Research Development on Sodium-Ion Batteries

Two major energy-related problems confront the world in the
next 50 years. First, increased worldwide competition for
gradually depleting fossil fuel reserves (derived from past
photosynthesis) will lead to higher costs, both monetarily and politically. Second, atmospheric CO_2 levels are at their highest recorded level since records began. Further increases are predicted to produce large and uncontrollable impacts on the world climate. These projected impacts extend beyond climate to ocean acidification, because the ocean is a major sink for atmospheric CO2.1 Providing a future energy supply that is secure and CO_2-neutral will require switching to nonfossil energy sources such as wind, solar, nuclear, and geothermal energy and developing methods for transforming the energy produced by these new sources into forms that can be stored, transported, and used upon demand.

Frontiers, Opportunities, and Challenges in Biochemical and Chemical Catalysis of CO2 Fixation

Positive electrodes for Li-ion and lithium batteries (also termed “cathodes”) have been under intense scrutiny since the advent of the Li-ion cell in 1991. This is especially true in the past decade. Early on, carbonaceous materials dominated the negative electrode and hence most of the possible improvements in the cell were anticipated at the positive terminal; on the other hand, major developments in negative electrode materials made in the last portion of the decade with the introduction of nanocomposite Sn/C/Co alloys and Si−C composites have demanded higher capacity positive electrodes to match. Much of this was driven by the consumer market for small portable electronic devices. More recently, there has been a growing interest in developing Li−sulfur and Li−air batteries that have the potential for vastly increased capacity and energy density, which is needed to power large-scale systems. These require even more complex assemblies at the positive electrode in order to achieve good properties. This r...

Positive Electrode Materials for Li-Ion and Li-Batteries†

ion step follows the decarboxylation, which is consistent with the deuterium isotopic effects observed for thymine 7-hydroxylase which indicate that an irreversible step (or steps) occurs prior to the C-H bond breaking.395 It has also been shown for prolyl 4-hydroxylase that a substrate-derived radical is generated in the reaction, which is consistent with a rebound mechanism.437 It is important to point out that no oxygen intermediate (i.e., bridged superoxo or oxo-ferryl) has been observed for any R-KGdependent enzyme. This warrants future theoretical and experimental study. A detailed molecular mechanism has been proposed for IPNS based on spectroscopic and crystallographic studies.422 Resting IPNS/FeII is also 6C and thus relatively stable toward dioxygen. Substrate ACV binds directly to FeII IPNS through its thiolate group, providing an open coordination position at the FeII. O2 can then react to form an FeIII-superoxo intermediate. This intermediate is suggested422 to perform the first hydrogen-atom abstraction step and close the â-lactam ring, resulting in the formation of the first water molecule and generating an FeIVdO-II intermediate, which completes the second ringclosure process by hydrogen-atom abstraction forming a thiazolidine ring. Previously proposed mechanisms of ACCO involved direct binding of cosubstrate ascorbate to the iron before O2 as part of the oxygen activation process.438,439 The EPR and ESEEM studies of the NO complex of ACCO suggested a quite different molecular mechanism for ACCO.435 An FeIII-superoxo intermediate is proposed. Whether it is preceded by a 6C f 5C process with substrate binding is presently under study.440 This intermediate is thought to initiate a radical process by single hydrogen-atom abstraction or electron-coupled proton transfer (PT)ion or electron-coupled proton transfer (PT) from the bound amino group. The resulting substrate radical may undergo spontaneous conversion into products. The role of cosubstrate ascorbate is proposed to reduce the toxic peroxo byproduct to water. Alternatively, the two-electron reduction of FeIIIsuperoxo by the cosubstrate ascorbate could result in an FeIVdO-II intermediate which initiates the radical reaction.435 4. Rieske-Type Dioxygenases Biochemical Characterization. The Rieske ironsulfur center is a two iron-two sulfur cluster ([2Fe2S]) which has a 2His (on one iron), 2Cys (on the other iron) coordination environment, instead of the 4Cys present in plant ferredoxins. It plays a key role in the electron transport pathway in membranebound cytochrome complexes as well as in some dioxygenases.441 The latter are mainly comprised of two protein components: a reductase containing flavin and a ferredoxin [2Fe-2S], and a terminal oxygenase containing a Rieske [2Fe-2S] cluster and a non-heme iron active site.442 Except for the recently reported alkene monooxygenase that has a binuclear iron site in its terminal oxygenase,10 most of the Rieske-type oxygenases have a mononuclear iron site, which is believed to be the site of dioxygen activation and substrate oxygenation.442,443 The majority of the Rieske-type mononuclear non-heme oxygenases form a family of enzymes which are aromatic-ring-hydroxylating dioxygenases. These catalyze the regioand stereospecific cis-dihydroxylation of an aromatic ring using dioxygen and NAD(P)H (Table 1). Examples include benzene dioxygenase (BDO, EC 1.14.12.3),444 phthalate dioxygenase (PDO, EC 1.14.12.7),445 toluene dioxygenase (EC 1.14.12.11),446 and naphthalene 1,2-dioxygenase (NDO, EC 1.14.12.12),447 which initiate the aerobic degradation of aromatic compounds in the soil bacteria and are targets for bioengineering in bioremediation. This step is the first step in the pathway that ultimately leads to ring cleavage by the intraand extradiol dioxygenases (sections II.B.2 and II.C.1).443 Besides these bacterial dioxygenases, other Rieske-type mononuclear non-heme oxygenases include anthranilate 1,2-dioxygenase (EC 1.14.12.1),448 which deaminates and decarboxylates the substrate to produce catechol; chlorophenylacetate 3,4-dioxygenase (EC 1.14.2.13),449 which converts substrate to catechol with chloride elimination; and 4-methoxybenzoate O-demethylase (putidamonooxin),450 which catalyzes the conversion of 4-methoxybenzoic acid to 4-hydroxybenzoic acid and formaldehyde. The reductase component is usually a monomer (MW ) 12-15 kDa) and utilizes flavin to mediate ET from the two-electron donor NAD(P)H to the oneelectron acceptor [2Fe-2S] cluster and is specific to each terminal oxygenase; other electron donors do not support efficient oxygenation.442 The crystal structure of phthalate dioxygenase reductase is available.451 The terminal oxygenases are large protein aggregates (MW ) 150-200 kDa) containing either multiples of R subunits (BDO R2, PDO R4) or an equimolar combination of R and â subunits (toluene dioxygenase R2â2, NDO R3â3). The R subunits contain a Rieske [2Fe-2S] cluster and a catalytic non-heme FeII center. â subunits do not seem to be involved in the catalytic function (vide infra). Kinetics. Steady-state kinetic studies coupled with various rapid reaction studies of the partial reactions of PDO allowed Ballou et al. to propose a kinetic scheme (Scheme 15).443 On the basis of steady state 278 Chemical Reviews, 2000, Vol. 100, No. 1 Solomon et al.

Geometric and Electronic Structure/Function Correlations in Non-Heme Iron Enzymes

Cyclometalated phosphine-based pincer complexes: Mechanistic insight in catalysis, coordination, and bond activation

Solution and solid-state molecular structures of Me2Sn(OAc)2 and its hydrolyzate, ([Me2Sn(OAc)]2O)2, by solution and solid-state carbon-13 NMR. X-ray diffraction study of the hydrolyzate

OBJECTIVE--To determine the advantages and disadvantages of endometrial resection and abdominal hysterectomy for the surgical treatment of women with menorrhagia. DESIGN--Randomised study of two treatment groups with a minimum follow up of nine months. SETTING--Royal Berkshire Hospital, Reading. SUBJECTS--51 of 78 menorrhagic women without pelvic pathology who were on the waiting list for abdominal hysterectomy. TREATMENT--Endometrial resection or abdominal hysterectomy (according to randomisation). Endometrial resections were performed by an experienced hysteroscopic surgeon; hysterectomies were performed by two other gynaecological surgeons. MAIN OUTCOME MEASURES--Length of operating time, hospitalisation, recovery; cost of surgery; short term results of endometrial resection. RESULTS--Operating time was shorter for endometrial resection (median 30 (range 20-47) minutes) than for hysterectomy (50 (39-74) minutes). The hospital stay for endometrial resection (median 1 (range 1-3) days) was less than for hysterectomy (7 (5-12) days). Recovery after endometrial resection (median 16 (range 5-62) days) was shorter than after hysterectomy (58 (11-125) days). The cost was 407 pounds for endometrial resection and 1270 pounds for abdominal hysterectomy. Four women (16%) who did not have an acceptable improvement in symptoms after endometrial resection had repeat resections. No woman has required hysterectomy during a mean follow up of one year. CONCLUSION--For women with menorrhagia who have no pelvic pathology endometrial resection is a useful alternative to abdominal hysterectomy, with many short term benefits. Larger numbers and a longer follow up are needed to estimate the incidence of complications and the long term efficacy of endometrial resection.

https://www.bmj.com/content/bmj/303/6814/1362.full.pdf

A randomised trial comparing endometrial resection and abdominal hysterectomy for the treatment of menorrhagia.

Determination de la structure cristalline du complexe [IrH 2 (methyl-8 quinoleine)(PPh 3 ) 2 ]SbF 6 . Developpement de la mesure de la force de l'interaction pont et utilisation pour systematiser les donnees sur 17 structures apparentees

Inter- vs. intramolecular C-H activation: a C-H-Ir bridge in [IrH2(8-methylquinoline)L2]BF4 and a C-H+M→C-M-H reaction trajectory

Activation of coordinated carbon monoxide toward alkyl and aryl migration (carbon monoxide insertion) by molecular Lewis acids and x-ray structure of the reactive intermediate

Inter- vs. intramolecular carbon-hydrogen activation: a carbon-hydrogen-iridium bridge in [IrH2(mq)L2]BF4 and a CH + M .fwdarw. CMH reaction trajectory

Elizabeth M. Holt

Papers

Solution and solid-state molecular structures of Me2Sn(OAc)2 and its hydrolyzate, ([Me2Sn(OAc)]2O)2, by solution and solid-state carbon-13 NMR. X-ray diffraction study of the hydrolyzate

A randomised trial comparing endometrial resection and abdominal hysterectomy for the treatment of menorrhagia.

Inter- vs. intramolecular C-H activation: a C-H-Ir bridge in [IrH2(8-methylquinoline)L2]BF4 and a C-H+M→C-M-H reaction trajectory

Activation of coordinated carbon monoxide toward alkyl and aryl migration (carbon monoxide insertion) by molecular Lewis acids and x-ray structure of the reactive intermediate

Inter- vs. intramolecular carbon-hydrogen activation: a carbon-hydrogen-iridium bridge in [IrH2(mq)L2]BF4 and a CH + M .fwdarw. CMH reaction trajectory