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1.
Head Neck Pathol ; 18(1): 56, 2024 Jun 25.
Article in English | MEDLINE | ID: mdl-38916683

ABSTRACT

BACKGROUND: Angiosarcoma is a sarcoma that occurs in a range of tissue types, and only rarely in the salivary glands, showing a predilection for the parotid glands of older patients. Preoperative diagnosis may be challenging, especially on cytology, with significant morphological overlap with high-grade primary salivary gland carcinomas. The molecular alterations of this rare salivary gland neoplasm are also not well-characterized. METHODS AND RESULTS: We present a case of right submandibular gland swelling in a 73-year-old male. On fine needle aspiration, including immunohistochemical stains on cell block, the tumor was initially diagnosed as poorly differentiated carcinoma. Resection of the submandibular gland revealed epithelioid angiosarcoma. We performed molecular work-up of the tumor, utilizing targeted next-generation sequencing, DNA methylation profiling and fluorescence in-situ hybridization. Histopathologic assessment revealed an infiltrative tumor comprising solid sheets of epithelioid cells. The tumor cells formed haphazardly anastomosing vascular channels with intracytoplasmic lumina containing red blood cells. On immunohistochemistry, the tumor cells were positive for CD31, CD34 and ERG. Approximately 40% of the tumor cells showed nuclear expression of GATA3. A pathogenic TP53 R267W mutation was detected on next-generation sequencing. DNA methylation analysis did not cluster the tumor with any known sarcoma type. Copy number analysis showed possible MYC amplification and CDKN2A losses, although only the latter was confirmed on fluorescence in-situ hybridization. CONCLUSION: Epithelioid angiosarcoma is an important differential diagnosis to high-grade salivary gland carcinoma. In particular, GATA3 expression may be encountered in both angiosarcoma and high-grade salivary gland carcinomas and cause diagnostic confusion. Identification of TP53 mutations and CDKN2A losses suggest shared oncogenic pathways with soft tissue angiosarcomas, and should be further investigated.


Subject(s)
Hemangiosarcoma , Submandibular Gland Neoplasms , Humans , Male , Aged , Hemangiosarcoma/genetics , Hemangiosarcoma/pathology , Hemangiosarcoma/diagnosis , Submandibular Gland Neoplasms/pathology , Submandibular Gland Neoplasms/genetics , Submandibular Gland Neoplasms/diagnosis , Biomarkers, Tumor/analysis , Biomarkers, Tumor/genetics , Cytology
2.
Small Methods ; : e2301603, 2024 Mar 08.
Article in English | MEDLINE | ID: mdl-38459640

ABSTRACT

There is a growing interest in developing paramagnetic nanoparticles as responsive magnetic resonance imaging (MRI) contrast agents, which feature switchable T1 image contrast of water protons upon biochemical cues for better discerning diseases. However, performing an MRI is pragmatically limited by its cost and availability. Hence, a facile, routine method for measuring the T1 contrast is highly desired in early-stage development. This work presents a single-point inversion recovery (IR) nuclear magnetic resonance (NMR) method that can rapidly evaluate T1 contrast change by employing a single, optimized IR pulse sequence that minimizes water signal for "off-state" nanoparticles and allows for sensitively measuring the signal change with "switch-on" T1 contrast. Using peptide-induced liposomal gadopentetic acid (Gd3+ -DTPA) release and redox-sensitive manganese oxide (MnO2 ) nanoparticles as a demonstration of generality, this method successfully evaluates the T1 shortening of water protons caused by liposomal Gd3+ -DTPA release and Mn2+ formation from MnO2 reduction. Furthermore, the NMR measurement is highly correlated to T1 -weighted MRI scans, suggesting its feasibility to predict the MRI results at the same field strength. This NMR method can be a low-cost, time-saving alternative for pre-MRI evaluation for a diversity of responsive T1 contrast systems.

3.
Curr Med Chem ; 2024 Feb 12.
Article in English | MEDLINE | ID: mdl-38347784

ABSTRACT

Antioxidant research has recently become a popular topic. Medicinal plants are important sources of novel active compounds. Diarylheptanoids, a typical family of secondary plant metabolites, are of great interest owing to their extensive spectrum of biological activities. They possess a unique 1,7-diphenylmethane structural skeleton. Thus, this review summarizes the natural linear or macrocyclic diarylheptanoids with antioxidant activity in the last two decades. In addition, the relationships between the structural characteristics of natural diarylheptanoids and their antioxidant capacity were also discussed. All the available data highlight the potential of natural diarylheptanoids as novel antioxidants.

4.
Front Bioeng Biotechnol ; 12: 1350024, 2024.
Article in English | MEDLINE | ID: mdl-38282893

ABSTRACT

Objective: A model of chronic infectious mandibular defect (IMD) caused by mixed infection with Staphylococcus aureus and Pseudomonas aeruginosa was established to explore the occurrence and development of IMD and identify key genes by transcriptome sequencing and bioinformatics analysis. Methods: S. aureus and P. aeruginosa were diluted to 3 × 108 CFU/mL, and 6 × 3 × 3 mm defects lateral to the Mandibular Symphysis were induced in 28 New Zealand rabbits. Sodium Morrhuate (0.5%) and 50 µL bacterial solution were injected in turn. The modeling was completed after the bone wax closed; the effects were evaluated through postoperative observations, imaging and histological analyses. Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway, and protein‒protein interaction (PPI) network analyses were performed to investigate the function of the differentially expressed genes (DEGs). Results: All rabbits showed characteristics of infection. The bacterial cultures were positive, and polymerase chain reaction (PCR) was used to identify S. aureus and P. aeruginosa. Cone beam CT and histological analyses showed inflammatory cell infiltration, pus formation in the medullary cavity, increased osteoclast activity in the defect area, and blurring at the edge of the bone defect. Bioinformatics analysis showed 1,804 DEGs, 743 were upregulated and 1,061 were downregulated. GO and KEGG analyses showed that the DEGs were enriched in immunity and osteogenesis inhibition, and the core genes identified by the PPI network were enriched in the Hedgehog pathway, which plays a role in inflammation and tissue repair; the MEF2 transcription factor family was predicted by IRegulon. Conclusion: By direct injection of bacterial solution into the rabbit mandible defect area, the rabbit chronic IMD model was successfully established. Based on the bioinformatics analysis, we speculate that the Hedgehog pathway and the MEF2 transcription factor family may be potential intervention targets for repairing IMD.

5.
Life (Basel) ; 13(2)2023 Feb 17.
Article in English | MEDLINE | ID: mdl-36836927

ABSTRACT

E'Jiao is a traditional Chinese medicine derived from donkey skin. E'Jiao is reported to suppress elevated bone remodelling in ovariectomised rats but its mechanism of action is not known. To bridge this research gap, the current study aims to investigate the effects of E'Jiao on skeletal mineralisation, osteocyte and WNT signalling inhibitors in ovariectomised rats. Female Sprague-Dawley rats (3 months old) were ovariectomised and supplemented with E'Jiao at 0.26 g/kg, 0.53 g/kg and 1.06 g/kg, or 1% calcium carbonate (w/v) in drinking water. The rats were euthanised after two months of supplementation and their bones were collected for Fourier-transform infrared spectroscopy, histomorphometry and protein analysis. Neither ovariectomy nor treatment affected the skeletal mineral/matrix ratio, osteocyte number, empty lacunar number, and Dickkopf-1 and sclerostin protein levels (p > 0.05). Rats treated with calcium carbonate had a higher Dickkopf-1 level than baseline (p = 0.002) and E'Jiao at 0.53 g/kg (p = 0.002). In conclusion, E'Jiao has no significant effect on skeletal mineralisation, osteocyte and WNT signalling inhibitors in ovariectomised rats. The skeletal effect of E'Jiao might not be mediated through osteocytes.

6.
Nat Commun ; 14(1): 404, 2023 Feb 01.
Article in English | MEDLINE | ID: mdl-36725856

ABSTRACT

Interstitial oxygen embrittles titanium, particularly at cryogenic temperatures, which necessitates a stringent control of oxygen content in fabricating titanium and its alloys. Here, we propose a structural strategy, via grain refinement, to alleviate this problem. Compared to a coarse-grained counterpart that is extremely brittle at 77 K, the uniform elongation of an ultrafine-grained (UFG) microstructure (grain size ~ 2.0 µm) in Ti-0.3wt.%O is successfully increased by an order of magnitude, maintaining an ultrahigh yield strength inherent to the UFG microstructure. This unique strength-ductility synergy in UFG Ti-0.3wt.%O is achieved via the combined effects of diluted grain boundary segregation of oxygen that helps to improve the grain boundary cohesive energy and enhanced dislocation activities that contribute to the excellent strain hardening ability. The present strategy will not only boost the potential applications of high strength Ti-O alloys at low temperatures, but can also be applied to other alloy systems, where interstitial solution hardening results into an undesirable loss of ductility.

7.
World J Gastroenterol ; 28(26): 3132-3149, 2022 Jul 14.
Article in English | MEDLINE | ID: mdl-36051331

ABSTRACT

BACKGROUND: The development of venous thromboembolism (VTE) is associated with high mortality among gastric cancer (GC) patients. Neutrophil extracellular traps (NETs) have been reported to correlate with the prothrombotic state in some diseases, but are rarely reported in GC patients. AIM: To investigate the effect of NETs on the development of cancer-associated thrombosis in GC patients. METHODS: The levels of NETs in blood and tissue samples of patients were analyzed by ELISA, flow cytometry, and immunofluorescence staining. NET generation and hypercoagulation of platelets and endothelial cells (ECs) in vitro were observed by immunofluorescence staining. NET procoagulant activity (PCA) was determined by fibrin formation and thrombin-antithrombin complex (TAT) assays. Thrombosis in vivo was measured in a murine model induced by flow stenosis in the inferior vena cava (IVC). RESULTS: NETs were likely to form in blood and tissue samples of GC patients compared with healthy individuals. In vitro studies showed that GC cells and their conditioned medium, but not gastric mucosal epithelial cells, stimulated NET release from neutrophils. In addition, NETs induced a hypercoagulable state of platelets by upregulating the expression of phosphatidylserine and P-selectin on the cells. Furthermore, NETs stimulated the adhesion of normal platelets on glass surfaces. Similarly, NETs triggered the conversion of ECs to hypercoagulable phenotypes by downregulating the expression of their intercellular tight junctions but upregulating that of tissue factor. Treatment of normal platelets or ECs with NETs augmented the level of plasma fibrin formation and the TAT complex. In the models of IVC stenosis, tumor-bearing mice showed a stronger ability to form thrombi, and NETs abundantly accumulated in the thrombi of tumor-bearing mice compared with control mice. Notably, the combination of deoxyribonuclease I, activated protein C, and sivelestat markedly abolished the PCA of NETs. CONCLUSION: GC-induced NETs strongly increased the risk of VTE development both in vitro and in vivo. NETs are potential therapeutic targets in the prevention and treatment of VTE in GC patients.


Subject(s)
Extracellular Traps , Stomach Neoplasms , Thrombophilia , Thrombosis , Venous Thromboembolism , Animals , Constriction, Pathologic , Endothelial Cells/metabolism , Extracellular Traps/metabolism , Fibrin , Mice , Neutrophils/metabolism , Stomach Neoplasms/complications , Stomach Neoplasms/metabolism , Thrombosis/etiology , Venous Thromboembolism/etiology , Venous Thromboembolism/metabolism
8.
J Am Chem Soc ; 144(39): 18117-18125, 2022 10 05.
Article in English | MEDLINE | ID: mdl-36135325

ABSTRACT

Using a chemical approach to crosslink functionally versatile bioeffectors (such as peptides) to native proteins of interest (POI) directly inside a living cell is a useful toolbox for chemical biologists. However, this goal has not been reached due to unsatisfactory chemoselectivity, regioselectivity, and protein selectivity in protein labeling within living cells. Herein, we report the proof of concept of a cytocompatible and highly selective photolabeling strategy using a tryptophan-specific Ru-TAP complex as a photocrosslinker. Aside from the high selectivity, the photolabeling is blue light-driven by a photoinduced electron transfer (PeT) and allows the bioeffector to bear an additional UV-responsive unit. The two different photosensitivities are demonstrated by blue light-photocrosslinking a UV-sensitive peptide to POI. Our visible light photolabeling can generate photocaged proteins for subsequent activity manipulation by UV light. Cytoskeletal dynamics regulation is demonstrated in living cells via the unprecedented POI photomanipulation and proves that our methodology opens a new avenue to endogenous protein modification.


Subject(s)
Proteins , Tryptophan , Electron Transport , Light , Peptides
10.
Zhongguo Shi Yan Xue Ye Xue Za Zhi ; 30(1): 119-125, 2022 Feb.
Article in Chinese | MEDLINE | ID: mdl-35123613

ABSTRACT

AbstractObjective: To study the clinical effect of Bazhen decoction combined with sequential treatment of chemotherapy on acute lymphoblastic leukemia patients with deficiency of Qi and Yin. METHODS: 84 acute lymphoblastic leukemia patients with deficiency of both Qi and Yin treated in the Rizhao Hospital of Traditional Chinese Medicine from January 2014 to October 2016 were selected. According to the method of random control table, the patients were divided into study group and control group, with 42 patients in each group. The patients in the control group was treated by sequentially with standard chemotherapy regimen(VDCLP + intensive chemotherapy), and the patients in the study group were treated by Bazhen decoction based on control group. The complete remission after 1 month of treatment and 3year followup mortality were compared between the patients in the two groups, the blood routine, the levels of Th17, Th22, Treg and immunoglobulin(IgA, IgG and IgM) in peripheral blood of the patients were detected, the occurrence of myelosuppression and adverse reactions were analyzed. RESULTS: The complete remission rate (90.48% vs 73.81%) after 1 month of treatment, 3year survival rate (71.79% vs 47.37%) and diseasefree survival (61.54% vs 36.84%) of the patients in the study group were significantly higher than those in the control group (P<0.05). After treatment, the levels of granulocytes, WBC, PLT, and Hb of the patients in both of the two groups were increased significantly, and the blood routine test values of the patients in the study group were significantly higher than those in the control group(P<0.05). After treatment, the levels of Th17 and Th22 of the patients in the study group were significantly higher than those in the control group, while Treg was significantly lower than those in the control group (P<0.05). The levels of IgA, IgM and IgE in peripheral blood of the patients in the study group were increased significantly after treatment, and the levels of immunoglobulin of the patients in the study group were significantly higher than those in the control group (P<0.05). The proportion of bone marrow suppression grade 0 of the patients in the study group was significantly higher than those in the control group, while the proportion of grade III was significantly lower than those in the control group, and the overall inhibition degree of the patients in the study group was lighter than those in the control group (P<0.05). The incidence of nausea and vomiting, liver and kidney injury and infection of the patients in the study group was significantly lower than those in the control group (P<0.05). CONCLUSION: Bazhen decoction can improve the blood routine and immune function of acute lymphoblastic leukemia patients with qiyin deficiency after sequential treatment, reduce bone marrow suppression and the incidence of adverse reactions, thus improving the clinical efficacy.


Subject(s)
Drugs, Chinese Herbal , Precursor Cell Lymphoblastic Leukemia-Lymphoma , Humans , Liver , Medicine, Chinese Traditional , Precursor Cell Lymphoblastic Leukemia-Lymphoma/drug therapy , Qi
11.
Nanomaterials (Basel) ; 12(1)2022 Jan 03.
Article in English | MEDLINE | ID: mdl-35010112

ABSTRACT

Prolyl hydroxylase domain-containing protein 2 (PHD2) inhibition, which stabilizes hypoxia-inducible factor (HIF)-1α and thus triggers adaptation responses to hypoxia in cells, has become an important therapeutic target. Despite the proven high potency, small-molecule PHD2 inhibitors such as IOX2 may require a nanoformulation for favorable biodistribution to reduce off-target toxicity. A liposome formulation for improving the pharmacokinetics of an encapsulated drug while allowing a targeted delivery is a viable option. This study aimed to develop an efficient loading method that can encapsulate IOX2 and other PHD2 inhibitors with similar pharmacophore features in nanosized liposomes. Driven by a transmembrane calcium acetate gradient, a nearly 100% remote loading efficiency of IOX2 into liposomes was achieved with an optimized extraliposomal solution. The electron microscopy imaging revealed that IOX2 formed nanoprecipitates inside the liposome's interior compartments after loading. For drug efficacy, liposomal IOX2 outperformed the free drug in inducing the HIF-1α levels in cell experiments, especially when using a targeting ligand. This method also enabled two clinically used inhibitors-vadadustat and roxadustat-to be loaded into liposomes with a high encapsulation efficiency, indicating its generality to load other heterocyclic glycinamide PHD2 inhibitors. We believe that the liposome formulation of PHD2 inhibitors, particularly in conjunction with active targeting, would have therapeutic potential for treating more specifically localized disease lesions.

12.
Nat Genet ; 54(1): 62-72, 2022 01.
Article in English | MEDLINE | ID: mdl-34903892

ABSTRACT

The vertebrate left-right axis is specified during embryogenesis by a transient organ: the left-right organizer (LRO). Species including fish, amphibians, rodents and humans deploy motile cilia in the LRO to break bilateral symmetry, while reptiles, birds, even-toed mammals and cetaceans are believed to have LROs without motile cilia. We searched for genes whose loss during vertebrate evolution follows this pattern and identified five genes encoding extracellular proteins, including a putative protease with hitherto unknown functions that we named ciliated left-right organizer metallopeptide (CIROP). Here, we show that CIROP is specifically expressed in ciliated LROs. In zebrafish and Xenopus, CIROP is required solely on the left side, downstream of the leftward flow, but upstream of DAND5, the first asymmetrically expressed gene. We further ascertained 21 human patients with loss-of-function CIROP mutations presenting with recessive situs anomalies. Our findings posit the existence of an ancestral genetic module that has twice disappeared during vertebrate evolution but remains essential for distinguishing left from right in humans.


Subject(s)
Biological Evolution , Body Patterning , Gene Regulatory Networks , Metalloproteases , Animals , Humans , Body Patterning/genetics , Body Patterning/physiology , Cilia/genetics , Loss of Function Mutation , Metalloproteases/genetics , Metalloproteases/physiology , Proteins/genetics , Proteins/physiology , Vertebrates/genetics
13.
BMJ Case Rep ; 14(11)2021 Nov 29.
Article in English | MEDLINE | ID: mdl-34844969

ABSTRACT

Primary amyloidosis is a rare systemic disorder often associated with multiple organ dysfunction. The most common form, light chain amyloidosis, has an estimated age-adjusted incidence of 5.1-12.8 cases per million person-years. Spine involvement is extremely uncommon. We present the case of a young Asian man with newly diagnosed amyloidosis involving the lumbar spine among multiple organs with a pathological vertebral fracture that required urgent spine surgery. We believe this is the first reported case to discuss the perianaesthetic challenges in the management of lumbar spine amyloidosis.


Subject(s)
Amyloidosis , Anesthetics , Immunoglobulin Light-chain Amyloidosis , Amyloidosis/surgery , Child , Child, Preschool , Humans , Lumbar Vertebrae/diagnostic imaging , Lumbar Vertebrae/surgery , Lumbosacral Region , Male
14.
Cell Rep ; 37(1): 109775, 2021 10 05.
Article in English | MEDLINE | ID: mdl-34610312

ABSTRACT

Motile cilia defects impair cerebrospinal fluid (CSF) flow and can cause brain and spine disorders. The development of ciliated cells, their impact on CSF flow, and their function in brain and axial morphogenesis are not fully understood. We have characterized motile ciliated cells within the zebrafish brain ventricles. We show that the ventricles undergo restructuring through development, involving a transition from mono- to multiciliated cells (MCCs) driven by gmnc. MCCs co-exist with monociliated cells and generate directional flow patterns. These ciliated cells have different developmental origins and are genetically heterogenous with respect to expression of the Foxj1 family of ciliary master regulators. Finally, we show that cilia loss from the tela choroida and choroid plexus or global perturbation of multiciliation does not affect overall brain or spine morphogenesis but results in enlarged ventricles. Our findings establish that motile ciliated cells are generated by complementary and sequential transcriptional programs to support ventricular development.


Subject(s)
Brain/metabolism , Cilia/metabolism , Ependyma/metabolism , Animals , Animals, Genetically Modified/metabolism , Brain/cytology , Brain/pathology , Cell Lineage , Cerebrospinal Fluid/physiology , Cilia/pathology , Embryo, Nonmammalian/metabolism , Ependyma/cytology , Ependyma/pathology , Forkhead Transcription Factors/genetics , Forkhead Transcription Factors/metabolism , Gene Editing , Morphogenesis , Nuclear Proteins/genetics , Nuclear Proteins/metabolism , Spine/growth & development , Spine/metabolism , Telencephalon/cytology , Telencephalon/metabolism , Telencephalon/pathology , Tubulin/metabolism , Zebrafish , Zebrafish Proteins/genetics , Zebrafish Proteins/metabolism
15.
Nat Commun ; 12(1): 6158, 2021 Oct 25.
Article in English | MEDLINE | ID: mdl-34697309

ABSTRACT

Individually, increasing the concentration of either oxygen or aluminum has a deleterious effect on the ductility of titanium alloys. For example, extremely small amounts of interstitial oxygen can severely deteriorate the tensile ductility of titanium, particularly at cryogenic temperatures. Likewise, substitutional aluminum will decrease the ductility of titanium at low-oxygen concentrations. Here, we demonstrate that, counter-intuitively, significant additions of both Al and O substantially improves both strength and ductility, with a 6-fold increase in ductility for a Ti-6Al-0.3 O alloy as compared to a Ti-0.3 O alloy. The Al and O solutes act together to increase and sustain a high strain-hardening rate by modifying the planar slip that predominates into a delocalized, three-dimensional dislocation pattern. The mechanism can be attributed to decreasing stacking fault energy by Al, modification of the "shuffle" mechanism of oxygen-dislocation interaction by the repulsive Al-O interaction in Ti, and micro-segregation of Al and O by the same cause.

16.
Nutrients ; 13(6)2021 Jun 18.
Article in English | MEDLINE | ID: mdl-34207261

ABSTRACT

Human milk (HM) is the gold standard for feeding infants but has been associated with slower growth in preterm infants compared with preterm formula. This systematic review and meta-analysis summarises the post-1990 literature to examine the effect of HM feeding on growth during the neonatal admission of preterm infants with birth weight ≤1500 g and/or born ≤28 weeks' gestation. Medline, PubMed, CINAHL, and Scopus were searched, and comparisons were grouped as exclusive human milk (EHM) vs. exclusive preterm formula (EPTF), any HM vs. EPTF, and higher vs. lower doses of HM. We selected studies that used fortified HM and compared that with a PTF; studies comparing unfortified HM and term formula were excluded. Experimental and observational studies were pooled separately. The GRADE system was used to evaluate risk of bias and certainty of evidence. Forty-four studies were included with 37 (n = 9963 infants) included in the meta-analyses. In general, due to poor quality studies, evidence of the effect of any HM feeds or higher versus lower doses of HM was inconclusive. There was a possible effect that lower doses of HM compared with higher doses of HM improved weight gain during the hospital admission, and separately, a possible effect of increased head circumference growth in infants fed EPTF vs. any HM. The clinical significance of this is unclear. There was insufficient evidence to determine the effects of an exclusive HM diet on any outcomes.


Subject(s)
Infant Nutritional Physiological Phenomena , Infant, Premature/growth & development , Infant, Very Low Birth Weight , Milk, Human , Databases, Factual , Diet , Enteral Nutrition , Humans , Infant Formula , Infant, Newborn , Weight Gain
17.
Sci Total Environ ; 792: 148439, 2021 Oct 20.
Article in English | MEDLINE | ID: mdl-34147790

ABSTRACT

Artificial dams are one of the most common hydraulic structures for mitigating debris flow disasters in alpine valley regions. However, performance alteration and failure after successive debris flows can lead to dam failure, releasing large amounts of materials within a very short time; moreover, the contribution of artificial dam failures to debris flows is poorly understood. This study quantitatively analyzed the artificial dam failure effects based on the numerical simulations of the Zhouqu '8.8' debris flow, with three scenarios: all nine dams failed (S1); no dams were ever built (S2); all nine dams remained intact (S3). The results showed that artificial dam failures had a significant amplifying effect on the magnitude of a debris flow. The maximum velocity and flow depth decreased by 20% and 11.2% if all the dams did not collapse; comparison of S1 and S2 showed that discharge and velocity at the front of the debris flow increased by 54.6% and 89%, the bulk density and yield stress increased by 3.3% and 5.7%, due to artificial dam failures. This could increase the destructive capacity of a debris flow and the possibility of a river blockage. A single artificial dam failure could locally amplify the magnitude of debris flow. Overall, on the catchment scale, the magnitude of a debris flow was dominated by topography and channel geometry, which can reduce the amplification effect of dam failures at locations where the channel was curved. However, where the channel was straight and flat, the flow velocity and discharge increased cumulatively by 3 m/s and 637 m3/s due to cascading failure. In addition, a comprehensive scheme combining ecological and engineering measures to mitigate debris flow disasters is discussed. This quantitative study is important and urgent needed to understand the amplification effect of dam failures and to implement debris flow mitigation in alpine valley regions.


Subject(s)
Disasters , Rivers , China , Engineering
18.
Nat Mater ; 20(4): 468-472, 2021 Apr.
Article in English | MEDLINE | ID: mdl-33020612

ABSTRACT

It has been known for decades that the application of pulsed direct current can significantly enhance the formability of metals. However, the detailed mechanisms of this effect have been difficult to separate from simple Joule heating. Here, we study the electroplastic deformation of Ti-Al (7 at.% Al), an alloy that is uniquely suited for uncoupling this behaviour because, contrary to most metals, it has inherently lower ductility at higher temperature. We find that during mechanical deformation, electropulsing enhances cross-slip, producing a wavy dislocation morphology, and enhances twinning, which is similar to what occurs during cryogenic deformation. As a consequence, dislocations are prevented from localizing into planar slip bands that would lead to the early failure of the alloy under tension. Our results demonstrate that this macroscopic electroplastic behaviour originates from defect-level microstructural reconfiguration that cannot be rationalized by simple Joule heating.

19.
Sci Adv ; 6(43)2020 Oct.
Article in English | MEDLINE | ID: mdl-33097543

ABSTRACT

One of the most potent examples of interstitial solute strengthening in metal alloys is the extreme sensitivity of titanium to small amounts of oxygen. Unfortunately, these small amounts of oxygen also lead to a markedly decreased ductility, which in turn drives the increased cost to purify titanium to avoid this oxygen poisoning effect. Here, we report a systematic study on the oxygen sensitivity of titanium that provides a clear mechanistic view of how oxygen impurities affect the mechanical properties of titanium. The increased slip planarity of Ti-O alloys is caused by an interstitial shuffling mechanism, which is sensitive to temperature, strain rate, and oxygen content and leads to the subsequent alteration of deformation twinning behavior. The insights from our experimental and computational work provide a rationale for the design of titanium alloys with increased tolerance to variations in interstitial content, with notable implications for more widespread use of titanium alloys.

20.
Dev Biol ; 465(2): 168-177, 2020 09 15.
Article in English | MEDLINE | ID: mdl-32735790

ABSTRACT

Multiciliated cells (MCCs) differentiate hundreds of motile cilia that beat to drive fluid movement over various kinds of epithelia. In Xenopus, mice and human, the coiled-coil containing protein Mcidas (Mci) has been shown to be a key transcriptional regulator of MCC differentiation. We have examined Mci function in the zebrafish, another model organism that is widely used to study ciliary biology. We show that zebrafish mci is expressed specifically in the developing MCCs of the kidney tubules, but surprisingly, not in those of the nasal placodes. Mci proteins lack a DNA binding domain and associate with the cell-cycle transcription factors E2f4/5 for regulating MCC-specific gene expression. We found that while the zebrafish Mci protein can complex with the E2f family members, its sequence as well as the requirement and sufficiency for MCC differentiation has diverged significantly from Mci homologues of the tetrapods. We also provide evidence that compared to Gmnc, another related coiled-coil protein that has recently been shown to regulate MCC development upstream of Mci, the Mci protein originated later within the vertebrate lineage. Based on these data, we argue that in contrast to Gmnc, which has a vital role in the genetic circuitry that drives MCC formation, the requirement of Mci, at least in the zebrafish, is not obligatory.


Subject(s)
Cilia , Gene Expression Regulation, Developmental , Kidney Tubules/embryology , Signal Transduction , Transcription Factors , Zebrafish Proteins , Zebrafish , Animals , Cell Cycle , Cilia/genetics , Cilia/metabolism , Transcription Factors/genetics , Transcription Factors/metabolism , Zebrafish/embryology , Zebrafish/genetics , Zebrafish Proteins/genetics , Zebrafish Proteins/metabolism
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