The formation and reductive desorption of self-assembled monolayers of 6-mercaptohexanol on mercury has been studied by using cathodic stripping voltammetry and capacitative transients, including the possibility of expanding or contracting the electrode area at the end of the preconcentration step. Experimental evidence shows the existence of three sequential stages during the formation of a thiol self-assembled monolayer. Each of these stages can be associated to the presence of (i) a low surface density state of oxidized thiol molecules, characterized by a single electrodimerization wave, (ii) a high surface density state, characterized by the emergence of a second voltammetric wave, and (iii) an ordered monolayer, which gives rise to a voltammetric spike. On the basis of electrode expansion experiments, a method is described to determine the surface concentrations of oxidized products, which does not require a baseline subtraction of the voltammograms to account for the nonfaradaic current. Quantitative voltammetric fits are consistent with the initial formation of a mixture of noninteracting monomers and dimers of oxidized thiol. The value of the maximum surface concentration and the ability to block the Ru(NH 3 ) 6 3+ electron transfer reveal that oxidized thiol molecules adopt a nearly perpendicular orientation in the high surface density state, which hampers ionic permeation. A theoretical model is proposed to account for the observed voltammetric behavior. The transition from the lower to the higher surface density states is modeled as a chemical step involving the exchange of metal free sites. Capacitative transients are also interpreted in terms of the three-stages model.

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Iodoalkynes [1,benzene (p-BIB) and 1,3-bis(iodoethynyl)benzene (m-BIB)] have been used successfully to prepare halogen bonding complexes with a range of 4-pyridine derivatives showing liquid crystalline organizations. The trimeric halogen-bonded complexes obtained from p-BIB have a rod-like structure and exhibited high order calamitic phases (SmB and G). In contrast, m-BIB gives rise to bent-shaped structures that display SmAP-like mesophases. Furthermore it was found that the presence of three and five aromatic rings in these halogen-bonding complexes promotes calamitic mesophases while seven rings are required to stabilize bent-core mesophases. The formation of halogen bonding in the complexes was confirmed by several techniques, including FT-IR, XPS, and single crystal X-ray diffraction and the strength of the bonds was evaluated by DFT calculations

BackgroundThe aim of this study was to analyze the mortality and predictors of 30-day mortality among hospitalized patients with Pseudomonas aeruginosa urinary tract infection (PAUTI) and the impact of antibiotic treatment on survival.MethodsPatients admitted to our hospital with PAUTI or those diagnosed of PAUTI during hospitalization for other disease between September 2012 and September 2014 were included. Repeated episodes from the same patient were excluded. Database with demographic, clinical and laboratory ítems was created. Empirical and definitive antibiotic therapy, antimicrobial resistance and all-cause mortality at 30 and 90 days were included.Results62 patients were included, with a mean age of 75 years. 51% were male. Mortality was 17.7% at 30 days and 33.9% at 90 days. Factors associated with reduced survival at 30 days were chronic liver disease with portal hypertension (P<0,01), diabetes mellitus (P = 0,04) chronic renal failure (P = 0,02), severe sepsis or septic shock (P<0,01), Charlson index > 3 (P = 0.02) and inadequated definitive antibiotic treatment (P<0,01). Independent risk factors for mortality in multivariate analysis were advanced chronic liver disease (HR 77,4; P<0,01), diabetes mellitus (HR 3,6; P = 0,04), chronic renal failure (HR 4,1; P = 0,03) and inadequated definitive antimicrobial treatment (HR 6,8; P = 0,01).ConclusionsPAUTI are associated with high mortality in hospitalized patients, which increases significantly in those with severe comorbidity such as chronic renal failure, advanced liver disease or diabetes mellitus. Inadequated antibiotic treatment is associated with poor outcome, which remarks the importance of adjusting empirical antibiotic treatment based on the microbiological susceptibility results.

Ultraviolet photoelectron spectroscopy ͑UPS͒, thermal desorption mass spectroscopy ͑TDS͒, and first-principles density functional ͑DF͒ generalized-gradient-corrected calculations were used to study the adsorption of CO and NO on MgO͑100͒, Ni 0.06 Mg 0.94 O͑100͒, and Cr 0.07 Mg 0.93 O͑100͒ surfaces. UPS spectra and DF calculations show clear differences in the electronic properties of these oxides. After doping MgO with nickel, states with Ni 3d character appear ϳ1.5 eV above the occupied ͕O 2pϩMg 3s͖ band. A similar phenomenon is found after adding Cr, but now the dopant levels are ϳ3 eV above the ͕O 2pϩMg 3s͖ band. In CO-and NO-TDS experiments, the reactivity of the oxide surfaces increases in the sequence: MgO͑100͒ϽNi 0.06 Mg 0.94 O͑100͒ ϽCr 0.07 Mg 0.93 O͑100͒. Cr-bonded molecules exhibit adsorption energies as large as 15 ͑CO͒ and 20 kcal/mol ͑NO͒. For CO and NO on MgO͑100͒, the mixing between the frontier orbitals of the adsorbate and the bands of the surface is poor, and the low adsorption energy is mainly due to weak MgO↔CO or MgO↔NO electrostatic interactions. On the other hand, the Cr 3d levels in Cr 0.07 Mg 0.93 O͑100͒ are energetically well positioned for responding to the presence of adsorbates, leading to substantial binding of CO and NO. DF results for a series of TM 0.06 Mg 0.94 O͑100͒ systems (TMϭZn, Ni, Fe, or Cr͒ show a correlation between their electronic and chemical properties: the less stable the occupied levels of a mixed-metal oxide, the higher its chemical reactivity. An important parameter to consider when designing a mixed-metal oxide catalyst is the final energy position of the occupied states provided by the second metal or dopant agent.

Summary Background 80% of individuals with cancer will require a surgical procedure, yet little comparative data exist on early outcomes in low-income and middle-income countries (LMICs). We compared postoperative outcomes in breast, colorectal, and gastric cancer surgery in hospitals worldwide, focusing on the effect of disease stage and complications on postoperative mortality. Methods This was a multicentre, international prospective cohort study of consecutive adult patients undergoing surgery for primary breast, colorectal, or gastric cancer requiring a skin incision done under general or neuraxial anaesthesia. The primary outcome was death or major complication within 30 days of surgery. Multilevel logistic regression determined relationships within three-level nested models of patients within hospitals and countries. Hospital-level infrastructure effects were explored with three-way mediation analyses. This study was registered with ClinicalTrials.gov , NCT03471494 . Findings Between April 1, 2018, and Jan 31, 2019, we enrolled 15 958 patients from 428 hospitals in 82 countries (high income 9106 patients, 31 countries; upper-middle income 2721 patients, 23 countries; or lower-middle income 4131 patients, 28 countries). Patients in LMICs presented with more advanced disease compared with patients in high-income countries. 30-day mortality was higher for gastric cancer in low-income or lower-middle-income countries (adjusted odds ratio 3·72, 95% CI 1·70–8·16) and for colorectal cancer in low-income or lower-middle-income countries (4·59, 2·39–8·80) and upper-middle-income countries (2·06, 1·11–3·83). No difference in 30-day mortality was seen in breast cancer. The proportion of patients who died after a major complication was greatest in low-income or lower-middle-income countries (6·15, 3·26–11·59) and upper-middle-income countries (3·89, 2·08–7·29). Postoperative death after complications was partly explained by patient factors (60%) and partly by hospital or country (40%). The absence of consistently available postoperative care facilities was associated with seven to 10 more deaths per 100 major complications in LMICs. Cancer stage alone explained little of the early variation in mortality or postoperative complications. Interpretation Higher levels of mortality after cancer surgery in LMICs was not fully explained by later presentation of disease. The capacity to rescue patients from surgical complications is a tangible opportunity for meaningful intervention. Early death after cancer surgery might be reduced by policies focusing on strengthening perioperative care systems to detect and intervene in common complications. Funding National Institute for Health Research Global Health Research Unit.

Synchrotron-based high-resolution photoemission, x-ray absorption near-edge spectroscopy, and first-principles density-functional calculations are used to examine the interaction of SO2 with pure and modified surfaces of magnesium oxide. On a MgO(100) single crystal, SO2 reacts with O centers to form SO3 and SO4 species. The bonding interactions with the Mg cations are weak and do not lead to cleavage of S–O bonds. An identical result is found after adsorbing SO2 on pure stoichiometric powders of MgO and other oxides (TiO2, Cr2O3, Fe2O3, NiO, CuO, ZnO, V2O5, CeO2, BaO). In these systems, the occupied cations bands are too stable for effective bonding interactions with the LUMO of SO2. To activate an oxide for S–O bond cleavage, one has to create occupied metal states above the valence band of the oxide. DF calculations predict that in the presence of these “extra” electronic states the adsorption energy of SO2 should increase, and there should be a significant oxide→SO2(LUMO) charge transfer that facilitates the cleavage of the S–O bonds. In this article, we explore three different approaches (formation of O vacancies, promotion with alkali metals, and doping with transition metals) that lead to the activation of SO2 and S–O bond breaking on MgO and oxides in general. Basic principles for a rational design of catalysts with a high efficiency for the destruction of SO2 are presented.

The interaction of CH3SH with TiO2(110) has been studied with a combination of synchrotron-based high-resolution photoemission, thermal desorption mass spectroscopy, and first-principles density functional slab calculations. On the Ti and O sites of a perfect TiO2(110) substrate there is no dissociation of CH3SH. The molecule bonds to Ti sites via its S lone pairs and desorbs at temperatures below 300 K. For CH3SH chemisorbed on terraces of TiO2(110), the desorption energies for molecular adsorption are ∼10−13 kcal/mol. The desorption energy for CH3SH on defects is ∼18 kcal/mol. Photoemission results show that the active sites for the decomposition of CH3SH are associated with oxygen vacancies (“Tiδ+” sites, δ ≤ 3). These defects induce occupied electronic states above the valence band of stoichiometric TiO2 that bond well CH3S, S, and C. Thus, the presence of O vacancies in the oxide surface allows the cleavage of the S−H bond in methanethiol and the deposition of CH3S. The bond between CH3S and O-vacancy sites is mainly covalent, but the bonding interactions are very strong and can induce the migration of O vacancies from the bulk to the surface of the oxide. In systems with a limited number of O vacancies, adsorbed CH3S and H recombine and desorb as CH3SH into gas phase. For surfaces with a large concentration of O vacancies and defects, the C−S bond in adsorbed CH3S breaks in the 250−750 K temperature range with CH3 or CH4 desorbing into gas phase and leaving S and CH x fragments on the surface. These results illustrate the important role played by O vacancies in the chemistry of a thiol over an oxide surface.