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A field experiment was conducted with 24 indica-japonica hybrid rice varieties (lines) of Yongyou series, from which three types (high yield and high AE (agronomic nitrogen use efficiency) [HH], high yield and medium AE [HM], medium yield and medium AE [MM]) were selected to explore the characteristics of varieties with high yield and high AE. The yield of HH type was 4.04%–4.38% and 13.37%–13.41% higher than that of HM type and MM type respectively, owing to the larger number of total spikelets, which was 5.87×108–6.20×108 hm–2. Compared with HM and MM type, HH type had a high percentage of tiller rate, which was 68.83%–70.05%. The LAI of HH type was maximum at heading stage and declined slowly after heading. As a result, the LAI of HH type was above 3.85 at maturity stage. The dry matter accumulation of HH type was 7.91–7.99 t hm–2 from heading to maturity, which was the highest in three types, and its dry matter accumulation was more than 21.15–21.46 t hm–2 in the whole growth period. The total nitrogen uptake of HH type showed 5.07%–5.14% and 4.50%–5.96% increase than that of HM type and MM type respectively at maturity stage. The nitrogen sbsorption rate from jointing to heading stage and from heading to maturity stage showed HH type > HM type > MM type, as well as NTSH (N transportation from stem after heading), NIPH (N increase in panicle after heading) and NHI (N harvest index). HH type had the highest NRE (nitrogen recovery use efficiency), AE, PE (physiological nitrogen use efficiency) and PFP (partial factor productivity of applied N). Expect for NRE and NRG (nitrogen requirement for 100 kg grain), all the other nitrogen utilization indexes of HM type were higher than that of MM type.

Efficient use of tin-based composites plays an active role in energy-storage systems due to their high theoretical capacity and environmental benignity. But, large volume expansion during Li-ion insertion/extraction and undesirable aggregation of tin particles greatly limit the commercial application of Sn-based anodes. In this work, the SnO2 nanoparticles encapsulated in high-conductivity graphited carbon nanotubes (gCNTs) had been designed and synthesized by a facile wet chemical method, in which SnO2 nanoparticles with a diameter of 3–6 nm were protected by gCNT nano-containers. With the increase of graphiting temperature from 2400°C to 2800°C, more SnO2 nanoparticles were encapsulated in the gCNT containers instead of being attached to the outer surface. The SnO2/gCNT composites showed an excellent Li-ion storage capability and long cycling stability. The initial discharge capacities of the SnO2-gCNT composites were 1455 mAh g−1, and kept final capacity of 383 mAh g−1 after 620 cycles at 4 A g−1. Furthermore, this work provides a simple and effective strategy to prepare the ultrafine nanoparticles encapsulated in high-conductivity gCNTs for Li-ion batteries.

Background Nitrogen management of crops, especially when mid-stage nitrogen is applied, is a key factor affecting the yield and grain quality of rice (Oryza sativa). Here, the timing of mid-stage nitrogen application was evaluated for its effect on rice grain quality by assessing the morphological structure and physicochemical properties of starch from two japonica rice cultivars growing in fields (Nangeng 9108 and Nangeng 5055). Results The experiment was arranged in a split-plot design, with the two rice cultivars as the main plot factor and three timings of mid-stage nitrogen application as the within-plot factor. Briefly, three applications were made: at the emergence of the top-sixth-leaf (ahead), the top-fourth-leaf (normal), and the top-second-leaf (delayed) of the main stem. Delaying mid-stage nitrogen application caused the starch granule surface to become uneven and significantly reduced its particle size, whereas it increased the polished rice rate, chalkiness degree, and protein content. Furthermore, the apparent amylose content decreased with a delay in mid-stage nitrogen application, thereby resulting in higher relative crystallinity, swelling power, water solubility, gelatinization enthalpy, and low retrogradation. Finally, we also found that delaying this nitrogen application lowered the characteristic values of rice flour viscosities, leading to cooking quality deterioration. Conclusion These results therefore suggest that delaying mid-stage nitrogen application enhances the processing and nutritional qualities of japonica rice but evidently has an adverse effect upon its appearance and cooking qualities. © 2020 Society of Chemical Industry.

There is limited information about the combined effect of shading time and nitrogen (N) on grain filling and quality of rice. Therefore, two japonica super rice cultivars, Nanjing 44 and Ningjing 3, were used to study the effect of shading time and N level on the characteristics of rice panicle and grain filling as well as the corresponding yield and quality. At a low N level (150 kg N ha−1, 150N), grain yield decreased (by 21.07–26.07%) under the treatment of 20 days of shading before heading (BH) compared with the no shading (NS) treatment. These decreases occurred because of shortened panicle length, decreased number of primary and secondary branches, as well as the grain number and weight per panicle. At 150N, in the treatment of 20 days of shading after heading (AH), grain yield also decreased (by 9.46–10.60%) due to the lower grain weight per panicle. The interaction of shading and N level had a significant effect on the number of primary and secondary branches. A high level of N (300 kg N ha−1, 300N) could offset the negative effect of shading on the number of secondary branches and grain weight per panicle, and consequently increased the grain yield in both shading treatments. In superior grains, compared with 150N NS, the time to reach 99% of the grain weight (T99) was shortened by 1.6 to 1.7 days, and the grain weight was decreased by 4.18–5.91% in 150N BH. In 150N AH, the grain weight was 13.39–13.92% lower than that in 150N NS due to the slow mean and the maximum grain-filling rate (GRmean and GRmax). In inferior grains, grain weight and GRmean had a tendency of 150N NS>150N BH>150N AH. Under shaded conditions, 300N decreased the grain weight due to lower GRmean both in superior and inferior grains. Compared with 150N NS, the milling and appearance qualities as well as eating and cooking quality were all decreased in 150N BH and 150N AH. Shading with the high level of 300N improved the milling quality and decreased the number of chalky rice kernels, but the eating and cooking quality was reduced with increased chalky area and overall chalkiness. Therefore, in the case of short term shading, appropriate N fertilizer could be used to improve the yield and milling quality of rice, but limited application of N fertilizer is recommended to achieve good eating and cooking quality of rice.

Two cobalt(II) metal–organic frameworks with 2-fold vertically interpenetrated (4,4) grids, namely, [Co(bpg)2(SCN)2]·3MeOH (1) and [Co(bpg)2(SCN)2]·2DMF (2) (bpg = meso-α,β-bi(4-pyridyl) glycol), w...

Density functional theory (DFT) calculations have been employed to investigate hydrosilylation of carbonyl compounds catalyzed by three high-valent molybdenum (VI) hydrides: Mo(NAr)H(Cp)(PMe3) (1A), Mo(NAr)H(PMe3)3 (1B), and Mo(NAr)H (Tp)(PMe3) (Tp = tris(pyrazolyl) borate) (1C). Three independent mechanisms have been explored. The first mechanism is “carbonyl insertion pathway”, in which the carbonyls insert into Mo−H bond to give a metal alkoxide complex. The second mechanism is the “ionic hydrosilylation pathway”, in which the carbonyls nucleophilically attacks η1-silane molybdenum adduct. The third mechanism is [2 + 2] addition mechanism which was proposed to be favorable for the high-valent di-oxo molybdenum complex MoO2Cl2 catalyzing the hydrosilylation. Our studies have identified the “carbonyl insertion pathway” to be the preferable pathway for three molybdenum hydrides catalyzing hydrosilylation of carbonyls. For Mo(NAr)H (Tp)(PMe3) (Tp = tris(pyrazolyl) borate), the proposed nonhydride mechanism experimentally is calculated to be more than 32.6 kcal/mol higher than the “carbonyl insertion pathway”. Our calculation results have derived meaningful mechanistic insights for the high-valent transition metal complexes catalyzing the reduction reaction.

Although previous researchers have revealed that inter-sub-specific hybrid rice between indica and japonica has super-high yield potential, the mechanisms underlying nutrient absorption and utilization remain limited. The present study assessed nutrient accumulation and utilization, root morphology, and physiology of inter-sub-specific hybrid super rice cultivars (IHSRC) Yongyou 12 and Yongyou 15, using inbred japonica super rice cultivars (IJSRC) Nanjing 44 and Ningjing 3 as control. Total nitrogen (N), phosphorus (P), and potassium (K) accumulations in IHSRC were 12.53%, 20.81%, and 17.30% higher than those in IJSRC respectively. The larger amounts of accumulated nutrients in IHSRC were mainly attributable to the high rates of nutrients accumulation before elongating and the long growth duration without premature senescence after elongating. The apparent recovery efficiency of N fertilizers, agronomic N use efficiency, and the partial factor productivity of applied N in IHSRC were all higher than those in IJSRC, whereas the physiological N use efficiency and internal N, P, and K use efficiencies of IHSRC were similar to or lower than those of IJSRC. Compared with IJSRC, the root weights of IHSRC were heavier with greater length and bigger volume, the total and active absorption areas were also larger. In conclusion, with strong and active root systems, IHSRC are more efficient in nutrient absorption than utilization.

The first triradical bridged binuclear penta-spin single-molecule magnet, [Dy2(hfac)6(BTR)], based on a nitronyl nitroxide triradical was synthesized and characterized. Theoretical calculations revealed Dy-radical antiferromagnetic coupling and radical-radical ferromagnetic coupling. The SMM behavior is found to originate from the exchange states, rather than the isolated Dy3+ center.

Although studies on the balance between yield and quality of japonica soft super rice are limited, they are crucial for super rice cultivation. In order to investigate the effects of nitrogen application rate on grain yield and rice quality, two japonica soft super rice varieties, Nanjing 9108 (NJ 9108) and Nanjing 5055 (NJ 5055), were used under seven N levels with the application rates of 0, 150, 187.5, 225, 262.5, 300, and 337.5 kg ha −1 . With the increasing nitrogen application level, grain yield of both varieties first increased and then decreased. The highest yield was obtained at 300 kg ha −1 . The milling quality and protein content increased, while the appearance quality, amylose content, gel consistency, cooking/eating quality, and rice flour viscosity decreased. Milling was significantly negatively related with the eating/cooking quality whereas the appearance was significantly positively related with cooking/eating quality. These results suggest that nitrogen level significantly affects the yield and rice quality of japonica soft super rice. We conclude that the suitable nitrogen application rate for japonica soft super rice, NJ 9108 and NJ 5055, is 270 kg ha −1 , under which they obtain high yield as well as superior eating/cooking quality.

The well-controlled structural motifs of zirconium metal-organic frameworks (Zr-MOFs) and their similarity to enzyme cofactors make them ideally suited for biomimetic catalysis. However, the activation methodologies for these motifs, the structural information about active conformations and the reaction mechanism during these biomimetic reactions, are largely unknown. Herein, we have explored the precise pH-controlled activation processes, active sites, and reaction mechanisms for a series of Zr-MOFs as alkaline phosphatase mimics. Activation of the Zr-MOFs with a broad range and precise changes of pH led to the discovery of the MOF-catalyzed volcano plot with activity versus pH changes. This unique response revealed the existence of the precisely pH-controlled active form of the material, which was confirmed with computational analysis using density functional theory and diffuse reflectance infrared Fourier transform spectroscopy. These results will open a window for state-of-the-art design of efficient MOF enzyme mimics in aqueous solution.

Nitrogen management (nitrogen application ratio at transplanting, tillering, and panicle initiation growth stages) is an important parameter in crop cultivation and is closely associated with rice yield and grain quality. The physicochemical and structural properties of starches separated from two rice varieties grown under three different nitrogen management ratios (9:1; 7:3; 6:4) were investigated. As the percentage of nitrogen used in the panicle initiation stage increased, the content of small starch granules improved, whereas the content of large granules decreased. Amylose content decreased with increasing nitrogen ratio at the panicle initiation stage, thereby resulting in high swelling power, water solubility, gelatinization enthalpy, and low retrogradation. The X-ray diffraction patterns of the starches were found to be A type. The present study indicated that the best nitrogen management ratio for the cultivation of rice with the highest yield, desirable starch physicochemical properties for high quality cooked rice, and a moderate protein level is 7:3.

The catalytic hydrosilylation of carbonyl compounds by the high-valent mono-oxo rhenium(V) complex Re(O)Cl 3 (PPh 3 ) 2 ( 1 ) was theoretically investigated to determine the underlying reaction mechanism. According to our results, an ionic mechanistic pathway featuring an S N 2–Si structure of the transition state is the most favored. The ionic mechanistic catalytic cycle is initiated by the nucleophilic attack of the η 1 –silane metal adduct by carbonyl substrates. This attack results in the heterolytic cleavage of the Si H bond and generation of a silycarbenium ion paired with an anionic rhenium hydride, [Re(O)Cl 3 (H)(PPh 3 ) − [R 3 SiOCR′R″] + . Then by transferring the hydride from the metal center to the silycarbenium ion yields the silyl ether product. The activation energy of the turnover-limiting step was calculated as ∼24.1 kcal/mol with diphenylketone. This value is energetically more favorable than the σ-bond metathesis pathway that involves the initial exchange of silane hydrogen to chloride ligand generating the hydride intermediate, Re(O)HCl 2 (PPh 3 ) 2 by 7.4 kcal/mol. Furthermore, the [2 + 2] addition pathway involving the Si H bond that adds across Re O bond requires an activation energy that is ∼11.1 kcal/mol higher than that of the ionic mechanistic pathway. The strikingly different behavior of the mono-oxo-rhenium(V) complex and di-oxo-rhenium(V) complex – that favors a [2 + 2] addition mechanism – to activate the Si H bond of silanes is attributed to the absence of an oxo ligand in the mono-oxo-rhenium(V) complex. This decreases the electron density on the rhenium atom, enhances its electrophilicity, thus makes it favorable to prompt the heterolytic cleavage of the Si H bond upon the nucleophilic attack of carbonyl compounds.

The high-valent oxorhenium(V) complex [Re(O)(hoz)2]+ (1)-catalyzed hydrolytic oxidation of silanes to produce dihydrogen was studied computationally to determine the underlying mechanism. Our results suggested that the oxorhenium(V) complex 1-catalyzed hydrolysis/alcoholysis of silanes proceeds via the ionic out-sphere mechanistic pathway. The turnover-limiting step was found to be the heterolytic cleavage of the Si–H bond and featured a SN2–Si transition state, which corresponds to the nucleophilic anti attack of water or alcohol on the silicon atom in a cis η1-silane rhenium(V) adduct. Dihydrogen was generated upon transferring the hydride from the neutral rhenium hydride [Re(O)(hoz)2H] to the solvated [Me3SiOHR]+ ion. The activation free energy of the turnover-limiting step along the ionic outer-sphere pathway was calculated to be 15.7 kcal mol−1 with water, 15.4 kcal mol−1 with methanol, and 15.9 kcal mol−1 with ethanol. These values are energetically more favorable than the [2 + 2] addition pathway by ~15.0 kcal mol−1. Furthermore, the previously proposed catalytic pathways involving transient rhenium(VII) complexes or via the silicon attack on a rhenium hydroxo/alkoxo complex are shown to possess higher barriers.

Density functional theory calculations with the B3LYP-D function have been performed to investigate the mechanism of carbonyl hydrosilylation reactions catalyzed by the high-valent nitridoruthenium(VI) complex [RuN(saldach)(CH3OH)]+[ClO4]− (1; saldach is the dianion of racemic N,N′-cyclohexanediylbis(salicylideneimine)). Our computational results indicate a favored ionic outer-sphere mechanistic pathway. This pathway initiates with a silane addition to the RuVI center, which proceeds through a SN2-Si transition state corresponding to the nucleophilic attack of the carbonyl on the silicon center. This attack then prompts the heterolytic cleavage of Si–H bond. The rate-determining energy of the SN2-Si transition state is calculated to be 22.9 kcal/mol with benzaldehyde. In contrast, our calculations indicate that the initial silane addition to the nitrido ligand does not represent an intermediate of the catalytic process leading to the silyl ether products, since it involves high-energy transition states (2...

It has long been observed that rare earth elements (REEs) regulate multiple facets of plant growth and development. However, the underlying mechanisms remain largely unclear. Here, using electron microscopic autoradiography, we show the life cycle of a light REE (lanthanum) and a heavy REE (terbium) in horseradish leaf cells. Our data indicate that REEs were first anchored on the plasma membrane in the form of nanoscale particles, and then entered the cells by endocytosis. Consistently, REEs activated endocytosis in plant cells, which may be the cellular basis of REE actions in plants. Moreover, we discovered that a portion of REEs was successively released into the cytoplasm, self-assembled to form nanoscale clusters, and finally deposited in horseradish leaf cells. Taken together, our data reveal the life cycle of REEs and their cellular behaviors in plant cells, which shed light on the cellular mechanisms of REE actions in living organisms.

In the Jiangsu province of Southeast China, high irrigated rice yields are supported by high nitrogen (N) fertilizer inputs and low fertilizer N use efficiencies. A little attention has already been paid to the combined increase of rice yield and N use efficiency, however, the accumulation and utilization of N, phosphorus (P) and potassium (K) of irrigated rice genotypes with high yield and N use efficiency is still obscure. Field experiments were conducted in 2010 and 2011 where two cultivars with low productivity and low N use efficiency (LPLNE), two cultivars with high productivity and medium N use efficiency (HPMNE) and two cultivars with high productivity and high N use efficiency (HPHNE) were grown separately under their respective optimum N application to achieve maximum attainable yields. Accumulation and utilization of N, P and K as well as their interacting relationships were studied. The results showed that: (i) When values were averaged across cultivars and years, compared with LPLNE, HPMNE and HPHME showed 18.1, 25.3, and 9.6% higher N, P, K accumulations at maturity, respectively. The N grain production efficiency (NGPE) and K grain production efficiency (KGPE) were both higher, although P grain production efficiency (PGPE) showed no consistent tendencies; (ii) When values were averaged across cultivars and years, in comparison with HPMNE, HPHNE achieved a 1.7% lower total N accumulation, but a 6.5% higher N accumulation during the period from heading to maturity. At maturity, N accumulation in leaves increased by 3.5% and that in grains decreased by 4.0%. Total P and total K accumulation increased by 2.5% and 2.8%, respectively, which was mainly attributed to greater accumulation after panicle initiation, especially in the period from heading to maturity. At maturity, P accumulation in leaves increased by 11.5% and that in stems and grains did not differ significantly, K accumulation in stems increased by 4.2% and that in leaves and grains did not differ significantly. The N, P and K accumulation in grains at maturity did not explain the higher N use efficiency of HPHNE. This study suggested that a decrease of N accumulation before panicle initiation and increase of N, P, K accumulation during the period from heading to maturity may be helpful to combine the high yield and high N use efficiency in rice.

Recently, a series of oxo/nitrido-Re(V)/Mo(VI)/Ru(VI)/Mn(V) complexes were demonstrated to be efficient catalysts in activating silanes and catalyzing hydrosilylations of unsaturated organic substrates. In the present study, the high-valent molybdenum(VI)-dioxo complex MoO2Cl2 catalyzed hydrosilylations of carbonyls was reinvestigated using density functional theory method. Previous experimental and theoretical investigations suggested a [2 + 2] addition pathway for MoO2Cl2 catalyzed hydrosilylations of ketones. In the present study, we propose an ionic outer-sphere mechanistic pathway to be the most favorable pathway. The key step in the ionic outer-sphere pathway is oxygen atom of C═O bonds nucleophilically attacking the silicon atom in an η(1)-silane molybdenum adduct. The Si-H bond is then cleaved heterolytically. This process features a novel SN2@Si transition state, which then generates a loosely bound ion pair: anionic molybdenum hydride paired with silylcarbenium ion ([MoO2Cl2H](-) [SiR3(OCR'R″)](+)) in solvent. The last step is silylcarbenium ion abstracting the hydride on molybdenum hydride to yield silyl ether. The calculated activation free energy barrier of the rate-determing step was 24.1 kcal/mol for diphenylketone (PhC═OPh) and silane of PhMe2SiH. Furthermore, the ionic outer-sphere pathway is calculated to be ∼10.0 kcal/mol lower than the previously proposed [2 + 2] addition pathway for a variety of silanes and aldehyde/ketone substrates. This preference arises from stronger electrophilicity of the high-valent molybdenum(VI) metal center toward a hydride. Here, we emphasize MoO2Cl2 behaves similar to Lewis acidic trispentafluorophenyl borane B(C6F5)3 in activating Si-H bond.

We conducted field trials of rice grown in sandy soil and clay soil to determine the effects of nitrogen application levels on the concentration of NH4+-N in surface water, loss of ammonia through volatilization from paddy fields, rice production, nitrogen-use efficiency, and nitrogen content in the soil profile. The concentration of NH4+-N in surface water and the amount of ammonia lost through volatilization increased with increasing nitrogen application level, and peaked at 1-3 d after nitrogen application. Less ammonia was lost via volatilization from clay soil than from sandy soil. The amounts of ammonia lost via volatilization after nitrogen application differed depending on the stage when it was applied, from the highest loss to the lowest: N application to promote tillering > the first N topdressing to promote panicle initiation (applied at the last 4-leaf stage) > basal fertilizer > the second N topdressing to promote panicle initiation (applied at the last 2-leaf stage). The total loss of ammonia via volatilization from clay soil was 10.49-87.06 kg/hm2, equivalent to 10.92%-21.76% of the nitrogen applied. The total loss of ammonia via volatilization from sandy soil was 11.32-102.43 kg/hm2, equivalent to 11.32%-25.61% of the nitrogen applied. The amount of ammonia lost via volatilization and the concentration of NH4+-N in surface water peaked simultaneously after nitrogen application; both showed maxima at the tillering stage with the ratio between them ranging from 23.76% to 33.65%. With the increase in nitrogen application level, rice production and nitrogen accumulation in plants increased, but nitrogen-use efficiency decreased. Rice production and nitrogen accumulation in plants were slightly higher in clay soil than in sandy soil. In the soil, the nitrogen content was the lowest at a depth of 40-50 cm. In any specific soil layer, the soil nitrogen content increased with increasing nitrogen application level, and the soil nitrogen content was higher in clay soil than in sandy soil. In terms of ammonia volatilization, the amount of ammonia lost via volatilization increased markedly when the nitrogen application level exceeded 250 kg/hm2 in the rice growing season. However, for rice production, a suitable nitrogen application level is approximately 300 kg/hm2. Therefore, taking the needs for high crop yields and environmental protection into account, the appropriate nitrogen application level was 250-300 kg/hm2 in these conditions.

To investigate the effect of nitrogen (N) level on iron (Fe) content in milled rice, a field experiment was carried out under three N application levels including 0, 150 and 300 kg/hm2 by using 120 rice genotypes. In addition to the genotypic differences of iron content in milled rice, grain yield, 1000-grain weight and N content in grains under the same N level, there were also variations in the response of Fe content in milled rice to N levels. Based on the range and variation coefficient of Fe content in milled rice under the three N levels, the response of Fe content in milled rice to N levels could be classified into four types including highly insensitive, insensitive, sensitive and highly sensitive types. A significant quadratic correlation was found between the Fe content in milled rice and 1000-grain weight or the N content in grains. However, no significant correlation between the Fe content in milled rice and grain yield was detected. In conclusion, there are genotypic differences in the effects of N levels on Fe content in milled rice, which is favorable to breeding of Fe-rich rice under different N environments. Furthermore, high yield and Fe-rich rice could be grown through the regulation of nitrogen on Fe content in milled rice, 1000-grain weight and N content in milled rice.

To identify the photosynthetic mechanism of nitrogen (N) absorption and utilization in different rice (Oryza sativa L.) genotypes, relationships between photosynthetic characteristics of flag leaf and N use efficiency were investigated in 6 N-efficient and 6 N-inefficient rice genotypes with variable N use efficiency. The abilities of seed setting of the genotypes were also analyzed. The N application rate was 225 kg ha−1 for all genotypes. During grain filling, chlorophyll content, N content, net photosynthetic rate, photosynthetic function duration, maximum photochemical efficiency (Fv/Fm), potential photochemical efficiency of photosystem II (Fv/Fo), actual photochemical efficiency of photosystem II (ΦPSII), photochemical quenching coefficient (qP), and nonphotochemical quenching coefficient (qN) of flag leaf were obviously higher in the N-efficient genotypes than those in the N-inefficient genotypes. All these indexes were positively correlated with N use efficiency and seed-setting ability. Compared with the N-inefficient genotypes, the N-efficient genotypes had more favorable characteristics of photosynthesis and longer photosynthetic function duration. Besides, their PSII was steady for the large potential of converting light energy into electrochemical energy, and nonphotochemical quenching could also protect the photosynthetic apparatus. The accumulation of photosynthate and the seed-setting ability were enhanced in the N-efficient genotypes compared to the N-inefficient genotypes. Simultaneously, the N absorption and utilization of N efficient genotypes were improved through feedback regulation of roots and shoots.

The hydrosilylation of unsaturated carbon-heteroatom (C═O, C═N) bonds catalyzed by high-valent rhenium(V)-dioxo complex ReO2I(PPh3)2 (1) were studied computationally to determine the underlying mechanism. Our calculations revealed that the ionic outer-sphere pathway in which the organic substrate attacks the Si center in an η(1)-silane rhenium adduct to prompt the heterolytic cleavage of the Si-H bond is the most energetically favorable process for rhenium(V)-dioxo complex 1 catalyzed hydrosilylation of imines. The activation energy of the turnover-limiting step was calculated to be 22.8 kcal/mol with phenylmethanimine. This value is energetically more favorable than the [2 + 2] addition pathway by as much as 10.0 kcal/mol. Moreover, the ionic outer-sphere pathway competes with the [2 + 2] addition mechanism for rhenium(V)-dioxo complex 1 catalyzing the hydrosilylation of carbonyl compounds. Furthermore, the electron-donating group on the organic substrates would induce a better activity favoring the ionic outer-sphere mechanistic pathway. These findings highlight the unique features of high-valent transition-metal complexes as Lewis acids in activating the Si-H bond and catalyzing the reduction reactions.

We herein reported the syntheses, crystal structures, and magnetic properties of a two-dimensional coordination polymer {[CoII(TPT)2/3(H2O)4][CH3COO]2·(H2O)4}n (1) and a chain compound {[CoII(TPT)2(CHOO)2(H2O)2]}n (2) based on the 2,4,6-Tris(4-pyridyl)-1,3,5-triazine (TPT) ligand. Structure analyses showed that complex 1 had a cationic hexagonal framework structure, while 2 was a neutral zig-zag chain structure with different distorted octahedral coordination environments. Magnetic measurements revealed that both complexes exhibit large easy-plane magnetic anisotropy with the zero-field splitting parameter D = 47.7 and 62.1 cm−1 for 1 and 2, respectively. This magnetic anisotropy leads to the field-induced slow magnetic relaxation behaviour. However, their magnetic dynamics are quite different; while complex 1 experienced a dominating thermally activated Orbach relaxation at the whole measured temperature region, 2 exhibited multiple relaxation pathways involving direct, Raman, and quantum tunneling (QTM) processes at low temperatures and Orbach relaxation at high temperatures. The present complexes enlarge the family of framework-based single-ion magnets (SIMs) and highlight the significance of the structural dimensionality to the final magnetic properties.

In this study, we theoretically investigated the mechanism underlying the high-valent mono-oxo-rhenium(V) hydride Re(O)HCl2(PPh3)2 (1) catalyzed hydrosilylation of C=N functionalities. Our results suggest that an ionic S(N)2-Si outer-sphere pathway involving the heterolytic cleavage of the Si-H bond competes with the hydride pathway involving the C=N bond inserted into the Re-H bond for the rhenium hydride (1) catalyzed hydrosilylation of the less steric C=N functionalities (phenylmethanimine, PhCH=NH, and N-phenylbenzylideneimine, PhCH=NPh). The rate-determining free-energy barriers for the ionic outer-sphere pathway are calculated to be ∼28.1 and 27.6 kcal mol(-1), respectively. These values are slightly more favorable than those obtained for the hydride pathway (by ∼1-3 kcal mol(-1)), whereas for the large steric C=N functionality of N,1,1-tri(phenyl)methanimine (PhCPh=NPh), the ionic outer-sphere pathway (33.1 kcal mol(-1)) is more favorable than the hydride pathway by as much as 11.5 kcal mol(-1). Along the ionic outer-sphere pathway, neither the multiply bonded oxo ligand nor the inherent hydride moiety participate in the activation of the Si-H bond.

A series of end-to-end azido-bridged per- ovskite-type compounds ((CH3)nNH4−n)(Mn(N3)3 )( n = 1−4) were synthesized and characterized. Structural phase transitions indicating the general lattice flexibility were observed and confirmed by the crystal structures of different phases. These materials show cation-dependent magnetic ordering at up to 92 K and magnetic bistability near room temperature.

In order to investigate proper potassium application rate and its effects on growth and grain yield for Yongyou japonica/indica hybrids series, a field experiment was conducted using Yongyou 12 and Yongyou 538 with five treatments of 0, 75, 150, 225, and 300 kg ha potassium application. Results indicated that compared with check treatment (0 kg ha), potassium

The difference of dry matter production and translocation characteristics in low-yielding and low N-efficiency, high-yielding and medium N-efficiency, high-yielding and high N-efficiency rice cultivars was investigated using six representative japonica varieties under their optimum N supply levels, respectively. The results indicated that: with the increase of rice productivity, the total dry matter production amount significantly increased by 20.29% on average, and the dry matter accumulation amount and population growth rate increased on average by 15.05%, 27.04%, 24.75% and 15.05%, 28.38%, 23.00%, during the period before N-n (critical stage of productive tillering), from jointing to heading, and from heading to maturing, respectively, and decreased during the period from N-n to the jointing. Among the high-yielding varieties, with the nitrogen use efficiency increased, the tiller number per unit area at each growth stage showed a downward trend, and significantly reduced on average by 5.76%, 11.61%, 7.01%, and 5.70% at N-n, jointing, heading and maturing, respectively, but ratio of productive tillers to total tillers significantly increased. At each growth stage, the dry matter accumulation amount showed a declined tendency, and reduced on average by 12.18%, 10.54%, 8.29%, and 5.01% at N-n, jointing, heading and maturity, respectively, but harvest indexsignificantly increased. During the period from heading to maturing, dry matter accumulation rate increased on average by 5.40%, the population growth rate increased on average by 5.19%. The results above showed that proper control for population growth before heading, maintaining a high growth rate after heading and a higher harvest index were the important dry matter accumulation characteristics of the cultivars with high-yielding and high nitrogen use efficiency.