Na-ion dynamics in Quasi-1D compound NaV2O4

We have used the pulsed muon source at ISIS to study high-temperature Na-ion dynamics in the quasi-one-dimensional (Q1D) metallic antiferromagnet NaV2O4. By performing systematic zero-field and longitudinal-field measurements as a function of temperature we clearly distinguish that the hopping rate increases exponentially above Tdiff=250 K. The data is well fitted to an Arrhenius type equation typical for a diffusion process, showing that the Na-ions starts to be mobile above Tdiff . Such results makes this compound very interesting for the tuning of Q1D magnetism using atomic-scale ion-texturing through the periodic potential from ordered Na-vacancies. Further, it also opens the door to possible use of NaV2O4 and related compounds in energy related applications.Comment: Accepted for publication in Journal of Physics: Conference Series (2014

Measurement of intracellular pH by flow cytometry using pH sensitive fluorescence dye, and influence of hyperthermia and amiloride derivatives on the intracellular pH

エールリッヒ腹水癌細胞とそのアドリアマイシン耐性細胞において蛍光pH指示薬2'、7'-bis-(2-carboxyethyl) carboxyfluorescein] (BCECF) の蛍光量をフローサイトメトリーで測定することによって細胞内pHの検量曲線を作成することができた。このことより、これらの細胞においてBCECFの蛍光量で細胞内pHの変化を簡易に比較できることを示唆した。さらに、温熱、Na(+)/H(+) exchanger の阻害例であるアミロライド[3,5-diamino-6-chloro-N-(diaminomethylene) pyrazinecarboxamide]、およびアミロライド誘導隊MH-12-43[N-amidino-3-amino-6-chloro-5-(N-ethyliso-propylamino) pyrazinecarboxyamide] の細胞内pHへの影響をエールリッヒ腹水癌細胞で観察した。37℃では、0.5mMアミロライド、0.05mM　MH-12-43により細胞内pHは減少し、42℃処理によりさらに減少した。42℃において、0.05mM　MH-12-43による細胞内pHの減少は、0.5mMアミロライドによる減少より大きかった。We examined relationship between intensity of intracellular fluorescence of [2', 7'-bis-(2'-carboxyethyl) carboxyfluorescein] (BCECF) and intracellular pH in Ehrlich ascites tumor cells and their adriamycin-resistant strain, and found a good correlation between them at both strains. This suggests that changes in the intracellular pH on these strains may be obtained through measurement of intracellular fluorescence of BCECF by flow cytometry. Further, we examined influence of hyperthermia, 3, 5-diamino-6-chloro-N-(diaminomethylene)pyrazinecarboxamide (amiloride), an inhibitor of Na(+)/H(+) exchanger, and its derivative; N-amidino-3-amino-6-chloro-5-(N-ethylisopropylamino) pyrazinecarboxyamide (MH-12-43) on the intracellular pH in Ehrlich ascites tumor cells. The treatment of 0.5mM amiloride or 0.05mM MH-12-43 reduced intracellular pH at 37℃, while the more reduction was observed by the treatment at 42℃. The reduction of intracellular pH by 0.05mM MH-12-43 was more substantial than that of 0.5mM amiloride at 42℃

加温後のtsAF8細胞の細胞周期

Thermotolerance in tsAF8 cells develops during incubation at 34℃ after heating at 45℃, while it is suppressed by the following incubation at a non-permissive temperature of 39.7℃ after the same heating. The incubation temperature after heating may affect the cell cycle and consequently thermotolerance. In the present study, a relationship between the thermotolerance and the cell cycle of tsAF8 was investigated. The cell cycle fractions and DNA synthesis were measured by flow cytometry using double staining with propidium iodide and bromodeoxyuridine. When the tsAF8 cells were heated at 45℃ for 20 min, and thereafter incubated at 34℃, bromodeoxyuridine uptake in the S phase cells (DNA synthesis) was recovered to 65.1% 6 h after the heating, and the cells showed gradual accumulation in the G(2)/M phase. When the cells were incubated at 39.7℃ after heating at 45℃ for 20 min, then showed inhibition of thermotolerance development, the DNA synthesis was recovered to 15.1% temporarily 6 h after the heating, but it became 0% after 12 h, and the cells did not remarkably accumulate in any phases of the cell cycle. This inhibition of DNA synthesis at 39.7℃ was considered to be the result of cell survival decreasing by a step-down heating. However, the relationship between the thermotolerance and the cell cycle was not found out in tsAF8 cells, because the cells did not accumulate in any phases of the cell cycle under the inhibitory condition of thermotolerance.tsAF8細胞は45℃の加温後34℃で培養すると温熱耐性が速やかに発現するが,加温後,制限温度である39.7℃で培養すると温熱耐性の発現が抑制される｡加温後の培養温度が細胞周期に影響し,その結果として温熱耐性発現に影響を与えている可能性があることから,今回,Propidium Iodide(PI)とbromodeoxyuridine(BrdU)でtsAF8細胞を二重染色し,フローサイトメトリーによって温熱耐性と細胞周期の関係の有無について調べた｡tsAF8細胞を45℃20分の加温後34℃で培養すると,6時間後にはG(1)期の細胞が減少し,12時間後にはG(2)/M期への蓄積が見られた｡しかし,加温後39.7℃で培養した場合には細胞周期の進行がほとんど見られなかった｡BrdU の取込みは,加温せずに39.7℃で培養した場合には活発に行われ,また,45℃20分加温後34℃で培養した場合には,6時間後にはBrdUの取り込みは65.1%まで回復した｡しかし,温熱耐性発現の抑制が観察される45℃20分加温後39.7℃で培養した場合には,BrdUの取込み量は6時間後に一時的に15.1%に回復するが,12時間後には取込み量はゼロとなった｡BrdUの取り込みが阻害されたのはstep-down heatingの現象による細胞生存率の減少が原因だと考えられたが,温熱耐性発現の抑制が観察される条件下では細胞周期の特定の時期への集積がなかったことから,温熱耐性と細胞周期との関係はtsAF8細胞においては見い出されなかった

Relationship between intracellular uptake of adriamycin and membrane potential in ADR resistant Ehrlich ascites tumor cells

We observed adiamycin (ADR) uptake and cellular transmembrane potential [amount of intracellular fluorescence of 3,3'- (Di-n-hexyl)- 2,2'- oxacarbocyanine iodide (NK-2280)] in ADR-resistant cells established from Ehrlich ascites tumor cells (EATC) and wild type EATC. In ADR-resistant cells, ADR uptake and the cellular transmembrane potential decreased as the degree of resistance increased. 4,4'- diisothiocyanatostilbene- 2,2'- disulfonic acid (DIDS) induced markedly decreases of ADR uptake and the cellular transmembrane potential. A good correlation was observed between ADR uptake and transmembrane potential in cultured cells

Robust Single-Shot Spin Measurement with 99.5% Fidelity in a Quantum Dot Array

We demonstrate a new method for projective single-shot measurement of two electron spin states (singlet versus triplet) in an array of gate-defined lateral quantum dots in GaAs. The measurement has very high fidelity and is robust with respect to electric and magnetic fluctuations in the environment. It exploits a long-lived metastable charge state, which increases both the contrast and the duration of the charge signal distinguishing the two measurement outcomes. This method allows us to evaluate the charge measurement error and the spin-to-charge conversion error separately. We specify conditions under which this method can be used, and project its general applicability to scalable quantum dot arrays in GaAs or silicon.Comment: 13 pages, 3 figure

Quantum nondemolition measurement of an electron spin qubit

Measurement of quantum systems inevitably involves disturbance in various forms. Within the limits imposed by quantum mechanics, however, one can design an "ideal" projective measurement that does not introduce a back action on the measured observable, known as a quantum nondemolition (QND) measurement. Here we demonstrate an all-electrical QND measurement of a single electron spin in a gate-defined quantum dot via an exchange-coupled ancilla qubit. The ancilla qubit, encoded in the singlet-triplet two-electron subspace, is entangled with the single spin and subsequently read out in a single shot projective measurement at a rate two orders of magnitude faster than the spin relaxation. The QND nature of the measurement protocol is evidenced by observing a monotonic increase of the readout fidelity over one hundred repetitive measurements against arbitrary input states. We extract information from the measurement record using the method of optimal inference, which is tolerant to the presence of the relaxation and dephasing. The QND measurement allows us to observe spontaneous spin flips (quantum jumps) in an isolated system with small disturbance. Combined with the high-fidelity control of spin qubits, these results pave the way for various measurement-based quantum state manipulations including quantum error correction protocols.Comment: This is a pre-print of an article published in Nature Nanotechnology. The final authenticated version is available online at: https://doi.org/10.1038/s41565-019-0426-

Using Fully Homomorphic Encryption for Statistical Analysis of Categorical, Ordinal and Numerical Data

In recent years, there has been a growing trend towards outsourcing of computational tasks with the development of cloud services. The Gentry’s pioneering work of fully homomorphic encryption (FHE) and successive works have opened a new vista for secure and practical cloud computing. In this paper, we consider performing statistical analysis on encrypted data. To improve the efficiency of the computations, we take advantage of the batched computation based on the Chinese-Remainder-Theorem. We propose two building blocks that work with FHE: a novel batch greater-than primitive, and matrix primitive for encrypted matrices. With these building blocks, we construct secure procedures and protocols for different types of statistics including the histogram (count), contingency table (with cell suppression) for categorical data; k-percentile for ordinal data; and principal component analysis and linear regression for numerical data. To demonstrate the effectiveness of our methods, we ran experiments in five real datasets. For instance, we can compute a contingency table with more than 50 cells from 4000 of data in just 5 minutes, and we can train a linear regression model with more than 40k of data and dimension as high as 6 within 15 minutes. We show that the FHE is not as slow as commonly believed and it becomes feasible to perform a broad range of statistical analysis on thousands of encrypted data

STRENGTHENING OF SAND CEMENTED WITH CALCIUM PHOSPHATE COMPOUNDS USING PLANT-DERIVED UREASE

ABSTRACT: The effect of plant-derived urease enzyme to induce the precipitation of calcium phosphate compounds (CPCs) and hence, to improve the unconfined compressive strength (UCS) of sand was examined as a novel, eco-friendly ground improvement method. Initially, Toyoura sand test pieces were cemented only from CPC solution. Furthermore, another sand test pieces were cemented by different concentrations of urea, concentration fixed plant seeds extract (Watermelon) to obtain optimal cementation, and different concentrations of CPC solutions made from calcium and phosphate stock solutions. All test pieces were cured up to 28 days in an airtight container at high humidity at 25 o C. The UCS tests and scanning electron microscope (SEM) observations of sand test pieces were carried out. The UCS of test pieces cemented with CPC and plant extract were significantly higher than that of test pieces cemented without plant extract and increases with time. The best ratio of Ca: P in CPC solution was 0.75 M: 1.5 M, reaching a maximum UCS of 125.6 kPa after 28 days of curing. In addition, pH concentration was measured after UCS test and it has increased with time. Results indicate that the best pH for optimal cementation is 8.0. A specific crystal structure could not be identified from SEM observations in the segments of the test pieces cemented with CPC in all cases in this study. These results suggest that the addition of plant extract to CPC significantly enhances the mechanical properties of sand

Age-dependent motor dysfunction due to neuron-specific disruption of stress-activated protein kinase MKK7.

c-Jun N-terminal kinase (JNK) is a member of the mitogen-activated protein kinase family and controls various physiological processes including apoptosis. A specific upstream activator of JNKs is the mitogen-activated protein kinase kinase 7 (MKK7). It has been reported that MKK7-JNK signaling plays an important regulatory role in neural development, however, post-developmental functions in the nervous system have not been elucidated. In this study, we generated neuron-specific Mkk7 knockout mice (MKK7 cKO), which impaired constitutive activation of JNK in the nervous system. MKK7 cKO mice displayed impaired circadian behavioral rhythms and decreased locomotor activity. MKK7 cKO mice at 8 months showed motor dysfunctions such as weakness of hind-limb and gait abnormality in an age-dependent manner. Axonal degeneration in the spinal cord and muscle atrophy were also observed, along with accumulation of the axonal transport proteins JNK-interacting protein 1 and amyloid beta precursor protein in the brains and spinal cords of MKK7 cKO mice. Thus, the MKK7-JNK signaling pathway plays important roles in regulating circadian rhythms and neuronal maintenance in the adult nervous system