Impact of opioid-free analgesia on pain severity and patient satisfaction after discharge from surgery: multispecialty, prospective cohort study in 25 countries

Background: Balancing opioid stewardship and the need for adequate analgesia following discharge after surgery is challenging. This study aimed to compare the outcomes for patients discharged with opioid versus opioid-free analgesia after common surgical procedures.Methods: This international, multicentre, prospective cohort study collected data from patients undergoing common acute and elective general surgical, urological, gynaecological, and orthopaedic procedures. The primary outcomes were patient-reported time in severe pain measured on a numerical analogue scale from 0 to 100% and patient-reported satisfaction with pain relief during the first week following discharge. Data were collected by in-hospital chart review and patient telephone interview 1 week after discharge.Results: The study recruited 4273 patients from 144 centres in 25 countries; 1311 patients (30.7%) were prescribed opioid analgesia at discharge. Patients reported being in severe pain for 10 (i.q.r. 1-30)% of the first week after discharge and rated satisfaction with analgesia as 90 (i.q.r. 80-100) of 100. After adjustment for confounders, opioid analgesia on discharge was independently associated with increased pain severity (risk ratio 1.52, 95% c.i. 1.31 to 1.76; P < 0.001) and re-presentation to healthcare providers owing to side-effects of medication (OR 2.38, 95% c.i. 1.36 to 4.17; P = 0.004), but not with satisfaction with analgesia (beta coefficient 0.92, 95% c.i. -1.52 to 3.36; P = 0.468) compared with opioid-free analgesia. Although opioid prescribing varied greatly between high-income and low- and middle-income countries, patient-reported outcomes did not.Conclusion: Opioid analgesia prescription on surgical discharge is associated with a higher risk of re-presentation owing to side-effects of medication and increased patient-reported pain, but not with changes in patient-reported satisfaction. Opioid-free discharge analgesia should be adopted routinely

Direct Growth of Flexible and Scalable Photocathodes from α‑Brass Substrates

A facile, low cost method to grow robust and adherent, single phase metal oxides from an earth-abundant binary alloy has been outlined and its effectiveness as a photocathode for solar energy harvesting demonstrated. Cu_0.7Zn_0.3 (α-brass) foils were thermally dezincified (removal of surface Zn) at 450 °C and subsequently oxidized, by varying the temperature from 300 to 600 °C. The brass foil served as the oxide growth substrate as well as a conductive electrical contact for subsequent photoelectrochemical testing. CuO nanowires were seen for the 400 and 500 °C samples. ZnO phase was detected within the concave pores on the sample surface. The highest photocurrent of 1.8 mA/cm² at −0.5 V vs Ag/AgCl occurred for the sample oxidized at 500 °C with an incident-photon-to-current-efficiency (IPCE) of 6.9% at 450 nm. This sample corresponds to the oxide with the lowest surface zinc content (10 at. %, measured by X-ray photoelectron spectroscopy), indicating that the presence of ZnO hinders the performance of the photocathode. The approach demonstrated in this work opens up possibilities for making large area, scalable photoelectrodes directly on conductive alloy substrates, leading to simpler electrode fabrication and opportunities for alloy recycling for sustainable energy harvesting

Amorphous Cu_(2-δ)O as Passivation Layer for Ultra Long Stability of Copper Oxide Nanowires in Photoelectrochemical Environments

Core-shell CuO-Cu_2O nanowires with a surface amorphous Cu2-δO layer leads to high stability photocathodes for use in photoelectrochemical splitting of water. The nanowires are synthesized via carbothermal reduction of CuO nanowires at 300°C during which a 2–3 nm conformal and amorphous Cu_(2-δ)O layer is formed on the nanowire surface. This Cu_(2-δ)O layer enhances photocurrent and improves photocorrosion stability of the nanowires. While catalyst-free, pristine CuO nanowires show a photocurrent density is 0.50 mA/cm^2 and a stability of 53% after 3.4 hours of testing at −0.50 V under AM1.5 G conditions; the catalyst-free, carbothermally reduced nanowires achieve a photocurrent density of 0.75 mA/cm^2 and an improved stability of 96% under identical test conditions. The mechanism of enhanced photocurrent and its stability is discussed in the context of extensive pre and post test nanowire characterization

Amorphous Cu_(2-δ)O as Passivation Layer for Ultra Long Stability of Copper Oxide Nanowires in Photoelectrochemical Environments

Core-shell CuO-Cu_2O nanowires with a surface amorphous Cu2-δO layer leads to high stability photocathodes for use in photoelectrochemical splitting of water. The nanowires are synthesized via carbothermal reduction of CuO nanowires at 300°C during which a 2–3 nm conformal and amorphous Cu_(2-δ)O layer is formed on the nanowire surface. This Cu_(2-δ)O layer enhances photocurrent and improves photocorrosion stability of the nanowires. While catalyst-free, pristine CuO nanowires show a photocurrent density is 0.50 mA/cm^2 and a stability of 53% after 3.4 hours of testing at −0.50 V under AM1.5 G conditions; the catalyst-free, carbothermally reduced nanowires achieve a photocurrent density of 0.75 mA/cm^2 and an improved stability of 96% under identical test conditions. The mechanism of enhanced photocurrent and its stability is discussed in the context of extensive pre and post test nanowire characterization

Indirect Phase Transformation of CuO to Cu₂O on a Nanowire Surface

The reduction of CuO nanowires (NWs) to Cu₂O NWs undergoes an indirect phase transformation on the surface: from single crystalline CuO, to a disordered Cu_2−δO phase, and then to crystalline Cu₂O. A 9–12 nm disordered Cu_2−δO is formed on the NW surface by exposing CuO NWs to CO at 1 Torr, 300 °C for 30 min. After 60 min, this layer decreases to 2–3 nm and is eliminated after 180 min. Energy dispersive X-ray spectroscopy using a scanning tunneling electron microscope and across a single NW reveals the disordered layer to be O-rich with respect to Cu₂O with a maximum at. % Cu:O = 1.8. X-ray photoelectron spectroscopy shows adsorbed CO on the surface as evidence of the reduction reaction. Micro-Raman spectroscopy tracks the transformation in NWs as a function of reduction time. A CO enabled surface reduction reaction coupled to diffusion-limited transport of “nonlattice” O to the surface is proposed as a mechanism for Cu_2−δO formation. The initial buildup of out-diffusing O to the surface appears to aid the formation of the disordered surface layer. The transformation follows Ostwald–Lussac’s law which predicts formation of unstable phases over stable phases, when phase transformation rates are limited by kinetic or diffusional processes. The study provides a generalized approach for facile growth of few nanometer transient layers on multivalent, metal oxide NW surfaces

Highly Conducting, <i>n</i>‑Type Bi₁₂O₁₅Cl₆ Nanosheets with Superlattice-like Structure

Modulating the type and magnitude of electrical conductivity remains a basic requirement for a semiconductor’s widespread acceptability and use. Here, we convert nanosheets of BiOCl, a V–VI–VII ternary semiconductor, to an oxygen-rich Bi₁₂O₁₅Cl₆ phase. In the process, the intrinsic conductivity switches from <i>p</i>-type to <i>n</i>-type. The phase change is achieved using a vacuum annealing step at 500 °C for 1 h. BiOCl nanosheets convert to the Bi₁₂O₁₅Cl₆ phase via volatilization of BiCl₃ resulting in a unique superlattice like structure with a periodicity of 1.48 nm. Correspondingly, the band gap decreases from 3.41 to 2.48 eV from the raising of the valence band edge. Activation energy for electrical conductivity reduces from 862 meV for BiOCl to 778 meV for Bi₁₂O₁₅Cl₆, and a corresponding photoconductivity increase of 80× is observed. Density functional theory calculations predict changes to the valence band and increase in the Fermi level toward the conduction band edge for the Bi₁₂O₁₅Cl₆ nanosheetsin accordance with experimental data. The availability of both <i>p</i>- and <i>n</i>-type ternary semiconducting systems widen the application base for Bi–O–Cl based materials

Cationically Substituted Bi_0.7Fe_0.3OCl Nanosheets as Li Ion Battery Anodes

Cation substitution of Bi³⁺ with Fe³⁺ in BiOCl leads to the formation of ionically layered Bi_0.7Fe_0.3OCl nanosheets. The synthesis follows a hydrolysis route using bismuth­(III) nitrate and iron­(III) chloride, followed by postannealing at 500 °C. Room temperature electrical conductivity improves from 6.11 × 10^–8 S/m for BiOCl to 6.80 × 10^–7 S/m for Bi_0.7Fe_0.3OCl. Correspondingly, the activation energy for electrical conduction reduces from 862 meV for pure BiOCl to 310 meV for Bi_0.7Fe_0.3OCl. These data suggest improved charge mobility in Bi_0.7Fe_0.3OCl nanosheets. Density functional theory calculations confirm this behavior by predicting a high density of states near the Fermi level for Bi_0.7Fe_0.3OCl. The improvement in electrical conductivity is exploited in the electrochemical performance of Bi_0.7Fe_0.3OCl nanosheets. The insertion capacity of Li⁺ ions shows an increase of 2.5×, from 215 mAh·.g^–1 for undoped BiOCl to 542 mAh·g^–1 for Bi_0.7Fe_0.3OCl after 50 cycles at a current density of 50 mA·g^–1. Thus, the direct substitution of Bi³⁺ sites with Fe³⁺ in BiOCl results in nanosheets of an ionically layered ternary semiconductor compound which is attractive for Li ion battery anode applications