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Dynamic control of circular polarization in chiral metasurfaces is being used in many photonic applications. However, simple fabrication routes to create chiral materials with considerable and fully tunable chiroptical responses at visible and near-infrared wavelengths are scarce. Here, we describe a scalable bottom-up approach to construct cross-stacked nanoparticle chain arrays that have a circular dichroism of up to 11°. Due to their layered design, the strong superchiral fields of the inter-layer region are accessible to chiral analytes, resulting in a tenfold enhanced sensitivity in a chiral sensing proof-of-concept experiment. In situ restacking and local mechanical compression enables full control over the entire set of circular dichroism characteristics, namely sign, magnitude and spectral position. Strain-induced reconfiguration opens up an intriguing route towards actively controlled pixel arrays using local deformation, which fosters continuous polarization engineering and multi-channel detection. Stacked elastomeric arrays containing plasmonic nanoparticles show efficient chiral responses that can be fully controlled by mechanical compression and stack rotation. These simple layered materials may be useful modulators for photonic applications.

[Image: see text] For many photonic applications, it is important to confine light of a specific wavelength at a certain volume of interest at low losses. So far, it is only possible to use the polarized light perpendicular to the solid grid lines to excite waveguide–plasmon polaritons in a waveguide-supported hybrid structure. In our work, we use a plasmonic grating fabricated by colloidal self-assembly and an ultrathin injection layer to guide the resonant modes selectively. We use gold nanoparticles self-assembled in a linear template on a titanium dioxide (TiO(2)) layer to study the dispersion relation with conventional ultraviolet–visible–near-infrared spectroscopic methods. Supported with finite-difference in time-domain simulations, we identify the optical band gaps as hybridized modes: plasmonic and photonic resonances. Compared to metallic grids, the observation range of hybridized guided modes can now be extended to modes along the nanoparticle chain lines. With future applications in energy conversion and optical filters employing these cost-efficient and upscalable directed self-assembly methods, we discuss also the application in refractive index sensing of the particle-based hybridized guided modes.

Alignment of nanoparticles to hierarchical periodic structures is an emerging field in the development of patterned surfaces. Common alignment methods are based on templates that guide particle self-assembly. These can be formed using lithographic methods offering an almost free choice of the motif, while being expensive and time-consuming for large-scale production. Alternatively, template formation by controlled wrinkling offers a low-cost formation, but often suffers from the formation of defect structures like line-defects and cracks. Here, we show a preparation technique for nanoparticle alignment substrates that is based on the inscription of holographic surface relief gratings with a periodic sinusoidal wave pattern on the surface of azobenzene films. As interference patterns are employed for structure formation, very uniform and defect-free gratings with tunable grating height and grating period can be prepared. These substrates were successfully replicated to poly(dimethyl siloxane) and the replicas used for the alignment of polystyrene latex particles. Accordingly produced substrates exhibiting gratings with a variation in grating height allow for efficient screening of nanoparticle alignment in a geometrical confinement in one single experiment. We anticipate our studies as a promising tool for the development of sensors, tunable gratings and metamaterials.

We report nondestructive measurements of the properties of two-component epoxy adhesives at terahertz wavelengths using a transmissive time-domain spectroscopy system. The results show that the different epoxies have measurably different THz properties, that the changes which occur during the curing process can be monitored by measurements of their refractive index and absorption at terahertz wavelengths, and that this technique is sensitive enough to record changes in the optical material parameters during the postcuring process.

We demonstrate a novel colloidal self-assembly approach toward obtaining mechanically tunable, cost-efficient, and low-loss plasmonic nanostructures that show pronounced optical anisotropy upon mechanical deformation. Soft lithography and template-assisted colloidal self-assembly are used to fabricate a stretchable periodic square lattice of gold nanoparticles on macroscopic areas. We stress the impact of particle size distribution on the resulting optical properties. To this end, lattices of narrowly distributed particles (∼2% standard deviation in diameter) are compared with those composed of polydisperse ones (∼14% standard deviation). The enhanced particle quality sharpens the collective surface lattice resonances by 40% to achieve a full width at half-maximum as low as 16 nm. This high optical quality approaches the theoretical limit for this system, as revealed by electromagnetic simulations. One hundred stretching cycles demonstrate a reversible transformation from a square to a rectangular lattice, accompanied by polarization-dependent optical properties. On the basis of these findings we envisage the potential applications as strain sensors and mechanically tunable filters.

The functional properties of nanoparticle thin films depend strongly on the arrangement of the nanoparticles within the material. In particular, anisotropic optoelectronic properties can be achieved through the aligned assembly of 1D nanomaterials such as silver nanowires (AgNWs). However, the control of the hierarchical organization of these nanoscale building blocks across multiple length scales and over large areas is still a challenge. Here, we show that the oriented deposition of AgNWs using grazing incidence spraying of the nano-object suspensions on a substrate comprising parallel surface wrinkles readily produces highly oriented monolayer thin films on macroscopic areas (>5 × 5 mm2). The use of textured substrates enhances the degree of ordering as compared to flat ones and increases the area over which AgNWs are oriented. The resulting microscopic linear arrangement of AgNWs evaluated by scanning electron microscopy (SEM) reflects in a pronounced macroscopic optical anisotropy measured by conventional polarized UV-vis-NIR spectroscopy. The enhanced ordering obtained when spraying is done in the same direction as the wrinkles makes this approach more robust against small rotational offsets during preparation. On the contrary, the templating effect of the wrinkle topography can even dominate the shear-driven alignment when spraying is performed perpendicular to the wrinkles: the concomitant but opposing influence of topographic confinement (alignment along the wrinkles) and of spray-induced shear forces (orientation along the spraying direction) lead to films in which the predominant orientation of AgNWs gradually changes from one direction to its perpendicular one over the same substrate in a single processing step. This demonstrates that exploiting the subtle balance between shear forces and substrate-nanowire interactions mediated by wrinkles offers a new way to control the self-assembly of nanoparticles into more complex patterns.

We report the first outdoor measurements for continuous in vivo leaf-water monitoring using THz spectroscopy. For this, we have developed a compact and portable THz quasi time-domain spectrometer which can be powered by a battery. We monitor the water status of a corn plant (Zea mays) and discuss the influence of the day-night variations of the outdoor temperature.

We report nondestructive measurements of the properties of two-component epoxy adhesives at THz wavelengths using a reflective time-domain spectroscopy system. We describe a simple method to determine the refractive index, layer thickness, and absorption coefficient using time-domain data applying a Fresnel-equation based approach. The results indicate that the adhesive’s curing process may be monitored using a simple parameter extraction technique based on time-domain measurements for systems featuring small bandwidth, showing good agreement with data obtained with from transmission measurements.

We demonstrate the large-scale organisation of anisotropic nanoparticles into linear assemblies displaying optical anisotropy on macroscopic areas. Monodisperse gold nanorods with a hydrophilic protein shell are arranged by dip-coating on wrinkled surfaces and subsequently transferred to indium tin oxide (ITO) substrates by capillary transfer printing. We elucidate how tuning the wrinkle amplitude enables us to precisely adjust the assembly morphology and fabricate single, double and triple nanorod lines. For the single lines, we quantify the order parameter of the assemblies as well as interparticle distances from scanning electron microscopy (SEM) images. We find an order parameter of 0.97 and a mean interparticle gap size of 7 nm. This combination of close to perfect uni-axial alignment and close-packing gives rise to pronounced macroscopic anisotropic optical properties due to strong plasmonic coupling. We characterise the optical response of the assemblies on ITO-coated glass via UV/vis/NIR spectroscopy and determine an optical order parameter of 0.91. The assemblies are thus plasmonic metamaterials, as their periodicity and building block sizes are well below the optical wavelength. The presented approach does not rely on lithographic patterning and provides access to functional materials, which could have applications in subwavelength waveguiding, photovoltaics, and for large-area metamaterial fabrication.

In this article we discuss the influence of temporal stability on the value obtained for dielectric properties of materials measured by terahertz time-domain spectroscopy with particular emphasis on attenuated total reflection. The stability of three different terahertz attenuated total reflection spectroscopy systems is carefully characterized. The formalism for the complex refractive index extraction is presented and the effect of delay errors is calculated numerically. We found that good thermal stability of the terahertz system helps to minimize delay fluctuations and therefore the uncertainty of the resulting complex refractive index.

BACKGROUND AND PURPOSE: Whether general anesthesia for neurothrombectomy in patients with ischemic stroke has a negative impact on clinical outcome is currently under discussion. We investigated the impact of early extubation and ventilation duration in a cohort that underwent thrombectomy under general anesthesia. MATERIALS AND METHODS: We analyzed 103 consecutive patients from a prospective stroke registry. They met the following criteria: CTA-proved large-vessel occlusion in the anterior circulation, ASPECTS above 6 on presenting cranial CT, revascularization by thrombectomy with the patient under general anesthesia within 6 hours after onset of symptoms, and available functional outcome (mRS) 90 days after onset. RESULTS: The mean ventilation time was 128.07 ± 265.51 hours (median, 18.5 hours; range, 1–1244.7 hours). Prolonged ventilation was associated with pneumonia during hospitalization and unfavorable functional outcome (mRS ≥3) and death at follow-up (Mann-Whitney U test; P ≤ .001). According to receiver operating characteristic analysis, a cutoff after 24 hours predicted unfavorable functional outcome with a sensitivity and specificity of 60% and 78%, respectively. Our results imply that delayed extubation was not associated with a less favorable clinical outcome compared with immediate extubation after the procedure. CONCLUSIONS: Short ventilation times are associated with a lower pneumonia rate and more favorable clinical outcome. Cautious interpretation of our data implies that whether patients are extubated immediately after the procedure is irrelevant for clinical outcome as long as ventilation does not exceed 24 hours.

We demonstrate how water status measurements on plants can be performed using terahertz quasi time domain spectroscopy (THz QTDS). Compared with conventional THz TDS, this approach enables much more cost-efficient measurement setups and thus brings the technology closer to it's application in the field. Exemplary data is obtained from examining the drought stress response of rye and soy.

We demonstrate real time monitoring of the curing of two-component epoxy adhesives at THz frequencies. Our method is based on THz time domain spectroscopy (TDS) in reflection geometry. We monitor the curing of two-component adhesive over ten hours and extract refractive index, absorption and thickness.

To study the use of brain parenchyma sonography (BPS) in discriminating between patients with corticobasal degeneration (CBD) and progressive supranuclear palsy (PSP).Thirteen patients with PSP and eight with CBD were studied with BPS according to a standardized protocol.Seven (88%) of the eight CBD patients showed marked hyperechogenicity of the substantia nigra (SN) but none of eleven PSP patients (Mann-Whitney U test, p0.001). This finding indicated CBD with a positive predictive value of 100%. Marked dilatation of the third ventricle (width10 mm) was found in 10 (83%) of 12 PSP patients, but in none of the CBD patients (p0.005). BPS measurements of ventricle widths closely matched MRI measurements (Pearson correlation, r = 0.90, p0.001). The presence of at least one of the BPS findings 1) marked SN hyperechogenicity and 2) third-ventricle width10 mm indicated CBD with a sensitivity of 100%, a specificity of 83%, and a positive predictive value of 80%. Other BPS findings such as echogenicity of lentiform and caudate nuclei and widths of the frontal horns did not discriminate between CBD and PSP. One PSP patient could not be assessed because of insufficient acoustic temporal bone windows.Substantia nigra hyperechogenicity, reported earlier as characteristic brain parenchyma sonography finding in idiopathic Parkinson disease, is also typical for corticobasal degeneration.

Es bestehen ausreichend wissenschaftliche Evidenzen dafur, dass Botulinumtoxin (BTX) bei Schmerzen im Rahmen von muskularen Hyperaktivitatszustanden, wie bei Dystonien und bei Spastizitat, therapeutisch wirksam ist. Bei myofaszialen Schmerzen und verwandten Erkrankungen steht der definitive Beleg fur eine analgetische Wirkung nach Kriterien der evidenzbasierten Medizin noch aus. Bei Fibromyalgie scheint keine sichere klinische Wirkung vorzuliegen. Zum jetzigen Zeitpunkt wird der Einsatz von BTX-Injektionen zur Behandlung von Muskelschmerzen im Wesentlichen auf Behandlungen im Rahmen von kontrollierten Studien konzentriert bleiben. Nach Abschluss von breit angelegten multizentrischen plazebokontrollierten Studien kann erwartet werden, dass zukunftig die Bedeutung von BTX in der Schmerztherapie zunehmen wird.

Botulinumtoxin (BTX) wird seit mehr als 20 Jahren erfolgreich bei Erkrankungen mit muskularen Hyperaktivitaten eingesetzt. In den letzten Jahren kam es zu einer deutlichen Ausweitung der Anwendung bei autonomen Erkrankungen und in der Schmerztherapie. Die analgetischen Wirkungen von BTX-Injektionen werden vor dem Hintergrund erheblicher Plazeboeffekte und teilweise methodischer Mangel der vorgelegten Studien kontrovers diskutiert. Weiterhin bestehen noch unzureichende Konzepte zur Schmerzphysiologie allgemein sowie zu den spezifischen analgetischen Wirkmechanismen von Botulinumtoxin. Neben der Schmerzreduktion durch die bekannte BTX-Wirkung an der neuromuskularen Endplatte werden weitere lokale schmerzreduzierende Mechanismen und Wirkungen an anderen synaptischen Systemen postuliert. Derzeit kann BTX zur Schmerztherapie bei Dystonien und Spastiksyndromen sowie bei Analfissuren und Achalasie empfohlen werden. Bei myofaszialen Schmerzen, Migrane, Kopfschmerzen vom Spannungstyp und anderen seltenen Kopfschmerzsyndromen wurde eine Schmerzreduktion durch BTX berichtet, aber der definitive Beleg nach Kriterien der evidenzbasierten Medizin steht noch aus. Bei Fibromyalgie scheint keine sichere klinische Wirkung vorzuliegen. Es ist zu erwarten, dass in Zukunft die Bedeutung von BTX in der Schmerztherapie zunehmen wird. Botulinum toxin (BTX) has been used for more than 20 years to treat various muscle hyperactivity syndromes. Over the past years its use has expanded into the treatment of autonomic disorders and pain. Analgesic effects of BTX have been discussed controversially due to substantial placebo effects and flaws of the study designs used. Additionally, pathophysiological concepts of pain as well as specific analgesic mechanisms of BTX remain largely unclear. Apart from a pain reduction through the well documented BTX effects at the neuromuscular endplate, additional analgesic mechanisms including other synaptic and local effects have been suggested. Currently, BTX can be recommended for pain treatment in dystonia and spasticity as well as in analfissures and achalasia. In myofascial pain syndromes, migraine, tension-type headache and other rare headache syndromes pain relief by BTX has been reported, but definite proof according to evidence based medicine criteria is still lacking. In fibromyalgia there seems to be no analgesic effect. The role of BTX in pain therapy is likely to increase in the future.

We present a fast and low-cost delay generator for terahertz (THz) waves that transfers a rotational motion of a transparent dielectric cube into an effective THz delay. The device is easily implemented in the THz beam path and allows for coherent sampling over 40 ps with a scan rate of hundreds of hertz. Furthermore, we show that our approach is particularly suitable for fast THz imaging.

A new class of drugs, borylated derivatives of ferrocenium compounds, which show a comparatively facile synthesis is investigated on their boron neutron capture accumulation. Investigations focused on the fast and effective testing of 12 ferrocene derivatives with tetracoordinated boron atoms, which should accumulate in rodent tumors. The macroscopic studies on time-dependent boron distributions and boron concentrations in mice were carried out by inductively coupled plasma-atomic emission spectrometry, inductively coupled plasma-mass spectrometry, and quantitative neutron capture radiography. The determination of boron concentrations after injection of 2b showed high boron contents in spleen, liver, kidneys, less in lung and muscle, and poor in integral blood, blood plasma, tumor, and brain. It is interesting to note that 2b penetrates the blood-brain barrier which may be advantageous in the treatment of astrocytomas and glioblastomas.

Fructose malabsorption is characterized by the inability to absorb fructose efficiently. As a consequence fructose reaches the colon where it is broken down by bacteria to short fatty acids, CO2 and H2. Bloating, cramps, osmotic diarrhea and other symptoms of irritable bowel syndrome are the consequences and can be seen in about 50% of fructose malabsorbers. We have previously shown that fructose malabsorption is associated with early signs of mental depression and low serum tryptophan concentrations. It was therefore of interest whether a fructose-reduced diet could not only improve gastrointestinal complaints but also depressive signs seen in fructose malabsorbers.Fifty-three adults (12 males, 41 females), who were identified as fructose malabsorbers according to their breath-H2 concentrations, filled out a Beck's depression inventory-questionnaire, and a questionnaire with arbitrary scales for measurement of meteorism, stool frequency and quality of life for a 4-week period before dietary intervention and 4 weeks after dietary change as for fructose- and sorbitol-reduced diet.Depression scores were reduced by 65.2% after 4 weeks of diet (P0.0001), and there was a significant reduction of meteorism (P0.0001) and stool frequency (P0.01). Improvement of signs of depression and of meteorism was more pronounced in females than in males.Fructose- and sorbitol-reduced diet in subjects with fructose malabsorption does not only reduce gastrointestinal symptoms but also improves mood and early signs of depression.

The multivariate bilinear calibration methods Principal Component Regression (PCR) and Partial Least Squares Regression (PLS) are investigated for their capability to correct interferences in ICP-MS analysis. A universally applicable method is developed by optimizing the parameters for experimental design, for data pretreatment by internal standardisation, scaling, and mean centering, for the determination of the optimal number of latent variables, and for variable selection. Validation is performed with an artificial test system containing a wide range of representative analytes and interferences.

Symbolic model checking has been used to formally verify safety and operability specifications on an industrial solids handling process. The fundamental principles behind symbolic model checking are presented along with techniques used to model process hardware, relay ladder logic control instructions, and human operating procedures for verification purposes. The computational resources required to check the example process are presented, and faults detected in this process through symbolic verification are documented.

We have developed a symbolic verification method for determining the safety and operability of chemical process sequential control systems. The number of test cases required to verify a system grows exponentially as the number of components of the system increases. This state explosion problem limits our previous automatic verification method (Moon et al., 1992, Moon, 1994) to testing small systems. To mitigate this problem, we have adopted the Symbolic Model Verifier (SMV) which was originally developed by McMillan to test VLSI circuits. The method uses Boolean formulas to represent sets and relations in order to avoid building an explicit state transition graph which occupies most of the computer memory consumed for the computation. Ordered Binary Decision Diagrams are employed to manipulate the formulas efficiently in the model checking process. As a result, the SMV can verify large alarm systems including 10121 reachable states. The input language of SMV also makes the modeling of chemical processing systems as easy and less error prone processes. The method is demonstrated and the performance of the verifier is studied in a series of multiple alarm designs.

We present a novel THz-TDS system used for the identification of defects in joint plastic. The system utilizes two delay lines, one long, for defect location and the other short, for imaging of the defect. Cross-sectional THz images that reveal defects (air gaps) are been confirmed using CT measurements.

We present terahertz lenses made of polymeric compounds which provide a better focusing capability and an increased functionality than state of the art lenses made of pure base polymers. This is achieved by employing mixtures between polypropylene and alumina as well as polypropylene and zinc sulfide which allows for a significant increase of the refractive index of the lens base material.

In this work we present a novel concept for fast and low-cost terahertz imaging. A fast and stable source for time delay is created by inserting a rotating piece of high-density polyethylene into the THz path of a terahertz time domain spectrometer [1]. We will present the specifications of a first implementation of this device as well as imaging examples.

We present a THz-TDS based inline monitoring system for quality control in the production of paper. The system provides accurate live data about the paper quality and thickness, and is directly connected to the production process control.

We present terahertz (THz) lenses made of highly refracting polymeric compounds which provide a better focusing performance and an increased functionality in comparison to conventional THz lenses. Using mixtures consisting of polypropylene (PP) and alumina as well as PP and zinc sulfide allows a significant increase of the refractive index while simultaneously keeping a low extinction and dispersion. With these new material combinations, lenses with an increased focusing capability are realized. This is evaluated by focal plane measurements using a fiber coupled THz time-domain spectrometer.

Twelve ultrafiltrates of two ground waters rich in humic substances (up to 97.8 mg CL−1) and in salinity (up to: cations 44.3 meq L−1, anions 44.9 meq L−1) were investigated with ICP-MS and with NAA in parallel. With both techniques 22 elements were analysed in a wide concentration range (mg/L to ng/L). Ultrafiltration at pore sizes from 1000 nm down to 1 nm lowers the humic colloid content as well as the concentration of the colloidborne polyvalent cations. Carbon interferences were studied in detail using artificially prepared model waters. The detection limits of ICP-MS in the ultrafiltrates (0.01 μg/L–10 μg/L) and in pure analyte solutions (5 ng/L–600 ng/L) are compared with those of NAA for pure water analysis (0.004 ng/L–50 ng/L).

We discuss the potential of terahertz time domain spectroscopy for analyzing the thickness and quality of plastic pipes. We show that a fiber coupled spectrometer ideally suits the industrials needs for roughness and accuracy. Using a numerical time domain algorithm to extract the pipes thickness allows even for analyzing signals weekly towering the noise floor.

We present a fiber-coupled cw THz system for fast and accurate imaging in the field of non-destructive testing. Fibercoupled THz antennas make this system flexible and robust. The time delay is not realized via an optical delay line but by moving the detector antenna along the optical axis (Z-Scan).

We present two fiber-coupled terahertz (THz) time-domain transceiver heads that are well suited for zero degree reflection measurements and allow for flexible handling. One consists of only one photoconductive switch that is capable of emitting and detecting at the same time and the other operates with two antennas and a beam splitter made from a polypropylene-titanium (PP-TiO 2 ) compound.

Radar cross section (RCS) measurements are widely employed for the target identification of objects such as aircraft. The RCS of large, complex geometries is usually determined in a well defined, scaled experimental setup. In such a setup, the measuring frequency equates the frequency of interest multiplied by the scaling factor of the model. For high scaling factors, frequencies well above 100 GHz result so that conventional microwave equipment reaches its technological limits. In this paper, we discuss the use of a fiber coupled terahertz time domain spectroscopy system for angle dependent RCS measurements. Several measurements on simple objects like metal plates with corresponding simulations are performed. We also investigate how angular misalignment and displacement of the scatterer effects the measurement results. Moreover, we discuss the influence of non planar incident wavefronts and compare experimentally obtained data to simulations using an enhanced physical optics model.

We present a terahertz quasi time domain spectroscopy (QTDS) system setup which is improved regarding cost and compactness. The diode laser is mounted directly onto the optical delay line, making the optical setup more compact. The system is operated using a Raspberry Pi and an additional sound card. This combination replaces the desktop/laptop computer, the lock-in-amplifier, the stage controller and the signal generator. We examined not only a commercially available stepper motor driven delay line, but also the repurposed internal mechanics from a DVD drive. We characterize the performance of the new system concept.

The analgesic effects of botulinum toxin (BTX) have been discussed controversially due to substantial placebo effects and flaws in the study designs used. Additionally, pathophysiological concepts of pain and the specific analgesic mechanisms of BTX remain largely unclear. Apart from pain reduction through the well-documented effects of BTX at the neuromuscular endplate, additional analgesic mechanisms, including other synaptic and local effects, have been suggested. Currently, BTX can be recommended for pain treatment in dystonia and spasticity. In myofascial pain syndromes, pain relief by BTX injections has been reported, but definite proof according to evidence-based medicinal criteria is still lacking. In fibromyalgia, there seems to be no analgesic effect. The role of BTX in pain therapy is likely to increase in the future.