Blankets at birth: Transitional objects: Commentary on “The growth of cognition: Free energy minimization and the embryogenesis of cortical computation” by Wright and Bourke

Birth is accompanied by a complete reset of metabolic flows in the neonate, challenging the brain to fulfill the basic needs of life through action – breathing, feeding, crying. The perinatal period is fundamentally a transitional one, such that the basic conditions for thermodynamic self-regulation are re-established ex utero. Wright and Bourke lay out the core tenants of these conditions [1]; the emergence of regularities in cortical geometry and activity that allow “crisp” states. Before this can occur – in the immediate perinatal phase – electrical recordings of neonatal cortex suggest it passes through a highly critical regime - a phase transition - with disordered statistical fingerprints. The resolution of this state is a necessary condition for the more stable metabolic conditions that support the conjectures of Wright and Bourke.     

Synthesis and structural characterization of (η5-Dp)Ru(PPh3)2H (Dp = C8H9−, 1,2-dihydropentalenyl)

Transition Metal Chemistry - (η5-Dp)Ru(PPh3)2H (Dp?=?C8H9?, 1,2-dihydropentalenyl) was synthesized in 90% yield by reaction of (η5-Dp)Ru(PPh3)2Cl with sodium formate....     

Higher dimensional Apollonian packings,revisited

The Apollonian circle and sphere packings are well known objects that have attracted the attention of mathematicians throughout the ages. The historically natural generalization of the procedure for generating the packing breaks down in higher dimensions, as it leads to overlapping hyperspheres. There is, however, an alternative interpretation that allows one to extend the concept to higher dimensions and in a unique way. For relatively small dimensions (2 through at least 8), those packings can be thought of as ample cones for classes of K3 surfaces. We describe the packings in some detail for dimensions 4 (with plenty of pictures), 5, and 6.     

Chemoselective vinylation of aminophenols with acetylene catalyzed by sodium aminophenolates in aqueous DMSO

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Electrochemical sensing of heavy metals in biological media: A review

Trace metals are required in the body as they play a significant role in several biochemical processes. Moreover, certain heavy metals are beneficial at appropriate levels. Copper (Cu), for example, is essential for red blood cell formation, bone strength, and infant growth. Despite these fundamental roles, Cu can become toxic at high levels. Other heavy metals such as lead (Pb), cadmium (Cd), manganese (Mn), and mercury (Hg), have been identified to cause acute and chronic health complications. For these reasons, rapid, real-time quantification of such metals in biological media is of interest to improving human health outcomes. Electrochemical methods offer numerous advantages, such as portability, capability to be miniaturized, low cost, and ease-of-use. In this review, we examine recent developments in electrochemical sensing for the detection of heavy metals in biological media. To meet the requirements for inclusion in this review, the electrochemical sensor must have been evaluated in biological media (blood, serum, sweat, saliva, urine, brain tissue/cells). Several applications are explored to examine recent advancements in electrochemical sensing within these matrices. Addressing the challenges through materials, device, and system innovations, it is expected that electrochemical sensing of heavy metals in biological media will facilitate future diagnoses and treatments in healthcare.     

The Reaction of Cs2[Tc(NO)F5] with BF3 in Acetonitrile: Formation and Structure of [{Tc(NO)(CH3CN)4}2(μ‐F)](BF4)3

The deep blue, paramagnetic Cs₂[Tc^II(NO)F₅] is formed during reactions of pertechnetate, acetohydroxamic acid, and CsF in aqueous HF. A reaction of Cs₂[Tc(NO)F₅] with BF₃ · MeOH in acetonitrile gives yellow blocks of the fluorido‐bridged dimer [{Tc^I(NO)(CH₃CN)₄}₂F](BF₄)₃. The compound is stable as solid and in acetonitrile solutions. The complex cation contains a bent μ‐F^– ligand and two linear nitrosyl groups.     

Chromatographic separation of thulium from erbium for neutron capture cross section measurements—Part I: Trace scale optimization of ion chromatography method with various complexing agents

The impact of various ion chromatography parameters on the separation of trace amounts of thulium from erbium was examined to address the need for the preparation of a ¹⁷¹Tm target for neutron capture cross section measurements. The following optimal operation parameters for analytical scale separations with cation exchange resin were established based on a modified separation resolution: 0.046 M α-HIB^? as eluent with a flow rate of 1.2 mL min^?1 at 25 °C. Different carboxylic acids with varying pH were also investigated, which reaffirmed the use of α-hydroxyisobutyrate as the most suitable complexant for the separation of these neighboring lanthanides.     

Poly(Pyridinium Salt)s Containing 2,7-Diamino-9,9′-Dioctylfluorene Moieties with Various Organic Counterions Exhibiting Both Lyotropic Liquid-Crystalline and Light-Emitting Properties

A series of poly(pyridinium salt)s-fluorene main-chain ionic polymers with various organic counterions were synthesized by using ring-transmutation polymerization and metathesis reactions. Their chemical structures were characterized by Fourier Transform Infrared (FTIR), proton (¹H), and fluorine 19 (¹⁹F) nuclear magnetic resonance (NMR) spectrometers. These polymers showed a number-average molecular weight (M_ns) between 96.5 and 107.8 kg/mol and polydispersity index (PDI) in the range of 1.12–1.88. They exhibited fully-grown lyotropic phases in polar protic and aprotic solvents at different critical concentrations. Small-angle X-ray scattering for one polymer example indicates lyotropic structure formation for 60–80% solvent fraction. A lyotropic smectic phase contains 10 nm polymer platelets connected by tie molecules. The structure also incorporates a square packing motif within platelets. Thermal properties of polymers were affected by the size of counterions as determined by differential scanning calorimetry and thermogravimetric analysis measurements. Their ultraviolet-visible (UV-Vis) absorption spectra in different organic solvents were essentially identical, indicating that the closely spaced π-π* transitions occurred in their conjugated polymer structures. In contrast, the emission spectra of polymers exhibited a positive solvatochromism on changing the polarity of solvents. They emitted green lights in both polar and nonpolar organic solvents and showed blue light in the film-states, but their λ_em peaks were dependent on the size of the counterions. They formed aggregates in polar aprotic and protic solvents with the addition of water (v/v, 0–90%), and their λ_em peaks were blue shifted.