Exploring the surface-enhanced Raman scattering (SERS) activity of gold nanostructures embedded around nanogaps at wafer scale: Simulations and experiments

A unique way of converting free space light into a local electromagnetic field in small spaces is via metallic nanostructuring. In this work fabrication, experimental characterization and simulation of surface-enhanced Raman scattering (SERS) active specimens based on Au nanostructures are discussed. We used displacement Talbot lithography (DTL) to fabricate silicon nano-wedge substrates with Au nanostructures embedded around their apices. After the ion beam etching process, a nanogap is introduced between two Au nanostructures templated over nano-wedges, yielding specimens with SERS characteristics. The Au nanostructures and the nanogaps have symmetric and asymmetric configurations with respect to the wedges. With this nanofabrication method, various wafer-scale specimens were fabricated with highly controllable nanogaps with a size in the order of 6 nm for symmetric gaps and 8 nm for asymmetric gaps. SERS characteristics of these specimens were analyzed experimentally by calculating their analytical enhancement factor (AEF). According to finite-difference time-domain (FDTD) simulations, the Raman enhancement arises at the narrow gap due to plasmonic resonances, yielding a maximum AEF of 6.9 × 106. The results highlight the SERS activity of the nanostructures and ultimately comply with reliable substrates for practical applications

Integration of selectively grown topological insulator nanoribbons in superconducting quantum circuits

We report on the precise integration of nm-scale topological insulator Josephson junctions into mm-scale superconducting quantum circuits via selective area epitaxy and local stencil lithography. By studying dielectric losses of superconducting microwave resonators fabricated on top of our selective area growth mask, we verify the compatibility of this in situ technique with microwave applications. We probe the microwave response of on-chip microwave cavities coupled to topological insulator-shunted superconducting qubit devices and observe a power dependence that indicates nonlinear qubit behaviour. Our method enables integration of complex networks of topological insulator nanostructures into superconducting circuits, paving the way for both novel voltage-controlled Josephson and topological qubits.Comment: 11 pages, 6 figure

Released micromachined beams utilizing laterally uniform porosity porous silicon

© 2014, Sun et al.; licensee Springer. Abstract: Suspended micromachined porous silicon beams with laterally uniform porosity are reported, which have been fabricated using standard photolithography processes designed for compatibility with complementary metal-oxide-semiconductor (CMOS) processes. Anodization, annealing, reactive ion etching, repeated photolithography, lift off and electropolishing processes were used to release patterned porous silicon microbeams on a Si substrate. This is the first time that micromachined, suspended PS microbeams have been demonstrated with laterally uniform porosity, well-defined anchors and flat surfaces. PACS: 81.16.-c; 81.16.Nd; 81.16.R

Early Last Interglacial ocean warming drove substantial ice mass loss from Antarctica

The future response of the Antarctic ice sheet to rising temperatures remains highly uncertain. A useful period for assessing the sensitivity of Antarctica to warming is the Last Interglacial (LIG) (129 to 116 ky), which experienced warmer polar temperatures and higher global mean sea level (GMSL) (+6 to 9 m) relative to present day. LIG sea level cannot be fully explained by Greenland Ice Sheet melt (∼2 m), ocean thermal expansion, and melting mountain glaciers (∼1 m), suggesting substantial Antarctic mass loss was initiated by warming of Southern Ocean waters, resulting from a weakening Atlantic meridional overturning circulation in response to North Atlantic surface freshening. Here, we report a blue-ice record of ice sheet and environmental change from the Weddell Sea Embayment at the periphery of the marine-based West Antarctic Ice Sheet (WAIS), which is underlain by major methane hydrate reserves. Constrained by a widespread volcanic horizon and supported by ancient microbial DNA analyses, we provide evidence for substantial mass loss across the Weddell Sea embayment during the LIG, most likely driven by ocean warming and associated with destabilization of subglacial hydrates. Ice sheet modeling supports this interpretation and suggests that millennial-scale warming of the Southern Ocean could have triggered a multimeter rise in global sea levels. Our data indicate that Antarctica is highly vulnerable to projected increases in ocean temperatures and may drive ice–climate feedbacks that further amplify warming

Níveis de lisina digestível em rações, em que se manteve ou não a relação aminoacídica, para frangos de corte de 1 a 21 dias de idade, mantidos em estresse por calor

Dois ensaios foram conduzidos para avaliar os efeitos de níveis de lisina digestível em rações em que se manteve ou não a relação aminoacídica sobre o desempenho de frangos de corte machos de 1 a 21 dias de idade, criados em alta temperatura. O delineamento experimental utilizado em ambos os ensaios foi o inteiramente casualizado. As aves, no ensaio 1, foram distribuídas em cinco tratamentos (0,92; 0,98; 1,04; 1,10 e 1,16% de lisina digestível em ração convencional), oito repetições e dez aves por repetição. No ensaio 2, os frangos foram distribuídos em quatro tratamentos (1,04; 1,10; 1,16 e 1,22% de lisina digestível em rações mantendo a relação aminoacídica), oito repetições e dez aves por repetição. No ensaio 1, os tratamentos influenciaram quadraticamente o ganho de peso e o consumo de ração, que aumentaram até os níveis de 1,14 e 1,09% de lisina, respectivamente. Embora a conversão alimentar tenha melhorado de forma linear, o modelo LRP foi o que melhor se ajustou aos dados, estimando em 1,097% o nível de lisina a partir do qual ocorreu um platô. Não houve efeito dos tratamentos sobre os pesos absolutos do coração, fígado e intestinos, enquanto o peso absoluto da moela aumentou linearmente. O peso absoluto da carcaça aumentou, enquanto os pesos relativos do coração e do fígado reduziram quadraticamente com os tratamentos. No ensaio 2, os tratamentos influenciaram de forma linear crescente o ganho de peso e a conversão alimentar, enquanto o consumo de ração não variou. Os tratamentos influenciaram linearmente o peso absoluto da carcaça, enquanto os pesos absoluto e relativo das vísceras não variaram. Concluiu-se que frangos de corte machos, de 1 a 21 dias de idade, mantidos em estresse por calor, exigem, no mínimo, 1,14 e 1,22% de lisina digestível em ração convencional e em ração em que se manteve a relação aminoacídica, respectivamente.Two trials were conducted to evaluate the effects of digestible lysine levels in diets maintaining or not the relationship of amino acids, on performance of broilers from 1 to 21 days, kept under heat stress. A completely randomized experimental design was used in both trials. In the trial 1, the broilers were allotted in five treatments (0.92; 0.98; 1.04; 1.10 and 1.16% of lysine in conventional diets), eight replicates and ten broilers per replicate. In the trial 2, the broilers were allotted in four treatments (1.04; 1.10; 1.16 and 1.22% of lysine in diet maintaining the relationship of amino acids), eight replicates and ten broilers per replicate. In the trial 1, the digestible lysine levels influenced quadraticly the weight gain and the feed intake that increased up to 1.14 and 1.09%, respectively. Although feed:gain ratio had changed by linear way, the LRP model adjusted better to the data, estimating in 1.097% the lysine level where occurred a "plateau". There was no effect of treatments on absolute weights of heart, liver and intestines, while the absolute weight of gizzard increased linearly. The absolute weight of carcass increased while the relative weights of heart and liver reduced quadraticly. In the trial 2, the treatments influenced in a crescent linear way the weight gain and the feed:gain ratio while the feed intake was not influenced. The treatments influenced linearly the absolute weight of carcass while the absolute and relative weights of the organs were not influenced. It was concluded that male broilers, in the period from 1 to 21 days of age, kept under heat stress, require at least 1.14 and 1.22% of digestible lysine in conventional diet and in diet maintaining the relationship of amino acid, respectively