150 research outputs found
A double-walled triangular metal-organic macrocycle based on a [Cu-2(COO)(4)] square paddle-wheel secondary building unit
A metal-organic macrocycle (MOM), [(Cu-2)(3)L-6(DMF)(2)(H2O)(4)], was prepared using a long and "pseudo-rigid" dicarboxylic acid, 1,4-bis(3-carboxylphenylethynyl) benzene (H2L), with some rotational flexibility, where the MOM has a double-walled triangular geometry with three Cu paddle-wheel secondary building units (SBUs) doubly connected by the ligands in a cis-conformation.close8
Transmetalations in two metal-organic frameworks with different framework flexibilities: Kinetics and core-shell heterostructure
While only a partially transmetalated network was observed in a rigidmetal-organic framework (MOF), not only a completely transmetalated isostructural network but also a partially transmetalated core-shell heterostructural network could be obtained in a flexible MOF by controlling the reaction conditions.close191
A two-fold interpenetrated (3,6)-connected metal-organic framework with rutile topology showing a large solvent cavity
A two-fold interpenetrated metal-organic framework (MOF), [(Zn(4)O)(2)L(4)(DMF)(2)(H(2)O)(3)], was prepared using the tritopic ligand 4,4',4 ''-[1,3,5-benzenetriyltris(carbonylimino)]trisbenzoic acid (H(3)L) and zinc nitrate. The MOF, based on the hexatopic tetranuclear Zn(4)O(COO)(6) secondary building unit, has a (3,6)-connected network with an rtl topology and a large solvent cavity.close302
Tree based Progressive Regression Model for Watch-Time Prediction in Short-video Recommendation
An accurate prediction of watch time has been of vital importance to enhance
user engagement in video recommender systems. To achieve this, there are four
properties that a watch time prediction framework should satisfy: first,
despite its continuous value, watch time is also an ordinal variable and the
relative ordering between its values reflects the differences in user
preferences. Therefore the ordinal relations should be reflected in watch time
predictions. Second, the conditional dependence between the video-watching
behaviors should be captured in the model. For instance, one has to watch half
of the video before he/she finishes watching the whole video. Third, modeling
watch time with a point estimation ignores the fact that models might give
results with high uncertainty and this could cause bad cases in recommender
systems. Therefore the framework should be aware of prediction uncertainty.
Forth, the real-life recommender systems suffer from severe bias amplifications
thus an estimation without bias amplification is expected. Therefore we propose
TPM for watch time prediction. Specifically, the ordinal ranks of watch time
are introduced into TPM and the problem is decomposed into a series of
conditional dependent classification tasks which are organized into a tree
structure. The expectation of watch time can be generated by traversing the
tree and the variance of watch time predictions is explicitly introduced into
the objective function as a measurement for uncertainty. Moreover, we
illustrate that backdoor adjustment can be seamlessly incorporated into TPM,
which alleviates bias amplifications. Extensive offline evaluations have been
conducted in public datasets and TPM have been deployed in a real-world video
app Kuaishou with over 300 million DAUs. The results indicate that TPM
outperforms state-of-the-art approaches and indeed improves video consumption
significantly
DNA vaccination with a gene encoding Toxoplasma gondii Deoxyribose Phosphate Aldolase (TgDPA) induces partial protective immunity against lethal challenge in mice
BACKGROUND: Toxoplasma gondii is an obligate intracellular parasite that causes a pathological status known as toxoplasmosis, which has a huge impact on human and animal health. Currently, the main control strategy depends on the usage of drugs that target the acute stage of the infection, however, drawbacks were encountered while applying this method; therefore, development of an alternative effective method would be important progress. Deoxyribose Phosphate Aldolase (TgDPA) plays an important role supporting cell invasion and providing energy for the parasite. METHODS: TgDPA was expressed in Escherichia coli and the purified recombinant protein was used to immunize rats. The antibodies obtained were used to verify in vitro expression of TgDPA. The vector pVAX1 was utilized to formulate a DNA vaccine designated as pTgDPA, which was used to evaluate the immunological changes and the level of protection against challenge with the virulent RH strain of T. gondii. RESULTS: DNA vaccine, TgDPA revealed that it can induce a strong humoral as well as cellular mediated response in mice. These responses were a contribution of T(H)1, T(H)2 and T(H)17 type of responses. Following challenge, mice immunized with TgDPA showed longer survival rates than did those in control groups. CONCLUSIONS: Further investigation regarding TgDPA is required to shed more light on its immunogenicity and its possible selection as a vaccine candidate
Discrete Conditional Diffusion for Reranking in Recommendation
Reranking plays a crucial role in modern multi-stage recommender systems by
rearranging the initial ranking list to model interplay between items.
Considering the inherent challenges of reranking such as combinatorial
searching space, some previous studies have adopted the evaluator-generator
paradigm, with a generator producing feasible sequences and a evaluator
selecting the best one based on estimated listwise utility. Inspired by the
remarkable success of diffusion generative models, this paper explores the
potential of diffusion models for generating high-quality sequences in
reranking. However, we argue that it is nontrivial to take diffusion models as
the generator in the context of recommendation. Firstly, diffusion models
primarily operate in continuous data space, differing from the discrete data
space of item permutations. Secondly, the recommendation task is different from
conventional generation tasks as the purpose of recommender systems is to
fulfill user interests. Lastly, real-life recommender systems require
efficiency, posing challenges for the inference of diffusion models. To
overcome these challenges, we propose a novel Discrete Conditional Diffusion
Reranking (DCDR) framework for recommendation. DCDR extends traditional
diffusion models by introducing a discrete forward process with tractable
posteriors, which adds noise to item sequences through step-wise discrete
operations (e.g., swapping). Additionally, DCDR incorporates a conditional
reverse process that generates item sequences conditioned on expected user
responses. Extensive offline experiments conducted on public datasets
demonstrate that DCDR outperforms state-of-the-art reranking methods.
Furthermore, DCDR has been deployed in a real-world video app with over 300
million daily active users, significantly enhancing online recommendation
quality
Cloning and characterization of a selenium-independent glutathione peroxidase (HC29) from adult Haemonchus contortus
The complete coding sequence of Haemonchus (H.) contortus HC29 cDNA was generated by rapid amplification of cDNA ends in combination with PCR using primers targeting the 5'- and 3'-ends of the partial mRNA sequence. The cloned HC29 cDNA was shown to be 1,113 bp in size with an open reading frame of 507 bp, encoding a protein of 168 amino acid with a calculated molecular mass of 18.9 kDa. Amino acid sequence analysis revealed that the cloned HC29 cDNA contained the conserved catalytic triad and dimer interface of selenium-independent glutathione peroxidase (GPX). Alignment of the predicted amino acid sequences demonstrated that the protein shared 44.7~80.4% similarity with GPX homologues in the thioredoxin-like family. Phylogenetic analysis revealed close evolutionary proximity of the GPX sequence to the counterpart sequences. These results suggest that HC29 cDNA is a GPX, a member of the thioredoxin-like family. Alignment of the nucleic acid and amino acid sequences of HC29 with those of the reported selenium-independent GPX of H. contortus showed that HC29 contained different types of spliced leader sequences as well as dimer interface sites, although the active sites of both were identical. Enzymatic analysis of recombinant prokaryotic HC29 protein showed activity for the hydrolysis of H2O2. These findings indicate that HC29 is a selenium-independent GPX of H. contortus
The Serine/Threonine-Protein Phosphatase 1 From Haemonchus contortus Is Actively Involved in Suppressive Regulatory Roles on Immune Functions of Goat Peripheral Blood Mononuclear Cells
Serine/threonine-protein phosphatases (STPs), as integral constituents of parasitic excretory/secretory proteins, are assumed to be released during the host–parasite interactions. However, knowledge about these phosphatases and their immunoregulatory and immune protective efficiencies with host peripheral blood mononuclear cells (PBMCs) is scant. In this study, an open reading frame of STP from Haemonchus contortus designated as HcSTP-1 was amplified and cloned using reverse-transcription-polymerase chain reaction (RT-PCR) method. The 951-bp nucleotides sequence was encoded to a protein of 316 amino acid residues, conserved in characteristics motifs GDXHG, GDYVDRG, GNHE, HGG, RG, and H. The HcSTP-1 protein was detected at approximately 35 kDa as recombinant protein fused in an expression vector system and resolved on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Immunohistochemically, HcSTP-1 was found to be localized in both male and female adult worm sections. Using immunofluorescence assay, the binding activity of rHcSTP-1 was confirmed on surface of goat PBMCs, which resulted in expression of multiple cytokines and various immunoregulatory activities in vitro. The RT-PCR results showed that mRNA level of interleukin-2, TGF-β1, IFN-γ, and IL-17 (with 10 µg/ml) was upregulated and IL-10 was decreased. However, IL-6 showed no change after PBMCs incubated with rHcSTP-1 protein. Further functional analysis showed that migratory activity of cells, intracellular nitrite production (NO), and apoptotic efficiency of PBMCs were elevated at significant level, whereas the proliferation of goat PBMCs and monocytes-associated major histocompatibility complex (MHC)-I and MHC-II expressions were decreased significantly at concentration-dependent fashion. Our results showed that the HcSTP-1 protein engaged in vital suppressive regulatory roles on host immune cells, which might represent a potential molecular target for controlling H. contortus infection in future
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