Large Shift Research Articles

Skill-biased technological change and intergenerational education mobility

This paper analyses the impact of skill-biased technological change (SBTC) on intergenerational education mobility. I set up an SBTC model with an overlapping-generations framework, where high and low-income households invest in their children’s skill development. Technology incentivizes these investments by raising the skill-premium and improving life-skills; it constrains investments by increasing inequality. I find that, for SBTC shocks within a critical range, intergenerational investments by both household-types are higher in the new steady-state, with the relative increase being larger for the low-income group. I use cross-U.S. commuting-zone data to examine if education mobility outcomes are better in locations characterized by (1) higher STEM-shares, and (2) larger shifts in the demand of relative skills. I empirically find that children from low-income households are not only more likely to attend college if they live in high-tech areas, but this likelihood increases by a larger margin compared to children from higher-income households.

Simultaneous sensing cyanide and fluoride by Lewis acidic atom regulated–chromophore reaction and applications in real samples

The development of visually fluorescent probes for CN− and F− in one system is challenging. In this paper, a trimethylsilicon-modified pyrrolopyrrole aza-BODIPY (PPAB) conjugate (PPAB-TMSA) was synthesized. By use of Lewis acidic atom regulated–chromophore reaction strategy, PPAB-TMSA was utilized for CN− and F− recognition with high selectivity and low limit of detection (1.3 and 12 nM for CN− and F−, respectively) for the first time. The sensing mechanism revealed that PPAB core was broken by CN− and F− ions through chromophore reaction and trimethylsilicon moiety as an additional F− recognition site could facilely regulate reactivity. As a result, 7.8-fold higher reaction rate of PPAB-TMSA towards CN− than that towards F− and large spectral shift (Δλab = 277 nm, Δλem = 172 nm) led to a distinguishable colometric and fluorescent signals. The practicability was demonstrated by visual detecting F− in toothpaste and CN− in food samples with PPAB-TMSA-loaded test paper. The quantitative detecting endogenous CN− in tapioca flour and bitter almond was successfully demonstrated. This work provides a convenient and visual assay for simultaneous detection CN− and F−, which displays potential applications in real samples.

Optomechanics Driven by Noisy and Narrowband Fields.

We report a study of a cavity optomechanical system driven by narrowband electromagnetic fields, which are applied either in the form of uncorrelated noise, or as a more structured spectrum. The bandwidth of the driving spectra is smaller than the mechanical resonant frequency, and thus we can describe the resulting physics using concepts familiar from regular cavity optomechanics in the resolved-sideband limit. With a blue-detuned noise driving, the noise-induced interaction leads to anti-damping of the mechanical oscillator, and a self-oscillation threshold at an average noise power that is comparable to that of a coherent driving tone. This process can be seen as noise-induced dynamical amplification of mechanical motion. However, when the noise bandwidth is reduced down to the order of the mechanical damping, we discover a large shift of the power threshold of self-oscillation. This is due to the oscillator adiabatically following the instantaneous noise profile. In addition to blue-detuned noise driving, we investigate narrowband driving consisting of two coherent drive tones nearby in frequency. Also in these cases, we observe deviations from a naive optomechanical description relying only on the tones' frequencies and powers.

Size and chemistry of 1–2 layer graphene nanosheets at the transition into photoluminescence and assembly with large shifts from blue to red emission

Synthetic refinement of graphene photoluminescence remains challenging because underlying characteristics have not been well understood from polydisperse mixtures of different sizes and surface chemistries. Here, we isolate and characterise different populations of 1–2 layer graphene (1-2LG) each with narrow size range. Small 1-2LG nanosheets down to 25 nm size remained black and non-luminescent with N. and O. additions at their edges, whereas 15 nm nanosheets transitioned into photoluminescence, while retaining substantial sp2 carbon of graphene. Positively-charged amine modifications overcame the repulsion between nanosheets from the negative zeta potential of sp2 graphene faces in water and allowed assembly of similarly-sized nanosheets with large red shifts (>150 nm) taking blue emission into the red. However, more extensive edge modification into carboxyl groups and neutral amides built negative charge at the edges. Together with smaller nanosheet size and reduced sp2 carbon, red shifts were weakened by half in these isolates, which were most modified and more like graphene oxide and carbon quantum dots. N addition to form amines at nanosheet edges, while avoiding O atom addition and carboxyl groups, presents as a simple refinement for synthesis of self-assembling graphene quantum dots with multi-colour emission, which also retain sp2 carbon properties of graphene.

Red fluorescent AIE bioprobes with a large Stokes shift for droplet-specific imaging and fatty liver diagnosis

Lipid droplets (LDs) as spherical dynamic subcellular organelles, play an important role in various cellular functions such as protein degradation, lipid metabolism, energy storage, signal transduction, and membrane formation. Abnormal function of LDs will lead to a series of diseases and hence monitoring the status of LDs is particularly important. In this study, we synthesized a water-insoluble red fluorescent emitting small molecule fluorescent probe (TPE-TCF), which exhibited aggregation-induced emission (AIE) properties and enabled highly selective real-time imaging of LDs (Pearson’s R value was 0.90). More interestingly, this probe was able to track the dynamic processes of LDs in living cells, including lipophagy, and monitor fatty liver disease in mice. Therefore, TPE-TCF with red fluorescence emission, good biocompatibility, large Stokes shift, AIE properties, LDs imaging, and fatty liver recognition capabilities can be practically used in more LDs-related diseases.

General practitioners' experiences delivering essential care services during the 2020 and 2021 COVID-19-related lockdowns.

The UK provided guidance for general practitioners (GPs) to deliver essential care services during the COVID-19 pandemic. Our objective was to describe local GP experiences and approaches to delivering care while similar formal guidance in Australia was unavailable. Two hundred and ninety-one GPs who practised during the March 2020 to December 2021 COVID-19 lockdowns in Melbourne and Sydney undertook an electronic survey exploring perceptions of essential care service delivery. The provision of care by Australian practices was compared to UK Royal College of General Practitioners' recommendations. Of 274 completed surveys, Australian GP practices were 60% concordant with UK guideline recommendations. There was a large shift towards telehealth service provision across the board, from diagnosis to follow-up. Most care continued if it was deliverable through telehealth or had urgent or time-sensitive need. Local guidance for delivery of essential care services should be developed for future calamities, informed by GPs' experience practising during the COVID 19 pandemic and considering Australian contextual factors.

A naphthimide based fluorescent probe for the detection of thiophenols and its application in actual water and food

Thiophenol (PhSH) and its derivatives are widely employed as common industrial raw materials, while they also pose high toxicity for animals and aquatic organisms. Herein, a novel fluorescent probe P1 was constructed, based on photo-induced electron transfer (PET) mechanism, using naphthimide as the fluorophore and 7-nitrobenzoxadiazole as the recognizing group. Probe P1 exhibited an “Off-On” fluorescence recognition response to PhSH by nucleophilic substitution reaction. The probe displayed advantageous properties for the recognition of PhSH, including a chromogenic response, high selectivity, fast response (< 90 s), and a large Stokes shift (150 nm). In addition, probe P1 exhibited a good linear response to PhSH within the range of 0-9 μM, and the limit of detection (LOD) is 21 nM. Furthermore, probe P1 has been successfully applied for the efficient and rapid PhSH detection in environmental water and actual food samples.

An intramolecular charge transfer based fluorescent probe for imaging of OCl–

The discovery and utilization of new fluorescent chromophore is indispensable to exploit high performance probes for biological research. Stokes shift is one of the most important properties of chromophore accounting for super-resolution fluorescence imaging. Intramolecular charge transfer (ICT) is one of the fundamental mechanisms for fluorescence that accompanied by large Stokes shifts. Based on the conformational changes between ground and excited states, ICT models can be divided into two types: conformation-steady ICT, whose conformation remains unchanged, and conformation-changeable ICT, which is characterized by the rotation of the chromophore around an axis upon excitation. Herein, we report a new chromophore whose donor and acceptor parts took a butterfly geometry with a dihedral angle of 21° in ground state and a planar conformation upon photo excitation. The bent conformation might be ascribed to the extra conjugated double bond, which made the coplanarity of the chromophore in ground state get worse. The chromophore shows a remarkable Stokes shift over 150 nm and a high fluorescence quantum yieldof 0.62. The limit of detection is 41 nM, which enabled the imaging of basal as well as induced OCl– in different cells. Moreover, the pronounced spectroscopic properties ensure the in vivo monitoring of OCl– in arthritic mice. This finding would shed light on the exploitation of small molecule probes based on new fluorescence chromophore for precise biological imaging.

A FRET probe based on flavonol-benzothiazole for the detection of viscosity and SO2 derivatives

Sulfur dioxide (SO2) and viscosity play important roles in living organisms, and abnormal levels of them are associated with many diseases. Hence, a bifunctional fluorescence probe (E)-3-(2-(4-(4-(4-(6-fluoro-3-hydroxy-4-oxo-4H-chromen-2-yl)benzoyl)piperazin-1-yl)styryl)benzo-[d]thiazol-3-ium-3-yl)propane-1-sulfonate (HFBT) with fluorescence resonance energy transfer (FRET) properties was successfully constructed by using 3-hydroxyflavonol as the energy donor and benzothiazole sulphonate derivatives as the energy acceptor, and it can be used for the detection of SO2 derivatives (HSO3−/HSO32−) and viscosity. HFBT exhibits a large Stokes shift (245 nm), high resonance energy transfer efficiency (95.56 %), and excellent selectivity, anti-interference and low limit of detection (LOD = 0.057 μM) for HSO3−. The fluorescence intensity of HFBT at 608 nm gradually increases with the increase of viscosity. Interestingly, a visual HSO3− detection platform was successfully constructed and applied to the quantitative detection of HSO3− in food. Additionally, HFBT was successfully applied to imaging endogenous and exogenous HSO3− in cells. The successful development of HFBT provides an effective tool for the detection and imaging of HSO3− in food and cells.

Development of Donor-acceptor-type Molecules and Their Application as Analytical Reagents

π-Extended donor-acceptor (D-A)-type molecules, which bear both electron-donor and electron-acceptor substituents on the backbone, exhibit unique optical properties, such as bathochromic shifts in absorption and emission, large Stokes shifts, solvatochromic behavior, and fluorescence quenching in polar solvents. These unique properties are attributed to intramolecular charge transfer (ICT) or twisted intramolecular charge transfer (TICT) in the ground and excited states. This review article introduces three types of D-A-type molecules that are used as detection reagents for (1) methanol, (2) amino acids during solid-phase peptide synthesis (SPPS), and (3) amines present in the biological environment. For methanol detection, D-A-type fluorophores with basic guanidine moieties were developed to differentiate between methanol (MeOH) and ethanol (EtOH) based on the small difference in their pKa values (ΔpKa=0.4). Selective protonation of the guanidine moiety in methanol disrupts the D-A structure, allowing emission in the resultant polar environment. Similarly, an acid-base reaction between the hydrogen chloride (HCl) salts of the D-A-type molecules and amines is applied to detect amines during SPPS. In this method, a colorless solution of an HCl salt of the D-A-type molecule is deprotonated by amines, forming a yellow solution. This is the first reported quantitative and non-destructive colorimetric method for detecting amines. Finally, a turn-on-type amine-labeling reagent was developed for the nucleophilic aromatic substitution (SNAr) reaction. This new reagent enables protein staining of living cells with a large Stokes shift and without solvent-polarity-dependent fluorescence quenching.

Fluorescence switching of triarylamine-based polyamides with pendant pyrene units and its application in electrochromic smart displays

The pyrene group was directly connected to the triarylamine (TAA) unit through a benzene bridge via the Suzuki reaction to successfully prepare the diamine monomer. A series of new polyamides (PAs) based on TAA units were prepared by polycondensation. The PAs exhibited good solution processability and high thermal stability with the char yield in excess of 53% at 800°C in air atmosphere. In solvents with different polarities, these PAs showed solvatochromic effect and large stokes shift. Strongly photoluminescent PAs have a sensitive stimulus response to explosive and hazardous gas, and its fluorescence is easily turned off by the addition of trinitrophenol (TNP) and hydrogen chloride (HCl). And achieve fluorescence switching between exposure to HCl and ammonia (NH3) gas. The PAs exhibited a reversible color response in the electrochemical oxidation process, with no significant degradation in current and transmittance after 200 cycles. The sandwich structure multicolor electrochromic device can achieve electrochromic performance applied by different voltages.

Synthesis of low-dimensional metal halide CsAgCl2 for X-ray scintillation applications

Low-dimensional metal halides, which possess efficient luminescent properties, have garnered significant interest in the fields of optoelectronics and radiation detection. This study introduces novel lead-free silver-based metal halide material, CsAgCl2 microcrystals (MCs). These MCs have a one-dimensional atomic chain structure and a unique [AgCl5]4- tetragonal shared triangular configuration. CsAgCl2 MCs exhibit excellent performance as X-ray scintillators due to their bright broadband yellow emission and fast decay time in the microsecond range. The large Stokes shift of 350 nm is produced by self-trapped exciton emission. In X-ray scintillation applications, CsAgCl2 MCs demonstrate a high light yield of 13280 photons/MeV and a wide range of linear scintillation response. It is noteworthy that the CsAgCl2 MCs maintain good stability under both atmospheric conditions and continuous X-ray irradiation. The sample was used in an X-ray imaging screen, which clearly presented the X-ray projection image of a wooden stick. As a result, this research not only contributes to the collection of lead-free metal halide scintillators but also indicates that CsAgCl2 MCs have a wide range of future applications and potential in areas such as medical imaging, scientific research, and diagnostic and detection technologies.

Self–Trapped Exciton versus Band–Edge Electron Transitions: Insights of the Factors Affecting the Optical Properties of Lead–Free Sn–Halide Perovskites

AbstractLead–free Sn–halide perovskites (Sn–HPs) are attractive photomaterials due to their lower toxicity, and some of them with higher stability against moisture and water, compared to their Pb‐based analogous. Interestingly, Sn‐HPs can exhibit two types of optical characteristics: the first scenario is known as band‐edge electron transitions [or band‐to‐band (b‐b) emission], where accumulated electrons in the conduction band recombine with holes in the valence band, providing a close separation between the absorption edge/photoluminescence (PL) peak (small Stokes shift). The second scenario is denominated as self‐trapped exciton (STE), where intraband gap energy states are formed to trap photocarriers generated in the perovskite, producing a broadband PL and a large Stokes shift. These optical features have been suitable for developing prominent devices, but there is no consolidated explanation about the key factors influencing the emergence of b–b emission or STE in Sn‐HPs, mainly the presence of these PL mechanisms in a particular perovskite system. This review highlights how the chemical composition, structural defects, and synthetic procedures are pivotal to producing Sn‐HPs with specific b–b or STE features. This will allow the preparation of Sn‐HPs with better quality/stability, and facile modulation of their PL properties, expanding their future applicability in LCD technologies.

New Lepage-type control charts for joint monitoring of location and scale

This paper introduces two new Shewhart Lepage-type control charts for jointly monitoring the location and scale parameters of continuous processes. The first is based on the van der Waerden (VW) and Ansari-Bradley (AB) tests while the other is on the VW and Mood tests. Statistical performances, in terms of average run length (ARL), of these charts are evaluated numerically and compared with that of their two competitor charts in the existing literature under four distributional models for the process output, namely, the normal, lognormal, Laplace, and logistic. The numerical results show that irrespective of the process distribution, one of the proposed charts (based on VW and Mood tests) has the best performance among all the four charts in the detection of simultaneous shifts in both the parameters of all sizes as well as in the detection of shifts in the scale that have not been accompanied by shifts in the location (only-scale shifts) of all sizes. Moreover, the other proposed chart (based on VW and AB tests) performs better than one of the competitor charts in the existing literature for detecting simultaneous shifts as well as only-scale shifts of all sizes. In addition, it performs better than the other competitor chart for detecting the simultaneous shifts consisting of a large location shift and a small scale shift, however, performs worse than that for detecting the simultaneous shifts consisting of a small location shift and a scale shift of any size, as well as for detecting the only-scale shifts of all sizes. All the four charts perform almost similarly in the detection of only-location shifts of all sizes. Regression models are provided for the proposed charts, which facilitate their designs in practice. Finally, the practical implementation of the proposed charts is illustrated through a real-data example.

A ratiometric fluorescent probe based on phenothiazine and quinazolinone for rapid detection of ClO− and its application

A novel fluorescent probe (BPQ-1) with large conjugated system (phenothiazine was conjugated with quinazolinone) was synthesized. BPQ-1 showed a remarkable ratiometric fluorescence response to ClO− within 10 s, and achieved large stokes shift (168 nm), high sensitivity (LOD = 16.7 nM) and excellent selectivity. Among the analytes to be detected, there is a significant change from bright yellow fluorescence to cyan fluorescence only when ClO− is added to BPQ-1. Through density functional theory calculation and mass spectrometry experiments, the fluorescence response mechanisms of the BPQ-1 are given. In addition, BPQ-1 has been successfully applied to the detection of ClO− in real water samples and test strips for detecting ClO− with different concentrations have been prepared. In particular, the probe has been successfully applied to the fluorescence imaging of exogenous ClO− in living cells.

Exploring Unusual Confined Chemistry: Excited-State Proton Transfer Reaction in Supported Liquid Membrane with Deep Eutectic Solvents.

Supported liquid membrane (SLM) incorporating ionic liquids (ILs) or deep eutectic solvents (DESs) offers a promising method for ion and (bio)chemical separations and CO2 capture. However, a molecular understanding of whether chemical reactions occur in these confined media is crucial. We report excited-state proton transfer (ESPT) reaction of a photoacid, HPTS, in various DES-based SLMs (pore size ∼280 nm) using steady-state and time-resolved fluorescence spectroscopy. Our findings reveal that, while the ESPT is unfavorable in bulk DESs, it occurs substantially in SLM-containing DESs. Time-resolved area normalized emission spectra (TRANES) show that ESPT time ranges from 2.6 to 7.5 ns and is greatly affected by changes in DES constituents. The results suggest that HPTS interacts with ordered DES structures formed by long-range interfacial effects in membrane pores, making it suitable for ESPT. Furthermore, it is found that the dynamics of solvent relaxation in confined DESs are significantly slower than in bulk liquids. This observation, together with a large red-edge excitation shift, supports the impact of long-range interfacial effects on the DES structure inside membrane pores. Given the task-specific properties of DESs, the incorporation of these solvents into SLM pores can be a useful strategy for investigating new chemical processes.

A near-infrared fluorescent probe with a large Stokes shift for the detection and imaging of biothiols in vitro and in vivo.

In this study, a new near-infrared (NIR) fluorescent turn-on probe featuring a large Stokes shift (198nm) was developed for the detection of biothiols. The probe was based on a dicyanoisophorone derivative serving as the fluorophore and a 2,4-dinitrobenzenesulfonyl (DNBS) group functioning as both a recognition site and a fluorescence quencher. In the absence of biothiols, the fluorescence of the probe was low due to the photoinduced electron transfer (PET) effect between the fluorophore and DNBS. Upon the presence of biothiols, the DNBS group underwent a nucleophilic aromatic substitution reaction with the sulfhydryl group of biothiols, leading to the release of the fluorophore and a notable emission peak at 668nm. This developed probe exhibited exceptional selectivity and sensitivity to biothiols in solution, with an impressive detection limit of 28nM for cysteine (Cys), 22nM for homocysteine (Hcy), and 24nM for glutathione (GSH). Furthermore, the probe demonstrated its applicability by successfully visualizing both endogenous and exogenous biothiols in living systems.

A novel fluorescent probe for fast detection of sulfur dioxide derivatives in water, soil, food samples and its applications in biological imaging

Sulfur dioxide (SO2) has a wide range of applications in food additives and industrial production, and it is one of the main substances that form acid rain, causing serious harm to ecosystems and human health. Hence, it is necessary to construct an effective tool to quickly and accurately detect SO2 derivatives in environmental, food, and biological samples. In this study, fluorescent probe NPMQ was built to detect SO2 derivatives from nopinone with the merits of superior water solubility, high sensitivity (12nM), excellent specificity, large Stokes shift (180nm), and rapid response time (within 5s). NPMQ was used to qualitatively and quantitatively detect SO2 derivatives in environmental water, soil and food samples. In addition, an electrospinning film was prepared with the probe NPMQ to image SO2 derivatives, and test strips are capable of rapidly, sensitively, and selectively detecting SO2 derivatives with the naked eye. Moreover, the probe NPMQ was used to visualize endogenous SO2 derivatives in Arabidopsis thaliana under Cd2+ stress. Furthermore, the probe NPMQ was employed to image exogenous and endogenous SO2 derivatives in living Hela, HepG-2 cells, and zebrafish. This study develops an effective tool for monitoring SO2 derivatives in the environmental, food, and biological systems.

Quantum Dot Reporters Designed for CRISPR-Based Detection of Viral Nucleic Acids.

Diagnostic methods based on CRISPR technology have shown great potential due to their highly specific, efficient, and sensitive detection capabilities. Although the majority of the current studies rely on fluorescent dye-quencher reporters, the limitations of fluorescent dyes, such as poor photostability and small Stokes shifts, urgently necessitate the optimization of reporters. In this study, we developed innovative quantum dot (QD) reporters for the CRISPR/Cas systems, which not only leveraged the advantages of high photoluminescence quantum yield and large Stokes shifts of QDs but were also easily synthesized through a simple one-step hydrothermal method. Based on the trans-cleavage characteristics of Cas12a and Cas13a, two types of QD reporters were designed, the short DNA strand and the hybridization-based QD reporters, achieving the detection of DNA and RNA at the pM level, respectively, and validating the performance in the analysis of clinical samples. Furthermore, based on the unique property of QDs that allowed multicolor emission under one excitation, the application potential for simultaneous detection of diseases was further investigated. Taken together, this work proposed novel QD reporters that could be applied to the various CRISPR/Cas systems, providing a new toolbox to expand the diagnosis of bioanalytical and biomedical fields.

Cross-sectional surface analysis of magnetic domains, microstructures, and magnetic properties of the low-temperature phase MnBi prepared by low-temperature vacuum sintering

In this work, the low-temperature phase MnBi prepared by a low-temperature vacuum sintering process at 325 °C was studied. We found a significant increase in the energy product from 2.63 MGOe in the 12-h sintered sample to 3.64 MGOe in the 48-h sintered sample. This improvement is attributed to the solid-liquid diffusion process. Cross-sectional scanning electron microscopy (SEM) reveals that MnBi forms at the external surface of Mn particles and along interior surfaces, notably within cracks. Transmission electron microscopy further demonstrates that the Mn ratio increases and Bi decreases with distance from the crack. The selected area diffraction showed variations in the Mn ratio with distance from cracks and identified both Bi and MnBi phases in the MnBi layer. Magnetic force microscopy (MFM) analysis exhibited large phase shifts indicating repulsive or attractive forces in single ferromagnetic domains. This provides valuable insight into magnetic domains in the MnBi regions near Mn cracks. The MnBi formation model, developed for the vicinity of single cracks with uniform MnBi content, partly explains the magnetic interactions and phase shifts observed near these cracks. These findings provide significant insights into the MnBi microstructural and magnetic properties, potentially useful in tailoring and engineering magnetic structures.