G-Quadruplex/Hemin-Mediated Polarity-Switchable and Photocurrent-Amplified System for Escherichia coli O157:H7 Detection.

The contamination of food by pathogens is a serious problem in global food safety, and current methods of detection are costly, time-consuming, and cumbersome. Therefore, it is necessary to develop rapid, portable, and sensitive assays for foodborne pathogens. In addition, assays for foodborne pathogens must be resistant to interference resulting from the complex food matrix to prevent false positives and negatives. In this study, hemin and reduced graphene oxide-MoS2 sheets (GMS) were used to design a near-infrared (NIR)-responsive photoelectrochemical (PEC) aptasensor with target-induced photocurrent polarity switching based on a hairpin aptamer (Hp) with a G-quadruplex motif. A ready-to-use analytical device was developed by immobilizing GMS on the surface of a commercial screen-printed electrode, followed by the attachment of the aptamer. In the presence of Escherichia coli O157:H7, the binding sites of Hp with the G-quadruplex motif were opened and exposed to hemin, leading to the formation of a G-quadruplex/hemin DNAzyme. Crucially, after binding to hemin, the charge transfer pathway of GMS changes, resulting in a switch of the photocurrent polarity. Further, G-quadruplex/hemin DNAzyme enhanced the cathodic photocurrent, and the proposed sensor exhibited a wide linear range ((25.0-1.0) × 107 CFU/mL), a low limit of detection (2.0 CFU/mL), and good anti-interference performance. These findings expand the applications of NIR-responsive PEC materials and provide versatile PEC methods for detecting biological analytes, especially for food safety testing.

Shape Prediction of the Sheet in Continuous Roll Forming Based on the Analysis of Exit Velocity.

Continuous roll forming (CRF) is a new technology that combines continuous forming and multi-point forming to produce three-dimensional (3D) curved surfaces. Compared with other methods, the equipment of CRF is very simple, including only a pair of bendable work rolls and the corresponding shape adjustment and support assembly. By controlling the bending shapes of the upper and lower rolls and the size of the roll gap during forming, double curvature surfaces with different shapes can be produced. In this paper, a simplified expression of the exit velocity of the sheet is provided, and the formulas for the calculation of the longitudinal curvature radius are further derived. The reason for the discrepancy between the actual and predicted values of the longitudinal radius is deeply discussed from the perspective of the distribution of the exit velocity. By using the response surface methodology, the effects of the maximum compression ratio, the sheet width, the sheet thickness, and the transverse curvature radius on the longitudinal curvature radius are analyzed. Meanwhile, the correction coefficients of the predicted formulas for the positive and negative Gaussian curvature surfaces are obtained as 1.138 and 0.905, respectively. The validity and practicability of the modified formulas are verified by numerical simulations and forming experiments.

Macrospirocyclic oligomer based on triphenylamine and diphenylphosphine oxide as a bipolar host for efficient blue electrophosphorescent organic light-emitting diodes (OLEDs).

A novel bipolar oligomer (TPA-PO)3 was prepared as a host material for efficient blue phosphorescent organic light-emitting diodes (OLEDs). Through the C-9s of the fluorene units, three triphenylamine units attached to diphenylphosphine oxide are connected in series to form a macrocyclic structure. The solution-processed phosphorescent device based on FIrpic and (TPA-PO)3 achieved a maximum current efficiency of 19.4 cd A(-1) and a maximum luminance of 11,500 cd m(-2) with a relatively low efficiency roll-off.

Iliofemoral deep vein thrombosis after tibial plateau fracture fixation related to undiagnosed May-Thurner syndrome: a case report.

BACKGROUND: May-Thurner Syndrome (MTS) represents an anatomic variation of the iliac vessels, in which the left common iliac vein is compressed by an overriding iliac artery. Patients with this abnormality are predisposed to the formation of a left-sided iliofemoral deep venous thrombosis (DVT). While DVT is a familiar complication in the setting of lower extremity trauma, there are no previous reports of MTS complicating the care of patients requiring orthopaedic surgery. CASE PRESENTATION: We present the case of an extensive limb-threatening DVT in a patient with previously undiagnosed MTS, resulting after internal fixation of a left tibial plateau fracture. Four days after surgery, despite standard prophylactic anticoagulation, the patient developed an extensive occlusive DVT, extending from the common iliac vein to the popliteal vein. Successful diagnosis required a CT venogram in addition to standard lower extremity ultrasound exam. Severe lower extremity edema continued to worsen despite formal anticoagulation. Urgent mechanical thrombolysis was undertaken, followed by staged catheter-directed thrombolysis with recombinant tissue plasminogen activator (rTPA) and intraluminal stenting. Following this treatment, the patient was noted to have gradual but dramatic resolution of his lower extremity edema and swelling. CONCLUSION: The present case demonstrates the potential danger that may accompany MTS in the setting of lower extremity trauma. When an extensive left lower extremity DVT complicates the care of a patient with extremity trauma, clinicians should have a low threshold to pursue the diagnosis of MTS with advanced imaging studies. Venography remains the gold standard in diagnosis, but CT and MRI venography are less invasive and should allow for accurate diagnosis. In this case, formal anticoagulation proved to be ineffective, and endovascular intervention was required.

Macrospirocyclic oligomers based on carbazole and fluorene.

Monodisperse macrospirocyclic oligomers were prepared using self-condensation of the Friedel-Crafts reaction. Through the C-9s of the central fluorene units of four surrounding oligofluorenes, four carbazole units are connected in a series to form a macrocyclic core. These rodlike oligofluorenes form a rigid three-dimensional structure, affording the resulting macrocyclics a high steric hindrance for close interchain packing.

Phospholipase cbeta is critical for T cell chemotaxis.

Chemokines acting through G protein-coupled receptors play an essential role in the immune response. PI3K and phospholipase C (PLC) are distinct signaling molecules that have been proposed in the regulation of chemokine-mediated cell migration. Studies with knockout mice have demonstrated a critical role for PI3K in G(alphai) protein-coupled receptor-mediated neutrophil and lymphocyte chemotaxis. Although PLCbeta is not essential for the chemotactic response of neutrophils, its role in lymphocyte migration has not been clearly defined. We compared the chemotactic response of peripheral T cells derived from wild-type mice with mice containing loss-of-function mutations in both of the two predominant lymphocyte PLCbeta isoforms (PLCbeta2 and PLCbeta3), and demonstrate that loss of PLCbeta2 and PLCbeta3 significantly impaired T cell migration. Because second messengers generated by PLCbeta lead to a rise in intracellular calcium and activation of PKC, we analyzed which of these responses was critical for the PLCbeta-mediated chemotaxis. Intracellular calcium chelation decreased the chemotactic response of wild-type lymphocytes, but pharmacologic inhibition of several PKC isoforms had no effect. Furthermore, calcium efflux induced by stromal cell-derived factor-1alpha was undetectable in PLCbeta2beta3-null lymphocytes, suggesting that the migration defect is due to the impaired ability to increase intracellular calcium. This study demonstrates that, in contrast to neutrophils, phospholipid second messengers generated by PLCbeta play a critical role in T lymphocyte chemotaxis.