121 research outputs found
Impurity Substitution Effect on Magnetoelectric Properties of CaBaCo4O7 Crystals
AbstractWe have investigated effects of impurity substitution of Fe for Co sites on magnetic and dielectric properties in CaBa(Co1-xFex)4O7 crystals in magnetic fields. The non-doped compound, CaBaCo4O7 with the polar space group Pbn21, shows a large change of electric polarization ĪP along the c axis below a ferrimagnetic transition temperature. With increasing x, the transition temperatures for the ferrimagnetic and ferroelectric-like phases are shifted towards lower and these phases are completely collapsed above x=1.56%. We have also investigated the magnetic field effects for CaBa(Co1-xFex)4O7 crystal with a doping level x=0.5% where the ferrimagnetic and ferroelectric-like phases sustain. Then a relatively large magnetocapacitance, ĪÉ(H)/É(0) [É(H) ā É(0)]/É(0), of 45% at 58K was observed, which is not significantly reduced from the parent compound
Total synthesis of palauāamine
Palauāamine has received a great deal of attention in the past two decades as an attractive synthetic target by virtue of its intriguing molecular architecture and significant immunosuppressive activity. Here we report the total synthesis of palauāamine characterized by the construction of an ABDE tetracyclic ring core including a trans-bicylo[3.3.0]octane skeleton at a middle stage of total synthesis. The ABDE tetracyclic ring core is constructed by a cascade reaction of a cleavage of the NāN bond, including simultaneous formation of imine, the addition of amide anion to the resulting imine (D-ring formation) and the condensation of pyrrole with methyl ester (B-ring formation) in a single step. The synthetic palauāamine is confirmed to exhibit excellent immunosuppressive activity. The present synthetic route has the potential to help elucidate a pharmacophore as well as the mechanistic details of immunosuppressive activity
STM/STS study on electronic superstructures in the superconducting state of high-T-c cuprate Bi2Sr2CaCu2O8+delta
We report STM/STS measurements at 8 K in underdoped Bi2Sr2CaCu2O8+delta crystals (T-c = 76 K and hole-doping level p similar to 0.12) whose energy spectra around the Fermi level are characterized by a two-gap structure consisting of spatially inhomogeneous pseudogap (PG) and comparatively homogeneous superconducting gap (SCG). Two electronic superstructures, checkerboard modulation (CBM) and Cu-O-Cu bond-centered modulation (BCM), are observed with mapping spectral weights at low energies within the SCG and the ratio of spectral weights at +/-Delta(PG) (PG energy), respectively. On the basis of the present findings, we suggest that the lower-energy scale CBM is an intrinsic property of Cu-O planes and can coexist with the BCM whose characteristic energy is similar to Delta(PG) in identical regions in real space
Effects of arterial carbon dioxide manipulation on cerebral oxidative metabolism during hemorrhagic hypotension in dogs
[Background] : Development of brain acidosis is concerned during prolonged hemor- rhagic hypotension due to blood-brain barrier disruption, even though cerebral blood flow is maintained. There is possibility that PaC02 manipulation affects brain acidosis induced deterioration of cerebral oxidative metabolism by influencing the brain acid- base equilibrium. [Methods] : A dog model of hemorrhagic hypotension was used. Mean arterial pressure was kept at the lower limit of autoregulation to assure maintained cerebral blood flow. One of three different PaC02 manipulations, hypocapnia, normocapnia or hy-percapnia, was applied during hypotension and the effect of PaC02 manipulations on cerebral oxidative metabolism was estimated. [Results] : Cerebral blood flow and cerebral metabolic rate for oxygen remained unal-tered during hypotension. Brain acidosis was developed regardless of the PaC02 ma-nipulation used, being most acidotic with hypercapnia. Hypercapnia was accompanied by a significant decrease in phosphocreatinine and an increase in the L/P ratio com-pared to hypocapnia and normocapnia. [Conclusions] : PaC02 manipulation differentially affects cerebral oxidative metabolism during hemorrhagic hypotension with preserved cerebral blood flow, being worse with hypercapnia
Asymmetric Total Syntheses and Structure Revisions of Eurotiumide A and Eurotiumide B, and Evaluation of their Fluorescent Properties as Natural Probes
Asymmetric total syntheses and structure revisions of dihydroisocoumarin-type natural products, eurotiumide A and eurotiumide B have been described. The key features of these total syntheses are the asymmetric Shi epoxidation, regio and stereo-selective epoxide opening, C1 insertion/lactonization cascade reaction for constructing 4-methoxyisochroman-1-one skeleton. We confirmed the structures and configurations of eurotiumide A and B on the basis of X-ray crystallographic analysis of the key intermediate, and revealed that eurotiumide A and B have cis and trans configurations at H3/H4 positions, which are the opposite relationship of the stereochemistry from the previous report, respectively. The absolute configurations of them are also determined. These natural products exhibited highly fluorescence in several solvents with large Stokes shifts involving the excited-state intramolecular proton transfer mechanism, which is supported by time-dependent density functional theory. Eurotiumide A also emitted fluorescence in Bacillus cereus
A suitable stereoisomer of vibrioferrin probes for iron uptake of Vibrio parahaemolyticus
Suitable Stereostructures of vibrioferrin probes for iron uptake of Vibrio parahaemolyticus was revealed. Stereoisomers of dansyl labeled vibrioferrin at the 2ā²ā²-position were synthesized and their uptake activities were evaluated. Vibrio parahaemolyticus take in both isomers at the 2ā²ā²-position. In addition to Vibrio parahaemolyticus, several bacteria have also taken up the (R)-isomer
Synthesis and Antimicrobial Evaluation of Side-Chain Derivatives based on Eurotiumide A
Side-chain derivatives of eurotiumide A, a dihydroisochroman-type natural product, have been synthesized and their antimicrobial activities described. Sixteen derivatives were synthesized from a key intermediate of the total synthesis of eurotiumide A, and their antimicrobial activities against two Gram-positive bacteria, methicillin-susceptible and methicillin-resistant Staphylococcus aureus (MSSA and MRSA), and a Gram-negative bacterium, Porphyromonas gingivalis, were evaluated. The results showed that derivatives having an iodine atom on their aromatic ring instead of the prenyl moiety displayed better antimicrobial activity than eurotiumide A against MSSA and P. gingivalis. Moreover, we discovered that a derivative with an isopentyl side chain, which is a hydrogenated product of eurotiumide A, is the strongest antimicrobial agent against all three strains, including MRSA
A Long-term Survivor after Congenital Acute Myeloid Leukemia with t(8 ; 16)(p11 ; p13)
The treatment of patients with congenital leukemia is difficult and often results in a poor prognosis. We present here the case of a female child with congenital acute myeloid leukemia (AML) with t(8 ; 16) (p11 ; p13) who received chemotherapy and survived for more than 10 years without relapse. A novel MOZ-CBP chimera was found in her diagnostic sample. Although adult AML patients with MOZ-CBP have mainly been reported as having therapy-related AML and showed poor prognoses, the present case supports the idea that AML with MOZ-CBP in the pediatric population might show better prognoses
Trends and characteristics of severe road traffic injuries in children: a nationwide cohort study in Japan
Purpose: The purpose of this study was to evaluate temporal trends of characteristics of severe road traffic injuries in children and identify factors associated with mortality using a nationwide database in Japan. Methods: We performed a retrospective analysis of Japan Trauma Data Bank (JTDB) from 2004 to 2018. We included patients with traffic injuries under the age of 18 who were hospitalized. The primary outcome was in-hospital mortality. We evaluated trends in characteristics and assessed factors associated with in-hospital mortality using a logistic regression analysis. Results: A total of 4706 patients were analyzed. The most common mechanism of injury was bicycle crash (34.4%), followed by pedestrian (28.3%), and motorcycle crash (21.3%). The overall in-hospital mortality was 11.2%. We found decreasing trends in motorcycle crash and in-hospital mortality and increasing trends in rear passenger seats in cars over the 15-year period. The following factors were associated with in-hospital mortality: car crash (aOR 1.69, 95%CI 1.18ā2.40), pedestrian (aOR 1.50, 95%CI 1.13ā1.99), motorcycle crash (aOR 1.42, 95%CI 1.03ā1.95) [bicycle crash as a reference]; concomitant injuries to head/neck (aOR 5.06, 95%CI 3.81ā6.79), thorax (aOR 2.34, 95%CI 1.92ā2.87), abdomen (aOR 1.74, 95%CI 1.29ā2.33), pelvis/lower-extremity (aOR 1.57, 95%CI 1.23ā2.00), spine (aOR 3.01, 95%CI 2.02ā4.43); and 5-year increase in time period (aOR 0.80, 95%CI 0.70ā0.91). Conclusions: We found decreasing trends in motorcycle crash and in-hospital mortality, increasing trends in rear passenger seats in cars over the 15-year period, and factors associated with in-hospital mortality such as type of mechanisms and concomitant injuries. Strengthening child road safety measures, particularly for rear passenger seats in vehicles, is imperative to enhance our dedication to injury prevention.The version of record of this article, first published in European Journal of Trauma and Emergency Surgery, is available online at Publisherās website: https://doi.org/10.1007/s00068-023-02372-
Inactivation of the Influenza Virus by a Supplemental Fermented Plant Product (Manda Koso)
Manda Koso is a commercial fermented plant product (FPP) made from 53 types of fruits and vegetables that are fermented for more than 3 years. We hypothesized that the FPP can prevent infection by influenza virus and human norovirus. Therefore, we investigated the effects of the FPP on influenza virus and feline calicivirus, a surrogate of human norovirus. We found that 10% FPP inactivated the influenza virus but not the feline calicivirus. Inhibition of the influenza virus was highly concentration-dependent: 1% and 0.3% FPP showed reduced inactivation efficacy. The effects of the FPP on the influenza virus-infected cells were investigated by addition of the FPP to the culture medium after virus infection. No suppressive effect of the FPP on influenza replication in MDCK cells was observed. The results showed that the FPP could inactivate influenza virus by affecting the virus particles
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