Abstract
Developing affordable and light high-temperature materials alternative to Ni-base superalloys has significantly increased the efforts in designing advanced ferritic superalloys. However, ...currently developed ferritic superalloys still exhibit low high-temperature strengths, which limits their usage. Here we use a CALPHAD-based high-throughput computational method to design light, strong, and low-cost high-entropy alloys for elevated-temperature applications. Through the high-throughput screening, precipitation-strengthened lightweight high-entropy alloys are discovered from thousands of initial compositions, which exhibit enhanced strengths compared to other counterparts at room and elevated temperatures. The experimental and theoretical understanding of both successful and failed cases in their strengthening mechanisms and order-disorder transitions further improves the accuracy of the thermodynamic database of the discovered alloy system. This study shows that integrating high-throughput screening, multiscale modeling, and experimental validation proves to be efficient and useful in accelerating the discovery of advanced precipitation-strengthened structural materials tuned by the high-entropy alloy concept.
Magnetic materials with excellent performances are desired for functional applications. Based on the high-entropy effect, a system of CoFeMnNiX (X = Al, Cr, Ga, and Sn) magnetic alloys are designed ...and investigated. The dramatic change in phase structures from face-centered-cubic (FCC) to ordered body-centered-cubic (BCC) phases, caused by adding Al, Ga, and Sn in CoFeMnNiX alloys, originates from the potent short-range chemical order in the liquid state predicted by ab initio molecular dynamics (AIMD) simulations. This phase transition leads to the significant enhancement of the saturation magnetization (Ms), e.g., the CoFeMnNiAl alloy has Ms of 147.86 Am2/kg. First-principles density functional theory (DFT) calculations on the electronic and magnetic structures reveal that the anti-ferromagnetism of Mn atoms in CoFeMnNi is suppressed especially in the CoFeMnNiAl HEA because Al changes the Fermi level and itinerant electron-spin coupling that lead to ferromagnetism.
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This article provides a short review on computational modeling on the formation, thermodynamics, and elasticity of single-phase high-entropy alloys (HEAs). Hundreds of predicted single-phase HEAs ...were re-examined using various empirical thermo-physical parameters. Potential BCC HEAs (CrMoNbTaTiVW, CrMoNbReTaTiVW, and CrFeMoNbReRuTaVW) were suggested based on CALPHAD modeling. The calculated vibrational entropies of mixing are positive for FCC CoCrFeNi, negative for BCC MoNbTaW, and near-zero for HCP CoOsReRu. The total entropies of mixing were observed to trend in descending order: CoCrFeNi > CoOsReRu > MoNbTaW. Calculated lattice parameters agree extremely well with averaged values estimated from the rule of mixtures (ROM) if the same crystal structure is used for the elements and the alloy. The deviation in the calculated elastic properties from ROM for select alloys is small but is susceptible to the choice used for the structures of pure components.
An effective computational scheme to calculate the complete set of independent elastic constants as well as other structural parameters including bulk modulus, shear modulus, Young's modulus, and ...Poisson's ratio for crystals is reported. The scheme is based on the stress–strain analysis approach with the appropriate selection of strain governed by symmetry consideration. The first principles Vienna ab initio simulation package (VASP) is used in stress calculations. Comprehensive tests were performed for α‐SiO2 and spinel MgAl2O4 with different exchange‐correlation potentials, and different sets of computational parameters to investigate the relative accuracies of the calculations. A wide range of oxides, nitrides, and carbonate crystals with different crystal symmetries were chosen to test the scheme under both LDA and GGA approximations at zero temperature and pressure. Some of these calculations for large complex crystals are believed to be attempted for the first time. The calculated elastic constants show quite good agreement with the existing experimental data for almost all the examined systems with the exception of the relatively soft material such as α‐SiO2 and the C14 parameter of some trigonal crystals expressed in the hexagonal form such as in α‐Al2O3. Other structural properties derived from the elastic constants also show good agreements with the measured values.
Objective
Proximal humeral fracture combined with contralateral midshaft clavicle fracture is an extremely rare injury in children. Few studies focus on the injury mechanism and treatment scheme. The ...aim of this study is to propose the possible mechanism of this injury and present the treatment results.
Methods
This retrospective study included children diagnosed with proximal humeral fractures combined with contralateral midshaft clavicle fractures from August 2016 to March 2019 in the corresponding author's institution. The patients received elastic stable intramedullary nails and external fixation as treatment. The radiological and clinical outcomes of treatments were evaluated using the imaging and the Constant–Murley score (CMS) in follow up.
Results
Twelve patients (eight males and four females) with an average age of 7.83 years old (age 5–12) were included in this research. All the patients had suffered a side impact in a road traffic accident or outdoor environment. Hypothesis about the mechanism was the proximal humerus was directly impacted at first and caused the surgical neck fracture, then the contralateral shoulder hits the solid object and the contralateral midshaft clavicle was fractured. During the average 45.2 months (range 36–57) follow‐up, all the patient's fractures achieved clinical and radiological union before 14 weeks without complications. Every patient had a satisfactory score (range from 92 to 100) on the CMS criteria for both shoulders.
Conclusion
The hypothesis about the mechanism of this combined injury in this study sounds reasonable. It highlights the need for safety‐related education about using a safety seat or wearing a seat belt to parents and caregivers, so as to avoid such injury even if the treatment with external fixation (EF) and proximal humeral and elastic stable intramedullary nailing (ESIN) showed good results.
Hypothesis about the mechanism of proximal humeral fractures combined with contralateral midshaft clavicle fractures: The proximal humerus is directly impacted by a strong lateral force, which leaves the surgical neck vulnerable to damage. The impact force causes the body to rush towards the opposite side until the contralateral shoulder hits the solid object. Due to the lack of muscle and ligament protection, the contralateral midshaft clavicle is prone to fracture when both ends are subjected to strong compression.
Objective
Combined fractures of the lateral condyle of the humerus and the ipsilateral ulnar olecranon are rarely seen in children. Therefore, the mechanism and suitable treatments remain debatable. ...This study describes the possible mechanism of combined humeral lateral condyle and ipsilateral ulnar olecranon fractures and presents the treatment results.
Methods
Children diagnosed with combined fractures of the humeral lateral condyle and ipsilateralulnar olecranon from July 2010 to July 2020 were retrospectively analyzed. Humeral lateral condyle fractures were treated with open reduction and internal fixation with bioabsorbable pins. Ulnar olecranon fractures were treated with closed reduction and percutaneous pinning with K‐wires for Mayo type IA fractures and with tension‐band wiring or a locking plate for Mayo type IIA fractures. The postoperative function and appearance of the elbow were evaluated using the Flynn criteria and Mayo Elbow Performance Score (MEPS) at follow‐up.
Results
The cohort comprised 19 patients aged from 4 to 11 years. Bony compression and avulsion by attached muscles and ligaments may be the leading factors causing the combined injuries, as the children fell with an outstretched and supinated elbow. The average follow‐up time was 33 months. High MEPS of >90 indicated that good to excellent results were obtained without complications.
Conclusions
This study proposed a reasonable hypothesis for the mechanism of combined humeral lateral condyle and ipsilateral ulnar olecranon fractures in children. Satisfactory outcomes were achieved with bioabsorbable pins for lateral condyle fractures and closed reduction and percutaneous pinning with K‐wires, tension‐band wiring, or locking plate for olecranon fractures.
Hypothetical diagram of the mechanism of combined fractures of lateral condyle of the humerus and ipsilateral olecranon. This fracture occurs as the children fall on an outstretched and supinated elbow. An upward cubits varus stress is transmitted axially through the elbow joint to the lateral condyle. The olecranon is compressed and levered by the distal humerus during the process, resulting in fractures. Alternatively, the olecranon may be fractured as the forearm externally rotates against the distal humerus and pulls off the lateral condyle through tensed lateral collateral ligament complex. Contracted triceps muscle and arm extensors may also be important contributors.
•Addition of 10 elements lowers the enthalpy of formation noticeably, namely, Mg, Al, Sc, Ti, Y, Hf, Zr, Ga, La, and Zn.•Compromise between enthalpy and solubility suggests these alloying elements: ...V, Fe, Cr, Nb, Ta, and Mn.•Electronegativity correlates qualitatively well with the enthalpy of formation.
We report here a screening study using first-principles method in an attempt to identify ternary elements that can extend the CuPd B2 phase field at reduced Pd contents and thus lower cost. A total of 37 alloying elements are included for unbiased screening. The results show that addition of Mg, Al, Sc, Ti, Y, Hf, Zr, Ga, La, and Zn lowers the enthalpy of formation of the B2 phase noticeably. The atomic size, electronic density of states, charge transfer, and electronegativity are analyzed to interpret the results. Compromise between enthalpy and solubility suggests additional potential alloying elements: V, Fe, Cr, Nb, Ta, and Mn. To assess the effects of alloying on mechanical properties, we calculated the equation of states and elastic constants of 10 example alloys at 6.25at% solute contents.
Objective
To observe the efficacy of herbal cake-partitioned moxibustion for lumbar disc herniation (LDH) due to kidney deficiency and blood stasis and observe the influence of this method on lumbar ...functions and inflammatory factors in patients with this condition.
Methods
A total of 120 LDH patients who met the inclusion criteria were randomly divided into three groups, including a herbal cake-partitioned moxibustion group, a flour cake-partitioned moxibustion group, and a Western medication group, with 40 patients in each group. The patients in the Western medication group were treated with diflunisal tablets, 0.5 g per dose, 2 doses a day. Those in the herbal cake-partitioned moxibustion group were treated with additional herbal cake-partitioned moxibustion group at Back-Shu Points and Jiaji (EX-B2) Points once a day. Those in the flour cake-partitioned moxibustion group were treated with the same methods as in the herbal cake-partitioned moxibustion group, except that the herbal cake was replaced by a flour cake. All the patients were treated for 10 d. After treatment, the scores of the visual analog scale (VAS) and Japanese Orthopaedic Association (JOA) and the changes of the interleukin (IL)-6, tumor necrosis factor (TNF)-α, and substance P (SP) levels were observed, and the efficacy was evaluated.
Results
After treatment, the VAS score and the levels of IL-6, TNF-α, and SP were lower than those before treatment, and the JOA score was higher than that before treatment in the three groups, indicating intra-group statistical significance (
P
<0.05). The VAS score and the levels of IL-6, TNF-α, and SP of the herbal cake-partitioned moxibustion group were lower than those of the flour cake-partitioned moxibustion group and the Western medication group, while the JOA score of the herbal cake-partitioned moxibustion group was higher than that of the other two groups, indicating inter-group statistical significance (
P
<0.05). The total effective rate of the herbal cake-partitioned moxibustion group was 92.5%, higher than that of the flour cake-partitioned moxibustion group (80.0%) and the Western medication group (72.5%), indicating inter-group statistical significance (
P
<0.05).
Conclusion
On the basis of Western oral medication, additional herbal cake-partitioned moxibustion can alleviate the pain and improve the lumbar functions in patients with LDH due to kidney deficiency and blood stasis. The efficacy of the integrated method is better than that of either flour cake-partitioned moxibustion or Western medication alone, which may be related to the reduction of serum inflammatory factors.
The electronic structure, bonding, and optical properties of six polymorphs of SiC: 3C, 2H, 4H, 6H, 15R, and 21R were studied by the density functional-based first-principles OLCAO method. The ...results were compared with other existing calculations as well as experimental data. It is shown that the different stacking sequences of the Si–C bi-layers in these polymorphs result in minute but recognizable differences in the partial density of states, Mulliken effective charges, and bond order values, indicating the importance of the intermediate range ordering in these crystals. The optical properties calculation for these polymorphs also shows some marked differences among them and can be explained, at least partially, by the LDA-based electronic band structures. Also presented is the calculated X-ray absorption near edge spectroscopy (XANES) of the Si-K, Si-L
3 and N-K edges in 3C-SiC.
New Delhi metallo-beta-lactamase (NDM)-producing Klebsiella pneumoniae is increasingly reported worldwide. Clinicians face significant challenges in the treatment of this multidrug-resistant ...bacterium. The combination of ceftazidime/avibactam (CAZ/AVI) and aztreonam (ATM) is currently probably the most effective strategy for the treatment of such infection. We described a patient diagnosed with NK/T cell lymphoma who underwent autologous hematopoietic stem cell transplantation (ASCT) in the hematology department. The patient developed severe infection after ASCT. Blood and stool cultures showed carbapenem-resistant K. pneumoniae. Blood sample was detected as NDM-producing K. pneumoniae. We successfully treated this infection with CAZ/AVI and ATM.
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