2,317 research outputs found
4,4′-(Ethene-1,2-diyl)dipyridinium bis[4-(2-carboxybenzoyl)benzoate]
In the crystal structure of the title compound, C12H12N2
2+·2C15H9O5
−, the cation has site symmetry with the mid-point of C=C bond located on an inversion center. The two benzene rings of the anion are oriented at a dihedral angle 85.87 (6)°. In the crystal, intermolecular O—H⋯O and N—H⋯O hydrogen bonds link the cations and anions into supramolecular double chains, which are further connected into a three-dimensional network through intermolecular C—H⋯O and π–π stacking between parallel pyridine rings [centroid–centroid distance = 3.4413 (12)Å] and between parallel benzene rings [centroid–centroid distance = 3.6116 (14)Å]
Compensatory sweating after restricting or lowering the level of sympathectomy: a systematic review and meta-analysis
OBJECTIVE: To compare compensatory sweating after lowering or restricting the level of sympathectomy. METHOD: A systematic review and meta-analysis were conducted of all randomized controlled trials published in English that compared compensatory sweating after lowering or restricting the level of sympathectomy. The Cochrane collaboration tool was used to assess the risk of bias, and the Mantel-Haenszel odds ratio method was used for the meta-analysis. RESULTS: A total of 11 randomized controlled trials were included, including a total of 1079 patients. Five of the randomized controlled trials studied restricting the level of sympathectomy, and the remaining six studied lowering the level of sympathectomy. CONCLUSIONS: The compiled randomized controlled trial results published so far in the literature do not support the claims that lowering or restricting the level of sympathetic ablation results in less compensatory sweating
Aqua(2,2′-bipyrimidine-κ2 N,N′)(succinato-κ2 O 1,O 4)copper(II) dihydrate
In the crystal structure of the title compound, [Cu(C4H4O4)(C8H6N4)(H2O)]·2H2O, the CuII atom is chelated by a 2,2′-bipyrimidine (bpm) ligand and a succinate anion in the basal plane; a water molecule in the apical position completes the slightly distorted square-pyramidal coordination geometry. Another carboxylate O atom from an adjacent complex is located in the opposite apical direction, with a Cu⋯O distance of 2.706 (3) Å, and is not considered as a bridging atom. Extensive O—H⋯O and O—H⋯N hydrogen bonding is present in the crystal structure
Interaction between Age and Obesity on Cardiomyocyte Contractile Function: Role of Leptin and Stress Signaling
OBJECTIVES: This study was designed to evaluate the interaction between aging and obesity on cardiac contractile and intracellular Ca2+ properties. METHODS: Cardiomyocytes from young (4-mo) and aging (12- and 18-mo) male lean and the leptin deficient ob/ob obese mice were treated with leptin (0.5, 1.0 and 50 nM) for 4 hrs in vitro. High fat diet (45% calorie from fat) and the leptin receptor mutant db/db obesity models at young and older age were used for comparison. Cardiomyocyte contractile and intracellular Ca2+ properties were evaluated including peak shortening (PS), maximal velocity of shortening/relengthening (+/- dL/dt), time-to-PS (TPS), time-to-90% relengthening (TR(90)), intracellular Ca2+ levels and decay. O2(-) levels were measured by dihydroethidium fluorescence. RESULTS: Our results revealed reduced survival in ob/ob mice. Aging and obesity reduced PS, +/- dL/dt, intracellular Ca2+ rise, prolonged TR(90) and intracellular Ca2+ decay, enhanced O2(-) production and p(47phox) expression without an additive effect of the two, with the exception of intracellular Ca2+ rise. Western blot analysis exhibited reduced Ob-R expression and STAT-3 phosphorylation in both young and aging ob/ob mice, which was restored by leptin. Aging and obesity reduced phosphorylation of Akt, eNOS and p38 while promoting pJNK and pIkappaB. Low levels of leptin reconciled contractile, intracellular Ca2+ and cell signaling defects as well as O2(-) production and p(47phox) upregulation in young but not aging ob/ob mice. High level of leptin (50 nM) compromised contractile and intracellular Ca2+ response as well as O2(-) production and stress signaling in all groups. High fat diet-induced and db/db obesity displayed somewhat comparable aging-induced mechanical but not leptin response. CONCLUSIONS: Taken together, our data suggest that aging and obesity compromise cardiac contractile function possibly via phosphorylation of Akt, eNOS and stress signaling-associated O2(-) release
Association between late-life depression or depressive symptoms and stroke morbidity in elders::a systematic review and meta-analysis of cohort studies
Uncovering User Interest from Biased and Noised Watch Time in Video Recommendation
In the video recommendation, watch time is commonly adopted as an indicator
of user interest. However, watch time is not only influenced by the matching of
users' interests but also by other factors, such as duration bias and noisy
watching. Duration bias refers to the tendency for users to spend more time on
videos with longer durations, regardless of their actual interest level. Noisy
watching, on the other hand, describes users taking time to determine whether
they like a video or not, which can result in users spending time watching
videos they do not like. Consequently, the existence of duration bias and noisy
watching make watch time an inadequate label for indicating user interest.
Furthermore, current methods primarily address duration bias and ignore the
impact of noisy watching, which may limit their effectiveness in uncovering
user interest from watch time. In this study, we first analyze the generation
mechanism of users' watch time from a unified causal viewpoint. Specifically,
we considered the watch time as a mixture of the user's actual interest level,
the duration-biased watch time, and the noisy watch time. To mitigate both the
duration bias and noisy watching, we propose Debiased and Denoised watch time
Correction (DCo), which can be divided into two steps: First, we employ a
duration-wise Gaussian Mixture Model plus frequency-weighted moving average for
estimating the bias and noise terms; then we utilize a sensitivity-controlled
correction function to separate the user interest from the watch time, which is
robust to the estimation error of bias and noise terms. The experiments on two
public video recommendation datasets and online A/B testing indicate the
effectiveness of the proposed method.Comment: Accepted by Recsys'2
Aquabis(2-amino-1,3-thiazole-4-acetato-κ2 O,N 3)nickel(II)
In the crystal structure of the title compound, [Ni(C5H5N2O2S)2(H2O)], the NiII cation is located on a twofold rotation axis and chelated by two 2-amino-1,3-thiazole-4-acetate (ata) anions in the basal coordination plane; a water molecule located on the same twofold rotation axis completes the distorted square-pyramidal coordination geometry. Intermolecular O—H⋯O and N—H⋯O hydrogen bonding, as well as π–π stacking between parallel thiazole rings [centroid–centroid distance 3.531 (8) Å], helps to stabilize the crystal structure
Novel superconducting structures of BH2 under high pressure
The crystal structures of boron hydrides in a pressure range of 50–400 GPa were studied using the genetic algorithm (GA) method combined with first-principles density functional theory calculations. BH4 and BH5 are predicted to be thermodynamically unstable. Two new BH2 structures with Cmcm and C2/c space group symmetries, respectively, were predicted, in which the B atoms tend to form two-dimensional sheets. The calculated band structures showed that in the pressure range of 50–150 GPa, the Cmcm-BH2 phase has very small gaps, while the C2/c-BH2 phase at 200–400 GPa is metallic. The superconductivity of the C2/c-BH2 structure was also investigated, and electron–phonon coupling calculations revealed that the estimated Tc values of C2/c-BH2 are about 28.18–37.31 K at 250 GPa
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