A study of allosteric binding behaviour of a 1,3-alternate thiacalix[4]arene-based receptor using fluorescence signal

A novel heteroditopic thiacalix[4]arene receptor L possessing 1,3-alternate conformation, which contains two pyrene moieties attached to the lower rim via urea linkages together with a crown ether moiety appended at the opposite side of the thiacalix[4]arene cavity, has been synthesized. The complexation behaviour of receptor L was studied by means of fluorescence spectra and ¹H NMR titration experiments in the presence of K⁺ ions and a variety of other anions. The results suggested that receptor L can complex efficiently via the urea cavity or the crown ether moiety, and a positive/negative allosteric effect operating in receptor L was observed

Monte Carlo Hamiltonian: Inverse Potential

The Monte Carlo Hamiltonian method developed recently allows to investigate ground state and low-lying excited states of a quantum system, using Monte Carlo algorithm with importance sampling. However, conventional MC algorithm has some difficulties when applying to inverse potentials. We propose to use effective potential and extrapolation method to solve the problem. We present examples from the hydrogen system.Comment: To appear in Communications in Theoretical Physic

Synthesis and inclusion behavior of a heterotritopic receptor based on hexahomotrioxacalix[3]arene

A heterotritopic hexahomotrioxacalix[3]arene receptor with the capability of binding two alkali metals and a transition metal in a cooperative fashion was synthesized. The binding model was investigated by using ¹H NMR titration experiments in CDCl₃–CD₃CN (10:1, v/v), and the results revealed that the transition metal was bound at the upper rim and the alkali metals at the lower and upper rims. Interestingly, the alkali metal ions Li⁺ and Na⁺ bind at the lower and upper rim respectively depending on the dimensions of the alkali metal ions versus the size of the cavities formed by the calix[3]arene derivative. The hexahomotrioxacalix[3]arene receptor acts as a heterotritopic receptor, binding with the transition metal ion Ag⁺ and the alkali metals ions Li⁺ and Na⁺. These findings were not applicable to other different sized alkali metals, such as K⁺ and Cs⁺

Synthesis of a ditopic homooxacalix[3]arene for fluorescence enhanced detection of heavy and transition metal ions

A pyrene-appended ratiometric fluorescent chemosensor L based on a synthetic approach of insulating the fluorophore from the ionophore by a specific molecular spacer has been synthesised and characterised. The fluorescence spectra changes of L suggested that the chemosensor can detect heavy and transition metal (HTM) ions ratiometrically and with variable sensitivity according to the substituents present. ¹H NMR titration experiments indicated that the three triazole ligands prefer binding with Hg²⁺, Pb²⁺ and Zn²⁺, resulting in a conformational change that produces monomer emission of the pyrene accompanied by the excimer quenching. However, the addition of Fe³⁺, which may be accommodated by the cavity of L, makes the pyrene units move closer to each other, and a discernible increase in the emission intensity of the static excimer is observed. Therefore, it is believed that the ditopic scaffold of the calix[3]arene as a specific molecular spacer here plays an important role in the blocking of the heavy atom effect of HTM ions by insulating the fluorophore from the ionophore given the long distance between the metal cation and the pyrene moiety

POIReviewQA: A Semantically Enriched POI Retrieval and Question Answering Dataset

Many services that perform information retrieval for Points of Interest (POI) utilize a Lucene-based setup with spatial filtering. While this type of system is easy to implement it does not make use of semantics but relies on direct word matches between a query and reviews leading to a loss in both precision and recall. To study the challenging task of semantically enriching POIs from unstructured data in order to support open-domain search and question answering (QA), we introduce a new dataset POIReviewQA. It consists of 20k questions (e.g."is this restaurant dog friendly?") for 1022 Yelp business types. For each question we sampled 10 reviews, and annotated each sentence in the reviews whether it answers the question and what the corresponding answer is. To test a system's ability to understand the text we adopt an information retrieval evaluation by ranking all the review sentences for a question based on the likelihood that they answer this question. We build a Lucene-based baseline model, which achieves 77.0% AUC and 48.8% MAP. A sentence embedding-based model achieves 79.2% AUC and 41.8% MAP, indicating that the dataset presents a challenging problem for future research by the GIR community. The result technology can help exploit the thematic content of web documents and social media for characterisation of locations

Support for Language Learners by Designing a Personalized Voice Assistant

This study analyzes the learning experience of studying foreign languages (FLs) and designs a personal voice assistant to support users. Learning FL is a big challenge. The challenge of learning a new language including how language is used is ‘influenced by’ or is a direct result of the context in which communication takes place. The author\u27s self-experience as an international student informs this study and provides access to a broad range of peers at the institution who have similar experiences. On the other hand, by utilizing voice assistant (VA), users build a relationship with VA and learners can understand multiple language backgrounds and cultures. Through in-depth interviews, participants—recruited from campus—were asked questions about why one wants to learn FL, how one learns FL, which tools one used to support learning, the challenges one meets with this experience, etc. This research asks about one’s learning experience and shares the researcher idea with VA utilizing it in supporting learning FL. This study does two sets of interviews with same group participants in order to collect interviewees’ experiences and feedback through the design process. In a sample size of 18 participants, this research understands how culture, background and environment influence FL learners’ experiences during studying a new language. Some interviewees live in foreign places and feel anxious using FL to communicate with native speakers. Some interviewees live in native and want to know more about FL’s different cultures locally. With this study, this author designs a personal voice assistant and supports learners with learning foreign languages

A pyrene-armed hexahomotrioxacalix[3]arene as a multi-sensor via synergistic and demetallation effects

A new pyrene-armed hexahomotrioxacalix[3]arene L has been synthesized, which exhibits a pronounced fluorescence enhancement response toward Cu²⁺ ions via a Zn²⁺ or Cd²⁺ triggered synergistic effect. Additionally, the L·Cu²⁺+ complex can subsequently serve as a sensor for F⁻ via anion-induced demetallation. The fluorescence responses by the input of Cu²⁺, Zn²⁺/Cd²⁺ and F⁻ can be constructed as a combinational logic gate which mimics a set of molecular traffic signals