Search

Silicon flake powder (Si LeafPowder®, Si-LP) with the thickness and lateral dimension of 100 nm and 3–5 μm, respectively, demonstrated superior cycle performance as a negative electrode in lithium-ion batteries. A multi-folded layered structure with many voids was spontaneously formed in Si-LP composite electrodes by morphology changes of Si-LP sheets in repeated charge and discharge cycles. The multi-folded layered structure accommodated volumetric changes of the Si active material and prevented exfoliation of the active material from the current collector, which led to the superior long-term cyclability of the Si-LP electrode. The main factor for capacity fading in long-term cycling was a gradual loss of conduction pathways between Si-LP sheets due to the accumulation of electrolyte reduction products in the electrode. The film-forming additives, vinylene carbonate and fluoroethylene carbonate, effectively suppressed the electrolyte decomposition and remarkably improved the cycle performance of the Si-LP electrode.

We have developed a novel diastereoselective iron-catalyzed cross-coupling reaction of various glycosyl halides with aryl metal reagents for the efficient synthesis of aryl C-glycosides, which are of significant pharmaceutical interest due to their biological activities and resistance toward metabolic degradation. A variety of aryl, heteroaryl, and vinyl metal reagents can be cross-coupled with glycosyl halides in high yields in the presence of a well-defined iron complex, composed of iron(II) chloride and a bulky bisphosphine ligand, TMS-SciOPP. The chemoselective nature of the reaction allows the use of synthetically versatile acetyl-protected glycosyl donors and the incorporation of various functional groups on the aryl moieties, producing a diverse array of aryl C-glycosides, including Canagliflozin, an inhibitor of sodium-glucose cotransporter 2 (SGLT2), and a prevailing diabetes drug. The cross-coupling reaction proceeds via generation and stereoselective trapping of glycosyl radical intermediates, representing a rare example of highly stereoselective carbon-carbon bond formation based on iron catalysis. Radical probe experiments using 3,4,6-tri-O-acetyl-2-O-allyl-α-d-glucopyranosyl bromide (8) and 6-bromo-1-hexene (10) confirm the generation and intermediacy of the corresponding glycosyl radicals. Density functional theory (DFT) calculations reveal that the observed anomeric diastereoselectivity is attributable to the relative stability of the conformers of glycosyl radical intermediates. The present cross-coupling reaction demonstrates the potential of iron-catalyzed stereo- and chemoselective carbon-carbon bond formation in the synthesis of bioactive compounds of certain structural complexity.

A series of norvaline (Nva) peptides possessing ONO-pincer ruthenium complexes, Boc-{l-[Ru(pydc)(t-Bu-terpy)]Nva}n-OMe (n = 2–6), were synthesized successfully by solution-phase peptide synthesis. Efficient coupling of equimolar amounts of N-free Ru-bound norvaline peptides, H-{l-[Ru(pydc)(t-Bu-terpy)]Nva}n-OMe, and C-free Ru-bound norvaline, Boc-l-[Ru(pydc)(t-Bu-terpy)]Nva-OH, was achieved by using the 2-chloro-4,6-dimethoxy-1,3,5-triazine-based method. Structural analysis by means of CD and NMR spectroscopy revealed the formation of stable helical conformations in peptides more than three residues.

We studied the interaction between GroES and a single-ring mutant (SR1) of GroEL by the NMR titration of 15N-labeled GroES with SR1 at three different temperatures (20, 25 and 30°C) in the presence of 3 mM ADP in 100 mM KCl and 10 mM MgCl2 at pH 7.5. We used SR1 instead of wild-type double-ring GroEL to precisely control the stoichiometry of the GroES binding to be 1:1 ([SR1]:[GroES]). Native heptameric GroES was very flexible, showing well resolved cross peaks of the residues in a mobile loop segment (residue 17–34) and at the top of a roof hairpin (Asn51) in the heteronuclear single quantum coherence spectra. The binding of SR1 to GroES caused the cross peaks to disappear simultaneously, and hence it occurred in a single-step cooperative manner with significant immobilization of the whole GroES structure. The binding was thus entropic with a positive entropy change (219 J/mol/K) and a positive enthalpy change (35 kJ/mol), and the binding constant was estimated at 1.9×105 M−1 at 25°C. The NMR titration in 3 mM ATP also indicated that the binding constant between GroES and SR1 increased more than tenfold as compared with the binding constant in 3 mM ADP. These results will be discussed in relation to the structure and mechanisms of the chaperonin GroEL/GroES complex.

To compensate the large irreversible capacity (Qirr), lithium was pre-doped to Si thin flakes (Si Leaf Powder® (Si-LP), thickness: 100 nm) for different times, and its effects on the charge/discharge characteristics such as reversible capacity, cycleability, and rate-capability were investigated in detail. The charge/discharge test results showed that a large initial Qirr of ca. 2300 mAh g− 1 for the Si-LP can be completely compensated by Li pre-doping, and a high capacity (> 2500 mAh g− 1) was obtained for pre-doped Si-LPs. The pre-doping did not cause any harmful effects on cycleability as long as lithium was uniformly pre-doped. The addition of vinylene carbonate to the electrolyte solution in the pre-doping and in the test cell greatly improved the cycleability, and a high discharge capacity of ca. 2300 mAh g− 1 was kept after 40 cycles.

A PCP pincer palladium-complex-bound norvaline, Boc- l -[Pd]Nva-OMe, was synthesized and fully characterized by NMR, FT-ICR-MS, and X-ray crystallography. Selective N- and C-terminus transformations of Boc- l -[Pd]Nva-OMe were performed by conventional deprotection–condensation procedures to afford lipophilic palladium-bound norvaline derivatives without metal detachment. The N-/C-bisfunctionalized palladium-bound norvaline showed self-assembly properties, as evidenced by supramolecular gel formation. The catalytic activity of the supramolecular gel was assessed in the 1,4-conjugate addition of phenylboronic acid.

The NCN-pincer Pd-complex-bound norvalines Boc-D/L-[PdCl(dpb)]Nva-OMe (1) were synthesized in multigram quantities. The molecular structure and absolute configuration of 1 were unequivocally determined by single-crystal X-ray structure analysis. The robustness of 1 under acidic/basic conditions provides a wide range of N-/C-terminus convertibility based on the related synthetic transformations. Installation of a variety of functional groups into the N-/C-terminus of 1 was readily carried out through N-Boc- or C-methyl ester deprotection and subsequent condensations with carboxylic acids, R(1)COOH, or amines, R(2)NH2 , to give the corresponding N-/C-functionalized norvalines R(1)-D/L-[PdCl(dpb)]Nva-R(2) 2-9. The dipeptide bearing two Pd units 10 was successfully synthesized through the condensation of C-free 1 with N-free 1. The robustness of these Pd-bound norvalines was adequately demonstrated by the preservation of the optical purity and Pd unit during the synthetic transformations. The lipophilic Pd-bound norvalines L-2, Boc-L-[PdCl(dpb)]Nva-NH-n-C11H23, and L-4, n-C4H9CO-L-[PdCl(dpb)]Nva-NH-n-C11H23, self-assembled in aromatic solvents to afford supramolecular gels. The assembled structures in a thermodynamically stable single crystal of L-2 and kinetically stable supramolecular aggregates of L-2 were precisely elucidated by cryo-TEM, WAX, SAXS, UV/Vis, IR analyses, and single-crystal X-ray crystallography. An antiparallel β-sheet-type aggregate consisting of an infinite one-dimensional hydrogen-bonding network of amide groups and π-stacking of PdCl(dpb) moieties was observed in the supramolecular gel fiber of L-2, even though discrete dimers are assembled through hydrogen bonding in the thermodynamically stable single crystal of L-2. The disparate DSC profiles of the single crystal and xerogel of L-2 indicate different thermodynamics of the molecular assembly process.

Dimethylsulfoxide (DMSO)-quenched hydrogen/deuterium (H/D)-exchange is a powerful method to characterize the H/D-exchange behaviors of proteins and protein assemblies, and it is potentially useful for investigating non-protected fast-exchanging amide protons in the unfolded state. However, the method has not been used for studies on fully unfolded proteins in a concentrated denaturant or protein solutions at high salt concentrations. In all of the current DMSO-quenched H/D-exchange studies of proteins so far reported, lyophilization was used to remove D2O from the protein solution, and the lyophilized protein was dissolved in the DMSO solution to quench the H/D exchange reactions and to measure the amide proton signals by two-dimensional nuclear magnetic resonance (2D NMR) spectra. The denaturants or salts remaining after lyophilization thus prevent the measurement of good NMR spectra. In this article, we report that the use of spin desalting columns is a very effective alternative to lyophilization for the medium exchange from the D2O buffer to the DMSO solution. We show that the medium exchange by a spin desalting column takes only about 10 min in contrast to an overnight length of time required for lyophilization, and that the use of spin desalting columns has made it possible to monitor the H/D-exchange behavior of a fully unfolded protein in a concentrated denaturant. We report the results of unfolded ubiquitin in 6.0M guanidinium chloride.

Pure Si thin flakes (Si Leaf Powder® (Si-LP)) of different thicknesses (50, 100, 200, 300 and 400 nm) were prepared, and their charge/discharge properties were investigated as negative electrode materials for lithium ion batteries (LIBs). High reversible capacity (2200–2500 mAh g − 1 ) and good capacity retention were obtained for thinner Si-LPs (50–200 nm), while thicker samples (300 and 400 nm) exhibited rapid capacity fade upon cycling at C/6. For the thinner flakes, agglomeration and large cracks were confirmed on the composite electrodes, but no pulverization of the flakes was observed. These data suggested that Li atoms diffused easily within the thinner Si-LPs and the uniformity of Li distribution suppressed the localized physical stress that caused by alloying and de-alloying. In addition, the addition of vinylene carbonate (VC) in the electrolyte was found to be quite effective for improving not only the cycleability, but also the rate-capability. The best performance was obtained for Si-LP (100 nm), which exhibited a superior cycleability (ca. 2300 mAh g − 1 at C/6 after 50 cycles) and a high rate capability (ca. 1400 mAh g − 1 at 12 C rate).

Pure Si platelets and Ni or Cu layer-laminated Si platelets with difference thickness were prepared, and their charge/discharge properties were examined in 1 M LiClO 4 /EC + DEC (1:1 by volume) as alternative negative electrode materials to graphite for Li-ion batteries. The shape of thin platelets and lamination with Ni layer are significantly effective to improve the cycleability in Li–Si alloy system by relieving the stress during the alloying/de-alloying processes, reinforcing the mechanical strength and reducing the Li + ion diffusion length. Moreover, the first irreversible capacity is minimized by reduction of the amount of Ketjen Black (KB) in the composite electrode because of electrolyte decomposition on the surface of KB. Consequently, the Si/Ni/Si-LP30 (30/30/30 nm) composite electrode with 5 wt% KB also exhibits over 700 mAh g −1 even after 50 cycles in 1 M LiPF 6 /EC + DEC (1:1).

The compaction of gene-size T4 DNA induced by the action of silica nanoparticles (10–100 nm diameter), the surfaces of which were modified to various degrees by a 3-aminopropylsilyl groups, was mon...

At interconnection between a Ag-base conductor alloy and a Sn-base solder alloy, fast penetration of Sn into the conductor alloy occurs due to diffusion induced recrystallization (DIR) during solid-state heating under usual energization conditions. Like formation of binary Ag–Sn compounds, the penetration of Sn deteriorates the electrical conductivity at the interconnection. In order to examine the penetration rate of Sn into the conductor alloy, the kinetics of DIR in the Ag(Sn) system was experimentally observed in the present study. The experiment was carried out using Sn/Ag/Sn diffusion couples prepared by a diffusion bonding technique. The diffusion couples were isothermally annealed at temperatures of T ¼ 433{473 K for various times up to t ¼ 1100 h in an oil bath with silicone oil. Due to annealing, a region alloyed with Sn is formed in Ag due to DIR at T ¼ 453 and 473 K. At T ¼ 433 K, however, the DIR region could not be recognized clearly. The concentration of Sn in the DIR region is about half of the solubility of Sn in Ag. The mean thickness l of the DIR region reaches to 4 mm for t ¼ 1100 ha t T ¼ 453 K and 5 mm for t ¼ 890 ha tT ¼ 473 K. The experimental results were theoretically analyzed using mathematical models. The analysis indicates that the growth of the DIR region is controlled by the interface reaction at the moving boundary of the DIR region within the experimental annealing times. At longer annealing times, however, the interface reaction is no longer the bottleneck for migration of the moving boundary and the grain boundary diffusion across the DIR region governs the growth of the DIR region.

Influence of Ni on the kinetics of the reactive diffusion between Au and Sn was experimentally studied at solid-state temperatures. Binary Sn-Ni alloys with Ni concentrations of 1, 3 and 5 mass% were used to prepare sandwich (Sn-Ni)/Au/(Sn-Ni) diffusion couples by a diffusion bonding technique. The diffusion couples were isothermally annealed at temperatures of T= 433, 453 and 473 K for various times in an oil bath with silicone oil. After annealing, AuNiSn 8 , AuSn 4 , AuSn 2 and AuSn compound layers were observed to form at the (Sn-Ni)/Au interface in the diffusion couple. The total thickness l of the compound layers monotonically increases with increasing annealing time t according to the equation l = k(t/t 0 ) n , where t 0 is unit time, 1 s. The exponent takes values between n = 0.29 and 0.37 under the present annealing conditions. Such values of n < 0.5 indicate that the grain boundary diffusion contributes to the rate-controlling process and the grain growth occurs at certain rates. The higher the Ni concentration of the Sn-Ni alloy is, the faster the overall growth of the compound layers occurs. This means that Ni is an accelerator for the reactive diffusion between Au and Sn at solid-state temperatures. The acceleration effect of Ni becomes more remarkable at higher annealing temperatures. Such influence of Ni on the kinetics is mainly attributed to the dependencies of the growth rate of the AuNiSn 8 layer on the composition of the Sn-Ni alloy and the annealing temperature.

The kinetics of the reactive diffusion between Pd and Sn at solid-state temperatures was experimentally examined using Sn/Pd/Sn diffusion couples prepared by a diffusion bonding technique. The diffusion couples were isothermally annealed at temperatures of T = 433, 453 and 473 K for various times up to 300 h in an oil bath with silicone oil. After annealing, PdSn 4 , PdSn 3 and PdSn 2 compound layers were observed at T = 433 K, but only PdSn 4 and PdSn 3 layers were recognized at T = 453 and 473 K. The total thickness l of the Pd–Sn compound layers is mathematically described as a power function of the annealing time t as follows: l = k ( t / t 0 ) n , where t 0 is unit time, 1 s. The diameter d of the columnar grain in the compound layers is also expressed as a power function of the annealing time t : d = k d ( t / t 0 ) p . At T = 433–473 K, n is close to 0.5, and p takes values of 0.14–0.17. Such values of p indicate that the grain growth occurs at certain rates in the compound layers. Nevertheless, the total thickness l is almost proportional to the square root of the annealing time t . Thus, it is concluded that the volume diffusion is the rate-controlling process of the reactive diffusion between Pd and Sn.

The kinetics of the reactive diffusion between Cu and Sn at solid-state temperatures was experimentally examined using Sn/Cu/Sn diffusion couples prepared by a diffusion bonding technique. The diffusion couples were isothermally annealed at temperatures between T = 433 and 473 K for various times in an oil bath with silicone oil. Due to annealing, compound layers consisting of Cu 3 Sn and Cu 6 Sn 5 are formed at the Cu/Sn interface. In most of the annealed diffusion couples, grains of CuSnO exist in the Cu 6 Sn 5 layer. However, the CuSnO grain scarcely influences the growth behavior of the compound layers. The thickness of the Cu 6 Sn 5 layer is around twice greater than that of the Cu 3 Sn layer. The difference between their thicknesses slightly increases with increasing annealing temperature. At a constant temperature, the ratio of the thicknesses remains constant independent of the annealing time. The total thickness l of the compound layers monotonically increases with increasing annealing time t according to equation l = k ( t / t 0 ) n , where t 0 is unit time, 1 s. The observations provide n = 0.37, 0.43 and 0.50 at T = 433, 453 and 473 K, respectively. The value n = 0.5 indicates that the volume diffusion is the rate-controlling process for the reactive diffusion at T = 473 K. As the annealing temperature decreases, the grain boundary diffusion will contribute to the rate-controlling process. Thus, the values of n smaller than 0.5 yield that there is the contribution of the grain boundary diffusion and the grain growth occurs at certain rates at T = 433 and 453 K. Since the ratio between the thicknesses of the compound layers is kept constant during isothermal annealing, the same rate-controlling process is expected to work in both compound layers.

The kinetics of the solid-state reactive diffusion between binary Au-Ag alloys and Sn was experimentally examined using Sn/ Au 0 . 7 5 Ag 0 . 2 5 /Sn and Sn/Au 0 . 5 Ag 0 . 5 /Sn diffusion couples. The diffusion couples were prepared by a diffusion bonding technique and then isothermally annealed at temperatures of T = 393,433 and 473 K for various times up to 1272 h in an oil bath with silicone oil. Under the present experimental conditions, AuSn 4 and AuSn 2 compound layers were observed after annealing. Furthermore, fine particles of Ag 3 Sn were rather uniformly distributed in the Au-Sn compound layers. The total thickness I of the Au-Sn compound layers is expressed as a power function of the annealing time t as follows: l = k(t/t 0 ) n , where to is unit time, 1 s. Here, the exponent takes values of n = 0.34-0.40. The mean interdistance r of the Ag 3 Sn particles is also described as a power function of t: r = k r (t/t 0 ) p , where p = 0.28-0.43. Assuming that the interdistance r varies in proportion to the grain size of the Au-Ag compound during annealing, the rate-controlling process of the reactive diffusion was estimated. If the grain boundary diffusion across the Au-Sn compound layers is the only rate-controlling process, the values of n calculated from the equation n = (1 - p)/2 become smaller than the experimental values of n = 0.34-0.40. Consequently, both the volume diffusion and the grain boundary diffusion should contribute to the rate-controlling process of the reactive diffusion.

We studied hydrogen/deuterium-exchange reactions of peptide amide protons of GroES using two different techniques: (1) two-dimensional 1 H– 15 N transverse-optimized NMR spectroscopy and (2) the dimethylsulfoxide-quenched hydrogen-exchange method combined with conventional 1 H– 15 N heteronuclear single quantum coherence spectroscopy. By using these techniques together with direct heteronuclear single quantum coherence experiments, we quantitatively evaluated the exchange rates for 33 out of the 94 peptide amide protons of GroES and their protection factors, and for the remaining 61 residues, we obtained the lower limits of the exchange rates. The protection factors of the most highly protected amide protons were on the order of 10 6 –10 7 , and the values were comparable in magnitude to those observed in typical small globular proteins, but the number of the highly protected amide protons with a protection factor larger than 10 6 was only 10, significantly smaller than the numbers reported for the small globular proteins, indicating that significant portions of free heptameric GroES are flexible and natively unfolded. The highly protected amino acid residues with a protection factor larger than 10 5 were mainly located in three β-strands that form the hydrophobic core of GroES, while the residues in a mobile loop (residues 17–34) were not highly protected. The protection factors of the most highly protected amide protons were orders of magnitude larger than the value expected from the equilibrium unfolding parameters previously reported, strongly suggesting that the equilibrium unfolding of GroES is more complicated than a simple two-state or three-state mechanism and may involve more than a single intermediate.

We had reported that an amorphous silicon flake powder (Si LeafPowder®, Si-LP), of which the lateral dimension and the thickness were ~4 μm and 100 nm, respectively, demonstrated superior cycle performances.[1, 2] Cyclability of the Si-LP electrodes was successfully improved by an addition of solid electrolyte interface (SEI)-forming additives such as vinylene carbonate (VC) and fluoroethylene carbonate (FEC). However, the capacity-fading mechanism of the Si-LP electrodes has not been clarified. In order to understand the capacity fading of the Si-LP and effects of additives, variations of impedance components and the morphology changes were investigated. Test electrodes were composed of Si-LP (83.3 wt.%), Ketjen Black (5.6 wt.%) and carboxymethyl cellulose sodium salt (11.1 wt.%), and coated on a Cu foil. The loading of the Si-LP composite was approximately 0.4 mg cm-2. Electrolytes were 1 M LiPF6 dissolved in a mixture of ethylene carbonate and diethyl carbonate (EC+DEC, 1:1 by vol.) with and without additive of 10 wt.% VC or FEC. Charge and discharge tests were conducted at C/2 rate in the CC-CV mode between 1.5 and 0.02 V using a two-electrode coin-type cell. The electrochemical impedance spectroscopy (EIS) was performed using a three-electrode cell in which impedance spectra were obtained by applying an AC voltage of 10 mV over the frequency range of 0.03 Hz to 300 kHz. Surface and cross-sectional morphologies of the Si-LP electrodes after cycling were observed by a scanning electron microscope (SEM) without air exposure. Cyclability of the Si-LP electrodes in the electrolyte with and without FEC is shown in Fig. 1(a). Capacity retention for Si-LP electrode was substantially improved by the FEC-addition, although the discharge capacity at the 100th cycle decreased to 50% of the initial discharge capacity for the Si-LP electrode without FEC. To understand effects of the FEC-addition, EIS measurements were conducted and the SEI resistance (R SEI) was derived from the impedance spectra obtained at 0.1 V in the charging process. The SEI resistance for the Si-LP without FEC increased with increase in cycle number as shown in Fig. 1(b). By the FEC-addition, the SEI resistance was decreased and its increment with cycle number was substantially suppressed in comparison with the case of additive-free, indicating that reductive decomposition of the electrolyte on the Si-LP electrode was suppressed with a stable SEI film derived from FEC. Cross-sectional SEM images of the Si-LP electrodes after 10 and 30 cycles in the additive-free electrolyte are shown in Fig 1(c) and (d). Deposits of reductive products of the electrolyte were confirmed on Si-LPs. The amount of the deposition increased with cycle number, indicating a continuous decomposition of the electrolyte and a growth of SEI layer. The growth of the SEI layer lades an increment of the SEI resistance. Moreover, we found that the thickness of the Si-LP composite electrode was increased drastically by the growth of SEI layer and bending of Si-LPs, leading to a loss of the electric contact between the Si-LPs. Although Si-LPs bended after cycling, pulverization of Si-LPs was not observed. On the other hand, thinner SEI layer was observed on Si-LPs with the FEC-addition, and the expansion of the composite electrodes was suppressed. The stable SEI layer suppresses increment of the SEI resistance. Ensuring the electric-conducting path between active materials by the stable SEI layer is necessary to achieve a superior cycle performance of Si anodes. Acknowledgments: This work was supported by JST-ALCA-SPRING and JSPS-KAKENHI Grant Number 25820335 and 16H04649. References: [1] M. Saito et al., J. Power Sources, 196, 6637 (2011).; [2] M. Haruta et al., Electrochemistry, 83, 837 (2015). Figure 1

Introduction Si is expected to apply for lithium ion batteries as an anode material with a high capacity. However, Si anodes show poor cycleability caused by a pulverization of the Si particles due to large volume changes during charge and discharge cycles. Hence, we designed a nano-flake Si called Si LeafPowder® (Si-LP), which can relieve the physical stress caused by expansion and shrinkage of Si during alloying/dealloying reactions with lithium. A good cycleability of Si-LP with a thickness of 100 nm has been reported.1) On the other hand, S is a promising cathode material with a high capacity. Therefore, Si-S batteries are expected as a next generation electrochemical energy storage device. However, when S cathode is charged and discharged in a conventional ethylene carbonate (EC) based electrolyte, polysulfide anions dissolve into the electrolyte resulting in a poor cycleability. Recently, the dissolution of lithium polysulfide anions was successfully suppressed by using a solvate ionic liquid electrolyte, tri- or tetra-glyme and lithium salt (1:1) complex electrolyte2). We recently reported that cycleability of the Si-LP electrodes in the glyme-based electrolyte was improved by the addition of fluoroethylene carbonate (FEC), which has been recognized as an effective additive that forms a stable solid electrolyte interphase (SEI) on Si electrodes. 3). However, the capacity retention was inferior to the case of using EC based electrolyte. Therefore, we tried to form a pre-film on the Si-LP electrode with the FEC electrolyte prior to cycling to improve the cycleability in the glyme based electrolyte. Experimental The Si-LP composite electrodes consisted of 83.3 wt.% Si-LP, 5.6 wt.% Ketjen black, and 11.1 wt.% carboxymethyl cellulose sodium salt. The loading of the Si-LP composite on a Cu foil with the thickness of 20 mm was approximately 0.3 mg/cm2. The electrolyte was prepared by mixing a purified tetraglyme (G4) and lithium bis(trifluoromethansulfonyl)amide (Li[TFSA]) at the equimolar ratio in an Ar-filled glovebox (referred to as [Li(G4)][TFSA]). [Li(G4)][TFSA] was mixed with 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether (HFE) in a molar ratio of 1:4 to reduce the viscosity of the electrolyte (referred to as [Li(G4)][TFSA]/HFE). 10 wt.% FEC-added [Li(G4)][TFSA]/HFE was also prepared. The pre-film on the Si-LP electrode was formed by a charge and discharge pre-cycle in the 1 M LiPF6/FEC electrolyte with a coin-type two electrodes half-cell at C/6 rate (1C = 4200 mAh g-1), 30°C. The working and counter electrodes were the Si-LP electrode and a Li metal, respectively. Charge and discharge properties of the Si-LP electrodes with the pre-film were investigated in the additive-free [Li(G4)][TFSA]/HFE electrolytes. For comparison, the pristine Si-LP electrodes were cycled in the [Li(G4)][TFSA]/HFE with and without FEC at C/2 rate. The surface of the Si-LP electrodes after cycling was evaluated by SEM/EDX. Results and discussion Figure 1(a) and 1(b) show charge and discharge curves of the Si-LP electrodes in [Li(G4)][TFSA]/HFE without and with FEC, respectively. By the addition of FEC, the capacity retention at the 100th cycle was improved and polarization was reduced. However, the discharge capacity of the Si-LP electrode with FEC-addition decreased quickly after 100th cycle and the capacity retention at the 200th cycle was 38.4%. On the other hand, the Si-LP electrodes with the pre-film achieved a superior cycleability in [Li(G4)][TFSA]/HFE as shown in Figure 1(c); the capacity retention at the 200th cycle was 72.8%. This result implies that a stable SEI was formed by the pre-cycle in 1 M LiPF6/FEC electrolyte. From SEM/EDX analysis, the reductive decomposition of the electrolyte was suppressed by the presence of the pre-film, whereas on the Si-LP electrodes without the pre-film, SEI film with a large amount of F content was confirmed, indicating the decomposition of HFE. Formation of stable SEI is necessary to achieve a long cycle-life of Si anodes in the glyme-based electrolytes. References 1) M.Saito et al., Solid State Ionics, 225, 506 (2012). 2) K. Dokko et al., J. Electrochem. Soc., 160,A1304 (2013). 3) M. Haruta et al., Electrochemistry, 83,837 (2015). Acknowledgment This study was supported by JST-ALCA SPRING and JSPS-KAKENHI Grant Number 16H04649. Figure 1

We had reported that am amorphous silicon flake powder (Si LeafPowder®, Si-LP), of which the lateral dimension and the thickness were ~4 μm and 100 nm, respectively, demonstrated superior cycle performances.[1, 2] Cyclability of the Si-LP electrodes was successfully improved by an addition of solid electrolyte interface (SEI)-forming additives such as vinylene carbonate (VC) and fluoroethylene carbonate (FEC). However, the capacity fading mechanism of the Si-LP electrodes has not been clarified. In order to understand the capacity fading of the Si-LP, variations of impedance components and the surface morphology associated with a decomposition of the electrolytes were investigated. Test electrodes were composed of Si-LP (83.3 wt.%), Ketjen Black (5.6 wt.%) and carboxymethyl cellulose sodium salt (11.1 wt.%), and coated on a Cu foil. The loading of the Si-LP composite was approximately 0.4 mg cm-2. Electrolytes were 1 M LiPF6 dissolved in a mixture of ethylene carbonate and diethyl carbonate (EC+DEC, 1:1 by vol.) with and without additive of 10 wt.% VC or FEC. Charge and discharge tests were conducted at C/2 rate in the CC-CV mode between 1.5 and 0.02 V using a two-electrode coin-type cell. The electrochemical impedance spectroscopy (EIS) was performed using a three-electrode cell in which impedance spectra were obtained by applying an AC voltage of 10 mV over the frequency range of 0.03 Hz to 300 kHz. Surface and cross-sectional morphologies of the Si-LP electrodes after cycling were observed by a scanning electron microscope (SEM) without air exposure. Cyclability of the Si-LP electrodes is shown in Fig. 1(a). Capacity retention for Si-LP electrodes was substantially improved by the VC- and FEC-addition, although the discharge capacity at the 100th cycle decreased to 50% of the initial discharge capacity for the Si-LP electrode in the additive-free electrolyte. To understand effects of VC- and FEC-addition, EIS measurements were conducted. Impedance components of the SEI layer, the electronic contact and the charge transfer were derived from the impedance spectra obtained at 0.1 V in the charging process. The SEI resistance of the Si-LP in the additive-free electrolyte increased with increasing cycle number as shown in Fig. 1(b), and the contact resistance also increased. The increments of the SEI and contact resistances with cycle number were suppressed by the VC- and FEC-addition. A thick SEI layer, originated from a continuous decomposition of the electrolyte, was observed by SEM on the Si-LP cycled in the additive-free electrolyte. Furthermore, we found that the thickness of the Si-LP composite was increased drastically by the growth of SEI layer, leading to a loss of the electronic contact between the Si-LPs. On the other hand, thinner SEI layers were observed on the Si-LPs cycled in the VC- and FEC-added electrolytes, and the expansion of the electrodes was suppressed. The continuous decomposition of the electrolyte was prevented by the stable SEI layer formed from decomposition products of VC and FEC, and therefore the increments of the SEI and contact resistances with cycle were suppressed. Ensuring the electronic-conducting path between active materials by the stable SEI layer is necessary to achieve a superior cycle performance of Si anodes. Acknowledgments: This work was supported by JST-ALCA-SPRING and JSPS-KAKENHI Grant Number 25820335. References: [1] M. Saito et al., J. Power Sources, 196, 6637 (2011).; [2] M. Haruta et al., Electrochemistry, 83, 837 (2015). Figure 1

When a closed pipe filled with hot water is cooled, a cavity is generated in the pipe under pressure reduction due to large thermal contraction of water. In this paper, it was made clear that the transient response of pressure reduction in the above cooling cavitation shows the undershoot, and the response was modeled and formulated by the air desorption from the liquid into the cavity. The model parameters identified experimentally were investigated, and the time constant of air desorption sucked through the interface and the time constant of air diffusion within the liquid are obtained as the expressions in terms of the initial total air mass. Comparing the experimental and the calculated results, it was found that the minimum pressure and the final equilibrium pressure are proportional to the initial total air mass, and that the time at the minimum pressure is inversely proportional to the initial total air mass.

This paper presents some waveform analyses of the recorded pressure fluctuation in a water hammer due to collapse of a cooling cavity and the estimated velocity of the liquid column in collision with the blind end of a pipe. Real damping and peak period shortening, whose effects are similar in appearance on a graph of the change with time, are separated from each other by drawing graphs of the change with cycle number. The discussion on the damping is generalized using logarithmic decrements. It is proved that the air in the cavity strengthens the damping, the strengthening is greater earlier in the water hammer cycle, and the peak period shortening takes place rapidly not later than between the 2nd and the 3rd peaks in the case where the initial air concentration is over 30%, and is almost completed within this interval. In addition, considering the minor fluctuation in pressure bottoms, physical mechanisms of the damping and the peak period shortening are discussed.

Dimethylsulfoxide (DMSO)-quenched hydrogen/deuterium (H/D)-exchange is a powerful method to characterize the H/D-exchange behaviors of proteins and protein assemblies, and it is potentially useful for investigating non-protected fast-exchanging amide protons in the unfolded state. However, the method has not been used for studies on fully unfolded proteins in a concentrated denaturant or protein solutions at high salt concentrations. In all of the current DMSO-quenched H/D-exchange studies of proteins so far reported, lyophilization was used to remove D2 O from the protein solution, and the lyophilized protein was dissolved in the DMSO solution to quench the H/D exchange reactions and to measure the amide proton signals by two-dimensional nuclear magnetic resonance (2D NMR) spectra. The denaturants or salts remaining after lyophilization thus prevent the measurement of good NMR spectra. In this article, we report that the use of spin desalting columns is a very effective alternative to lyophilization for the medium exchange from the D2 O buffer to the DMSO solution. We show that the medium exchange by a spin desalting column takes only about 10 min in contrast to an overnight length of time required for lyophilization, and that the use of spin desalting columns has made it possible to monitor the H/D-exchange behavior of a fully unfolded protein in a concentrated denaturant. We report the results of unfolded ubiquitin in 6.0M guanidinium chloride.

A water hammer in collapse of a cooling cavity is modeled and formulated by making well-connections between the water hammer in liquid pipelines and the thermodynamics in the cavity, as a combination of the rigid column theory with the piston-cylinder system and in consideration of the gas in the cavity as moist air. Transient responses of the variables are calculated numerically, including the equation of energy and the term of heat transfer, with a correction for the area of heat transfer to the cavity shape and the identification of the coefficient of heat transfer on the basis of numerical stability. The high-damping waveforms of pressure fluctuation recorded in the experiment, which are not reproducible in the case of using only pipe friction and valve loss, are simulated adequately. Some physical interpretations for the numerical solutions are given and the dependency of solutions on the initial air concentration in the cavity is discussed.

This paper prenents some waveform analyses on the recorded pressure fluctuation in a waterhammer by collapse of a cooling cavity and the estimated collision velocity of the liquid column to the blind end of a pipe. Real damping and peak period shortening, whose effects are alike in appearance on a graph of the change with passage of time, are separated by means of graphs of the change with passage of cycle number. The discussion on the damping is generalized using logarithmic decrements. The obtained results are that the air in the cavity strengthens the damping, its strengthening is larger early in the waterhammer, and the peak period shortening takes place rapidly not later than between the 2nd and the 3rd peaks in the case where the initial air concentration is over 30% and is almost finished by the peak periods. In addition, taking note of the ripple of bottom pressure, the physical mechanisms of those damping and peak period shortening are discussed.

Nanoparticles, as nonviral vectors, have attracted attention for their ability in gene delivery and are currently considered to be prospective future vectors for biological and biomedical application . We prepared organically modified cationic silica nanoparticles toward the high performance nonviral vector. It is to be noted that the complexes of DNA and nanoparticles are regarded as a simple model of chromatin. Furthermore, it is reported that the transcription activity of DNA is preserved after complexing with small nanoparticles, where the manner of complex formation is strongly dependent on the size of the nanoparticles in vitro. On the other hand, it is confirmed that transcription is completely inhibited in the compact globule state of giant DNA induced by polyamines and related polycations. In the present study, we transfected the nonvel type nanoparticles into mammalican cells. It has been found that the nanoparticles are very effectively taken up by both cytoplasm and nucleus of cells according to the observation by fluorescence confocal microscopy. In addition, we have also demonstrated that the nanoparticles are non-toxic for cell. Furthermore, it is particularly important that almost 100% HeLa cells were observed incorporating nanoparticles which suggests that treatment of cells with these nanoparticles can secure uniform and total (in terms of cell population) filling of cells with the nanoparticles. The observed time dependence and size effect in the process of nanoparticles uptake by cells suggests that the scenario of nanoparticles uptake by cells can be programmed by varying size and time parameters. From all these findings, we consider that the nanoparticles may be used as a highly efficient and safe gene transfer vectors. As future work, we will investigate if the cationic silica nanoparticles can efficiently bind and transfect plasmid DNA. On the other hand, it is also interesting to study whether nanoparticles can make any change of the higher-order structure of genomic DNA, and hence the activity of transcription.

Two kinds of analog transformation methods for the measurement of high frequency pulsating flow rates in pipe flow are investigated. By use of the methods, the high frequency pulsating flow rates can be obtained by feeding differential pressure or centerline velocity to analog electronic circuits. First, the frequency characteristics of the electronic circuits for the measurement are examined by experiments. Then a criterion for determining the measurement distance of the differential pressure is derived analytically in order to ensure the required accuracy of the measurement when the flow rate is obtained from the differential pressure signal. Both methods are experimented with over a wide range of frequency. The results show that both methods are not only simple and practical, but also very accurate for the measurement of high frequency pulsating flow rates.

It is the purpose of this paper to point out that the classification of column separations in a horizontal water pipeline as an upstream-type, a midstream-type and a downstream-type is very useful for investigating column separations and analytical methods. Detailed experiments on column separations were conducted using an acrylic pipeline which was 200 m in length and 15.2 mm in diameter. Simulations of column separations by representative analytical methods were carried out. From comparisons of experimental results and calculated results, according to the classification, characteristics of column separations and analytical methods were identified very clearly.

Nanoparticles, as nonviral vectors, are expected as a candidate on highly effective non-viral gene carrier. We prepared organically modified cationic silica nanoparticles toward the high performance nonviral vector. It is to be noted that the complexes of DNA and nanoparticles are regarded as a simple model of chromatin. Furthermore, it is reported that the transcription activity of DNA is preserved after complexing with small nanoparticles, where the manner of complex formation is strongly dependent on the size of the nanoparticles in vitro. On the other hand, it is confirmed that transcription is completely inhibited in the compact globule state of giant DNA induced by polyamines and related polycations. The future goal of our undergoing studies is to make clear whether nanoparticles can be used for regulation of the higher-order structure of genomic DNA, and hence activate or inhibit transcription. In the present study, we performed experiments of transfecting nanoparticles into cell. Observation by fluorescence confocal microscopy shows that nanoparticles are effectively taken up in both cytoplasm and nucleus in cells. Importantly, it is also demonstrated that the nanoparticles are non-toxic for cell. The difference in the scenario of nanoparticles uptake by cells has been also observed. The results suggest that organically modified cationic silica nanoparticles may be the next new class of DNA binders and carries for biological and biomedical applications in the future.

Li-Si alloy is a promising high capacity anode; however, the poor cycleability should be improved for commercial applications. The poor cycleability has been attributed to a large volume during the charge/discharge cycling, resulting fracture and pulverization of Si particles. Therefore, relaxation of the physical stress is important to attain a good cycleability. It has been well recognized that Si nano-particles effectively reduces the stress by the expansion and shrinkage, which gives a good cycleability. However, the use of nano-particles results in a low packing density of the electrode. We designed Si nano-flakes called Si Leaf-Powder®(LP), which enables us to reduce the stress by the expansion and shrinkage and to make highly dense electrode composites. We prepared Si nano-flakes of different thickness (50-400 nm, Fig. 1) by a vapor phase deposition, and have investigated their charge and discharge characteristics [1-3]. Here we discuss the cycleability, the irreversible capacity, and the surface film (SEI) growth during cycling of the Si nano-flakes. The cycleability of Si-LPs of different thicknesses at C/6 in 1 M LiPF6/EC+DEC(1:1) +10 wt% VC is shown in Fig. 2 [1]. The cycleability of Si-LPs greatly depended on the thickness. Thinner samples (50-200 nm) showed relatively good cycleability, while thicker samples (300 and 400 nm) showed poor cycleability. For the thinner samples, the diffusion of metallic Li in the Si flakes is facile. The resulting uniform distribution of Li within the nano-flake during charging and discharging suppressed the physical stress and resulted in good cycleability. The large irreversible capacity (Q irr) of Si anodes is a serious problem for use in practical lithium-ion cells. The addition of VC does not reduce Q irr. The origin of the large Q irr has been attributed to the reduction of surface SiOx and solvent decomposition (and the following SEI formation), but such an extremely large Q irr of > 1000 mAh g-1is most probably owing to the latter phenomenon. We found that coating of Si-LPs with thin carbon layer is effective for reducing Q irr [2]. However, crack formation of the carbon layer decreased the Coulombic efficiency the initial cycles, and we concluded that further remarkable reduction of Q irr cannot be expected. To reduce Q irr, we also found that a pre-doping technique is effective. We can reduce Q irr practically to zero by the pre-doping technique, and we obtained good cycleability similar to that without pre-doping [3]. Figure 3 shows the variations of the discharge capacity and Coulombic efficiency of Si-LP (100 nm) upon a long-term cycle test. The Si-LP sample showed good cycleability up to the 500th cycle. The initial capacity was ca. 2000 mAh g-1, and gradually decreased to ca. 1500 mAh g-1at the 500 cycle. Unfortunately, the capacity suddenly dropped after the 560 cycle, the reason of which is not clear at present. Though Si-LP (100 nm) showed good cycleability in the long-term cycle test, we found another serious problem. The Coulombic efficiency was initially low and gradually increased to 98% at the 9th cycle and to 99% at the 80th cycle. It did not reach 100% even at the 500th cycle (99.8%). This fact indicates that solvent decomposition (and SEI growth) slowly proceeds and does not stop even at the 500thcycle. It is therefore important to completely suppress the solvent decomposition, e.g. by a good additive, for use in practical lithium-ion cells. Acknowledgment:This work was supported by JST (ALCA), Japan. References: [1] M. Saito et al., Solid State Ionics, 225, 506 (2012).; [2] T. Okubo et al., Electrochemistry, 80(10), 720 (2012).; [3] M. Saito et al., Extended Abstracts of The 38thConference on Solid State Ionics in Japan, 1A02, Kyoto (2012).

Silica nanoparticles, the surface of which was modified by a 3-aminopropylsilyl group, compacted gene-size DNA in aqueous solutions in the presence of Na+ or K+. The DNA-compaction efficiency of hi...

not Available.

not Available.

not Available.

Pure Si thin flakes (Si Leaf Powder® (Si-LP)) of different thicknesses (50, 100, 200, 300 and 400 nm) were prepared, and their charge/discharge properties were investigated as anode materials for lithium ion batteries (LIBs). Thickness of the thin Si-LP (100 nm) changed reversibly during charging and discharging, while the expanded thickness upon charging was kept after fully discharged for the thick one (300 nm), indicating insufficient Li de-alloying at C/6 rate. The slower kinetics for the thicker Si-LPs was also confirmed by examination of the open circuit potential (OCP) and the rate capability. These suggested that Li atoms diffused easily within the thinner Si-LPs and the uniform Li distribution suppressed the physical stress due to the Li alloying and de-alloying, resulting a good cycleability. In addition, addition of vinylene carbonate (VC) in electrolyte reduced charge transfer resistance of the Li alloying/de-alloying reaction and much more improved the cycleability of Si-LPs.

not Available.

not Available.

Pure Si platelets (Si-LP, thickness: 100 nm) and Ni layer-laminated Si platelets with different thicknesses (Si/Ni/Si-LP50 (50/50/50 nm) and Si/Ni/Si-LP30 (30/30/30 nm)) were prepared by a vapor deposition method, and their charge/discharge properties were investigated as alternative negative electrode materials to graphite for lithiumion batteries. The shape of thin platelet effectively relieved the stress during the alloying and de-alloying processes, and improved the charge/discharge cycleability as compared with a commercially available Si powder. In particular, the laminated platelet samples showed very good cycleability, probably because of a shorter diffusion length of Li+ ions in the Si layers and an improved mechanical strength by the presence of the Ni layer.