Bipolaronic blockade effect in quantum dots with negative charging energy

We investigate single-electron transport through quantum dots with negative charging energy induced by a polaronic energy shift. For weak dot-lead tunnel couplings, we demonstrate a bipolaronic blockade effect at low biases which suppresses the oscillating linear conductance, while the conductance resonances under large biases are enhanced. Novel conductance plateau develops when the coupling asymmetry is introduced, with its height and width tuned by the coupling strength and external magnetic field. It is further shown that the amplitude ratio of magnetic-split conductance peaks changes from 3 to 1for increasing coupling asymmetry. Though we demonstrate all these transport phenomena in the low-order single-electron tunneling regime, they are already strikingly different from the usual Coulomb blockade physics and are easy to observe experimentally.Comment: 6 pages, 5 figure

6-(Trifluoro­meth­yl)pyrimidine-2,4(1H,3H)-dione monohydrate

The title compound, C5H3F3N2O2·H2O, was prepared by the reaction of ethyl 4,4,4-trifluoro-3-oxobutano­ate with urea. In the crystal, the 6-(trifluoro­meth­yl)pyrimidine-2,4(1H,3H)-dione and water mol­ecules are linked by N—H⋯O and O—H⋯O hydrogen bonds. A ring dimer structure is formed by additional inter­molecular N—H⋯O hydrogen bonds

6-Hy­droxy-4-(pyridin-3-yl)-5-(2-thienyl­carbon­yl)-6-trifluoro­meth­yl-3,4,5,6-tetra­hydro­pyrimidin-2(1H)-one

In the title compound, C15H12F3N3O3S, the pyrimidine ring adopts a half-chair conformation with the mean plane formed by the ring atoms excluding the C atom bonded to thio­phene-2-carbonyl group lying nearly perpendicular to the pyridine and thio­phene rings, making dihedral angles of 84.91 (4) and 87.40 (5)°, respectively. The dihedral angle between the pyridine and thio­phene rings is 54.44 (5)°. The crystal structure is stabilized by inter­molecular O—H⋯O and N—H⋯N hydrogen bonds and weak C—H⋯O inter­actions further consolidate the structure

catena-Poly[[[diaqua­bis(2-methyl-6-oxo-1,6-dihydro-3,4′-bipyridine-5-carbo­nitrile)copper(II)]-μ-sulfato] tetra­hydrate]

In the title polymer, {[Cu(SO4)(C12H9N3O)2(H2O)2]·4H2O}n, both the metal center and the sulfate anion are located on a twofold axis. The CuII ion is coordinated by two pyridyl N atoms from two symmetry-related organic ligands, two O atoms from two symmetry-related water mol­ecules, and two O atoms from two symmetry-related sulfate anions, resulting in a distorted octa­hedral geometry. The sulfate anions act as μ2-bridges and connect metal ions, forming a one-dimensional chain along the b axis. The three-dimensional crystal structure is established through inter­molecular N—H⋯O and O—H⋯O hydrogen bonds involving the organic ligands, sulfate anions, coordinated and uncoordinated water mol­ecules, and through π–π inter­acting 2-pyridone rings, with centroid–centroid separations of ca 3.96 Å and tilt angles of ca 2.62°

Synthesis and Evaluation of Novel Organogermanium Sesquioxides As Antitumor Agents

Five new organogermanium sesquioxides have been synthesized and characterized by elemental analysis and IR spectra. All the compounds were tested for antitumor activities against KB, HCT, and Bel cells in vitro. Compound 5 (γ-thiocarbamido propyl germanium sesquioxide) showed excellent antitumor activity, and its inhibition yield to KB, HCT, and Bel cells was 92.9%, 84.9%, and 70.9%, respectively. A rapid method was described for the labeling compound 5 with 99mTc, and the optimum labeling conditions were investigated. The labeling yield is above 90% in pH 7.0, 20°C, reaction time greater than 10 minutes, 1 mg of compound 5, and 0.075∼0.1 mg of SnCl2. The biodistribution of 99mTc labeled compound 5 in nude mice bearing human colonic xenografts was studied. The result showed that the tumor uptakes were 0.73, 0.97, 0.87, and 0.62 ID%/g at 1-hour, 3-hour, 6-hour, and 20-hour postinjection, respectively. T/NT (the uptake ratio for per gram of tumor over normal tissues) was 18.3 for tumor versus brain and 5.81 for tumor versus muscle at 20-hour postinjection. The tumor clearance was slow. The results showed that compound 5 may be developed to be a suitable cancer therapeutic agent

catena-Poly[[(2,9-dieth­oxy-1,10-phen­anthroline-κ2 N,N′)cadmium(II)]-di-μ-dicyan­amido-κ4 N 1:N 5]

In the title polymer, [Cd(C2N3)2(C16H16N2O2)]n, the CdII ion is coordinated by two N atoms from one 2,9-dieth­oxy-1,10-phenanthroline mol­ecule and four N atoms from four symmetry-related dicyanamide ions in a distorted octa­hedral geometry. In the 2,9-dieth­oxy-1,10-phenanthroline ligand, the O and C atoms of the eth­oxy groups are located almost in the plane defined by the phenanthroline ring system. Two dicyanamide ions bridge two CdII ions, which are located on a twofold axis, forming a one-dimensional zigzag chain along the [001] direction. The 2,9-dieth­oxy-1,10-phenanthroline mol­ecules act as bidentate terminal ligands. There are π–π inter­actions between polymeric chains, characterized by a centroid–centroid distance of 3.7624 (2) Å between the phenanthroline rings of two neighbouring chains

Famine exposure in early life increases risk of cataracts in elderly stage

BackgroundEpidemiological studies have shown that early-life nutritional deficiencies are associated with an increased risk of diseases later in life. This study aimed to explore the correlation between famine exposure during the early stages of life and cataracts.MethodsWe included 5,931 participants from the Chinese Longitudinal Healthy Longevity Survey (CLHLS) 2018 cross-sectional data in our study. Subjects were categorized into three groups by their age during the famine: adulthood group, school age famine exposure group, and teenage famine exposure group. Utilizing binary logistic regression models, we investigated the relationship between early-life famine exposure and cataracts.ResultsCompared to the adulthood group, both the school age exposure group (OR = 2.49, 95%CI = 1.89–3.27) and teenage exposure group (OR = 1.45, 95%CI = 1.20–1.76) had a heightened risk of developing cataracts in elderly stage. And the sex differences in the impact of famine during early years on elderly cataract risk were observed, particularly indicating a higher risk among women who experienced childhood famine compared to men with similar exposure.ConclusionFamine exposure during the early stages of life is associated with a heightened risk of developing cataracts in old age. To prevent cataracts in elderly individuals, particularly in females, measures should be taken to address nutritional deficiencies in these specific periods

Effects of sea-buckthorn leaves on performance and serum metabolic profiles in Altay lambs

In this study, the effects of sea-buckthorn (Hippophae rhamnoides L.) leaves (SL) on the biochemical parameters and metabolomic profiling in Altay lamb (Ovis aries) were observed. Sixty six-month-old male Altay lambs (body weight 28.0 ± 3.5 kg) were randomly assigned to four groups (n=15). The experimental groups were named as CON, 2.5%, 5.0% and 7.5%. The group CON, contained animals fed with a basal diet. Animals of the other groups were fed a treatment diet consisting of 2.5% (Group 2.5%), 5.0% (Group 5.0%) and 7.5% (Group 7.5%) SL. The experimental period lasted 56 days. The results showed that the average daily gain (ADG) and average daily feed intake (ADFI) increased with the increase in the levels of dietary SL. Dietary SL showed a direct relationship with total protein (TP), albumin, globulin and total cholesterol (TC) content of the experimental animals. However, an indirect relationship was observed between dietary SL and the concentration of urea nitrogen (UN). The concentrations of glucose, high-density lipoprotein cholesterol (HDL-C) and low-density lipoprotein cholesterol (LDL-C) showed quadratic change. Additional changes occurred in the endogenous metabolites involving multiple pathways. The pathways were tricarboxylic acid (TCA) cycle, the metabolism of protein and amino acid and the metabolism of fatty acid and steroid. The changes in metabolites primarily revealed an increase in amino acids and carbohydrates and a decrease in lipid metabolites. These findings provide a comprehensive insight into the effects of the metabolic aspects of sea-buckthorn leaves on Altay lambs. In addition, the present research results provide a better understanding to the development and utilization of sea-buckthorn as a healthy additive for small ruminant production.Keywords: Hippophae rhamnoides L., lamb, metabolomics, growth performance, serum parameter

FAST observations of an extremely active episode of FRB 20201124A: II. Energy Distribution

We report the properties of more than 800 bursts detected from the repeating fast radio burst (FRB) source FRB 20201124A with the Five-hundred-meter Aperture Spherical radio Telescope (FAST) during an extremely active episode on UTC September 25-28, 2021 in a series of four papers. In this second paper of the series, we mainly focus on the energy distribution of the detected bursts. The event rate initially increased exponentially but the source activity stopped within 24 hours after the 4th day. The detection of 542 bursts in one hour during the fourth day marked the highest event rate detected from one single FRB source so far. The bursts have complex structures in the time-frequency space. We find a double-peak distribution of the waiting time, which can be modeled with two log-normal functions peaking at 51.22 ms and 10.05 s, respectively. Compared with the emission from a previous active episode of the source detected with FAST, the second distribution peak time is smaller, suggesting that this peak is defined by the activity level of the source. We calculate the isotropic energy of the bursts using both a partial bandwidth and a full bandwidth and find that the energy distribution is not significantly changed. We find that an exponentially connected broken-power-law function can fit the cumulative burst energy distribution well, with the lower and higher-energy indices being $-1.22\pm0.01$ and $-4.27\pm0.23$, respectively. Assuming a radio radiative efficiency of $\eta_r = 10^{-4}$, the total isotropic energy of the bursts released during the four days when the source was active is already $3.9\times10^{46}$ erg, exceeding $\sim 23\%$ of the available magnetar dipolar magnetic energy. This challenges the magnetar models invoking an inefficient radio emission (e.g. synchrotron maser models).Comment: 26 pages, 7 figures, accepted for publication in Research in Astronomy and Astrophysic