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71.
Dr. Anthony D'Aléo Dr. David Gachet Dr. Vasile Heresanu Dr. Michel Giorgi Prof. Frédéric Fages 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(40):12764-12772
This article describes a series of nine complexes of boron difluoride with 2′‐hydroxychacone derivatives. These dyes were synthesized very simply and exhibited intense NIR emission in the solid state. Complexation with boron was shown to impart very strong donor–acceptor character into the excited state of these dyes, which further shifted their emission towards the NIR region (up to 855 nm for dye 5 b , which contained the strongly donating triphenylamine group). Strikingly, these optical features were obtained for crystalline solids, which are characterized by high molecular order and tight packing, two features that are conventionally believed to be detrimental to luminescence in organic crystals. Remarkably, the emission of light from the π‐stacked molecules did not occur at the expense of the emission quantum yield. Indeed, in the case of pyrene‐containing dye 4 , for example, a fluorescence quantum yield of about 15 % with a fluorescence emission maximum at 755 nm were obtained in the solid state. Moreover, dye 3 a and acetonaphthone‐based compounds 1 b , 2 b , and 3 b showed no evidence of degradation as solutions in CH2Cl2 that contained EtOH. In particular, solutions of brightly fluorescent compound 3 a (brightness: ε×Φf=45 000 M ?1 cm?1) could be stored for long periods without any detectable changes in its optical properties. All together, these new dyes possess a set of very interesting properties that make them promising solid‐state NIR fluorophores for applications in materials science. 相似文献
72.
Permanent binary phase masks with planar surfaces and high tolerance to laser radiation are recorded in the volume of photo-thermo-refractive glass using the contact copying technique and binary amplitude master masks. Conversion of a Gaussian beam to higher order modes is shown. 相似文献
73.
74.
We estimate multiplicative character sums over the integers with a fixed sum of binary digits and apply these results to study the distribution of products of such integers in residues modulo a prime p. Such products have recently appeared in some cryptographic algorithms, thus our results give some quantitative assurances of their pseudorandomness which is crucial for the security of these algorithms. 相似文献
75.
Marin Borcut Vasile Berinde 《Applied mathematics and computation》2012,218(10):5929-5936
In this paper we introduce the concept of a tripled coincidence point for a pair of nonlinear contractive mappings F : X3 → X and g : X → X. The obtained results extend recent coincidence theorems due to ?iri? and Lakshmikantham [V. Lakshmikantham, L. ?iri?, L., Coupled fixed point theorems for nonlinear contractions in partially ordered metric spaces, Nonlinear Anal. 70 (2009) 4341-4349]. 相似文献
76.
New Chemotypes for the Inhibition of (p)ppGpp Synthesis in the Quest for New Antimicrobial Compounds
Crescenzo Coppa Luca Sorrentino Monica Civera Marco Minneci Francesca Vasile Sara Sattin 《Molecules (Basel, Switzerland)》2022,27(10)
Antimicrobial resistance (AMR) poses a serious threat to our society from both the medical and economic point of view, while the antibiotic discovery pipeline has been dwindling over the last decades. Targeting non-essential bacterial pathways, such as those leading to antibiotic persistence, a bacterial bet-hedging strategy, will lead to new molecular entities displaying low selective pressure, thereby reducing the insurgence of AMR. Here, we describe a way to target (p)ppGpp (guanosine tetra- or penta-phosphate) signaling, a non-essential pathway involved in the formation of persisters, with a structure-based approach. A superfamily of enzymes called RSH (RelA/SpoT Homolog) regulates the intracellular levels of this alarmone. We virtually screened several fragment libraries against the (p)ppGpp synthetase domain of our RSH chosen model RelSeq, selected three main chemotypes, and measured their interaction with RelSeq by thermal shift assay and STD-NMR. Most of the tested fragments are selective for the synthetase domain, allowing us to select the aminobenzoic acid scaffold as a hit for lead development. 相似文献
77.
George-Theodor Stiubianu Adrian Bele Alexandra Bargan Violeta Otilia Potolinca Mihai Asandulesa Codrin Tugui Vasile Tiron Corneliu Hamciuc Mihaela Dascalu Maria Cazacu 《Molecules (Basel, Switzerland)》2022,27(23)
Silicone elastomer composites with piezoelectric properties, conferred by incorporated polyimide copolymers, with pressure sensors similar to human skin and kinetic energy harvester capabilities, were developed as thin film (<100 micron thick) layered architecture. They are based on polymer materials which can be produced in industrial amounts and are scalable for large areas (m2). The piezoelectric properties of the tested materials were determined using a dynamic mode of piezoelectric force microscopy. These composite materials bring together polydimethylsiloxane polymers with customized poly(siloxane-imide) copolymers (2–20 wt% relative to siloxanes), with siloxane segments inserted into the structure to ensure the compatibility of the components. The morphology of the materials as free-standing films was studied by SEM and AFM, revealing separated phases for higher polyimide concentration (10, 20 wt%). The composites show dielectric behavior with a low loss (<10−1) and a relative permittivity superior (3–4) to pure siloxane within a 0.1–106 Hz range. The composite in the form of a thin film can generate up to 750 mV under contact with a 30 g steel ball dropped from 10 cm high. This capability to convert a pressure signal into a direct current for the tested device has potential for applications in self-powered sensors and kinetic energy-harvesting applications. Furthermore, the materials preserve the known electromechanical properties of pure polysiloxane, with lateral strain actuation values of up to 6.2% at 28.9 V/μm. 相似文献
78.
Georgiana Dolete Bogdan Purcreanu Dan Eduard Mihaiescu Denisa Ficai Ovidiu-Cristian Oprea Alexandra Ctlina Bîrc Cristina Chircov Bogdan tefan Vasile Gabriel Vasilievici Anton Ficai Ecaterina Andronescu 《Molecules (Basel, Switzerland)》2022,27(17)
Since its first use as a drug delivery system, mesoporous silica has proven to be a surprisingly efficient vehicle due to its porous structure. Unfortunately, most synthesis methods are based on using large amounts of surfactants, which are then removed by solvent extraction or heat treatment, leading to an undesired environmental impact because of the generated by-products. Hence, in the present study, we followed the synthesis of a silica material with a wormhole-like pore arrangement, using two FDA-approved substances as templates, namely Tween-20 and starch. As far as we know, it is the first study using the Tween-20/starch combo as a template for mesoporous silica synthesis. Furthermore, we investigated whether the obtained material using this novel synthesis had any potential in using it as a DDS. The material was further analyzed by XRD, TEM, FT-IR, N2 adsorption/desorption, and DLS to investigate its physicochemical features. Vancomycin was selected as the active molecule based on the extensive research engaged towards improving its bioavailability for oral delivery. The drug was loaded onto the material by using three different approaches, assuming its full retention in the final system. Thermal analysis confirmed the successful loading of vancomycin by all means, and pore volume significantly decreased upon loading, especially in the case of the vacuum-assisted method. All methods showed a slower release rate compared to the same amount of the pure drug. Loadings by physical mixing and solvent evaporation released the whole amount of the drug in 140 min, and the material loaded by the vacuum-assisted method released only 68.2% over the same period of time, leading us to conclude that vancomycin was adsorbed deeper inside the pores. The kinetic release of the three systems followed the Higuchi model for the samples loaded by physical mixing and vacuum-assisted procedures, while the solvent evaporation loading method was in compliance with the first-order model. 相似文献
79.
Sergiu Shova Vasile Tiron Angelica Vlad Ghenadie Novitchi Dan G. Dumitrescu Madalin Damoc Mirela-Fernanda Zaltariov Maria Cazacu 《应用有机金属化学》2020,34(12):e5957
A di-manganese(III) complex structure was built by an original approach consisting of a two-step procedure. First, the mononuclear complex of the manganese(III) with the Schiff base of the salen-type ligand (H2L) derived from 1,3-bis(3-aminopropyl)tetramethyldisiloxane and 3,5-di-tert-butyl-2-hydroxybenzaldehyde was prepared. The main feature of note is the 12-membered chelate ring formed upon coordination of the Schiff base to central atom, which adopts a distorted N2O4 octahedron environment. In the second step, the acetato co-ligand in this complex is replaced by the carboxylate anion of a dicarboxilic acid, namely adipic acid. This metathesis reaction leads to the formation of dinuclear structure by connecting two manganese centers. The structure, as was determined by X-ray single crystal diffractometry, elemental and spectral analysis, is permethylated dinuclear complex with long aliphatic bridge. Thermal and magnetic properties were studied. In addition, the formation of magnetically induced stripe-ordered domains was highlighted by the magnetic force microscopy (MFM) on films born from diluted solution. 相似文献
80.
Dr. Dulce M. Morales Dr. Stefan Barwe Dr. Eugeniu Vasile Prof. Dr. Corina Andronescu Prof. Dr. Wolfgang Schuhmann 《Chemphyschem》2019,20(22):3030-3036
Earth-abundant transition-metal-based catalysts are attractive for alkaline water electrolysis. However, their catalytic properties are often limited by their poor electrical conductivity. Here, we present a strategy for enhancing the electrical conductivity of NiFe layered double hydroxide (LDH) in order to further improve its properties as an electrocatalyst for the oxygen evolution reaction (OER) in alkaline media. We show that NiFe LDH containing metal tetrasulfonate phthalocyanine in the interlayers between the NiFe oxide galleries can be coupled with graphene during liquid-phase exfoliation by taking advantage of their π-π stacking capabilities. A substantial enhancement in the electrocatalytic activity of NiFe LDH with respect to the OER was observed. Moreover, the activity and selectivity of the catalyst materials towards the oxygen reduction reaction were investigated, demonstrating that both the metal hydroxide layer and the interlayer species contribute to the electrocatalytic performance of the composite material. 相似文献