185 research outputs found
Influence of geometries on the assembly of snowman-shaped Janus nanoparticles
The self-assembly of micro/nanoparticles into suprastructures is a promising way to develop reconfigurable materials and to gain insights into the fundamental question of how matter organizes itself. The geometry of particles, especially those deviating from perfectly spherical shapes, is of significant importance in colloidal assembly because it influences the particle "recognition", determines the particle packing, and ultimately dictates the formation of assembled suprastructures. In order to organize particles into desired structures, it is of vital importance to understand the relationship between the shape of the colloidal building blocks and the assembled suprastructures. This fundamental issue is an enduring topic in the assembly of molecular surfactants, but it remained elusive in colloidal assembly. To address this issue, we use snowman-shaped Janus nanoparticles (JNPs) as a model to systematically study the effect of colloidal geometries on their assembled suprastructures. Ten types of JNPs with identical chemical compositions but with different geometries were synthesized. Specifically, the synthesized JNPs differ in their lobe size ratios, phase separation degrees, and overall sizes. We show that by altering these parameters, both finite suprastructures, such as capsules with different curvatures, and nonfinite suprastructures, including free-standing single-layered or double-layered JNPs sheets, can be obtained via self-assembly. All these different types of suprastructures are constituted by highly oriented and hexagonally packed JNPs. These findings demonstrate the significance of geometries in colloidal assembly, such that slightly changing the building block geometries could result in a large variety of very different assembled structures, without altering the chemistry of the particles
Polarity reversal in homologous series of surfactant-free Janus nanoparticles : toward the next generation of amphiphiles
The ability to finely tune the amphiphilic balance of Janus nanoparticles (JNPs) could represent a step forward toward creating the next generation of solid-state amphiphiles with significant potential for applications. The inherent amphiphilicity of JNPs stemming from an intrinsic polarity contrast between two surface regions is well-acknowledged, but remained difficult to demonstrate experimentally in the absence of surfactants and stabilizers. We have designed two homologous series of surfactant-free polymeric JNPs starting from polystyrene (PS) seed nanoparticles (NPs) on which we grew Janus lobes of different sizes via seed polymerization and phase separation of the 3-(triethoxysilyl)propyl-methacrylate (3-TSPM) monomer. The two series differ only by the radical initiator used in the seed polymerization: polar ionic ammonium persulfate (APS) vs nonpolar oil-soluble 2,2'-azobis(2-methylpropionitrile) (AIBN). To compare the two series, we employed them in the emulsification of water with heptane or molten paraffin wax. A polarity reversal of the JNPs within AIBN-JNP series could be observed from the catastrophic and transitional emulsion phase inversions and occurred when the more polar lobe was larger than the nonpolar seed PS lobe. Furthermore, the AIBN-JNPs appeared to be amphiphilic and adopt preferred orientation within the monolayer at the oil/water interface. We therefore demonstrated that in the absence of surfactants the amphiphilicity of the JNPs depends not only on the relative size of the lobes, but also on the surface polarity contrast, which can be tuned by changing the nature of radical initiator
Implementing fault-tolerant non-Clifford gates using the [[8,3,2]] color code
Quantum computers promise to solve problems that are intractable for
classical computers, but qubits are vulnerable to many sources of error,
limiting the depth of the circuits that can be reliably executed on today's
quantum hardware. Quantum error correction has been proposed as a solution to
this problem, whereby quantum information is protected by encoding it into a
quantum error-correcting code. But protecting quantum information is not
enough, we must also process the information using logic gates that are robust
to faults that occur during their execution. One method for processing
information fault-tolerantly is to use quantum error-correcting codes that have
logical gates with a tensor product structure (transversal gates), making them
naturally fault-tolerant. Here, we test the performance of a code with such
transversal gates, the [[8,3,2]] color code, using trapped-ion and
superconducting hardware. We observe improved performance (compared to no
encoding) for encoded circuits implementing non-Clifford gates, a class of
gates that are essential for achieving universal quantum computing. In
particular, we find improved performance for an encoded circuit implementing
the control-control gate, a key gate in Shor's algorithm. Our results
illustrate the potential of using codes with transversal gates to implement
non-trivial algorithms on near-term quantum hardware.Comment: 7+5 pages, comments welcom
Modeling the interfacial energy of surfactant-free amphiphilic Janus nanoparticles from phase inversion in Pickering emulsions
Determining the interfacial energy of nanoparticles is very challenging via traditional methods that first require measuring the contact angle of several liquids of a sessile drop on pellets or capillary rise in powder beds. In this work, we propose an alternative way to model the interfacial energy of nanoparticles directly from emulsion phase inversion data in Pickering emulsions. This could establish itself as a universal and facile way to determine the polarity of nanoparticles relative to a series of standard particles without the need to measure contact angles. Pickering emulsions of several oils in water were generated with a series of snowman-like Janus nanoparticles (JNPs), whose polarity gradually increased with the size of the more polar lobe. Depending on the oil to water ratio and the JNPs lobe size, oil-in-water (o/w) or water-in-oil (w/o) Pickering emulsions were obtained and the affinity of the JNPs to either water or oil can be inferred from the evolution of the emulsion phase inversion curves with these parameters. We further demonstrate that by adopting a simple model for the work of adhesion of JNPs with the water and oil phases, one can quantitatively calculate the relative interfacial energy change of the JNPs with the liquid. In addition, a knowledge of the interfacial energy of nanoparticles is useful for employing these in suspension polymerization to create surface nanostructured materials. The o/w and w/o Pickering emulsions obtained from monomers, such as styrene, could be polymerized, resulting in colloidosomes or hollow-like materials. The hollow materials exhibited a rather high volume storage capacity for the aqueous phase for extended periods of time, which could be released upon microwaving, making them ideal for use in long-term storage applications of various water-soluble actives
RANK CORRELATIONS AT THE LEVEL OF SOIL MITES (ACARI: GAMASIDA; ORIBATIDA) FROM CENTRAL PARKS OF BUCHAREST CITY, ROMANIA
The study of soil mites (Acari: Gamasida; Oribatida) was done in three parks in Bucharest city, CiĆmigiu, Unirea and Izvor, achieved by transects situated in the lateral sides (near the roads, boulevards or street), or in the middle of these areas. From 72 identified species of mites, 54 were saprophages-detritophages (Oribatida) and 18 predators (Gamasida). In all the parks 22 common species were identified: 14 oribatids and 8 predators. Spearman rank correlations applied between the number of individuals of the species from each park showed an appropriate concordance (rank correlation = râ) between them in CiĆmigiu and Unirea parks (râ = 0.30; râ = 0.12), CiĆmigiu and Izvor parks (râ = 0.68), in Unirea and Izvor (râ = 0.19; râ = 0.05) and a non concordance between those from CiĆmigiu and Izvor parks (râ = - 0.21). Taking into account the correlations among the common decomposer species of the transects from the parks, an appropriate concordance in transects of CiĆmigiu and Unirea parks (from râ = 0.32 for T1-T3, to râ = 0.58 for T2-T3) and a non concordance in all transects from studied parks (from râ = - 0.80 for T1-T2 to râ = - 0.01 for T1-T3) have been recorded. The common predators species have recorded an appropriate concordance in Unirea (râ = 0.12 for T1-T3) and in Izvor (from râ = 0.12 for T1-T3, to râ = 0.51 for T2-T3). The frequency of the common species from these studied parks, which realized multiple possibilities of concordance and fewer possibilities of non concordance, led to the assumption that the soil-vegetation complex of the studied parks have similar characteristics and exercise a positive influence on the presence of the populations of these mites
Studies on the establishment of conservation technologies of tillage mechanization in grain maize crop, under soil specific conditions from N-E Romania
For establishing the best
conservation technologies of tillage
mechanization from NE Romania in grain
maize crop, six technology variants were
tested in the spring of year 2007. In each
technology variant, we have determined the
qualitative indices for every work
equipment and the energetic and
exploitation indices for each farm
equipment. After crop sowing, we have
determined for each variant, soil resistance
to penetration, mean weighted diameter of
soil structural elements and water stability
of these elements. At the same time, we
have determined the fuel consumption per
hectare, for mechanized tillage and sowing.
We have also found that when selecting the
mechanization technologies of soil tillage,
we should take into account the obtained
seed yields. After the analysis of the
obtained results, we have established the
best mechanization technologies that
ensured soil conservation conditions for
maize crop
Synthesis and electrical properties of fullerene-based molecular junctions on silicon substrate
We report the synthesis and the electrical properties of fullerene-based
molecular junctions on silicon substrate in which the highly \pi-conjugated
molecule C60 (\pi quantum well) is isolated from the electrodes by alkyl chains
(\sigma tunnel barriers). Initially, the Si/SiO2/\sigmaC60 architecture was
prepared either by sequential synthesis (3 different routes) or by direct
grafting of the presynthesized C60-\sigma-Si(OEt)3 molecule. We described the
chemical synthesis of these routes and the physico-chemical properties of the
molecular monolayers. Then, the second \sigma tunnel barrier was added on the
Si/SiO2/\sigma C60 junction by applying a hanging mercury drop electrode
thiolated with an alkanethiol monolayer. We compared the electronic transport
properties of the Si/SiO2/\sigma C60//Hg and Si/SiO2/\sigma C60//\sigmaHg
molecular junctions, and we demonstrated by transition voltage spectroscopy
that the fullerene LUMO - metal Fermi energy offset can be tailored from ~ 0.2
eV to ~ 1 eV by changing the length of the alkyl chain between the C60 core and
the Hg metal electrode (i. e. from direct C60//Hg contact to 14 carbon atoms
tunnel barrier).Comment: Single pdf file including: main text, figures, tables and supporting
information
High-Efficiency Photoelectrocatalytic Hydrogen Generation Enabled by Palladium Quantum Dots-Sensitized TiO 2
Immuno-metabolic profile of patients with psychotic disorders and metabolic syndrome. Results from the FACE-SZ cohort
Background: Metabolic syndrome (MetS) is a highly prevalent and harmful medical disorder often comorbid with psychosis where it can contribute to cardiovascular complications. As immune dysfunction is a key shared component of both MetS and schizophrenia (SZ), this study investigated the relationship between immune alterations and MetS in patients with SZ, whilst controlling the impact of confounding clinical characteristics including psychiatric symptoms and comorbidities, history of childhood maltreatment and psychotropic treatments. Method: A total of 310 patients meeting DSM-IV criteria for SZ or schizoaffective disorders (SZA), with or without MetS, were systematically assessed and included in the FondaMental Advanced Centers of Expertise for Schizophrenia (FACE-SZ) cohort. Detailed clinical characteristics of patients, including psychotic symptomatology, psychiatric comorbidities and history of childhood maltreatment were recorded and the serum levels of 18 cytokines were measured. A penalized regression method was performed to analyze associations between inflammation and MetS, whilst controlling for confounding factors. Results: Of the total sample, 25% of patients had MetS. Eight cytokines were above the lower limit of detection (LLOD) in more than 90% of the samples and retained in downstream analysis. Using a conservative Variable Inclusion Probability (VIP) of 75%, we found that elevated levels of interleukin (IL)-6, IL-7, IL-12/23 p40 and IL-16 and lower levels of tumor necrosis factor (TNF)-α were associated with MetS. As for clinical variables, age, sex, body mass index (BMI), diagnosis of SZ (not SZA), age at the first episode of psychosis (FEP), alcohol abuse, current tobacco smoking, and treatment with antidepressants and anxiolytics were all associated with MetS. Conclusion: We have identified five cytokines associated with MetS in SZ suggesting that patients with psychotic disorders and MetS are characterized by a specific âimmuno-metabolicâ profile. This may help to design tailored treatments for this subgroup of patients with both psychotic disorders and MetS, taking one more step towards precision medicine in psychiatry. © 2022 The AuthorsImmuno-GĂ©nĂ©tique, Inflammation, retro-Virus, Environnement : de l'Ă©tiopathogĂ©nie des troubles psychotiques aux modĂšles animauxRĂ©seau d'Innovation sur les Voies de Signalisation en Sciences de la Vi
Morphological Design and Synthesis of Nanoparticles
Nanoparticles are particles with dimensions measured in nanometers, and exist at a scale where the physical, chemical, and biological properties of materials can differ significantly from those at a larger scale [...
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