Sub-cortical and brainstem sites associated with chemo-stimulated increases in ventilation in humans

We investigated the neural basis for spontaneous chemo-stimulated increases in ventilation in awake, healthy humans. Blood oxygen level dependent (BOLD) functional MRI was performed in nine healthy subjects using T2weighted echo planar imaging. Brain volumes (52 transverse slices, cortex to high spinal cord) were acquired every 3.9 s. The 30 min paradigm consisted of six, 5-min cycles, each cycle comprising 45 s of hypoxic-isocapnia, 45 s of isooxic-hypercapnia and 45 s of hypoxic-hypercapnia, with 55 s of non-stimulatory hyperoxic-isocapnia (control) separating each stimulus period. Ventilation was significantly (p < 0.001) increased during hypoxic-isocapnia, isooxic-hypercapnia and hypoxic-hypercapnia (17.0, 13.8, 24.9 L/min respectively) vs. control (8.4 L/min) and was associated with significant (p < 0.05, corrected for multiple comparisons) signal increases within a bilateral network that included the basal ganglia, thalamus, red nucleus, cerebellum, parietal cortex, cingulate and superior mid pons. The neuroanatomical structures identified provide evidence for the spontaneous control of breathing to be mediated by higher brain centres, as well as respiratory nuclei in the brainstem

The adhesive properties of pyridine-terminated self-assembled monolayers

The atomic force microscopy (AFM) adhesion force behaviour and contact angle titration behaviour of self-assembled monolayers (SAMs) presenting surface pyridine and substituted pyridine moieties has been investigated as a function of pH and electrolyte concentration. The pKas of the pyridine moieties were modified through the incorporation of fluorine, chlorine and bromine substituents in the pyridyl ring. Contact angle titration and AFM adhesion force measurements were performed using aqueous phosphate buffered saline solutions over the pH range 3–9, and at concentrations of 150 mM and 0.1 mM. AFM adhesion force measurements were performed using a clean Si3N4 pyramidal-tipped AFM cantilever

One-step fabrication of hollow-channel gold nanoflowers with excellent catalytic performance and large single-particle SERS activity.

Hollow metallic nanostructures have shown potential in various applications including catalysis, drug delivery and phototherapy, owing to their large surface areas, reduced net density, and unique optical properties. In this study, novel hollow gold nanoflowers (HAuNFs) consisting of an open hollow channel in the center and multiple branches/tips on the outer surface are fabricated for the first time, via a facile one-step synthesis using an auto-degradable nanofiber as a bifunctional template. The one-dimensional (1D) nanofiber acts as both a threading template as well as a promoter of the anisotropic growth of the gold crystal, the combination of which leads to the formation of HAuNFs with a hollow channel and nanospikes. The synergy of favorable structural/surface features, including sharp edges, open cavity and high-index facets, provides our HAuNFs with excellent catalytic performance (activity and cycling stability) coupled with large single-particle SERS activity (including ∼30 times of activity in ethanol electro-oxidation and ∼40 times of single-particle SERS intensity, benchmarked against similar-sized solid gold nanospheres with smooth surfaces, as well as retaining 86.7% of the initial catalytic activity after 500 cycles in ethanol electro-oxidation). This innovative synthesis gives a nanostructure of the geometry distinct from the template and is extendable to fabricating other systems for example, hollow-channel silver nanoflowers (HAgNFs). It thus provides an insight into the design of hollow nanostructures via template methods, and offers a versatile synthetic strategy for diverse metal nanomaterials suited for a broad range of applications

Sub‐nanometer thick gold nanosheets as highly efficient catalysts

2D metal nanomaterials offer exciting prospects in terms of their properties and functions. However, the ambient aqueous synthesis of atomically‐thin, 2D metallic nanomaterials represents a significant challenge. Herein, freestanding and atomically‐thin gold nanosheets with a thickness of only 0.47 nm (two atomic layers thick) are synthesized via a one‐step aqueous approach at 20 °C, using methyl orange as a confining agent. Owing to the high surface‐area‐to‐volume ratio, abundance of unsaturated atoms exposed on the surface and large interfacial areas arising from their ultrathin 2D nature, the as‐prepared Au nanosheets demonstrate excellent catalysis performance in the model reaction of 4‐nitrophenol reduction, and remarkable peroxidase‐mimicking activity, which enables a highly sensitive colorimetric sensing of H2O2 with a detection limit of 0.11 × 10−6 m. This work represents the first fabrication of freestanding 2D gold with a sub‐nanometer thickness, opens up an innovative pathway toward atomically‐thin metal nanomaterials that can serve as model systems for inspiring fundamental advances in materials science, and holds potential across a wide region of applications

Sub‐nanometer thick gold nanosheets: sub‐nanometer thick gold nanosheets as highly efficient catalysts (Adv. Sci. 21/2019)

In article number 1900911, Stephen D. Evans and co‐workers develop an ambient aqueous synthesis for preparing atomically‐thin gold nanosheets (termed gold nanoseaweed, AuNSW, because of its morphology, color and aqueous growth). These AuNSWs represent the first free‐standing 2D gold with a sub‐nanometer thickness (0.47 nm, e.g., two atomic layers thick), and exhibit excellent catalysis performance in the model reaction of 4‐nitrophenol reduction, as well as remarkable peroxidase‐mimicking activity

Sub‐nanometer thick gold nanosheets: sub‐nanometer thick gold nanosheets as highly efficient catalysts (Adv. Sci. 21/2019)

In article number 1900911, Stephen D. Evans and co‐workers develop an ambient aqueous synthesis for preparing atomically‐thin gold nanosheets (termed gold nanoseaweed, AuNSW, because of its morphology, color and aqueous growth). These AuNSWs represent the first free‐standing 2D gold with a sub‐nanometer thickness (0.47 nm, e.g., two atomic layers thick), and exhibit excellent catalysis performance in the model reaction of 4‐nitrophenol reduction, as well as remarkable peroxidase‐mimicking activity

The pH-dependent adhesion of nanoparticles to self-assembled monolayers on gold

The effect of pH on the adhesion of silica and polystyrene latex nanoparticles, presenting hydroxyl and carboxylic acid surface chemistries respectively, to self-assembled monolayers (SAMs) has been investigated. The SAMs studied were 1-dodecanethiol, 11-mercaptoundecanoic acid and an original pyridine-terminated SAM. Adhesion of nanoparticles to the SAMs was found to decrease with increasing pH due to increased repulsive forces between surfaces, as a result of the deprotonation of surface moieties on the nanoparticles. A range of surface morphologies for the adsorbed nanoparticles was observed for the systems studied

Variant connective tissue (joint hypermobility) and its relevance to depression and anxiety in adolescents: a cohort-based case-control study

Objective: To test whether variant connective tissue structure, as indicated by the presence of joint hypermobility, poses a developmental risk for mood disorders in adolescence. Design: Cohort-based case-control study. Setting: Data from the Avon Longitudinal Study of Parents and Children (ALSPAC) were interrogated. Participants: 6105 children of the ALSPAC cohort at age 14 years old, of whom 3803 also were assessed when aged 18 years. Main outcome measures: In a risk analysis, we examined the relationship between generalised joint hypermobility (GJH) at age 14 years with psychiatric symptoms at age 18 years. In an association analysis, we examined the relationship between presence of symptomatic joint hypermobility syndrome (JHS) and International Classification of Diseases (ICD-10) indication of depression and anxiety (Clinical Interview Schedule Revised [CIS-R], Anxiety Sensitivity Index [ASI]) at age 18 years. Results: GJH was more common in females (n=856, 28%) compared to males (n=319, 11%; OR 3.20 (95% CI 2.78 to 3.68); P<0.001). In males only, GJH at age 14 years was associated with depression at 18 years (OR 2.10 (95%CI 1.17 to 3.76); P=0.013). An index of basal physiological arousal, elevated resting heart rate, mediated this effect. Across genders, the diagnosis of JHS at age 18 years was associated with the presence of depressive disorder (adjusted OR 3.53 (95%CI 1.67 to 7.40); P=0.001), anxiety disorder (adjusted OR 3.14 (95% CI 1.52 to 6.46); P=0.002), level of anxiety (B=8.08, t(3278)=3.95; P<0.001), and degree of psychiatric symptomatology (B=5.89, t(3441)=0.093; p<0.001). Conclusions: Variant collagen, indexed by joint hypermobility, is linked to the emergence of depression and anxiety in adolescence, an effect mediated by autonomic factors in males. Recognition of this association may motivate further evaluation, screening, and interventions to mitigate development of psychiatric disorders and improve health outcomes

Towards compartmentalized photocatalysis: multihaem proteins as transmembrane molecular electron conduits.

The high quantum efficiency of natural photosynthesis has inspired chemists for solar fuel synthesis. In photosynthesis, charge recombination in photosystems is minimized by efficient charge separation across the thylakoid membrane. Building on our previous bioelectrochemical studies of electron transfer between a light-harvesting nanoparticle (LHNP) and the decahaem subunit MtrC, we demonstrate photo-induced electron transfer through the full transmembrane MtrCAB complex in liposome membranes. Successful photoelectron transfer is demonstrated by the decomposition of a redox dye, Reactive Red 120 (RR120), encapsulated in MtrCAB proteoliposomes. The photoreduction rates are found to be dependent on the identity of the external LHNPs, specifically, dye-sensitized TiO2, amorphous carbon dots (a-CD) and graphitic carbon dots with core nitrogen doping (g-N-CDs). Agglomeration or aggregation of TiO2 NPs likely reduces the kinetics of RR120 reductive decomposition. In contrast, with the dispersed a-CD and g-N-CDs, the kinetics of the RR120 reductive decomposition are observed to be faster with the MtrCAB proteoliposomes and we propose that this is due to enhancement in the charge-separated state. Thus, we show a proof-of-concept for using MtrCAB as a lipid membrane-spanning building block for compartmentalised photocatalysis that mimics photosynthesis. Future work is focused on incorporation of fuel generating redox catalysts in the MtrCAB proteoliposome lumen.This work was supported by the BBSRC (DTP studentship 1827308; grants BB/ K009753/1, BB/K010220/1 and BB/K009885/1) and the Engineering and Physical Sciences Research Council (PhD studentship 1307196)

Observation of compositional domains within individual copper indium sulfide quantum dots

The origin of photoluminescence in copper indium sulfide (CIS) quantum dots (Qdots) has previously been ascribed to a donor-acceptor pair (DAP) recombination, with a crystal lattice defect implicated as the origin of the donor state. In this study, electron energy-loss spectroscopy (EELS) was used to observe defect-rich compositional domains within individual CIS Qdots, supporting a model of defect-state-mediated photoluminescence for these particles, and identifying them as an ideal model system for future study of lattice defects on Qdot properties