Randomised, quadruple blinded, placebo controlled, multicentre trial investigating prophylactic tamsulosin in prevention of postoperative urinary retention in men after endoscopic total extraperitoneal inguinal hernia repair (STOP-POUR trial): a study protocol.

INTRODUCTION: Postoperative urinary retention (POUR) is a common complication after inguinal hernia repair with a reported incidence up to 34%. It can be described as the inability to initiate urination or insufficient bladder emptying following surgery. It usually requires the use of catheterisation to empty the bladder in order to prevent further injury to the bladder or kidneys and to relief from pain. Tamsulosin is a medication that is commonly used in men with urinary symptoms related to an enlarged prostate. There is some evidence to suggest that it may also potentially be beneficial for preventing POUR. METHODS AND ANALYSIS: This is a multicentre, blinded, prospective, phase IV randomised controlled trial with parallel allocation. Six hundred and thirty-four patients scheduled for elective endoscopic inguinal hernia repair surgery will be recruited. There will be effective (concealed) randomisation of the subjects to the intervention/control groups. Group assignment will be performed using a covariate-adaptive allocation procedure to provide a balance for selected covariates. The interventional group receives 0.4 mg tamsulosin hydrochloride and the control-group receives one placebo capsule matching the active study drug, both daily, starting from 5 days prior to the day of surgery, at the day of surgery and for 1 day following surgery. The primary outcome is any need for urinary catheterisation postoperatively as a binary outcome. Secondary outcome measures include postoperative pain, change in International Prostate Symptom Score from baseline prior to surgery to after surgery and hospital stay. ETHICS AND DISSEMINATION: The study has been approved by the Northwestern and Central Switzerland Ethics Committee (2020-00569) and it is being conducted in accordance with the Declaration of Helsinki and Good Clinical Practice. Study results will be disseminated through peer-reviewed journals and national and international scientific conferences. TRIAL REGISTRATION NUMBERS: SNCTP000003904. NCT04491526.

Two-dimensional polymer formation on surfaces: insight into the roles of precursor mobility and reactivity.

We report on a combined scanning tunneling microscopy (STM), X-ray photoelectron spectroscopy (XPS), and density functional theory (DFT) study on the surface-assisted assembly of the hexaiodo-substituted macrocycle cyclohexa-m-phenylene (CHP) toward covalently bonded polyphenylene networks on Cu(111), Au(111), and Ag(111) surfaces. STM and XPS indicate room temperature dehalogenation of CHP on either surface, leading to surface-stabilized CHP radicals (CHPRs) and coadsorbed iodine. Subsequent covalent intermolecular bond formation between CHPRs is thermally activated and is found to proceed at different temperatures on the three coinage metals. The resulting polyphenylene networks differ significantly in morphology on the three substrates: On Cu, the networks are dominated by "open" branched structures, on the Au surface a mixture of branched and small domains of compact network clusters are observed, and highly ordered and dense polyphenylene networks form on the Ag surface. Ab initio DFT calculations allow one to elucidate the diffusion and coupling mechanisms of CHPRs on the Cu(111) and Ag(111) surfaces. On Cu, the energy barrier for diffusion is significantly higher than the one for covalent intermolecular bond formation, whereas on Ag the reverse relation holds. By using a Monte Carlo simulation, we show that different balances between diffusion and intermolecular coupling determine the observed branched and compact polyphenylene networks on the Cu and Ag surface, respectively, demonstrating that the choice of the substrate plays a crucial role in the formation of two-dimensional polymers.

Atomically precise bottom-up fabrication of graphene nanoribbons.

Graphene nanoribbons-narrow and straight-edged stripes of graphene, or single-layer graphite-are predicted to exhibit electronic properties that make them attractive for the fabrication of nanoscale electronic devices. In particular, although the two-dimensional parent material graphene exhibits semimetallic behaviour, quantum confinement and edge effects should render all graphene nanoribbons with widths smaller than 10 nm semiconducting. But exploring the potential of graphene nanoribbons is hampered by their limited availability: although they have been made using chemical, sonochemical and lithographic methods as well as through the unzipping of carbon nanotubes, the reliable production of graphene nanoribbons smaller than 10 nm with chemical precision remains a significant challenge. Here we report a simple method for the production of atomically precise graphene nanoribbons of different topologies and widths, which uses surface-assisted coupling of molecular precursors into linear polyphenylenes and their subsequent cyclodehydrogenation. The topology, width and edge periphery of the graphene nanoribbon products are defined by the structure of the precursor monomers, which can be designed to give access to a wide range of different graphene nanoribbons. We expect that our bottom-up approach to the atomically precise fabrication of graphene nanoribbons will finally enable detailed experimental investigations of the properties of this exciting class of materials. It should even provide a route to graphene nanoribbon structures with engineered chemical and electronic properties, including the theoretically predicted intraribbon quantum dots, superlattice structures and magnetic devices based on specific graphene nanoribbon edge states.

Porous graphenes: two-dimensional polymer synthesis with atomic precision.

We demonstrate, by surface-assisted coupling of specifically designed molecular building blocks, the fabrication of regular two-dimensional polyphenylene networks with single-atom wide pores and sub-nanometer periodicity.

Enantiodiscrimination between an N-acetyl-L-cysteine SAM and proline: an in situ spectroscopic and computational study.

A combination of attenuated total reflection infrared (ATR-IR) and modulation excitation spectroscopy (MES) is used to study the enantiodiscriminating interactions between proline and a chiral, self-assembled monolayer (SAM) of N-acetyl-L-cysteine on gold. The N-acetyl-L-cysteine SAM consists of a mixture of protonated and deprotonated molecules. Whereas both species are influenced by adsorbed proline, only the deprotonated molecules are involved in enantiodiscrimination. Density functional theory (DFT) calculations reveal that electrostatics dominates the interaction between the two molecules. By modulating the absolute configuration of proline over the chiral SAM, and a subsequent phase-sensitive detection of the periodically varying signals in the ATR-IR spectra, the small spectral differences between the diastereomeric complexes are spotted. The resulting difference spectrum is in qualitative agreement with the spectrum predicted by the DFT calculations.

Adsorption kinetics of L-glutathione on gold and structural changes during self-assembly: an in situ ATR-IR and QCM study.

The adsorption of L-glutathione (gamma-Glu-Cys-Gly) from ethanol on gold surfaces was studied in situ by both attenuated total reflection infrared (ATR-IR) spectroscopy and using a quartz crystal microbalance (QCM). The molecule is firmly anchored to the gold surface through the thiol group. Different IR signals of adsorbed L-glutathione, notably the amide I and nu(-COOH), show significantly different behavior with time, which reveals that their increase is not related to adsorption (mass uptake) alone. This indicates that structural transformations take place during the formation of the self-assembled monolayer (SAM). In particular, the intensity of the acid signal increases quickly only within the first couple of minutes. The complexity of the self-assembling process is confirmed by QCM measurements, which show fast mass uptake within about 100 s followed by a considerably slower regime. The structural change superimposed on the mass uptake is, based on the in situ time-resolved ATR-IR measurements, assigned to the interaction of the acid group of the Gly moiety with the surface. The latter group is protonated in ethanol but deprotonates upon interaction with the gold surface. The protonation-deprotonation equilibrium is sensitive to external stimuli, such as the presence of dissolved L-glutathione molecules. The interaction of the acid group with the surface and concomitant deprotonation proceeds via two distinguishable steps, the first being a reorientation of the molecule, followed by the deprotonation.

L-glutathione chemisorption on gold and acid/base induced structural changes: a PM-IRRAS and time-resolved in situ ATR-IR spectroscopic study.

Adsorption of the tripeptide L-glutathione (gamma-glu-cys-gly) on gold surfaces was investigated by polarization modulation infrared reflection absorption spectroscopy (PM-IRRAS) and attenuated total reflection (ATR) infrared spectroscopy. PM-IRRAS was used to study ex situ the adsorbate layer prepared from aqueous solutions at different pH, whereas ATR-IR was applied to study in situ adsorption from ethanol in the presence and absence of acid and base. ATR-IR was furthermore combined with modulation spectroscopy in order to investigate the reversible changes within the adsorbate layer induced by acid and base stimuli, respectively. The molecule is firmly anchored on the gold surface via the thiol group of the cys part. However, the ATR-IR spectra in ethanol indicate a further interaction with the gold surface via the carboxylic acid group of the gly part of the molecule, which deprotonates upon adsorption. Hydrochloric acid readily protonates the two acid groups of the adsorbed molecule. During subsequent ethanol flow the acid groups deprotonate again, a process which proceeds in two distinct steps: a fast step associated with the deprotonation of the acid in the glu part of the molecule and a considerably slower step associated with deprotonation of the acid in the gly moiety. The latter process is assisted by the interaction of the corresponding acid group with the surface. The spectra furthermore indicate a rearrangement of the hydrogen bonding network within the adsorbate layer upon deprotonation. Depending on the protonation state during adsorption of l-glutathione, the response toward identical protonation-deprotonation stimuli is significantly different. This is explained by the ionic state-dependent shape of the molecule, as supported by density functional theory calculations. The different shapes of the individual molecules during layer formation thus influence the structure of the adsorbate layer.

Probing enantiospecific interactions between proline and an l-glutathione self-assembled monolayer by modulation excitation ATR-IR spectroscopy.

The interaction of proline with self-assembled monolayers (SAMs) of l-glutathione (gamma-glu-cys-gly) on gold was investigated by a combination of attenuated total reflection (ATR-IR) infrared and modulation excitation spectroscopy (MES). The latter technique makes use of phase-sensitive detection of periodically varying signals and allows discrimination between species with different kinetics such as dissolved proline and adsorbed molecules. By applying a convection-diffusion model coupled to adsorption and desorption, it was possible to extract relative adsorption and desorption rates from the experimental data for the two enantiomers of proline, fully accounting for mass transport within the flow-through cell. The results show that, in particular, the desorption kinetics is different for the two enantiomers. Therefore, the l-glutathione SAM can discriminate between enantiomers, d-proline being stronger bound. The IR spectra reveal that upon interaction with proline the adsorbed l-glutathione is protonated at the gly part of the molecule, which, in the absence of proline, is bound to the gold surface as carboxylate. The observed protonation of adsorbed l-glutathione upon interaction with proline goes along with a structural change of the former, which seems to play an important role for enantiodiscrimination.

Adsorption kinetics, orientation, and self-assembling of N-acetyl-L-cysteine on gold: a combined ATR-IR, PM-IRRAS, and QCM study.

The adsorption of N-acetyl-L-cysteine from ethanol solution on gold has been studied by in situ attenuated total reflection infrared (ATR-IR) spectroscopy, polarization modulation infrared reflection absorption spectroscopy, and a quartz crystal microbalance. After an initial fast adsorption, in situ ATR-IR revealed two considerably slower processes, besides further adsorption. The appearance of carboxylate bands and the partial disappearance of the carboxylic acid bands demonstrated that part of the molecules on the surface underwent deprotonation. In addition, the C=O stretching vibration of the carboxylic acid group shifted to lower and the amide II band to higher wavenumbers, indicating hydrogen-bonding interactions within the adsorbate layer. Based on the initial ATR-IR spectrum, which did not reveal deprotonation, the orientation of the molecule within the adsorbate layer was determined. For this, density functional theory was used to calculate the transition dipole moment vectors of the vibrational modes of N-acetyl-l-cysteine. The projections of the latter onto the z-axis of the fixed surface coordinate system were used to determine relative band intensities for different orientations of the molecule. The analysis revealed that the amide group is tilted with respect to and points away from the surface, whereas the carboxylic acid is in proximity to the surface, which is also supported by a shift of the C-O-H bending mode. This position of the acid group favors its deprotonation assisted by the gold surface and easily enables intermolecular interactions. Periodic acid stimuli revealed reversible protonation/deprotonation of part of the adsorbed molecules. However, only non-hydrogen-bonded carboxylic acid groups showed a response toward the acid stimuli.