Metascreen-Based Acoustic Passive Phased Array

Conventional phased arrays require a large number of sources in forming a complex wave front, resulting in complexity and a high cost to operate the individual sources. We present a passive phased array using an acoustic metascreen that transmits sound energy from a single source and steers the transmitted wave front to form the desired fields. The metascreen is composed of elements that have a discrete resolution along the screen at an order smaller than the wavelength, allowing for fine wave-front shaping beyond the paraxial approximation. The performance is verified in experiment by forming a self-bending beam. Our metascreen-based passive array with its simplicity and capability has applications in places where conventional active arrays are complex and have limitations.Acoustical Society of AmericaNational Basic Research Program of China (973 Program) 2010CB327803 2012CB921504National Natural Science Foundation of China 11174138 11174139 11222442 81127901 11274168Physic

Enterprise Credit Evaluating Model Study

Accurate enterprise credit evaluating can efficiently avoid the asymmetry of the information which the finance institute transferred ,on the other hand ,the enterprise can bring the financing cost down. According to the loan examine and approve work of our country and stock industry bank, the index system of ECE is constructed. Then, a new Enterprise Credit Evaluating Model Based on Gray theory and fuzzy mathematics is proposed. Finally, a example is given and the result show good reliability. Keywords: ECE (Enterprise Credit Evaluate), Gray System Theory, White function, AHM（Attribute Hierarchical Model）, FCE(Fuzzy Comprehensive Evaluate) Résumé L’évaluation précise du crédit d’entreprises peut d’un côté éviter de façon efficace l’asymétrie de la transmission des informations des institutions financières, de l’autre, elle peut permettre aux entreprises de baisser les coûts financiers. Cette thèse relie ensemble la vérification et l’approbation du crédit de la banque du commerce nationalisée et de la banque industrielle par société anonyme pour créer un système d’évaluation du crédit d’entreprises( ECE). Selon les théories d’évaluation grises basées sur AHM et des méthodes des mathématiques ambigues, elle a fait une proposition d’un nouveau modèle d’évaluation qualitative et quantitative. Enfin, un exemplaire est donné et le résultat nous montre une bonne crédibilité et précision. Mots-clés: ECE (évaluation du crédit d’entreprises), théorie d’évaluation grise, fonction blanche, AHM（modèle d’attribuation hiérarchique）, FCE(méthodes des mathématiques ambigues) 摘 要 準確的企業資信評級一方面可以有效的避免對金融機構資訊傳遞的非對稱性，另一方面企業也可以降低融資成本。文章結合我國國有商業銀行和股份制商業銀行信貸審批工作，構建企業資信評估指標體系，通過基於 AHM的灰色評價理論和模糊數學的方法，提出了一種新的定性和定量相結合的評價模型，實證結果表明，該模型得到的企業資信評級結果有較高的可信度和準確度。關鍵詞：資信評級；屬性層次；白化權函數；灰色評價；模糊綜合評

Decrease in inner retinal thickness at para- and perifoveal areas before vascular retinopathy in patients with metabolic risk factors

AbstractBackgroundHypertension, dyslipidemia, and hyperglycemia are major risk factors for vascular retinopathy. The relationship between retinal thickness at the macular area and metabolic risk factors, as well as visual impairment, in elderly patients before developing vascular occlusion needs to be investigated.MethodsIn this prospective, case-control study, patients >60 years old, without objective visual threatened ocular diseases or systemic abnormalities, except for hypertension, dyslipidemia or/and hyperglycemia, were included for measurement of retinal thickness at the macular area by optical coherence tomography (OCT).ResultsFifty-four patients were analyzed; 11 patients had no metabolic risk factors, 16 had one, 17 had two, and 10 had three. There was no significant difference in age, and full and outer retinal thickness, but there was a significantly lower inner retinal thickness at the parafoveal (p = 0.0013) and perifoveal (p = 0.018) areas in patients with at least one metabolic risk factor. The superior (p = 0.040) and inferior (p = 0.046) inner retina at the perifovea and superior (p = 0.013) inner retinal thickness at the parafovea were sensitive to metabolic abnormalities. Only patients with three factors had significantly reduced best corrected visual acuity (BCVA).ConclusionElderly patients with metabolic risk factors had decreased inner retinal thickness at the para- and perifoveal areas before retinal vascular diseases. Accelerated inner retinal degeneration occurred prior to visual impairment

Graphene oxide nanoparticles for enhanced photothermal cancer cell therapy under the irradiation of a femtosecond laser beam

Nano-sized graphene and graphene oxide (GO) are promising for biomedical applications, such as drug delivery and photothermal therapy of cancer. It is observed in thiswork that the ultrafast reduction of GO nanoparticles (GONs)with a femtosecond laser beam creates extensive microbubbling. To understand the surface chemistry of GONs on the microbubble formation, the GONs were reduced to remove most of the oxygen-containing groups to get reduced GONs (rGONs). Microbubbling was not observed when the rGONs were irradiated by the laser. The instant collapse of the microbubbles may produce microcavitation effect that brings about localized mechanical damage. To understand the potential applications of this phenomenon, cancer cells labeled with GONs or rGONs were irradiated with the laser. Interestingly, the microbubbling effect greatly facilitated the destruction of cancer cells. When microbubbles were produced, the effective laser power was reduced to less than half of what is needed when microbubbling is absent. This finding will contribute to the safe application of femtosecond laser in the medical area by taking advantage of the ultrafast reduction of GONs. It may also find other important applications that need highly localized microcavitation effects