Simple bifunctional salts for synthesising block copolymers from anhydrides/epoxides and vinyl acetate.

Herein, we report the first synthesis of poly(ester--vinyl acetate) epoxide/anhydride ring-opening copolymerisation and reversible addition-fragmentation chain transfer polymerisation. This was achieved using simple, robust and bifunctional alkali metal carboxylates featuring a xanthate unit.

Ring-opening polymerization of ε-caprolactone with a macrocyclic tetracarbene indium complex.

The first chiral tetracarbene indium(III) complexes have been synthesized by employing a rigid dianionic macrocyclic tetra-NHC ligand. The macrocyclic indium tetra-NHC bromide and ethoxide complexes are structurally similar to analagous salen complexes. The indium ethoxide complex effectively promotes living ring-opening polymerization of ε-caprolactone at room temperature.

Simple divalent metal salts as robust and efficient initiators for the ring-opening polymerisation of -lactide.

Simple divalent metal benzoxides are reported as robust and efficient catalysts for lactide (LA) polymerisation. Following a "pre-stir" step to aid solubility, the best performing catalyst, Zn(OBn), gave quantitative monomer conversion in just 30 seconds and performed well under industrially relevant settings with high monomer loadings, bulk polymerisation conditions and non-anhydrous conditions using technical grade LA.

Fluctuations of thermal variables investigated by cross-correlation function.

Fluctuations in conjugate thermodynamic variables are studied using the cross-correlation function. A new procedure is given enabling the derivation of fluctuation formulas for a system in equilibrium. Specifically, the cross-correlation function between heat and temperature is employed for thermal variables.

Unlocking the Potential of Polythioesters.

As the demand for sustainable polymers increases, most research efforts have focused on polyesters, which can be bioderived and biodegradable. Yet analogous polythioesters, where one of the oxygen atoms has been replaced by a sulfur atom, remain a relatively untapped source of potential. The incorporation of sulfur allows the polymer to exhibit a wide range of favorable properties, such as thermal resistance, degradability, and high refractive index.

Cooperative heterometallic catalysts: balancing activity and control in PCL--PLA copolymer synthesis.

Heterometallic cooperativity is gaining momentum in cyclic ester ring-opening polymerisation, yet remains surprisingly underexplored in their block copolymerisations. Here, we report the first homogeneous heterometallic "ate" catalysts for poly(ε-caprolactone)-poly(lactic acid) block copolymers, showcasing the substantial differences in the polymer structures observed upon exchanging Zn for Mg or Ca.

Exploiting Multimetallic Cooperativity in the Ring-Opening Polymerization of Cyclic Esters and Ethers.

The use of multimetallic complexes is a rapidly advancing route to enhance catalyst performance in the ring-opening polymerization of cyclic esters and ethers. Multimetallic catalysts often outperform their monometallic analogues in terms of reactivity and/or polymerization control, and these improvements are typically attributed to "multimetallic cooperativity". Yet the origins of multimetallic cooperativity often remain unclear.

NacNac-zinc-pyridonate mediated ε-caprolactone ROP.

Herein we report the synthesis, isolation and polymerisation activity of two new zinc compounds based on a 2,6-diisopropylphenyl (Dipp) β-diiminate (NacNac) ligand framework with zinc also ligated by an amidate (2-pyridonate or 6-methyl-2-pyridonate) unit. The compounds crystallised as either monomeric (6-Me-2-pyridonate derivative) or dimeric (2-pyridonate) species, although both were found to be monomeric in solution H DOSY NMR spectroscopy, which was supported by DFT calculations. These observations suggest that both complexes initiate ring-opening polymerisation (ROP) through a single-site monometallic mechanism.

Alternative splicing and heparan sulfation converge on neurexin-1 to control glutamatergic transmission and autism-related behaviors.

Neurexin synaptic organizing proteins are central to a genetic risk pathway in neuropsychiatric disorders. Neurexins also exemplify molecular diversity in the brain, with over a thousand alternatively spliced forms and further structural heterogeneity contributed by heparan sulfate glycan modification. Yet, interactions between these modes of post-transcriptional and post-translational modification have not been studied.

Correction: Main group metal polymerisation catalysts.

Correction for 'Main group metal polymerisation catalysts' by Eszter Fazekas , , 2022, , 8793-8814, https://doi.org/10.1039/D2CS00048B.

Main group metal polymerisation catalysts.

With sustainability at the forefront of current polymerisation research, the typically earth-abundant, inexpensive and low-toxicity main group metals are attractive candidates for catalysis. Main group metals have been exploited in a broad range of polymerisations, ranging from classical alkene polymerisation to the synthesis of new bio-derived and degradable polyesters and polycarbonates ring-opening polymerisation and ring-opening copolymerisation. This tutorial review highlights efficient polymerisation catalysts based on Group 1, Group 2, Zn and Group 13 metals.

Low Formaldehyde Binders for Mineral Wool Insulation: A Review.

Insulating materials are ubiquitous in a built environment and play a critical role in reducing the energy consumed to maintain habitable indoor environments. Mineral wool insulation (MWI) products, including glass, stone, and slag variants, are the most widely used class of insulating materials in Europe and account for more than 50% of the total market by volume. MWI typically consists of two key components: a mesh of inorganic fibers that are several micrometers in diameter, and an organic thermosetting adhesive commonly referred to as the "binder.

Understanding temperature-modulated calorimetry through studies of a model system.

Temperature modulated calorimetry is widely used but still raises some fundamental questions. In this paper we study a model system as a test sample to address some of them. The model has a nontrivial spectrum of relaxation times.

Salt additives as activity boosters: a simple strategy to access heterometallic cooperativity in lactide polymerisation.

Inorganic salt additives can activate carbonyl groups towards organic addition reactions. Here, we translate this concept to ring-opening polymerisation for the first time, generating heterometallic ProPhenol catalysts , which show similar activity enhancements to pre-formed heterometallic complexes. Extremely high activities are observed, with K/Mg and K/Ca combinations converting >85 eq.

The Hebb Synapse Before Hebb: Theories of Synaptic Function in Learning and Memory Before , With a Discussion of the Long-Lost Synaptic Theory of William McDougall.

Since the work of Semon was rediscovered by Schacter in 1978, there has been a renewed interest is searching for the "engram" as the locus of memory in the brain and Hebb's cell assembly has been equated with Semon's engram. There have been many theories of memory involving some concept of synaptic change, culminating in the "Hebb Synapse" theory in 1949. However, Hebb said that the idea that any two cells or systems of cells that are repeatedly active at the same time will tend to become "associated," was not his idea, but an old one.

Combining alkali metals and zinc to harness heterometallic cooperativity in cyclic ester ring-opening polymerisation.

Heterometallic cooperativity is an emerging strategy to elevate polymerisation catalyst performance. Here, we report the first heterotrimetallic Na/Zn and K/Zn complexes supported by a ProPhenol ligand, which deliver "best of both" in cyclic ester ring-opening polymerisation, combining the outstanding activity (Na/K) and good control (Zn) of homometallic analogues. Detailed NMR studies and density-functional theory calculations suggest that the Na/Zn and K/Zn complexes retain their heterometallic structures in the solution-state.

Advances in heterometallic ring-opening (co)polymerisation catalysis.

Truly sustainable plastics require renewable feedstocks coupled with efficient production and end-of-life degradation/recycling processes. Some of the most useful degradable materials are aliphatic polyesters, polycarbonates and polyamides, which are often prepared via ring-opening (co)polymerisation (RO(CO)P) using an organometallic catalyst. While there has been extensive research into ligand development, heterometallic cooperativity offers an equally promising yet underexplored strategy to improve catalyst performance, as heterometallic catalysts often exhibit significant activity and selectivity enhancements compared to their homometallic counterparts.

Melting transition of oriented Li-DNA fibers submerged in ethanol solutions.

The melting transition of Li-DNA fibers immersed in ethanol-water solutions has been studied using calorimetry and neutron diffraction techniques. The data have been analyzed using the Peyrard-Bishop-Dauxois model to determine the strengths of the intra- and inter-base pair potentials. The data and analysis show that the potentials are weaker than those for DNA in water.

Cooperative Heterometallic Catalysts for Lactide Ring-Opening Polymerization: Combining Aluminum with Divalent Metals.

While homometallic (salen)Al catalysts display excellent performance in lactide ring-opening polymerization (ROP), heterometallic (salen)Al complexes have yet to be reported. Herein, we describe four heterobimetallic (salen)Al catalysts and show that the choice of the heterometal is key. Cooperative Al/Mg and Al/Zn combinations improved the catalyst activity by a factor of up to 11 compared to the mono-Al analogue, whereas the mono-Mg and mono-Zn analogues were completely inactive.

Memory effects in glasses: Insights into the thermodynamics of out-of-equilibrium systems revealed by a simple model of the Kovacs effect.

Glasses are interesting materials because they allow us to explore the puzzling properties of out-of-equilibrium systems. One of them is the Kovacs effect in which a glass, brought to an out-of-equilibrium state in which all its thermodynamic variables are identical to those of an equilibrium state, nevertheless evolves, showing a hump in some global variable before the thermodynamic variables come back to their starting point. We show that a simple three-state system is sufficient to study this phenomenon using numerical integrations and exact analytical calculations.

Treatment of Pain in Keloids Using Only a Long-Pulsed 1064 nm Nd:YAG Laser.

Background And Objective: Keloids are benign lesions arising from overproduction of the extracellular matrix and abnormal collagen deposition by dermal fibroblasts. This altered wound healing typically occurs in response to dermal trauma. Keloid treatment poses a challenge due to the variable nature of treatment response, which can be affected by the size, appearance, and associated symptoms of erythema, pruritus, and pain.

Long-term Facial and Body Hair Removal With a Combined Radiofrequency and Optical Home-Use Device for All Skin Types.

Objectives: To evaluate long term effectiveness and safety with the use of a combined radiofrequency and optical home hair removal device in all skin types and over both facial and body areas.

Methods: A combined intense pulsed light (IPL) and radiofrequency (RF) home device was used for hair removal. Two separate study designs were evaluated.

Iron Half Salen Catalysts for Atom Transfer Radical and Ring-Opening Polymerizations.

A series of monometallic pentacoordinate Fe chloride complexes have been prepared and characterized by high-resolution mass spectrometry and elemental analysis. X-ray diffraction analysis showed that the bis-chelated Fe complexes bear distorted trigonal bipyramidal geometries. The air- and moisture-stable Fe complexes were screened as mediators in the reverse atom transfer radical polymerization (ATRP) of styrene and methyl methacrylate.

Erratum: Heterodinuclear zinc and magnesium catalysts for epoxide/CO ring opening copolymerizations.

[This corrects the article DOI: 10.1039/C9SC00385A.].

DFT and MD Studies of Formaldehyde-Derived DNA Adducts: Molecular-Level Insights into the Differential Mispairing Potentials of the Adenine, Cytosine, and Guanine Lesions.

4-(Methylnitrosamino)-1-(3-pyridyl)-1-butanone is a potent nicotine-based carcinogen that generates many DNA lesions, including the HOCH-C, HOCH-G, and HOCH-A hydroxymethyl adducts. Despite all lesions containing an altered exocyclic amino group, which allows the hydroxymethyl group to be directed away from the Watson-Crick binding face, only the most persistent adenine adduct is mutagenic. As a first step toward understanding this differential mutagenicity, density functional theory (DFT) and molecular dynamics (MD) simulations were used to gain atomic-level structural details of these DNA damage products.