Spatial Isolation Research Articles

Supramolecular Control of Helicene Circularly Polarized Luminescence Emitters in Molecular Solids and Bright Nanoparticles

AbstractCircularly polarized luminescence (CPL) from chiral molecules is attracting much attention due to its potential use in optical materials. However, formulation of CPL emitters as molecular solids typically deteriorates photophysical properties in the aggregated state leading to quenching and unpredictable changes in CPL behavior impeding materials development. To circumvent these shortcomings, a supramolecular approach can be used to isolate cationic dyes in a lattice of cyanostar‐anion complexes that suppress aggregation‐caused quenching and which we hypothesize can preserve the synthetically‐crafted chiroptical properties. Herein, we verify that supramolecular assembly of small‐molecule ionic isolation lattices (SMILES) allows translation of molecular ECD and CPL properties to solids. A series of cationic helicenes that display increasing chiroptical response is investigated. Crystal structures of three different packing motifs all show spatial isolation of dyes by the anion complexes. We observe the photophysical and chiroptical properties of all helicenes are seamlessly translated to water soluble nanoparticles by the SMILES method. Also, a DMQA helicene is used as FRET acceptor in SMILES nanoparticles of intensely absorbing rhodamine antennae to generate an 18‐fold boost in CPL brightness. These features offer promise for reliably accessing bright materials with programmable CPL properties.

How does geographical environment affect residents' perception of social justice: An empirical study from low-income communities in Beijing

With the transition to a market-oriented economic system and the transformation of social structure, urban society has undergone significant spatial differentiation, leading to a deepening divide between the rich and the poor. This has caused issues like social exclusion and spatial isolation to become increasingly prominent, which in turn, limit the harmonious and orderly development of cities. As Beijing's goal to become a “world-class harmonious and livable city” accelerates, there has been a growing focus on ensuring social justice satisfaction for residents in low-income communities. This focus has translated into more attention being paid to spatial equity in residents' living environments. Employing a mixed-methods approach with multi-level regressions to understand the nuanced interplay between urban geography and social equity, where depend variable was subjective questionary from low-income communities in Beijing (2017), the independent variables were geographical factors. Using research data from typical low-income communities in Beijing (2017), our study integrated theories from geography and sociology to examine the spatial equity of the living environment. We then empirically analyzed the impact of geographical environment and objective conditions on residents' perception of social equity in low-income communities. Our findings indicate that there are significant differences in the level of social justice perception among residents across different types of communities. The upscale community with better community environment is not consistent with the evaluation of higher perceived justice. Furthermore, service facilities, employment accessibility, and built environment all influence individual satisfaction with social justice to varying degrees. There is also a moderating effect of living environment satisfaction on social justice perception in low-income communities, with residents' socioeconomic attributes influencing their level of social justice satisfaction. This research contributes to the broader understanding of spatial equity in urban development, highlighting the pivotal role of geographical factors in shaping perceptions of social justice. These insights are crucial for policymakers and urban planners striving for more equitable urban development in rapidly growing cities.

Modulating the electronic structure of Ni and Co in core-shell structured catalysts to enhance the efficiency of reductive amination of pyruvic acid

A core-shell structured catalyst 3Ni-7Co@SiO2-0.2 was created to facilitate the reductive amination of pyruvic acid into alanine and the yield of alanine is up to 99 %. The SiO2 shell played a crucial role in spatial isolation effect, preventing the direct hydrogenation of pyruvic acid and improving the selectivity of alanine. By inter-doping Ni and Co, the electronic structure and properties are adjusted, the d-band center is reduced which is beneficial to the desorption of the product and the reaction barrier is reduced. Furthermore, it is proposed that catalysts exhibit better reductive amination reaction performance when there is a smaller difference in adsorption energy between NH3 and H2 atoms on the metal surface.

Supramolecular Control of Helicene Circularly Polarized Luminescence Emitters in Molecular Solids and Bright Nanoparticles.

Circularly polarized luminescence (CPL) from chiral molecules is attracting much attention due to its potential use in optical materials. However, formulation of CPL emitters as molecular solids typically deteriorates photophysical properties in the aggregated state leading to quenching and unpredictable changes in CPL behavior impeding materials development. To circumvent these shortcomings, a supramolecular approach can be used to isolate cationic dyes in a lattice of cyanostar-anion complexes that suppress aggregation-caused quenching and which we hypothesize can preserve the synthetically-crafted chiroptical properties. Herein, we verify that supramolecular assembly of small-molecule ionic isolation lattices (SMILES) allows translation of molecular ECD and CPL properties to solids. A series of cationic helicenes that display increasing chiroptical response is investigated. Crystal structures of three different packing motifs all show spatial isolation of dyes by the anion complexes. We observe the photophysical and chiroptical properties of all helicenes are seamlessly translated to water soluble nanoparticles by the SMILES method. Also, a DMQA helicene is used as FRET acceptor in SMILES nanoparticles of intensely absorbing rhodamine antennae to generate an 18-fold boost in CPL brightness. These features offer promise for reliably accessing bright materials with programmable CPL properties.

Protected area creation and its limited effect on deforestation: Insights from the Kiziba-Baluba hunting domain (DR Congo)

The study examines the spatiotemporal dynamics of landscape anthropization in the Kiziba-Baluba Hunting Domain (KBHD), near Lubumbashi in southeastern Democratic Republic of Congo, facing increasing human threats. It assesses these dynamics from 1989 to 2023 using remote sensing, Geographic Information Systems (GIS), and landscape ecology principles. The results reveal a significant decrease in forest cover, declining from 70.33 % in 1989 to 26.22 % in 2023, with an annual deforestation rate of -1.84 %. This deforestation has led to the expansion of savannas (63.93 %), agriculture (5.76 %), and built-up and bare soil (0.93 %) through patch creation and aggregation. The level of landscape disturbance has increased sixfold over 34 years, from 0.42 in 1989 to 2.81 in 2023. The reduction in the size of the largest forest patch and increased spatial isolation show rising fragmentation and dissection, often followed by the attrition of residual patches. These findings highlight the inefficiency of current conservation measures in KBHD, indicating a need for restructuring management, redefining protected area boundaries, developing a suitable management plan, implementing reforestation programs, strengthening enforcement of environmental laws, and actively involving local communities.

"Fence" Effect Enabling a Metal-Organic Framework-Derived Single-Atom Co-N-C Catalyst for High-Performance Zn-Air Batteries.

It offers bright prospects to develop non-Pt group metal (non-PGM) electrocatalysts in the area of energy storage and conversion. Herein, we reported a simple spatial isolation strategy to synthesize Co-based electrocatalysts, using partially substituted Zn atoms in a ZnCo-ZIF precursor. The "fence" effect that originated from the partially substituted Zn atoms can yield a better isolation of Co atoms, achieving selective loading of Co species on nitrogen-doped porous carbon varying from nanoparticles to single atoms. The low boiling point of Zn enables abundant porous structures to the N-doped carbon substrate after pyrolysis. The best performing single-atom Co catalyst (Co-SAs/N-C) exhibits excellent oxygen reduction reaction activity in alkaline media. As an illustration, the rechargeable liquid Zn-air battery incorporating the Co-SAs/N-C catalyst demonstrates a substantial open circuit voltage of 1.49 V, a high specific capacity of 689.3 mAh g-1, and remarkable cycling stability over 200 h. This study paves the way for the strategic development of non-PGM electrocatalysts in battery applications.

Towards the Politics of Difference: Mobility and Ethnic Identity in Richard Ford’s Bascombe Novels

Mobility holds profound ethnic, class, and cultural significance in the fiction of the contemporary American writer Richard Ford. Through an analysis of his representative works, including Independence Day, The Lay of the Land and Let Me Be Frank with You, it becomes evident that Ford portrays the “negative mobility” of African Americans under spatial isolation, the transnational mobility of a Chinese immigrant, and the upward social mobility of both groups. In doing so, Ford illuminates disparities in mobility rights, routes, and friction among different ethnic groups, while also revealing shifts in their social status, values, and sense of identity. Furthermore, Ford reflects upon the social reality wherein ethnic minority groups encounter othering and marginalization upon integration into mainstream American society. This exposure lays bare the widespread systemic racial discrimination and deficiencies within the American political and economic system. Additionally, Ford’s depiction of upward social mobility among ethnic minorities underscores the effectiveness of the politics of difference as a means to resist authority and construct ethnic identity. Focusing on the mobility of ethnic minorities deepens our understanding of the survival dilemma and identity crisis faced by them.

Return of the Phrag-i: evaluating sexual reproduction mechanisms amenable to dieback recovery and potential invasiveness across Phragmites australis haplotypes

Phragmites australis is one of the most invasive wetland plants on the planet with both native and invasive haplotypes occurring in the United States. Three Phragmites haplotypes (Delta-, EU- and Gulf-types) co-occur in marshes of the Mississippi River Delta (MRD), where a recent dieback of Phragmites has prompted investigations about the potential for recolonization by seed. In other areas of the US, the invasive EU-type has been shown to spread by seed, yet little is known about reproduction modes of the Delta- and Gulf-types. We conducted a survey at 35 sites along the Mississippi River Delta region in southeast Louisiana to examine the potential for sexual reproduction across haplotypes as well as the potential for hybridization. Seed and pollen samples were collected from Phragmites populations to examine flowering phenology and determine pollen viability of the three lineages. We also conducted a seedbank assay in stands of three haplotypes to test the potential for recruitment by seed. Despite the observed potential for sexual reproduction in Delta- and EU- types, no Phragmites seedlings germinated from the seedbank. EU was the only haplotype to exhibit germination from seeds collected from seed heads. Both spatial separation and temporal isolation in flowering times indicate that hybridization between Phragmites haplotypes in the lower MRD is unlikely. High pollen production, increased pollen production following dieback, and viable seeds in the EU-type suggest that this invasive haplotype has a greater potential to invade new areas and adapt to stressors through sexual reproduction compared to than Delta-or Gulf haplotypes.

Ultra‐Stable and Bright Pure‐Red Perovskite Nanocrystals for Backlit Displays

AbstractMetal halide perovskite nanocrystals (NCs) have emerged as an alternative to conventional phosphors for wide color gamut displays. However, the issues of poor stability and low emission efficiency of pure‐red CsPbBrxI3‐x NCs set an obstacle to their practical application. Herein, the synergistic effect of Mn doping and mesoporous SiO2 sealing is reported through in situ formation of Mn‐doped NCs into mesoporous SiO2 nanospheres (MnNCs@SiO2) to structurally and spatially stabilize the perovskite NCs for bright and stable pure‐red emitter. The large bonding energy of Mn‐halogen effectively suppresses the halide vacancy defects, prompting the highest photoluminescence quantum yield (PLQY) up to 84% (634 nm) among the pure‐red composite analogs. More importantly, the nanocrystal structure stability is fundamentally improved by the enhanced formation energy with Mn doping, together with the spatial isolation by SiO2 nanospheres. The MnNCs@SiO2 films exhibit impressive stabilities against high‐temperature heating, thermal cycle test, UV irradiation, water, and acid/alkali erosion, representing one of the most stable pure‐red perovskite emitters. By integrating fabricated all‐perovskite CsPbX3 single color conversion film into the liquid crystal display (LCD) modules, a wide color gamut of 128% of NTSC is achieved, enabling an excellent color rendition for high‐saturation object colors toward practical applications.

Providing spatial isolation for Mixed-Criticality Systems

Hard real-time systems, characterized by stringent timeliness requirements, occur in an increasing variety of industrial sectors. Some such domains carry important safety-critical concerns, notably avionics, space, and automotive. One common design trend across those domains seeks to reduce the number of computing devices embedded in them by integrating software applications of different criticality levels into one and the same onboard computer. A safety-savvy design approach however requires isolation among components of different criticality, to prevent unintended reciprocal interference across them. Isolation is traditionally achieved through partitioning. Partitioning, however, incurs low resource utilization as cautionary margins are used to inflate partition budgets over their anticipated needs. This situation has prompted research into alternative ways to integration that can safely afford higher levels of utilization. The Mixed-Criticality (MC) approach, which concentrates on the CPU scheduling problem, has yielded a large body of research results that show considerable gains in sustained utilization, but it has yet to meet all of the isolation requirements of safety-critical systems. This work presents a solution to augment a state-of-the-art MC solution with efficient and effective spatial isolation capabilities. Experimental results show that our solution provides adequate guarantees of temporal and spatial isolation with very small runtime overhead.

The impact of geographic isolation and host shifts on population divergence of the rare cicada Subpsaltria yangi

The contributions of divergent selection and spatial isolation to population divergence are among the main focuses of evolutionary biology. Here we employed integrated methods to explore genomic divergence, demographic history and calling-song differentiation in the cicada Subpsaltria yangi, and compared the genotype and calling-song phenotype of different populations occurring in distinct habitats. Our results indicate that this species comprises four main lineages with unique sets of haplotypes and calling-song structure, which are distinctly associated with geographic isolation and habitats. The populations occurring on the Loess Plateau underwent substantial expansion at ∼0.130–0.115 Ma during the Last Interglacial. Geographic distance and host shift between pairs of populations predict genomic divergence, with geographic distance and acoustical signal together explaining > 60% of the divergence among populations. Differences in calling songs could reflect adaptation of populations to novel environments with different host plants, habitats and predators, which may have resulted from neutral divergence at the molecular level followed by natural selection. Geomorphic barriers and climate oscillations associated with Pleistocene glaciation may have been primary factors in shaping the population genetic structure of this species. Ultimately this may couple with a host shift in leading toward allopatric speciation in S. yangi, i.e., isolation by distance. Our findings improve understanding of divergence in allopatry of herbivorous insects, and may inform future studies on the molecular mechanisms underlying the association between genetic/phenotypic changes and adaptation of insects to novel niches and host plants.

Fluorescence-Selective Absorption and Circularly Polarized Fluorescence Energy Transfer Assist the Generation of Multicolor Circularly Polarized Luminescence in Chiral Helical Polyacetylene-Based Janus Nanofibers.

Chiroptical nanomaterials with circularly polarized luminescence (CPL) performance have aroused increasing attention. Herein, multicolor CPL-active Janus nanofibers are prepared through a simple parallel electrospinning method using chiral helical polyacetylenes as the chiral source and achiral fluorophores as the fluorescent source. Interestingly, despite a direct spatial isolation between the chiral component and the fluorescent component, blue and green CPL emissions can still be obtained due to the fluorescence-selective absorption behavior of chiral helical polyacetylenes, with a satisfactory dissymmetric factor (glum) of 2 × 10-2 and 2.5 × 10-3, respectively. Moreover, by taking advantage of the circular polarization fluorescence energy transfer process, red CPL emission is further achieved using the obtained blue and green CPL as energy donors and the achiral red fluorophore as an energy acceptor. The present work offers a facile approach to prepare multilevel-structured chiroptical materials with promising application potentials in a flexible photoelectric device.

Spatial isolation effect improves the acidity and redox capacity of ZSM-5 encapsulating Pt catalyst to achieve efficient toluene oxidation

This paper introduces a novel approach of encapsulating Pt nanoparticles within the pores of a molecular sieve. By comparing the dispersion, reducibility and surface acid sites, the effect of the combination of molecular sieves and Pt particles on the catalytic performance of toluene was studied. The findings demonstrate that Pt nanoparticles were encapsulated within the molecular sieve framework of ZSM-5 molecular sieves using an in-situ synthesis method, exhibiting remarkable catalytic activity towards toluene oxidation (T90=172 ℃). Mainly due to the spatial confinement of the ZSM-5 molecular sieve framework reduces the size of Pt nanoparticles, enhances their dispersion of the Pt@ZSM-5 catalysts. In addition, the space separation effect of ZSM-5 on Pt metal enhances their interaction and promotes the valence state conversion of Pt species. It leads to a large number of acid sites and oxygen vacancies in the catalyst, which improves the adsorption and migration of toluene, thereby improving the catalytic activity. This study will provide valuable insights into the preparation of new nanocatalysts and the catalytic treatment of toluene.

Novel Indium nanocomposites for Photonic applications

In the present communication, MgO:In2O3- 1:1 (MIO), SrO/MgO/In2O3 (1:1:1) (SMIO), SrO/Al2O3/In2O3 (1:1:1) (SAIO) and CeO2/ZnO/In2O3 (1:1:1) (CZIO) NCs are synthesized by Punicagranatum juice extract as a reducing agent followed by calcination at 600 °C for 3 h. The Bragg reflections confirm that Magnesium indate, SrO, Al2O3, ZnO crystallizes in orthorhombic, trigonal, rhombohedral and hexagonal crystalline phases whereas CeO2, In2O3 and MgO crystallizes in cubic phase. Surface morphology consists large number of irregularly sized and shaped nanoparticles along with few pores and hallows. The direct energy band gap was determined using Wood and Tauc’s plot. The direct energy band gap was found to be 3.12, 3.15, 3.18 and 3.05 eV. The optical nonlinearity of the specimens was investigated using the open aperture Z-scan technique. With the exception of SAIO, the synthesized samples exhibited reverse saturable absorption attributed to a two-photon absorption (2PA) process. The nonlinear absorption coefficient follows the order CZIO > MIO > SMIO. However, the optical limiting threshold follows the order SMIO > MIO > CZIO NCs. These findings distinctly highlight the superior potential of CZIO binary NCs for optical limiting applications. This characteristic is advantageous for shielding sensors and the human eye, providing protection against the detrimental effects of intense green laser radiation. Unexpectedly, the SAIO NCs displayed Q-switching behavior. This behavior holds potential applications in optical discriminators, spatial light filters, optical isolation, and other photonic mode-locking devices.

Better Roads, Better Off? Evidence on Upgrading Roads in Tanzania

ABSTRACT Spatial isolation is considered to be one of the main determinants of poverty. Therefore, many transport investments are undertaken with the stated objective of poverty reduction. This paper evaluates the effect of a Tanzanian program that rehabilitated 2,500 km of major roads on rural livelihoods. The analysis uses a large set of variables describing household behavior in order to provide a complete picture of the adjustments. The identification consists of combining a household fixed effects strategy with propensity score matching. Some damaging effects of the program are found on the rural population in the two years following the intervention: the price of rice decreases; households reallocate labor away from agriculture and provide more wage work, but the increase in wage income does not compensate for the loss in agricultural income. Nor do households seem to be benefiting from the fall in the price of rice at consumption level. These results are consistent with rural households facing increased competition due to reduced transportation costs.

Quantitative classification of equipment protection level in concept of zone classification with downtime of protective measures

Handling flammable materials has a risk that can create explosive atmosphere. Such locations are classified as hazardous area, depending on the frequency and volume of explosive atmospheres. General electrical equipment is prohibited in the hazardous area and explosion protected equipment is used. These are the spatial isolation of ignition sources within the fire triangle, but even time isolation can prevent explosion hazards as well. It is proposed a method to classify zones from the calculation of downtime of protective measures based on failure rates and repair times of protective measures related to ventilation in explosive gas atmospheres with the Functional Safety under the time isolation concept. On the other hand, according to International Electrotechnical Commission (IEC) System for Certification to Standards Relating to Equipment for Use in Explosive Atmospheres, explosion protected equipment was also classified as an Equipment Protection Level, "EPL". The EPL should be selected according to the risk of the hazardous area. However, in IEC60079–14:2013, users can choose any EPL according to their risk assessment. In this paper, we clarify the quantitative risk difference of EPLs with expansion the idea of classifying hazardous area from the downtime of protective measures and introduce a means to quantitatively classify the EPL of equipment in an explosive gas atmosphere.

The Alcatraz-Strategy: a roadmap to break the connectivity barrier in malignant brain tumours.

In recent years, the discovery of functional and communicative cellular tumour networks has led to a new understanding of malignant primary brain tumours. In this review, the authors shed light on the diverse nature of cell-to-cell connections in brain tumours and propose an innovative treatment approach to address the detrimental connectivity of these networks. The proposed therapeutic outlook revolves around three main strategies: (a) supramarginal resection removing a substantial portion of the communicating tumour cell front far beyond the gadolinium-enhancing tumour mass, (b) morphological isolation at the single cell level disrupting structural cell-to-cell contacts facilitated by elongated cellular membrane protrusions known as tumour microtubes (TMs), and (c) functional isolation at the single cell level blocking TM-mediated intercellular cytosolic exchange and inhibiting neuronal excitatory input into the malignant network. We draw an analogy between the proposed therapeutic outlook and the Alcatraz Federal Penitentiary, where inmates faced an impassable sea barrier and experienced both spatial and functional isolation within individual cells. Based on current translational efforts and ongoing clinical trials, we propose the Alcatraz-Strategy as a promising framework to tackle the harmful effects of cellular brain tumour networks.

Metal Oxides Derived from Perovskite or Spinel for the Selective Hydrogenation of α,β‐Unsaturated Aldehydes: A Mini–Review

AbstractMixed metal oxides with perovskite ABO3 or spinel AB2O4 structure can provide uniformly and highly dispersed metal oxides, which can be adopted as catalyst supports, as catalysts directly or as catalysts after reduction. When they are used as catalyst supports, the spatial isolation of A‐site ions with B‐site ions not only makes these ions highly dispersed, but also enhances the intimate contact with the active components supported on them, leading to electron transfer or synergistic effect to promote the catalytic ability. After reduction, highly dispersed A/B nanoparticles supported on BOx/AOx can be achieved for the relevant applications. Herein, recent developments in the liquid–phase selective hydrogenation of α,β‐unsaturated aldehydes, with metal oxides derived from perovskite or spinel as supports or catalyst precursors, were summarized.

Environmental filtering governs consistent vertical zonation in sedimentary microbial communities across disconnected mountain lakes.

Subsurface microorganisms make up the majority of Earth's microbial biomass, but ecological processes governing surface communities may not explain community patterns at depth because of burial. Depth constrains dispersal and energy availability, and when combined with geographic isolation across landscapes, may influence community assembly. We sequenced the 16S rRNA gene of bacteria and archaea from 48 sediment cores across 36 lakes in four disconnected mountain ranges in Wyoming, USA and used null models to infer assembly processes across depth, spatial isolation, and varying environments. Although we expected strong dispersal limitations across these isolated settings, community composition was primarily shaped by environmental selection. Communities consistently shifted from domination by organisms that degrade organic matter at the surface to methanogenic, low-energy adapted taxa in deeper zones. Stochastic processes-like dispersal limitation-contributed to differences among lakes, but because these effects weakened with depth, selection processes ultimately governed subsurface microbial biogeography.

Single-Response Duplexing of Electrochemical Label-Free Biosensor from the Same Tag.

Multiplexing is a valuable strategy to boost throughput and improve clinical accuracy. Exploiting the vertical, meshed design of reproducible and low-cost ultra-dense electrochemical chips, the unprecedented single-response multiplexing of typical label-free biosensors is reported. Using a cheap, handheld one-channel workstation and a single redox probe, that is, ferro/ferricyanide, the recognition events taking place on two spatially resolved locations of the same working electrode can be tracked along a single voltammetry scan by collecting the electrochemical signatures of the probe in relation to different quasi-reference electrodes, Au (0V) and Ag/AgCl ink (+0.2V). This spatial isolation prevents crosstalk between the redox tags and interferences over functionalization and binding steps, representing an advantage over the existing non-spatially resolved single-response multiplex strategies. As proof of concept, peptide-tethered immunosensors are demonstrated to provide the duplex detection of COVID-19 antibodies, thereby doubling the throughput while achieving 100% accuracy in serum samples. The approach is envisioned to enable broad applications in high-throughput and multi-analyte platforms, as it can be tailored to other biosensing devices and formats.