Ab initio insights into the interaction mechanisms between H2_2, H2_2O, and O2_2 molecules with diamond surfaces

Diamond displays outstanding chemical, physical, and tribological properties, making it attractive for numerous applications ranging from biomedicine to tribology. However, the reaction of the materials with molecules present in the air, such as oxygen, hydrogen, and water, could significantly change the electronic and tribological properties of the films. In this study, we performed several density functional theory calculations to construct a database for the adsorption energies and dissociation barriers of these molecules on the most relevant diamond surfaces, including C(111), C(001), and C(110). The adsorption configurations, reaction paths, activation energies, and their influence on the structure of diamond surfaces are discussed. The results indicate that there is a strong correlation between adsorption energy and surface energy. Moreover, we found that the dissociation processes of oxygen molecules on these diamond surfaces can significantly alter the surface morphology and may affect the tribological properties of diamond films. These findings can help to advance the development and optimization of devices and antiwear coatings based on diamond

Fuzzy Dark Matter candidates from string theory

String theory has been claimed to give rise to natural fuzzy dark matter candidates in the form of ultralight axions. In this paper we revisit this claim by a detailed study of how moduli stabilisation affects the masses and decay constants of different axion fields which arise in type IIB flux compactifications. We find that obtaining a considerable contribution to the observed dark matter abundance without tuning the axion initial misalignment angle is not a generic feature of 4D string models since it requires a mild violation of the Sf ≲ MP bound, where S is the instanton action and f the axion decay constant. Our analysis singles out C4-axions, C2-axions and thraxions as the best candidates to realise fuzzy dark matter in string theory. For all these ultralight axions we provide predictions which can be confronted with present and forthcoming observations

MRS study of meningeal hemangiopericytoma and edema: A comparison with meningothelial meningioma

Intracranial hemangiopericytomas (HPCs) are rare tumors and their radiological appearance resembles that of meningiomas, especially meningothelial meningiomas. To increase the knowledge on the biochemical composition of this type of tumor for better diagnosis and prognosis, we performed a molecular study using ex vivo high resolution magic angle spinning (HR-MAS) magnetic resonance spectroscopy (MRS) perfomed on HPC and peritumoral edematous tissues. Moreover, to help in the discrimination between HPC and meningothelial meningioma we compared the ex vivo HR-MAS spectra of samples from one patient with HPC and 5 patients affected by meningothelial meningioma. Magnetic resonance imaging (MRI), in vivo localized single voxel 1H-MRS was also performed on the same patients prior to surgery and the in vivo and ex vivo MRS spectra were compared. We observed the presence of OH-butyrate, together with glucose in HPC and a low amount of N-acetylaspartate in the edema, that may reflect neuronal alteration responsible for associated epilepsy. Many differences between HPC and meningothelial meningioma were identified. The relative ratios of myo-inositol, glucose and gluthatione with respect to glutamate are higher in HPC compared to meningioma; whereas the relative ratios of creatine, glutamine, alanine, glycine and choline-containing compounds with respect to glutamate are lower in HPC compared to meningioma. These data will be useful to improve the interpretation of in vivo MRS spectra resulting in a more accurate diagnosis of these rare tumors

Singling out the effect of quenched disorder in the phase diagram of cuprates

We investigate the specific influence of structural disorder on the suppression of antiferromagnetic order and on the emergence of cuprate superconductivity. We single out pure disorder, by focusing on a series of Y$_{z}$Eu$_{1-z}$Ba$_2$Cu$_3$O$_{6+y}$ samples at fixed oxygen content $y=0.35$, in the range $0\le z\le 1$. The gradual Y/Eu isovalent substitution smoothly drives the system through the Mott-insulator to superconductor transition from a full antiferromagnet with N\'eel transition $T_N=320$ K at $z=0$ to a bulk superconductor with superconducting critical temperature $T_c=18$ K at $z=1$, YBa$_2$Cu$_3$O$_{6.35}$. The electronic properties are finely tuned by gradual lattice deformations induced by the different cationic radii of the two lanthanides, inducing a continuous change of the basal Cu(1)-O chain length, as well as a controlled amount of disorder in the active Cu(2)O$_2$ bilayers. We check that internal charge transfer from the basal to the active plane is entirely responsible for the doping of the latter and we show that superconductivity emerges with orthorhombicity. By comparing transition temperatures with those of the isoelectronic clean system we deterime the influence of pure structural disorder connected with the Y/Eu alloy.Comment: 10 pages 11 figures, submitted to Journal of Physics: Condensed Matter, Special Issue in memory of Prof. Sandro Massid

HR-MAS NMR spectroscopy in the characterization of human tissues: Application to healthy gastric mucosa

The HR-MAS is an ideal technique for the investigation of intact tissue specimens (10-50 mg) and permits the obtainment of spectra with a resolution comparable to that observed in solution in a time that does not exceed a half of an hour for a routine analysis. The potentialities of HR-MAS NMR spectroscopy in the identification of the metabolites characterizing the healthy gastric mucosa are here presented. The direct 1D H-1 NMR spectra enables only few metabolites to be confidently assigned, and the use of selected 2D experiments strongly amplify the analytical effectiveness of the technique

In vitro ruminal dry matter and neutral detergent fibre digestibility of common feedstuffs as affected by the addition of essential oils and their active compounds

The effects of essential oils (EO) and their active compounds (EOC) on dry matter digestibility and neutral detergent fibre digestibility (DMD and NDFD, respectively) are still not enough described since in vitro methods are limited. So, the aim of the study was to screen and compare the main effects of EO and EOC on short-term DMD and NDFD using the in vitro method. The addition of phenylpropanoid-rich cinnamon oil (CIN) and clove oil (CLO), terpenoid-rich thyme oil (THY) and oregano oil (ORG), and four EOC: cinnamaldehyde (CIN-C), eugenol (EUG), thymol (THY-C) and carvacrol (CAR) was studied at a dose of 0.5 mg ? l?1 of main active compound. Products were tested on four substrates: lucerne hay, soyabean meal, maize meal and a total mixed ration (TMR). Digestibility was determined at 4 and 24 h of fermentation. Both CIN and CIN-C increased NDFD4 of lucerne and maize meal, and decreased NDFD24 of soyabean meal; while CIN-C reduced NDF24 of TMR and CIN reduced DMD of soyabean at both examined hours. CLO and EUG decreased the NDFD24 of soyabean meal improving its DMD24. Also initial DMD of lucerne was increased by both these factors. Only CLO reduced NDFD24 of maize meal. Both THY and THY-C reduced DMD4 of soyabean meal; however only THY-C improved NDF4 of lucerne and reduced NDFD24 of soyabean meal and TMR. DMD24 of most substrates (except lucerne) was reduced by ORE, but not by CAR which improved NDFD4 of lucerne. The in vitro method was sensitive to variations in digestibility caused by EO and EOC, providing a promising approach for the incorporation of EO and EOC effects in systems for cattle diet formulationauthorsversionPeer reviewe

NEW SECONDARY METABOLITES IN THE AMPHINOMID FIREWORM HERMODICE CARUNCULATA

Eight betaine-derived novel compounds were found in extracts of the Mediterranean stinging fireworm Hermodice carunculata. The identification of their structures relies on 1D and 2D NMR (Fig. 1-3) and HPLC-ESI/HRMS spectra. Two types of terminal ammonium portions A and B and a series of different alkyl chains were identified (Fig. 4a,b). Their matching provides the structures of uncharacterized secondary metabolites, named carunculines, and their related isomers. These molecules differ from already known trimethylammonium inflammatory compounds (i.e. complanines) isolated from another amphinomid species, for the structures of the terminal ammonium groups (Fig. 4c) [1]. Carunculine anatomical distribution within H. carunculata was assessed by screening through HPLC-ESI/HRMS (Fig. 5, Table 1): their occurrence was revealed in all the body parts analyzed, both involved in predator-prey interactions [2], and mainly in the digestive apparatus. The results achieved reveal an array of different novel compounds from a chemically unknown species, improving knowledge on Marine Animal Products with chemical and biological potential for bioprospection [3]. Overall, these data reinforce the necessity of studying poorly-investigated taxa to expand knowledge on animal venom biology, their mechanisms of action and exploitation as promising source of drug molecule

Perspectives of 2D MXene Tribology

The Large and Rapidly Growing Family of 2D Early Transition Metal Carbides, Nitrides, and Carbonitrides (MXenes) Raises Significant Interest in the Materials Science and Chemistry of Materials Communities. Discovered a Little More Than a Decade Ago, MXenes Have Already Demonstrated Outstanding Potential in Various Applications Ranging from Energy Storage to Biology and Medicine. the Past Two Years Have Witnessed Increased Experimental and Theoretical Efforts toward Studying MXenes\u27 Mechanical and Tribological Properties When Used as Lubricant Additives, Reinforcement Phases in Composites, or Solid Lubricant Coatings. Although Research on the Understanding of the Friction and Wear Performance of MXenes under Dry and Lubricated Conditions is Still in its Early Stages, It Has Experienced Rapid Growth Due to the Excellent Mechanical Properties and Chemical Reactivities Offered by MXenes that Make Them Adaptable to Being Combined with Other Materials, Thus Boosting their Tribological Performance. in This Perspective, the Most Promising Results in the Area of MXene Tribology Are Summarized, Future Important Problems to Be Pursued Further Are Outlined, and Methodological Recommendations that Could Be Useful for Experts as Well as Newcomers to MXenes Research, in Particular, to the Emerging Area of MXene Tribology, Are Provided

Ex vivo HR-MAS Magnetic Resonance Spectroscopy of human gastric adenocarcinomas: A comparison with healthy gastric mucosa

The present study reports the characteristics of the biochemical profile of human gastric adenocarcinoma in comparison with that of healthy gastric mucosa, using ex vivo HR-MAS Magnetic Resonance Spectroscopy. Healthy human mucosa is mainly characterized by the presence of small metabolites (more than 50 identified) and macromolecules, whereas the adenocarcinoma spectra are dominated by the presence of signals due to triglycerides, whose content on the contrary is very low in healthy gastric mucosa. The use of spin-echo experiments enable us to detect some metabolites in the unhealthy tissues and to determine their variation with respect to the healthy ones. We have observed that the Cho:ChoCC ratio changes from 20:80 in the healthy tissues to 80:20 in the neoplastic gastric mucosa

Ileocecal Fistula Caused by Multiple Foreign Magnetic Bodies Ingestion

The incidence of accidental foreign body (FBs) ingestion is 100,000 cases/year in the US, with over than 80% of cases occurring in children below 5 years of age. Although a single FB may pass spontaneously and uneventfully through the digestive tract, the ingestion of multiple magnetics can cause serious morbidity due to proximate attraction through the intestinal wall. Morbidity and mortality depend on a prompt and correct diagnosis which is often difficult and delayed due to the patient's age and because the accidental ingestion may go unnoticed. We report our experience in the treatment of an 11-year-old child who presented to the emergency department with increasing abdominal pain, vomiting, diarrhea, and fever. Surgery evidenced an ileocecal fistula secondary to multiple magnetic FB ingestion with attraction by both sides of the intestinal wall. A 5-centimeter ileal resection was performed, and the cecal fistula was closed with a longitudinal manual suture. The child was discharged at postoperative day 8. After one year, the patient's clinical condition was good