A 0.35 THz Extended Interaction Oscillator based on Overmoded and Bi-Periodic Structure

An improved topology of Extended interaction oscillators (EIO) is presented with enhanced efficiency at 0.35 THz. A bi-periodic ladder-type structure is used for optimizing the performance of the TM 31−2π mode operation, based on bi-periodic interaction gaps composed of staggered short and long slots. The bi-periodic interaction mechanism permits to operate the circuit with a standing-wave field between the π and 2π modes, thus providing the potential to combine the advantages of both π and 2π modes in terms of both coupling and output performance. The resulting transverse TM 31 operating mechanism exhibits a good agreement with the bi-periodic structure in terms of coupling performance, with the short slot length positively correlated with the value of effective characteristic impedance M2R/Q . The circuit demonstrates attractive coupling and output characteristics by optimization of M2R/Q and Qe . A state-of-the-art value M2R/Q of 59.69 Ω and a moderate Qe of 2523.52 are achieved for a proposed eight-period ladder-type EIO. An RF power of 540 W is obtained with a 42.5 kV, 0.6 A sheet beam, with 2.1% electronic efficiency at 0.35 THz

Development and verification of lead-bismuth cooled fast reactor calculation code system Mosasaur

Lead-bismuth cooled fast reactor calculation code system named MOSASAUR has been developed to meet the simulation requirements from LBFR engineering design. An overview of MOSASAUR developments is provided in this paper, four main functional modules and their models are introduced: cross-sections generation module, flux spectrum correction module, core simulation module and sensitivity and uncertainty analysis module. Verification and validation results of numerical benchmark calculations, code-to-code comparisons with the Monte-Carlo code and critical experimental calculations shown in this paper prove the capabilities of MOSASAUR in dealing with lead-bismuth cooled fast reactor analysis problems with good performances. Numerical results demonstrate that compared with the Monte-Carlo code, the relative errors of eigenvalues are smaller than 350pcm when the calculations were carried out with the same nuclear data file. Compared with the measured values, the errors will increase due to the simulation details and the measurement accuracy

Optimization of conceptual design on the lead-based modular nuclear power reactor core loaded with U-10Zr alloy fuel

As one of the forth-generation nuclear energy system reactor types, lead fast reactor has good safety and economical properties due to the stable chemical properties of the coolant and the proliferation characteristics of the fuel, and modular nuclear power faster reactor designed for nuclear plant can further improve the economics of the reactor. In this article, the conceptual design of the lead-based modular power reactors with different power levels loaded with uranium alloy fuel is found to be found that when reactor core size increased to a certain level, the proliferation performance is too high due to the increase of the reactor core size under a specific core life such as 2000EFPD, so at the end of core life, the reactor core still has a large remaining reactivity. The proliferation advantage of the core cannot be fully released during the current core life time. Based on this phenomenon, in this article, we optimized the conceptual design of lead-based modular nuclear power reactor core loaded with uranium alloy fuel, and proposed to choose the appropriate rod to diameter ratio and effective density of fuel based on the power level and life time of the core. By adjusting the amount of uranium and 235U per unit volume, the proliferation performance of the core can be changed to match the power level and life time of the core. So the reactivity of core during the life period does not change, which not only reduce the difficulty of the reactivity control, but also make full use of the proliferation performance of the core. And at the same time, the reasonable rod to diameter ratio can provide safety and design margin for the analysis of thermal and hydraulic safety, and effectively improve the economy and safety of the core

Effect of austenitizing temperature on the bainitic transformation in a high-carbon high-silicon steel

The effect of austenitizing temperature (880 - 1000°C) on the incubation period and bainitic transformation in steel 0.88% C - 1.35% Si - 1.0% Cr - 0.43% Mn is studied by the methods of x-ray diffraction and optical and transmission electron microscopy. The effect of the austenitizing temperature on the temperature and incubation period of the nose of the C-curve of the bainitic transformation is determined. The influence of a 20-min hold at 250°C after the austenitizing on the bainitic structure is studied

A Single-domain Protein Catenane of Dihydrofolate Reductase

A single-domain protein catenane refers to two mechanically interlocked polypeptide rings that fold synergistically into a compact and integrated structure, which is extremely rare in nature. Herein, we report a single-domain protein catenane of dihydrofolate reductase (cat-DHFR). The design was achieved by rewiring the connectivity between secondary motifs to introduce artificial entanglement and the synthesis was readily accomplished by a series of programmed streamlined post-translational processing events in cells without any additional in vitro reactions. The target molecule contains few exogenous motifs and has been thoroughly characterized by combined techniques of LC-MS, SDS-PAGE, protease cleavage experiment, and ion mobility mass spectrometry. Compared to the linear control, cat-DHFR retains the catalytic capability and exhibits enhanced stability against thermal or chemical denaturation due to conformational restriction. The results suggest that linear proteins may be converted into concatenated single-domain counterparts with almost identical chemical composition, well-preserved function, and elevated stability, which represents an entirely new horizon in protein science

The Spatiotemporal Expression of Notch1 and Numb and Their Functional Interaction during Cardiac Morphogenesis

Numb family proteins (NFPs), including Numb and Numblike (Numbl), are commonly known for their role as cell fate determinants for multiple types of progenitor cells, mainly due to their function as Notch inhibitors. Previous studies have shown that myocardial NFP double knockout (MDKO) hearts display an up-regulated Notch activation and various defects in cardiac progenitor cell differentiation and cardiac morphogenesis. Whether enhanced Notch activation causes these defects in MDKO is not fully clear. To answer the question, we examined the spatiotemporal patterns of Notch1 expression, Notch activation, and Numb expression in the murine embryonic hearts using multiple approaches including RNAScope, and Numb and Notch reporter mouse lines. To further interrogate the interaction between NFPs and Notch signaling activation, we deleted both Notch1 or RBPJk alleles in the MDKO. We examined and compared the phenotypes of Notch1 knockout, NFPs double knockout, Notch1; Numb; Numbl and RBPJk; Numb; Numbl triple knockouts. Our study showed that Notch1 is expressed and activated in the myocardium at several stages, and Numb is enriched in the epicardium and did not show the asymmetric distribution in the myocardium. Cardiac-specific Notch1 deletion causes multiple structural defects and embryonic lethality. Notch1 or RBPJk deletion in MDKO did not rescue the structural defects in the MDKO but partially rescued the defects of cardiac progenitor cell differentiation, cardiomyocyte proliferation, and trabecular morphogenesis. Our study concludes that NFPs regulate progenitor cell differentiation, cardiomyocyte proliferation, and trabecular morphogenesis partially through Notch1 and play more roles than inhibiting Notch1 signaling during cardiac morphogenesis

Single-Cell Lineage Tracing Reveals that Oriented Cell Division Contributes to Trabecular Morphogenesis and Regional Specification

The cardiac trabeculae are sheet-like structures extending from the myocardium that function to increase surface area. A lack of trabeculation causes embryonic lethality due to compromised cardiac function. To understand the cellular and molecular mechanisms of trabecular formation, we genetically labeled individual cardiomyocytes prior to trabeculation via the brainbow multicolor system and traced and analyzed the labeled cells during trabeculation by whole-embryo clearing and imaging. The clones derived from labeled single cells displayed four different geometric patterns that are derived from different patterns of oriented cell division (OCD) and migration. Of the four types of clones, the inner, transmural, and mixed clones contributed to trabecular cardiomyocytes. Further studies showed that perpendicular OCD is an extrinsic asymmetric cell division that putatively contributes to trabecular regional specification. Furthermore, N-Cadherin deletion in labeled clones disrupted the clonal patterns. In summary, our data demonstrate that OCD contributes to trabecular morphogenesis and specification

Notch signaling regulates Hey2 expression in a spatiotemporal dependent manner during cardiac morphogenesis and trabecular specification

Abstract Hey2 gene mutations in both humans and mice have been associated with multiple cardiac defects. However, the currently reported localization of Hey2 in the ventricular compact zone cannot explain the wide variety of cardiac defects. Furthermore, it was reported that, in contrast to other organs, Notch doesn’t regulate Hey2 in the heart. To determine the expression pattern and the regulation of Hey2, we used novel methods including RNAscope and a Hey2 CreERT2 knockin line to precisely determine the spatiotemporal expression pattern and level of Hey2 during cardiac development. We found that Hey2 is expressed in the endocardial cells of the atrioventricular canal and the outflow tract, as well as at the base of trabeculae, in addition to the reported expression in the ventricular compact myocardium. By disrupting several signaling pathways that regulate trabeculation and/or compaction, we found that, in contrast to previous reports, Notch signaling and Nrg1/ErbB2 regulate Hey2 expression level in myocardium and/or endocardium, but not its expression pattern: weak expression in trabecular myocardium and strong expression in compact myocardium. Instead, we found that FGF signaling regulates the expression pattern of Hey2 in the early myocardium, and regulates the expression level of Hey2 in a Notch1 dependent manner

MULTIPLE CHOICES OF REACTOR CORE NUCLEAR DESIGN FOR ACP100’S APPLICATION IN DIFFERENT SCENARIOS

ACP100 NPP designed by CNNC (China National Nuclear Corporation) is a 125MWe, multi-purpose small modular reactor based on pressurized water reactor technology; it adopts the integrated reactor technology. Different application scenarios bring up different design requirements: some require high compactness, but others care more about a longer cycle length, and some may require a fully mature and conservative design; thus, multiple design choices need to be proposed. Also, the same and most important thing cared by all users is that, the design needs to be validated to satisfy the current nuclear safety standards, and lower cost would be always preferred. Core nuclear design is a key part of the whole NPP design. Basically, nuclear design target of ACP100 is to achieve a reasonable good balance during longer cycle length, larger discharge exposure for fuel assemblies, and maximally using the mature technologies, and of course, with sufficient reactivity control ability for safety assurance. Aiming at satisfying all these different needs maximally, a strategy of supplying multiple nuclear design choices is proposed for ACP100: choice 1. Boron-free plan, this is a compact design with no need for chemistry and volume system, no need for daily boron adjustment and relative waste storage; choice 2. Boron and rod co-controlled plan, this is similar with large commercial PWRs, with a lower power peak factor and suitable for broad location sites. Both choices load 57 units of the same type fuel assemblies CF3S (with height reduced from CF3 fuel assemblies) per cycle, and both adopt partial reload and shuffle fuel management strategy to achieve larger discharge exposure. Gd is loaded in the fuel rods in both choices to help control reactivity. Choice 1 loads much more control rod clusters than choice 2, and of course, reactivity adjustment and compensation during operation is totally different between them. Using suitable and reliable software to simulate the core, through large amount of optimization, both choices achieve a 24-month fuel cycle length; the average discharge exposure of fuel assemblies reach about 40000MWd/tU, which is competitive among SMRs, especially for boron-free ones; and sufficient reactivity control ability and safety margin is validated to fully meet the reactor safety requirements