Hidden-information extraction from layered structures through terahertz imaging down to ultralow SNR.

Noninvasive inspection of layered structures has remained a long-standing challenge for time-resolved imaging techniques, where both resolution and contrast are compromised by prominent signal attenuation, interlayer reflections, and dispersion. Our method based on terahertz (THz) time-domain spectroscopy overcomes these limitations by offering fine resolution and a broadband spectrum to efficiently extract hidden structural and content information from layered structures. We exploit local symmetrical characteristics of reflected THz pulses to determine the location of each layer, and apply a statistical process in the spatiotemporal domain to enhance the image contrast. Its superior performance is evidenced by the extraction of alphabetic characters in 26-layer subwavelength papers as well as layer reconstruction and debonding inspection in the conservation of Terra-Cotta Warriors. Our method enables accurate structure reconstruction and high-contrast imaging of layered structures at ultralow signal-to-noise ratio, which holds great potential for internal inspection of cultural artifacts, electronic components, coatings, and composites with dozens of submillimeter layers.

THz absorbers with an ultrahigh Q-factor empowered by the quasi-bound states in the continuum for sensing application.

The exceptional resonances excited by symmetry-protected quasi-bound states in the continuum (QBICs) have provided significant potential in high-sensitive sensing applications. Herein, we have proposed a type of metal-insulator-metal (MIM) absorbers supported by QBIC-induced resonances, and the ideal Q-factors of QBIC-induced resonances can be enhanced up to 105 in the THz regime. The coupled mode theory and the multipole scattering theory are employed to thoroughly interpret the QBIC-induced absorption mechanism. Furthermore, the refractive index sensing capacities of the as-presented absorbers have been investigated, where the maximum values of the sensing sensitivity and figure of merit (FOM) can reach up to 187 GHz per refractive index unit and 286, respectively. Therefore, it is believed that the proposed absorbers enabled by QBIC-induced resonances hold promising potential in a broad range of highly demanding sensing applications.

Terahertz spin-selective perfect absorption enabled by quasi-bound states in the continuum.

Spin-selective absorption is broadly applicable to numerous photonic devices. Here, based on a stereoscopic full metallic resonator array, a terahertz chiral metasurface with a single-layer structure is proposed and numerically demonstrated. By employing the coupled-mode theory, we demonstrate that the chiral metasurface can near-perfectly absorb one circularly polarized wave in the quasi-bound states in the continuum-induced critical coupling region but non-resonantly reflect its counterparts. Interestingly, the linewidths and handedness of the proposed chiral metasurface can be flexibly controlled by an in-plane symmetry perturbation. Our designs might offer an alternative strategy to develop chiral metasurfaces apart from conventional methods and might stimulate many potential applications for emerging terahertz technologies.

Highly sensitive terahertz sensing with 3D-printed metasurfaces empowered by a toroidal dipole.

Highly sensitive terahertz (THz) sensing with metasurfaces has attracted considerable attention recently. However, ultrahigh sensing sensitivity remains a huge challenge for practical applications. To improve the sensitivity of these devices, herein we have proposed an out-of-plane metasurface-assisted THz sensor consisting of periodically arranged bar-like meta-atoms. Benefiting from elaborate out-of-plane structures, the proposed THz sensor with high sensing sensitivity of 325 GHz/RIU can be easily fabricated via a simple three-step fabrication process, and the maximum sensing sensitivity can be ascribed to toroidal dipole resonance-enhanced THz-matter interactions. The sensing ability of the fabricated sensor is experimentally characterized by the detection of three types of analytes. It is believed that the proposed THz sensor with ultrahigh sensing sensitivity and its fabrication method might provide great potential in emerging THz sensing applications.

Colon metastasis from hepatocellular carcinoma: a case report and literature review.

BACKGROUND: Hepatocellular carcinoma (HCC) is a malignant tumor with frequent intrahepatic metastases; extrahepatic metastases are not rare but less frequent compared to intrahepatic ones. The most frequent sites of extrahepatic metastases are the lungs, followed by the lymph nodes, bones, and adrenal glands. Case report covering gastrointestinal (GI) tract involvement from HCC is limited. CASE PRESENTATION: A 60-year-old man was referred to us in May 2019 with a diagnosis of sigmoid colon tumor. The patient had a history of HCC and had received two stages of open resections for the primary and the abdominal metastasis successively and many times of transcatheter arterial chemoembolization (TACE). The sigmoid colon tumor received Hartmann procedure after abdominal enhanced computerized tomography (CT) scan and colonoscopy, while postoperative pathology and immunohistochemistry identified it as extrahepatic colonic metastasis from HCC. CONCLUSIONS: The ratio of extrahepatic metastasis to the digestive tract was very low, and the majority was upper gastrointestinal involvement because of direct invasion or intraperitoneal implantation. TACE may be the risk factor of retrograde hematogenous metastasis to the downstream colon.

Preoperative C-reactive protein-to-albumin ratio predicts anastomotic leak in elderly patients after curative colorectal surgery.

BACKGROUND: Anastomotic leak (AL), as one of the most devastating complications, is the leading cause of mortality in colorectal cancer (CRC) patients after resection. This study was aimed to investigate potential risk factors for AL in elderly surgical CRC patients. METHODS: A total of 1068 elderly subjects who underwent elective curative colorectal surgery from 2012 to 2018 were retrospectively evaluated and enrolled into this study population. The predictive value of C-reactive protein-to-albumin ratio (CAR) for AL in surgical CRC patients was evaluated by receiver operating characteristic (ROC) curve analysis. Potential risk factors for AL were assessed by the univariate and multivariate logistic regression analyses. RESULTS: Of all the 1068 enrolled patients, 81 patients have developed AL with an incidence of 7.6% (81/1068). Preoperative CAR was an effective predictor for AL with an area under the curve (AUC) of 0.758, 95% CI of 0.700-0.817, a cut-off value of 2.44, a sensitivity of 61.09% and a specificity of 80.25%, respectively (P< 0.001). Duration of operation (OR: 2.05, 95% CI: 1.21-3.44, P= 0.013) and preoperative CAR (OR: 1.94, 95% CI: 1.21-3.11, P= 0.007) were two independent risk factors for AL by the multivariate logistic regression analysis. CONCLUSIONS: Our study indicate that preoperative CAR level and duration of operation were two independent predictors for AL among elderly surgical CRC patients.

Positioning Error Analysis and Control of a Piezo-Driven 6-DOF Micro-Positioner.

This paper presents a positioning error model and a control compensation scheme for a six-degree-of-freedom (6-DOF) micro-positioner based on a compliant mechanism and piezoelectric actuators (PZT). The positioning error model is established by means of the kinematic model of the compliant mechanism and complete differential coefficient theory, which includes the relationships between three typical errors (hysteresis, machining and measuring errors) and the total positioning error. The quantitative analysis of three errors is demonstrated through several experimental studies. Afterwards, an inverse Presiach model-based feedforward compensation of the hysteresis nonlinearity is employed by the control scheme, combined with a proportional-integral-derivative (PID) feedback controller for the compensation of machining and measuring errors. Moreover, a back propagation neural network PID (BP-PID) controller and a cerebellar model articulation controller neural network PID (CMAC-PID) controller are also adopted and compared to obtain optimal control. Taking the translational motion along the X axis as an example, the positioning errors are sharply reduced by the inverse hysteresis model with the maximum error of 12.76% and a root-mean-square error of 4.09%. In combination with the CMAC-PID controller, the errors are decreased to 0.63% and 0.23%, respectively. Hence, simulated and experimental results reveal that the proposed approach can improve the positioning accuracy of 6-DOF for the micro-positioner.

Modelling and Analysis of Characteristics of a Piezoelectric-Actuated Micro-/Nano Compliant Platform Using Bond Graph Approach.

The piezoelectric-actuated flexure-based compliant platform is commonly adopted in many fields of micro and nanotechnology. In this paper, bond graph modeling, and kinematic and dynamic characteristics of a piezoelectric-actuated micro-/nano compliant platform system are investigated. During modeling, the bond graph model of the piezoelectric actuator (PZT) is derived by considering both the electrical domain and the mechanical domain. Considering the compliances of flexure hinges and elastic linkages, as well as the input ends, the bond graph model for the bridge-type displacement amplification mechanism in the compliant platform is established by combining pseudo-rigid-body (PRB) model theory and elastic beam theory. Based on the interactions between the PZT subsystem and compliant platform subsystem, the kinematic performance of the proposed compliant platform system is evaluated through both computer simulations and experimental tests. Furthermore, the frequency responses, dynamic responses and load capacity of the compliant platform system are studied. This paper explores a new modeling method for a piezoelectric-actuated compliant platform system, which can provide an effective solution when analyzing the micro-/nano system.

[Distribution characteristics and risk factors of colorectal adenomas].

OBJECTIVE: To determine the detection rate and distribution characteristics of colorectal adenomas in Ningbo area of China, and to identify the risk factors for colorectal adenoma, in order to provide reference for colorectal cancer screening. METHODS: A cross-sectional study was performed among 8660 subjects undergoing colonoscopy in the Ningbo No.2 Hospital between January and December 2016, using a questionnaire, including demographic data (age, gender, height and weight), history of diseases (diabetes, hypertension, hyperlipidemia, and family history of malignant neoplasm), lifestyle (smoking, alcohol, dietary bias on red meat, dietary bias on fruit and vegetables, dietary frequency of pickled food and physical activities), and intestinal early warning symptoms. All colonoscopically detected polyps were removed for histological examination. Polyps were histologically divided into non-adenomatous (hyperplastic polyps and inflammatory polyps) and adenomatous polyps (tubular, villous, tubulovillous and serrated adenomas). Pathologic features were analyzed according to anatomical site. Multivariate logistic regression analysis was used to identify the risk factors for colorectal adenoma. RESULTS: A total of 7077 subjects who received colonoscopic examination and completed the questionnaire survey were enrolled in this study. There were 3633 males and 3444 females with a median age of 53 (ranged 17 to 83) years. Adenoma detection rate was 15.6% (1103/7077) in all cases, 21.0%(762/3633) for males, and 9.9%(341/3444) for females(P=0.000). Detection rate of 6.2%(29/469) was recorded in individuals aged less than 30 years, 8.0%(87/1086) in those from 30 to 39 years, 12.1%(148/1222) in those from 40 to 49 years, 16.8%(272/1623) in those from 50 to 59 years, 20.4%(326/1601) in those from 60 to 69 years, and 22.4%(241/1076) in those ≥70 years. The detection rate increased according to age(P=0.000). A total of 1521 adenomas were detected in 1103 cases, including 1455 tubular adenomas, 33 tubulovillous adenomas, 9 villous adenomas and 24 serrated adenomas. Among 1521 adenomas, 44.1%(n=671) located in the right hemicolon, 39.0%(n=593) in the left hemicolon, and 16.9%(n=257) in the rectum. Significantly larger number of serrated adenomas and advanced adenomas (advanced adenoma was defined as any adenoma with high-grade intraepithelial neoplasia, diameter ≥10 mm or with villous component) was observed in the right hemicolon compared to left hemicolon and rectum [serrated adenomas: 2.5%(17/671) vs. 0.8% (5/593) and 0.8% (2/257), P=0.029; advanced adenoma: 9.2% (62/671) vs. 5.2% (31/953) and 6.6% (17/257), P=0.021]. Multivariate analysis showed that malely (P=0.003), elderly (P=0.000), obesity (P=0.014), smoking (P=0.001), alcohol (P=0.032), and family history of malignancy (P=0.000) were independent risk factors of colorectal adenoma. CONCLUSIONS: In view of a higher detection rate of colorectal adenoma in population aged 40 to 49 years especially in male individuals, the starting age of colonoscopy screening may be advanced to 40 years old. People with family history of malignancy, obesity, and habit of smoking or drinking should be regarded as important subjects for colonoscopy screening. During colonoscopy screening, special emphasis should be given to right hemicolon.

Metabolic reprogramming and AMPKα1 pathway activation by caulerpin in colorectal cancer cells.

Caulerpin, a secondary metabolite from the marine invasive green algae Caulerpa cylindracea is known to induce mitochondrial dysfunctions. In this study, the anticancer property of caulerpin was assessed in a panel of colorectal cancer cell lines. We demonstrated that caulerpin inhibited oxidative phosphorylation (OXPHOS) and facilitated an early intervention of the mitochondrial function, via inhibiting mitochondrial complex I, accompanied by the dissipation of mitochondrial membrane potential and a surge of reactive oxygen species (ROS) generation. Moreover, in response to the increment in AMP/ATP ratio, the energy sensor AMP-activated protein kinase (AMPK) was activated by caulerpin treatment in a calcium/calmodulin-dependent protein kinase 2 (CaMKK2)­dependent manner. Distinguished effect on glycolysis was observed at different time-points after caulerpin treatment. Glycolysis was enhanced after a short time treatment with caulerpin, associated with upregulation of glucose transporter 1 (GLUT1), hexokinase II (HKII) and 6-phosphofructo-2-kinase (PFKFB3) protein expressions. However, long-term activation of AMPK by caulerpin damaged the glycolysis and glucose metabolism in colorectal cells, finally causing cell death. The persistent effect of caulerpin was mediated by AMPKα1, rather than AMPKα2, to abolish cell viability through hindering mTORC1-4E-BP1 axis. Moreover, caulerpin synergized with the glycolytic inhibitor 3BP in inhibiting cellular proliferation both in vitro and in vivo. Our findings on the previously uncharacterized anticancer effects of caulerpin may provide potential therapeutic approaches targeting the colorectal carcinoma metabolism.

Nicotine enhances invasion and metastasis of human colorectal cancer cells through the nicotinic acetylcholine receptor downstream p38 MAPK signaling pathway.

Nicotine as a cigarette component is an established risk factor for colorectal cancer tumorigenesis. The downstream signaling pathways of nicotinic acetylcholine receptors (nAchRs) are believed to be responsible for the cellular effects. In the present study, we evaluated the effects and novel mechanisms for nicotine on the capacity for colorectal cancer cell invasion and metastasis. LOVO and SW620 colorectal cancer cells were stimulated with nicotine in vitro. A Transwell chamber model was applied to detect the capacity for tumor cell invasion. Assays for gelatin zymography and western blotting were applied to detect the activity and expression of metastasis-related matrix metalloproteinases (MMPs), respectively. Signal transduction was assessed by immunoblotting for the phosphorylation of relevant signal molecules and the application of pharmaceutical inhibitors. We showed that nicotine increased LOVO and SW620 colorectal cancer cell invasion along with enhanced activity and expression of MMP-1, -2 and -9. Nicotine increased phosphorylation of p38, ERK, Akt and PI3K p85 but had no effect on phosphorylation of JNK, or NF-κB. Of the pharmaceutical inhibitors of U0126 (ERK1/2 inhibitor), LY294002 (Akt activation inhibitor), SB239063 (p38 MAPK activation inhibitor) and hexamethonium (Hex) (nAchRs inhibitor), the cellular and molecular effects were reduced by the applications of SB239063 and Hex. We concluded that nicotine stimulates the invasion and metastasis of colon cancer cells in vitro via activation of the nAchRs and the p38 MAPK downstream signaling pathway. Therefore, p38 MAPK may have potential as a therapeutic target for smoking-related human colorectal cancer metastasis.