Layered lanthanide phosphonates Ln(2-qpH)(SO4)(H2O)2 (Ln = La, Ce, Pr, Nd, Sm): polymorphism and magnetic properties.

Polymorphic layered lanthanide coordination polymers provide opportunities to study the effect of intralayer and interlayer interactions on their magnetic dynamics. Herein we report a series of layered lanthanide phosphonates, namely, α-Ln(2-qpH)(SO4)(H2O)2 (Ln = Sm) (α-Ln), ß-Ln(2-qpH)(SO4)(H2O)2 (Ln = Pr, Nd, Sm) (ß-Ln) and γ-Ln(2-qpH)(SO4)(H2O)2 (Ln = La, Ce, Pr, Nd, Sm) (γ-Ln) (2-qpH2 = 2-quinolinephosphonic acid), which crystallize in monoclinic P21/c (α-Ln), triclinic P1̄ (ß-Ln) and orthorhombic Pbca (γ-Ln) space groups, respectively. The structural differences between the ß- and γ-phases lie not only in the intralayer but also in the interlayer. Within the layers, the Ln2O2 dimers are aligned parallel in the ß-phase, but are non-parallel in the γ-phase. In the interlayer, there are π-π interactions between the quinoline groups in the α- and ß-phases but not in the γ-phase. Magnetic studies reveal a field-induced slow relaxation of the magnetisation at low temperatures for compounds γ-Ce, ß-Nd, and γ-Nd, and the impact of polymorphism on the magnetic dynamics of Nd(III) compounds is discussed.

Photo-responsive Single-Molecule Magnet Showing 0D to 1D Single-Crystal-to-Single-Crystal Structural Transition and Hysteresis Modulation.

Photo-responsive lanthanide-based single-molecule magnets (SMM) hold great promise for future switching and memory devices. Herein, we report a dysprosium phosphonate [DyIII (SCN)2 (NO3 )(depma)2 (4-hpy)2 ] (1Dy), which features a supramolecular framework containing layers of hydrogen-bonding network and pillars of π-π interacted anthracene units. The photocycloaddition reaction of anthracene pairs led to a rapid and reversible single-crystal-to-single-crystal (SC-SC) structural transition to form the 1D coordination polymer [DyIII (SCN)2 (NO3 )(depma2 )(4-hpy)2 ]n (2Dy), accompanied by photoswitchable SMM properties with the reduction of effective energy barrier by half and the narrowing of the butterfly-like hysteresis loop. The diluted sample showed a photo-induced switch of the blocking temperature (TB ) from 3.8 K for 1Dy@Y to 2.6 K for 2Dy@Y. This work may inspire the construction of lanthanide-based molecular materials with targeted photo-responsive magnetic properties.

Photocontrollable Magnetism and Photoluminescence in a Binuclear Dysprosium Anthracene Complex.

By incorporating photoreactive anthracene moieties into binuclear Dy2O2 motifs, we obtain two new compounds with the formulas [Dy2(SCN)4(L)2(dmpma)4] (1) and [Dy2(SCN)4(L)2(dmpma)2(CH3CN)2] (2), where HL is 4-methyl-2,6-dimethoxyphenol and dmpma is dimethylphosphonomethylanthracene. Compound 1 contains face-to-face π-π interacted anthracene groups that meet the Schmidt rule for a [4 + 4] photocycloaddition reaction, while stacking of the anthracene groups in compound 2 does not meet the Schmidt rule. Compound 1 undergoes a reversible single-crystal-to-single-crystal structural transformation upon UV-light irradiation and thermal annealing, forming a one-dimensional coordination polymer of [Dy2(SCN)4(L)2(dmpma)2(dmpma2)]n (1UV). The process is concomitant with changes in the magnetic dynamics and photoluminescent properties. The spin-reversal energy barrier is significantly increased from 1 (55.9 K) to 1UV (116 K), and the emission color is changed from bright yellow for 1 to weak blue for 1UV. This is the first binuclear lanthanide complex that exhibits synergistic photocontrollable magnetic dynamics and photoluminescence. Ab initio calculations are conducted to understand the magnetostructural relationships of compounds 1, 1UV, and 2.

Polymorphism modulates photoluminescence and magnetic dynamics of mononuclear dysprosium-anthracene complexes.

Complexes α-Dy(depma)3Cl3 (α-DyCl), ß-Dy(depma)3Cl3 (ß-DyCl) and ß-Dy(depma)3Br3 (ß-DyBr) (depma = 9-diethylphosphono-methylanthracene) are reported. α-DyCl and ß-DyCl are polymorphs showing distinct magnetic dynamics with energy barriers of 32.3 K and 66.6 K. They also show distinct luminescence properties with emission peaks at 487 nm and 530 nm, respectively.

Surface potential-determined performance of Ti3C2T2 (T = O, F, OH) and Zr3C2T2 (T = O, F, OH, S) MXenes as anode materials of sodium ion batteries.

Sodium ion batteries (SIBs) have attracted increasing attention due to their low cost and abundant reserves of sodium, but their ideal anode materials still need to be explored. MXenes could be candidate electrode materials due to their excellent electrical conductivity and large specific surface area. In this work, the theoretical performance of Ti- and Zr-containing MXenes Ti3C2T2 (T = O, F, OH) and Zr3C2T2 (T = O, F, OH, S) as SIB anode materials is investigated. The influence of the Hubbard U correction is discussed, and the behaviour at the MXene surface with the partial occupation of sodium atoms is considered. Including the weight and volume of adsorbed sodium atoms, Ti3C2O2 presents the best performance among the seven MXenes studied. Its mass and volumetric capacities are 299 mA h g-1 and 993 mA h cm-3 respectively, and the migration barrier and open circuit voltage are 0.138 eV and 0.421 V. Both Zr3C2O2 and Zr3C2S2 can adsorb double layers of sodium atoms on both sides, and the former shows a higher capacity because of its lower weight and smaller volume. The mass and volumetric capacities of Zr3C2O2 are 254 mA h g-1 and 913 mA h cm-3 respectively. More importantly, the surface potential is determined to be an effective descriptor for selecting electrode materials. The migration barrier is proportional to the fluctuation amplitude of the surface potential. A low surface potential generally implies a high capacity. A large open circuit voltage is prone to appear in the structure with a large fluctuation amplitude and a low average value of its surface potential.

Dual-sensitized Eu(III)/Tb(III) complexes exhibiting tunable luminescence emission and their application in cellular-imaging.

Two novel dual-photosensitized stable complexes, namely [Eu(dpq)(BTFA)3] (1) and [Tb(dpq)(BTFA)3] (2), have been successfully assembled via a mixed ligand approach using dipyrido[3,2-d:2',3'-f]quinoxaline (dpq) and 3-benzoyl-1,1,1-trifluoroacetone (BTFA). The crystallographic data reveal mononuclear lanthanide cores in both 1 and 2, in which each eight-coordinated Ln(III) ion is located in a slightly distorted dodecahedron (D2d). The room-temperature photoluminescence spectra of complexes 1 and 2 indicate that both BTFA and dpq can effectively sensitize Eu(III) and Tb(III) characteristic luminescence. Moreover, heterometallic Ln-complexes can be synthesized, leading to a new series of differently doped EuxTb1-x complexes. Luminescence experiments on them reveal dual-emission peaks of Eu3+ and Tb3+, which lead to a gradual change in the luminous colour between yellow-green, yellow, orange, orange-red and red upon increasing the Eu3+ content. On the basis of the intrinsic strong emission properties and nontoxic nature of complexes 1 and 2, we explore their potential application as cellular imaging agents. Fluorescence microscopy data suggest the cytosolic and nuclear localization of 1 and 2 in HeLa and MCF-7 cells.

Role of the A-Element in the Structural, Mechanical, and Electronic Properties of Ti3AC2 MAX Phases.

Combining metallic and ceramic properties, and as precursors for MXenes, MAX phases have attracted extensive attention. In recent years, A-element substitution has been demonstrated as an effective scheme to enrich the MAX family. To explore more possible MAX members, the structural, mechanical, and electronic properties and stabilities of 31 Ti3AC2 (A = Al, Si, P, S, Fe, Co, Ni, Cu, Zn, Ga, Ge, As, Se, Ru, Rh, Pd, Ag, Cd, In, Sn, Sb, Te, Os, Ir, Pt, Au, Hg, TI, Pb, Bi, and Po) configurations are investigated in this work. Moreover, the interfacial strength implicating the possibility of exfoliating MAX into MXenes is examined. The A-element plays a crucial role in the lattice parameters and mechanical strength of Ti3AC2, and their variations are well explained by the synergistic effects of d-d and p-d hybridizations between the valence orbitals of Ti and A. Ti3SC2 presents the largest Young's modulus of 360 GPa, which is 6.82% higher than that in the well-studied Ti3SiC2. Ti3SbC2 is a mechanical quasi-isotropic configuration. After checking the mechanical, dynamical, and thermodynamic stability, Ti3AC2 (A = Al, Si, P, S, Ga, Ge, As, Cd, In, Sn, Sb, Au, Hg, Pb, TI, and Po) are stable, while Ti3AC2 (A = Fe, Co, Zn, Se, Ru, Rh, Pd, Ag, Te, Ir, Pt, and Bi) are metastable. Compared to Ti3AlC2, Ti3AC2 (A = Ag, Sb, Te, Bi, and Po) exhibit much lower interfacial strength in Ti-A interfaces and larger ratios between the interfacial strengths of neighboring Ti-C and Ti-A interfaces. This implies that these configurations are promising precursors for the synthesis of Ti3C2Tx (Tx denotes surface groups) with a large flake size. All of the configurations are metallic, and Ti3AC2 (A = Fe and Co) are magnetic. Based on the phonon dispersion and electronic structure, these Ti3AC2 configurations might have potential applications in phononic crystals and topological materials.

Regulating the magnetic dynamics of mononuclear ß-diketone Dy(iii) single-molecule magnets through the substitution effect on capping N-donor coligands.

A series of five mononuclear ß-diketonate-Dy(iii) complexes, with formulas Dy(ntfa)3(Br-bpy) (1), Dy(ntfa)3(Br2-bpy) (2), Dy(ntfa)3(5,5-(CH3)2-bpy) (3), Dy(ntfa)3(4,4-((CH3)3)2-bpy) (4) and Dy(ntfa)3(4,4-(CH3)2-bpy) (5) (ntfa = 4,4,4-trifluoro-1-(2-naphthyl)-1,3-butanedione, Br-bpy = 5-bromo-2,2'-bipyridine, Br2-bpy = 4,4'-dibromo-2,2'-bipyridine, 5,5-(CH3)2-bpy = 5,5'-di-methyl-2,2'-bipyridine, 4,4-((CH3)3)2-bpy = 4,4'-di-tert-butyl-2,2'-bipyridine, and 4,4-(CH3)2-bpy = 4,4'-di-methyl-2,2'-bipyridine), have been prepared by altering the capping N-donor coligands. Dy(iii) ions in all complexes possess N2O6 octa-coordinated environments, displaying a distorted square antiprismatic D4d symmetry in complexes 1-4, as well as a triangular dodecahedron D2d symmetry in 5. Magnetic investigations evidence the SIM behavior in the five complexes with the energy barriers (Ueff) of 104.19 K (1), 122.93 K (2), 84.20 K (3), 64.16 K (4) and 80.23 K (5) under zero applied dc field. The potential QTM effects in the title complexes are successfully suppressed in the presence of the extra applied fields. The crystal field parameters and orientations of the magnetic easy axes were obtained from the simulation of the magnetic data and the electrostatic model calculation. The distinct electronic effects originating from the subtle changes of the substituents on the capping N-donor coligands induce varying coordination microenvironments and geometries on the Dy(iii) sites, further drastically impacting the overall magnetic properties of the title complexes. The disparities of the uniaxial anisotropy and the magnetic dynamics for 1-5 have been elucidated by ab initio calculations as well.

A series of lanthanide(III) metal-organic frameworks derived from a pyridyl-dicarboxylate ligand: single-molecule magnet behaviour and luminescence properties.

The reactions of LnIII ions with a versatile pyridyl-decorated dicarboxylic acid ligand lead to the formation of a series of novel three-dimensional (3D) Ln-MOFs, [Ln3(pta)4(Hpta)(H2O)]·xH2O (Ln = Dy (1), Eu (2), Gd (3), Tb (4), H2pta = 2-(4-pyridyl)-terephthalic acid, x = 6 for 1, 2.5 for 2, 1.5 for 3 and 2 for 4). The Ln3+ ions act as nine-coordinated muffin spheres, linking to each other to generate trinuclear {Ln3(OOC)6N2} SBUs, which are further extended to be interesting 3D topological architectures. To the best of our knowledge, the Dy-MOF exhibits zero-field single-molecule magnet (SMM) behaviour with the largest effective energy barrier among the previously reported 3D MOF-based Dy-SMMs. The combined analyses of a diluted sample (1@Y) and ab initio calculations demonstrate that the thermally assisted slow relaxation is mainly attributed to the single-ion magnetism. Furthermore, fluorescence measurements reveal that H2pta can sensitize EuIII and TbIII characteristic luminescence.

Modulating energetic performance through decorating nitrogen-rich ligands in high-energy MOFs.

In the presence of different nitrogen-rich ligands, two energetic MOFs with formulas [Ag(tza)]n (1) and [Ag(atza)]n (2) (Htza = tetrazole-1-acetic acid and Hatza = (5-amino-1H-tetrazole-1-yl) acetic acid) were successfully synthesized and characterized. X-ray single crystal structure analysis shows that both 1 and 2 have 2D layer-like topologies. The experimental and theoretical evaluations reveal the promising properties of both energetic compounds, such as prominent heats of detonation, high thermal stabilities, good sensitivities and excellent detonation performances. In contrast to 1, interestingly, the introduction of the amino group in 2 leads to various coordination modes of the ligands and different stacking patterns of the frameworks, resulting in the observation of the shorter Ag-O, Ag-Ag, C-N, N-N, and N[double bond, length as m-dash]N bond lengths in 2. Consequently, 2 features superior heats of detonation and thermostability compared to 1. The nonisothermal thermokinetic parameters are obtained by using the Kissinger and Ozawa methods, while the standard molar enthalpies of formation are calculated from the determination of constant volume combustion energies. In addition, both compounds were explored as practical additives to promote the thermal decomposition of ammonium perchlorate (AP). This work may provide an effective approach for manipulating the energetic properties and thermostability of high-energy compounds via the perturbation of energetic groups.

Trends in C-O and N-O bond scission on rutile oxides described using oxygen vacancy formation energies.

Reactivity trends on transition metals can generally be understood through the d-band model, but no analogous theory exists for transition metal oxides. This limits the generality of analyses in oxide-based catalysis and surface chemistry and has motivated the appearance of numerous descriptors. Here we show that oxygen vacancy formation energy (ΔE Vac) is an inexpensive yet accurate and general descriptor for trends in transition-state energies, which are usually difficult to assess. For rutile-type oxides (MO2 with M = 3d metals from Ti to Ni), we show that ΔE Vac captures the trends in C-O and N-O bond scission of CO2, CH3OH, N2O, and NH2OH at oxygen vacancies. The proportionality between ΔE Vac and transition-state energies is rationalized by analyzing the oxygen-metal bonds, which change from ionic to covalent from TiO2 to NiO2. ΔE Vac may be used to design oxide catalysts, in particular those where lattice oxygen and/or oxygen vacancies participate in the catalytic cycles.

Enhancing single-molecule magnet behaviour through decorating terminal ligands in Dy2 compounds.

The utilization of two isomorphic ligands with different substituents leads to two centrosymmetric DyIII dimers, namely, [Dy2(bfbpen)2(H2O)2]·2I- (1) and [Dy2(bcbpen)2(H2O)2]·2I-·0.5H2O (2) (H2bfbpen = N,N'-bis-(2-hydroxy-5-fluoro-benzyl)-N,N'-bis-(pyridin-2-ylmethyl)ethylenediamine and H2bcbpen = N,N'-bis-(2-hydroxy-5-chloro-benzyl)-N,N'-bis-(pyridin-2-ylmethyl)ethylenediamine). Although Dy ions in both compounds uniformly exhibit a square-antiprism geometry, the critical difference found in the terminal substituents of the two ligands fine-tunes the local crystal field around Dy centers and the dinuclear molecular structures of 1 and 2. Magnetic investigations unveil that both 1 and 2 display dynamic magnetic relaxation of single-molecule magnet (SMM) behaviour with different energy barriers of 20.9 K for 1 and 72.7 K for 2 under a zero direct-current (dc) field, as well as 26.9 K for 1 under a 1200 Oe dc field. Compared to 1, the stronger uniaxial anisotropy and magnetic exchange in 2 render it a better SMM as evidenced by the higher energy barrier. Ab initio calculations are also performed on both Dy2 compounds to rationalize the observed discrepancy in their magnetic behaviours. The contribution illustrates that the SMM behaviour could be effectively enhanced by means of deliberate local structural manipulation.

Solvent-induced single-crystal-to-single-crystal transformation and tunable magnetic properties of 1D azido-Cu(ii) chains with a carboxylate bridge.

By means of the solvent effect, three new azido-copper 1D coordination polymers, [Cu(4-aba)(N3)] (1), [Cu(4-aba)(N3)(CH3OH)] (2), and [Cu(4-aba)(N3)(C2H5OH)] (3) (4-aba = 4-azidobenzoic acid), were successfully prepared in the presence of Cu2+ ion, NaN3 and 4-azidobenzoic acid. Interestingly, 1 can be employed as a precursor and transformed to 2 and 3via the coordination of methanol or ethanol, respectively. Meanwhile, the identical products of 1, namely 1a and 1b, could be obtained from both 2 and 3 by a dealcoholized process. As a result, the geometric configurations of Cu(ii) ions vary from the tetracoordinated square-planar in 1 to the hexacoordinated octahedron in 2 or 3. Compound 1 displays a well-isolated 1D chain with dual-bridges of EO-azido and syn,syn-carboxylate, while isomorphic 2 and 3 are triple-bridged chain-like motifs containing EO-azido, syn,syn-carboxylate and µ2-alkanol. The structural transformations caused by the intervention of alkanol molecules modulate the intrachain Cu-Cu distances (3.570 for 1, 3.204 Å for 2 and 3.154 Å for 3) and Cu-N-Cu angles (127.3° for 1, 106.82° for 2 and 104.81° for 3). This modulation, however, further leads to different intrachain ferromagnetic interactions (J = 28.4 cm-1 for 1, 67.6 cm-1 for 2, 40.2 cm-1 for 3) that are qualitatively demonstrated by theoretical calculation. More importantly, the significant scenarios of magnetic ordering and slow magnetic relaxation, which are infrequent in most of the reported azido-copper cases, are only observed in 2 and 3, due to the distinct interchain networks among 1-3. In addition, heat-capacity measurements highlight the characteristics of long-range ferromagnetic ordering in 2 and 3.

From fluorene molecules to ultrathin carbon nanonets with an enhanced charge transfer capability for supercapacitors.

It is a big challenge to synthesize ultrathin carbon nanonets with an enhanced charge transfer capability for high-performance energy storage devices. Herein, ultrathin carbon nanonets (UCNs) were successfully synthesized for the first time from fluorene, a typical aromatic molecule, by a template strategy for supercapacitors. The formation mechanism of UCNs was determined using Density Functional Theory and Materials Studio, in which the fluorene-derived radicals were assembled into UCNs in the template-confinement space with the assistance of KOH. The as-made UCNs feature interconnected high-conductivity net-like architectures with enhanced charge transfer capability, evidenced by their high capacitance, excellent rate performance and cycling stability for symmetrical supercapacitors in a KOH electrolyte. This finding may provide a significant step forward in understanding the formation mechanism of graphene-like materials from more complicated aromatic hydrocarbon molecules, and our work may draw wide attention in the fields of aromatic chemistry and carbon-based energy storage materials.

Concise Chemistry Modulation of the SMM Behavior within a Family of Mononuclear Dy(III) Complexes.

By means of the facile chemistry, structural assembly, and transformation of four mononuclear Dy(III) complexes, Dy(bpad)3·CH3OH·H2O (1), Dy(bpad)2(H2O)2·NO3 (2), [Dy(bpad)2(tmhd)] (3), and [Dy(bpad)2(btfa)] (4) (Hbpad = N3-benzoylpyridine-2-carboxamidrazone, tmhd = 2,2,6,6-tetramethylheptane-3,5-dione, btfa = 3-benzoyl-1,1,1-trifluoroacetone), with distinct architectures and local symmetries were established. The disparity of the coordination geometries around the Dy(III) ion among these complexes impacts the strength of the crystal field and the local tensor of anisotropy ( D) of each Dy site and their relative orientations, therefore giving rise to diverse SIM behaviors with distinguishing relaxation energy barriers of 106.93 K for 1, 52.55 K for 2, 48.16 K for 3, and 51.41 K for 4. The differences of the magnetic property and the magnetic anisotropy for four complexes have been explained by ab initio calculations, which are corresponding to the experimental results.

Otoprotective effects of ethosuximide in NOD/LtJ mice with age-related hearing loss.

Despite long-term efforts to elucidate the mechanisms responsible for age-related hearing loss (AHL), there is currently no available treatment strategy able to provide a cure. Apoptotic cell death, including that of hair cells and spiral ganglion neurons (SGNs) in the cochlea has been proposed to be the classic theory behind the development of AHL. As calcium signaling plays key roles in signal transduction in apoptosis, in this study, we selected ethosuximide, which is able to block T-type calcium (Ca2+ion) channels, suppressing Ca2+. We hypothesized that the apoptotic pathway may be blocked through the inhibition of T-type Ca2+ channels in cochlear cells in NOD/LtJ mice. NOD/LtJ mice were divided into 2 groups as follows: the ethosuximide-treated and untreated (control) groups. Ethosuximide was administered by intraperitoneal injection every other day from post-natal day seven (P7) until the mice were 8 weeks of age. Following treatment, auditory-evoked brainstem response (ABR) thresholds and distortion product oto-acoustic emission (DPOAE) of the mice in the 2 groups were measured at different time points. Morphometric analysis and the expression of genes involved in the T-type Ca2+-mediated apoptotic pathway were monitored. The ABR and DPOAE results revealed that the NOD/LtJ mice exhibited early-onset and rapidly progressive AHL. A histological examination revealed that hair cell degeneration coincided with the progression of hearing loss. Hair cell and SGN was were significantly lower and auditory function was significantly improved in the ethosuximide-treated group compared to the untreated group. Our data thus indicate that ethosuximide prevents the degeneration of cochlear cells by regulating the expression of genes in apoptotic pathways. Our findings suggest that activating the T-type Ca2+ channel and downstream genes may be key pathological mechanisms responsible for AHL in NOD/LtJ mice.

Hearing Improvement in A/J Mice via the Mouse Nerve Growth Factor.

OBJECTIVES: To investigate the otoprotective effects of mouse nerve growth factor (mNGF) in A/J mice. METHODS: The mice at postnatal day 7 (P7) were randomly separated into a mNGF treated group (mNGF group) and a distilled water (for injection) treated group (control group). The mNGF dissolved in distilled water or distilled water alone was given to the mice once every other day from P7 by intramuscular injection in the hips. The otoprotective effects of mNGF in A/J mice were observed in a time course manner. The thresholds of auditory-evoked brainstem response (ABR) were tested from the age of the 3rd to the 8th week. Sections of the inner ears were stained by hematoxylin and eosin, and spiral ganglion neurons (SGNs) were observed at the age of the 3rd, the 6th,and the 8th week. Counts of whole mount outer hair cells (OHCs) in the cochleae were made at the age of 8 weeks. Expression of apoptosis related genes was determined by quantitative real-time polymerase chain reaction and Western blotting. RESULTS: ABR thresholds of the mNGF group were significantly lower than those of the control group at the age of the 6th and the 8th week. Moreover, the mNGF preserved OHC and SGN in the mouse cochleae in this period. Further experiments showed that the expression of caspase genes (including caspase-3) was inhibited in the mouse inner ears in the mNGF group. CONCLUSION: The mNGF improves hearing in A/J mice by preserving SGN and OHC in the cochleae.

Harnessing the hidden genetic diversity for improving multiple abiotic stress tolerance in rice (Oryza sativa L.).

To develop superior rice varieties with improved yield in most rainfed areas of Asia/Africa, we started an introgression-breeding program for simultaneously improving yield and tolerances of multiple abiotic stresses. Using eight BC1 populations derived from a widely adaptable recipient and eight donors plus three rounds of phenotypic selection, we developed 496 introgression lines (ILs) with significantly higher yield under drought, salt and/or non-stress conditions in 5 years. Six new varieties were released in the Philippines and Pakistan and many more are being evaluated in multi-location yield trials for releasing in several countries. Marker-facilitated genetic characterization revealed three interesting aspects of the breeding procedure: (1) the donor introgression pattern in specific BC populations was characteristic; (2) introgression frequency in different genomic regions varied considerably, resulting primarily from strong selection for the target traits; and (3) significantly lower heterozygosity was observed in BC progenies selected for drought and salinity tolerance. Applying strong phenotypic selection under abiotic stresses in early segregating generations has major advantages for not only improving multiple abiotic stress tolerance but also achieving quicker homozygosity in early generations. This breeding procedure can be easily adopted by small breeding programs in developing countries to develop high-yielding varieties tolerant of abiotic stresses. The large set of trait-specific ILs can be used for genetic mapping of genes/QTL that affect target and non-target traits and for efficient varietal development by designed QTL pyramiding and genomics-based recurrent selection in our Green Super Rice breeding technology.

A new copper species based on an azo-compound utilized as a homogeneous catalyst for water oxidation.

A new azo-complex [(L)Cu(II)(NO3)] [L = (E)-3-(pyridin-2-yldiazenyl)naphthalen-2-ol (HL)], was prepared via a one-pot synthetic method at 60 °C and was structurally characterized by IR, EA, PXRD and single crystal X-ray diffraction. In addition, TGA studies indicated that the complex was stable in air. The redox properties were determined by cyclic voltammetry, which revealed that the complex could be utilized as a catalyst for water oxidation under mild conditions. Subsequently, the complex was employed as a catalyst to take part in water oxidation reaction in the presence of a Ce(IV) salt utilized as an oxidant at pH 11 in PBS (Phosphate Buffered Saline) solution. The results suggested that the catalyst exhibited a high stability and activity toward water oxidation reaction under these conditions with an initial TOF of 4.0 kPa h(-1). Calculation methodology was performed to study the mechanism of the reaction, which revealed that in this catalytic process, the initial oxidation of Cu(II) to Cu(III) occurred by the formation of an intermediate "Cu(III)-O-O-Cu(III)". The formation of this intermediate, resulted in a release of oxygen and closing of the catalytic cycle.

Genome-wide response to selection and genetic basis of cold tolerance in rice (Oryza sativa L.).

BACKGROUND: Cold stress is an important factor limiting rice yield in many areas of high latitude and altitude. Considerable efforts have been taken to genetically dissect cold tolerance (CT) in rice using DNA markers. Because of possible epistasis and gene × environment interactions associated with identified quantitative trait loci, the results of these genetic studies have unfortunately not been directly applicable to marker-assisted selection for improved rice CT. In this study, we demonstrated the utility of a selective introgression strategy for simultaneous improvement and genetic dissection of rice seedling CT. RESULTS: A set of japonica introgression lines (ILs) with significantly improved seedling CT were developed from four backcross populations based on two rounds of selection. Genetic characterization of these cold-tolerant ILs revealed two important aspects of genome-wide responses to strong phenotypic selection for rice CT: (1) significant over-introgression of donor alleles at 57 loci in 29 functional genetic units (FGUs) across the rice genome and (2) pronounced non-random associations between or among alleles at many unlinked CT loci. Linkage disequilibrium analyses of the detected CT loci allowed us to construct putative genetic networks (multi-locus structures) underlying the seedling CT of rice. Each network consisted of a single FGU, with high introgression as the putative regulator plus two to three groups of highly associated downstream FGUs. A bioinformatics search of rice genomic regions harboring these putative regulators identified a small set of candidate regulatory genes that are known to be involved in plant stress response. CONCLUSIONS: Our results suggest that CT in rice is controlled by multiple pathways. Genetic complementarity between parental-derived functional alleles at many loci within a given pathway provides an appropriate explanation for the commonly observed hidden diversity and transgressive segregation of CT and other complex traits in rice.