Spiral-shaped Structures Research Articles

Surface Plasmon Transmission Line Based on Folded Stepped Grooves and Spiral-Shaped Structures

Surface Plasmon Transmission Line Based on Folded Stepped Grooves and Spiral-Shaped Structures

Growing human-scale scala tympani-like in vitro cell constructs

Emerging materials and electrode technologies have potential to revolutionise development of higher resolution next-generation, bionic devices. However, barriers associated with the extended timescales, regulatory constraints, and opportunity costs of preclinical and clinical studies, can inhibit such innovation. Development of in vitro models that mimic human tissues would provide an enabling platform to overcome many of these barriers in the product development pathway. This research aimed to develop human-scale tissue engineered cochlea models for high throughput evaluation of cochlear implants on the bench. Novel mould-casting techniques and stereolithography three-dimensional (3D) printing approaches to template hydrogels into spiral-shaped structures resembling the scala tympani were compared. While hydrogels are typically exploited to support 3D tissue-like structures, the challenge lies in developing irregular morphologies like the scala tympani, in which the cochlear electrodes are commonly implanted. This study successfully developed human-scale scala tympani-like hydrogel structures that support viable cell adhesion and can accommodate cochlear implants for future device testing.

Nearly 30,000 Late-type Main-sequence Stars with Stellar Age from LAMOST DR5

Abstract We construct a sample of nearly 30,000 main-sequence stars with 4500 K < T eff < 5000 K and stellar ages estimated by the chromospheric activity−age relation. This sample is used to determine the age distribution in the R–Z plane of the Galaxy, where R is the projected Galactocentric distance in the disk midplane and Z is the height above the disk midplane. As ∣Z∣ increases, the percentage of old stars becomes larger. It is known that scale-height of Galactic disk increases as R increases, which is called a flare. A mild flare from R ∼ 8.0 to 9.0 kpc in stellar age distribution is found. We also find that the velocity dispersion increases with age as confirmed by previous studies. Finally we present spiral-shaped structures in Z–υ Z phase space in three stellar age bins. The spiral is clearly seen in the age bin of [0, 1] Gyr, which suggests that a vertical perturbation to the disk probably took place within the last ∼1.0 Gyr.

The History of Spirals, the Foundation of Herbal Compositions, in our Traditional Arts

Kainattaki herşey oran ve orantı sistemleri üzerine yaratılmıştır. Bir çok varlığın yapısında bulunan helezonlar da bu oransal harmoniyi barındırarak oluşmuş sarmal biçimli yapılardır. Sanatçılar kâinattaki bu mükemmelliği yansıtmak istemiş ve İlahî Oranlar’ı eserlerinde uygulamaya çalışmışlardır. Yüzyıllardır farklı sanat dallarında kullanılan helezonlar geleneksel sanatlarımızdaki bitkisel kompozisyonların temelinde de yer almaktadır. Helezonların tarihçesi insanlık tarihi kadar eskidir. Sanatçılar tabiatı gözlemleyerek, sabır ve yetenekleriyle mükemmel tasarımlar oluşturmuşlardır. Kompozisyonların kusursuzluğu kullanılan oranlara bağlıdır. Sanatçılar bu uyum ve dengeyi helezonlarla sağlamışlardır. Makalemizde, geleneksel sanatlarımızda kullanılan bitkisel kompozisyonların temel taşını oluşturan helezonların tarihçesine ışık tutmaya çalışılacaktır.

Enhancement of critical currents and photon-count rates by magnetic field in spiral superconducting nanowire single-photon detectors

We investigated the influence of magnetic fields on critical currents and photon-count rates for optical and near-infrared photons in spiral-shaped nanowire structures of different types. Nanowires with a width of about 100 nm were made in forms of square and circular spirals with a pitch of 150 nm. Magnetic field dependencies of the critical current in square spirals were asymmetric with respect to the field direction. In the current maximum, we achieved a more than 6 percent increase of the critical current. Contrary, circular spirals showed fully symmetric dependencies with the current maximum at zero magnetic field. Photon-count rates of spirals have been studied in the wavelength range from 500 to 1400 nm at magnetic fields up to 500 mT. In circular spirals, the rates of photon and dark counts were symmetric in magnetic fields at all achievable experimental conditions. In square spirals, dark and photon count rates are asymmetric with the minima occurring at opposite directions of the field. Dark count rates are lower than 10 cps at bias currents up to 90 percent of the critical value in the whole range of applied magnetic fields. Based on our results, we propose a way to decrease the minimum detectable photon flux by applying external magnetic field to the detector.

Soft Matter and Optical Vortices: A Good Match for New Science and Technology

The interaction of soft materials with optical vortices can give rise to exciting new science and technology. In this paper, I will review a few recent examples of research based on such combination. In particular, I will consider the recently demonstrated applications of the liquid crystal “q-plates” to quantum communication without the need to align the reference frames of the communicating parties and to ultra-sensitive measurement of rotation angles, the latter by the new device concept dubbed “photonic gears”. Moreover, I will discuss the observation of nanometric spiral-shaped structures generated by vortex light on the surface of azopolymers.

Spiral-shaped graphoglyptids from an Early Permian intertidal flat

Spiral-shaped foraging trace fossils, assigned to the graphoglyptid cf. Spirorhaphe azteca, are reported from an Early Permian intertidal flat in the Robledo Mountains of southern New Mexico, USA. Remarkably similar spiral-shaped structures are produced in modern intertidal flats by the paraonid polychaete Paraonis fulgens, and function as traps to capture mobile microorganisms migrating in the sediment in response to tides. We envisage a similar function for the Early Permian trace fossils. Previous studies have suggested that the lack of P. fulgens‐type traces from ancient intertidal deposits indicates that such behavior only evolved geologically recently in such settings. However, this report demonstrates that such specialized foraging behavior was present in intertidal settings by at least the Early Permian. Graphoglyptids are typical of deep-marine settings, and characteristic of the Nereites ichnofacies. This represents their first undoubted occurrence in intertidal facies in the geological record. We postulate that the occurrence of graphoglyptids in deep-marine and intertidal settings is related to the predictability of resources. The scarcity of intertidal graphoglyptids in the geological record is most likely a preservational effect.

Bacterial mitosis: partitioning protein ParA oscillates in spiral-shaped structures and positions plasmids at mid-cell.

The par2 locus of Escherichia coli plasmid pB171 encodes oscillating ATPase ParA, DNA binding protein ParB and two cis-acting DNA regions to which ParB binds (parC1 and parC2). Three independent techniques were used to investigate the subcellular localization of plasmids carrying par2. In cells with a single plasmid focus, the focus located preferentially at mid-cell. In cells with two foci, these located at quarter-cell positions. In the absence of ParB and parC1/parC2, ParA-GFP formed stationary helices extending from one end of the nucleoid to the other. In the presence of ParB and parC1/parC2, ParA-GFP oscillated in spiral-shaped structures. Amino acid substitutions in ParA simultaneously abolished ParA spiral formation, oscillation and either plasmid localization or plasmid separation at mid-cell. Therefore, our results suggest that ParA spirals position plasmids at the middle of the bacterial nucleoid and subsequently separate them into daughter cells.

The analysis of the structuring processes in oxyhydrate gel systems

This work presents the model for the description of gel systems on the basis of the Vlasov kinetic equation. The simplified equation describing the formation of spiral-shaped structures observed in the experiments (a kind of the Liesegang rings) is obtained in some approximation as well. The quantization of the pacemaker circular radii in oxyhydrate gels observed in the experiment is explained. The authors show that molecular and quasiconvective components are the constituents of the effective coefficients of diffusion in gel systems. The superposition of the effect of different factors vibrations produces a complex periodical diffusion pattern.

Spirals in cholesteric liquid crystals: A possible nucleation initiator

The helicoidal structure of the cholesteric liquid crystal phase can be untwisted by the electric field effect. We have shown that spiral-shaped structures could nucleate at the threshold of the field-induced homeotropic state from filaments (linked to the twisted state) embedded in a homeotropic matrix (untwisted cholesteric). In this article, we describe and study what are the mechanisms involved in this phenomenon. In particular, we study to what extent the characteristics suggest a nucleation mechanism based on the propagation from the surfaces of distortions in the distribution of molecules director. These deformations propagate through the homeotropic matrix adjacent to the filaments.

SPIRAL CHOLESTERICS: SURFACE EFFECTS

The helicoidal structure of the cholesteric phase can be untwisted by the electric field effect. We have shown that spiral-shaped structures could nucleate at the threshold of the field-induced homeotropic state from filaments (linked to the twisted state) embedded in a homeotropic pseudo-nematic matrix (untwisted cholesteric). In this article, we show that confinement and anchoring conditions influence the dynamical behavior and the existence of spiral patterns induced in cholesteric liquid crystals materials by an electric field.