One-step functionalization of mildly and strongly reduced graphene oxide with maleimide: an experimental and theoretical investigation of the Diels-Alder [4+2] cycloaddition reaction.

For large-scale graphene applications, such as the production of polymer-graphene nanocomposites, exfoliated graphene oxide (GO) and its reduced form (rGO) are presently considered to be very suitable starting materials, showing enhanced chemical reactivity with respect to pristine graphene, in addition to suitable electronic properties (i.e., tunable band gap). Among other chemical processes, a suitable way to obtain surface decoration of graphene is through a direct one-step Diels-Alder (DA) reaction, e.g. through the use of dienophile or diene moieties. However, the feasibility and extent of decoration largely depends on the specific graphene microstructure that in the case of rGO sheets is not easy to control and generally presents a high degree of inhomogeneity owing to various on-plane functionalization (e.g., epoxide and hydroxyl groups) or in-plane lattice defects. In an effort to gain some insights into the covalent functionalization of variably reduced GO samples, we present a combined experimental and theoretical study on the DA cycloaddition reaction of maleimide, a dienophile functional unit well-suited for chemical conjugation of polymers and macromolecules. In particular, we considered both mildly and strongly reduced GOs. Using thermogravimetry, Raman and X-Ray photoelectron spectroscopy, and elemental analysis we show evidence of variable chemical reactivity of rGO as a function of the residual oxygen content. Moreover, from quantum mechanical calculations carried out at the DFT level on different graphene reaction sites, we provide a more detailed molecular view to interpret experimental findings and to assess the reactivity series of different graphene modifications.

EAES rapid guideline: systematic review, network meta-analysis, CINeMA and GRADE assessment, and European consensus on bariatric surgery-extension 2022.

BACKGROUND: The European Association for Endoscopic Surgery Bariatric Guidelines Group identified a gap in bariatric surgery recommendations with a structured, contextualized consideration of multiple bariatric interventions. OBJECTIVE: To provide evidence-informed, transparent and trustworthy recommendations on the use of sleeve gastrectomy, Roux-en-Y gastric bypass, adjustable gastric banding, gastric plication, biliopancreatic diversion with duodenal switch, one anastomosis gastric bypass, and single anastomosis duodeno-ileal bypass with sleeve gastrectomy in patients with severe obesity and metabolic diseases. Only laparoscopic procedures in adults were considered. METHODS: A European interdisciplinary panel including general surgeons, obesity physicians, anesthetists, a psychologist and a patient representative informed outcome importance and minimal important differences. We conducted a systematic review and frequentist fixed and random-effects network meta-analysis of randomized-controlled trials (RCTs) using the graph theory approach for each outcome. We calculated the odds ratio or the (standardized) mean differences with 95% confidence intervals for binary and continuous outcomes, respectively. We assessed the certainty of evidence using the CINeMA and GRADE methodologies. We considered the risk/benefit outcomes within a GRADE evidence to decision framework to arrive at recommendations, which were validated through an anonymous Delphi process of the panel. RESULTS: We identified 43 records reporting on 24 RCTs. Most network information surrounded sleeve gastrectomy and Roux-en-Y gastric bypass. Under consideration of the certainty of the evidence and evidence to decision parameters, we suggest sleeve gastrectomy or laparoscopic Roux-en-Y gastric bypass over adjustable gastric banding, biliopancreatic diversion with duodenal switch and gastric plication for the management of severe obesity and associated metabolic diseases. One anastomosis gastric bypass and single anastomosis duodeno-ileal bypass with sleeve gastrectomy are suggested as alternatives, although evidence on benefits and harms, and specific selection criteria is limited compared to sleeve gastrectomy and Roux-en-Y gastric bypass. The guideline, with recommendations, evidence summaries and decision aids in user friendly formats can also be accessed in MAGICapp:  https://app.magicapp.org/#/guideline/Lpv2kE CONCLUSIONS: This rapid guideline provides evidence-informed, pertinent recommendations on the use of bariatric and metabolic surgery for the management of severe obesity and metabolic diseases. The guideline replaces relevant recommendations published in the EAES Bariatric Guidelines 2020.

Efficient 1400-1600†nm Circularly Polarized Luminescence from a Tuned Chiral Erbium Complex.

Novel chiral Er complexes based on both enantiomers of extended i PrPyBox (2,6-Bis[4-isopropyl-4,5-dihydrooxazol-2-yl)]pyridine) show strong near-infrared circularly polarized luminescence (CPL) within the 1400 to 1600 nm spectral region under 450 nm irradiation. CPL activity in this region, despite being particularly rare, would open the way to potential applications in the domain, e.g., of fiber-optic telecommunications and free-space long-distance optical communications employing circularly polarized light. Moreover, the long wavelength excitation is advantageous for applications in the field of (circularly polarized) microscopy and bioimaging.

Mechanochromic LLDPE Films Doped with NIR Reflective Paliogen Black.

The perylene bisimide derivative Paliogen Black (P-black) is proposed as a new chromogenic probe that shows visible (vis) and near-infrared (NIR) responses after mechanical solicitations of host linear low-density polyethylene (LLDPE) films. P-black is reported to display strong absorption in the vis spectrum and unusual reflective and cooling features in the NIR region. Uniaxial deformation of the 2.5, 5, and 10 wt% P-black/LLDPE films yields a dichroic absorption under polarized light with color variations attributed by the computational analysis to the distinct anisotropic behavior of the transition dipole moments of P-black chromophores. When LLDPE films are deformed, P-black aggregates reduce their size from ≈30-40 µm to ≈5-10 µm that, in turn, causes reflectivity losses of about 30-40% at the maximum elongation. This gives rise to warming of 5-6 °C of the locally oriented film placed in contact with a black substrate under the illumination with an IR lamp for 5 s. These features combined with the high sensitivity of the vis-NIR response toward mechanical solicitations render P-black as a new solution to detect uniaxial deformations of plastic films through both optical and thermal outputs.

Synthesis and Spectroscopic Characterization of Thienopyrazine-Based Fluorophores for Application in Luminescent Solar Concentrators (LSCs).

Organic fluorophores have found broad application as emitters in luminescent solar concentrators (LSCs) for silicon photovoltaics. In particular, the preparation of organic conjugated systems with intense light-harvesting ability, emissions in the deep-red and NIR regions, and large Stokes shift values represent a very challenging undertaking. Here, we report a simple and easy way to prepare three symmetrical donor-acceptor-donor (DAD) organic-emitting materials based on a thienopyrazine core. The central core in the three dyes was modified with the introduction of aromatic substituents, aiming to affect their optical properties. The fluorophores were characterized by spectroscopic studies. In all cases, visible-NIR emissions with large Stokes shifts were found, highlighting these molecules as promising materials for the application in LSCs.

Clinical practice guidelines of the European Association for Endoscopic Surgery (EAES) on bariatric surgery: update 2020 endorsed by IFSO-EC, EASO and ESPCOP.

BACKGROUND: Surgery for obesity and metabolic diseases has been evolved in the light of new scientific evidence, long-term outcomes and accumulated experience. EAES has sponsored an update of previous guidelines on bariatric surgery. METHODS: A multidisciplinary group of bariatric surgeons, obesity physicians, nutritional experts, psychologists, anesthetists and a patient representative comprised the guideline development panel. Development and reporting conformed to GRADE guidelines and AGREE II standards. RESULTS: Systematic review of databases, record selection, data extraction and synthesis, evidence appraisal and evidence-to-decision frameworks were developed for 42 key questions in the domains Indication; Preoperative work-up; Perioperative management; Non-bypass, bypass and one-anastomosis procedures; Revisional surgery; Postoperative care; and Investigational procedures. A total of 36 recommendations and position statements were formed through a modified Delphi procedure. CONCLUSION: This document summarizes the latest evidence on bariatric surgery through state-of-the art guideline development, aiming to facilitate evidence-based clinical decisions.

Mechanochromic Fluorescent Polymers with Aggregation-Induced Emission Features.

Mechanochromic polymers are defined as materials that are able to detect a mechanical stress through an optical output. This feature has evoked a growing interest in the last decades, thanks to the progress of chromogenic molecules whose optical characteristics and chemical functionalities allow their effective insertion in many thermoplastic and thermoset matrices. Among the different types of fluorogenic probes able to detect mechanical solicitations, those with aggregation-induced emission (i.e., AIEgens) have attracted tremendous interest since their discovery in 2001. In the present review, the main principles behind the AIEgens working behavior are introduced along with the current state of knowledge concerning the design and preparation of the derived mechanochromic fluorescent polymers. Examples are provided concerning the most ingenious solution for the preparation of chromogenic materials, starting from different types of commodity plastics or synthetic polymers and combined with the latest AIE technology to provide the most sensitive response to mechanical stress.

Interfacial bioconjugation on emulsion droplet for biosensors.

Interfacial bioconjugation methods are developed for intact liquid emulsion droplets. Complex emulsion droplets having internal hydrocarbon and fluorocarbon immiscible structured phases maintain a dynamic interface for controlled interfacial reactivity. The internal morphological change after binding to biomolecules is readily visualized and detected by light transmission, which provides a platform for the formation of inexpensive and portable bio-sensing assays for enzymes, antibodies, nucleic acids and carbohydrates.

A 4,4'-bis(2-benzoxazolyl)stilbene luminescent probe: assessment of aggregate formation through photophysics experiments and quantum-chemical calculations.

A combination of experimental and quantum mechanical investigations is applied to the study of the optical features of 4,4'-bis(2-benzoxazolyl)stilbene (BBS) dissolved in solution or in a poly(l-lactic acid) (PLA) thermoplastic matrix at different concentrations. The experimental analyses allow the characterization of BBS solutions and dispersions in terms of absorption and emission features, along with the collection of some key parameters such as fluorescence quantum yield, anisotropy and lifetime, while the computational approach gives a detailed description of the photophysical behavior of BBS in the different environments. For the 10-5 M BBS solution, the fluorescence spectra show the expected peaks at 425 and 455 nm of the non-interacting BBS molecules with a single fluorescence lifetime of 0.85 ns without revealing any aggregation phenomena, prevented by the short lifetime and fast diffusion rate of the monomer. Moreover, the calculated spectra are in excellent agreement with the experiments, thus showing the reliability of the computational approach. In time-resolved emission experiments (TRES) on more concentrated solutions (10-4 M) and on BBS crystals, the presence of an excimer is revealed by the appearance of a broad peak around 540 nm, followed by the disappearance of the two main peaks at 460 nm on a time scale of about 10 ns. The computational analysis attributes this behavior to the formation of aggregates of different geometries. The BBS dispersions in PLA reveal the presence of different BBS architectures depending on the fluorophore content. Even at low concentrations, BBS is mainly dispersed as a monomer in the matrix, spheroid aggregates of about 800-900 nm in diameter are also present and the relevant fluorescence spectra arise from the combination of monomer and aggregate contributions. At higher concentrations, BBS starts forming crystals of a peculiar helicoidal shape, with a diameter of about 2 µm, variable length up to several hundreds of µm and emission spectra similar to those of isolated BBS crystals.

Body Contouring Surgery and the Maintenance of Weight-Loss Following Roux-En-Y Gastric Bypass: A Retrospective Study.

BACKGROUND: Bariatric surgery leads to significant weight loss with reduced morbidity and mortality. However, excess skin as a consequence of weight loss represents a major problem, impacting upon patient's functionality with potential negative effects on weight loss. OBJECTIVES: We evaluated the effect of body-contouring surgery on weight-loss maintenance following bariatric surgery. METHODS: We undertook a retrospective analysis of patients undergoing Roux-en-Y gastric bypass (RYGB) +/- body-contouring surgery (BC). The control group (n = 61) received RYGB, the test group (n = 30) received RYGB+BC 12 to 18 months after bariatric surgery. Each RYGB+BC patient was matched to two control patients for age, sex, glycaemic status, and weight on day of surgery. Per cent weight loss (%WL) was calculated at 3, 6, 12, 24, 36, 48, and 60 months post-RYGB for both groups. RESULTS: The %WL was similar at 3, 6, and 12 months post-RYGB. At 24 months, %WL was 35.6% in the RYGB+BC group and 30.0% in the RYGB group (P < 0.05). At 36 months, the RYGB+BC group maintained their weight loss (%WL 33.0%), in contrast, the RYGB gained weight (%WL = 27.3%, P < 0.05). This trend continued (RYGB+BC vs RYGB) at 48 months (%WL 30.8% vs 27.0%) and at 60 months (%WL 32.2% vs 22.7%, P < 0.05). CONCLUSIONS: Our results suggest patients who undergo body contouring after bariatric surgery are able to lose significantly more weight and maintain weight loss at five years of follow up compared to those undergoing bariatric surgery alone.

Vapochromic features of new luminogens based on julolidine-containing styrene copolymers.

We report on vapochromic films suitable for detecting volatile organic compounds (VOCs), based on new polystyrene copolymers containing julolidine fluorescent molecular rotors (JCAEM). Poly(styrene-co-hydroxyethylmethacrylate) copolymers functionalized with cyanovinyl-julolidine moieties of different compositions were prepared, (P(STY-co-JCAEM)(m) with m = 0.06-0.61). The sensing performance of the spin-coated copolymer films demonstrated significant vapochromism when exposed to VOCs characterized by high vapour pressure and a favourable interaction with the polymer matrix, such as Et2O and CH2Cl2. It is worth mentioning that the fluorescence decrease rate was 7 times faster than that of previously investigated julolidine-based fluorescent molecular rotors dispersed in PS films. This phenomenon was attributed to the better control of the JCAEM moiety distribution in the polymer matrix conferred by the covalent approach, combined with a minimal film thickness of 4 microns. These factors, in concert, strongly accelerate the deactivation pathways of the JCAEM units in the presence of VOCs which interact well. Overall, the present results support the use of julolidine-enriched styrene copolymers as effective chromogenic materials suitable for the fast detection of VOCs.

Fluorescent Polystyrene Films for the Detection of Volatile Organic Compounds Using the Twisted Intramolecular Charge Transfer Mechanism.

Thin films of styrene copolymers containing fluorescent molecular rotors were demonstrated to be strongly sensitive to volatile organic compounds (VOCs). Styrene copolymers of 2-[4-vinyl(1,1'-biphenyl)-4'-yl]-cyanovinyljulolidine (JCBF) were prepared with different P(STY-co-JCBF)(m) compositions (m% = 0.10-1.00) and molecular weights of about 12,000 g/mol. Methanol solutions of JCBF were not emissive due to the formation of the typical twisted intramolecular charge transfer (TICT) state at low viscosity regime, which formation was effectively hampered by adding progressive amounts of glycerol. The sensing performances of the spin-coated copolymer films (thickness of about 4 µm) demonstrated significant vapochromism when exposed to VOCs characterized by high vapour pressure and favourable interaction with the polymer matrix such as THF, CHCl3 and CH2Cl2. The vapochromic response was also reversible and reproducible after successive exposure cycles, whereas the fluorescence variation scaled linearly with VOC concentration, thus suggesting future applications as VOC optical sensors.

GLP-1: a mediator of the beneficial metabolic effects of bariatric surgery?

There has been increasing interest in the role that gut hormones may play in contributing to the physiological changes produced by certain bariatric procedures, such as Roux-en-Y gastric bypass and sleeve gastrectomy. Here, we review the evidence implicating one such gut hormone, glucagon-like peptide-1, as a mediator of the metabolic benefits of these two procedures.

Tuning of dye optical properties by environmental effects: a QM/MM and experimental study.

The present work is aimed at a deeper investigation of two recently synthesized heteroaromatic fluorophores by means of a computational multilayer approach, integrating quantum mechanics (QM) and molecular mechanics (MM). In particular, dispersion of the title dyes in a polymer matrix is studied in connection with potential applications as photoactive species in luminescent solar concentrators (LSCs). Molecular dynamics simulations, based on accurate QM-derived force fields, reveal increased stiffness of these organic dyes when going from CHCl3 solution to the polymer matrix. QM/MM computations of UV spectra for snapshots extracted from MD simulations show that this different flexibility permits explaining the different spectral shapes obtained experimentally for the two different environments. Moreover, the general spectroscopic trends are reproduced well by static computations employing a polarizable continuum description of environmental effects.

Reported appetite, taste and smell changes following Roux-en-Y gastric bypass and sleeve gastrectomy: Effect of gender, type 2 diabetes and relationship to post-operative weight loss.

Reduced energy intake drives weight loss following Roux-en-Y gastric bypass (RYGB) and sleeve gastrectomy (SG) procedures. Post-operative changes in subjective appetite, taste, and smell and food preferences are reported and suggested to contribute to reduced energy intake. We aimed to investigate the prevalence of these changes following RYGB and SG and to evaluate their relationship with weight loss. 98 patients post-RYGB and 155 post-SG from a single bariatric centre were recruited to a cross-sectional study. Participants completed a questionnaire, previously utilised in post-operative bariatric patients, to assess the prevalence of post-operative food aversions and subjective changes in appetite, taste and smell. Anthropometric data were collected and percentage weight loss (%WL) was calculated. The relationship between food aversions, changes in appetite, taste and smell and %WL was assessed. The influence of time post-surgery, gender and type 2 diabetes (T2D) were evaluated. Following RYGB and SG the majority of patients reported food aversions (RYGB = 62%, SG = 59%), appetite changes (RYGB = 91%, SG = 91%) and taste changes (RYGB = 64%, SG = 59%). Smell changes were more common post-RYGB than post-SG (RYGB = 41%, SG = 28%, p = 0.039). No temporal effect was observed post-RYGB. In contrast, the prevalence of appetite changes decreased significantly with time following SG. Post-operative appetite changes associated with and predicted higher %WL post-SG but not post-RYGB. Taste changes associated with and predicted higher %WL following RYGB but not post-SG. There was no gender effect post-RYGB. Post-SG taste changes were less common in males (female = 65%, males = 40%, p = 0.008). T2D status in females did not influence post-operative subjective changes. However, in males with T2D, taste changes were less common post-SG than post-RYGB together with lower %WL (RYGB = 27.5 ± 2.7, SG = 14.6 ± 2.1, p = 0.003). Further research is warranted to define the biology underlying these differences and to individualise treatments.

Toward the design of alkynylimidazole fluorophores: computational and experimental characterization of spectroscopic features in solution and in poly(methyl methacrylate).

The possibilities offered by organic fluorophores in the preparation of advanced plastic materials have been increased by designing novel alkynylimidazole dyes, featuring different push and pull groups. This new family of fluorescent dyes was synthesized by means of a one-pot sequential bromination-alkynylation of the heteroaromatic core, and their optical properties were investigated in tetrahydrofuran and in poly(methyl methacrylate). An efficient in silico pre-screening scheme was devised as consisting of a step-by-step procedure employing computational methodologies by simulation of electronic spectra within simple vertical energy and more sophisticated vibronic approaches. Such an approach was also extended to efficiently simulate one-photon absorption and emission spectra of the dyes in the polymer environment for their potential application in luminescent solar concentrators. Besides the specific applications of this novel material, the integration of computational and experimental techniques reported here provides an efficient protocol that can be applied to make a selection among similar dye candidates, which constitute the essential responsive part of those fluorescent plastic materials.

Early postoperative weight loss predicts maximal weight loss after sleeve gastrectomy and Roux-en-Y gastric bypass.

BACKGROUND: Previous studies show that 'poor responders' to Roux-en-Y gastric bypass (RYGBP) may be identified on the basis of early postoperative weight loss. Early identification of poor responders could allow earlier provision of postoperative behavioural and/or intensive lifestyle interventions and enhance their maximal weight loss. Our aim was to investigate whether early postoperative weight loss predicts the maximal weight loss response after RYGBP and sleeve gastrectomy (SG). METHODS: We undertook a retrospective cross-sectional study of 1,456 adults who underwent either RYGBP (n = 918) or SG (n = 538) as a primary procedure in one of two European centres. Postoperative weight loss was expressed as weight loss velocity (WLV) and percentage weight loss. Linear regression analyses were performed to determine the association of early postoperative weight loss with maximal %WL, including adjustment for baseline variables. RESULTS: There was marked variability in maximal %WL following both RYGBP (mean 32.9 %, range 4.1-60.9 %) and SG (mean 26.2 %, range 1.1-58.3 %). WLV 3-6 months postoperatively was more strongly associated with maximal %WL (r (2) = 0.32 for RYGBP and r (2) = 0.26 for SG, P < 0.001 for both) than either WLV 0-6 weeks or 6 weeks to 3 months postoperatively (r (2) = 0.14 and 0.10 for RYGBP, respectively; r (2) = 0.18 and 0.21 for SG, respectively; P < 0.001 for all). Multiple linear regression analysis, including baseline variables of age, sex, preoperative BMI, type 2 diabetes, ethnicity, and bariatric centre, revealed that 3-6 month WLV was an independent predictor of maximal %WL in both SG and RYGBP groups (standardised ß-coefficients 0.51 and 0.52, respectively; P < 0.001 for both). CONCLUSIONS: There is a marked variability in weight loss response following RYGBP and SG. Early postoperative weight loss can be used to identify patients whose predicted weight loss trajectories are suboptimal. Early targeting of poor responders with more intensive postoperative lifestyle and behavioural support could potentially enhance their weight loss response.

Dye-containing polymers: methods for preparation of mechanochromic materials.

The detection of mechanical stress in polymeric materials through optical variations has attracted considerable interest over the past ten years. In this tutorial review, the current state of knowledge concerning the preparation of polymers with mechanochromic features is summarized. Two types of procedures are illustrated and thoroughly discussed along with their respective structure-property relationships: the first resides in the physical dispersion of the dye in the form of supramolecular aggregates in a preformed polymer matrix; the second involves the covalent insertion of chromophoric units into the macromolecule backbone or side chains. Herein we review the simplicity of the preparative routes available, and their influence over the properties of the resulting dye-polymer systems, by focussing on the most illustrative examples described in the literature. Special reference is made to stimuli-responsiveness as a mechanical means towards innovative smart and intelligent materials.

Staple Line Reinforcement during Sleeve Gastrectomy with SeamGuard: Single-Center Retrospective Case-Control Study over a 5-Year Period.

Introduction: Various techniques and reinforcements have been proposed over the years in order to prevent leaks and bleeding after sleeve gastrectomy (LSG). The aim of this study was to retrospectively compare the staple line complication (SLC) rate in patients who underwent LSG with the use of bioabsorbable membrane (GORE® SEAMGUARD®, GoR) for staple line versus those who received no reinforcement. Methods: Data on all consecutive patients undergoing LSG between 1 January 2014 and 31 December 2018 were retrospectively reviewed. Patients were divided into two groups: the GoR+ group if the SeamGuard (GoR) was used and the GoR- group if no reinforcement was applied on the staple line. Preoperative demographics and rate of SLC were compared between groups. All cases of SLC coming from other centers were also reviewed. Results: A total number of 626 LSGs were performed at our institution during the study period. GoR was applied in 450 (71.9%) cases (GoR+ group), while NR was used in 176 (28.1%) patients (GoR- group). Two (1.13%) cases of leaking and two (1.13%) cases of bleeding occurred in the GoR- group, while no SLC was recorded in patients who received GoR (p < 0.05). Thirteen cases of SLC coming from other institutions were treated at our hospital; all these cases were performed without any SLR. Conclusion: In our case series, the use of GoR reduced the rate of SLC after LSG. In all cases of SLC coming from other institutions, no reinforcement had been applied on the staple line during LSG.

Computational design, synthesis, and mechanochromic properties of new thiophene-based π-conjugated chromophores.

The possibility of exploiting supramolecular architectures for the preparation of innovative mechanochromic devices has been extended by designing novel thienyl-substituted 1,4-bis(ethynyl)benzene dyes, which are characterized by a conjugated, rigid, rodlike core structure. This new family of chromophores was synthesized according to a simple two-step sequential cross-coupling reaction, and the optical properties were investigated in solution and in a polymeric matrix. To tune the mechanochromic performances in smart polymer materials, a virtual screening was set up that was able to select a derivative with optimal spectral features. The effective combination of experimental and computational investigations allowed us to spot those homologues with already potential anisotropic and aggregachromic features and characterized by the best spectral properties and luminescent response. The best candidate was synthesized and dispersed into a polyethylene matrix, indeed achieving an "in silico designed" mechanochromic material. Besides the specific applications of this novel material, the integration of computational and experimental techniques reported here defines an efficient protocol that can be applied to make a selection among similar dye candidates, which constitute the essential responsive part of such supramolecular devices.