Heat Treatment of Steels

Steels represent an interesting family of materials, both from a scientific and commercial point of view, considering the many innovative applications they can be used for [...]

Clinical case of papulo-pustular rosacea

The article presents a clinical case of papulopustular rosacea from our own practice. First of all, the patient's anamnesis is extremely interesting: family history (his brother has episodes of reddening of the face), the onset of rosacea against the background of a stressful situation, the presence of gastric diseases, the connection with nutritional factors. One of the first mentions of rosacea belongs to Avicenna, who in his writings described the clinical picture of rhinophyma ("badschenan", later renamed "abedsamen"). The pineal nose, dotted with "serpentine" vessels, has traditionally been associated with excessive drinking. Currently, the role of alcohol as an etiological factor is not paramount, but its aggravating effect has been proven. Despite the typical picture of rosacea, our patient has been receiving therapy for seborrheic dermatitis and other diseases several times over the course of several years. Probably, the specialists had doubts about the possible diagnosis of rosacea in a male patient under the age of 30.

New horseshoe crab fossil from Germany demonstrates post-Triassic extinction of Austrolimulidae

Horseshoe crabs within Austrolimulidae represent the extreme limits to which the xiphosurid Bauplan could be modified. Recent interest in this group has uncovered an unprecedented diversity of these odd-ball xiphosurids and led to suggestions that Austrolimulidae arose during the Permian Period and had become extinct by the end of the Triassic Period. Here, we extend the temporal record of Austrolimulidae by documenting a new horseshoe crab from the Lower Jurassic (Hettangian) Bayreuth Formation, Franconiolimulus pochankei gen. et sp. nov. The novel specimen displays hypertrophied genal spines, a key feature indicative of Austrolimulidae, but does not show as prominent accentuation or reduction of other exoskeletal sections. In considering the interesting family, we explore the possible origins and explanations for the bizarre morphologies exhibited by the Austrolimulidae and present hypotheses regarding the extinction of the group. Further examination of horseshoe crab fossils with unique features will undoubtedly continue to increase the diversity and disparity of these curious xiphosurids.

Maxwellian evolution equations along the uniform optical fiber in Minkowski space

We firstly discuss the geometric phase rotation for an electromagnetic wave traveling along the optical fiber in Minkowski space. We define two types of novel geometric phases associated with the evolution of the polarization vectors in the normal and binormal directions along the optical fiber by identifying the normal-Rytov parallel transportation law and binormal-Rytov parallel transportation law and derive their relationships with the new types of Fermi-Walker transportation law in Minkowski space. Then we describe a novel approach of solving Maxwell's equations in terms of electromagnetic field vectors and geometric quantities associated with the curved path characterizing the path uniform optical fiber by using the traveling wave transformation method. Finally, we investigate that electromagnetic wave propagation along the uniform optical fiber admits an interesting family of Maxwellian evolution equation having numerous physical and geometric applications for anholonomic coordinate system in Minkowski space

ANGEL: efficient, and effective, node-centric community discovery in static and dynamic networks

Community discovery is one of the most challenging tasks in social network analysis. During the last decades, several algorithms have been proposed with the aim of identifying communities in complex networks, each one searching for mesoscale topologies having different and peculiar characteristics. Among such vast literature, an interesting family of Community Discovery algorithms, designed for the analysis of social network data, is represented by overlapping, node-centric approaches. In this work, following such line of research, we propose Angel, an algorithm that aims to lower the computational complexity of previous solutions while ensuring the identification of high-quality overlapping partitions. We compare Angel, both on synthetic and real-world datasets, against state of the art community discovery algorithms designed for the same community definition. Our experiments underline the effectiveness and efficiency of the proposed methodology, confirmed by its ability to constantly outperform the identified competitors.

Nearly free curves and arrangements: a vector bundle point of view

Over the past forty years many papers have studied logarithmic sheaves associated to reduced divisors, in particular logarithmic bundles associated to plane curves. An interesting family of these curves are the so-called free ones for which the associated logarithmic sheaf is the direct sum of two line bundles. Terao conjectured thirty years ago that when a curve is a finite set of distinct lines (i.e. a line arrangement) its freeness depends solely on its combinatorics, but this has only been proved for sets of up to 12 lines. In looking for a counter-example to Terao’s conjecture, the nearly free curves introduced by Dimca and Sticlaru arise naturally. We prove here that the logarithmic bundle associated to a nearly free curve possesses a minimal non-zero section that vanishes on one single point, P say, called the jumping point, and that this characterises the bundle. We then give a precise description of the behaviour of P. Based on detailed examples we then show that the position of P relative to its corresponding nearly free arrangement of lines may or may not be a combinatorial invariant, depending on the chosen combinatorics.

Discovery of Novel Glycerolated Quinazolinones from Streptomyces sp. MBT27

Actinobacteria are a major source of novel bioactive natural products. A challenge in the screening of these microorganisms lies in finding the favorable growth conditions for secondary metabolite production and dereplication of known molecules. Here, we report that Streptomyces sp. MBT27 produces 4-quinazolinone alkaloids in response to elevated levels of glycerol, whereby quinazolinones A (1) and B (2) form a new sub-class of this interesting family of natural products. Global Natural Product Social molecular networking (GNPS) resulted in a quinazolinone-related network that included anthranilic acid (3), anthranilamide (4), 4(3H)-quinazolinone (5) and 2,2-dimethyl-1,2-dihydroquinazolin-4(3H)-one (6). Actinomycins D (7) and X2 (8) were also identified in the extracts of Streptomyces sp. MBT27. The induction of quinazolinone production by glycerol combined with biosynthetic insights provide evidence that glycerol is integrated into the chemical scaffold. The unprecedented 1,4-dioxepane ring that is spiro-fused into the quinazolinone backbone, is most likely formed by intermolecular etherification of two units of glycerol. Our work underlines the importance of varying the growth conditions for the discovery of novel natural products and for understanding their biosynthesis.

Synthesis and Application of Thiosquaramides and Their Derivatives: A Review

Thiosquaramides are the thio analogues of squaramides that are widely applicable in the fields of asymmetric catalysis, pharmaceutical research, and chemical biology. Having four-membered ring system derived from squaric acid, thiosquaramides are feasible hydrogen bond donors and acceptors. A high affinity for hydrogen bonding is driven through a concomitant increase in aromaticity of the ring. In this review the structural properties, acidity, and lipophilicity of thiosquaramides and squaramides are compared. Different synthetic procedures starting from squarates, half-squaramides or squaramides are shown, and the main derivatization methods are outlined. Finally, the yet only few applications of this interesting family are reviewed. Considering their hydrogen bonding and aromatic switching, in combination with structural rigidity, they bear the possibility of becoming robust and tunable bifunctional organocatalysts for a range of synthetically useful transformations in the future.