The reaction between TiCl4 and benzyl alcohol is a simple and nonaqueous procedure for the synthesis of highly crystalline titania nanoparticles at temperatures as low as 40 °C. XRD measurements ...prove the exclusive presence of the anatase phase. The particle growth depends strongly on temperature so that with the appropriate thermal conditions the particle size can be selectively adjusted in the range of 4−8 nm. Fine-tuning of the particle size is possible by a proper choice of the relative amounts of benzyl alcohol and titanium tetrachloride. Lowering the titanium tetrachloride concentration leads to a considerable decrease of particle size. BET measurements show particularly high surface areas, up to 345 m2/g for the smallest particles and 115 m2/g for the calcined material. TEM investigations reveal that the nanoparticles are nearly uniform in size and shape. The as-synthesized particles display only minor agglomeration, whereas the calcined material consists of completely nonagglomerated particles, with diameters ranging from 13 to 20 nm. The smallest particles are soluble in a THF/trioctylphosphine mixture that luminesces (425 nm) upon UV irradiation.
Abstract Parkinson’s disease is increasingly prevalent. It progresses from the pre-motor stage (characterised by non-motor symptoms like REM sleep behaviour disorder), to the disabling motor stage. ...We need objective biomarkers for early/pre-motor disease stages to be able to intervene and slow the underlying neurodegenerative process. Here, we validate a targeted multiplexed mass spectrometry assay for blood samples from recently diagnosed motor Parkinson’s patients ( n = 99), pre-motor individuals with isolated REM sleep behaviour disorder (two cohorts: n = 18 and n = 54 longitudinally), and healthy controls ( n = 36). Our machine-learning model accurately identifies all Parkinson patients and classifies 79% of the pre-motor individuals up to 7 years before motor onset by analysing the expression of eight proteins—Granulin precursor, Mannan-binding-lectin-serine-peptidase-2, Endoplasmatic-reticulum-chaperone-BiP, Prostaglaindin-H2-D-isomaerase, Interceullular-adhesion-molecule-1, Complement C3, Dickkopf-WNT-signalling pathway-inhibitor-3, and Plasma-protease-C1-inhibitor. Many of these biomarkers correlate with symptom severity. This specific blood panel indicates molecular events in early stages and could help identify at-risk participants for clinical trials aimed at slowing/preventing motor Parkinson’s disease.
The spontaneous emission decay dynamics of nanocrystal quantum dots embedded into biotemplated titania photonic crystals with a diamond-based lattice are investigated. Modification of the decay rate ...of quantum dot emission over wide frequency bandwidths in the visible by the photonic crystals is observed. Frequency-dependent analysis reveals both inhibition and enhancement of emission with a radiative lifetime variation by more than a factor of 10.
The reaction of transition metal chlorides with benzyl alcohol leads at low temperatures to oxidic nanostructures with low-dimensional particle shapes such as nearly spherical titania anatase ...nanoparticles, vanadium oxide nanorods, and tungsten oxide nanoplatelets. The process is simple, allows a scale-up in gram quantities, and leads to highly crystalline materials. Ethanol solutions containing tungsten oxide nanoparticles exhibit blue luminescence upon UV irradiation at room temperature.
The unique properties of colloidal semiconductor nanocrystals, or quantum dots, have attracted enormous interest in a wide range of applications, including energy, lighting, and biomedical fields. ...However, widespread implementation is hampered by the difficulty of developing large-scale and inexpensive synthesis routes, mainly due to our limited knowledge of formation reaction parameters. We report here a simple yet powerful method to experimentally determine critically important reaction parameters such as rate constants, activation barriers, equilibrium constants and reaction enthalpies. This method was applied to wurtzite cadmium selenide nanocrystals, yielding activation energies for growth and dissolution of 14 ± 6 kJ mol–1 and 27 ± 8 kJ mol–1, respectively, and a reaction enthalpy for nanocrystal growth of −15 ± 7 kJ mol–1. Moreover, the Gibbs free energy for growth was found to be negative at low temperatures, whereas dissolution becomes the spontaneous process above 150 °C.
Although Dementia with Lewy bodies (DLB) is the second most common form of dementia in elderly patients, it remains underdiagnosed compared with Alzheimer's (AD) and Parkinson's diseases (PD). This ...may be explained by overlapping clinical symptoms, e.g. Parkinsonism. While current MRI research focuses primarily on atrophy patterns of the frontal and temporal lobes, we focus on brainstem characteristics of DLB. In particular, we focused on brainstem atrophy patterns distinguishing DLB from Progressive Supranuclear Palsy (PSP) and PD based as the most common differential diagnoses.
We identified patients diagnosed with DLB, PD, PSP, and a control group (CTRL) in our psychiatric and neurological archives. All patients with competing diagnoses and without a high-quality T1 MPRAGE 3D dataset were excluded. We assessed atrophy patterns in all patients (1) manually and (2) using FastSurfer's segmentation algorithm in combination with FreeSurfer's brainstem volumetric calculations. We compared classical measurement methods and ratios with automated volumetric approaches.
One hundred two patients were enrolled and evaluated in this study. Patients with DLB (n = 37) showed on average less atrophy of the brainstem than patients with PSP (n = 21), but a significantly more pronounced atrophy than patients with PD (n = 36) and the control group (CTRL, n = 8). The mean measured sagittal diameters of the midbrain were 8.17 ± 1.06 mm (mean ± standard deviation) for PSP, 9.45 ± 0.95 mm for DLB, 10.37 ± 0.99 mm for PD and 10.74 ± 0.70 for CTRL. The mean measured areas of the midbrain were 81 ± 18 mm
for PSP, 105 ± 17 mm
for DLB, 130 ± 26 mm
for PD and 135 ± 23 mm
for CTRL. The mean segmented volumes of the midbrain were 5595 ± 680 mm
for PSP, 6051 ± 566 mm
for DLB, 6646 ± 802 mm
for PD and 6882 ± 844 mm
for CTRL. The calculated midbrain pons ratios did not show superiority over the absolute measurements of the midbrain for distinguishing PSP from DLB. Because of the relatively uniform atrophy throughout the brainstem, the ratios were not suitable for distinguishing DLB from PD.
DLB patients exhibit homogenous atrophy of the brainstem and can be distinguished from patients with PSP and PD by both manual measurement methods and automated volume segmentation using absolute values or ratios.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
A versatile and rapid sol–gel technique for the fabrication of high quality one-dimensional photonic bandgap materials was developed. Silica/titania multilayer materials are fabricated by a sol–gel ...chemistry route combined with dip-coating onto planar or curved substrates. A shock-cooling step immediately following the thin-film heat-treatment process is introduced. This step was found crucial in the prevention of film crack formationespecially in silica/titania alternating stack materials with a high number of layers. The versatility of this sol–gel method is demonstrated by the fabrication of various Bragg stack-type materials with fine-tuned optical properties by tailoring the number and sequence of alternating layers, the film thickness and the effective refractive index of the deposited thin films. Measured optical properties show good agreement with theoretical simulations, confirming the high quality of these sol–gel fabricated optical materials.
Crack-free thin-film stacks of silica and titania layers were prepared by a sol–gel dip-coating process involving flash-heating and shock-cooling steps. The final Bragg stacks were thermally annealed ...at different temperatures and their properties were investigated. While annealing increased the intra-layer properties (layer densification, increased crystallinity), it weakened inter-layer strength, leading to cracking and delamination under high-power laser irradiation. In contrast, stacks that were flash-heated only showed excellent radiation stability.
•High-quality titania–silica thin-film stacks were fabricated by sol–gel chemistry.•Effect of annealing on sample stability was investigated.•Annealing increases intra-layer stability but decreases inter-layer stability.•Flash-heated Bragg stacks (no annealing) display the highest radiation stability.
We developed a simple sol−gel chemistry-based opal infiltration method for the fabrication of high-quality planar titania photonic crystals. Polystyrene synthetic opals were infiltrated with a ...hydrophobic and air/moisture-stable liquid titania precursor. The high stability and hydrophobicity of the titania precursor enabled a new “lift-off/turn-over” backfilling technique that after calcination gives planar titania inverse opals with a flat and completely open surface, without the need for additional processing steps to remove any excess surface coating of the backfilling material. We also compare two different infiltration strategies and their influence on the structural and photonic properties. The obtained inverse opals display excellent photonic properties as evidenced by the presence of first-, second-, and third-order Bragg reflection peaks in accordance with theoretical photonic band structure calculations.
Nature has had millions of years to optimize photonic crystals - an endeavour mankind only really began in the 1980s. Often, we attempt to mimic and expand upon nature's designs in creating photonic ...structures that meet our technology-driven needs. While this strategy can be fruitful in fabricating novel architectures, one has to keep in mind that nature designed and optimized these structures for specific applications (e.g., colouration, camouflaging, signalling), but certainly not for use in photonic chips and optical circuits. To take full advantage of biological structures as blueprints for nanotechnology, it is important to understand the purpose and development of natural structural colours. In this review, we will discuss important aspects of the design, formation and evolution of the structures embedded in beetle exoskeletons that are responsible for their striking colouration. In particular, we will focus on the purpose of structural colours for camouflaging, mimicry and signalling. We will discuss their evolutionary and ecological development and compare the development of beetles with and without structural colours. Examples of non-colour-related structural functionalities will also be introduced and briefly discussed. Finally, a brief overview of nature's synthesis strategies for these highly evolved structures will be given, with particular focus on membrane assembly.
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