Generalized transfer matrix theory on electronic transport through graphene waveguide

In the effective mass approximation, electronic property in graphene can be characterized by the relativistic Dirac equation. Within such a continuum model we investigate the electronic transport through graphene waveguides formed by connecting multiple segments of armchair-edged graphene nanoribbons of different widths. By using appropriate wavefunction connection conditions at the junction interfaces, we generalize the conventional transfer matrix approach to formulate the linear conductance of the graphene waveguide in terms of the structure parameters and the incident electron energy. In comparison with the tight-binding calculation, we find that the generalized transfer matrix method works well in calculating the conductance spectrum of a graphene waveguide even with a complicated structure and relatively large size. The calculated conductance spectrum indicates that the graphene waveguide exhibits a well-defined insulating band around the Dirac point, even though all the constituent ribbon segments are gapless. We attribute the occurrence of the insulating band to the antiresonance effect which is intimately associated with the edge states localized at the shoulder regions of the junctions. Furthermore, such an insulating band can be sensitively shifted by a gate voltage, which suggests a device application of the graphene waveguide as an electric nanoswitch.Comment: 11 pages, 5 figure

Inhibition of PPARγ by BZ26, a GW9662 derivate, attenuated obesity-related breast cancer progression by inhibiting the reprogramming of mature adipocytes into to cancer associate adipocyte-like cells

Obesity has been associated with the development of 13 different types of cancers, including breast cancer. Evidence has indicated that cancer-associated adipocytes promote the proliferation, invasion, and metastasis of cancer. However, the mechanisms that link CAAs to the progression of obesity-related cancer are still unknown. Here, we found the mature adipocytes in the visceral fat of HFD-fed mice have a CAAs phenotype but the stromal vascular fraction of the visceral fat has not. Importantly, we found the derivate of the potent PPARγ antagonist GW9662, BZ26 inhibited the reprogramming of mature adipocytes in the visceral fat of HFD-fed mice into CAA-like cells and inhibited the proliferation and invasion of obesity-related breast cancer. Further study found that it mediated the browning of visceral, subcutaneous and perirenal fat and attenuated inflammation of adipose tissue and metabolic disorders. For the mechanism, we found that BZ26 bound and inhibited PPARγ by acting as a new modulator. Therefore, BZ26 serves as a novel modulator of PPARγ activity, that is, capable of inhibiting obesity-related breast cancer progression by inhibiting of CAA-like cell formation, suggesting that inhibiting the reprogramming of mature adipocytes into CAAs or CAA-like cells may be a potential therapeutic strategy for obesity-related cancer treatment

Extracting Global Shipping Networks from Massive Historical Automatic Identification System Sensor Data: A Bottom-Up Approach

The increasing availability of big Automatic Identification Systems (AIS) sensor data offers great opportunities to track ship activities and mine spatial-temporal patterns of ship traffic worldwide. This research proposes a data integration approach to construct Global Shipping Networks (GSN) from massive historical ship AIS trajectories in a completely bottom-up way. First, a DBSCAN (Density-Based Spatial Clustering of Applications with Noise) algorithm is applied to temporally identify relevant stop locations, such as marine terminals and their associated events. Second, the semantic meanings of these locations are obtained by mapping them to real ports as identified by the World Port Index (WPI). Stop events are leveraged to develop travel sequences of any ship between stop locations at multiple scales. Last, a GSN is constructed by considering stop locations as nodes and journeys between nodes as links. This approach generates different levels of shipping networks from the terminal, port, and country levels. It is illustrated by a case study that extracts country, port, and terminal level Global Container Shipping Networks (GCSN) from AIS trajectories of more than 4000 container ships in 2015. The main features of these GCSNs and the limitations of this work are finally discussed

Ultrasound‐controlled drug release and drug activation for cancer therapy

Abstract Traditional chemotherapy suffers from severe toxicity and side effects that limit its maximum application in cancer therapy. To overcome this challenge, an ideal treatment strategy would be to selectively control the release or regulate the activity of drugs to minimize the undesirable toxicity. Recently, ultrasound (US)‐responsive drug delivery systems (DDSs) have attracted significant attention due to the non‐invasiveness, high tissue penetration depth, and spatiotemporal controllability of US. Moreover, the US‐induced mechanical force has been proven to be a robust method to site‐selectively rearrange or cleave bonds in mechanochemistry. This review describes the US‐activated DDSs from the fundamental basics and aims to present a comprehensive summary of the current understanding of US‐responsive DDSs for controlled drug release and drug activation. First, we summarize the typical mechanisms for US‐responsive drug release and drug activation. Second, the main factors affecting the ultrasonic responsiveness of drug carriers are outlined. Furthermore, representative examples of US‐controlled drug release and drug activation are discussed, emphasizing their novelty and design principles. Finally, the challenges and an outlook on this promising therapeutic strategy are discussed

Clinicopathological characteristics of rectal multiple neuroendocrine neoplasms and literature review

Abstract Background There are only a few epidemiological reports available for reference. The clinicopathological features are not clear, so there is no consensus on treating rectal multiple neuroendocrine neoplasms. This study aims to summarize the clinicopathological characteristics and preliminarily discuss the clinical diagnosis and treatment of rectal multiple neuroendocrine neoplasms. Methods This study retrospectively analyzed rectal neuroendocrine neoplasm patients diagnosed and treated at the Fourth Hospital of Hebei Medical University from February 2007 to May 2021. The clinicopathological characteristics of rectal multiple neuroendocrine neoplasms were summarized and analyzed in combination with 14 studies on rectal multiple neuroendocrine neoplasms. Results The incidence of RM-NENs accounted for 3.8% of all R-NENs in this study. The number of tumors varied to some extent, the size of tumors was basically no more than 10 mm, and there were more G1 grade tumors. In the analysis of 46 cases with known lymph node metastasis, the difference in lymph node metastasis rate between the number of tumors < 8 and ≥ 8 was statistically significant (p = 0.002). Conclusions The incidence of rectal multiple neuroendocrine neoplasms accounted for 3.8% of all rectal neuroendocrine neoplasms. For rectal multiple neuroendocrine neoplasms, the lymph node metastasis rate was higher when the number of tumors was ≥ 8. The influence of the number of tumors on lymph node metastasis should be considered in the selection of treatment

Venous Thromboembolism and Bleeding after Transurethral Resection of the Prostate (TURP) in Patients with Preoperative Antithrombotic Therapy: A Single-Center Study from a Tertiary Hospital in China

Background: Venous thromboembolism (VTE) and postoperative hemorrhage are unavoidable complications of transurethral resection of the prostate (TURP). At present, more and more patients with benign prostate hyperplasia (BPH) need long-term antithrombotic therapy before operation due to cardiovascular diseases or cerebrovascular diseases. The purpose of this study was to investigate the effect of preoperative antithrombotic therapy history on lower extremity VTE and bleeding after TURP. Methods: Patients who underwent TURP in the Department of Urology, Xiangya Hospital, Central South University, from January 2017 to December 2021 and took antithrombotic drugs before operation were retrospectively analyzed. The baseline data of patients were collected, including age, prostate volume, preoperative International Prostate Symptom Score (IPSS), complications, surgical history within one month, indications of preoperative antithrombotic drugs, drug types, medication duration, etc. Main outcome measures included venous thromboembolism after TURP, intraoperative and postoperative bleeding, and perioperative blood transfusion. Secondary outcome measures included operation duration and postoperative hospitalization days, the duration of stopping antithrombotic drugs before operation, the recovery time of antithrombotic drugs after operation, the condition of lower limbs within 3 months after operation, major adverse cardiac events (MACEs), and cerebrovascular complications and death. Results: A total of 31 patients after TURP with a long preoperative history of antithrombotic drugs were included in this study. Six patients (19.4%) developed superficial venous thrombosis (SVT) postoperatively. Four of these patients progressed to deep vein thrombosis (DVT) without pulmonary thromboembolism (PE). Only one patient underwent extra bladder irrigation due to blockage of their urinary catheter by a blood clot postoperatively. The symptoms of hematuria mostly disappeared within one month postoperatively and lasted for up to three months postoperatively. No blood transfusion, surgical intervention to stop bleeding, lower limb discomfort such as swelling, MACEs, cerebrovascular complications, or death occurred in all patients within three months after surgery. Conclusion: Short-term preoperative discontinuation may help patients with antithrombotic therapy to obtain a relatively safe opportunity for TURP surgery after professional evaluation of perioperative conditions. The risks of perioperative bleeding, VTE, and serious cardiovascular and cerebrovascular complications are relatively controllable. It is essential for urologists to pay more attention to the perioperative management of these patients. However, further high-quality research results are needed for more powerful verification

A New Strategy to Improve the Toughness of Epoxy Thermosets—By Introducing Poly(ether nitrile ketone)s Containing Phthalazinone Structures

As high brittleness limits the application of all epoxy resins (EP), here, it can be modified by high-performance thermoplastic poly(ether nitrile ketone) containing phthalazinone structures (PPENK). Therefore, the influence of different PPENK contents on the mechanical, thermal, and low-temperature properties of EP was comprehensively investigated in this paper. The binary blend of PPENK/EP exhibited excellent properties due to homogeneous mixing and good interaction. The presence of PPENK significantly improved the mechanical properties of EP, showing 131.0%, 14.2%, and 10.0% increases in impact, tensile, and flexural strength, respectively. Morphological studies revealed that the crack deflection and bridging in PPENK were the main toughening mechanism in the blend systems. In addition, the PPENK/EP blends showed excellent thermal and low-temperature properties (−183 °C). The glass transition temperatures of the PPENK/EP blends were enhanced by approximately 50 °C. The 15 phr of the PPENK/EP blends had a low-temperature flexural strength of up to 230 MPa, which was 46.5% higher than EP. Furthermore, all blends exhibited better thermal stability

Chemiluminescence Immunoassay for S‑Adenosylhomocysteine Detection and Its Application in DNA Methyltransferase Activity Evaluation and Inhibitors Screening

Aberrant methylation by DNA transferase is associated with cancer initiation and progression. For high-throughput screening of DNA methyltransferase (MTase) activity and its inhibitors, a novel chemiluminescence immunoassay (CLIA) was established to detect S-adenosylhomocysteine (SAH), the product of S-adenosylmethionine (SAM) transmethylation reactions. We synthesized two kinds of immunogens for SAH and characterized the polyclonal antibodies in each group. The antibody with higher titer was used to develop a competitive CLIA for SAH, in which SAH in samples would compete with SAH coated on microplate in binding with SAH antibodies. Successively, horseradish peroxidase labeled goat antirabbit IgG (HRP-IgG) was conjugated with SAH antibodies on the microplate. In substrate solution containing luminol and H₂O₂, HRP-IgG catalyzed luminol oxidation by H₂O₂, generating a high chemiluminescence signal. The method could detect as low as 9.8 ng mL^–1 SAH with little cross-reaction (3.8%) to SAM. Since higher DNA MTase activity leads to more production of SAH, a correlation between the chemiluminescence intensity and DNA MTase activity was obtained in the range from 0.1 to 8.0 U/mL of DNA MTase. The inhibition study showed that, in the presence of SAM as methyl donor, Lomeguatrib, 5-Azacytidine, and 5-Aza-2′-deoxycytidine could inhibit the DNA MTase activity with IC₅₀ values of 40.57 nM, 2.26 μM, and 0.48 μM, respectively. These results are consistent with the published studies. The proposed assay does not depend on recognizing methylated cytosines in oligonucleotides (methyl acceptor) and showed the potential as an accessible platform for sensitive detection of DNA MTase activity and screening its inhibitors