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Abstract: In this work the synthesis and characterization of gold nanoparticles functionalized by a novel thiol-organometallic complex containing Pd(II) centers is presented. Pd(II) thiol, trans, trans-[dithiolate-dibis(tributylphosphine)dipalladium(II)-4,4′-diethynylbiphenyl] was synthesized and linked to Au nanoparticles by the chemical reduction of a metal salt precursor. The new hybrid made of organometallic Pd(II) thiol-gold nanoparticles, shows through a single S bridge a direct link between Pd(II) and Au nanoparticles. The size-control of the Au nanoparticles (diameter range 2–10 nm) was achieved by choosing the suitable AuCl4−/thiol molar ratio. The size, strain, shape, and crystalline structure of these functionalized nanoparticles were determined by a full-pattern X-ray powder diffraction analysis, high-resolution TEM, and X-ray photoelectron spectroscopy. Photoluminescence spectroscopy measurements of the hybrid system show emission peaks at 418 and 440 nm. The hybrid was exposed to gaseous NO x with the aim to evaluate the suitability for applications in sensor devices; XPS measurements permitted to ascertain and investigate the hybrid –gas interaction.

Zinc oxide (ZnO) is a largely investigated semiconducting nanomaterial for photocatalytic applications and is an excellent active layer candidate in photovoltaics. Among native defects, having a primary role in ZnO optoelectronic properties, the influence of nearly ubiquitous planar faults of wurtzite sequences in ultrasmall (≤5 nm) nanocrystals (NCs) remains poorly understood. Here, we present a thorough study of ZnO NCs prepared under morphological control of covalently grafted vinyltrimethoxysilane (VTMS) and exhibiting either narrowing or widening of the band gap upon NCs downsizing, depending on the NC growth rate. By using synchrotron X-ray total scattering data, atomistic models and the Debye Scattering Equation (DSE) method, complemented by spectroscopic (FTIR and UV–vis) investigations, we provide a comprehensive quantitative picture in which effects from planar defects are disentangled from those due to NC size, morphology, and lattice strain (here controlled by preferential binding of VTMS on the ZnO basal faces). When faults occur in high concentration (linear density up to 1.6 × 106cm–1), NCs exhibit optical band gap narrowing (3.27 eV vs 3.37 eV in bulk ZnO), whereas gap widening (3.52 eV) is observed at a lower density (0.8 × 106cm–1), at which quantum-size confinement effects prevail. Supported by photoluminescence and photodegradation experiments, surface defect passivation by VTMS, affecting visible emissions and photocatalytic properties of ZnO, is also discussed in relation to silane coating and fault-driven bandgap. This work sheds light on the complex interplay among planar defects, quantum size effect, and surface modifications in ultrasmall ZnO NCs and on the importance of advanced X-ray total scattering methods toward atomically precise control of defects in nanostructures.

Highly anisotropic colloidal CsPbBr3nanoplatelets (NPLs) represent an appealing class of colloidal quantum wells with enhanced light emissivity. Strong quantum confinement imposed by the small platelet thickness and atomic flatness gives rise to enhanced oscillator strength, higher exciton binding energy, and narrow emission linewidth. While discrete thicknesses manifest themselves in discrete bandgap energies, fine-tuning of the emission energy can be achieved by compositional modulations. Here we address one of the most debated aspects of perovskite nanoplatelets: their crystal structure. Starting with the direct imaging by high-resolution electron microscopy (providing a clue on the pseudocubic faceting of the NPLs), we focus the study on X-ray total scattering techniques, based on the Debye scattering equation (DSE) approach, to obtain better atomistic insight. The nanoplatelets are six-monolayers thick and exhibit an orthorhombic structure. A thorough structure–morphology characterization unveils a specific orientation of the axial and equatorial bromides of the PbBr6octahedra versus the NPLs thickness; we found that {010} and {101} planes of the orthorhombic CsPbBr3lattice (Pnmaspace group) correspond to the six facets of the NPL, with basal planes being of {101} type. The NPLs undergo a lattice relaxation in comparison to cuboidal CsPbBr3NCs; the major deformation is observed in the axial direction, which suggests a structural origin of the higher compliance along the baxis. The DSE-based analysis also supports a CsBr surface termination model, with half Cs sites and a half (or slightly more) Br sites vacant.

Realization of the tetragonal phase of Cs2CuCl4is possible using specific crystal growth conditions at a temperature below 281 K. This work deals with the comparison of the magnetic susceptibility and the magnetization of this new tetragonal compound with the magnetic behavior of tetragonal Cs2CuCl2.9Br1.1, Cs2CuCl2.5Br1.5, and Cs2CuCl2.2Br1.8and presents consistent results for such quasi 2-D antiferromagnets. Structural investigation at low temperature for Cs2CuCl2.2Br1.8shows no phase transition. The structure remains in the tetragonal symmetry I4/mmm. Furthermore, several magnetic reflections corresponding to the propagation vector k= (0, 0, 0) are observed for this tetragonal compound through neutron diffraction experiments below the magnetic phase transition at TN= 11.3 K confirming its antiferromagnetic nature.

The Coulomb phase is an idealized state of matter whose properties are determined by factors beyond conventional considerations of symmetry, including global topology, conservation laws and emergent order. Theoretically, Coulomb phases occur in ice-type systems such as water ice and spin ice; in dimer models; and in certain spin liquids. However, apart from ice-type systems, more general experimental examples are very scarce. Here we study the partly disordered material CsNiCrF6and show that this material is a multiple Coulomb phase with signature correlations in three degrees of freedom: charge configurations, atom displacements and spin configurations. We use neutron and X-ray scattering to separate these correlations and to determine the magnetic excitation spectrum. Our results show how the structural and magnetic properties of apparently disordered materials may inherit, and be dictated by, a hidden symmetry—the local gauge symmetry of an underlying Coulomb phase.

Surface chemistry and core defects are known to play a prominent role in governing the photophysical properties of nanocrystalline semiconductors. Nevertheless, investigating them in small nanocrystals remains a complex task. Here, by combining X-ray scattering techniques in the wide- and small-angle regions and using the Debye scattering equation (DSE) method of analysis, we unveil a high density of planar defects in oleate-terminated zincblende (ZB) CdSe colloidal quantum dots (QDs) and size-dependent faceting within a square-cuboid morphology. Atomistic models of faulted ZB nanocrystals, based on the probabilistic stacking of CdSe layers in cubic and hexagonal sequences, and data analysis point to the preferential location of faults near the center of nanocrystals. By finely modeling faulting and morphological effects on the X-ray scattering pattern, a relaxation of the Cd–Se bond distance parallel to the stacking direction, up to +3% (2.71 Å) with respect to the reference bulk value (2.63 Å), is detected, at the cubic/hexagonal transitions. The smallest nanocrystals show cubic {100} facets; {111} facets appear above 4 nm and progressively extend at larger sizes. These structural and morphological features likely vary depending on the synthesis conditions; nevertheless, since planar defects are nearly ubiquitous in CdSe QDs, the modeling approach here presented has a general validity. This work also points to the great potential of combining small- and wide-angle X-ray scattering and DSE-modeling techniques in gaining important knowledge on atomic-scale defects of semiconductor nanocrystals, underpinning the comprehension of the impact of structural defectiveness on the exciting properties of these QDs.

Lesinurad, a uric acid reabsorption inhibitor that received Food and Drug Administration approval in 2015, is known to crystallize in three unsolvated crystal forms and in a few solvated phases. The structures of the former have been determined by state-of-the-art powder diffraction methods, highlighting significant conformational as well as supramolecular differences, resulting in hydrogen bonded centrosymmetric dimers (Form 1) or helical chains (Form 2). In the complex crystal packing in Form 3, additional one-dimensional (1D) ribbons held together by unexpected C═O···Br interactions of the halogen-bond type are found. Thermal analyses and variable-temperature powder diffraction measurements (including high-temperature synchrotron X-ray diffraction experiments) provided evidence for the reversible formation of a new phase, Form 2hT, obtained upon heating above 100 °C powders of Form 2. Structure solution and refinement of the high-temperature phase made it possible to attribute the structural change to a 60° rotation of the cyclopropyl residue, leaving unaffected the conformation of the (longer) polar branch and the supramolecular 1D helical chain arrangement found in the RT phase.

The best treatment option for patients with type 2 diabetes in whom treatment with metformin alone fails to achieve adequate glycaemic control is debated. We aimed to compare the long-term effects of pioglitazone versus sulfonylureas, given in addition to metformin, on cardiovascular events in patients with type 2 diabetes.

Crystal defects in highy luminescent colloidal nanocrystals (NCs) of CsPbX3perovskites (X = Cl, Br, I) are investigated. Here, using X-ray total scattering techniques and the Debye scattering equation (DSE), we provide evidence that the local structure of these NCs always exhibits orthorhombic tilting of PbX6octahedra within locally ordered subdomains. These subdomains are hinged through a two-/three-dimensional (2D/3D) network of twin boundaries through which the coherent arrangement of the Pb ions throughout the whole NC is preserved. The density of these twin boundaries determines the size of the subdomains and results in an apparent higher-symmetry structure on average in the high-temperature modification. Dynamic cooperative rotations of PbX6octahedra are likely at work at the twin boundaries, causing the rearrangement of the 2D or 3D network, particularly effective in the pseudocubic phases. An orthorhombic, 3D γ-phase, isostructural to that of CsPbBr3is found here in as-synthesized CsPbI3NCs.

Microcrystalline vinpocetine, coground with cross-linked polyvinylpyrrolidone, affords hybrids containing nanosized drug nanocrystals, the size and size distributions of which depend on milling times and drug-to-polymer weight ratios. Using an innovative approach to microstructural characterization, we analyzed wide-angle X-ray total scattering data by the Debye function analysis and demonstrated the possibility to characterize pharmaceutical solid dispersions obtaining a reliable quantitative view of the physicochemical status of the drug dispersed in an amorphous carrier. The microstructural properties derived therefrom have been successfully employed in reconciling the enigmatic difference in behavior between in vitroand in vivosolubility tests performed on nanosized vinpocetine embedded in a polymeric matrix.

Size and shape tunability and low-cost solution processability make colloidal lead chalcogenide quantum dots (QDs) an emerging class of building blocks for innovative photovoltaic, thermoelectric and optoelectronic devices. Lead chalcogenide QDs are known to crystallize in the rock-salt structure, although with very different atomic order and stoichiometry in the core and surface regions; however, there exists no convincing prior identification of how extreme downsizing and surface-induced ligand effects influence structural distortion. Using forefront X-ray scattering techniques and density functional theory calculations, here we have identified that, at sizes below 8 nm, PbS and PbSe QDs undergo a lattice distortion with displacement of the Pb sublattice, driven by ligand-induced tensile strain. The resulting permanent electric dipoles may have implications on the oriented attachment of these QDs. Evidence is found for a Pb-deficient core and, in the as-synthesized QDs, for a rhombic dodecahedral shape with nonpolar {110} facets. On varying the nature of the surface ligands, differences in lattice strains are found.

Total Scattering Methods are nowadays widely used for the characterization of defective and nanosized materials. They commonly rely on highly accurate neutron and synchrotron diffraction data collected at dedicated beamlines. Here, we compare the results obtained on conventional laboratory equipment and synchrotron radiation when adopting the Debye Function Analysis method on a simple nanocrystalline material (a synthetic iron oxide with average particle size near to 10 nm). Such comparison, which includes the cubic lattice parameter, the sample stoichiometry and the microstructural (size-distribution) analyses, highlights the limitations, but also some strengthening points, of dealing with conventional powder diffraction data collections on nanocrystalline materials.

Ceria-based materials have many interesting applications including catalysis, fuel cells, and biology. The size- and shape-dependent changes in the catalytic properties of nanoceria are often attributed to stabilization Ce3+defects on the nanoparticle surface. In this paper, we have performed a systematic analysis of the structure of polyhedral CeO2nanoparticles of 2–10 nm, under ambient conditions, using a combination of transmission electron microscopy, X-ray diffraction, and X-ray spectroscopy at Ce K- and L-edges. We reveal that under ambient conditions Ce3+concentration does not depend on the size; however, the unit cell parameter and the pseudo Debye–Waller factors systematically change due to size-dependent surface contribution. The presence of Ce3+traces relates to the use of Ce3+precursors during synthesis. Exposure of nanoparticles to an intense beam of X-ray radiation causes reduction of Ce4+ions, the extent of which is size-dependent.

Come together!A combined real‐ and reciprocal‐space total scattering approach was realized by applying Debye and radial distribution functions to nanocrystalline and amorphous fractions within the same experimental pattern. The method allows for the quantitative description of microstructural features induced by the amorphous–crystalline interplay in silica–titania nanocomposites (see picture).

Eine kombinierte Röntgenbeugungmethodewurde entwickelt, die Debye‐ und radiale Verteilungsfunktionen auf nanokristalline und amorphe Fraktionen innerhalb des gleichen experimentellen Musters anwendet. Die Methode ermöglicht die quantitative Beschreibung mikrostruktureller Merkmale, die durch amorph‐kristalline Wechselwirkungen in Siliciumdioxid‐Titandioxid‐Nanokompositen hervorgerufen werden (siehe Bild).

AbstractThe main aberrations affecting data collected with 1D position sensitive detectors in Debye-Scherrer capillary geometry are examined, and analytical corrections proposed. The equations are implemented in two of the most advanced software based on the Rietveld and Whole Powder Pattern Modelling methods, respectively, for structure and microstructure analysis. Application to MYTHEN, a fast single photon counting detector developed at the Swiss Light Source, is discussed in detail.

To investigate whether repetitive transcranial magnetic stimulation (rTMS) can modify spasticity.

Abstract:: Magnetic circular dichroism (MCD) in X-ray absorption has been measured at the L 2, 3 edges of Fe in ex-situ grown Fe and Fe 0.50 Co 0.48 V 0.02 films by means of the transmission method. A new approach is developed for fitting the observed transmittance, which describes the resonance lineshapes as (generalized) Fano profiles. Analytical integration of each single resonance allows a more reliable determination of the orbital and spin magnetic moments based on the MCD sum rules. The results are consistent with an increase of the Fe spin and orbital magnetic moment in Fe-Co alloys as obtained by other experiments and band structure calculations.

Abstract:: The local structure of cobalt and nickel in single crystals of decagonal quasicrystals with composition Al71.5Ni15.5Co13 and Al75Ni14.5Co10.5 have been studied by polarized EXAFS. Significant differences between the Ni and Co local environments have been detected. The effective absence of the 4 Å periodicity along the decagonal axis in these QCs is confirmed and indications about its reasons are presented.

The n-dimensional atomic surfaces modelling technique has been applied to solve the basic decagonal phase of Al71Ni22Co7. This means describing the quasicrystal structure by means of a probability density in perpendicular space. The atomic surfaces are the supports of this probability function. n-dimensional atomic surfaces models were born as ideal structures. We extend the technique to deal with the several different disorder phenomena characterizing real structures.

The numerous phase transformations of quasicrystals observed can be separated into two distinct classes, the transitions from quasicrystals-to-quasicrystals and from quasicrystals-to-crystals of periodic approximants. The formation of modulated quasicrystals driven by chemical ordering represents a member of the first class. The transformation of a quasicrystal to orientationally twinned domain structures of approximants belongs to the latter class.

State-of-the-art X-ray diffraction techniques allow quasicrystals to be characterised quantitatively. Based on two-dimensional scans of Bragg reflections with high spatial resolution twinned approximants or nanodomain structures can be reliably distinguished from quasiperiodic average structures. Linear phason strain as well as mosaicity can directly be detected in situ under non-ambient conditions. Accurate cell parameters can be obtained. The experimental limitations are discussed.

Colloidal nanocrystals (NCs) of fully inorganic lead halide perovskites (LHPs) are the latest generation of quantum-dot materials with compelling optical characteristics. Favored by the nearly regular cubic shape of NCs, they readily self-organize into highly ordered supercrystals (SCs) that have been stimulating in-depth investigation of uncommon collective properties at the fundamental level. Herein, we explore LHP NC SCs formed in colloidal suspensions and as solid materials, without any prior rigorous NC size-selection process. The spontaneous self-organization manifests itself in synchrotron wide-angle X-ray total scattering (WAXTS) measurements of randomly oriented ensembles of SCs by virtue of the substructure in the 100Cpeak (in cubic notation). By developing atomistic models of SCs, we find an evidence that, in spite of the initial NCs size polydispersity (up to 20%), SCs of CsPbBr3and CsPbBr1.5I1.5NCs form through a size segregation process. The SCs exhibit high spatial structural coherence, that is, crystallographic alignment between NCs, along two and three directions, a degree of orientational order (the SCs mosaicity) below 2°, and coherent sizes on the order of tens of nanometers. In situcoupled photoluminescence (PL) and WAXTS experiments evidence pronounced electronic coupling between NCs in SCs, seen as an ca. 50–70 meV red-shifted emission in dried samples compared to the corresponding dilute solution of NCs.

With the object of proving whether seqeuntial or alternate forms of chemotherapy would be advantageous one over the other in treating advanced breast cancer and with the purpose of evaluating two different anthracyclines at equimolecular doses in the above-mentioned alternating regimens, 250 patients who had received no prior chemo- or hormonotherapy were entered in a prospective randomized trial. Group A was administered 4-epiadriamycin and cyclophosphamide for 8 courses, followed by 6 cycles of CMF, and medroxyprogesterone acetate (MPA) from the beginning of therapy until progression. In group B, adriamycin + cyclophosphamide were alternated with CMF every two courses until 14 cycles were completed. Group C received 4'-epiadriamycin + cyclophosphamide alternated with CMF for 14 courses. In groups B and C, MPA was administered as in group A. Two hundred and twenty-four patients were evaluated. CR+PR were observed in 55.8 % of group A, 43.4 % of group B, and 46.4 % of group C. Median duration of responses was 16 months (m) in group A, 13 m in group B and 20 m in group C., and median survival (CR + PR) was 16.5 m in group A, 16 m in group B and 24 m in group C. There were no statsitically significant differences among the three groups in terms of response rate, duration of response and survival; furthermore, toxicity was moderate in all groups. At equimolecular doses there were no differences between adriamycin and epirubicin in the alternating schedules.

The atomic surfaces (ASs), supports of a probability density in perpendicular space, are a powerful instrument for describing quasicrystal structure. The attainable resolution of diffraction data does not allow a direct ASs determination hence they need to be modeled and refined. A simple set of geometric rules can be found for modeling ASs. The ASs shapes are constrained by interatomic distances, density and symmetry of the physical 3D structure.

Summary This study was carried out to assess the efficacy of high-dose ifosfamide/mesna (HDIFM) in the treatment of advanced or recurrent cancer of the cervix. In all, 18/21 evaluable patients with advanced or inoperable cervical cancer were included. The mean age was 42 years (range, 31–58 years); and the International Federation of Gynecology and Obstetrics (FIGO) stage was III in 10 patients and IV in 11. The Karnofsky performance status ranged between 70 and 90, with a median of 77. Ten patients had previously been treated with surgery, radium and cobalt (8) or cobalt alone (2). Therapy consisted of 3.5 g/m2, ifosfamide (IFO) given in an 8-h i.v. infusion on days 1–5 and mesna at 20% of the IFO dose, given i.v. at 0, 2, 4, 6 and 8 h, followed by mesna at 40% of the IFO dose by the oral route at 10 and 12 h on days 1–5. For evaluation purposes, patients received at least two cycles. Toxicity was registered in 137 cycles and was mild to moderate. Three complete (16.6%) and six partial (33.3%) responses were observed (50%), but 66% of them occurred in areas that had not previously been irradiated. The median duration of response was 14 months and the overall median survival was 15+ months (18+ months for responders). The Karnofsky scale after treatment ranged from 90 to 100. The results of this study indicate that HDIFM is well tolerated, giving a high percentage of remission (50%) and significantly improving the quality of life.

Thirty patients with advanced squamous cell carcinoma of the cervix were included in a phase II study with cisplatin (DDP) and ifosfamide (IF)/mesna. They received a median of 4 courses of chemotherapy and were all evaluable for response and toxicity. Each cycle consisted of 2 500 mg/m2 IF i.v. days 1-5; mesna 500 mg/m2 i.v. at hours 0 and 2, and 1 000 mg/m2 per os at hours 6 and 10, days 1-5; DDP 20 mg/m2 i.v., days 1-5. Cycles were repeated every 4 weeks. One patient obtained CR and 14 PR giving an overall response rate of 50%. Mean duration of response was 21 months. Anemia grade 3 developed in 7 patients, leukopenia grade 3 in 9 patients and grade 4 in one patient; thrombopenia grade 3 in 2; creatinine clearance grade 3 in one; CNS grade 3 in one and cystitis grade 3 in one patient. Overall median survival time was about 25 + months (3-63 +); after a follow-up of 70 months, 11 patients (37%) are still alive with a median survival of 31 + months. IF plus DDP seems to be a good combination for treatment of advanced cervical cancer, with acceptable tolerance and response rate.