[Gastric hamartomatous inverted polyps: a clinicopathological analysis of five cases].

Objective: To investigate the endoscopic and histopathological features, diagnosis and differential diagnosis of gastric hamartomatous inverted polyp (GHIP). Methods: Five cases of GHIP were collected at the University Town Hospital of Guangdong Provincial Hospital of Chinese Medicine, Guangzhou, China, from May 2021 to May 2023. The endoscopic, pathological and immunohistochemical features of the 5 GHIP cases were analyzed. The relevant literature was reviewed. Results: There were 3 males and 2 females, aged from 49 to 60 years, with a mean age of 56 years. The lesions were located in the fundus and body of the stomach, and presented as polyps or masses under endoscopy. Microscopically, the lesions were mainly in the submucosa and consisted of lobulated or clustered gastric glandular epithelium surrounded by hyperplastic smooth muscle. In some areas, there were differentiated glandular elements mimicking the normal gastric mucosa. The irregularly dilated glandular elements in the center were lined by hyperplastic foveolar epithelium, while the glands in the periphery were fundic or pyloric glands. In addition, in some areas, the glands showed cystic expansion, disordered arrangement and lack of differentiation. The hyperplastic glandular epithelium included foveolar epithelium, fundic gland and pyloric gland. There were scattered neuroendocrine cells and smooth muscle bundles in the stroma. Immunohistochemically, the tumor cells were positive for MUC5AC, MUC6, Pepsinogen Ⅰ and H+/K+ ATPase ß, but negative for MUC2. The scattered neuroendocrine cells were positive for synaptophysin, and the desmin stain highlighted hyperplastic smooth muscle bundles. One case was classified as type 2 gastric inverted polyp, and 4 cases were classified as type 3. Conclusions: GHIP is a rare gastric polyp with unique histological features. It should be distinguished from inverted hyperplastic polyp, gastritis cystica profunda, adenomyoma, hyperplastic polyps and well-differentiated gastric tubular adenocarcinoma, etc. Improving the understanding of its pathogenesis and diagnostic features can help avoid misdiagnoses.

Visualization of Chiral Electronic Structure and Anomalous Optical Response in a Material with Chiral Charge Density Waves.

Chiral materials have attracted significant research interests as they exhibit intriguing physical properties, such as chiral optical response, spin-momentum locking, and chiral induced spin selectivity. Recently, layered transition metal dichalcogenide 1T-TaS_{2} has been found to host a chiral charge density wave (CDW) order. Nevertheless, the physical consequences of the chiral order, for example, in electronic structures and the optical properties, are yet to be explored. Here, we report the spectroscopic visualization of an emergent chiral electronic band structure in the CDW phase, characterized by windmill-shaped Fermi surfaces. We uncover a remarkable chirality-dependent circularly polarized Raman response due to the salient in-plane chiral symmetry of CDW, although the ordinary circular dichroism vanishes. Chiral Fermi surfaces and anomalous Raman responses coincide with the CDW transition, proving their lattice origin. Our Letter paves a path to manipulate the chiral electronic and optical properties in two-dimensional materials and explore applications in polarization optics and spintronics.

CT-guided core needle biopsy of small (≤20 mm) subpleural pulmonary lesions: value of the long transpulmonary needle path.

AIM: To evaluate the accuracy and complications of computed tomography (CT)-guided core needle biopsy (CNB) of small (≤20 mm) subpleural pulmonary lesions with the use of the long transpulmonary needle path. MATERIALS AND METHODS: A retrospective study was undertaken comprising 235 patients who underwent CT-guided CNB of small (≤20 mm) subpleural pulmonary lesions. One of two needle paths was used: a long (≥10 mm) transpulmonary needle path (n=164, group A) or a short (<10 mm) transpulmonary needle path (n=71, group B). Diagnostic accuracy, pneumothorax, and bleeding rates were compared between the two groups. RESULTS: The diagnostic accuracy in group A was significantly higher than that in group B (93.9% versus 81.7%, p=0.004), particularly in patients with 5-10 mm lesions (89.2% versus 53.3%, p=0.013). The mean length of the transpulmonary needle path was 23.9 mm in group A and 5.9 mm in group B (p<0.001). The mean number of pleural punctures in group A was 1.01 and 1.11 in group B (p=0.016), but for patients with more than one puncture, the short transpulmonary path was not associated with a higher accuracy rate. The incidence of bleeding was 22% in group A and 9.9% in group B (p=0.028). CONCLUSION: Diagnostic accuracy for small subpleural pulmonary lesions with the use of the long transpulmonary needle path was higher than that with the use of the short transpulmonary needle path, especially for 5-10 mm lesions; however, the long transpulmonary needle path was associated with a higher rate of bleeding.

Optimal parameters and location for diffusion tensor imaging in the diagnosis of carpal tunnel syndrome: a meta-analysis.

AIM: To assess the diagnostic value of the apparent diffusion coefficient (ADC) and fractional anisotropy (FA) of diffusion tensor imaging (DTI) at several anatomical locations in patients with carpal tunnel syndrome (CTS) to explore the optimal parameters and measurement location. MATERIALS AND METHODS: A search was conducted using the PubMed, EBSCO, Ovid, Web of Science, and Cochrane databases to identify articles relevant to this study published before September 2017. Studies were selected and included according to strict eligibility criteria. Mean differences (MD) and 95% confidence intervals (CIs) were used to compare FA and ADC values between CTS patients and healthy subjects. Potential publication bias was investigated. RESULTS: Eleven studies involving 349 CTS wrists and 278 controls were selected for the meta-analysis. A notable MD: was found for lowered FA at the level of the pisiform bone for CTS versus controls (MD: -0.11, 95% confidence interval [CI]: -1.14 to -0.07, z=5.83, p<0.001). A higher ADC was found at the pisiform bone and hamate bone levels for CTS versus controls (P: MD: 0.15, 95% CI: 0.10 to 0.20, z=5.98, p<0.001, H: MD: 0.15; 95% CI: 0.09 to 0.21, z=4.67, p<0.001). CONCLUSIONS: The meta-analysis demonstrated a significant FA reduction and ADC increase in CTS patients. This result supports the use of DTI parameters in differentiating CTS patients from health subjects. The anatomical site for FA at the pisiform and ADC at the pisiform and hamate levels were more accessible than other sites for the diagnosis of CTS patients.

Evolution of the Fermi surface of Weyl semimetals in the transition metal pnictide family.

Topological Weyl semimetals (TWSs) represent a novel state of topological quantum matter which not only possesses Weyl fermions (massless chiral particles that can be viewed as magnetic monopoles in momentum space) in the bulk and unique Fermi arcs generated by topological surface states, but also exhibits appealing physical properties such as extremely large magnetoresistance and ultra-high carrier mobility. Here, by performing angle-resolved photoemission spectroscopy (ARPES) on NbP and TaP, we directly observed their band structures with characteristic Fermi arcs of TWSs. Furthermore, by systematically investigating NbP, TaP and TaAs from the same transition metal monopnictide family, we discovered their Fermiology evolution with spin-orbit coupling (SOC) strength. Our experimental findings not only reveal the mechanism to realize and fine-tune the electronic structures of TWSs, but also provide a rich material base for exploring many exotic physical phenomena (for example, chiral magnetic effects, negative magnetoresistance, and the quantum anomalous Hall effect) and novel future applications.

[Evaluation of three methods for constructing craniofacial mid-sagittal plane based on the cone beam computed tomography].

OBJECTIVE: To compare the accuracyof interactive closet point (ICP) algorithm, Procrustes analysis (PA) algorithm,and a landmark-independent method to construct the mid-sagittal plane (MSP) of the cone beam computed tomography.To provide theoretical basis for establishing coordinate systemof CBCT images and symmetric analysis. METHODS: Ten patients were selected and scanned by CBCT before orthodontic treatment.The scan data was imported into Mimics 10.0 to reconstructthree dimensional skulls.And the MSP of each skull was generated by ICP algorithm, PA algorithm and landmark-independent method. MSP extracted by ICP algorithm or PA algorithm involvedthree steps. First, the 3D skull processing was performed by reverse engineering software geomagic studio 2012 to obtain the mirror skull. Then, the original and its mirror skull was registered separately by ICP algorithm in geomagic studio 2012 and PA algorithm in NX Imageware 11.0. Finally, the registered data were united into new data to calculate the MSP of the originaldata in geomagic studio 2012. The mid-sagittal plane was determined by SELLA (S), nasion (N), basion (Ba) as traditional landmark-dependent methodconducted in software InVivoDental 5.0. The distance from 9 pairs of symmetric anatomical marked points to three sagittal plane were measured and calculated to compare the differences of the absolute value. The one-way ANOVA test was used to analyze the variable differences among the 3 MSPs. The pairwise comparison was performed with LSD method. RESULTS: MSPs calculated by the three methods were available for clinic analysis, which could be concluded from the front view.However, there was significant differences among the distances from the 9 pairs of symmetric anatomical marked points to the MSPs (F=10.932,P=0.001).LSD test showed there was no significant difference between the ICP algorithm and landmark-independent method (P=0.11), while there was significant difference between the PA algorithm and landmark-independent methods (P=0.01) . CONCLUSION: Mid-sagittal plane of 3D skulls could be generated base on ICP algorithm or PA algorithm. There was no significant difference between the ICP algorithm and landmark-independent method. For the subjects with no evident asymmetry, ICP algorithm is feasible in clinical analysis.

Signature of Strong Spin-Orbital Coupling in the Large Nonsaturating Magnetoresistance Material WTe2.

We report the detailed electronic structure of WTe2 by high resolution angle-resolved photoemission spectroscopy. We resolved a rather complicated Fermi surface of WTe2. Specifically, there are in total nine Fermi pockets, including one hole pocket at the Brillouin zone center Γ, and two hole pockets and two electron pockets on each side of Γ along the Γ-X direction. Remarkably, we have observed circular dichroism in our photoemission spectra, which suggests that the orbital angular momentum exhibits a rich texture at various sections of the Fermi surface. This is further confirmed by our density-functional-theory calculations, where the spin texture is qualitatively reproduced as the conjugate consequence of spin-orbital coupling. Since the spin texture would forbid backscatterings that are directly involved in the resistivity, our data suggest that the spin-orbit coupling and the related spin and orbital angular momentum textures may play an important role in the anomalously large magnetoresistance of WTe2. Furthermore, the large differences among spin textures calculated for magnetic fields along the in-plane and out-of-plane directions also provide a natural explanation of the large field-direction dependence on the magnetoresistance.

Usefulness of normal saline for sealing the needle track after CT-guided lung biopsy.

AIM: To determine whether the use of normal saline for sealing the needle track can reduce the incidence of pneumothorax and chest tube placement after computed tomography (CT)-guided lung biopsy. MATERIALS AND METHODS: A prospective, randomised, controlled trial enrolling 322 patients was conducted. All patients were randomly assigned to one of two groups: those in whom the needle track was not sealed with normal saline (n=161, Group A) and those who did receive normal saline (n=161, Group B). CT-guided biopsy was performed with coaxial technique. Normal saline, which ranged from 1-3 ml, was injected while the trocar needle was being withdrawn. Patient characteristics, lesion, and procedure variables were analysed as potential risk variables for occurrence of pneumothorax and chest tube placement. RESULTS: The incidence of pneumothorax was 26.1% in Group A and 6.2% in Group B (p<0.001). Nine patients in Group A and one patient in Group B required chest tube placement (p=0.010). Using multiple logistic regression analysis, smaller lesion size, greater needle-pleural angle, longer lesion-pleural distance, presence of emphysema, and no sealing the needle track with normal saline were significantly associated with an increased risk of pneumothorax, and that the latter three factors were also associated with an increased risk of pneumothorax requiring chest tube placement. CONLUSION: Normal saline for sealing the needle track significantly reduces the incidence of pneumothorax and prevents subsequent chest tube placement after CT-guided lung biopsy.

[Comparison of two kinds of methods evaluating the degree of facial asymmetry by three-dimensional data].

OBJECTIVE: To compare two digital methods of quantitatively accessing the degree of facial asymmetry by three-dimensional data. METHODS: The three-dimensional data of 20 subjects were got by the FaceScan, and then were input to the reverse engineering software Imageware 13.0 and Geomagic 12. Their mirror data were acquired and superimposed with the original data by the methods of interactive closest points (ICP) and Procrustes analysis (PA). The mid-sagittal planes of the two methods were extracted respectively, the degree of facial asymmetry and the distance of 21 automatic landmarks to mid-sagittal plane were calculated and compared. RESULTS: The paired t test was taken and t=1.346, P=0.193. CONCLUSION: We can safely come to the conclusions that for the subjects with no evident facial asymmetry, there are no significant difference between the PA and the ICP methods for extracting the mid-sagittal plane from three-dimensional data.

Can diffusion-weighted imaging be used to differentiate brain abscess from other ring-enhancing brain lesions? A meta-analysis.

AIM: To explore the role of diffusion-weighted imaging (DWI) in the discrimination of brain abscess from other ring-enhancing brain lesions through meta-analysis. MATERIALS AND METHODS: The PUMBED, OVID, and China National Knowledge Infrastructure (CNKI) databases, from January 1995 to March 2013, were searched for studies evaluating the diagnostic performance of DWI in the discrimination of brain abscess lesions. Using the data collected, pooled sensitivities and specificities across studies were determined, positive and negative likelihood ratios (LR) were calculated, and summary receiver operating characteristic (SROC) curves were constructed. RESULTS: A total of 11 studies fulfilled all of the inclusion criteria and were considered for the analysis. The pooled sensitivity values and pooled specificity values including 95% confidence intervals (CI) were 0.95 (0.87-0.98) and 0.94 (0.88-0.97). The pooled positive LR (95% CI) was 4.13(2.55-6.7); the pooled negative LR (95% CI) was 0.01 (0-1.7); and the area under the curve of the symmetric SROC was 0.98. CONCLUSIONS: DWI has high sensitivity and specificity for the differentiation of brain abscess from other intracranial cystic mass lesions.

Factors influencing diagnostic yield of CT-guided percutaneous core needle biopsy for bone lesions.

AIM: To evaluate the factors influencing diagnostic yield of computed tomography (CT)-guided percutaneous core needle biopsy (CNB) for bone lesions. MATERIALS AND METHODS: Between September 2005 and July 2011, 162 consecutive CT-guided CNB procedures were performed in 155 patients. The variables analysed were age, sex, lesion location, lesion type, lesion size, specimen size, biopsy needle gauge, and individual radiologist. The factors influencing diagnostic yield of CT-guided percutaneous CNB for bone lesions were determined by multivariate analysis of variables. RESULTS: The diagnostic yield was 81.5%. Diagnostic yield was 89.9% for lytic bone lesions and 48.5% for sclerotic bone lesions (p < 0.001), and 89.2% for lesions ≥3 cm and 73.4% for lesions <3 cm (p = 0.010). The significant factors influencing diagnostic yield of CT-guided percutaneous CNB for bone lesions were lesion type [p < 0.001; odds ratio (OR) for a lytic lesion was approximately 12 times higher than that for a sclerotic lesion; 95% confidence interval (CI): 4.22-34.01], and lesion size (p = 0.012; OR for a lesion size ≥3 cm was about five-times higher than that for a lesion size <3 cm; 95% CI: 1.42-16.71). CONCLUSION: Lesion type and lesion size are determining factors in diagnostic yield. The higher diagnostic yield is correlated with lytic lesion and lesion size ≥3 cm.

CT-guided percutaneous core needle biopsy for small (≤20 mm) pulmonary lesions.

AIM: To assess the accuracy and risk factors for complications of computed tomography (CT)-guided percutaneous core needle biopsy (CNB) for small (≤20 mm) pulmonary lesions. MATERIALS AND METHODS: A retrospective study was undertaken comprising 169 patients who underwent CT-guided CNB for small (≤20 mm) pulmonary lesions. To assess the accuracy of the procedure, the diagnosis at biopsy was compared with the diagnosis after definitive surgery or clinical follow-up. The risk factors for pneumothorax and bleeding were determined by multivariate analysis of variables. RESULTS: The overall diagnostic accuracy was 93.5%. The sensitivity for malignancy and specificity for benign lesions were 90.4% and 100%, respectively. Positive and negative predictive values were 100% and 83.3%, respectively. Twenty-five patients (14.8%) had pneumothorax after CT percutaneous CNB of the lung. The significant risk factors affecting the incidence of pneumothorax were lesion-pleural distance (p = 0.008) and needle-pleural angle (p = 0.012). The highest rate of pneumothorax correlated with a lesion-pleural distance ≥21 mm (OR = 18.46; 95%CI: 2.27-149.95) and a needle-pleural angle ≥51° (OR = 8.22; 95%CI: 2.14-31.49). Bleeding occurred in 30 patients (17.8%). The only significant risk factor affecting the incidence of bleeding was lesion-pleural distance (p = 0.011). The highest bleeding rate correlated with a lesion-pleural distance ≥21 mm (OR = 7.93; 95%CI: 1.73-36.43). CONCLUSION: CT-guided percutaneous CNB of small (≤20 mm) pulmonary lesions provides high diagnostic accuracy with acceptable complications. A lesion-pleural distance of ≥21 mm and needle-pleural angle of ≥51° are identified as the risk factors for highest pneumothorax rate. In addition, the needle-pleural angle is a novel predictor of pneumothorax. A lesion-pleural distance of ≥21 mm is also identified as a risk factor for the highest bleeding rate.

[Association between different obesity measurement indexes and serum C-reactive protein in adult women].

Objective: To explore the association of different obesity measurement indexes on serum C-reactive protein (CRP) in Chinese adult women. Methods: The data were obtained from baseline and follow-up surveys of the urban Breast Cancer Screening Program in Shuangliu District, Chengdu. A total of 441 adult women were included in the study. A questionnaire survey, physical examination, and laboratory testing were conducted on the subjects. Multivariate logistic regression model, two-level mixed effects logistic regression model, and restricted cubic spline method were used to investigate the linear and nonlinear correlation between different obesity measurement indexes and serum CRP in adult women. Results: For every 1 unit increase in BMI, waist circumference (WC), and adiposity, the risk of elevated serum CRP or exacerbation of chronic low-grade inflammation in adult women increased by 16.5%, 5.0%, and 11.1% (P<0.05), respectively. Both BMI and adiposity were nonlinear correlated with serum CRP. Using BMI=24.0 kg/m2 as the reference point, serum CRP level increased with the increase of BMI when BMI >24.0 kg/m2. Using adiposity=30% as the reference point, serum CRP level increased with the increase of adiposity when adiposity >30%. Conclusions: Overall, obesity reflected by BMI had the strongest association with serum CRP in adult women, followed by body fat content reflected by adiposity, and central obesity reflected by WC had the weakest association with CRP. Adult women with BMI >24.0 kg/m2 or adiposity >30% are at high risk for obesity-related inflammatory manifestations.

Few-layer graphene direct deposition on Ni and Cu foil by cold-wall chemical vapor deposition.

We report an alternative synthesis process, cold-wall thermal chemical vapor deposition (CVD), is replied to directly deposit single-layer and few-layer graphene films on Ar plasma treated Ni and Cu foils using CH4 as carbon source. Through optimizing the process parameters, large scale single-layer graphene grown on Ni foil is comparable to that grown on Cu foil. The graphene films were able to be transferred to other substrates such as SiO2/Si, flexible transparent PET and verified by optical microscopy, Raman microscopy and scanning electron microscopy. The sheet resistance and transmission of the transferred graphene films on PET substrate were also discussed.

LncRNA ANRIL regulates cell proliferation and migration via sponging miR-339-5p and regulating FRS2 expression in atherosclerosis.

OBJECTIVE: Atherosclerosis (AS), with high risk of stroke or cerebrovascular disease, is one of the most common causes of death worldwide. Increasing evidence shows that long non-coding RNA (lncRNA) antisense non-coding RNA in the INK4 locus (ANRIL) is related to atherothrombotic stroke susceptibility and contributes to AS progression. However, the underlying mechanism was not explained yet. PATIENTS AND METHODS: Human aorta vascular smooth muscle cells (HA-VSMCs) and human umbilical vein endothelial cells (HUVECs) were treated with oxidized Low Density Lipoprotein (ox-LDL) and considered as AS cell models. Quantitative reverse transcriptase PCR (qRT-PCR) and Western blotting were employed to investigate the mRNA and protein expression level, respectively. Microscopic examination through fluorescent in situ hybridization (FISH) was used to determine the location of ANRIL. Cell proliferation and migration assays were demonstrated to evaluate the functional role of ANRIL in AS. Potential target of ANRIL was determined using Luciferase reporter assay and RNA immunoprecipitation (RIP). RESULTS: ANRIL was upregulated and miR-399-5p was down-regulated in both human atherosclerotic plaques and ox-LDL-induced cells. ANRIL was located in cytoplasm and promoted cell proliferation and migration by sponging miR-399-5p. Further analysis identified fibroblast growth factor receptor substrate 2 (FRS2) as a direct target of miR-399-5p. Finally, RAS/RAF/ERK signal pathway was proved to be involved in the regulation of ANRIL on the progression of AS. CONCLUSIONS: These results revealed the underlying mechanism that ANRIL promoted AS progression by sponging miR-399-5p and regulating RAS/RAF/ERK signal pathway, suggesting that ANRIL might be a potential target for the therapeutic strategy of AS.

Pharmacokinetics of diclofenac sodium injection in swine.

The pharmacokinetics of a diclofenac sodium was investigated in swine. A single intravenous (i.v.) or intramuscular (i.m.) injection of 5% diclofenac sodium (concentration = 2.5 mg · kg-1) was administered to 8 healthy pigs according to a two-period crossover design. The pharmacokinetic parameters were calculated by non-compartmental analysis with DAS2.1.1 software. After a single i.v. administration, the main pharmacokinetic parameters of diclofenac sodium injection in swine were as follows: the elimination half-time (T1/2ß) was 1.32±0.34 h; the area under the curve (AUC) was (55.50±5.50 µg · mL-1 h; the mean residence time (MRT) was 1.60±0.28 h; the apparent volume of distribution (Vd) was 0.50±0.05 L · kg-1; and the body clearance (CLB) was 0.26±0.04 L · (h · kg)-1. After the single i.m. administration, the pharmacokinetic parameters were as follows: peak time (Tmax) was 1.19±0.26 h; and peak concentration (Cmax) was 11.61±5.99 µg mL-1. The diclofenac sodium has the following pharmacokinetic characteristics in swine: rapid absorption and elimination; high peak concentration; and bioavailability.

Topological Lifshitz transitions and Fermi arc manipulation in Weyl semimetal NbAs.

Surface Fermi arcs (SFAs), the unique open Fermi-surfaces (FSs) discovered recently in topological Weyl semimetals (TWSs), are unlike closed FSs in conventional materials and can give rise to many exotic phenomena, such as anomalous SFA-mediated quantum oscillations, chiral magnetic effects, three-dimensional quantum Hall effect, non-local voltage generation and anomalous electromagnetic wave transmission. Here, by using in-situ surface decoration, we demonstrate successful manipulation of the shape, size and even the connections of SFAs in a model TWS, NbAs, and observe their evolution that leads to an unusual topological Lifshitz transition not caused by the change of the carrier concentration. The phase transition teleports the SFAs between different parts of the surface Brillouin zone. Despite the dramatic surface evolution, the existence of SFAs is robust and each SFA remains tied to a pair of Weyl points of opposite chirality, as dictated by the bulk topology.

Regional Values of Diffusional Kurtosis Estimates in the Healthy Brain during Normal Aging.

OBJECTIVE: To provide estimates of the diffusional kurtosis in different anatomical regions of a healthy brain and to assess age dependency of diffusion kurtosis imaging (DKI) and diffusion tensor imaging (DTI) derived parametric values in these regions. MATERIALS AND METHODS: Eighty healthy volunteers underwent DKI of the brain with 3.0 T magnetic resonance imaging. The DKI was obtained by using three b values of 0, 1000, 2000 s/mm2, and with 50 diffusion directions. The regions of interest-based measurements were calculated to obtain several DKI estimates of 21 different locations of brain, and then, the age dependency for DKI- and DTI-derived parameters in these regions were assessed by using linear and nonlinear regressions. RESULTS: The mean kurtosis varied from 0.73 ± 0.01 (head of caudate nucleus) to 1.07 ± 0.08 (splenium of corpus callosum (CC)). The radial kurtosis varied from 0.84 ± 0.06 (head of caudate nucleus) to 1.05 ± 0.07 (splenium of CC), and axial kurtosis from 0.41 ± 0.02 (genu of CC) to 0.78 ± 0.02 (pallidum). DTI-derived parametric values also varied across the region. Age dependence was found for DKI-derived parameters in almost all measured regions except for corona radiata and centrum semiovale. On the contrary, DTI failed to show age dependency in many regions including gray matter structure. CONCLUSION: In conclusion, the knowledge of range of diffusion kurtosis parameters in each anatomical region in different age group is important before its clinical application to diagnose the pathology.

Erosion potential of the Yangtze Delta under sediment starvation and climate change.

Deltas are widely threatened by sediment starvation and climate change. Erosion potential is an important indicator of delta vulnerability. Here, we investigate the erosion potential of the Yangtze Delta. We found that over the past half century the Yangtze's sediment discharge has decreased by 80% due to the construction of >50,000 dams and soil conservation, whereas the wind speed and wave height in the delta region have increased by 5-7%, and the sea level has risen at a rate of 3 mm/yr. According to hydrodynamic measurements and analyses of seabed sediments, the period when bed shear stress due to combined current-wave action under normal weather conditions exceeds the critical bed shear stress for erosion (τ cr ) accounts for 63% of the total observed period on average and can reach 100% during peak storms. This explains why net erosion has occurred in some areas of the subaqueous delta. We also found that the increase with depth of τ cr is very gradual in the uppermost several metres of the depositional sequence. We therefore expect that the Yangtze subaqueous delta will experience continuous erosion under sediment starvation and climate change in the next decades of this century or even a few centuries.