Study on creep characteristics and component model of saline soil in hexi corridor.

Accurate mastery of the creep characteristics of unsaturated saline soil is extremely important for the long-term stability and safe operation of all types of buildings. In this paper, the research object focused on the saline soil of the Zhangye area, Hexi corridor. The indoor triaxial CU creep test was carried out by means of graded loading to study the creep characteristics of saline soil under different salt content and loading stress. The Merchant and Burgers models were used to predict the creep behavior of the saline soils, and the predicted results were compared with the experimental values. The results showed that the triaxial creep curve of saline soil developed in stage III. Namely, transient creep stage, deceleration creep stage and steady-state creep stage. The creep deformation increases with the increase of salt content and loading stress. The stress-strain isochronous curve has non-linear growth, and the cluster of curves develops from dense to sparse after increasing to long-term strength (100∼150 kPa). The parameters of the Merchant and Burgers model vary with salt content and loading stress, and the creep curve predicted by the Burgers model is closer to the test value.

Design and Synthesis of Bistetrazole-Based Energetic Salts Bearing the Nitrogen-Rich Fused Ring.

A series of bistetrazole-based energetic salts bearing a nitrogen-rich fused ring were designed and synthesized. Among them, compounds 4-10 showed good detonation properties and excellent thermostability. By treating nitrogen-rich fused ring 3 with concentrated hydrochloric acid, a new type of Dimroth rearrangement was observed that afforded compound 12 efficiently. This new transformation herein constitutes a valuable addition to the Dimroth rearrangement.

Stepwise Asymmetric Allylic Substitution-Isomerization Enabled Mimetic Synthesis of Axially Chiral B,N-Heterocycles.

Axially chiral molecules bearing multiple stereogenic axes are of great importance in the field of organic chemistry. However, the efficient construction of atropisomers featuring two different types of stereogenic axes has rarely been explored. Herein, we report the novel atroposelective synthesis of configurationally stable axially chiral B,N-heterocycles. By using stepwise asymmetric allylic substitution-isomerization (AASI) strategy, diaxially chiral B,N-heterocycles bearing B-C and C-N axes that are related to the moieties of axially chiral enamines and arylborons were also obtained. In this case, all four stereoisomers of diaxially chiral B,N-heterocycles were stereodivergently afforded in high enantioselectivities. Density functional theory (DFT) studies demonstrated that the NH⋅⋅⋅π interactions played a unique role in the promotion of stereospecific isomerization, thereby leading to the highly efficient central-to-axial chirality transfer.

Oxidative Stress Induced Osteocyte Apoptosis in Steroid-Induced Femoral Head Necrosis.

OBJECTIVE: To investigate the effect and mechanism of Glucocorticoids (GCs) induced oxidative stress and apoptosis on necrosis of the femoral head in patients and rats. METHODS: Eight patients with steroid-induced avascular necrosis of the femoral head (SINFH) and eight patients with developmental dysplasia of the hips (DDH) were enrolled in our study. In animal model, twenty male Sprague-Dawley rats were randomly divided into two groups (SINFH group and NS group). The SINFH model group received the methylprednisolone (MPS) injection, while control group was injected with normal saline (NS). MRI was used to confirm SINFH rat model was established successfully. Then, the rats were sacrificed 4 weeks later and femoral head samples were harvested. Histopathological staining was preformed to evaluate osteonecrosis. TUNEL staining was performed with 8-OHdG and DAPI immunofluorescence staining to evaluate oxidative injury and osteocyte apoptosis. Immunohistochemistry staining was used to detect Nox1, Nox2, and Nox4 protein expression. RESULTS: MRI showed signs of typical osteonecrosis of femoral head in SIHFH patients. Histopathological staining showed that the rate of empty lacunae in SINFH patients was significantly higher (56.88% ± 9.72% vs 19.92% ± 4.18%, T = -11.04, P < 0.001) than that in DDH patients. The immunofluorescence staining indicated that the TUNEL-positive cell and 8-OHdG-positve cell in SINFH patients were significantly higher (49.32% ± 12.95% vs 8.00% ± 2.11%, T = -7.04, P = 0.002, 54.6% ± 23.8% vs 9.75% ± 3.31%, T = -4.17, P = 0.003) compared to the DDH patients. The immunohistochemistry staining showed that the protein expression of NOX1, NOX2 and NOX4 in SINFH patients were significantly increased (64.50% ± 7.57% vs 37.58% ± 9.23%, T = -3.88, P = 0.018, 90.84% ± 2.93% vs 49.56% ± 16.47%, T = -5.46, P = 0.001, 85.46% ± 9.3% vs 40.69% ± 6.77%, T = -8.03, P = 0.001) compared to the DDH patients. In animal model, MRI showed signs of edema of femoral head in MPS group, which represents SINFH rat model was established successfully. Histological evaluation showed the rate of empty lacunae in MPS group was significantly higher (25.85% ± 4.68% vs 9.35% ± 1.99%, T = -7.96, P < 0.001) than that in NS group. The immunofluorescence staining indicated that the TUNEL-positive cell and 8-OHdG-positve cell (in MPS group were significantly increased (31.93% ± 1.01% vs 11.73% ± 1.16%, T = -32.26, P < 0.001, 47.59% ± 1.39% vs 22.07% ± 2.45%, T = -22.18, P < 0.001) compared to the NS group. The immunohistochemistry staining showed that the expression of NOX2 in MPS group was significantly increased (76.77% ± 8.34% vs 50.32% ± 10.84%, T = -4.74, P = 0.001) compare with NS group. CONCLUSION: Our findings indicated that GC-induced NOXs expression may be an important source of oxidative stress, which could lead to osteocyte apoptosis in the process of SINFH.

Symmetry-Induced Error Filtering in a Photonic Lieb Lattice.

Quantum computation promises intrinsically parallel information processing capacity by harnessing the superposition and entanglement of quantum states. However, it is still challenging to realize universal quantum computation due that the reliability and scalability are limited by unavoidable noises on qubits. Nontrivial topological properties like quantum Hall phases are found capable of offering protection, but require stringent conditions of topological band gaps and broken time-reversal symmetry. Here, we propose and experimentally demonstrate a symmetry-induced error filtering scheme, showing a more general role of geometry in protection mechanism and applications. We encode qubits in a superposition of two spatial modes on a photonic Lieb lattice. The geometric symmetry endows the system with topological properties featuring a flat band touching, leading to distinctive transmission behaviors of π-phase qubits and 0-phase qubits. The geometry exhibits a significant effect on filtering phase errors, which also enables it to monitor phase deviations in real time. The symmetry-induced error filtering can be a key element for encoding and protecting quantum states, suggesting an emerging field of symmetry-protected universal quantum computation and noisy intermediate-scale quantum technologies.

NADPH Oxidase Isoforms Are Involved in Glucocorticoid-Induced Preosteoblast Apoptosis.

Oxidative stress induced by long-term glucocorticoid (GC) use weakens the repair capacity of bone tissue. Nicotinamide adenine dinucleotide phosphate, reduced form (NADPH) oxidase (NOX) is a superoxide-generating enzyme that plays an important role in regulating bone metabolism. To clarify the role of nonphagocytic NOX isoforms in osteoblast reactive oxygen species (ROS) generation and apoptosis, dexamethasone was used to establish a high-dose GC environment in vitro. A dose-dependent increase in intracellular ROS generation was demonstrated, which was accompanied by increased osteoblastic MC3T3-E1 cell apoptosis. Addition of the ROS inhibitor NAC (N-acetyl-L-cysteine) or NOX inhibitor DPI (diphenyleneiodonium) reversed this effect, indicating that NOX-derived ROS can induce osteoblast apoptosis under high-dose dexamethasone stimulation. NOX1, NOX2, and NOX4 are NOX homologs recently identified in bone tissue. To clarify the NOX isoforms that play a role in osteoblast ROS generation, Nox1, Nox2, and Nox4 mRNA expression and NOX2 and NOX4 protein expression were analyzed. Nox1 and Nox4 mRNA expression was elevated in a dose-dependent manner after culture in 100 nM, 250 nM, 500 nM, or 1000 nM dexamethasone, and the increased expression of NOX1 mRNA was more significant compared with NOX4 mRNA. Small interfering RNAs (siRNAs) were used to confirm the role of NOX1 and NOX4 in ROS generation. To clarify the signaling pathway in ROS-induced osteoblast apoptosis, mitogen-activated protein kinase (MAPK) signaling molecules were analyzed. Phosphorylated ASK1 and p38 levels were significantly higher in the 1000 nM dexamethasone group, which NAC or DPI markedly attenuated. However, the total mRNA and protein levels of ASK1 and p38 between the dexamethasone group and control were not significantly different. This is related to ROS regulating the posttranslational modification of ASK1 and p38 in MC3T3-E1 cell apoptosis. Altogether, NOX1- and NOX4-derived ROS plays a pivotal role in high-dose dexamethasone-induced preosteoblast apoptosis by increasing phosphorylated ASK1 and p38 and may be an important mechanism in steroid-induced avascular necrosis of the femoral head (SANFH).

Analyses of very early hemopoietic regeneration after bone marrow transplantation: comparison of intravenous and intrabone marrow routes.

In bone marrow transplantation (BMT), bone marrow cells (BMCs) have traditionally been injected intravenously. However, remarkable advantages of BMT via the intra-bone-marrow (IBM) route (IBM-BMT) over the intravenous route (IV-BMT) have been recently documented by several laboratories. To clarify the mechanisms underlying these advantages, we analyzed the kinetics of hemopoietic regeneration after IBM-BMT or IV-BMT in normal strains of mice. At the site of the direct injection of BMCs, significantly higher numbers of donor-derived cells in total and of c-kit(+) cells were observed at 2 through 6 days after IBM-BMT. In parallel, significantly higher numbers of colony-forming units in spleen were obtained from the site of BMC injection. During this early period, higher accumulations of both hemopoietic cells and stromal cells were observed at the site of BMC injection by the IBM-BMT route. The production of chemotactic factors, which can promote the migration of a BM stromal cell line, was observed in BMCs obtained from irradiated mice as early as 4 hours after irradiation, and the production lasted for at least 4 days. In contrast, sera collected from the irradiated mice showed no chemotactic activity, indicating that donor BM stromal cells that entered systemic circulation cannot home effectively into recipient bone cavity. These results strongly suggest that the concomitant regeneration of microenvironmental and hemopoietic compartments in the marrow (direct interaction between them at the site of injection) contributes to the advantages of IBM-BMT over IV-BMT. Disclosure of potential conflicts of interest is found at the end of this article.