FUNDAMENTAL INVESTIGATION ON ANION BINDING EMPLOYING THE HYDROGEN BOND ENHANCED HALOGEN BOND

Noncovalent interactions play a critical role in chemistry and biochemistry. Understanding how to modulate closely situated noncovalent interactions is of utmost importance in the design of functional materials, supramolecular assemblies, pharmaceuticals, and catalysts. Over the past two decades, there has been a significant surge in research and applications on halogen bonds, driven by their exceptional properties such as high directionality and unique tunability when compared to hydrogen bonds. Taking inspiration from nature and other synthetic anion-binding receptors that effectively employ multiple noncovalent interactions in a concerted manner, we have developed an innovative preorganization strategy termed the Hydrogen Bond Enhanced Halogen Bond. This unique combination of hydrogen and halogen bond interactions yields an anion-binding performance over an order of magnitude greater than that achieved with either hydrogen bonds or halogen bonds alone. In-depth investigations, including examinations of solvent effects and substituent impacts, have been undertaken to gain insights into this interaction. We have also pushed the boundaries of this interaction by incorporating non-traditional C-H hydrogen bond donors. This dissertation provides significant insights of this interaction fueling the development of new generations of halogen bond-based anion receptors with exciting applications in anion recognition, organocatalysis, anion transport, and anion sensing. The ensuing chapters provide a comprehensive overview of this study. Chapter 1 introduces halogen bonding, tracing its evolution from hydrogen bonds, elucidating unique traits, and exploring preorganization strategies within the Hydrogen Bond Enhanced Halogen Bond (HBeXB). It also uncovers the captivating realm of anion binding through halogen bonds, highlighting their significance in applications. In Chapter 2, the investigation delves into intriguing solvatochromism and fluorescence responses to anions in halogen bonding anion receptors. Chapter 3 delves into the intricate interplay between hydrogen and halogen bonds, with a focus on quantification of the substituent effects in the hydrogen bond enhanced halogen bond. In Chapter 4, we delve into unconventional approaches to enhance halogen bonds using non-traditional hydrogen bonds, shedding light on anion binding in solution and offering innovative insights into this facet of XB···anion interaction. Finally, Chapter 5 summarizes our findings and offers a glimpse into the future

Distributed Adaptive Huber Regression

Distributed data naturally arise in scenarios involving multiple sources of observations, each stored at a different location. Directly pooling all the data together is often prohibited due to limited bandwidth and storage, or due to privacy protocols. This paper introduces a new robust distributed algorithm for fitting linear regressions when data are subject to heavy-tailed and/or asymmetric errors with finite second moments. The algorithm only communicates gradient information at each iteration and therefore is communication-efficient. Statistically, the resulting estimator achieves the centralized nonasymptotic error bound as if all the data were pooled together and came from a distribution with sub-Gaussian tails. Under a finite $(2+\delta)$-th moment condition, we derive a Berry-Esseen bound for the distributed estimator, based on which we construct robust confidence intervals. Numerical studies further confirm that compared with extant distributed methods, the proposed methods achieve near-optimal accuracy with low variability and better coverage with tighter confidence width.Comment: 29 page

Muti-frequency extended sampling method for the inverse acoustic source problem

We consider the reconstruction of the compact support of an acoustic source given multiple frequency far field data. We propose a multi-frequency extended sampling method (MESM). The MESM computes the solutions of some ill-posed integral equations and constructs an indicator function to image the source. The behavior of the indicator function is justified. The method is fast and easy to implement. Various numerical examples are presented to show the effectiveness of the MESM for both frequency-independent and frequency-dependent sources

Anisotropic nanomechanical properties of bovine horn using modulus mapping

Bovine horns are durable that they can withstand an extreme loading force which with special structures and mechanical properties. In this paper, we apply quasi-static nanoindentation and modulus mapping techniques to research the nanomechanical properties of bovine horn in the transverse direction (TD) and longitudinal direction (LD). In quasi-static nanoindentation, the horn’s modulus and hardness in the inner layer and the outer layer demonstrated a gradual increase in both TD and LD. Laser scanning confocal microscopy (LSCM) revealed microstructure in the horn with wavy morphology in the TD cross-section and laminate in the LD cross-section. When using tensile tests or quasi-static nanoindentation tests alone, the anisotropy of the mechanical properties of bovine horn were not obvious. However, when using modulus mapping, storage modulus (E′), loss modulus (E″) and loss ratio (tan δ) are clearly different depending on the position in the TD and LD. Modulus mapping is proposed as accurately describing the internal structures of bovine horn and helpful in understanding the horn’s energy-absorption, stiffness and strength that resists forces during fighting

Design optimization and wind tunnel investigation of a flapping system based on the flapping wing trajectories of a beetle's hindwings

To design a flapping-wing micro air vehicle (FWMAV), the hovering flight action of a beetle species (Protaetia brevitarsis) was captured, and various parameters, such as the hindwing flapping frequency, flapping amplitude, angle of attack, rotation angle, and stroke plane angle, were obtained. The wing tip trajectories of the hindwings were recorded and analyzed, and the flapping kinematics were assessed. Based on the wing tip trajectory functions, bioinspired wings and a linkage mechanism flapping system were designed. The critical parameters for the aerodynamic characteristics were investigated and optimized by means of wind tunnel tests, and the artificial flapping system with the best wing parameters was compared with the natural beetle. This work provides insight into how natural flyers execute flight by experimentally duplicating beetle hindwing kinematics and paves the way for the future development of beetle-mimicking FWMAVs

Incidence and fatality of serious suicide attempts in a predominantly rural population in Shandong, China: a public health surveillance study

Objectives To estimate the incidence of serious suicide attempts (SSAs, defined as suicide attempts resulting in either death or hospitalisation) and to examine factors associated with fatality among these attempters. Design A surveillance study of incidence and mortality. Linked data from two public health surveillance systems were analysed. Setting Three selected counties in Shandong, China. Participants All residents in the three selected counties. Outcome measures Incidence rate ( per 100 000 person-years) and case fatality rate (%). Methods Records of suicide deaths and hospitalisations that occurred among residents in selected counties during 2009–2011 (5 623 323 person-years) were extracted from electronic databases of the Disease Surveillance Points (DSP) system and the Injury Surveillance System (ISS) and were linked by name, sex, residence and time of suicide attempt. A multiple logistic regression model was developed to examine the factors associated with a higher or lower fatality rate. Results The incidence of SSAs was estimated to be 46 (95% CI 44 to 48) per 100 000 person-years, which was 1.5 times higher in rural versus urban areas, slightly higher among females, and increased with age. Among all SSAs, 51% were hospitalised and survived, 9% were hospitalised but later died and 40% died with no hospitalisation. Most suicide deaths (81%) were not hospitalised and most hospitalised SSAs (85%) survived. The fatality rate was 49% overall, but was significantly higher among attempters living in rural areas, who were male, older, with lower education or with a farming occupation. With regard to the method of suicide, fatality was lowest for non-pesticide poisons (7%) and highest for hanging (97%). Conclusions The incidence of serious suicide attempts is substantially higher in rural areas than in urban areas of China. The risk of death is influenced by the attempter’s sex, age, education level, occupation, method used and season of year

Recent advances of exosomes in age-related macular degeneration

Exosomes are 30–150 nm extracellular vesicles that are secreted by almost all types of cells. Exosomes contain a variety of biologically active substances, such as proteins, nucleic acids, and lipids, and are important in the intercellular communication of biological mediators involved in nerve injury and repair, vascular regeneration, immune response, fibrosis formation, and many other pathophysiological processes. Although it has been extensively studied in the field of cancer, the exploration of ocular diseases has only just begun. Here, we discuss the latest developments in exosomes for age-related macular degeneration (AMD), including the pathogenesis of exosomes in age-related macular degeneration, their potential as diagnostic markers, and therapeutic vectors of the disease. Finally, the study of exosomes in age-related macular degeneration is still relatively few, and more detailed basic research and clinical trials are needed to verify its application in treatment and diagnosis, so as to adopt more personalized diagnosis and treatment strategies to stop the progression of age-related macular degeneration

The Characteristics of the Dominant Flow Channel Using Ma20 Block in the Liaohe Oilfield as an Example

The existence of the dominant flow channel caused the oil field recovery efficiency low, the rising cost of production and the development benefit drop, which brought great pressure to oilfield development, so the study of the characteristics of the dominant flow channel is increasingly urgent. According to the geologic features and the production process of long-term water injection development in the Ma20 block of the Liaohe oilfield, reservoir heterogeneity is the root cause of forming the dominant flow channel. The characteristics of the dominant flow channel in the process of water injection were analyzed. By analyzing the performance characteristics of the dominant flow channel in the dynamic production data, electrical, static and so forth, the dominant flow channel was determined to guide water injection development of oilfield and provide the basis for the research of other dominant flow channel of high water-cut stage reservoir.Key words: The dominant flow channel; Development benefit; Geologic features; Heterogeneity; Development of water injectio