ET Process Research Articles

Color-tunability and energy transfer of a highly thermal-stable BaZnB4O8:Tb3+/Eu3+ phosphor for single-component w-LEDs

A series of Tb3+ single-doped and Tb3+/Eu3+ co-doped BaZnB4O8 samples with color tuning were efficiently synthesized using the solid-state reaction method. The crystal structure, photoluminescence and the energy transfer process (ET) of the samples were systematically studied. The optimal BaZnB4O8:0.08Tb3+ sample shows efficient green emission, then tunable color was achieved by merely introducing a few of Eu3+ ions owing to the highly efficient ET process from Tb3+ to Eu3+ in the BaZnB4O8:0.08Tb3+/yEu3+ samples. The ET efficiency from Tb3+ to Eu3+ of the BaZnB4O8:0.08Tb3+, yEu3+ samples rose from 32.1 % to 51.6 %, simultaneously the luminescent quantum yield improved from 24.7 % to 36.8 %, as the Eu3+ doping concentration increased from 0.125 % to 2 %. Moreover, the Tb3+/Eu3+ co-doped samples exhibited great thermal stability, keeping about 90.2 % (@150 °C) of their original intensity at room temperature. Finally, white light was achieved by a warm w-LEDs fabricated by coating the BaZnB4O8:0.08Tb3+, 0.0025Eu3+ sample on a 365 nm chip. The w-LEDs showed outstanding performance characteristics, with a CCT of 3869 K and a CRI of 89.3. According to the results, Tb3+/Eu3+ co-doped BaZnB4O8 samples have the potential to serve as single-component multicolor-emitting or white-emitting phosphors upon excitation at near-UV wavelength.

CuInS2-Decorated Perovskite Nanoarchitecture: Halide-Driven Energy and Electron Transfer.

Perovskite nanocrystals (NCs) are an emergent and game-changing entrant in semiconductor research, yet the research on the corresponding nanoheterostructures remains in its infancy. In this work, we fabricate a type II nanoarchitecture of CsPbX3 NCs (where X = Cl, Br, or I) and CuInS2 quantum dots to investigate the energy and charge transfer (ET and CT, respectively) processes. Optical measurements of CsPbX3/CuInS2 show efficient photoluminescence (PL) quenching when X = Br or I, while the PL quenching efficiency of the X = Cl compound is 2 orders of magnitude lower. We argue the drastic PL quenching in the X = I compound is solely due to the CT process, while for the X = Br compound, a predominantly ET process is active. In contrast to the driving force (-ΔG) for the CT process, we observe the reverse order of the electron transfer process, for which we propose the electron transfer occurs in the Marcus inverted region. Our halide-dependent controlled regulation of CT and ET processes in these nanoarchitectures may find promising optoelectronic applications.

Proton-induced switching of excitation-wavelength-dependent emission based on mixed-ligand metal–organic frameworks

Switchable Ex-De emission of ML-MOFs has been realized via a proton-controlled ET process, enabling the design of high-level anti-counterfeiting applications.

Automated actual evapotranspiration estimation: Hybrid model of a novel attention based U-Net and metaheuristic optimization algorithms

Actual evapotranspiration (ETa) plays a crucial role in the water and energy cycles of the earth. An accurate estimate of the ETa is essential for management of the water resources, agriculture, and irrigation, as well as research on atmospheric variations. Despite the importance of accurate ETa values, estimating and mapping them remains challenging due to the physical and biological complexity of the ET process. As a novel approach for rapid and reliable estimation of ETa, the present study develops automated deep learning (AutoDL) models that incorporate a metaheuristic optimization algorithm for image processing, architectural design, and hyperparameter tuning. The proposed AutoDL models integrate three different spatial and channel attention mechanisms, including a novel activated spatial attention mechanism (ASPAM), with the U-Net architecture. Bypassing the need for meteorological inputs, the proposed framework uses Moderate Resolution Imaging Spectrometer (MODIS) products and Digital Elevation Model (DEM) data as inputs. To evaluate the performance of the models, they are applied to three study areas in the United States with various climatic characteristics. According to the results, during the spring and summer, when the target values have higher certainty, the estimations are highly promising, with R2 as high as 0.91 and MAPE as low as 6.40%. Furthermore, the proposed ASPAM module improves the accuracy of ETa estimations compared to attention gate (AG) and squeeze and excitation (SE) attention modules. The results also indicate that the MODIS raw products and derived vegetation and water indices can predict ETa within a reliable range of accuracy, with the addition of DEM data marginally enhancing the models' performance. The automatic workflow of this model makes it significantly easy to use, contributing to its applicability and generalizability for enhancing atmospheric research.

Blue-Emissive Nitrogen-Doped Carbon Dots for Picric Acid Detection: Molecular Fluorescence Quenching Mechanism

We report a molecular fluorophore-based concept for the first time, to explain the quenching mechanism of the blue-emissive N-doped carbon dots (NCDs) exhibiting molecular fluorescence (quantum yield = 37%), synthesized through microwave-assisted pyrolysis of malic acid and urea (in 1:3 mole ratio), which has been devised as a fluorescent probe for the sensitive and selective detection of picric acid (PA). A linear Stern–Volmer plot for the fluorescence quenching of NCDs in the PA detection has been observed in the concentration range of 0–1.6 μM, and the limit of detection (LOD) is found to be 33 nM (7.56 ppb). Furthermore, molecular fluorescence in NCDs has been realized to originate from a putative pyridinic (2-pyridone moiety)-type molecular fluorophore, which has been manifested by the inferences drawn from HRMS, 1H NMR, 13C NMR, and XPS studies. The chemical structure of the molecular fluorophore was further validated by correlating the simulated absorption and emission spectra of the molecular fluorophore generated by TD-DFT, with those obtained from NCDs’ experimental data. The underlying photophysical property involved in the simultaneous occurrence of FRET and ET quenching mechanism has been illustrated based on the molecular fluorophore, along with the conventional approach. Here, the role of the molecular fluorophore in the NCDs has been demonstrated as a donor in the ET process involving the NCDs–nitroaromatics pair, where the acid–base interaction between the acceptor (nitroaromatics) and donor has been considered as the essence of the ET process.

Processing and performance of electromagnetic deformation combined with heat treatment of 2195 Al-Li alloy

In this paper, the electromagnetic deformation combined with heat treatment (ET) process was studied, which was meaningful for the forming of high performance Al-Li alloy sheet metal parts. In the ET process, the annealed sheet was firstly subjected to solution treatment, electromagnetic deformation. and artificial age until it reaches the peak aging state. Compared with the traditional T6 heat treatment, the time efficiency of the ET process is significantly improved, and the mechanical properties of the specimen are enhanced. The ET process only takes 6 hours to reach the peak aging, and the time efficiency of precipitate strengthening is reached up to 4 times compared with the T6 process. At the same time, the mechanical properties of the ET specimen are higher than the T6 one, an increase of 17.6% in Vickers hardness. Moreover, the mechanism of higher time efficiency and mechanical properties of the ET process is revealed. It is found that a high density of cellular dislocations and sub-grain were introduced during the electromagnetic deformation process, which is conducive to the nucleation and growth of the T1 precipitate during artificial aging. The T1 precipitates of the ET specimen are more dispersed and finer.

Exciton Transfer at Heterointerfaces of MoS2 Monolayers and Fluorescent Molecular Aggregates.

Integration of distinct materials to form heterostructures enables the proposal of new functional devices based on emergent physical phenomena beyond the properties of the constituent materials. The optical responses and electrical transport characteristics of heterostructures depend on the charge and exciton transfer (CT and ET) at the interfaces, determined by the interfacial energy level alignment. In this work, heterostructures consisting of aggregates of fluorescent molecules (DY1) and 2D semiconductor MoS2 monolayers are fabricated. Photoluminescence spectra of DY1/MoS2 show quenching of the DY1 emission and enhancement of the MoS2 emission, indicating a strong electronic interaction between these two materials. Nanoscopic mappings of the light‐induced contact potential difference changes rule out the CT process at the interface. Using femtosecond transient absorption spectroscopy, the rapid interfacial ET process from DY1 aggregates to MoS2 and a fourfold extension of the exciton lifetime in MoS2 are elucidated. These results suggest that the integration of 2D inorganic semiconductors with fluorescent molecules can provide versatile approaches to engineer the physical characteristics of materials for both fundamental studies and novel optoelectronic device applications.

Assessment of Different Complementary-Relationship-Based Models for Estimating Actual Terrestrial Evapotranspiration in the Frozen Ground Regions of the Qinghai-Tibet Plateau

Actual evapotranspiration (ETa) is important since it is an important link to water, energy, and carbon cycles. Approximately 96% of the Qinghai-Tibet Plateau (QTP) is underlain by frozen ground, however, the ground observations of ETa are particularly sparse–which is especially true in the permafrost regions–leading to great challenge for the accurate estimation of ETa. Due to the impacts of freeze-thaw cycles and permafrost degradation on the regional ET process, it is therefore urgent and important to find a reasonable approach for ETa estimation in the regions. The complementary relationship (CR) approach is a potential method since it needs only routine meteorological variables to estimate ETa. The CR approach, including the modified advection-aridity model by Kahler (K2006), polynomial generalized complementary function by Brutsaert (B2015) and its improved versions by Szilagyi (S2017) and Crago (C2018), and sigmoid generalized complementary function by Han (H2018) in the present study, were assessed against in situ measured ETa at four observation sites in the frozen ground regions. The results indicate that five CR-based models are generally capable of simulating variations in ETa, whether default and calibrated parameter values are employed during the warm season compared with those of the cold season. On a daily basis, the C2018 model performed better than other CR-based models, as indicated by the highest Nash-Sutcliffe efficiency (NSE) and lowest root mean square error (RMSE) values at each site. On a monthly basis, no model uniformly performed best in a specific month. On an annual basis, CR-based models estimating ETa with biases ranging from −94.2 to 28.3 mm year−1, and the H2018 model overall performed best with the smallest bias within 15 mm year−1. Parameter sensitivity analysis demonstrated the relatively small influence of each parameter varying within regular fluctuation magnitude on the accuracy of the corresponding model.

Energy transfer dynamics in thermally stable Sm3+/ Eu3+ co-doped AEAlBS glasses for near UV triggered photonic device applications

Transparent, Sm3+/Eu3+ co-doped alkaline earth alumino borosilicate (AEAlBS) glasses have been synthesized by employing melt quenching process and explored their down-shifting luminescent properties to understand their utility in visible red photonic devices applications. The amorphous (non-crystalline) nature of the as-prepared glasses was analyzed with help of an X-ray powder diffraction (XRD) pattern, containing a broad peak. Photoluminescence (PL) properties demonstrate that the glasses can be proficiently excited by near-UV with a dominant peak centered at 402 nm. The PL emission spectra exhibit four emission peaks with an intense peak placed at 599 nm under 402 nm excitation. The optimum emission intensity was obtained for 0.5 mol% Sm3+ ions doped in AEAlBS glasses. In the present work, Sm3+ ion is acting as an effective sensitizer for Eu3+ activator in AEAlBS glasses, and part of energy gets transferred from sensitizer (Sm3+) to activator (Eu3+) ions. The PL intensity of Eu3+ ions is increasing at the expense of a decrease in the intensity of Eu3+ ion peaks in the co-doping AEAlBS glasses at λex = 402 nm. The efficient ET from sensitizer to activator ions proved to be dipole-dipole in nature via employing Dexter's formula with Reisfeld's approximation. The experimental lifetime values calculated from the PL decay profiles are decreasing with the surge in Eu3+ ion concentration in the as-prepared glasses. Inokuti Hirayama (I-H) model applied to the PL decay profiles confirms the ET process responsible for a decrease in experimental lifetimes as dipole-dipole in nature. The outcome of the I-H model is in consonance with the result given by Dexter theory. The CIE coordinates for single Sm3+ doped glasses are falling in the orange region and gradually surge into the red region by co-doping with Eu3+ ions in AEAlBS glasses. The temperature-dependent emission analysis reveals that the PL intensity at 150 °C and 200 °C perseveres up to 94.34 and 91.30% of the PL intensity at ambient temperature, respectively. All the obtained results contemplate the superiority of the multifunctional Sm3+/Eu3+ co-doped AEAlBS glasses for near UV triggered photonic device applications.

A remote sensing and modeling integrated approach for constructing continuous time series of daily actual evapotranspiration

Satellite remote sensing-based surface energy balance (SEB) techniques have emerged as useful tools for quantifying spatialized actual evapotranspiration at various temporal and spatial scales. However, discontinuous data acquisitions and/or gaps in image acquisition due to cloud cover can limit the applicability of satellite remote sensing (RS) in agriculture water management where continuous time series of daily crop actual evapotranspiration (ETc act) are more valued. The aim of the research is to construct continuous time series of daily ETc act starting from temporal estimates of actual evapotranspiration obtained by SEB modelling (ETa eb) on Landsat-TM images. SEBAL model was integrated with the FAO 56 evaporation model, RS-retrieved vegetative biomass dynamics (by NDVI) and on-field measurements of soil moisture and potential evapotranspiration. The procedure was validated by an eddy covariance tower on a vineyard with partial soil coverage in the south of Sardinia Island, Italy. The integrated modeling approach showed a good reproduction of the time series dynamics of observed ETc act (R2 =0.71, MAE=0.54 mm d-1, RMSE=0.73 mm d-1). A daily and a cumulative monthly temporal analysis showed the importance of integrating parameters that capture changes in the soil-plant-atmosphere (SPA) continuum between Landsat acquisitions. The comparison with daily ETc act obtained by the referenced ET fraction (ETrF) method that considers only weather variability (by ETo) confirmed the lead of the proposed procedure in the spring/early summer periods when vegetation biomass changes and soil water evaporation have a significant weight in the ET process. The applied modelling approach was also robust in constructing the missing ETc act data under scenarios of limited cloud-free Landsat acquisitions. The presented integrated approach has a great potential for the near real time monitoring and scheduling of irrigation practices. Further testing of this approach with diverse dataset and the integration with the soil water modeling is to be analyzed in future work.

Excellent multi-color emission and multi-mode optical ratiometric thermometer in (Ca, Tb, Eu, Sm)Nb2O6 phosphors based on wide O2–→Nb5+ CTB

To meet the demand of ultra-sensitive and high accurate temperature measurements especially in the fields of medical treatment and diagnosis, multi-mode FIR-based optical thermometers as a novel strategy have been developed in recent years. In this work, two types of temperature probes, CaNb2O6 (CNO): Tb3+, Eu3+ and CNO: Tb3+, Sm3+, are firstly designed by high-temperature solid-state method. CNO possesses bright cyan emission excited at 267 nm, wide band gap and good temperature sensing property relative to BaNb2O6 (BNO) and SrNb2O6 (SNO) materials due to sandwich-type structure. Upon 267 nm excitation, Tb3+–Eu3+/Sm3+ doped CNO phosphors achieve multi-color tuning by host → Tb3+→Eu3+/Sm3+ ET channels. Furthermore, the characteristic emission intensity of Tb3+ decrease quickly than that of Eu3+ and Sm3+ due to the competition between thermal quenching and ET process as temperature rising. In the view of different temperature-dependent behaviors, multi-mode FIR (FIR1: ITb1/IEu1/Sm1, FIR2: ITb2/IEu2/Sm2, FIR3: ITb1/IEu2/Sm2 and FIR4: ITb2/IEu1/Sm1) show excellent temperature-sensing performance with the maximum Sa and Sr of 0.036 K−1/ 4.09 % K−1 at high temperature. This work provides a new luminescent material to gain excellent optical thermometer with low cost and high accuracy by multi-mode FIR collaboration.

Radical Mechanism of Ir III /Ni II -Metallaphotoredox-Catalyzed C(sp 3 )–H Functionalization Triggered by Proton-Coupled Electron Transfer: Theoretical Insight

Photoredox catalysis can be induced to activate organic substrates or to modulate the oxidation state of transition-metal catalysts via unique single-electron transfer processes, so as to achieve c...

Electron Injection Process of Porphyrin Dye into a Heterogeneous TiO2/Re(I) Photocatalyst

We now report full details of the collisional ET process at the interface between the solvated porphyrin dye (a representative molecular dye) and heterogeneous TiO2 particles (a well-defined n-type semiconductor), which can be another major electron injection route in dye-sensitized photocatalytic (DSPC) systems based on TiO2 semiconductor besides the typical injection route by oxidative quenching of the TiO2-anchored dye. From temperature-dependent transient profiles of the reductively quenched porphyrin dye (porphyrin•–) with and without TiO2 particles, it was found that there exists a high activation energy (Ea = 57–58 kJ/mol, solvated dye → TiO2 particles) for the collisional electron transfer from the dissolved porphyrin•– to heterogeneous TiO2 semiconductor, which could originate from the low collisional probability between the solution-phase anionic dye and heterogeneous TiO2 particle. This quenching kinetic study provides the first quantitative results showing how the solution-phase dye radical anions transport their photoinduced electrons to the heterogeneous semiconductor side. In addition, the complex photosensitizing behaviors of photo-labile porphyrin dye were investigated with the preparation of the photomodified porphyrin species (ZnPAcet and ZnPEt), which are identified from in situ UV–vis spectroscopy and ESI-mass analysis of the dye solution after photolysis.

Enhancement of Mn4+ Emission by Means of Energy Transfer in Mg2Al4Si5O18:Dy3+, Mn4+ Phosphors

We synthesized a series of Dy3+/Mn4+ doped Mg2Al4Si5O18 phosphors by sintering at 1400 °C. The phase and luminescence properties of the synthesized phosphors were investigated. The XRD results demonstrate that Dy3+ and Mn4+ have successfully entered into the Mg2Al4Si5O18 hosts and occupied crystallographic sites of the hosts. Mg2Al4Si5O18:Mn4+ and Mg2Al4Si5O18:Dy3+ phosphors respectively show emission bands corresponding to 2Eg → 4A2g transitions of Mn4+ and 4F9/2 → 6H15/2, 13/2, 11/2 transitions of Dy3+. For Dy3+ and Mn4+ codoped Mg2Al4Si5O18 phosphors, the emission bands originating from transitions of Dy3+ and Mn4+ are observed. The characteristics of intensity and lifetime of Dy3+ emission suggest Dy3+ → Mn4+ ET process in Dy3+ and Mn4+ codoped Mg2Al4Si5O18 phosphors.

Enhanced luminescence properties of Eu3+ in La2MoO6 by nonsensitization of Bi3+

AbstractIt was unusual for Bi3+ ions to enhance the emission intensity of phosphors via nonsensitization. Here, La2MoO6:Eu3+, Bi3+ phosphors were successfully synthesized by a high temperature solid‐state reaction method in air atmosphere. As the increase of doping concentration of Bi3+, the emission spectra of La2MoO6:Eu3+, Bi3+ phosphors had obvious shifts, splits and the enhancement of intensities, which indicated that the characteristics of the phosphors were modified. To analyze these phenomena, the crystal structure refinements, spectral characteristic analyze and Judd‐Ofelt theoretical calculation were mainly performed. Bi3+ ions played the role of the nonsensitizer and affected the distortion of the crystal, the sites of Eu3+ ions, the field splitting energy and the internal quantum yield. Moreover the nephelauxetic effects of Bi3+ ions and the ET process caused synergistically the life times of La2MoO6:Eu3+, Bi3+ phosphors to increase and then gradually decrease. The CIE coordinates of phosphors changed within a small range. This study might be instrumental in promoting the further application of Bi3+ ions in rare earth luminescent materials.

Frequent and mild scrotal heat stress impairs embryo development, implantation and offspring sex ratio in mice.

Frequent and mild scrotal heat stress (fmSHS) often occurs in humans. The aim of this study was to determine the impact of fmSHS on natural fertility, the IVF-embryo transfer (IVF-ET) process and the offspring sex ratio. Male mice were randomly divided into four groups: no scrotal heat stress (SHS) (controls) and those subjected to SHS at 37°C, 39°C or 41°C for 30min once a week for 5 consecutive weeks. The testis, epididymis and sperm quality were assessed to evaluate the effects of different degrees of SHS, to establish an fmSHS model. Then, natural fertility, IVF-embryo transfer (IVF-ET) results, embryo development, offspring sex ratio and the X/Y chromosome-bearing sperm ratio were examined. SHS at 39°C and 41°C caused mild impairment to spermatozoa, leading to a phenotype similar to oligoasthenozoospermia in humans. Given that most SHS conditions in humans are close to body temperature, SHS of 39°C was adopted to build the fmSHS model. fmSHS reduced the fertilization rate, impaired on-time development and reduced the implantation rate of the embryos in the IVF-ET process, but it did not affect the development or function of blastocysts. The fmSHS mice produced more Y chromosome-bearing spermatozoa and propagated more male offspring. fmSHS not only reduced the fertilization ability of spermatozoa but also influenced their function beyond fertilization, in addition to changing the offspring sex ratio. These results may help to shed new light on the infertility treatment of males with scrotal heat risk and the health concerns of offspring propagated from these fathers.

(Invited) Fructose Biosensors Based on Direct Electron Transfer between Fructose Dehydrogenase and Electrodes

Fructose dehydrogenase (FDH, EC 1.1.99.11) is a bacterial membrane bound flavocytochrome oxidoreductase, which has been widely employed to develop direct electron transfer (DET) and mediated electron transfer (MET) based electrode platforms [1]. Most commonly FDH from Gluconobacter japonicus has been studied. FDH is a heterotrimer consisting of a catalytic dehydrogenase domain, DHFDH (subunit I), where D-(−)-fructose oxidation occurs at the covalently flavin cofactor (FAD), followed by an internal electron transfer (IET) to the cytochrome domain (CYTFDH, subunit II), which contains three heme c moieties coordinated by the enzyme scaffold, and a subunit III, which is not involved in the ET process. We have recently investigated [2-4] how to optimize orientation and the DET reaction between FDH and electrodes. In [2] we report on the influence of pH and monovalent/divalent cations on the catalytic current response, the IET, and the structure of FDH by using amperometry, spectrophotometry, and circular dichroism. Amperometric measurements were performed on graphite electrodes, onto which FDH was adsorbed and the effect on the response current to fructose was investigated when varying the pH and the concentrations of divalent/monovalent cations. In the presence of 10 mM CaCl2, a current increase of up to ≈ 240% was observed, probably due to an intra-complexation reaction between Ca2+ and the aspartate/glutamate residues found at the interface between the DHFDH and CYTFDH. In [3] we present a new method to electrodeposit highly mesoporous gold onto a polycrystalline solid gold electrode without any template. The electrodeposition is carried out by first cycling the electrode potential between +0.8 and 0 V in 10 mM HAuCl4 with 2.5 M NH4Cl and then applying a negative potential for the production of H2 bubbles at the electrode surface. This mesoporous gold electrode was modified with 4-mercaptophenol onto which FDH was orientated to optimize the DET reaction. In [4] an efficient DET reaction was also achieved between FDH and anthracene-modified single-walled carbon nanotubes (SWCNT) deposited onto a glassy-carbon electrode. The SWCNTs were activated in situ with a diazonium salt synthesized through the reaction of 2-aminoanthracene with NaNO2 in 0.5 M HCl for 5 min at 0° C. After the in situ reaction, the 2-aminoanthracene diazonium salt was electrodeposited by running cyclic voltammograms from +1000 to −1000 mV. The anthracene-SWCNT-modified GCE was further incubated in an FDH solution to allow FDH to adsorb. Cyclic voltammograms of the FDH-modified electrode revealed two couples of redox waves ascribed to the heme c 1 and heme c 3 of the CYTFDH. In the presence of 10 mM fructose two catalytic waves could clearly be seen and were correlated with two heme c:s, with a maximum current density of 485±21 μA cm − 2 at 0.4 V at a sweep rate of 10 mV s − 1.

Transition from stochastic events to deterministic ensemble average in electron transfer reactions revealed by single-molecule conductance measurement

Electron transfer reactions can now be followed at the single-molecule level, but the connection between the microscopic and macroscopic data remains to be understood. By monitoring the conductance of a single molecule, we show that the individual electron transfer reaction events are stochastic and manifested as large conductance fluctuations. The fluctuation probability follows first-order kinetics with potential dependent rate constants described by the Butler-Volmer relation. Ensemble averaging of many individual reaction events leads to a deterministic dependence of the conductance on the external electrochemical potential that follows the Nernst equation. This study discloses a systematic transition from stochastic kinetics of individual reaction events to deterministic thermodynamics of ensemble averages and provides insights into electron transfer processes of small systems, consisting of a single molecule or a small number of molecules.

“Express transitioning” as a special case of the demographic transition

The theory of the “(first) demographic transition” (DT) still has considerable practical relevance in the field of population research. For instance, the DT serves as a conceptual model that underlies the UN’s population projections, and is central to the discussion around the so-called “demographic dividend”. Although it was first described 90 years ago, several questions related to the DT remain open or need verification. In particular, there is debate about the question of what the indispensable triggers of the DT are. Assumptions regarding the primary causes include increased education for women and related changes in values, as well as economic development, urbanisation, migration, and the democratisation process. This paper aims to contribute to DT-related research using an innovative research approach. Our study covers all 102 countries with populations that have undergone the DT between 1950 and 2010. Among these countries, we identified 25 populations that passed through this process at an exceptionally high tempo. We refer to this process as “express transitioning” (ET), and seek to identify its main determinants by comparing the ET populations with the populations of the other DT countries. The data we use are taken from theWittgenstein Centre Data Explorer, the UN World Population Prospects, the UN World Urbanization Prospects, the World Bank Group, and the Center for Systematic Peace. Our analysis is based on rather descriptive methods, including ANOVA tests and bivariate correlations.We find that the urbanisation level and the education dynamics are most closely associated with ET, whereas other variables show no significant association with the ET process.

Unraveling Competitive Electron and Energy-Transfer Events at the Interfaces of a 2D MOF and Nile Red Composites: Effect of the Length and Structure of the Linker.

The distribution and interactions of organic molecules adsorbed on the surface of materials play important roles in many catalytic and photonic processes. Here, we show that the length and chemical structure of the linker in new Al-ITQ metal-organic frameworks (MOFs) are fundamental for the dynamics of the dye Nile Red (NR) adsorbed on its surface. For the studied composites using Al-ITQ-4-ethylbenzoic acid (EB), Al-ITQ-4-aminobenzoic acid (AB), and Al-ITQ-EB exposed to the aniline (AN) or N, N-dimethylaniline (DMA) atmospheres, we observed a very fast (∼1.2 ps) intramolecular charge-transfer reaction in adsorbed NR molecules. For NR@Al-ITQ-EB, where the linker has a shorter aliphatic chain (two carbons), the dye molecules present a homoenergy-transfer (ET) process, which is faster (∼90 ps) than in the previously reported NR@Al-ITQ-4-heptylbenzoic acid composite with longer aliphatic chain (seven carbons, ∼220 ps). The more polar environment created by the Al-oxide nodes in Al-ITQ-EB surface around the NR populations strongly favors the ET event. When the linker structure contains phenyl amine moieties, the resulting NR@Al-ITQ-AB composites show different and rich photodynamics, in which a fast electron transfer reaction from the MOF aniline moiety to the adsorbed NR occurs in ∼17 ps, inhibiting the ET process between the dye molecules near the MOF surface. This process also was confirmed in Al-ITQ-EB MOF exposed to AN and DMA gas atmospheres, as well as NR in pure aniline. The obtained results demonstrate how modifications in the length and structure of the organic linker in this MOF change the interface interactions and outcome of the photoinduced processes in the composites. Our findings on dye-MOF interface photobehavior are relevant to the design of new materials in which the interface plays a key role in their performance in the fields of catalysis and photonics.