Mechanochemical synthesis of crystalline and amorphous digold(i) helicates exhibiting anion- and phase-switchable luminescence properties

For the first time, mechanochemical synthesis has been used for the preparation of crystalline and amorphous dinuclear gold(i) helicates, [Au2L2](X)2 (L = xantphos; X = CF3SO3, SCN, BF4 and PF6), that show anion- and phase-switchable luminescence properties. This solid-state approach provides strategies for developing switchable luminescent materials

Thermodynamic and Kinetic Stabilities of Al(III) Complexes with N2O3 Pentadentate Ligands

: Al(III) complexes have been recently investigated for their potential use in imaging with positron emission tomography (PET) by formation of ternary complexes with the radioisotope fluorine-18 (18F). Although the derivatives of 1,4,7-triazacyclononane-1,4,7-triacetic acid (NOTA) are the most applied chelators for [Al18F]2+ labelling and (pre)clinical PET imaging, non-macrocyclic, semi-rigid pentadentate chelators having two N- and three O-donor atoms such as RESCA1 and AMPDA-HB have been proposed with the aim to allow room temperature labelling of temperature-sensitive biomolecules. The paucity of stability data on Al(III) complexes used for PET imaging instigated a complete thermodynamic and kinetic solution study on Al(III) complexes with aminomethylpiperidine (AMP) derivatives AMPTA and AMPDA-HB and the comparison with a RESCA1-like chelator CD3A-Bn (trans-1,2-diaminocyclohexane-N-benzyl-N,N',N'-triacetic acid). The stability constant of [Al(AMPDA-HB)] is about four orders of magnitude higher than that of [Al(AMPTA)] and [Al(CD3A-Bn)], highlighting the greater affinity of phenolates with respect to acetate O-donors. On the other hand, the kinetic inertness of the complexes, determined by following the Cu2+-mediated transmetallation reactions in the 7.5-10.5 pH range, resulted in a spontaneous and hydroxide-assisted dissociation slightly faster for [Al(AMPTA)] than for the other two complexes (t1/2 = 4.5 h for [Al(AMPTA)], 12.4 h for [Al(AMPDA-HB)], and 24.1 h for [Al(CD3A-Bn)] at pH 7.4 and 25 °C). Finally, the [AlF]2+ ternary complexes were prepared and their stability in reconstituted human serum was determined by 19F NMR experiments

Stability of Ampelometric Characteristics of Vitis vinifera L. cv. ‘Syrah’ and ‘Sauvignon blanc’ Leaves: Impact of Within-vineyard Variability and Pruning Method/Bud Load

Historically, grapevine (Vitis vinifera L.) leaf characterisation has been a driving force in the identificationof cultivars. In this study, ampelometric (foliometric) analysis was done on leaf samples collected fromhand-pruned, mechanically pruned and minimally pruned ‘Sauvignon blanc’ and ‘Syrah’ vines to estimatethe impact of within-vineyard variability and a change in bud load on the stability of leaf properties.The results showed that within-vineyard variability of ampelometric characteristics was high within acultivar, irrespective of bud load. In terms of the O.I.V. coding system, zero to four class differences wereobserved between minimum and maximum values of each characteristic. The value of variability of eachcharacteristic was different between the three levels of bud load and the two cultivars. With respect to budload, the number of shoots per vine had a significant effect on the characteristics of the leaf laminae. Singleleaf area and lengths of veins changed significantly for both cultivars, irrespective of treatment, while anglebetween veins proved to be a stable characteristic. A large number of biometric data can be recorded on asingle leaf; the data measured on several leaves, however, are not necessarily unique for a specific cultivar.The leaf characteristics analysed in this study can be divided into two groups according to the response toa change in bud load, i.e. stable (angles between the veins, depths of sinuses) and variable (length of theveins, length of the petiole, single leaf area). The variable characteristics are not recommended to be usedin cultivar identification, unless the pruning method/bud load is known

Commercial window glass tested as possible high dose dosimeter. Electron and gamma irradiation

The use of commercial window glass as possible high dose routine dosimeter has been investigated. Glass samples have been irradiated with doses in the range of 1-50 kGy using 60Co γ source, 4 MeV and 12 MeV electron accelerators. The samples were given a post irradiation thermal treatment (150 oC for 20 min) in order to improve the post irradiation stability of the measured specific optical absorbance, since a rapid fading of the optical absorbance has been observed at room temperature immediately after irradiation. The optical absorbance measurements of the irradiated samples, kept in the dark and at room temperature, were carried on for several weeks. The samples submitted to heat treatment showed a decrease of about 10-15% of the specific optical absorbance that became much less pronounced after 10 days from the irradiation. The response of the window glass plates is energy and dose rate dependent. This study shows the feasibility of using commercial window glass as a routine dosimeter in a certain dose range after proper calibration in the irradiation plant where they are going to be used

Sparse Kneser graphs are Hamiltonian

For integers k≥1 and n≥2k+1, the Kneser graph K(n,k) is the graph whose vertices are the k-element subsets of {1,…,n} and whose edges connect pairs of subsets that are disjoint. The Kneser graphs of the form K(2k+1,k) are also known as the odd graphs. We settle an old problem due to Meredith, Lloyd, and Biggs from the 1970s, proving that for every k≥3, the odd graph K(2k+1,k) has a Hamilton cycle. This and a known conditional result due to Johnson imply that all Kneser graphs of the form K(2k+2a,k) with k≥3 and a≥0 have a Hamilton cycle. We also prove that K(2k+1,k) has at least 22k−6 distinct Hamilton cycles for k≥6. Our proofs are based on a reduction of the Hamiltonicity problem in the odd graph to the problem of finding a spanning tree in a suitably defined hypergraph on Dyck words

AAZTA-Like Ligands Bearing Phenolate Arms as Efficient Chelators for 68Ga Labelling in vitro and in vivo

: The introduction of a phenolate pendant arm in place of an acetate on AAZTA- and DATA-like ligands resulted in hepta- and hexadentate chelators able to form Ga(III) complexes with thermodynamic stability and kinetic inertness higher than that of other Ga(III) complexes based on the parent 6-amino-6-methylperhydro-1,4-diazepine scaffold. In particular, the heptadentate AAZ3A-endoHB with a phenolate arm on an endocyclic N-atom shows a logKGaL of 27.35 and a remarkable resistance to hydroxide coordination up to basic pH (pH>9). This behaviour allows to also improve the kinetic inertness of the complex showing a dissociation half-life (t1/2 ) at pH 7.4 of 76 h. Although also the hexadentate AAZ2A-exoHB chelator forms a stable (logKGaL =24.69) and inert (t1/2 =33 h at pH 7.4) Ga(III) complex, the 68 Ga labelling showed a better radiochemical yield with AAZ3A-endoHB, especially at room temperature. Thus, a bifunctional chelator of AAZ3A-endoHB was synthesized bearing an isothiocyanate group that was conjugated to the N-terminus of a c(RGD) peptide for integrin receptor targeting. Finally, the conjugate was successfully labelled with 68 Ga isotope, and the resulting radiotracer tested for its stability in human serum and then in vivo for targeting B16-F10 tumours with miniPET imaging

Photoluminescence Study of Eu-Species Incorporated In Lithium Tetraborate and Silica

Steady-state – excitation and emission – photoluminescence spectra of europium species incorporated in single crystal and glassy lithium tetraborate (LTB) and silica are reported. Kinetic features, decay curves of the emission and lifetime data were measured. Spectral characteristics were analyzed with the aim of distinguishing the oxidation state, site-symmetry and morphology of europium species in different solid-state host matrices.Досліджено спектри стаціонарної фотолюмінесценції (збудження та випромінювання) європію, інкорпорованого в монокристалічний і полікристалічний літій тетраборат та кремнезем. Приведено дані кінетичної фотолюмінесценції: криві загасання та час життя збудженого стану іонів європію в зразках. Проведено аналіз спектральних характеристик з метою визначення стану інкорпорованих іонів європію – окислювального та агрегатного, а також локальної симетрії в різних матрицях.Исследованы спектры стационарной фотолюминесценции (возбуждения и излучения) европия, инкорпорированного в монокристаллы и поликристаллы литий тетрабората и кремнезема. Приведены данные кинетической фотолюминесценции: кривые затухания и время жизни возбужденного состояния ионов европия в образцах. Проведен анализ полученных спектральных характеристик с целью определения состояния инкорпорированных ионов европия – окислительного и агрегатного, а также локальной симметрии в разных матрицах

Nanotechnology-Based Targeted Drug Delivery: An Emerging Tool to Overcome Tuberculosis

The appearance and rapid spread of drug resistant strains of tuberculosis (TB), one of the deadliest infectious diseases, pose a serious threat to public health and increase the need for shorter, less toxic, and more effective therapies. Developing new drugs is difficult and often associated with side effects, so nanotechnology has emerged as a tool to improve current treatments and to rescue drugs having elevated toxicity or poor solubility. Due to their size and surface chemistry, antimicrobial-loaded nanocarriers are avidly taken up by macrophages, the main cells hostingMycobacterium tuberculosis. Macrophages are continuously recruited to infected areas, they can transport drugs with them, making passive targeting a good strategy for TB treatment. Active targeting (decorating surface of nanocarriers with ligands specific to receptors displayed by macrophages) further increases local drug concentration, and thus treatment efficacy. Although in in vivo studies, nanocarriers are often administered intravenously in order to avoid inaccurate dosage in animals, translation to humans requires more convenient routes like pulmonary or oral administration. This report highlights the importance and progress of pulmonary administration, passive and active targeting strategies toward bacteria reservoirs to overcome the challenges in TB treatment