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We study the underlying chemical, electronic, and magnetic properties of a number of magnetite-based thin films. The main focus is placed onto ${\mathrm{Fe}}_{3}{\mathrm{O}}_{4}$(001)/NiO bilayers grown on MgO(001) and Nb-${\mathrm{SrTiO}}_{3}$(001) substrates. We compare the results with those obtained on pure ${\mathrm{Fe}}_{3}{\mathrm{O}}_{4}$(001) thin films. It is found that the magnetite layers are oxidized and ${\mathrm{Fe}}^{3+}$ dominates at the surfaces due to maghemite ($\ensuremath{\gamma}\text{\ensuremath{-}}{\mathrm{Fe}}_{2}{\mathrm{O}}_{3}$) formation, which decreases with increasing magnetite layer thickness. For layer thicknesses of around 20 nm and above, the cationic distribution is close to that of stoichiometric ${\mathrm{Fe}}_{3}{\mathrm{O}}_{4}$. At the interface between NiO and ${\mathrm{Fe}}_{3}{\mathrm{O}}_{4}$ we find the Ni to be in a divalent valence state, with unambiguous spectral features in the Ni $2p$ core level x-ray photoelectron spectra typical for NiO. The formation of a significant ${\mathrm{NiFe}}_{2}{\mathrm{O}}_{4}$ interlayer can be excluded by means of x-ray magnetic circular dichroism. Magneto-optical Kerr effect measurements reveal significant higher coercive fields compared to magnetite thin films grown on MgO(001), and an altered in-plane easy axis pointing in the $\ensuremath{\langle}100\ensuremath{\rangle}$ direction. We discuss the spin magnetic moments of the magnetite layers and find that a thickness of 20 nm or above leads to spin magnetic moments close to that of bulk magnetite.

XPS measurements of coarse-grained and nanostructured nitinol (Ni 50.2Ti49.8) before and after chemical treatment in hydrofluoric acid (40% HF, 1 min) are presented. The nanostructured state, providing the excellent mechanical properties of nitinol, is achieved by severe plastic deformation. The near-surface layers of nitinol were studied by XPS depth profiling. According to the obtained results, a chemical treatment in hydrofluoric acid reduces the thickness of the protective TiO2 oxide layer and induces a nickel release from the nitinol surface and an arsenic contamination, and can therefore not be recommended as conditioning to increase the roughness of NiTi-implants. A detailed evaluation of the resulting toxicological risks is given. © 2012 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2012. Copyright © 2012 Wiley Periodicals, Inc.

North America has a growing problem with invasive aquatic plants. At every level of the aquatic food web, long-standing checks and balances have become dramatically eroded by the introduction of non-native species. The northeastern United States contains thousands of diverse freshwater habitats, highly heterogeneous in geology and locale, where nuisance aquatic plant growth results in decreased lake water quality, interference with recreational access, degraded flood control structures, and impacts to their aesthetic quality. Early infestation and spread of exotic species is often poorly documented at local and state levels. Consequently, successful management of these species depends on continuous monitoring and definitive identification by both public officials and waterside homeowners. With new mapping capabilities employing software such as Geographic Information Systems (GIS) coupled with the growing computerization of taxonomic records and online availability of regional herbarium records, we have been able to illustrate the temporal and geographic spread of these species, thus enabling aquatic ecologists and managers to make predictions of future infestations. In this paper we evaluate these techniques focusing on three of the most pervasive of exotic aquatic plant species in New York State: Myriophyllum spicatum, Trapa natans and Potamogeton crispus.

The electronic structure of the strongly Coulomb correlated cuprate CuGeO3 has been calculated by the local-density-approximation method (LDA+U). The parameter U was varied from 0 to 8 eV. The results of the band-structure calculations are compared with experimental data obtained by means of X-ray photoelectron and resonant X-ray emission spectroscopy methods (Cu Lalpha and O Kalpha X-ray emission spectra). It is established that a LDA+U calculation with U = 4 eV reproduces well the X-ray photoelectron and X-ray resonant emission spectral data.

Drinking water standards and recreational demands on lakes and ponded waters place a high priority on the management of water quality. As stakeholders, volunteer citizen monitors can provide considerable assistance to state agencies and research organizations charged with monitoring freshwater resources by accumulating valuable data for water quality evaluation and lake assessment. The Lay Monitoring Program on Lake George (NY) was initiated in 1980 concomitant with the establishment of a long-term chemical monitoring program. By 2002, 23 years of Secchi transparency and surface temperature data had been collected. Results have revealed potential relationships between variations in Secchi transparency and trophic indicators (chlorophyll a and total phosphorus) and have assisted in evaluating the potential influences of both increased recreational use and precipitation regime. Lay monitor participation provides a valuable and cost effective enhancement for ongoing lake chemical and biotic effect s...

The Mn X-ray emission spectra and X-ray photoelectron spectra of Mn-based Heusler alloys Co 2 MnAl, Co 2 MnSb and La 1− x Sm x Mn 2 Si 2 rare-earth compounds ( x =0, 0.8) have been measured and discussed in connection with a value of the local magnetic moment at Mn site. The spectra peculiarities reflect also the localization degree of 3d valence electrons of 3d metals in the considered compounds and could be used as an indicator of the closeness of the density of states to half-metallic character.

A full study of the electronic structures of FeCr2S4 and Fe0.5Cu0.5Cr2S4 is reported based on x-ray photoelectron spectra (valence band and core levels), x-ray emission spectra (Fe Lα, Cu Lα, Cr Lα, S Kβ1,3 and S L2,3) and ab initio TB-LMTO band structure calculations. In the valence band of FeCr2S4, the Fe 3d states are found to be more localized than the Cr 3d states, which dominate at the Fermi level. In Fe0.5Cu0.5Cr2S4, the distribution of Cr 3d (Cr3+) states is unchanged and the Cu ions were found to be in the Cu+ state.

The electronic structure of LiMnO2 and Li2MnO3 was studied by means of X-ray photoelectron and soft X-ray emission spectroscopy. For LiMnO2, LSDA and LSDA+U calculations were carried out. The LSDA+U calculations are in rather good agreement with the measured valence-band structure as well as with the magnetic and electrical properties of LiMnO2. It is shown that the band gap in LiMnO2 is determined by the charge-transfer effect.

The results of measurements of X-ray photoelectron (XPS), X-ray emission (XES) and X-ray absorption spectra and LSDA band structure calculations of Pr0.5Sr0.5MnO3 are presented. The excitation energy dependence of Mn L2,3 and O Kα X-ray emission spectra of Pr0.5Sr0.5MnO3 is measured using tunable synchrotron radiation. Comparing XPS and XES measurements and the LSDA band structure calculations, one concludes that the Mn 3d states are localized near the top of the valence band. Some differences in the Mn 3d-distribution in the upper part of the XPS valence band and Mn L3 XES are due to spin selection rules.

The results of measurements of x-ray photoelectron (XPS), x-ray emission (XES), and x-ray absorption spectra and local spin-density approximation band structure (LSDA) calculations of ${\mathrm{Pr}}_{0.5}{\mathrm{Sr}}_{0.5}{\mathrm{MnO}}_{3}$ are presented. The excitation energy dependence of Mn ${L}_{2,3}$ and O $K\ensuremath{\alpha}$ x-ray emission spectra of ${\mathrm{Pr}}_{0.5}{\mathrm{Sr}}_{0.5}{\mathrm{MnO}}_{3}$ is measured using tunable synchrotron radiation. The XES measurements yielded no photon energy dependence for the O $K\ensuremath{\alpha}$ spectra, but the Mn ${L}_{2,3}$ spectra yielded inelastic scattering losses of 2 and 6 eV, corresponding to features in the structure of the occupied part of the valence band. Comparing XPS and XES measurements with LSDA band-structure calculations, one concludes that the electronic structure of the compound consists mainly of Mn $3d$ and O $2p$ states. States of $3d$ character localized at the Mn site predominate near the top of the valence band (VB). Some differences in the Mn $3d$ distribution in this part of the XPS valence band and Mn ${L}_{3}$ XES with d symmetry due to spin-selection rules that govern the Mn ${L}_{3}$ XES. In addition, the Mn $3d$ states distribution is hybridized with the O $2p$ part of the VB. Mn ${L}_{3}$ XES spectra were determined relative to the Fermi energy by assuming normal x-ray emission begins from the lowest level of the ${p}^{5}{d}^{n+1}L$ intermediate state (which is the Mn $2p$ ionizatation threshold). From the local spin-density approximation, the orbital character of the Mn $3d$ electrons can be assigned ${e}_{g}$ symmetry at the top of the valence band ${T}_{2g}$ in the central part of the VB, and equal contributions of ${e}_{g}$ and ${t}_{2g}$ states at the bottom of the valence band.

A VO2 single-crystal has been subject of a combined investigation by high resolution XPS, x-ray emission spectroscopy with electron and energy-selective x-ray excitation (V L-alpha, V K-beta-5- and O K-alpha emission) and x-ray absorption spectroscopy (O1s). We performed first principles tight-binding LMTO band structure calculations of VO2 in both monoclinic and tetragonal rutile structures and compare the densities of states with the experimental data. From this we conclude that the electronic structure of VO2 is more bandlike than correlated.

The electronic structure of LiCu${}_{2}$O${}_{2}$ was studied using x-ray emission (Cu ${L}_{\ensuremath{\alpha}},$ O ${K}_{\ensuremath{\alpha}})$ and photoelectron spectroscopy (valence band and core levels) as well as band-structure calculations in terms of local spin-density approximation (LSDA) and LSDA+$U$ approaches. According to the x-ray-emission and photoelectron spectra the valence states of the Cu atoms are found to be mixed, i.e., 2+ and 1+. The LSDA calculations are contradictory to the experimental data and cannot reproduce the band gap and magnetic properties of ${\mathrm{LiCu}}_{2}{\mathrm{O}}_{2}$. The LSDA+$U$ calculations describe the insulator and antiferromagnetic properties much better but the overestimation of the screened Coulomb parameter $U$ leads to a binding-energy shift of the Cu${}^{\mathrm{II}}$ $3d$ states and this distorts the proper modeling of the valence-band structure. The magnetic structure of LiCu${}_{2}$O${}_{2}$ is discussed, taking our LSDA+$U$ band-structure calculations into account.

Results of first measurements of X-ray emission spectra (Ni Lα, Cu Lα and B Kα) and X-ray photoelectron spectra (valence band and core levels) of YNi1−xCuxBC (x = 0.1-0.55) are presented. It is found that Ni and Cu 3d-states have predominantly metallic character and provide the main contribution to the density of states at the Fermi level N(Ef). N(Ef) progressively increases with x and correlates well with the magnetic susceptibility measurements, accounting for the increase in Tc with copper doping. In Ni 2p 3 2 XPS a low intensity high-energy satellite peak is found which can be attributed to two-hole bound states. Selective oxidation of Y-atoms is found under exposure of the freshly cleaved surface of YNi0.6Cu0.4BC to air.

A full study of the electronic structure of 4d and 5d silicides (RuSi, RhSi, PdSi, OsSi, IrSi, , PtSi) is undertaken including XPS VB and XES ( and ) measurements and LMTO band structure calculations. It is found that d bands which dominate the density of states are more localized with increasing atomic number Z of the transition metal. A strong hybridization between silicon 3p and transition metal d states occurs over the entire valence band. Si 3s states are found to be not mixed with Si 3p and nd states but Si 3d states participate in bonding and hybridize with transition metal d states. The non-bonding character of the majority of nd states is not confirmed for 4d and 5d silicides.

The electronic structure of the monoclinic phase of titanium monoxide and a vacancy-free rock-salt phase have been investigated using x-ray photoelectron spectroscopy and x-ray emission spectroscopy techniques. For the investigation of the monoclinic structure type, polycrystalline samples of titanium monoxide were used. The samples of the vacancy-free rock-salt structure have been obtained by annealing monoclinic titanium monoxide at high temperature and pressure. The x-ray powder diffraction pattern of both types of samples revealed single-phase crystals without any substructures. The x-ray photoelectron valence band spectra reveal that the upper, mainly Ti $3d$-derived, part of the valence band is split and that the lower, mostly O $2p$-derived, band exhibits three features. A combined representation of the photoelectron valence band spectrum of the monoclinic phase and O ${K}_{\ensuremath{\alpha}},$ Ti ${L}_{\ensuremath{\alpha}},$ and Ti ${K}_{\ensuremath{\beta}5}$ x-ray emission spectra shows that titanium and oxygen states are hybridized over almost the full valence band region, without a gap. The valence band of the vacancy-free rock-salt phase was found to be wider than that of the monoclinic phase. The experimentally obtained valence band density of states are compared with recent band structure calculations. In addition, we present spectra of the O $1s$ and Ti $2p$ core levels and show the effects of a gradual oxidation of the sample on these spectra.

The delafossite-type ${\mathrm{CuFeO}}_{2}$ single crystal was studied by means of x-ray emission and x-ray photoelectron spectroscopy. The valence state of Cu ions was found to be $1+,$ whereas Fe ions were found to be trivalent in the high-spin $S=5/2$ state. The x-ray emission (Cu ${L}_{\ensuremath{\alpha}},$ Fe ${L}_{\ensuremath{\alpha}},$ and O ${K}_{\ensuremath{\alpha}})$ and photoelectron spectra were compared to the results of the local spin density approximation (LSDA) (full-potential linearized augmented plane wave method and linearized muffin-tin orbitals in atomic sphere approximation method) and $\mathrm{LSDA}+U$ calculations. It is found that the maximum of the Cu $3d$ state distribution is localized closer to the Fermi level than that of the Fe $3d$ states. The LSDA calculations contradict the experimental results and do not give a correct description of the Cu and Fe $3d$ positions relative to the Fermi level, and incorrectly predict metallic behaviors (semiconductor observed) and give qualitatively incorrect magnetic properties of ${\mathrm{CuFeO}}_{2}.$ The $\mathrm{LSDA}+U$ calculations give a much better agreement with the observed valence-band structure, the measured electrical, and the magnetic properties.

Thermogravimetric analysis has revealed that reduction of ${\mathrm{Sr}}_{2}{\mathrm{CuO}}_{2}{\mathrm{F}}_{2+\mathrm{\ensuremath{\delta}}}$ in ${10%\mathrm{}\mathrm{H}}_{2}{/90%\mathrm{}\mathrm{N}}_{2},$ occurs in two distinct steps on heating up to 930 \ifmmode^\circ\else\textdegree\fi{}C. Whereas reduction to give ${\mathrm{SrF}}_{2},$ SrO, and Cu is complete above 800 \ifmmode^\circ\else\textdegree\fi{}C, a stable intermediate forms in the region between 250 and 450 \ifmmode^\circ\else\textdegree\fi{}C. This has been identified as a new tetragonal $(I4/mmm)$ phase, ${\mathrm{Sr}}_{2}{\mathrm{CuO}}_{2}{\mathrm{F}}_{2},$ with unit-cell dimensions $a=3.967(1)\AA{}$ and $c=12.816(2)\AA{}.$ The structure has been determined from powder x-ray-diffraction data and is related to ${\mathrm{Nd}}_{2}{\mathrm{CuO}}_{4}$ (${T}^{\ensuremath{'}}$-type). Madelung energy, bond valence sum calculations, and F $1s$-XPS data clearly indicate that the ${\mathrm{F}}^{\mathrm{\ensuremath{-}}}$ ions occupy sites within the fluorite block $({\mathrm{Sr}}_{2}{\mathrm{F}}_{2})$ insulating layers. This contrasts with the ${\mathrm{La}}_{2}{\mathrm{CuO}}_{4}$ ($T$-type) structure which is adopted by ${\mathrm{Sr}}_{2}{\mathrm{CuO}}_{2}{\mathrm{F}}_{2+\mathrm{\ensuremath{\delta}}}.$

The results of XPS measurements of nanostructured Ti (ns-Ti) prepared with a help of severe plastic deformation (SPD) have been presented. We have measured XPS spectra of core levels (Ti 2p, O 1s, C 1s, F 1s and valence bands before and after treatment of ns-Ti-implants in HF. The obtained data have been compared with XPS measurements of untreated and acid treated coarsegrained Ti (cg-Ti). According to these measurements the surface composition has not practically been changed by reduction of grains size of Ti-implants. It has been found that the surface of both types of implants is covered with thick TiO 2 layer. The acid treatment reduces the surface contamination of ns-Ti and cg-Ti by hydrocarbons and induces better passivation and formation of more thick TiO2 layer. It has been shown that severe plastic deformation not only improves mechanical properties but also preserves corrosion stability of Ti-implants. Copyright © 2012 American Scientific Publishers.

XPS core level spectra of Y123 compounds doped by C, B, S, P, and Se elements are presented. It is found that the C1s, E1s, S2p, P2p, and Se3d binding energies of doped compounds are close to those of CaCO3, FeBO3, CuSO4, NaH2,PO4, and SeO2, reference compounds. It is concluded that these impurity elements form oxyanion groups in Y123 compounds.

The x-ray photoelectron valence-band spectrum and x-ray emission valence-band spectra (Ti K${\mathrm{\ensuremath{\beta}}}_{5}$, Ti L\ensuremath{\alpha}, O K\ensuremath{\alpha}) of ${\mathrm{Bi}}_{4}$${\mathrm{Ti}}_{3}$${\mathrm{O}}_{12}$ are presented (analyzed in the common energy scale) and interpreted on the basis of a band-structure calculation for an idealized I4/mmm structure of this material.

The electronic structure of the high-${\mathit{T}}_{\mathit{c}}$ superconductor ${\mathrm{Sr}}_{2}$${\mathrm{CuO}}_{2}$${\mathrm{F}}_{2+\mathrm{\ensuremath{\delta}}}$ has been investigated by means of x-ray-emission spectroscopy (O ${\mathit{K}}_{\mathrm{\ensuremath{\alpha}}}$, Cu ${\mathit{L}}_{\mathrm{\ensuremath{\alpha}},\mathrm{\ensuremath{\beta}}}$, F ${\mathit{K}}_{\mathrm{\ensuremath{\alpha}}}$), x-ray-photoelectron spectroscopy, and band-structure calculations using the full-potential linear muffin-tin orbital method. The local environment of the F atoms and the valence state of the Cu atoms in ${\mathrm{Sr}}_{2}$${\mathrm{CuO}}_{2}$${\mathrm{F}}_{2+\mathrm{\ensuremath{\delta}}}$ are discussed. On the basis of the x-ray-photoelectron and x-ray-emission spectra it is concluded that the F atoms preferentially bond to Sr atoms in this compound.

Based on ab initio electronic-structure calculations by the linear muffin-tin orbital method and the combined analysis of x-ray photoelectron and x-ray B K\ensuremath{\alpha}, O K\ensuremath{\alpha}, and Fe L\ensuremath{\alpha} emission spectra in a common energy scale, the aspects of hybridization within the valence band of ${\mathrm{FeBO}}_{3}$ are discussed in detail. X-ray photoelectron spectra of ${\mathrm{B}}_{2}$${\mathrm{O}}_{3}$ and ${\mathrm{H}}_{3}$${\mathrm{BO}}_{3}$ have also been obtained and are discussed in comparison with that of ${\mathrm{FeBO}}_{3}$.

LFB1 (HNF1) is a tissue-specific transcription factor found in the livers, stomachs, intestines, and kidneys of vertebrates. By analyzing the promoter of the Xenopus LFB1 gene, we identified potential autoregulation by LFB1 and regulation by HNF4, a transcription factor with a tissue distribution similar to that of LFB1. Injection of LFB1 promoter-chloramphenicol acetyltransferase constructs into Xenopus eggs revealed embryonic activation that is restricted to the region of the developing larvae expressing endogeneous LFB1. Proper embryonic activation was also observed with a rat LFB1 promoter. Deletion analysis of the Xenopus and rat promoters revealed that in both promoters embryonic activation is absolutely dependnet on the presence of an element that contains CCNCTCTC as the core consensus sequence. Since this element is recognized by the maternal factor OZ-1 previously described by N. Ovsenek, A. M. Zorn, and P. A. Krieg (Development 115:649-655, 1992), we might have identified the main constituents of a hierarchy that leads via LFB1 to the activation of tissue-specific genes during embryogenesis.

The transcription factor LFB1 (HNF1) involved in the expression of liver-specific genes is characterized by a serine/threonine-rich activation domain whose transactivation potential differs between mammals and Xenopus. Exchanging the activation domain between the Xenopus and rat LFB1, we produced chimeric transactivators whose activities are primarily determined by the origin of the activation domain. By replacing the serine/threonine-rich activation domain of LFB1 with the acidic activation domain of VP16, we generated transcription factors that act as dominant positive interfering mutants on endogenous LFB1 in differentiated hepatoma cells. As these LFB1/VP16 chimeras show no self-squelching as observed with wild-type LFB1 and increase the activity of saturating LFB1, we postulate that acidic and serine/threonine-rich activation domains use different targets of the basal transcription machinery. Stable transfection of various LFB1 derivatives, including those containing the VP16 transactivation domain, into the dedifferentiated C2 hepatoma cell resulted in cell clones stably expressing LFB1 function. However, as in none of these clones the chromosomal albumin genes are activated, we conclude that the presence of functional LFB1 may not be sufficient to reactivate liver-specific functions lost in dedifferentiated hepatoma cells.

The transcription factor LFB1 (HNF1) was initially identified as a regulator of liver-specific gene expression in mammals. It interacts with the promoter element HP1, which is functionally conserved between mammals and amphibians, suggesting that a homologous factor, XLFB1, also exists in Xenopus laevis. To study the role of LFB1 in early development, we isolated two groups of cDNAs coding for this factor from a Xenopus liver cDNA library by using a rat LFB1 cDNA probe. A comparison of the primary structures of the Xenopus and mammalian proteins shows that the myosin-like dimerization helix, the POU-A-related domain, the homeo-domain-related region, and the serine/threonine-rich activation domain are conserved between X. laevis and mammals, suggesting that all these features typical for LFB1 are essential for function. Using monoclonal antibodies, we demonstrate that XLFB1 is present not only in the liver but also in the stomach, intestine, colon, and kidney. In an analysis of the expression of XLFB1 in the developing Xenopus embryo, XLFB1 transcripts appear at the gastrula stage. The XLFB1 protein can be identified in regions of the embryo in which the liver diverticulum, stomach, gut, and pronephros are localized. The early appearance of XLFB1 expression during embryogenesis suggests that the tissue-specific transcription factor XLFB1 is involved in the determination and/or differentiation of specific cell types during organogenesis.

The electronic structures of SmScO{sub 3}, GdScO{sub 3}, and DyScO{sub 3} are investigated by means of x-ray photoelectron spectroscopy, x-ray emission spectroscopy (XES), and x-ray absorption spectroscopy (XAS). A strong hybridization between Sc 3d and O 2p is found, and a contribution of the rare-earth 5d states to this hybridization is not excluded. The band gaps of the compounds are determined by combining XES and XAS measurements. For SmScO{sub 3}, GdScO{sub 3}, and DyScO{sub 3} the band gaps were determined to be 5.6, 5.8, and 5.9 eV, respectively. Magnetization versus temperature measurements reveal antiferromagnetic coupling at 2.96 (SmScO{sub 3}), 2.61 (GdScO{sub 3}), and 3.10 K (DyScO{sub 3}). For DyScO{sub 3} a Rietveld refinement of a 2 K neutron-diffraction data set gives the spin arrangement of Dy in the Pbnm structure (Shubnikov group: Pb{sup '}n{sup '}m{sup '})

The electronic structures of iron oxide and iron disulfide (FeO and $\mathrm{Fe}{\mathrm{S}}_{2}$) have been examined using x-ray emission spectroscopy and other core-level spectroscopies. We compare the excitation spectra for charge neutral excitation (x-ray emission) and ionization (photoelectron spectroscopy) at the $2p$ edge and with final-state $3s$ holes. At the Fe ${L}_{2}$-edge, the branching ratio of $L\ensuremath{\beta}$ to $L\ensuremath{\alpha}$ emission is much higher for high spin FeO than for low spin $\mathrm{Fe}{\mathrm{S}}_{2}$, similar to previous observations of Heusler alloys. We suggest that there is a general trend toward high branching ratios for magnetic $3d$ materials and low branching ratios for nonmagnetic materials. Resonant inelastic x-ray spectra of FeO with $3s$ final-state holes show a smaller exchange splitting than the corresponding x-ray photoemission spectroscopy spectra with $3s$ hole states.

Experimental studies of x-ray photoelectron and Co Lalpha x-ray emission spectra of the ZnS:Co semiconductor were carried out. It was established that Co ions are present in isovalent Co2+ configuration and that the Co 3d impurity states are localized above the top of the valence band by 1.0 +/- 0.2 eV.

We present Mn $3s$ x-ray photoelectron spectra of manganese oxides with the Mn formal valency from $2+$ to $4+.$ We found that the ${\mathrm{Sr}}^{2+}$ doping or cation deficiency in manganites do not change the Mn $3s$ splitting in manganites with the Mn formal valency from $3.0+$ to $3.3+.$ We suggest that doping holes are localized in O $2p$ states.

We review the data available on the structure, developmental appearance and embryonic regulation of the tissue-specific transcription factor HNF1 alpha (LFB1) in Xenopus. The expression of the HNF1 alpha gene starts early in embryogenesis shortly after mid-blastula transition and the protein accumulates in the region of the embryo where liver, pronephros and gut--tissues that contain HNF1 alpha in the adult--are developing. The cofactor DCoH, known to stabilize dimer formation of HNF1 alpha, is present as a maternal factor in the egg and has a partially distinct tissue distribution compared to HNF1 alpha. This implies that DCoH does not only modulate HNF1 alpha dimerization but may also cooperate with other transcription factors. By injecting HNF1 alpha promoter CAT constructs into fertilized Xenopus eggs we obtained activation of the injected gene restricted to the region of the developing larvae expressing endogenous HNF1 alpha. Deletion analysis allowed to define the OZ-element that is essential for embryonic activation. This element also occurs in other promoters activated at mid-blastula transition in the embryo and interacts with the maternal factor OZ-1. As the HNF1 alpha promoter also contains functional binding sites for HNF4 and HNF1, we postulate that all of these transcription factors contribute to the cascade leading to proper embryonic activation of the HNF1 alpha gene.

Specimens of 38 melanomas of the oral cavity and facial skin and 23 lymph nodes with melanoma metastases were stained immunohistochemically for the presence of variants 5, 6, 7 and 8 of CD-44 antigen. A positive reaction was observed only for variant 7-8 in primary melanomas as well as in lymph nodes with metastases from melanoma. The CD-44 score (percentage of CD-44 positive cells chi intensity of reaction) correlated with metastatic behaviour of tumours and was greater in metastatic lymph nodes than in primary tumours.

The transcription factor LFB1 (HNF1) involved in the expression of liver-specific genes is characterized by a serine/threonine-rich activation domain whose transactivation potential differs between mammals and Xenopus. Exchanging the activation domain between the Xenopus and rat LFB1, we produced chimeric transactivators whose activities are primarily determined by the origin of the activation domain. By replacing the serine/threonine-rich activation domain of LFB1 with the acidic activation domain of VP16, we generated transcription factors that act as dominant positive interfering mutants on endogenous LFB1 in differentiated hepatoma cells. As these LFB1/VP16 chimeras show no self-squelching as observed with wild-type LFB1 and increase the activity of saturating LFB1, we postulate that acidic and serine/threonine-rich activation domains use different targets of the basal transcription machinery. Stable transfection of various LFB1 derivatives, including those containing the VP16 transactivation domain, into the dedifferentiated C2 hepatoma cell resulted in cell clones stably expressing LFB1 function. However, as in none of these clones the chromosomal albumin genes are activated, we conclude that the presence of functional LFB1 may not be sufficient to reactivate liver-specific functions lost in dedifferentiated hepatoma cells.

On the basis of a study carried out in three teaching departments of maxillofacial surgery the effect was analysed of Solcoseryl dental adherent paste and Linomag in the treatment of acute radiation-induced stomatitis. Both drugs were effective but Solcoseryl was superior to the other drug since it accelerated healing by about 50% and formed a protecting dressing on the inflamed mucosa.

After a study in three maxillofacial surgery teaching hospital departments the authors evaluated the usefulness of Solcoseryl dental adhesive paste as compared to Apernyl in the treatment of postextraction alveolitis. Solcoseryl paste was found to shorten the healing period by about 50% in comparison with Apernyl.

Observations of the incidence of MT from distant organs and tissues to the maxillofacial region are presented on the basis of 13 cases (3.2% of the total number of patients with malignant tumors). Metastatic carcinomas are most frequently found in the mandible (61.5%). The primary locus is usually the breast, kidney, bronchus, or thyroid gland (61.5%), the diagnosis of metastasis aided in localization of the primary tumor. Successful results of radical treatment were obtained in only two cases; they survived for three and 11 years. The other 11 patients died within two months to a year. The function of maxillofacial surgeons in discovering primary and metastatic tumors of the jaws and face is emphasized.