In Situ Measurements of Strains in Composite Battery Electrodes during Electrochemical Cycling

The cyclic stress in lithium-ion battery electrodes induced by repeated charge and discharge cycles causes electrode degradation and fracture, resulting in reduced battery performance and lifetime. To investigate electrode mechanics as a function of electrochemical cycling, we utilize digital image correlation (DIC) to measure the strains that develop in lithium-ion battery electrodes during lithiation and delithiation processes. A composite graphite electrode is cycled galvanostatically (with constant current) in a custom battery cell while optical images of the electrode surface are captured in situ. The strain in the electrode is computed using an in-house DIC code. On average, an unconstrained composite graphite electrode expands 1.41 % during lithiation and contracts 1.33 % during delithiation. These strain values compare favorably with predictions based on the elastic properties of the composite electrode and the expansion of graphite-lithium intercalation compounds (G-LICs). The establishment of this experimental protocol will enable future studies of the relationship between electrode mechanics and battery performance.     

THE HYDROLYSIS OF PHOSPHATIDYLCHOLINE BY PHOSPHOLIPASE A2 IN MICROEMULSION AS MICROREACTOR

Phosphotipase A₂ (PLA₂) was used to hydrolyze phosphatidylcholine (PC) in microemulsions. Phase diagrams were constructed for mixtures of alcohols (C₂-C₆), medium chain triglycerides (tricaprylin, TC) or vegetable oils, PC and water, and areas corresponding to isotropic systems were identified. The PC hydrolysis was carried out with high yields at various PC/(TC+alcohol) compositions within the areas of isotropic systems at increasing amounts of solubilized water.

The initial reaction rates depended on the aggregation state of the PC (size and nature of microemulsion structures), as well as on temperature and mode of calcium addition.

At low enzyme concentrations, hydrolysis was preceded by a “lag phase” followed by an abrupt increase in rate. By contrast, no latency was observed at higher PLA₂ PC ratios and the rate was significantly higher.

The easy access of the enzyme to the substrate in the curved phospholipid-containing microemulsion particles facilitate activation of the enzyme and “pushes” the reaction to completion. Hence, these microemulsions can serve as microreactors for the enzymatic high yield hydrolysis.     

Synthetic and structural comparisons of bismuth(III) carboxylates synthesised under solvent-free and reflux conditions

Two synthetic approaches to the formation of bismuth(III) carboxylates have been explored and compared. Ph(3)Bi was reacted with a series of carboxylic acids (RCO(2)H) of varying pK(a) and functionality (R = PhCH[double bond, length as m-dash]CH, o-MeOC(6)H(4), m-MeOC(6)H(4), o-H(2)NC(6)H, o-O(2)NC(6)H(4), p-O(2)NC(6)H(4), 2-(C(5)H(4)N)) under reflux conditions in toluene and solvent-free. The thermochemical profiles of the solvent-free reactions were also studied by DSC-TGA. All reactions produced the tri-substituted bismuth carboxylates in comparable yields and purity with the exceptions of picolinic acid and p-nitrobenzoic acid. 2-Picolinic acid exclusively formed the di-substituted complex, [PhBi(2-(C(5)H(4)N)CO(2))(2)](4), by both methods, while p-nitrobenzoic acid gave the tri-substituted complex through reflux and the di-substituted complex under solvent-free conditions. Two of the complexes were structurally authenticated by single crystal X-ray diffraction: [PhBi(2-(C(5)H(4)N)CO(2))(2)](4) is tetrameric formed through five membered chelate rings involving the pyridyl N and O(-C) rather than the less stable carboxylate (-CO(2)) chelates, while [Bi(o-MeOC(6)H(4)CO(2))(3)](infinity), is a polymer in which dimeric units, constructed around two chelating and one unsymmetrical bridging carboxylate on each Bi centre, are then joined together through longer intermolecular Bi-O bridging bonds.     

Functionalised β-diketonate polynuclear lanthanoid hydroxo clusters: Synthesis,characterisation, and magnetic properties

The controlled hydrolysis of lanthanoid trichloride hexahydrate (Ln = Nd, Eu, Ho) in methanol with the β-diketone ligands dibenzoylmethane and 1,3-bis(4-ethoxyphenyl)propane-1,3-dione yielded tetranuclear and pentanuclear hydroxo clusters for Eu and Ho. In contrast, performing the reaction in the presence of 1,3-bis(4-methoxyphenyl)propane-1,3-dione yielded a mononuclear complex for Nd. The compounds were structurally characterised by means of single crystal X-ray diffraction, showing that the increased bulkiness of the ligand due to the ethoxy functionalities does not affect the capability of the diketonate to stabilize the cluster core. Variable temperature dc susceptibility magnetic measurements were made on the clusters and were indicative of very weak to zero antiferromagnetic, intra-cluster coupling. Variable frequency ac data recorded at low temperatures did not show any evidence for single molecule magnet (SMM) behaviour, unlike the recent reported case of the analogue [Dy₅(OH)₅(Ph₂acac)₁₀], where Ph₂acac⁻ is the dibenzoylmethanide ligand.     

No Preferred Reference Frame at the Foundation of Quantum Mechanics

Quantum information theorists have created axiomatic reconstructions of quantum mechanics (QM) that are very successful at identifying precisely what distinguishes quantum probability theory from classical and more general probability theories in terms of information-theoretic principles. Herein, we show how one such principle, Information Invariance and Continuity, at the foundation of those axiomatic reconstructions, maps to “no preferred reference frame” (NPRF, aka “the relativity principle”) as it pertains to the invariant measurement of Planck’s constant h for Stern-Gerlach (SG) spin measurements. This is in exact analogy to the relativity principle as it pertains to the invariant measurement of the speed of light c at the foundation of special relativity (SR). Essentially, quantum information theorists have extended Einstein’s use of NPRF from the boost invariance of measurements of c to include the SO(3) invariance of measurements of h between different reference frames of mutually complementary spin measurements via the principle of Information Invariance and Continuity. Consequently, the “mystery” of the Bell states is understood to result from conservation per Information Invariance and Continuity between different reference frames of mutually complementary qubit measurements, and this maps to conservation per NPRF in spacetime. If one falsely conflates the relativity principle with the classical theory of SR, then it may seem impossible that the relativity principle resides at the foundation of non-relativisitic QM. In fact, there is nothing inherently classical or quantum about NPRF. Thus, the axiomatic reconstructions of QM have succeeded in producing a principle account of QM that reveals as much about Nature as the postulates of SR.     

Tailor-made thermoplastic elastomers: customisable materials via modulation of molecular weight distributions

The ability to change polymer properties has in the past largely been a factor of modulating the molecular weight, molecular weight distribution breadth, crosslinking, or branching. The use of controlled MWD shape has recently emerged as a promising avenue towards modifying polymer properties. Taking advantage of molecular weight distribution shape, we report a simple and efficient approach for tuning material properties in polystyrene-block-polyisoprene-block-polystyrene (SIS) thermoplastic elastomers (TPEs). We find that the skew of the MWD function governs tensile properties and can be used as a handle to predictably vary polymer toughness while reducing energy dissipation.

Taking advantage of molecular weight distributions shape, we report a simple and efficient approach for predictably tuning material properties for thermoplastic elastomers.     

Über die Kondensation von Isobutyrformaldol mit Malonsäure

Ohne ZusammenfassungEs sei mir noch gestattet, dem Herrn Hofrate Lieben sowie Herrn Dr. Pomeranz für die mir im Laufe der Arbeit erteilten Ratschläge meinen besten Dank auszusprechen.