Shaanxi Normal University
Recent publications
The application of Microbial Enhanced Oil Recovery relies heavily on the microorganisms in oil wells. However, due to the difficulties in separating bacteria from oil samples, studies on bacterial communities in oil samples are limited. In this study, oil and produced water samples from the same well were collected from the western oilfield of the Ordos Basin, and DNA extraction was effective. Full-length 16S rRNA genes were sequenced using PacBio to study the impact of water flooding on the microbial community structure and the potential biochemical functions of bacteria in a low-permeability reservoir. The results showed that water flooding decreased the temperature and salinity while increasing the dissolved oxygen in the tested oil well. It has influence on the reservoir community. Nitrate-reducing bacteria such as Bradyrhizobium and Methylovirgula are enriched in the reservoir. Nitrate and nitrite can be used as electron acceptors by denitrification to produce N2, which can inhibit the growth of sulfate-reducing bacteria. Additionally, bacteria strains such as Flexistipes and Marinobacter can use hydrocarbons as energy source to degrade crude oil and change its properties. The study demonstrated the presence of a large number of advantageous bacteria in low-permeability reservoirs after water flooding, providing a biological foundation for the application of microbial enhanced oil recovery.
It is a significant and challenging task to detect the informative features to carry out explainable analysis for high dimensional data, especially for those with very small number of samples. Feature selection especially the unsupervised ones are the right way to deal with this challenge and realize the task. Therefore, two unsupervised spectral feature selection algorithms are proposed in this paper. They group features using advanced Self-Tuning spectral clustering algorithm based on local standard deviation, so as to detect the global optimal feature clusters as far as possible. Then two feature ranking techniques, including cosine-similarity-based feature ranking and entropy-based feature ranking, are proposed, so that the representative feature of each cluster can be detected to comprise the feature subset on which the explainable classification system will be built. The effectiveness of the proposed algorithms is tested on high dimensional benchmark omics datasets and compared to peer methods, and the statistical test are conducted to determine whether or not the proposed spectral feature selection algorithms are significantly different from those of the peer methods. The extensive experiments demonstrate the proposed unsupervised spectral feature selection algorithms outperform the peer ones in comparison, especially the one based on cosine similarity feature ranking technique. The statistical test results show that the entropy feature ranking based spectral feature selection algorithm performs best. The detected features demonstrate strong discriminative capabilities in downstream classifiers for omics data, such that the AI system built on them would be reliable and explainable. It is especially significant in building transparent and trustworthy medical diagnostic systems from an interpretable AI perspective.
As a key component of high-powered ultrasonic vibration systems, ultrasonic horns play an important role in various practical application scenarios. Recent advances in longitudinal ultrasonic horns have enabled them to magnify the Langevin transducer's mechanical vibration and efficiently transmit the mechanical vibration to the mechanical load. However, limited research has been devoted to active radial ultrasonic horns in radial vibration. Here we propose an electric impedance-controlled active radial ultrasonic horn (ARUH) capable of tuning both resonance frequency and displacement magnification in radial vibration. The resulting device consists of a radially polarized piezoelectric ring connected with adjustable electric impedance and two metal rings with variable sections. The underlying mechanism is that the change of the converted mechanical impedance of the piezoelectric material by the external electric impedance connected to the piezoelectric material modulates the resonance frequency and displacement magnification of the ARUH. It can be found that the resonant frequency shifts to higher frequencies as the resistance increases and the resonant frequency shifts to lower frequencies as the inductance and capacitance increase, while the displacement magnification has the opposite trend to the resonance frequency. For example, the resonance frequency of the constant-section radial horn is 41130.2 Hz. When the inductance increases from -0.007 to 0.007H, the resonance frequency shifts from 41171.3 to 34606.2 Hz and the displacement magnification moves from 1.189 to 3.5. The experiments are conducted to verify the effectiveness of the resulting device, which is in good agreement with the simulated results and theoretical predictions. Our design with functionality and flexibility opens up possibilities for the design of ARUHs and may find important application prospects in diverse fields such as cold-drawn steel tubes and ultrasonic plastic welding.
Transition metal oxides, especially MnO2 nanoparticles, are often used as cathode of dry batteries and catalysts. They are also promising materials for ultrafast laser applications due to their strong absorption in visible light and near-infrared wavelength range. In this work, high-concentration MnO2 nanoparticles dispersions embedded in the hole cladding of dual-hole photonic crystal fiber is fabricated as a saturable absorber with a modulation depth of 4 % and a saturation intensity of 25 MW/cm². Strong MnO2-light interaction occurs due to enhanced evanescent-field strength (over 10 cm) of the SA could enable stable mode locking operation at 1.55 μm region. By inserting a Sagnac fiber filter in the cavity, multi-state solitons are experimentally demonstrated with identical layout, respectively, which greatly improves the versatility of this laser. This study proves that MnO2 nanoparticles possess excellent nonlinear optical properties in the near-infrared band. The simple in-line structure of the proposed nanoparticles-deposited device could pave a way for high power and all-fiber applications of photonics.
Development of rapid and sensitive method for the discrimination of bases in oligonucleotides is of great importance in clinical diagnosis. Here, we demonstrate the first case of single iridium(III) solvent complex-based electrogenerated chemiluminescence (ECL) and photoluminescence (PL) sensor array for the discrimination of bases in oligonucleotides. One iridium (III) solvent complex ([Ir(ppy)2(DMSO)Cl], ppy = 2-phenylpyridine, probe 1) was designed as both ECL and PL probe while five bases (guanine, adenine, cytosine, thymine and uracil) were chosen as analytes. Two-element sensor array was built for the discrimination of five bases based on the fingerprint response of probe 1 to bases via coordination interactions. The combination of unique ECL and PL variations with principal component analysis was applied for the quantitative analysis of five bases in a linear range of 1.0 μM-10 μM and for the effective discrimination of individual base, the mixture of bases and oligonucleotides. Moreover, the sensor array was successfully applied to discriminate different mismatched ss-DNAs from HIV gene (a fully-matched ss-DNA), even at single-base difference. This work demonstrates that the sensor array using single iridium (III) solvent complex is a promising approach for the discrimination of bases with good sensitivity and simpleness in clinical diagnosis.
Background: Early life adversity (ELA) increases the risk of cardiovascular diseases through dysregulation of cardiovascular stress responses manifested by either exaggerated or blunted reactivity. The catechol-O-methyltransferase (COMT) gene rs4680 polymorphism has been identified in gene-environment interaction (G×E) studies to explain individual differences in the effects of ELA on physiological stress responses. However, little is known about whether ELA interacts with COMT gene rs4680 polymorphism to affect cardiovascular responses to repeated stress exposures. Objective: The current study examined the associations between ELA and cardiovascular responses to repeated stress exposures, and the moderating role of COMT rs4680 polymorphism in these associations. Methods: The childhood trauma questionnaire (CTQ) was administered to 359 junior school students who underwent a two-successive stress exposures protocol with continuous cardiovascular monitoring [heart rate (HR) and systolic and diastolic blood pressure (SBP, DBP)] across four laboratory phases, and their saliva samples for deoxyribonucleic acid (DNA) genotyping were collected. Results: ELA was associated with blunted HR reactivity to the first and second stress exposures, blunted SBP reactivity to the first stress exposure, and attenuated SBP habituation to repeated stress exposures. Moreover, COMT rs4680 moderated these associations, such that the associations between ELA and blunted HR, SBP, and DBP reactivity to the first stress and disrupted DBP habituation to repeated stress exposures only existed in GA/AA genotype carriers but not in GG genotype carriers. Conclusions: These findings suggest that the A allele of COMT rs4680 is vulnerable to the negative effects of ELA on the developmental dysregulation of stress physiological systems.
The n–n heterojunction is formed at the interfaces of FeVO4 and ZnO under hydrothermal conditions to increase the mobility of electrons and to decrease the barrier of oxygen activation. The results from X-ray powder diffraction and X-ray photoelectron spectroscopy analyses confirm the co-existence of the FeVO4 and ZnO phases in the composite. The formation of n–n heterojunction and electron transfer behavior are explored by applying electrochemical techniques and corresponding simulation calculation. The FeVO4/ZnO (Fe:Zn = 1:0.5) sensor shows a high response value of Sg = 42 at 300°C, excellent selectivity, fast response, stable, and superior sensitivity for ethanol detection. The effect of the formed n–n heterojunction on enhancing the gas sensitivity for detecting ethanol is discussed by electron depletion theory. When the gas atmosphere is changed from air to ethanol gas, the depletion layer on the sensor surface is also changed significantly, altering the macroscopic resistance of the material. This work offers a new mechanistic understanding of the role of n–n heterojunction in detecting target gases and paves the way for designing excellent selectivity, fast response, and stable sensors based on n–n heterojunctions.
The aim of this study was to investigate the geographical spatial distribution of creatine kinase isoenzyme (CK-MB) in order to provide a scientific basis for clinical examination. The reference values of CK-MB of 8697 healthy adults in 137 cities in China were collected by reading a large number of literates. Moran index was used to determine the spatial relationship, and 24 factors were selected, which belonged to terrain, climate, and soil indexes. Correlation analysis was conducted between CK-MB and geographical factors to determine significance, and 9 significance factors were extracted. Based on R language to evaluate the degree of multicollinearity of the model, CK-MB Ridge model, Lasso model, and PCA model were established, through calculating the relative error to choose the best model PCA, testing the normality of the predicted values, and choosing the disjunctive kriging interpolation to make the geographical distribution. The results show that CK-MB reference values of healthy adults were generally correlated with latitude, annual sunshine duration, annual mean relative humidity, annual precipitation amount, and annual range of air temperature and significantly correlated with annual mean air temperature, topsoil gravel content, topsoil cation exchange capacity in clay, and topsoil cation exchange capacity in silt. The geospatial distribution map shows that on the whole, it is higher in the north and lower in the south, and gradually increases from the southeast coastal area to the northwest inland area. If the geographical factors are obtained in a location, the CK-MB model can be used to predict the CK-MB of healthy adults in the region, which provides a reference for us to consider regional differences in clinical diagnosis.
  • Ting Nie
    Ting Nie
  • Zhimin Fang
    Zhimin Fang
  • Xiaodong Ren
    Xiaodong Ren
  • [...]
  • Shengzhong Frank Liu
    Shengzhong Frank Liu
Perovskite-based tandem solar cells have attracted increasing interest because of its great potential to surpass the Shockley-Queisser limit set for single-junction solar cells. In the tandem architectures, the wide-bandgap (WBG) perovskites act as the front absorber to offer higher open-circuit voltage (VOC) for reduced thermalization losses. Taking advantage of tunable bandgap of the perovskite materials, the WBG perovskites can be easily obtained by substituting halide iodine with bromine, and substituting organic ions FA and MA with Cs. To date, the most concerned issues for the WBG perovskite solar cells (PSCs) are huge VOC deficit and severe photo-induced phase separation. Reducing VOC loss and improving photostability of the WBG PSCs are crucial for further efficiency breakthrough. Recently, scientists have made great efforts to overcome these key issues with tremendous progresses. In this review, we first summarize the recent progress of WBG perovskites from the aspects of compositions, additives, charge transport layers, interfaces and preparation methods. The key factors affecting efficiency and stability are then carefully discussed, which would provide decent guidance to develop highly efficient and stable WBG PSCs for tandem application.
When an n-partite physical system is measured by n observers, the joint probabilities of outcomes conditioned on the observables chosen by the n- parties form a nonnegative tensor P, called an n-partite correlation tensor (CT). According to the special relativity, CTs can be classified as signaling and nonsignaling ones; and from the point of view of hidden variable theory, CTs can be divided into Bell local and Bell nonlocal ones. In this paper, we aim to establish some Bell bi-inequalities for n-partite Bell local correlation tensors. A Bell bi-inequality consists of two Bell inequalities that hold only for Bell local CTs. First, we obtain an inequality for n-partite nonsignaling CTs, which can be used to check the nonsignaling property of a CT. Second, we recall the mathematical definition of Bell locality of CTs and prove global properties of the set of all Bell local CTs over an index set Δn. Then we establish a series tight Bell bi-inequalities and prove that a CT P is Bell local if and only if it satisfies all tight Bell bi-inequalities. Lastly, we list some examples to illustrate how to establish a Bell bi-inequality.
DNA logic gates have shown outstanding magic in intelligent biology applications, but it remains challenging to construct a portable, affordable and convenient DNA logic gate. Herein, logic gates of gas pressure were innovatively developed for multiplex analysis of metal ions. Hg2+ and Ag+ were input to interact specifically with the respective mismatched base pairs, which activated DNA extension reaction by polymerase and led to the enrichment of platinum nanoparticles for catalyzing the decomposition of peroxide hydrogen. Thus, the gas pressure obtained from a sealed well was used as output for detecting or identifying metal ions. Hg2+ and Ag+ were sensitively and selectively detected, and the assay of the real samples was also satisfactory. Based on this, DNA logic gates, including YES, NOT, AND, OR, NAND, NOR, INHIBIT, and XOR were successfully established using a portable and hand-held gas pressure meter as detector. So, the interactions between DNA and metal ions were intelligently transferred into the output of gas pressure, which made metal ions to be detected portably and identified intelligently. Given the remarkable merits of simplicity, logic operation, and portable output, the metal ion-driven DNA logic gate of gas pressure provides a promising way for intelligent and portable biosensing.
With the ever-changing social environment, individual creativity is facing a severe challenge induced by stress. However, little is known about the physiological mechanisms by which acute stress affects creative cognitive processing. The current study explored the effects of neuroendocrine response on creativity under stress and its underlying cognitive flexibility mechanisms. The Enzyme-Linked Immuno Sorbent Assay was used to assess salivary cortisol, which acted as a marker of stress-induced activation of the hypothalamic-pituitary-adrenal (HPA) axis. Eye blink rate (EBR) and pupil diameter were measured as respective indicators of dopamine and noradrenaline released by activation of the sympathetic-adrenal medullary (SAM) axis. The Wisconsin Card Task (WCST) measured cognitive flexibility, while the Alternative Uses Task (AUT) and the Remote Association Task (RAT) measured separately divergent and convergent thinking in creativity. Results showed higher cortisol increments following acute stress induction in the stress group compared to the control group. Ocular results showed that the stress manipulation significantly increased EBR and pupil diameter compared to controls, reflecting increased SAM activity. Further analysis revealed that stress-released cortisol impaired the originality component of the AUT by increasing perspective errors of the WCST. Serial mediation analyses showed that both EBR and pupil diameter were also associated with increased perspective errors leading to poor originality on the AUT. These findings confirm that physiological arousal under stress can impair divergent thinking through the regulation of different neuroendocrine pathways, in which the deterioration of flexible switching plays an important mediating role.
Lead‐free A3Bi2I9‐type perovskites have been demonstrated as a class of promising semiconductors for high‐performance X‐ray detection due to their high bulk resistivity and strong X‐ray absorption, as well as reduced ion migration. However, due to their long interlamellar distance along their c‐axis, their limited carrier transport along the vertical direction is a bottleneck for their detection sensitivity. Herein, we design a new A‐site cation of aminoguanidinium (AG) with all‐NH2 terminals to shorten the interlayer spacing by forming more and stronger N−H···I hydrogen bonds. The prepared large AG3Bi2I9 single crystals (SCs) render shorter interlamellar distance for a larger mobility‐lifetime product of 7.94 × 10−3 cm2 V−1, which is 3 times higher than the value measured on the best MA3Bi2I9 SC (2.87 × 10−3 cm2 V−1). Therefore, the X‐ray detectors fabricated on the AG3Bi2I9 SC exhibit high sensitivity of 5791 uC Gy−1 cm−2, low detection limit of 2.6 nGy s−1 and short response time of 690 μs, all of which are far better than those of the state‐of‐the‐art MA3Bi2I9 SC detectors. The combination of high sensitivity and high stability enables astonishingly high spatial resolution (8.7 lp mm−1) X‐ray imaging. This work will facilitate the development of low‐cost and high‐performance lead‐free X‐ray detectors. This article is protected by copyright. All rights reserved
Limited Li resources, high cost, and safety risks of using organic electrolytes have stimulated a strong motivation to develop non-Li aqueous batteries. Aqueous Zn-ion storage (ZIS) devices offer low-cost and high-safety solutions. However, their practical applications are at the moment restricted by their short cycle life arising mainly from irreversible electrochemical side reactions and processes at the interfaces. This review sums up the capability of using 2D MXenes to increase the reversibility at the interface, assist the charge transfer process, and thereby improve the performance of ZIS. First, they discuss the ZIS mechanism and irreversibility of typical electrode materials in mild aqueous electrolytes. Then, applications of MXenes in different ZIS components are highlighted, including as electrodes for Zn2+ intercalation, protective layers of Zn anode, hosts for Zn deposition, substrates, and separators. Finally, perspectives are put forward on further optimizing MXenes to improve the ZIS performance.
Excited-state intramolecular proton transfer (ESIPT) has been widely employed for the design of a variety of functionality-led molecular systems. However, precise manipulation of the excited-state reaction is challenging. Herein, we report a new tactic for tuning ESIPT via incorporating an excited-state intramolecular charge transfer (ESICT) process. Specifically, three o-carborane derivatives, NaCBO, PaCBO, and PyCBO, were designed, where the 2-(2'-hydroxyphenyl)-benzothiazole is a typical ESIPT unit functioning as an electron acceptor, and the electron-donating units are naphthyl-(Na), phenanthrenyl-(Pa), and pyrenyl-(Py), respectively. The architectures of the molecules are featured with a face-to-face alignment of the two units. Spectroscopy and theoretical calculation studies revealed that the electron-donating capacity of the donors and solvent polarity continuously modulate the ESIPT/ESICT energetics and dynamics, resulting in distinct emissions. Moreover, the molecules depicted not only highly porous structures but also very different fluorescent colors in the solid state, enabling highly selective film-based fluorescence sensing of mustard gas simulant, 2-chloroethyl ethyl sulfide, with a detection limit of 50 ppb and a response time of 5 s. This work thus provides a reliable strategy for the creation of high-performance sensing fluorophores via ESIPT manipulation.
Photic niche shifts of mammals are associated with changing visual capabilities, primarily mediated by three visual pigments, two (SWS1 and M/LWS) of them for color vision and rhodopsin (RH1) for dim-light vision. To further elucidate molecular mechanisms of mammalian visual adaptations to different light environments, a systematic study incorporating evolutionary analyses across diverse groups and in vitro assays have been carried out. Here, we collected gene sequences for the three opsins from 220 species covering all major mammalian clades. After screening for cone opsin gene losses, we estimated selective pressures on each of the three genes and compared the levels of selection experienced by species living in bright- and dim-light environments. SWS1 pigment is shown to experience accelerated evolution in species living in bright-light environments as has RH1 in aquatic cetaceans, indicating potential shifts for ecological adaptations. To further elucidate the functional mechanisms for these two pigments, we then carried out site-directed mutagenesis in representative taxa. For SWS1, violet and ultraviolet (UV) sensitivity in the pika and mouse are mainly affected by substitutions at the critical sites 86 and 93, which have strong epistatic interaction. For RH1, the phenotypic difference between the sperm whale and bovine sequences is largely contributed by a substitution at site 195, which could be critical for dim-light sensation for deep-diving species. Different evolutionary patterns for the visual pigments have been identified in mammals, which correspond to photic niches, although additional phenotypic assays are still required to fully explain the functional mechanisms.
The concept of spontaneous electric field (Es) in polar structures is crucial for understanding the physical and chemical properties of compound semiconductors and improving their performanes. However, this concept has not been widely accepted so far. Here, we show the first observation of rectification and photovoltaic effects in the polar [0001] direction on the nonpolar ZnO (1010) crystal plane. However, no rectification and photovoltaic effects are observed in the nonpolar [1210] direction perpendicular to the [0001]. When a stress was applied in the [0001] direction of the ZnO single crystal, the rectification and photovoltaic effects are abated and disappeared. The disappearance of the two effects results from the pressure-induced disappearance of the polar structure. The results fully demonstrated that the rectification and photovoltaic effects arise from the existence of Es in the polar [0001] direction. The Es motivates the directional transfer of the electrons and photocreated charges along the [0001] direction, and the rectification and photovoltaic effects are thus observed. These results provide direct evidence for the polar structure theory and suggest that the polar structures can be employed to develop new types of photovoltaic and other electronic and photoelectronic devices.
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2,530 members
Xiangling Zhuang
  • School of Psychology
Feng Kong
  • School of Psychology
Zhong Zhang
  • College of food engineering and nutritional science
Hai-Long Yang
  • College of Mathematics and Informatin Science
Xiaoyang Zhou
  • Management science and engineering management
Xi’an, China