Broadband thin sound absorber based on hybrid labyrinthine metastructures with optimally designed parameters.

Broadband acoustic absorbers with thin thickness are highly desired in practical situations such as architectural acoustics, yet it is still challenging to achieve high absorption by using structure with limited thickness. Here we report the theoretical optimal design, numerical simulation and experimental demonstration of a planar acoustic absorber capable of producing broadband sound absorption with deep-subwavelength thickness. The mechanism is that, we use a hybrid design of individual unit cell comprising multiple resonators with a coiled configuration for expanding the working bandwidth and downscaling the resulting device, and, on the other hand, the geometries of the constituent resonance elements are optimally designed by using genetic algorithm. Based on an analytical formula we derive for an efficient prediction of the absorption efficiency, the optimization process is accelerated and gives rise to an optimally maximized amount of absorbed energy with limited device thickness. As a result, the proposed absorber features planar profile, broad bandwidth, wide absorbing angle (the absorber works well when the incident angle of sound wave reaches 60°) and thin thickness (< 1/25 wavelength). In addition, the proposed scheme does not rely on extra sound-absorptive materials or the type of constituent solid material, which significantly simplifies the sample fabrication and improves the application potential of resulting device. The measured data agree well with the theoretical predictions, showing high sound absorption in the prescribed frequency range. We envision our design to further improve the performance of acoustic absorbers and find applications in practical situations in need of elimination of broadband acoustic waves within limited spaces.

Enantioselective bioaccumulation of diniconazole in Tenebrio molitor larvae.

The enantioselective bioaccumulation of diniconazole in Tenebrio molitor Linne larva was investigated with liquid chromatography tandem mass spectrometry based on the ChiralcelOD-3R[cellulose tri-(3,5-dimethylphenyl carbamate)] column. In this study we documented the effects of dietary supplementation with wheat bran contaminated by racemic diniconazole at two dose levels of 20 mg kg(-1) and 2 mg kg(-1) (dry weight) in Tenebrio molitor. The results showed that both doses of diniconazole were taken up by Tenebrio molitor rapidly in the first few days, the concentrations of R-enantiomer and S-enantiomer at high doses reached the highest level of 0.55 mg kg(-1) and 0.48 mg kg(-1) , respectively, on the 1(st) d, and the concentrations of them obtained a maxima of 0.129 mg kg(-1) and 0.128 mg kg(-1) at low dose, respectively, on the 3(rd) d, which means that the concentration of diniconazole was proportional to the time of achieving the highest accumulated level. It afterwards attained equilibrium after a sharp decline at both 20 mg kg(-1) and 2 mg kg(-1) of diniconazole. The determination results from the feces of Tenebrio molitor demonstrated that the extraction recovery (ER) values of the high dose group were higher than that of the low dose group and the values were all above 1; therefore, it could be inferred that enantiomerization existed in Tenebrio molitor. Additionally, the biota accumulation factor was used to evaluate the bioaccumulation of diniconazole enantiomers, showing that the bioaccumulation of diniconazole in Tenebrio molitor was enantioselective with preferential accumulation of S-enantiomer.

Serum miR-21 expression in human esophageal squamous cell carcinomas.

To investigate the relationship between serum miRNA-21 (miR-21) expression in esophageal squamous cell carcinomas (ESCCs) and their clinicopathologic features, a 1:1 matched case-control study including 21 patients with ESCC and 21 age- and gender-matched healthy controls was carried out. Serum specimens were taken from all subjects. Total RNA was extracted and the stem-loop real time polymerase chain reaction was used to measure serum miR-21 in both groups. Clinical parameters were assessed to determine associations with serum miR-21 concentrations. Serum miR-21 expression in ESCC samples was significantly higher than in paired cancer-free samples (P <0.05). Metastasis was associated with mir-21 expression in serum (P <0.05), ESCC patients with metastasis having 8.4-fold higher serum miR-21 concentrations than healthy controls. There were no statistically significant associations between miR-21 expression and clinicopathologic parameters, such as gender (P >0.05), age (P >0.05), tumor location (P >0.05), cell differentiation (P >0.05), TNM staging (P >0.05), whether chemo/radiotherapy had been administered (P >0.05), or whether surgery had been performed (P >0.05). These findings suggest that the detection of microRNA-21 in serum might serve as a new tumor biomarker in diagnosis and assessment of prognosis of ESCCs.

Alteration of the pancreatic endocrine component in the early stage of acute necrotic pancreatitis in rats.

OBJECTIVE: To investigate alterations of the pancreatic endocrine component in the early stage of acute necrotic pancreatitis (ANP) in rats. METHODS: Thirty-six Sprague-Dawley rats were randomly allocated to two groups: ANP group (n = 18) and sham-operated (control) group (n = 18). ANP was induced by retrograde injection of 4% sodium deoxycholate (40 mg/kg, 0.1 mL/min) into the biliopancreatic duct and the severity of pancreatitis induced was assessed by histopathological examination and level of plasma amylase. The pancreatic endocrine function was assessed by measuring the levels of plasma glucose and insulin and by measuring the insulin content in pancreatic beta cells by immunofluorescence and immunocytochemistry. RESULTS: Five hours after operation, the pancreas of rats in the ANP group showed pathological changes with edema, hemorrhage, fatty necrosis, acinar destruction and leukocyte infiltration in the exocrine portion of the pancreas. Plasma amylase activity increased significantly (P < 0.01) and bloody ascites appeared in the abdominal cavity. Nevertheless the endocrine islets appeared normal and the beta cells contained intensive labeling of insulin. Levels of glucose and insulin in plasma increased significantly. In the ANP group, 5 h after operation the plasma level of glucose was 8.18 +/- 2.26 mmol/L vs 6.39 +/- 1.26 mmol/L, and of insulin was 23.27 +/- 3.50 MIU/L vs 18.40 +/- 3.98 MIU/L. In the control group, 5 h after operation the plasma level of glucose was 9.39 +/- 0.62 mmol/L vs 5.89 +/- 0.62 mmol/L, and of insulin was 26.28 +/- 4.77 MIU/L vs 12.89 +/- 2.05 MIU/L; there was no significant difference between these two groups (P > 0.05). After a bolus injection of glucose, however, a much higher level of insulin was found in the control group (35.30 +/- 5.05 MIU/L) than that in the ANP group (23.91 +/- 4.62 MIU/L, P < 0.05). CONCLUSIONS: There may be an impaired ability of insulin release in response to glucose stimulation in the early stage of ANP, although the morphology of the pancreatic endocrine component remains intact.

Intronic enhancement of angiotensin II type 2 receptor transgene expression in vitro and in vivo.

The angiotensin II type 2 receptor (AT2R) can influence a variety of intracellular signaling molecules and cellular functions. However, its physiological functions and the roles of introns in the regulation of its expression have not been well determined. We first demonstrated that both intron 1 and intron 2 of AT2R could significantly enhance AT2R overexpression. Thus, we have provided some new prerequisites for further studies on the mechanisms that control AT2R gene expression. Next, we established a highly efficient method of delivering this receptor in vitro and in vivo using an AT2R recombinant adenoviral vector containing two introns of the AT2R. The vector may be useful in helping to uncover AT2R physiological functions and also for gene therapy related to AT2R. Moreover, we determined the important role of introns in gene expression cassettes and the inconsistency of expression between the targeted gene and the reporter gene.

Adenoviral-mediated neuron specific transduction of angiotensin II type 2 receptors.

The angiotensin II (Ang II) type 2 receptor (AT2R) is localized at specific nuclei within adult rat brain. However, a lack of specific approaches for manipulating the activity of neuronal AT2R has meant that the physiological actions of these sites in the brain remain to be established. Therefore, in this study, our aim was to develop a method by which AT2R can be specifically overexpressed in neurons and in rat brain, with the ultimate goal of a producing a system where discrete increases in AT2R levels in brain nuclei could reveal (and be linked to) physiological actions. Here, we have constructed an AT2R recombinant adenoviral vector, Ad5-SYN-AT2R-IRES-EGFP, which contains the AT2R gene and an IRES-linked EGFP reporter gene, both driven by the neuron-specific synapsin I (SYN) gene promoter. This vector efficiently transduces the AT2R into neuronal cells in culture and results in the expression of high levels of AT2R. These expressed receptors are functional in terms of inhibition of Erk mitogen activated protein kinases (Erk MAPK) and stimulation of neuronal K+ current. Furthermore, microinjection of this vector into adult rat brain elicits a long lasting ( approximately 1 month) expression of AT2R within neurons. In summary, we have developed a viral vector that can be used for the efficient transduction of AT2R into neurons both in vitro and in vivo, the use of which may help to define the physiological functions of brain AT2R in adult rats.