Influence of initial ovality on creep life of P92 pipe bends subjected to in-plane bending

Initial ovality is an inevitable problem in the process of pipe bends manufacturing which results in the stress redistribution of the pipe bends working at high temperature. In order to study the influence of ovality on creep life of pipe bends, full-size creep experiment of P92 pipe bend subjected to in-plane bending has been conducted. The creep strains and outside diameters of dangerous positions have been measured. The microstructures of three different positions of the pipe bend were compared through SEM and the results showed the number and size of the carbide precipitation were the largest at the flank of the pipe bend, which indicated that the creep damage developed fastest at the flank. The modified Kachanov–Robatnov constitutive equations were used to stimulate the creep of P92 pipe bends with FEA software. The representative stress, damage and multiaxiality distributions of the pipe bends have been discussed. The FEA results were consistent with the experimental results and the influence of initial ovality on creep life of P92 pipe bends were analyzed. The results showed that creep life of pipe bends reduced by the increase of ovality and their relationship coincided with the parabolic law.     

Metal binding novel flaxseed peptides (linusorbs)

Linusorbs (LOs; a.k.a. cyclolinopeptides) are naturally occurring orbitides derived from flaxseed. These compounds consist of 8–10 amino acid residues, which are linked via an N ‐ to C‐terminal peptide bond with molecular masses of approximately 1 kDa. The LO circular structure makes them candidates for metal binding studies. Flaxseed extracts are known to suppress Pb and Cd toxicity. Hence, four metal salts surveyed include Zn(CH₃COO)₂, ZnSO₄, Pb(CH₃COO)₂ and Cd(NO₃)₂ with pure LOs 1–5 . Proton NMR spectra indicated interaction of LOs with metal salts in solution and were used to determine impacts of methionine oxidation on interactions with metal ions. The methyl group of methionine S,S ‐ dioxide of related LOs did not show the same shift in the presence of Zn(CH₃COO)₂ and Pb(CH₃COO)₂ observed in their methionine S ‐ oxide analogues. Metal complexes were observed forming at 10^?2 m to 10^?4 m but not at lower concentrations (10^?5 m to 10^?8 m ). Mass spectrometry data confirmed that metal binding strength varied by metal in the order Zn(CH₃COO)₂<Pb(CH₃COO)₂<ZnSO₄<Cd(NO₃)₂.     

Miscible-Solvent-Assisted Two-Phase Synthesis of Monolayer-Ligand-Protected Metal Nanoclusters with Various Sizes

Effective yet versatile synthetic strategies for size-tunable metal nanoclusters (NCs) are scarce. This has hampered the development of this unique class of nanomaterials. Here, a general protocol is reported for the synthesis of high-quality metal NCs protected by a variety of organic ligands (e.g., selenolate, thiolate, and phosphine) based on a miscible-solvent-assisted phase transfer between water and organic solution. This method is demonstrated to be facile, rapid (≤3 h), scalable (gram-scale), and versatile. The size of the selenolated and thiolated Au NCs can be tuned from Au₁₀ to Au₆₁ by simply varying the miscible solvent in proportions and types. The advantages of this method, such as quick phase separation and no need for purification treatment, enable real-time monitoring of metal NC growth within the NaBH₄ reduction system. The results show that the size of Au NCs gradually increases with increasing valence electron count by a stepwise 2x e^- hopping mechanism (x = 0–5), i.e., 0 e^- → 2 e^- → 4 e^- → 8 e^- → 18 e^- → 22 e^- → 32 e^-.     

Optimization of energy-group structure for LWR high-fidelity neutronics calculation based on the contributon theory

ABSTRACT

Deterministic high-fidelity neutronics calculation is to solve the neutron transport equation using the multi-group (MG) nuclear data libraries. The energy-group structure (ES) in MG nuclear data libraries has a significant impact on the precision and efficiency of neutronics calculation. Therefore, to meet the requirement of high precision and efficiency for high-fidelity neutronics calculation, the contributon theory is adopted to select the optimal ESs for the high-fidelity neutronics code NECP-X which is developed by Nuclear Engineering Computational Physics (NECP) lab. at Xi’an Jiaotong University (XJTU). By combining the contributon theory with the exhaustive searching method, the optimal ESs can be selected effectively. Two optimal ESs named NECP-69 and NECP-47 are obtained and the nuclear data processing code NECP-Atlas developed by NECP lab. is utilized to generate the corresponding MG nuclear data libraries for NECP-X. The neutronics parameters of the MOX pin cell problems and the VERA benchmarks are evaluated. The numerical results show that more precise neutronics parameters are obtained based on the optimal ESs compared with those based on the conventional WIMS-69 and HELIOS-47 for NECP-X.     

Healable,Recyclable, and Mechanically Tough Polyurethane Elastomers with Exceptional Damage Tolerance

There is a huge requirement of elastomers for use in tires, seals, and shock absorbers every year worldwide. In view of a sustainable society, the next generation of elastomers is expected to combine outstanding healing, recycling, and damage-tolerant capacities with high strength, elasticity, and toughness. However, it remains challenging to fabricate such elastomers because the mechanisms for the properties mentioned above are mutually exclusive. Herein, the fabrication of healable, recyclable, and mechanically tough polyurethane (PU) elastomers with outstanding damage tolerance by coordination of multiblock polymers of poly(dimethylsiloxane) (PDMS)/polycaprolactone (PCL) containing hydrogen and coordination bonding motifs with Zn²⁺ ions is reported. The organization of bipyridine groups coordinated with Zn²⁺ ions, carbamate groups cross-linked with hydrogen bonds, and crystallized PCL segments generates phase-separated dynamic hierarchical domains. Serving as rigid nanofillers capable of deformation and disintegration under an external force, the dynamic hierarchical domains can strengthen the elastomers and significantly enhance their toughness and fracture energy. As a result, the elastomers exhibit a tensile strength of ≈52.4 MPa, a toughness of ≈363.8 MJ m⁻³, and an exceptional fracture energy of ≈192.9 kJ m⁻². Furthermore, the elastomers can be conveniently healed and recycled to regain their original mechanical properties and integrity under heating.     

Metal-polyphenol-network coated CaCO3 as pH-responsive nanocarriers to enable effective intratumoral penetration and reversal of multidrug resistance for augmented cancer treatments

Construction of multifunctional stimuli-responsive nanotherapeutics enabling improved intratumoral penetration of therapeutics and reversal of multiple-drug resistance (MDR) is potent to achieve effective cancer treatment. Herein, we report a general method to synthesize pH-dissociable calcium carbonate (CaCO₃) hollow nanoparticles with amorphous CaCO₃ as the template, gallic acid (GA) as the organic ligand, and ferrous ions as the metallic center via a one-pot coordination reaction. The obtained GA–Fe@CaCO₃ exhibits high loading efficiencies to both oxidized cisplatin prodrug and doxorubicin, yielding drug loaded GA–Fe@CaCO₃ nanotherapeutics featured in pH-responsive size shrinkage, drug release, and Fenton catalytic activity. Compared to nonresponsive GA–Fe@silica nanoparticles prepared with silica nanoparticles as the template, such GA–Fe@CaCO₃ confers significantly improved intratumoral penetration capacity. Moreover, both types of drug-loaded GA–Fe@CaCO₃ nanotherapeutics exhibit synergistic therapeutic efficacies to corresponding MDR cancer cells because of the GA–Fe mediated intracellular oxidative stress amplification that could reduce the efflux of engulfed drugs by impairing the mitochondrial-mediated production of adenosine triphosphate (ATP). As a result, it is found that the doxorubicin loaded GA–Fe@CaCO₃ exhibits superior therapeutic effect towards doxorubicin-resistant 4T1 breast tumors via combined chemodynamic and chemo-therapies. This work highlights the preparation of pH-dissociable CaCO₃-based nanotherapeutics to enable effective tumor penetration for enhanced treatment of drug-resistant tumors.

     

多硝基3,3,7,7-四（三氟甲基）-2,4,6,8-四氮杂双环[3.3.0]辛烷的合成与性能

为了探索三氟甲基对含能材料性能的影响,以偕二氨基六氟丙烷和乙二醛为原料构建了氮杂稠环类含能材料的硝化前体——3,3,7,7-四(三氟甲基)-2,4,6,8-四氮杂双环[3.3.0]辛烷,通过改进的合成路线,用发烟硝酸多步硝化分别得到2,6-二硝基-3,3,7,7-四(三氟甲基)-2,4,6,8-四氮杂双环[3.3.0]辛烷(4)、2,4,6-三硝基-3,3,7,7-四(三氟甲基)-2,4,6,8-四氮杂双环[3.3.0]辛烷(5)和2,4,6,8-四硝基6-3,3,7,7-四(三氟甲基)-2,4,6,8-四氮杂双环[3.3.0]辛烷(6)。利用核磁共振氢谱、碳谱和氮谱表征了产物结构;采用排惰性气体法测试了三种硝化产物的密度,其中6的密度最大,高达2.08 g·cm~(-3);分别用落锤升降法和BAM法测得三种产物的撞击感度均大于30 J、摩擦感度均大于360 N;热重-微商热重(TG-DTG)分析发现三种产物的质量损失均大于90%,其热稳定性随硝基的增加而下降;利用Gaussian 09计算包,通过Monte-Carlo统计学方法以及Kamlet-Jacbos方程和VLW爆轰产物状态方程等理论模型预估了产物的爆速、爆压,其中化合物6的爆速为1 1937 m·s~(-1),爆压为74.3 GPa。与四硝基甘脲(TNGU)的性能及感度对比发现,在含能材料的分子结构中引入具有更高密度和更大电负性的三氟甲基,可在维持较高密度和良好爆轰性能的同时降低感度。     

致密油藏注天然气提高采收率研究现状

随着我国石油需求量不断增加,致密油藏的开发也愈发重要。如何高效开发致密油藏是一项重点难点,其中致密油藏注天然气提高采收率是一个极具潜力的研究方向。因此,本文着重介绍以天然气作为能量补充介质在国内外的研究现状和应用现状,并且从两相特征等方面总结了理论研究中的一些机理,对致密油藏注天然气提高采收率的发展前景进行了一定的展望。     

高效液相色谱法测定纺织品中喹啉的质量浓度

建立了测定纺织品中喹啉质量浓度的高效液相色谱检测方法,用高效液相色谱仪对样品中的喹啉及其他组分进行分离,用二极管阵列检测器进行紫外光谱分析,用峰面积外标法进行定量。喹啉的检出限为10 mg/kg,回收率在80%~120%,精密度小于2%。结果表明,该方法线性良好,测试简单,回收率、精密度高,满足测试要求。     

Interfacial Crystallization of Diacylglycerols Rich in Medium‐ and Long‐Chain Fatty Acids in Water‐in‐Oil Emulsions

The effects of diacylglycerols rich in medium‐ and long‐chain fatty acids (MLCD) on the crystallization of hydrogenated palm oil (HPO) and formation of 10% water‐in‐oil (W/O) emulsion are studied, and compared with the common surfactants monostearoylglycerol (MSG) and polyglycerol polyricinoleate (PGPR). Polarized light microscopy reveals that emulsions made with MLCD form crystals around dispersed water droplets and promotes HPO crystallization at the oil‐water interface. Similar behavior is also observed in MSG‐stabilized emulsions, but is absent from emulsions made with PGPR. The large deformation yield value of the test W/O emulsion is increased four‐fold versus those stabilized via PGPR due to interfacial crystallization of HPO. However, there are no large differences in droplet size, solid fat content (SFC), thermal behavior or polymorphism to account for these substantial changes, implying that the spatial distribution of the HPO crystals within the crystal network is the driving factor responsible for the observed textural differences. MLCD‐covered water droplets act as active fillers and interact with surrounding fat crystals to enhance the rigidity of emulsion. This study provides new insights regarding the use of MLCD in W/O emulsions as template for interfacial crystallization and the possibility of tailoring their large deformation behavior. Practical Applications: MLCD is applied in preparing W/O emulsion. It is found that MLCD forms unique interfacial Pickering crystals around water droplets, which promote the surface‐inactive HPO nucleation at the oil‐water interface. Thus MLCD‐covered water droplets act as active fillers and interact with surrounding fat crystals, which can greatly enhance the rigidity of emulsion. This observation would provide a theoretical reference and practical basis for the application of the MLCD with appreciable nutritional properties in lipid‐rich products such as whipped cream, shortenings margarine, butter and ice cream, so as to substitute hydrogenated oil. MLCD‐stabilized emulsions can also be explored for the development of novel confectionery products, lipsticks, or controlled release matrices.