Tunable Porous Coordination Polymers for the Capture, Recovery and Storage of Inhalation Anesthetics

Synthesis, structure and properties of coordination polymers formed from bridging 4-hydroxybenzoic acid anions

The combination of 4-hydroxbenzoic acid with metal ions Li+, Mg2+ and Cu2+ leads to the formation of novel 2D and 3D networks.

Degradable and processable polymer monoliths with open-pore porosity for selective CO2 and iodine adsorption

A task-specific design of biodegradable and processable porous polymers is one of the primary requisite for their efficient day-to-day use to minimize polymer waste. Herein, a surfactant (or additive)-free method is reported for the synthesis of a processable and degradable aliphatic open-pore porous polyelectrolyte monolith for the removal of gaseous pollutants such as iodine and CO2. This is achieved via a colloidal templating method. In the 1st stage, cationic colloidal nanoparticles containing reactive amines and acrylamide groups were formed via the phase separation of hyperbranched polyaminoamides in water (sol). These cationic nanoparticles (which acted as both templates and macromers) further reacted to form a gel, which upon freeze-drying leads to the formation of a polymer monolith with an open-pore porous morphology and hierarchical porosity throughout its structure. During gelation, the shape of the monolith can be controlled using suitable templates and a similar strategy was used to prepare porous thin films. The monolith has shown excellent iodine adsorption ability (5000 mg g-1 in the vapor phase and 2663 mg g-1 in the solution phase) with good reusability and CO2 adsorption ability (60 mg g-1), with CO2/CH4 and CO2/N2 selectivities of 18.5 and 6.7, respectively. The degradability of the materials was studied in detail at different pH, confirming their easy degradability in aqueous solutions and a higher degradability at basic pH.

Recovery of Sevoflurane Anesthetic Gas Using an Organosilica Membrane in Conjunction with a Scavenging System

Approximately 95% of the anesthetic gas administered to a patient is exhaled and ultimately released into the atmosphere. Most anesthetic gases have high global warming potential and so this approach adds significantly to the global greenhouse gas footprint. In this work, we develop a feasible means to capture such an anesthetic gas (sevoflurane) before it is released to the hospital scavenging system so that it is retained within the anesthetic circuit. Sevoflurane is retained using a microporous 1,2-bis(triethoxysilyl)ethane (BTESE) membrane prepared by a sol-gel method. The use of a ceramic membrane facilitates sanitization at high temperatures. A rapid thermal processing (RTP) technique is employed to reduce production time and to create a looser organosilica network, resulting in higher gas permeances, compared with the membrane synthesized from conventional thermal processing. The RTP membrane shows a slight decline in gas permeance when used with a dry mixture of CO₂/N₂/sevoflurane. This permeance falls again under 20% relative humidity feed conditions but the CO₂/sevoflurane selectivity increases. The membrane performance shows little variation when the relative humidity is further increased. These promising results demonstrate that this microporous BTESE membrane has great potential for the recovery of sevoflurane in an anesthetic application.

The elusive crystals of calcium acetate hemihydrate: chiral rods linked by parallel hydrophilic strips

The chance discovery of crystals of calcium acetate hemihydrate, which is commonly formed on calcareous heritage objects, has allowed its single crystal structure determination; this remarkable crystal structure consists of chiral rod-like units.

Environmental sustainability in anaesthesia and critical care

The detrimental health effects of climate change continue to increase. Although health systems respond to this disease burden, healthcare itself pollutes the atmosphere, land, and waterways. We surveyed the 'state of the art' environmental sustainability research in anaesthesia and critical care, addressing why it matters, what is known, and ideas for future work. Focus is placed upon the atmospheric chemistry of the anaesthetic gases, recent work clarifying their relative global warming potentials, and progress in waste anaesthetic gas treatment. Life cycle assessment (LCA; i.e. 'cradle to grave' analysis) is introduced as the definitive method used to compare and contrast ecological footprints of products, processes, and systems. The number of LCAs within medicine has gone from rare to an established body of knowledge in the past decade that can inform doctors of the relative ecological merits of different techniques. LCAs with practical outcomes are explored, such as the carbon footprint of reusable vs single-use anaesthetic devices (e.g. drug trays, laryngoscope blades, and handles), and the carbon footprint of treating an ICU patient with septic shock. Avoid, reduce, reuse, recycle, and reprocess are then explored. Moving beyond routine clinical care, the vital influences that the source of energy (renewables vs fossil fuels) and energy efficiency have in healthcare's ecological footprint are highlighted. Discussion of the integral roles of research translation, education, and advocacy in driving the perioperative and critical care environmental sustainability agenda completes this review.

The Effect of Sterically Active Ligand Substituents on Gas Adsorption within a Family of 3D Zn-Based Coordination Polymers

An investigation of the adsorption properties of two structurally related, 3D coordination polymers of composition Zn(2-Mehba) and Zn(2,6-Me₂hba) (2-Mehba = the dianion of 2-methyl-4-hydroxybenzoic acid and 2,6-Me₂hba = the dianion of 2,6-dimethyl-4-hydroxybenzoic acid) is presented. A common feature of these structures are parallel channels that are able to accommodate appropriately sized guest molecules. The structures differ with respect to the steric congestion within the channels arising from methyl groups appended to the bridging ligands of the network. The host network, Zn(2-Mehba), is able to take up appreciable quantities of H₂ (77 K) and CO₂ and CH₄ (298 K) in a reversible manner. In regard to the adsorption of N₂ by Zn(2-Mehba), there appears to be an unusual temperature dependence for the uptake of the gas such that when the temperature is increased from 77 to 298 K the uptake of N₂ increases. The relatively narrow channels of Zn(2,6-Me₂hba) are too small to allow the uptake of N₂ and CH₄, but H₂ molecules can be adsorbed. A pronounced step at elevated pressures in CO₂ and N₂O isotherms for Zn(2,6-Me₂hba) is noted. Calculations indicate that rotation of phenolate rings leads to a change in the available intraframework space during CO₂ dosing.

An insight into clustering of halogenated anesthetics molecules in metal-organic frameworks: Evidence of adsorbate self-association in micropores

In order to better understand the adsorption of volatile halogenated anesthetics on metal organic frameworks (MOFs), sevoflurane vapor adsorption experiments were performed on commercial MOF-177 at different temperatures. Due to the surface homogeneity of such an adsorbent, arising from its almost unimodal pore size distribution and the absence of specific, coordinatively unsaturated adsorption active sites, sevoflurane adsorption isotherms exhibited a peculiar deviation from the Langmuirian behavior. Consequently, they show a "kink" at a specific pressure that increases with increasing equilibrium temperature. Successful modeling of such data by means of the Talu-Meunier equation confirmed clustering of adsorbate molecules inside adsorbent micropores, similarly to water vapor adsorption on activated carbon, which may play an important role when designing a system using MOFs as the potential adsorbents for capturing anesthetics.

Fast screening of porous materials for noble gas adsorption and separation: a classical density functional approach

The design and screening of porous materials for noble gas adsorption and separation are an important issue in the production and utilization of gases. The conventional method to do this is via molecular simulation. In this work, we introduced a classical density functional theory (CDFT) to replace molecular simulation because CDFT is more efficient. A molecular dynamics (MD)/CDFT combined method was proposed to consider the flexibility of the adsorbent. The theory was first examined by comparing it to reported experiments and simulations. Then, the theory was applied to determine the most favorable adsorbents for noble gas adsorption/separation from 4764 real adsorbents and 1200 hypothetical adsorbents. A series of favorable adsorbents was identified, and some of them seemed promising. The macroscopic adsorption isotherms and microscopic density profiles of the most favorable adsorbents were examined, and the adsorption mechanisms were revealed. The specific separation of Kr/Xe was examined, and two of the adsorbents showed higher adsorption efficiency than shown in previously reported data.

Porous dipeptide crystals as volatile-drug vessels

Anesthetic vapors find temporary hospitality in porous dipeptide crystals, which behave as biologically friendly hosts and carriers.