Transparent Structures Research Articles

Empowerment onderzoek: een kritische vriend voor sociaal werkers

Empowerment onderzoek: een kritische vriend voor sociaal werkers

Laser for vitreous floaters

SummaryBackgroundThe presence of a space between the posterior capsule and the anterior vitreous was first proposed in 1887 but difficulties inherent in examining this structure had made it impossible to visualize this area in vivo until now. Estimation of the size of this space was considered as impossible.Materials and methodsWe utilize an optical coherence tomography system attached to the Zeiss Opmi Lumera 700/Rescan microscope (Zeiss Ltd, Germany) to provide real‐time images of the Berger space, the anterior hyaloid and the ligament of Wieger.ResultsThe results of three patients show beautiful real‐time OCT images of the Berger space and of the ligament of Wieger. In one high myopic eye there was even evidence of anterior vitreous detachment (AVD).ConclusionPreviously unseen transparent structures of the eye can now be imaged intraoperatively using real‐time OCT. This technique provides information on the status of the posterior capsule but more interestingly from the anterior hyaloid and its posterior capsule attachment by the ligament of Wieger. These previously unseen changes in the anterior hyaloid may contribute to the better understanding of the posterior segment complications after cataract surgery.

The utilization of LTCC-PDMS bonding technology for microfluidic system applications – a simple fluorescent sensor

Purpose This paper aims to present a research on utilization of an irreversible bonding between non-transparent low temperature co-fired ceramics (LTCC) and transparent poly(dimethylsiloxane) (PDMS). The research presented in this paper is focused on the technology and performance of the miniature microfluidic module for fluorescence measurement. Design/methodology/approach The chemical combination of both materials is achieved through surface modification using argon-oxygen dielectric barrier discharge (DBD) plasma. According to the performed spectroscopic analyses (X-ray photoelectron spectroscopy, XPS; attenuated total reflection-Fourier infrared spectroscopy, ATR-FTIR) and contact angle measurements, the LTCC and PDMS surfaces are oxidized during the process. The presented microfluidic module was fabricated using LTCC technology. The possibility for the fabrication of LTCC-PDMS microfluidic fluorescent sensor is studied. The performance of the sensor was examined experimentally. Findings As a result of DBD plasma oxidation, the LTCC and PDMS surfaces change in character from hydrophobic to hydrophilic and were permanently bonded. The presented LTCC-PDMS bonding technique was used to fabricate a microfluidic fluorescent sensor. The preliminary measurements of the sensor have proven that it is possible to observe the fluorescence of a liquid sample from a very small volume. Research limitations/implications The presented research is a preliminary work which is focused on the fabrication of the LTCC-PDMS fluorescent sensor. The microfluidic device was positively tested only for ethanolic fluorescein solutions. Therefore, fluorescence measurements should be performed for biological specimen (e.g. DNA). Practical implications The LTCC-PDMS bonding technology combines the advantages of both materials. One the one hand, transparent PDMS with precise, transparent three-dimensional structures can be fabricated using hot embossing, soft lithography or laser ablation. On the other hand, rigid LTCC substrate consisting of microfluidic structures, electric interconnections, heaters and optoelectronic components can be fabricated. The development of the LTCC-PDMS microfluidic modules provides opportunity for the construction of a lab-on-chip, or micro-total analysis systems-type system, for analytical chemistry and fast medical diagnoses. Originality/value This paper shows utilization of the PDMS-LTCC bonding technology for microfluidics. Moreover, the design, fabrication and performance of the PDMS-LTCC fluorescent sensor are presented.

Intraoperative optical coherence tomography in corneal and glaucoma surgical procedures

Optical coherence tomography (OCT) is the clinical gold standard for anterior and posterior segment imaging. Since OCT devices have been integrated into surgical microscopes, this technique is also available intraoperatively in anterior segment surgery. OCT is well established in imaging very thin or transparent structures as they appear in corneal or glaucoma surgery. Therefore, intraoperative OCT can deliver important information for the surgeon which is superior to the normal surgical microscope. In the present work, an overview about the opportunities of intraoperative OCT in cornea and glaucoma surgery are presented. The recent literature (PubMed) and our own experience at the Center for Ophthalmology, University Hospital of Cologne are analysed. Intraoperative OCT enables real-time imaging during corneal and glaucoma surgery. Several clinical studies exist, indicating its benefit, e. g. in DMEK, DALK, DSAEK, Boston Keratoprosthesis, canaloplasty or trabectome surgery. Several structures, not visible in the surgical microscope, can be visualized using intraoperative OCT. As a real-time and high-resolution imaging device, intraoperative online OCT delivers additional information in glaucoma and corneal surgery, compared to the normal operating microscope. Nonetheless one of the main problems is the shadowing produced by surgical instruments. Today the main limitation is the lack of randomized-controlled clinical trials, evaluating the benefit of microscope-integrated intraoperative OCT, compared to the microscope.

Kimyasal yöntem ile indirgenmiş grafen oksit sentezi ve karakterizasyonu

More recently, graphene, having outstanding electrical, mechanical, thermal and optical properties, have become an important research topic. Reduced graphene oxide (RGO) is one of the most effective way to obtain the graphene. In this study, RGO was obtained by reduction of graphene oxide (GO) synthesized by a modified Hummers method. The transparent structures of RGO have been identified through SEM images. The ratio of carbon (C) was found to be approximately 89% by SEM/EDX analysis. It was proven by FT-IR analysis that hydroxyl, carbonyl, epoxy and alkoxy bonds in GO structure were removed from RGO structure. On the other hand, RAMAN spectroscopic studies showed that the new sp 2 structures occurred, and the amount of regular structures increased. XRD analysis indicated that d-spacing between the layers of RGO decreased from 0,83 nm to 0,36 nm due to the degradation of functional groups during the chemical process, which were formed in the oxidation process.

Intraoperative OCT in ophthalmic microsurgery

Recent improvements in technology have enabled integration of SD-OCT into the optical path of an operating microscope. Here we present an overview of possible applications of iOCT (intraoperative optical coherence tomography) for retinal, glaucoma and corneal surgery. iOCT-based imaging can not only improve safety and quality of the surgery but also the learning curve of the surgeon. The ability to visualize barely visible or transparent structures with iOCT has achieved a significant added value intraoperatively, particularly in macular surgery, trabeculectomy and lamellar keratoplasty. Further, systematic assessment is warranted to define the usefulness of the iOCT more precisely.

Three-Dimensional Optical Mapping of Nanoparticle Distribution in Intact Tissues.

The role of tissue architecture in mediating nanoparticle transport, targeting, and biological effects is unknown due to the lack of tools for imaging nanomaterials in whole organs. Here, we developed a rapid optical mapping technique to image nanomaterials in intact organs ex vivo and in three-dimensions (3D). We engineered a high-throughput electrophoretic flow device to simultaneously transform up to 48 tissues into optically transparent structures, allowing subcellular imaging of nanomaterials more than 1 mm deep into tissues which is 25-fold greater than current techniques. A key finding is that nanomaterials can be retained in the processed tissue by chemical cross-linking of surface adsorbed serum proteins to the tissue matrix, which enables nanomaterials to be imaged with respect to cells, blood vessels, and other structures. We developed a computational algorithm to analyze and quantitatively map nanomaterial distribution. This method can be universally applied to visualize the distribution and interactions of materials in whole tissues and animals including such applications as the imaging of nanomaterials, tissue engineered constructs, and biosensors within their intact biological environment.

Structural design and active control of modular tensegrity systems

Tensegrity systems are self stressed reticulate structures composed of a set of compressed struts assembled inside a continuum of tendons. This principle is at the origin of lightweight and transparent structures that can cover large spaces and be erected, in particular cases, by deployment. In this paper, we propose a general design and optimization procedure adapted to modular structures following this principle. An application is presented on the case of a curved deployable footbridge. Besides, as lightweight frames, these systems are subject to deformation and vibration issues when faced to varying actions such as climatic, human, or seismic loads. Active control is as solution that allows, using actuators integrated into the structure, to attenuate these effects. On the case of a real plane modular tensegrity grid, we present a specific methodology for the active damping of the first two modes and its experimental validation.

Interference laser processing

Abstract The most important component of quantum optics is laser interference. Interference patterns are formed by splitting a coherent beam into multiple beams and correlating them. This study introduces a variety of beam correlators and discusses their characteristics. Beam correlator basics such as interference region in terms of pulse width, group delay dispersion effects on pulse width, optical delay adjustment, and interference pattern simulation are explained. A discussion of the history of interference processing begins with the method in 1967 and continues through the advancement of shorter wavelengths and pulse widths. The recent techniques of solid-liquid-solid for 3D nanofabrication, duplicated structures with laser-induced periodic surface structure, processing inside transparent materials, and 2D and 3D periodic structures fabricated by photo-sensitization are also presented.

Anisotropy, band-to-band transitions, phonon modes, and oxidation properties of cobalt-oxide core-shell slanted columnar thin films

Highly ordered and spatially coherent cobalt slanted columnar thin films (SCTFs) were deposited by glancing angle deposition onto silicon substrates, and subsequently oxidized by annealing at 475 °C. Scanning electron microscopy, Raman scattering, generalized ellipsometry, and density functional theory investigations reveal shape-invariant transformation of the slanted nanocolumns from metallic to transparent metal-oxide core-shell structures with properties characteristic of spinel cobalt oxide. We find passivation of Co-SCTFs yielding Co-Al2O3 core-shell structures produced by conformal deposition of a few nanometers of alumina using atomic layer deposition fully prevents cobalt oxidation in ambient and from annealing up to 475 °C.

Studying Cell Dynamics using Quantitative Phase Imaging

Most living cells do not absorb or scatter light significantly, i.e. they are essentially transparent, or phase objects. Phase contrast microscopy proposed by Zernike in the 1930's represents a major advance in intrinsic contrast imaging, as it reveals inner details of transparent structures without staining or tagging. While phase contrast is sensitive to minute optical path-length changes in the cell, down to the nanoscale, the information retrieved is only qualitative. Quantifying cell-induced shifts in the optical path-lengths permits nanometer scale measurements of structures and motions in a non-contact, non-invasive manner. Thus, quantitative phase imaging (QPI) has recently become an active field of study and various experimental approaches have been proposed.Recently, we have developed Spatial Light Interference microscopy (SLIM) as a highly sensitive QPI method. Due to its sub-nanometer pathlength sensitivity, SLIM enables interesting structure and dynamics studies over broad spatial (nanometers-centimeters) and temporal (milliseconds-weeks) scales. I will review our recent results on applying SLIM to basic cell studies, such as intracellular transport and cell growth. I will end with a discussion on new method, inspired from interferometry, for measuring cell-generated forces.

Synthesis and some surface studies of laminated ZnO/TiO2 transparent bilayer by two-step growth

A laminated bilayer was prepared by first depositing titanium dioxide (TiO2) nanocrystals on indium tin oxide (ITO) coated glass by a two-electrode cell. Zinc oxide (ZnO) thin film was thereafter deposited on the TiO2 by two different techniques: electrochemical deposition and vacuum evaporation. The films were characterized by some surface probing techniques. Morphological study revealed that particle size of the TiO2 underlayer increases between 110 and 138nm with increase in deposition voltage. It also showed that ZnO thin film (overlayer) completely covered the underlying TiO2 without chemical interaction between constituents of both layers. Cross-sectional FESEM study gave values of layered film thickness below 55µm. Exhibition of strong diffraction peak at plane (121) indicated preference of TiO2 film's growth orientation. It also suggested a feature of phase-pure brookite. Optical studies showed that each film exhibited strong absorption edge at λ=~330nm and transmitted fairly across visible light region. Energy band gap lied between 3.24 and 3.43eV. This study demonstrated successive layer deposition of transparent metal oxide structures from inorganic reagents. It also reaffirmed TiO2 as a recipe for barrier layer that can hinder transition of holes from absorber to transparent front contact of nanostructured photonic devices.

Interfacial RAFT polymerization induced ultra low dielectric loss ceramic/cyanate ester composites

Surface initiated reversible addition–fragmentation chain transfer polymerization (RAFT) of glycidyl methacrylate (GMA) was conducted on ceramic particles (ZNT). Then the ZNT@PGMA particles were introduced into cyanate ester (CE) matrix to prepare the ultra low dielectric loss ZNT@PGMA/CE composites. The ZNT@PGMA particles can be well dispersed in the CE matrix, resulting in the improvement of glass transition temperature by 40 °C and the increase of storage modulus by 130% in comparison to that of pure CE resins. The introduction of ZNT@PGMA particles can obviously decrease dielectric loss value of the ceramic/CE composites by one order of magnitude, which possesses potential in wave transparent composites and structures.

Restoring Wooden Structural Elements and Transparent Structures: Protection and Rehabilitation of Bosnian-Herzegovinian Medieval Fortifications

A great number of medieval fortifications in Bosnia-Herzegovina is in a state of deterioration, lacking ceiling and roof structures, usually made of wood. Their components usually make part of other structures in open areas covered with weed and stand as useless rubble or are neglected due to there being legal restrictions on owners of the land to participate in their reconstruction. Numerous fortifications have disappeared, while some still hold remnants of the times past in their stone and mortar. The detritus blocks the access to the structures whose importance is thus also neglected.One of the first tension resistant materials used in construction was wood. Wood is an extremely anisotropic material. The tensile strength of wood fibres is suitable for dimensioning. From an economic point of view, it is disputable whether the ruined wooden structures should be reinforced. Since wood is rather light and easy to incorporate and manipulate with, it seems that the most convenient procedure would be the replacement of the structures as they are relatively easy to unload. The most common in building construction is the need for repair or strengthening of the existing roof structure elements.

Potential of Vegetation in Improving Indoor Thermal Comfort and Natural Ventilation

According to the EPBD (2010) whilst improving the thermal performance of buildings good or at least tolerable thermal comfort conditions must be provided. But better thermal insulation and more airtight buildings increase the risk of summer overheating which makes mechanical cooling inevitable. This idea has been verified by the tendency of the last decade, when people were willing to install and use more frequently air conditioning devices during the summer heatwaves – increasing their energy consumption and electricity bills at the same time. We cannot neglect the importance of studies triggering an efficient way to minimise the cooling load of residential buildings by obstructing solar radiation. The usage of plants in front of transparent surfaces of the façade can avoid indoor overheating. Deciduous plants obstruct buildings’ solar access so that the microclimate around the building is improved too. The use of Green Infrastructure in different levels of planning processes, which would provide sustainable solutions for urban management, is also prescribed in the EU Biodiversity Strategy 2020. Of course in order to investigate the actual effect of trees on indoor thermal comfort we should take into consideration a list of other factors: such as orientation the type and thermal properties of the windows / transparent structures used, and the thermal transmittance values and heat storage capacity of the building. If we have taken into consideration the mentioned factors during simulation we can prove the effectiveness of vegetation for each case. Simulations are made on the base of transparency measurements carried out during the summer of 2014. The shading efficiency of trees is a species-specific attribute because of the varying crown structure and leaf density. Our analyses aimed at the quantification of the transmissivity of characteristic individuals of three frequently planted species (Celtis occidentalis, Sophora japonica, Tilia cordata). The measured data were the amount of transmitted shortwave radiation, compared with a measurement point under unobstructed sunlight. In preliminary studies we have shown that depending on species – a tree in front of the façade can decrease the solar gain on internal horizontal surface up to ~18-30 per cents. As the tree obstructs the solar access of the wall and that of transparent surfaces, a difference in indoor comfort is to be observed too.

Transparent and Flexible Thin Film Electroluminescent Devices Using HiTUS Deposition and Laser Processing Fabrication

Highly transparent thin film electroluminescent structures offering excellent switch on characteristics, high luminance and large break-down voltages have been deposited onto glass and flexible polymeric materials with no substrate heating using high target utilization sputtering. Deposition of ZnS:Mn as the active light emitting layer and Y2O3, Al2O3, Ta2O5, and HfO2 as dielectric materials arranged in single and multiple layer configurations were investigated. Devices incorporating Al2O3, HfO2 quadruple layers demonstrate the highest attainable luminance at low threshold voltage. Single pulse excimer laser irradiation of the phosphor layer prior to deposition of the top dielectric layer enhanced the luminance of the devices. The devices fabricated on glass and polymeric substrates exhibited a maximum luminance of 500 and 450 cdm $^{-2}$ when driven at $270~{\mathrm{ V}}_{\mathrm{ RMS}} $ and $220~{\mathrm{ V}}_{\mathrm{ RMS}} $ , respectively, with a 1.0 kHz sine wave.

Wearable, wireless gas sensors using highly stretchable and transparent structures of nanowires and graphene.

Herein, we report the fabrication of a highly stretchable, transparent gas sensor based on silver nanowire-graphene hybrid nanostructures. Due to its superb mechanical and optical characteristics, the fabricated sensor demonstrates outstanding and stable performances even under extreme mechanical deformation (stable until 20% of strain). The integration of a Bluetooth system or an inductive antenna enables the wireless operation of the sensor. In addition, the mechanical robustness of the materials allows the device to be transferred onto various nonplanar substrates, including a watch, a bicycle light, and the leaves of live plants, thereby achieving next-generation sensing electronics for the 'Internet of Things' area.

Real-Time Intraoperative Optical Coherence Tomography Imaging Confirms Older Concepts About the Berger Space

Background: The presence of a space between the posterior capsule and the anterior vitreous was first reported in 1887, but difficulties inherent in examining this structure made it impossible to visualize this area in vivo until now. Estimation of the size of this space was considered to be impossible. Materials and Methods: We utilized an optical coherence tomography (OCT) system attached to the Zeiss Opmi Lumera 700/Rescan microscope (Zeiss Ltd., Jena, Germany) to provide real-time images of the Berger space, the anterior hyaloid and the ligament of Wieger. Results: Imaging in 3 patients provided beautiful, real-time OCT images of the Berger space and of the ligament of Wieger. In one highly myopic eye, there was even evidence of anterior vitreous detachment. Conclusion: Previously unseen transparent structures of the eye can now be imaged intraoperatively using real-time OCT. This new technology seems very promising in achieving a better understanding of the anterior vitreous interface, more specifically of the anterior hyaloid and its posterior capsule attachment by the ligament of Wieger. Changes in the anterior hyaloid and its capsular attachment may contribute to a better understanding of the posterior segment complications after cataract surgery.

Load Bearing Structures of Glass Single-Storey Buildings

Since the period of application curtain wall on skeleton buildings, small single–storey buildings are the great topic for architects. By various means architects have effort to create an impression of floating roof structure, or an illusion of levitating roof over the country. The effect of transparent space, overlapping interior and exterior, is possible to achieve by use of various structural schemes and materials of support structure. Nowadays single-storey transparent buildings are regarded as a phenomenon, which presents progress in architecture from the point of dematerialization of support structures and details of secondary transparent structures. Glass is in contemporary transparent curtain walls used not only as a material of the building skin, but also as the material of the support structure in various structural elements within hierarchy of the load bearing structure. Flat glass sheets forming the building skin could be within the suitable chosen shape of enclosed envelope also load bearing structure.

Water policy, trust and governance in the Murray-Darling Basin

ABSTRACTConcerns for river health in the Murray-Darling Basin (MDB) area and shifting priorities for water use have led to a significant process of water reform over the last decade. The MDB area, also known as the food bowl of Australia, produces much of the country's food and is home to a significant portion of the population. A long-term drought, historical over-allocation of water for irrigation and climate variability have led to mounting concerns about the long-term viability of the rivers. While the reform process has resulted in the Commonwealth government taking control of the rivers from the States, it has also been influenced by changes in governments and consequent shifts in water allocation priorities from a privileging of agriculture to a broader approach encompassing economic, environmental and social concerns. This had led to uncertainty for the people and communities in the Basin and some confusion between the various layers of governance structures. This paper presents the results of exploratory research conducted with key, high-level stakeholders involved in water reform to examine their perceptions of the evolving water policy process. Despite agreement amongst stakeholders that returning water to the environment to ensure river health is critical, our research reveals significant tensions between stakeholders concerning the evolving process, particularly centred on the potential social outcomes and fairness and equity. This suggests the need for more integrated and transparent governance structures, attention to levels of trust between partners and a common vision that incorporates environmental, economic and social goals.