[en] Precision electron beam polarimetry is becoming increasingly important as parity violation experiments attempt to probe the frontiers of the standard model. In the few GeV regime, Moeller polarimetry is well suited to high-precision measurements, however is generally limited to use at relatively low beam currents (< 10 (micro)A). We present a novel technique that will enable precision Moeller polarimetry at very large currents, up to 100 (micro)A

[en] The Low Pressure-High Temperature (LPHT) System has been developed for sintering of nanophase cutter and anvil materials. Microstructured and nanostructured cutters were sintered and studied for rock drilling applications. The WC/Co anvils were sintered and used for development of High Pressure-High Temperature (HPHT) Systems. Binderless diamond and superhard nanophase cutter materials were manufactured with help of HPHT Systems. The diamond materials were studied for rock machining and drilling applications. Binderless Polycrystalline Diamonds (BPCD) have high thermal stability and can be used in geothermal drilling of hard rock formations. Nanophase Polycrystalline Diamonds (NPCD) are under study in precision machining of optical lenses. Triphasic Diamond/Carbide/Metal Composites (TDCC) will be commercialized in drilling and machining applications

[en] We present an application of the equivalence theorem and the multispinor representation of gauge fields to the standard model of electroweak interactions at very high energies. The equivalence theorem allows us to efficiently treat the longitudinal vector bosons while the multispinor formalism makes the transverse vector bosons easy to handle. We generalize the work of Berends and Giele to derive a recursion relation for a current consisting of a pair of longitudinal vector bosons plus any number of transverse vector bosons. It is shown that for longitudinal vector bosons plus any number of transverse vector bosons. Consideration of a U(N), rather than an SU(N), gauge theory enables us to incorporate the mixing in the SU(2)xU(1) electroweak theory and to derive certain sum rules for the currents for transverse gauge bosons. We also give explicit expressions for four-particle and five-particle scattering amplitudes involving a pair of longitudinal vector bosons. (orig.)

[en] Similarly to but quite different from the xenon poisoning effects resulting from fission-produced iodine during restart-up process of a fission reactor, we introduce a complete new concept of the tritium well depth and tritium well time in fusion energy research area. To show what the least required amount of tritium storage is used to start up a fusion reactor and how long a time the fusion reactor needs to be operated for achieving the tritium break-even during the initial start-up phase due to the finite tritium breeding time that is dependent on the tritium breeder, specific structure of breeding zone, layout of coolant flow pipes, tritium recovery scheme and extraction process, the tritium retention of reactor components, unrecoverable tritium fraction in breeder, leakage to the inertial gas container, and the natural decay etc, we describe this new phenomenon and answer this problem by setting up and by solving a set of equations, which express a dynamic subsystem model of the tritium inventory evolution in a fusion experimental breeder (FEB). Two different simulation models give almost the same results, It is found the tritium well depth is about 317-319g and tritium well time is approximately 240 full power days for reference case of the FEB designed detail configuration and it is also found that after one-year operation the tritium storage reaches 1.18kg that is more than the least required amount of tritium storage to start up three of FEB-like fusion reactors. (author)

[en] To investigate and compare the effect of decompression and fusion with internal fixation vs. simple decompression in the treatment of elderly patients with two-segment lumbar spinal stenosis (LSS) in perioperative and postoperative follow-up periods. Methods: Twenty-eight elderly patients with two-segment LSS admitted in Baoding First Hospital between Mar. 2017 and Jan. 2018 were retrospectively analyzed. Fifteen patients who underwent simple decompression were included in the simple decompression group, and 13 who underwent decompression and fusion with internal fixation were included in the decompression-fixation group. The general data and perioperative conditions including wound complications, operation time, blood loss, and VAS (legs) and JOA score were analyzed and compared between the two groups. Results: There was no significant difference in postoperative leg pain (VAS) between the two groups, and a statistically significant difference in JOA score was found between the two groups one month after the operation. The operation time, length of stay, and blood loss in the decompression-fixation group were significantly different from those in the simple decompression group and no significant difference in wound complications was observed between the two groups. Conclusion: There is no significant difference in leg pain relief in elderly patients with two-segment LSS when treated with decompression and fusion with internal fixation or simple decompression. Simple decompression is associated with less intraoperative injuries, better postoperative functional recovery, and reduced hospital stay. (author)

[en] With 2-years-old pomegranate (Punica granatum L.) cv. 'Tunisia' cuttings as materials, the growth properties, salt injury indexes, leaf membrane permeability, Chlorophyll (Chl) content, malondialdehyde (MDA) content, proline and soluble protein content, and activities of superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD) were investigated under different NaCl concentrations (0, 0.1, 0.2, 0.3, 0.4, 0.5, and 0.6%, w/w) treatments after 7, 21 and 35 days. The results showed that: the height and ground diameter of pomegranate were increased at low salinity (0.1%), and they were significantly inhibited at high salinity (= 0.5%). With increased NaCl concentrations, Chl a, Chl b, and Chl (a + b) contents were decreased and chlorophyll a/b were increased. Leaf membrane permeability was seriously enhanced and the amount of MDA was markedly increased at high salinity (= 0.5%). The proline and soluble protein were significantly accumulated and quickly responded to NaCl stress. The activities of SOD, CAT, and POD showed a trend of first rising and then decreasing, with the maximum appearing at 0.4% salinity. In addition, the adverse effects on these physiological indexes aggravated gradually over time. Our study suggested that pomegranate 'Tunisi' was a moderately salt tolerant cultivar (0.4% NaCl) with a promoting effect on the growth below 0.1% salinity. This cultivar presents a mechanism of alleviating the detrimental effects of salt stress through improving the proline content, soluble protein content and the activities of antioxidant enzymes. But the protections of antioxidant enzymes are in a limited range of salinity. (author)

[en] In the conventional approach to the 1/N_c expansion, electroweak interactions are switched off and large N_c QCD is treated in isolation. We study the self-consistency of taking the large N_c limit in the presence of electroweak interactions. If the electroweak coupling constants are held constant, the large N_c counting rules are violated by processes involving photon or weak boson lines. Anomaly cancellations, however, fix the ratio of electric charges of different fermions. This allows a self-consistent way to scale down the electronic charge e in the large N_c limit and, hence, restores the validity of the large N_c counting rules. copyright 1996 The American Physical Society

[en] Boron nitride-added eco-friendly free cutting steel has recently drawn more and more attention. But, the mechanisms explaining the role of BN inclusions improving the machinability of steels is not very clear. In this investigation, the material removal mechanism for cutting of BN inclusions in steels is explored, using a combination of theoretical analysis and a series of experiments. First, the actual shape of BN inclusions is observed and the amount and distribution of BN inclusions is quantitatively analyzed. Subsequently, the cutting performance of the steel is determined by cutting experimental tests. Moreover, the micro mechanical properties and the material removal mechanisms for cutting of BN inclusions are investigated by means of nano indentation. The results revealed that the BN inclusions are hexagonal and are uniformly distributed, their average content is 23.2 per unit area and their volume fraction is 0.51% in the steel with 74 ppm B and 180 ppm N. It is shown that BN inclusions can improve the cutting performance of steel significantly, and a model describing the material removal mechanism for cutting of BN inclusions is proposed. BN inclusions act as stress concentration source, lubrication and wrap page of hard particles. (Author)

[en] Purpose: To develop a delivery-efficient proton spot-scanning arc therapy technique with robust plan quality. Methods: We developed a Scanning Proton Arc(SPArc) optimization algorithm integrated with (1)Control point re-sampling by splitting control point into adjacent sub-control points; (2)Energy layer re-distribution by assigning the original energy layers to the new sub-control points; (3)Energy layer filtration by deleting low MU weighting energy layers; (4)Energy layer re-sampling by sampling additional layers to ensure the optimal solution. A bilateral head and neck oropharynx case and a non-mobile lung target case were tested. Plan quality and total estimated delivery time were compared to original robust optimized multi-field step-and-shoot arc plan without SPArc optimization (Arcmulti-field) and standard robust optimized Intensity Modulated Proton Therapy(IMPT) plans. Dose-Volume-Histograms (DVH) of target and Organ-at-Risks (OARs) were analyzed along with all worst case scenarios. Total delivery time was calculated based on the assumption of a 360 degree gantry room with 1 RPM rotation speed, 2ms spot switching time, beam current 1nA, minimum spot weighting 0.01 MU, energy-layer-switching-time (ELST) from 0.5 to 4s. Results: Compared to IMPT, SPArc delivered less integral dose(−14% lung and −8% oropharynx). For lung case, SPArc reduced 60% of skin max dose, 35% of rib max dose and 15% of lung mean dose. Conformity Index is improved from 7.6(IMPT) to 4.0(SPArc). Compared to Arcmulti-field, SPArc reduced number of energy layers by 61%(276 layers in lung) and 80%(1008 layers in oropharynx) while kept the same robust plan quality. With ELST from 0.5s to 4s, it reduced 55%–60% of Arcmulti-field delivery time for the lung case and 56%–67% for the oropharynx case. Conclusion: SPArc is the first robust and delivery-efficient proton spot-scanning arc therapy technique which could be implemented in routine clinic. For modern proton machine with ELST close to 0.5s, SPArc would be a popular treatment option for both single and multi-room center.

[en] Purpose: To develop an efficient and accurate independent dose calculation algorithm with a simplified analytical source model for the quality assurance and safe delivery of Flattening Filter Free (FFF)-IMRT on an Elekta Versa HD. Methods: The source model consisted of a point source and a 2D bivariate Gaussian source, respectively modeling the primary photons and the combined effect of head scatter, monitor chamber backscatter and collimator exchange effect. The in-air fluence was firstly calculated by back-projecting the edges of beam defining devices onto the source plane and integrating the visible source distribution. The effect of the rounded MLC leaf end, tongue-and-groove and interleaf transmission was taken into account in the back-projection. The in-air fluence was then modified with a fourth degree polynomial modeling the cone-shaped dose distribution of FFF beams. Planar dose distribution was obtained by convolving the in-air fluence with a dose deposition kernel (DDK) consisting of the sum of three 2D Gaussian functions. The parameters of the source model and the DDK were commissioned using measured in-air output factors (Sc) and cross beam profiles, respectively. A novel method was used to eliminate the volume averaging effect of ion chambers in determining the DDK. Planar dose distributions of five head-and-neck FFF-IMRT plans were calculated and compared against measurements performed with a 2D diode array (MapCHECK™) to validate the accuracy of the algorithm. Results: The proposed source model predicted Sc for both 6MV and 10MV with an accuracy better than 0.1%. With a stringent gamma criterion (2%/2mm/local difference), the passing rate of the FFF-IMRT dose calculation was 97.2±2.6%. Conclusion: The removal of the flattening filter represents a simplification of the head structure which allows the use of a simpler source model for very accurate dose calculation. The proposed algorithm offers an effective way to ensure the safe delivery of FFF-IMRT.