $$\alpha _{\text {T}}(p )$$ ), thermal reproduction factor ( $$\alpha _{\text {T}}(\eta )$$ ), thermal utilization factor ( $$\alpha _{\text {T}}(f )$$ ), and total non-leakage probability ( $$\alpha _{\text {T}}(\varLambda )$$ ) are negative. With respect to the density coefficient, $$\alpha _{\text {T}}(p )$$ and $$\alpha _{\text {T}}(\eta )$$ are positive, while the others are negative. The results indicate that the effects of the $$^{235}$$ U enrichment and HM on FSTC are mainly reflected in $$\alpha _{\text {T}}(\varepsilon )$$ and $$\alpha _{\text {T}}(p )$$ , which are the dominant factors when the neutron spectrum is relatively hard. Furthermore, the $$^{7}$$ Li enrichment influences FSTC by $$\alpha _{\text {T}}(f )$$ and $$\alpha _{\text {T}}(\varLambda )$$ , which are the key factors in a relative soft spectrum. In order to obtain a more negative FSTC for an under-moderated MSR, the possible positive density coefficient, especially its $$\alpha _{\text {T}}(p )$$ , should be suppressed. Thus, a lower $$^{235}$$ U enrichment (albeit higher than a certain value, 5 wt% in this article) along with a lower HM proportion and/or a higher $$^{7}$$ Li enrichment are recommended. The analyses provide an approach to achieve a more suitable fuel salt composition with a sufficiently negative FSTC.

This paper reports the self-assembly of two new tetrathiafulvalene (TTF) derivatives that contain one or two urethane groups. The formation of nanoribbons was evidenced by scanning electron microscopy (SEM) and X-ray diffraction (XRD), which showed that the self-assembly ability of T1 was better than that of T2. The results revealed that more urethane groups in a molecule did not necessarily instigate self-assembly. UV–vis and FTIR spectra were measured to explore noncovalent interactions. The driving forces for self-assembly of TTF derivatives were mainly hydrogen bond interactions and π–π stacking interactions. The electronic conductivity of the T1 and T2 films was tested by a four-probe method.

General Atomics (GA) is developing the Energy Multiplier Module (EM2) which is a compact gas-cooled fast reactor as one of candidates of the Generation-IV nuclear energy systems. In the EM2 core, low enriched uranium is used as igniting fuel and depleted uranium is used for converting and burning. It indicates that EM2 can maintain critical operation for more than 30 years without refueling. To further study the Th-U fuel cycle performance in the EM2, two kinds of start-up strategies with Th-U (Th + U-233) and semi Th-U (Th + enriched U-235) are evaluated. Neutronics characteristics, such as the effective multiplicity factor (k(eff)) and conversion ratio (CR) are analyzed from neutron usage point of view. The simulated results for the two kinds of fuels are compared with the U-Pu fuel from the design of GA. The analysis gives an insight into the pros and cons of U-Pu and Th-U fuel cycles in terms of the breeding capability and the discharged radio-toxicity. The breeding performance of the second generation EM2 is also presented and compared with that of the first generation EM2. It indicates that the multi-generation EM2 can deepen the burnup and reduce the waste management pressure for each kind of fuel loading strategy. (C) 2015 Elsevier Ltd. All rights reserved.

The in situ breed-and-burn (B&B) strategy in fast reactor is capable of offering very high fuel utilization efficiency. CANDLE (Constant Axial shape of Neutron flux, nuclide densities and power shape During Life of Energy) or TWR (Traveling Wave Reactor) is a possible scheme to implement the B&B strategy. The approach in realizing the equilibrium state of CANDLE is based on neutron source supply from ignition zone with enriched uranium or plutonium. And burnable poison is usually employed to compensate the extremely high excess reactivity during the startup. In the present work, the optimization of the starter fuel with only plutonium and depleted uranium is performed to reduce the initial positive excess reactivity swing and to flatten the power distribution. The optimization is done with refer to a nominal steady state CANDLE core. In this regard the swing of the reactivity is limited during the startup. And the initial power shape is flattened significantly compared with that without optimization. It is proved that constructing the ignition zone with refer to the equilibrium state of a CANDLE is effective and feasible to improve the operation performance during the startup. (C) 2015 Elsevier Ltd. All rights reserved.

Two novel donor-π-acceptor chemosensors, exTTF-DPA and exTTF-ADPA, based on π-extended tetrathiafulvalene (exTTF) and di(pyridine-2-ylmethyl)amine (DPA) were synthesized and used as optical and electrochemical chemosensors for copper(II). The results showed that they possess specific selectivity for copper(II) in the presence of other competing metal ions (Zn2+, Sn2+, Pb2+, Pd2+, Hg2+, Al3+, Fe3+, Ag+, Co2+, Ni2+) in acetonitrile. Upon the addition of Cu2+, the solution color changed from yellow to orange, the cyclic voltammograms changed dramatically and the fluorescence quenched completely.

As one of the six candidate reactors chosen by the Generation IV International Forum (GIF), Molten Salt Fast Reactor (MSFR) has many outstanding advantages and features for advanced nuclear fuel utilization. Effective transmutation of minor actinides (MA) could be attained in this kind of fast reactor, which is of importance in the future closed nuclear fuel cycle scenario. In this work, we attempt to study the MA transmutation capability in a MSFR with power of 500 MWth by analyzing the neutronics characteristics for different MA loadings. The calculated results show that MA loading plays an important role in the reactivity evolution of the MSFR. A larger MA loading is favorable to improving the MA transmutation performance and simultaneously to reducing the fissile consumption. When MA = 18.17 mol%, the transmutation fraction can achieve to about 95% on iso-breeding. We also find that although the fuel temperature coefficient (FTC) decreases with the increasing MA loading, it is still negative enough to keep the safety of the MSFR during the whole operation time. The MA contribution to the effective delayed neutron fraction (EDNF) and the intensity of spontaneous fission neutron (ISFN) are also analyzed. Also MA loading can affect the EDNF during the operation and the ISFN of the MSFR is dominated by (CM)-C-244. Finally, we analyze the effect of the core power on MA transmutation capability. The result shows that for all the operating powers the depletion ratio of MA to HN increases with time and reaches a maximum value. And additional MA should be fed into the fuel salt before the MA depletion ratio reaches the peak value to improve its transmutation capability. The net mass of the transmuted MA during the 50 years operation for 500 MWth is 5620 kg which is very close to that of 1000 MWth. (C) 2015 Elsevier Ltd. All rights reserved.

A series of new A–π–D–π–A molecules including diphenylamine and carbazole had been synthesized and characterized ( T1 – T3 ). T1 and T2 displayed aggregation-induced emission enhancement (AIEE): exhibiting weak fluorescence in pure THF, which a signification AIEE effect was observed in mixture with a water fraction ( f w ) of 90% with a sharp increase in fluorescence intensity. T3 displayed aggregation-caused quenching (ACQ): exhibiting strong fluorescence in pure THF, which a signification ACQ effect was observed in mixture with a water fraction ( f w ) of 90% with a sharp decrease in fluorescence intensity. Their two-photon absorption (2PA) had been investigated using the open-aperture Z-scan technique, and the values of the 2PA cross section at 800 nm for T1 – T3 were 1115, 681, in chloroform, respectively.

Molten salt reactor (MSR) has fascinating features: inherent safety, no fuel fabrication, online fuel reprocessing, etc. However, the graphite moderated MSR may present positive feedback coefficient which has severe implications for the transient behavior during operation. In this paper, the feedback coefficient and the breeding ratio are optimized based on the fuel-to-graphite ratio variation for a thorium based MSR (TMSR). A certain thermal core with negative feedback coefficient and relative high initial breeding ratio is chosen for the reprocessing scheme analysis. The breeding performances for the TMSR under different online fuel reprocessing efficiencies and frequencies are evaluated and compared with other MSR concepts. The results indicate that the thermal TMSR can get a breeding ratio greater than 1.0 with appropriate reprocessing scheme. The low fissile inventory in thermal TMSR leads to a short doubling time and low transuranic (TRU) inventory. The lifetime of graphite used for the TMSR is also discussed. (C) 2014 Elsevier B.V. All rights reserved.

In order to utilize thorium in Fluoride salt-cooled High-temperature Reactor (FHR), neutronics analysis for thorium based fuels (U-233 + Th, U-235 + Th and Pu-239 + Th) is carried out in a whole-core model of pebble bed FHR. Uranium (U-239) based fuels with the above three fissile nuclides are also analyzed for comparison. The atomic density of fissile material is kept constant at start-up for the six fuel types. Neutron characteristics including neutron spectrum, effective multiplicity factor (k(eff)), temperature coefficient of reactivity (TCR), conversion ratio (CR) and burnup for the six fuel options are discussed. With the same fissile nuclide, the thorium based fuels have a higher initial k(eff) than the uranium based fuels due to the smaller resonance absorption of Th-232. As for fissile material, U-233 is the best candidate as a driver fuel in thermal and epithermal spectra due to its effective number of fission neutrons (eta). Besides, the Th-232/U-233 fuel can be extended to radioactive waste management benefited from deeper burnup and lower level of radio-toxicity. The FHR core with thermal and epithermal spectra is more suitable for Th-U fuel cycle than U-Pu fuel cycle. These analyses can provide an approach for the further optimizations of thorium utilization in FHR. (C) 2014 Elsevier Ltd. All rights reserved.