In Situ Observations during Chemical Vapor Deposition of Hexagonal Boron Nitride on Polycrystalline Copper.

Using a combination of complementary in situ X-ray photoelectron spectroscopy and X-ray diffraction, we study the fundamental mechanisms underlying the chemical vapor deposition (CVD) of hexagonal boron nitride (h-BN) on polycrystalline Cu. The nucleation and growth of h-BN layers is found to occur isothermally, i.e., at constant elevated temperature, on the Cu surface during exposure to borazine. A Cu lattice expansion during borazine exposure and B precipitation from Cu upon cooling highlight that B is incorporated into the Cu bulk, i.e., that growth is not just surface-mediated. On this basis we suggest that B is taken up in the Cu catalyst while N is not (by relative amounts), indicating element-specific feeding mechanisms including the bulk of the catalyst. We further show that oxygen intercalation readily occurs under as-grown h-BN during ambient air exposure, as is common in further processing, and that this negatively affects the stability of h-BN on the catalyst. For extended air exposure Cu oxidation is observed, and upon re-heating in vacuum an oxygen-mediated disintegration of the h-BN film via volatile boron oxides occurs. Importantly, this disintegration is catalyst mediated, i.e., occurs at the catalyst/h-BN interface and depends on the level of oxygen fed to this interface. In turn, however, deliberate feeding of oxygen during h-BN deposition can positively affect control over film morphology. We discuss the implications of these observations in the context of corrosion protection and relate them to challenges in process integration and heterostructure CVD.P.R.K. acknowledges funding from the Cambridge Commonwealth Trust and the Lindemann Trust Fellowship. R.S.W. acknowledges a research fellowship from St. John’s College, Cambridge. S.H. acknowledges funding from ERC grant InsituNANO (no. 279342), EPSRC under grant GRAPHTED (project reference EP/K016636/1), Grant EP/H047565/1 and EU FP7 Work Programme under grant GRAFOL (project reference 285275). The European Synchrotron Radiation Facility (ESRF) is acknowledged for provision of synchrotron radiation and assistance in using beamline BM20/ROBL. We acknowledge Helmholtz-Zentrum-Berlin Electron storage ring BESSY II for synchrotron radiation at the ISISS beamline and continuous support of our experiments.This is the final version. It was first published by ACS at http://pubs.acs.org/doi/abs/10.1021/cm502603

Utjecaj toksičnosti metala na reprodukcijsku funkciju u muškaraca

A combination of genetic, environmental and lifestyle factors contributes to adverse effects on the reproductive health in men. Metals are pervasive in food, water, air, tobacco smoke, and alcoholic beverages. Experimental studies suggest that many metals have adverse effects on the male reproductive function. However, information about reproductive effects of human exposure to metals is scarce and/or inconsistent. This review summarises the information from epidemiological studies of the effects of metal exposure on reproductive function in men. Factors capable of affecting these relationships were identifi ed and discussed. A particular attention is given to the studies considering influence of concomitant exposure to various metals. These studies have generally confirmed that even moderate- to low-level exposure to lead affects certain reproductive parameters, and that exposure to cadmium affects the prostate function and serum testosterone levels. Adverse effects of mercury, manganese, chromium and arsenic on semen quality and altered serum hormone are less well documented. There is no clear evidence that boron exposure may impair reproductive health in men. Only a few studies have investigated reproductive effects of concomitant exposure to several metals and controlled for potential confounders. Future studies should consider the contribution of combined exposure to various metals and/or other factors that may influence individual susceptibility to reproductive health impairment in men.Postoje indikacije da kombinacija genetskih, okolišnih i čimbenika načina života pridonosi uočenom poremećaju reprodukcijskog zdravlja u muškaraca. Metali su široko rasprostranjeni u čovjekovu okolišu te u hrani, vodi, zraku, cigaretnom dimu i alkoholnim pićima. Rezultati eksperimentalnih istraživanja sugeriraju štetne učinke većine ispitivanih metala na mušku reprodukcijsku funkciju. Međutim, odgovarajuća su istraživanja u ljudi oskudna. Ovaj rad sažima rezultate dosadašnjih epidemioloških istraživanja o učincima izloženosti metalima na mušku reprodukcijsku funkciju. Poseban naglasak dan je istraživanjima koja su razmatrala utjecaj istodobne izloženosti različitim metalima uz čimbenike čovjekova načina života i njihovo međudjelovanje na reprodukcijske učinke. Objavljeni rezultati daju dovoljno dokaza o štetnom djelovanju olova i žive na neke reprodukcijske parametre te kadmija na poremećaj prostate i razinu testosterona u serumu, čak u uvjetima umjerene do niske razine izloženosti. Manje je dokaza o štetnom djelovanju na kvalitetu sjemena i razinu spolnih hormona nađeno za mangan. Podaci koji upućuju na moguće štetno djelovanje arsena ili kroma nisu dosljedni, dok o štetnom djelovanju bora na mušku reprodukcijsku funkciju nema jasnih podataka. Utjecaj potencijalno uzročnih varijabli uzet je u obzir samo u nekoliko radova. Stoga buduća istraživanja poremećaja reprodukcijskog zdravlja u muškaraca trebaju razmatrati doprinos istovremene izloženosti različitim metalima koji u kombinaciji s ostalim čimbenicima mogu utjecati na osobnu (pre)osjetljivost

Palatalization in Ukrainian, Polish and Russian. A pilot 3D Ultrasound Study

The paper reports findings of a pilot 3D/4D ultrasound study on the articulation of palatalized coronal obstruents in Ukrainian, Polish and Russian. The study quantitatively evaluates the degree of palatalization looking at the relative dorsum frontings/dorsum raising/ advancement of the tongue root as variables. Apart from the fronting and raising of the tongue dorsum, palatalized consonants show a systematic effect of the advancement of the tongue root. The preliminary results indicate that the effect of the position of the dorsum is bigger in phonemic palatalization than in allophonic palatalization, while the effect size of the tongue root remains similar across palatalization types

Comparison of essential oil composition of Stachys menthifolia Vis. from two natural habitats in Croatia

Stachys menthifolia Vis. is an endemic species from the Balkan Peninsula. Aerial parts of the plant were collected from its natural habitat near Dubrovnik. Hydrodistilled volatile oil obtained from the plant material of S. menthifolia was subjected to gas chromatographic analysis coupled to mass spectrometry. More than 70 compounds were identified, representing 94.5% of the total oil. The major constituents of the oil were diterpenoid abietatriene (11.7%), and sesquiterpene hydrocarbons α-bisabolene (8.4%), and β-caryophyllene (7.4%). Presented results are comparable to our previous findings on essential oil composition of the same species from Biokovo Mountain, with small differences in quantitative and qualitative constitution of the oil. Although plants belonging to the Stachys genus show significant variability in their chemical compositions depending on the location and stage of plant development, this work indicates that chemical polymorphism of endemic S. menthifolia does not manifest in the region of Croatian Mediterranean area

Negation of Croatian Nouns

The purpose of this paper is to describe a morphological grammar for recog-nizing negation of a noun and annotating its polarity accordingly. Not all nouns can be negated on the morphological level. For example, nouns like ‘activity’ and ‘knowledge’ (aktivnost, znanje) can have negatives (neak-tivnost, neznanje respectfully), but the same is not the case for nouns such as ‘battle’ or ‘table’ (bitka or stol). The most common and frequent Croatian prefix for negation of nouns is ‘ne-’ although several more are used either of Slavic (‘be-‘, ‘bez-‘) or Latin origin (‘anti-‘, ‘dis-‘). In some cases, negated nouns actually denote positive concepts, whereas their non-negated counter-parts are used for expressing concepts with negative connotations. For this purpose, all the nouns in NooJ dictionary, that may have nouns in both po-larities, are provided with [Polarity=pos] or [Polarity=neg] marker. This in-formation is used in the grammar to switch the polarity of the opposite noun after the insertion of a negative prefix. The grammar is tested on different types of corpora and results are discussed