215 research outputs found

    Global symplectic coordinates on gradient Kaehler-Ricci solitons

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    A classical result of D. McDuff asserts that a simply-connected complete Kaehler manifold (M,g,ω)(M,g,\omega) with non positive sectional curvature admits global symplectic coordinates through a symplectomorphism Ψ:MR2n\Psi: M\rightarrow R^{2n} (where nn is the complex dimension of MM), satisfying the following property (proved by E. Ciriza): the image Ψ(T)\Psi (T) of any complex totally geodesic submanifold TMT\subset M through the point pp such that Ψ(p)=0\Psi(p)=0, is a complex linear subspace of CnR2nC^n \simeq R^{2n}. The aim of this paper is to exhibit, for all positive integers nn, examples of nn-dimensional complete Kaehler manifolds with non-negative sectional curvature globally symplectomorphic to R2nR^{2n} through a symplectomorphism satisfying Ciriza's property.Comment: 8 page

    Mechanochemistry for Healthcare: Revealing the Nitroso Derivatives Genesis in the Solid State

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    Nitroso derivatives with unique characteristics have been extensively studied in various fields, including biology and clinical research. Although there has been substantial investigation of “nitrosable” components in many drugs and commonly consumed nutrients, there is still a need for a higher awareness about their formation and characterization. This study demonstrates how these derivatives can be produced through a mechanochemical procedure under solid-state conditions. The results include synthesizing previously unknown compounds with potential biological and pharmaceutical applications, such as a nitrosamine derived from a Diclofenac-like structure

    Ammonia Synthesis by Mechanochemistry

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    The design and use of organic, inorganic, and metal-based catalysts is critical to academic and industrial laboratories all around the world. In this framework, ammonia production embodies the most iconic use of catalysis. This review aims to describe the most recent and exciting developments in the mechanocatalytic preparation of ammonia

    Tandem Baeyer–Villiger/Wittig/oxa-Michael addition: One-step to 5-substituted γ-lactones

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    The results reported in this study provide a practical protocol for the construction, in one single step of synthetically important γ-lactones in good yields starting from α-hydroxy cyclobutanone, H2O2 and several stabilized phosphonium ylides. Our synthetic strategy relies on a tandem Baeyer–Villiger oxidation/Wittig reaction/oxa-Michael addition

    Mechanochemistry Frees Thiourea Dioxide (TDO) from the ‘Veils’ of Solvent, Exposing All Its Reactivity

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    The synthesis of nitrogen-based heterocycles has always been considered essential in developing pharmaceuticals in medicine and agriculture. This explains why various synthetic approaches have been proposed in recent decades. However performing as methods, they often imply harsh conditions or the employment of toxic solvents and dangerous reagents. Mechanochemistry is undoubtedly one of the most promising technologies currently used for reducing any possible environmental impact, addressing the worldwide interest in counteracting environmental pollution. Following this line, we propose a new mechanochemical protocol for synthesizing various heterocyclic classes by exploiting thiourea dioxide (TDO)'s reducing proprieties and electrophilic nature. Simultaneously exploiting the low cost of a component of the textile industry such as TDO and all the advantages brought by a green technique such as mechanochemistry, we plot a route towards a more sustainable and eco-friendly methodology for preparing heterocyclic moieties

    Balanced metrics on Cartan and Cartan-Hartogs domains

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    This paper consists of two results dealing with balanced metrics (in S. Donaldson terminology) on nonconpact complex manifolds. In the first one we describe all balanced metrics on Cartan domains. In the second one we show that the only Cartan-Hartogs domain which admits a balanced metric is the complex hyperbolic space. By combining these results with those obtained in [13] (Kaehler-Einstein submanifolds of the infinite dimensional projective space, to appear in Mathematische Annalen) we also provide the first example of complete, Kaehler-Einstein and projectively induced metric g such that αg\alpha g is not balanced for all α>0\alpha >0.Comment: 11 page

    Development of sexual organs and fecundity in Octopus vulgaris Cuvier, 1797 from the Sardinian waters (Mediterranean Sea)

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    In this paper we report information about the sexual maturity process of 245 Octopus vulgaris specimens (75 females and 170 males) from the Mediterranean Sea. For both sexes, six stages of sexual maturity (immature, developing, maturing, mature, spawning, and spent) are identified on the basis of macroscopic and microscopic observations of the reproductive system and linked with some reproductive indices. A good correspondence between gonad appearance and its histological structure is observed, highlighting, in females, how oviducal gland morphology plays a crucial role in the macroscopic evaluation of maturity. The Gonadosomatic and Hayashi indices, in the two genders, and the Oviducal Gland index in females alone do not allow distinguishing all the stages in an irrefutable way. Data on the potential fecundity, oocyte and spermatophore size are reported and compared with literature. In addition, spermatophore components are also computed. The results reported in this paper lead to easy identification of the different phases of sexual maturation of O. vulgaris and could constitute an important tool for defining assessment models in view of sound management of this species

    Development of sexual organs and fecundity in Octopus vulgaris Cuvier, 1797 from the Sardinian waters (Mediterranean Sea)

    Get PDF
    In this paper we report information about the sexual maturity process of 245 Octopus vulgaris specimens (75 females and 170 males) from the Mediterranean Sea. For both sexes, six stages of sexual maturity (immature, developing, maturing, mature, spawning, and spent) are identified on the basis of macroscopic and microscopic observations of the reproductive system and linked with some reproductive indices. A good correspondence between gonad appearance and its histological structure is observed, highlighting, in females, how oviducal gland morphology plays a crucial role in the macroscopic evaluation of maturity. The Gonadosomatic and Hayashi indices, in the two genders, and the Oviducal Gland index in females alone do not allow distinguishing all the stages in an irrefutable way. Data on the potential fecundity, oocyte and spermatophore size are reported and compared with literature. In addition, spermatophore components are also computed. The results reported in this paper lead to easy identification of the different phases of sexual maturation of O. vulgaris and could constitute an important tool for defining assessment models in view of sound management of this species

    Synthesis of cyclobutane-fused oxazolidine-2-thione derivatives

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    An expedient, solvent-free, mild base catalyzed intermolecular cyclization reaction has been developed to enable the one-pot synthesis of fourteen examples of cyclobutane-fused oxazolidine-2-thiones in good to high yields. Bicyclic structures of this type have not previously been described in the literature; they have a cis ring junction with both rings deviating slightly from planarity

    Live Wire - A Low-Complexity Body Channel Communication System for Landmark Identification

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    This paper presents a robust simplex Body Channel Communication (BCC) system aimed at providing an interactive infrastructure solution for visually impaired people. Compared to existing BCC solutions, it provides high versatility, weara- bility and installability in an environment in a low complexity hardware-software solution. It operates with a ground referred transmitter (TX) and it is based on an asynchronous thresh- old receiver (RX) architecture. Synchronization, demodulation and packetizing and threshold control are completely software defined and implemented using MicroPython. The RX includes Bluetooth® (BT) radio connectivity and a cell-phone application provides push text-to-speech notifications to a smartphone. The hardware achieves a Packet Error Rate (PER) of ∼0.1 at 550 kHz pulse center frequency, Synchronized-On Off Keying (S- OOK) modulation and 1 kbps data rate, for an average current consumption of 44mA
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