Axillary Brachial Plexus Block Compared with Other Regional Anesthesia Techniques in Distal Upper Limb Surgery: A Systematic Review and Meta-Analysis.

Background: Several regional anesthesia (RA) techniques have been described for distal upper limb surgery. However, the best approach in terms of RA block success rate and safety is not well recognized. Objective: To assess and compare the surgical anesthesia and efficacy of axillary brachial plexus block with other RA techniques for hand and wrist surgery. The attainment of adequate surgical anesthesia 30 min after block placement was considered a primary outcome measure. Additionally, successful block outcomes were required without the use of supplemental local anesthetic injection, systemic opioid analgesia, or the need to convert to general anesthesia. Methods: We performed a systematic search in the following databases: MEDLINE, EMBASE, Cochrane Database of Systematic Reviews, and CENTRAL. RCTs comparing axillary blocks with other brachial plexus block techniques, distal peripheral forearm nerve block, intravenous RA, and the wide-awake local anesthesia no tourniquet (WALANT) technique were included. Results: In total, 3070 records were reviewed, of which 28 met the inclusion criteria. The meta-analysis of adequate surgical anesthesia showed no significant difference between ultrasound-guided axillary block and supraclavicular block (RR: 0.94 [0.89, 1.00]; p = 0.06; I2 = 60.00%), but a statistically significant difference between ultrasound-guided axillary block and infraclavicular block (RR: 0.92 [0.88, 0.97]; p < 0.01; I2 = 53.00%). Ultrasound-guided infraclavicular blocks were performed faster than ultrasound-guided axillary blocks (SMD: 0.74 [0.30, 1.17]; p < 0.001; I2 = 85.00%). No differences in performance time between ultrasound-guided axillary and supraclavicular blocks were demonstrated. Additionally, adequate surgical anesthesia onset time was not significantly different between ultrasound-guided block approaches: ultrasound-guided axillary blocks versus ultrasound-guided supraclavicular blocks (SMD: 0.52 [-0.14, 1.17]; p = 0.12; I2 = 86.00%); ultrasound-guided axillary blocks versus ultrasound-guided infraclavicular blocks (SMD: 0.21 [-0.49, 0.91]; p = 0.55; I2 = 92.00%). Conclusions: The RA choice should be individualized depending on the patient, procedure, and operator-specific parameters. Compared to ultrasound-guided supraclavicular and infraclavicular block, ultrasound-guided axillary block may be preferred for patients with significant concerns of block-related side effects/complications. High heterogeneity between studies shows the need for more robust RCTs.

SEM Image Processing Assisted by Deep Learning to Quantify Mesoporous γ-Alumina Spatial Heterogeneity and Its Predicted Impact on Mass Transfer.

The pore network architecture of porous heterogeneous catalyst supports has a significant effect on the kinetics of mass transfer occurring within them. Therefore, characterizing and understanding structure-transport relationships is essential to guide new designs of heterogeneous catalysts with higher activity and selectivity and superior resistance to deactivation. This study combines classical characterization via N2 adsorption and desorption and mercury porosimetry with advanced scanning electron microscopy (SEM) imaging and processing approaches to quantify the spatial heterogeneity of γ-alumina (γ-Al2O3), a catalyst support of great industrial relevance. Based on this, a model is proposed for the spatial organization of γ-Al2O3, containing alumina inclusions of different porosities with respect to the alumina matrix. Using original, advanced SEM image analysis techniques, including deep learning semantic segmentation and porosity measurement under gray-level calibration, the inclusion volume fraction and interphase porosity difference were identified and quantified as the key parameters that served as input for effective tortuosity factor predictions using effective medium theory (EMT)-based models. For the studied aluminas, spatial porosity heterogeneity impact on the effective tortuosity factor was found to be negligible, yet it was proven to become significant for an inclusion content of at least 30% and an interphase porosity difference of over 20%. The proposed methodology based on machine-learning-supported image analysis, in conjunction with other analytical techniques, is a general platform that should have a broader impact on porous materials characterization.

Machine Learning Assisted Experimental Characterization of Bubble Dynamics in Gas-Solid Fluidized Beds.

This study introduces a machine learning (ML)-assisted image segmentation method for automatic bubble identification in gas-solid quasi-2D fluidized beds, offering enhanced accuracy in bubble recognition. Binary images are segmented by the ML method, and an in-house Lagrangian tracking technique is developed to track bubble evolution. The ML-assisted segmentation method requires few training data, achieves an accuracy of 98.75%, and allows for filtering out common sources of uncertainty in hydrodynamics, such as varying illumination conditions and out-of-focus regions, thus providing an efficient tool to study bubbling in a standard, consistent, and repeatable manner. In this work, the ML-assisted methodology is tested in a particularly challenging case: structured oscillating fluidized beds, where the spatial and time evolution of the bubble position, velocity, and shape are characteristics of the nucleation-propagation-rupture cycle. The new method is validated across various operational conditions and particle sizes, demonstrating versatility and effectiveness. It shows the ability to capture challenging bubbling dynamics and subtle changes in velocity and size distributions observed in beds of varying particle size. New characteristic features of oscillating beds are identified, including the effect of frequency and particle size on the bubble morphology, aspect, and shape factors and their relationship with the stability of the flow, quantified through the rate of coalescence and splitting events. This type of combination of classic analysis with the application of the ML assisted techniques provides a powerful tool to improve standardization and address the reproducibility of hydrodynamic studies, with the potential to be extended from gas-solid fluidization to other multiphase flow systems.

From Biomimicking to Bioinspired Design of Electrocatalysts for CO2 Reduction to C1 Products.

The electrochemical reduction of CO2 (CO2 RR) is a promising approach to maintain a carbon cycle balance and produce value-added chemicals. However, CO2 RR technology is far from mature, since the conventional CO2 RR electrocatalysts suffer from low activity (leading to currents <10 mA cm-2 in an H-cell), stability (<120 h), and selectivity. Hence, they cannot meet the requirements for commercial applications (>200 mA cm-2 , >8000 h, >90 % selectivity). Significant improvements are possible by taking inspiration from nature, considering biological organisms that efficiently catalyze the CO2 to various products. In this minireview, we present recent examples of enzyme-inspired and enzyme-mimicking CO2 RR electrocatalysts enabling the production of C1 products with high faradaic efficiency (FE). At present, these designs do not typically follow a methodical approach, but rather focus on isolated features of biological systems. To achieve disruptive change, we advocate a systematic design methodology that leverages fundamental mechanisms associated with desired properties in nature and adapts them to the context of engineering applications.

Bioinspired 3D microprinted cell scaffolds: Integration of graph theory to recapitulate complex network wiring in lymph nodes.

Physical networks are ubiquitous in nature, but many of them possess a complex organizational structure that is difficult to recapitulate in artificial systems. This is especially the case in biomedical and tissue engineering, where the microstructural details of 3D cell scaffolds are important. Studies of biological networks-such as fibroblastic reticular cell (FRC) networks-have revealed the crucial role of network topology in a range of biological functions. However, cell scaffolds are rarely analyzed, or designed, using graph theory. To understand how networks affect adhered cells, 3D culture platforms capturing the complex topological properties of biologically relevant networks would be needed. In this work, we took inspiration from the small-world organization (high clustering and low path length) of FRC networks to design cell scaffolds. An algorithmic toolset was created to generate the networks and process them to improve their 3D printability. We employed tools from graph theory to show that the networks were small-world (omega factor, ω = -0.10 ± 0.02; small-world propensity, SWP = 0.74 ± 0.01). 3D microprinting was employed to physicalize networks as scaffolds, which supported the survival of FRCs. This work, therefore, represents a bioinspired, graph theory-driven approach to control the networks of microscale cell niches.

Adjuvants for balanced anesthesia in ambulatory surgery.

Balanced anesthesia relies on the simultaneous administration of different drugs to attain an anesthetic state. The classic triad of anesthesia is a combination of a hypnotic, an analgesic, and a neuromuscular blocker. It is predominantly the analgesic pillar of this triad that became more and more supported by adjuvant therapy. The aim of this approach is to evolve into an opioid-sparing technique to cope with undesirable side effects of the opioids and is fueled by the opioid epidemic. The optimal strategy for balanced general anesthesia in ambulatory surgery must aim for a transition to a multimodal analgesic regimen dealing with acute postoperative pain and ideally reduce the most common adverse effects patients are faced with at home; sore throat, delayed awakening, memory disturbances, headache, nausea and vomiting, and negative behavioral changes. Over the years, this continuum of "multimodal general anesthesia" adopted many drugs with different modes of action. This review focuses on the most recent evidence on the different adjuvants that entered clinical practice and gives an overview of the different mechanisms of action, the potential as opioid-sparing or hypnotic-sparing drugs, and the applicability specifically in ambulatory surgery.

Surface barriers to mass transfer in nanoporous materials for catalysis and separations.

Surface barriers to mass transfer in various nanoporous materials have been increasingly identified. These past few years especially, a significant impact on catalysis and separations has come to light. Broadly speaking, there are two types of barriers: internal barriers, which affect intraparticle diffusion, and external barriers, which determine the uptake and release rates of molecules into and out of the material. Here, we review the literature on surface barriers to mass transfer in nanoporous materials and describe how the existence and influence of surface barriers has been characterized, aided by molecular simulations and experimental measurements. As this is a complex, evolving research topic, without consensus from the scientific community at the time of writing, we present various current viewpoints, not always in agreement, on the origin, nature, and function of such barriers in catalysis and separation. We also emphasize the need for considering all the elementary steps of the mass transfer process in optimally designing new nanoporous and hierarchically structured adsorbents and catalysts.

Prospective audit on fasting status of elective ambulatory surgery patients, correlated to gastric ultrasound.

INTRODUCTION: Recent guidelines advocate a preoperative fasting interval of 6 h for solid food, 4 h for breast milk and 2 h for clear fluids. Long nil per mouth intervals give rise to complications and discomfort in the perioperative period. Gastric ultrasound is easily accessible and generates reliable information about gastric content. PATIENTS AND METHODS: One hundred patients were offered a questionnaire regarding preoperative fasting. Important outcome measures were hour of last meal, last clear fluids intake, the source of preoperative information. Gastric ultrasound was performed in prone position and lateral decubitus. RESULTS: The mean duration of fasting for solid food was 13h29 and 9h51 for clear fluids. 48% of patients were well aware of the correct fasting guidelines. The most frequent source of information was the preoperative phone call. Gastric ultrasound only found insignificant amounts of gastric content. DISCUSSION: Too few patients are aware of the correct guidelines or fear complications and therefore adhere to the nil per mouth from midnight as most conservative measure. A phone call informing patients about the hour of surgery and allowing clear fluid intake until 2 h before surgery, is still not convincing enough. Some health care providers advise their patients the nil per mouth from midnight rule, due to risk of interfering with the operating room schedule. CONCLUSION: It is still difficult to implement liberal intake of clear fluids according to current guidelines. Ambulatory surgery patients have long fasting intervals with decrease of subjective well-being and increased incidence of hunger and thirst.

Enhanced Structural Control of Soft-Templated Mesoporous Inorganic Thin Films by Inert Processing Conditions.

Mesoporous thin films are widely used for applications in need of high surface area and efficient mass and charge transport properties. A well-established fabrication process involves the supramolecular assembly of organic molecules (e.g., block copolymers and surfactants) with inorganic materials obtained by sol-gel chemistry. Typically, subsequent calcination in air removes the organic template and reveals the porous inorganic network. A significant challenge for such coatings is the anisotropic shrinkage due to the volume contraction related to solvent evaporation, inorganic condensation, and template removal, affecting the final porosity as well as pore shape, size, arrangement, and accessibility. Here, we show that a two-step calcination process, composed of high-temperature treatment in argon followed by air calcination, is an effective fabrication strategy to reduce film contraction and enhance structural control of mesoporous thin films. Crucially, the formation of a transient carbonaceous scaffold enables the inorganic matrix to fully condense before template removal. The resulting mesoporous films retain a higher porosity as well as bigger pores with extended porous order. Such films present favorable characteristics for mass transport of large molecules. This is demonstrated for lysozyme adsorption into the mesoporous thin films as an example of enzyme storage.

Five vs. two initial rescue breaths during infant basic life support: A manikin study using bag-mask-ventilation.

Background and objectives: Children are more likely to suffer a hypoxic-ischaemic cause for cardiac arrest. Early ventilation may provide an advantage in outcome during paediatric cardiopulmonary resuscitation [CPR]. European Resuscitation Council guidelines recommend five initial rescue breaths [IRB] in infants, stemming from the hypothesis that rescuers might need 5 attempts in order to deliver 2 effective ventilations. This study aimed to verify this hypothesis. Methods: Participants (n = 112, convenience sample) were medical students from the Faculty of Medicine and Health Sciences Ghent University, Belgium. Students were divided into duos and received a 15 min just-in-time training regarding the full CPR-cycle using BMV. Participants then performed five cycles of 2-person CPR. The IRB were given by 1-person BMV, as opposed to a 2-persons technique during the further CPR-cycle. Correct ventilations for the infant were defined as tidal volumes measured (Laerdal® Q-CPR) between 20 and 60 ml, with n = 94 participants included in the analysis. The primary outcome consisted of the difference in the % of medical student duos providing at least 2 effective IRB between 2 and 5 attempts. Results: Off all duos, 55,3% provided correct volumes during their first 2 initial ventilations. An increase up to 72,4% was noticed when allowing 5 ventilations. The proportional difference between 2 and 5 IRB allowed was thus significant [17,0%, 95% confidence interval (5.4; 28.0)]. Conclusion: In this manikin study, 5 IRB attempts during infant CPR with BMV increased the success rate in delivering 2 effective ventilations. Besides, students received training emphasizing the need for 5 initial rescue breaths. This study provides evidence supporting European Resuscitation Council guidelines.

Encouraging Digital Patient Portal Use in Ambulatory Surgery: A Mixed Method Research of Patients and Health Care Professionals Experiences and Perceptions.

PURPOSE: As more complex surgery is performed in 1-day admissions there is a growing demand for appropriate postoperative follow-up. A digital patient portal (DPP) is a promising tool to support this and increase patients' quality of recovery. However, both patients and health care professionals have not fully embraced this eHealth technology. This study investigates the extent to which a patient portal is used in a tertiary ambulatory surgical care unit and assesses usability, applicability and user-friendliness both for the patient and health care worker. DESIGN: Mixed method research design combining qualitative and quantitative methods. METHODS: Four hundred and fifteen patients undergoing knee arthroscopic surgery or endonasal sinus surgery were included. Quantitative log data from the patient platform, clinical outcome measures and a patient questionnaire were used. Additionally, qualitative data was collected through interviews (with patients, n = 13; involved caregivers and physicians, n = 7) and observations (first introduction to patient with platform and team meetings, n = 15). FINDINGS: Forty percent of the included patients effectively used the patient platform (≥1 login). The patients mainly used the platform for gathering information; 62% of the active patients on the platform registered questionnaires initiated from the surgery center (eg, preoperative questionnaire) or diaries (e.g, daily follow-up using the Quality of Recovery Scale). Different barriers and facilitators toward DPP implementation were noted. Attention should be paid to the intrinsic and extrinsic motivation for using the portal and to the added value of the portal for the patient and health care professionals. CONCLUSIONS: Patients' perceptions of the DPP were positive and an increase in DPP use was observed during the study due to adjustments (eg, technical adjustments). However, a decline over time was noticed. The role of intrinsic and extrinsic motivation of all included parties needs to be further corroborated.

Unanticipated admission after ambulatory surgery in the pediatric population: a single-center retrospective analysis.

INTRODUCTION: The incidence of adverse events in day surgery is an important quality indicator. This retrospective study investigated factors independently associated with unanticipated admission of pediatric patients after ambulatory surgery. PATIENTS AND METHODS: Ambulatory pediatric patients requiring unanticipated admission between January 2016 and December 2018 were compared to ambulatory pediatric patients who were discharged home after a planned surgery. Demographic data, organizational data, American Society of Anesthesiologists (ASA) classification, type of surgery, type of anesthesia, length of surgery, time of completion of the surgery, campus site, and season were collected in both groups. The reason for unexpected admission was classified according to four subtypes: anesthetic, medical, social/organizational and surgical reason, respectively. Multivariate logistic regression was used to identify independent factors associated with unanticipated admission. RESULTS: From a total of 4235 pediatric patients, 78 children (1.9%) required unanticipated admission. The reasons for admission were anesthetic n = 29 (37.3%), surgical n = 20 (25.6%), medical n = 16 (20.5%) and social/organizational n = 13 (16.6%). Age <2 years (odds ratio [OR] 3.005, 95% confidence interval (CI) 1.500-6.018; ASA class 2 (OR 2.144; 95% CI 1.193-3.852); ASA class 3 (OR 11.617; CI 5.698-23.685); length of surgery >2 h (OR 3.056; CI 1.829-5.107); completion of surgery > 2:30 PM (OR 3.507; CI 1.854-6.633) and campus site (OR 3.628; CI 1.991-6.610) were factors significantly associated with unanticipated admission. CONCLUSION: Children are less likely to be admitted after ambulatory surgery when preoperatively carefully selected and when prioritized considering age, general health condition and invasiveness of the surgery.

Gold nanoparticles with tailored size through ligand modification for catalytic applications.

The active sites of catalysts can be tuned by using appropriate organic moieties. Here, we describe a facile approach to synthesise gold nanoparticles (AuNPs) using various Au(I) precursors. The core size of these AuNPs can be precisely tailored by varying the steric hindrance imposed by bound ligands. An interesting relationship is deduced that correlates the steric hindrance around the metal to the final size of the nanoparticles. The synthesised AuNPs are immobilised onto TS-1 zeolite (Au/TS-1) with minimal change in the final size of the AuNPs. The catalytic performance of Au/TS-1 catalyst is evaluated for the direct gas phase epoxidation of propylene with hydrogen and oxygen, an environmentally friendly route to produce propylene oxide. The results indicate that smaller AuNPs exhibit enhanced catalytic activity and selectivity. Furthermore, this synthetic approach is beneficial when tailored synthesis of gold nanoparticles of specific sizes is required.

Mixed-dimensional membranes: chemistry and structure-property relationships.

Tremendous progress in two-dimensional (2D) nanomaterial chemistry affords abundant opportunities for the sustainable development of membranes and membrane processes. In this review, we propose the concept of mixed dimensional membranes (MDMs), which are fabricated through the integration of 2D materials with nanomaterials of different dimensionality and chemistry. Complementing mixed matrix membranes or hybrid membranes, MDMs stimulate different conceptual thinking about designing advanced membranes from the angle of the dimensions of the building blocks as well as the final structures, including the nanochannels and the bulk structures. In this review, we survey MDMs (denoted nD/2D, where n is 0, 1 or 3) in terms of the dimensions of membrane-forming nanomaterials, as well as their fabrication methods. Subsequently, we highlight three kinds of nanochannels, which are 1D nanochannels within 1D/2D membranes, 2D nanochannels within 0D/2D membranes, and 3D nanochannels within 3D/2D membranes. Strategies to tune the physical and chemical microenvironments of the nanochannels as well as the bulk structures based on the size, type, structure and chemical character of nanomaterials are discussed. Some representative applications of MDMs are illustrated for gas molecular separations, liquid molecular separations, ionic separations and oil/water separation. Finally, current challenges and a future perspective on MDMs are presented.

Syncope in Dental Practices: A Systematic Review on Aetiology and Management.

INTRODUCTION: This systematic review aimed to give an overview of the current evidence surrounding the aetiology and management in terms of treatment and prevention of syncope in dental practices. Alongside the occurrence, the practitioner's competence, and the association between syncope and local anaesthetics were discussed. METHODS: An electronic search in EMBASE, Web of Science, PubMed, Cochrane databases and a hand search were performed by 2 independent reviewers to identify studies up to November 2019. Eligibility criteria were applied and relevant data was extracted. Inclusion criteria covered all types of dental treatment under local anaesthesia or conscious sedation performed by a wide range of oral health care workers in their practices. Risk of bias of the included studies was assessed using the methodological tools recommend by Zeng et al.1 No restrictions were made to exclude papers from qualitive analysis based on risk of bias assessment. RESULTS: The search yielded a total of 18 studies for qualitative analysis. With the exception of one prospective cohort study, all articles were considered having a high risk of bias. Meta-analysis showed that dentists encountered on average 1.2 cases of syncope per year. The male gender (RR = 2.69 [1.03, 7.02]), dental fear (RR = 3.55 [2.22, 5.70]), refusal of local anaesthesia in non-acute situations (OR = 12.9) and the use of premedication (RR = 4.70, [1.30, 16.90]) increased the risk for syncope. Treatment and prevention were underreported as both were solely discussed in one study. The supine recovery position with raised legs and oxygen administration (15l/min) was presented as an effective treatment. The Medical Risk-Related History (MRRH) system was proposed as prevention protocol, yet this protocol was ineffective in reducing incidence rates (p = 0.27). The majority of dentists (79.2%) were able to diagnose syncope, yet most (86%) lacked the skills for appropriate treatment. Only 57,6% of dental practices were equipped with an oxygen cylinder. CONCLUSIONS: Syncope is the most common emergency in dental practices. Nonetheless, the vast majority of dentists do not seem competent nor prepared to manage this emergency. Psychogenic factors seem to play an important role in provoking syncope. Placing the patient in a supine reclined position with raised legs in combination with the administration of oxygen seems effective for regaining consciousness. Although valuable in many aspects, risk assessment by medical history taking is not proven to result in fewer episodes. The strength of these conclusions is low based on GRADE guidelines.2.

Laryngeal mask airway protector generates higher oropharyngeal leak pressures compared to the laryngeal mask airway supreme: A randomized clinical trial in the ambulatory surgery unit.

BACKGROUND AND AIMS: The Laryngeal Mask Airway (LMA) Protector™ is one of the latest introduced supraglottic airway devices. It provides access and functional separation of the respiratory and digestive tracts. Compared to the LMA Supreme™, it has two digestive ports, one to provide suction in the pharyngeal region and one for gastric tube insertion. High oropharyngeal leak pressure is a marker for safe ventilation when using LMA devices. We hypothesized that oropharyngeal leak pressure of the LMA Protector™ is 5 cm H2O higher than the oropharyngeal leak pressure of the LMA Supreme™ at various cuff volumes. Secondary outcome measures were ease of insertion of both masks, fiberoptic confirmation of correct positioning, failures of insertion, presence of blood staining, sore throat, presence of air leak and insertion time. MATERIAL AND METHODS: American Society of Anesthesiologists (ASA) I-III patients aged >18 years, scheduled for elective minor ambulatory surgery under general anesthesia with a LMA were included. Patients were randomized in the LMA Protector™ or LMA Supreme™ group based on a computer-generated random sequence table. After general anesthesia induction, oropharyngeal leak pressures were measured. RESULTS: Oropharyngeal leak pressures were significantly higher (P < 0.0001) for LMA Protector™ compared to LMA Supreme™ at different cuff volumes and a cuff pressure of 65 cm H2O. Insertion time was significantly higher for the LMA Protector™ (29 sec) [interquartile range (IQR) 23, 35] compared to the LMA Supreme™ (19 sec) (IQR 16, 22) (P < 0.0001). There were no statistically significant differences in ease of insertion (number of attempts for succesful positioning), failures of insertion, presence of blood staining, sore throat or presence of air leak. CONCLUSION: Oropharyngeal leak pressures were consistently higher (>5 cm H2O) for LMA Protector™ compared to LMA Supreme™. LMA Protector™, therefore, allows effective ventilation at higher airway pressures than LMA Supreme™. TRIAL REGISTRATION: http://clinicaltrials.gov.NCT03462550.

Postoperative innovative technology for ambulatory anesthesia and surgery.

PURPOSE OF REVIEW: To give an overview of the impact of different forms of telehealth that are currently used in ambulatory anesthesia and surgery. Telehealth is applicable during the early recovery and intermediate recovery period (e.g. monitoring of quality of recovery), and as a tool for postoperative check-up during the late recovery phase. RECENT FINDINGS: Postoperative follow-up after ambulatory surgery is still crucial to maintain quality of care as pain and postoperative nausea and vomiting remain common adverse events. There is a surge of telehealth applications from procedure-specific commercial smartphone apps (mHealth) to complete digital patient platforms instituted by the government. However, patient and healthcare provider engagement is not universal. Usability of these applications is mandatory as well as identifying and overcoming the barriers to its use. SUMMARY: Telehealth gives many opportunities for postoperative follow-up of ambulatory surgery patients. Clear evidence on the benefits of telehealth in ambulatory surgery is however still sparse. Future research should focus on telehealth for improving quality and safety of postoperative recovery, convincing policymakers for reimbursement encouraging healthcare providers and patients to engage in telehealth.

Precisely Engineered Supported Gold Clusters as a Stable Catalyst for Propylene Epoxidation.

Designing a stable and selective catalyst with high H2 utilisation is of pivotal importance for the direct gas-phase epoxidation of propylene. This work describes a facile one-pot methodology to synthesise ligand-stabilised sub-nanometre gold clusters immobilised onto a zeolitic support (TS-1) to engineer a stable Au/TS-1 catalyst. A non-thermal O2 plasma technique is used for the quick removal of ligands with limited increase in particle size. Compared to untreated Au/TS-1 catalysts prepared using the deposition precipitation method, the synthesised catalyst exhibits improved catalytic performance, including 10 times longer lifetime (>20 days), increased PO selectivity and hydrogen efficiency in direct gas phase epoxidation. The structure-stability relationship of the catalyst is illustrated using multiple characterisation techniques, such as XPS, 31 P MAS NMR, DR-UV/VIS, HRTEM and TGA. It is hypothesised that the ligands play a guardian role in stabilising the Au particle size, which is vital in this reaction. This strategy is a promising approach towards designing a more stable heterogeneous catalyst.

Effect of External Surface Diffusion Barriers on Platinum/Beta-Catalyzed Isomerization of n-Pentane.

We have developed a generalizable strategy to quantify the effect of surface barriers on zeolite catalysis. Isomerization of n-pentane, catalyzed by Pt/Beta, is taken as a model reaction system. Firstly, the surface modification by chemical liquid deposition of SiO2 was carried out to control the surface barriers on zeolite Beta crystals. The deposition of SiO2 leads to a very slight change in the physical properties of Beta crystals, but an obvious reduction in Brønsted acid sites. Diffusion measurements by the zero-length column (ZLC) method show that the apparent diffusivity of n-pentane can be more than doubled after SiO2 deposition, indicating that the surface barriers have been weakened. Catalytic performance was tested in a fixed-bed reactor, showing that the apparent catalytic activity improved by 51-131 % after SiO2 deposition. These results provide direct proof that reducing surface barriers can be an effective route to improve zeolite catalyst performance deteriorated by transport limitations.

Nature-Inspired Chemical Engineering for Process Intensification.

A nature-inspired solution (NIS) methodology is proposed as a systematic platform for innovation and to inform transformative technology required to address Grand Challenges, including sustainable development. Scalability, efficiency, and resilience are essential to nature, as they are to engineering processes. They are achieved through underpinning fundamental mechanisms, which are grouped as recurring themes in the NIS approach: hierarchical transport networks, force balancing, dynamic self-organization, and ecosystem properties. To leverage these universal mechanisms, and incorporate them effectively into engineering design, adaptations may be needed to accommodate the different contexts of nature and engineering applications. Nature-inspired chemical engineering takes advantage of the NIS methodology for process intensification, as demonstrated here in fluidization, catalysis, fuel cell engineering, and membrane separations, where much higher performance is achieved by rigorously employing concepts optimized in nature. The same approach lends itself to other applications, from biomedical engineering to information technology and architecture.