Quantitative Characterization of a Desalination Membrane Model System by X-ray Photoelectron Spectroscopy.

Aromatic polyamide films form the active layer in reverse osmosis desalination membranes. Despite widespread use of this technology, it suffers from low rejection rates for certain water contaminants and from membrane fouling. Through a better understanding of the fundamental surface chemical processes during reverse osmosis desalination, advances in membrane and material design are expected. The recent invention of a molecular layer-by-layer (mLbL) preparation technique [ Johnson , P. M. ; Molecular Layer-by-Layer Deposition of Highly Crosslinked Polyamide Films . J. Polym. Sci., Part B: Polym. Phys. 2012 , 50 ( 3 ), 168 - 173 ] yields films that are sufficiently smooth to warrant investigation with high-resolution microscopy and spectroscopy methods. We present high-resolution, quantitative X-ray photoelectron spectroscopy (XPS) data on the surface chemistry of ultrathin polyamide films that can serve as a model system for desalination membranes. We show that a quantitative analysis of the XPS spectra gives information about the functional groups of the film as well as other compounds present due to the synthesis under ambient conditions. Unpolymerized functional groups are identified and aid in understanding the degree of cross-linking. Investigation of polymers with synchrotron-based XPS requires taking beam-induced changes into account. We quantify X-ray beam damage and show that beam damage to the polyamide is limited, allowing long-term investigation of thin polyamide films. Characterizing mLbL-grown films via high-resolution XPS is the basis for a better understanding of the chemical interplay of polyamide surface functional groups with the major components of desalination systems.

Recurrence rate of odontogenic keratocyst treated by enucleation and peripheral ostectomy: Retrospective case series with up to 12 years of follow-up

BACKGROUND: Odontogenic keratocysts have been reported with high recurrence rates in the literature so various treatment modalities from simple enucleation to resection have been performed to achieve the cure. The purpose of this retrospective study was to investigate the recurrence rate of odontogenic keratocysts (OKCs) treated by enucleation and peripheral ostectomy. MATERIAL AND METHODS: An electronic search of the database of the Hacettepe University, Faculty of Medicine, Department of Pathology, was undertaken to identify patients histologically diagnosed with OKCs treated at Department of Oral and Maxillofacial Surgery between 2001 and 2015. RESULTS: In total, 81 patients were studied. The mean age at the time of diagnosis was 42 years, and the male:female ratio was 1:0.7. OKCs were located primarily in the posterior mandibular region (41%). Twenty-seven patients were re-examined to determine the recurrence rate. The mean follow-up period was 5 years (range, 1-12 years). The recurrence rate was 14.8%. The relationship between location of the lesion and recurrence was not statistically significant (p= 0.559). There was also no statistically significant relation between the recurrence rate and treatment option of teeth involved in the lesion (p= 0.579). CONCLUSIONS: The authors conclude that treatment of OKCs by enucleation with peripheral ostectomy is associated with minimal morbidity and is preferred over other aggressive treatment modalities. Meticulous radiographic examination and careful surgical resection may decrease the recurrence rate of OKCs

Dimethyl methylphosphonate adsorption and decomposition on MoO2 as studied by ambient pressure x-ray photoelectron spectroscopy and DFT calculations.

Organophosphonates range in their toxicity and are used as pesticides, herbicides, and chemical warfare agents (CWAs). Few laboratories are equipped to handle the most toxic molecules, thus simulants such as dimethyl methylphosphonate (DMMP), are used as a first step in studying adsorption and reactivity on materials. Benchmarked by combined experimental and theoretical studies of simulants, calculations offer an opportunity to understand how molecular interactions with a surface changes upon using a CWA. However, most calculations of DMMP and CWAs on surfaces are limited to adsorption studies on clusters of atoms, which may differ markedly from the behavior on bulk solid-state materials with extended surfaces. We have benchmarked our solid-state periodic calculations of DMMP adsorption and reactivity on MoO2 with ambient pressure x-ray photoelectron spectroscopy studies (APXPS). DMMP is found to interact strongly with a MoO2 film, a model system for the MoO x component in the ASZM-TEDA© gas filtration material. Density functional theory modeling of several adsorption and decomposition mechanisms assist the assignment of APXPS peaks. Our results show that some of the adsorbed DMMP decomposes, with all the products remaining on the surface. The rigorous calculations benchmarked with experiments pave a path to reliable and predictive theoretical studies of CWA interactions with surfaces.

Water Adsorption and Dissociation on Polycrystalline Copper Oxides: Effects of Environmental Contamination and Experimental Protocol.

We use ambient-pressure X-ray photoelectron spectroscopy (APXPS) to study chemical changes, including hydroxylation and water adsorption, at copper oxide surfaces from ultrahigh vacuum to ambient relative humidities of ∼5%. Polycrystalline CuO and Cu2O surfaces were prepared by selective oxidation of metallic copper foils. For both oxides, hydroxylation occurs readily, even at high-vacuum conditions. Hydroxylation on both oxides plateaus near ∼0.01% relative humidity (RH) at a coverage of ∼1 monolayer. In contrast to previous studies, neither oxide shows significant accumulation of molecular water; rather, both surfaces show a high affinity for adventitious carbon contaminants. Results of isobaric and isothermic experiments are compared, and the strengths and potential drawbacks of each method are discussed. We also provide critical evaluations of the effects of the hot filament of the ion pressure gauge on the reactivity of gas-phase species, the peak fitting procedure on the quantitative analysis of spectra, and rigorous accounting of carbon contamination on data analysis and interpretation. This work underscores the importance of considering experimental design and data analysis protocols during APXPS experiments with water vapor in order to minimize misinterpretations arising from these factors.

Alcohol-Dependent Subjects Show Different Personality Traits Compared With Subjects With Multiple Substance Dependence: Preliminary Data.

METHODS: We compared personality traits of 27 persons with multiple substance dependence with personality data of 52 alcohol-dependent persons regarding their personality traits and disorders (obtained by using SCID-II, TCI and NEO FFI). Both patient groups were free of any other mental disorder. RESULTS: In SKD-II, we found significant differences in the male group in dependent and scizotypic personality disorder. There were no significant differences in the female group, but sample was very small. We also found significant differences between alcohol-dependent and multiple substance-dependent persons in extraversion and novelty seeking. CONCLUSIONS: We detected significant differences in personality disorders evaluated by SCID-II. Temperament and character items­as evaluated by NEO FFI and TCI­showed also significant differences in personality traits. Given the limited number of subjects, the data should be regarded as preliminary until replicated in a larger sample. Nevertheless, the findings may be of clinical relevance with respect to prognosis or individualized treatment. These findings should be treated with caution until replicated.