DNA folding and melting observed in real time redefine the energy landscape

We report real-time observations of the folding and melting of DNA by probing two active sites of a hairpin structure, the bases and the stem end, and using an ultrafast T-jump. Studies at different initial temperatures (before, during, and after melting) provide the time scale of water heating (<20 ps), single-strand destacking (700 ps to 2 ns), and hairpin destacking (microseconds and longer) in solutions of various ionic strengths and pH values. The behavior of transient changes gives direct evidence to the existence of intermediate collapsed structures, labile in destacking but compact in nature, and indicates that melting is not a two-state process. We propose a landscape that is defined by these nucleation structures and destacking for efficient folding and melting

Numerical simulation of circulating tumor cell separation in a dielectrophoresis based Y-Y shaped microfluidic device

Efficient and effective separation of circulating tumor cells from biological samples to promote early diagnosis of cancer is important but challenging, especially for non-small cell lung cancer (NSCLC). In this article, a Y-Y shaped microfluidic device was designed to isolate NSCLC cells with a dielectrophoresis approach. Numerical simulations were conducted that the trajectories of cells were traced by solving the electric potential distribution and the flow field in a microchannel. The effects of inlet flow rate ratio of blood sample and buffer on separation performance were studied and optimized by the numerical investigation. Under optimal operating conditions, the separation efficiency can reach around 99%, which is achieved with 100 kHz AC, electrodes potential ranging from 1.6 V to 2.2 V, and flow rate ratio from 1.9 to 2.5. This study presents a potentially efficient, facile and low-cost route for circulating tumor cell separation

Mid-frequency prediction of transmission loss using a novel hybrid deterministic and statistical method

A novel hybrid deterministic-statistical approach named ES-FE-SEA method specially used to predict the sound Transmission loss of panels in mid-frequency is proposed in this paper. The proposed hybrid methods takes the best advantages of edged-based smoothing FEM (ES-FEM) and statistical energy analysis (SEA) to further improve the accuracy of mid-frequency transmission loss predictions. The application of ES-FEM will “soften” the well-known “overly-stiff” behavior in the standard FEM solution and reduce the inherent numerical dispersion error. While the SEA approach will deal with the physical uncertainty in the relatively higher frequency range. Two different types of subsystems will be coupled based on “reciprocity relationship” theorem. The proposed was firstly applied to a standard simple numerical example, and excellent agreement with reference results was achieved. Thus the method is then applied to a more complicated model-a 2D dash panel in a car. The proposed ES-FE-SEA is verified by various numerical examples

Poorly cohesive duodenal carcinoma mixed with signet ring cell carcinoma with systemic metastasis: a case report and literature review

Poorly cohesive duodenal carcinoma mixed with signet ring cell carcinoma is very rare, and no cases have been reported. When distant metastasis occurs, it is very easy to be misdiagnosed. We report the first case of a 52-year-old man with poorly cohesive carcinoma of the duodenum mixed with signet ring cell carcinoma with systemic metastasis. The process of its diagnosis and differential diagnosis is highlighted

Omega-3 fatty acids supplementation restores mechanisms that maintain brain homeostasis in traumatic brain injury

ABSTRACT Traumatic brain injury (TBI) produces a state of vulnerability that reduces the brain capacity to cope with secondary insults. The silent information regulator 2 (Sir2) has been implicated with maintaining genomic stability and cellular homeostasis under challenging situation. Here we explore the possibility that the action of Sir2␣ (mammalian Sir2) in the brain can extend to serve neuronal plasticity. We provide novel evidence showing that mild TBI reduces the expression of Sir2␣ in the hippocampus, in proportion to increased levels of protein oxidation. In addition, we show that dietary supplementation of omega-3 fatty acids that ameliorates protein oxidation was effective to reverse the reduction of Sir2␣ level in injured rats. Given that oxidative stress is a subproduct of dysfunctional energy homeostasis, we measured AMP-activated protein kinase (AMPK) and phosphorylated-AMPK (p-AMPK) to have an indication of the energy status of cells. Hippocampal levels of total and phosphorylated AMPK were reduced after TBI and levels were normalized by omega-3 fatty acts supplements. Further, we found that TBI reduced ubiquitous mitochondrial creatine kinase (uMtCK), an enzyme implicated in the energetic regulation of Ca 2؉ -pumps and in the maintenance of Ca 2؉ -homeostasis. Omega-3 fatty acids supplements normalized the levels of uMtCK after lesion. Furthermore, we found that the correlation between Sir2␣ and AMPK or p-AMPK was disrupted by TBI, but restored by omega-3 fatty acids supplements. Our results suggest that TBI may compromise neuronal protective mechanisms by involving the action of Sir2␣. In addition, results show the capacity of omega-3 fatty acids to counteract some of the effects of TBI by normalizing levels of molecular systems associated with energy homeostasis

Multivariable Super Twisting Based Robust Trajectory Tracking Control for Small Unmanned Helicopter

This paper presents a highly robust trajectory tracking controller for small unmanned helicopter with model uncertainties and external disturbances. First, a simplified dynamic model is developed, where the model uncertainties and external disturbances are treated as compounded disturbances. Then the system is divided into three interconnected subsystems: altitude subsystem, yaw subsystem, and horizontal subsystem. Second, a disturbance observer based controller (DOBC) is designed based upon backstepping and multivariable super twisting control algorithm to obtain robust trajectory tracking property. A sliding mode observer works as an estimator of the compounded disturbances. In order to lessen calculative burden, a first-order exact differentiator is employed to estimate the time derivative of the virtual control. Moreover, proof of the stability of the closed-loop system based on Lyapunov method is given. Finally, simulation results are presented to illustrate the effectiveness and robustness of the proposed flight control scheme