Behavioral dynamics of neuroprotective macrophage polarization in neuropathic pain observed by GHz femtosecond laser two-photon excitation microscopy.

Macrophage polarization in neurotoxic (M1) or neuroprotective (M2) phenotypes is known to play a significant role in neuropathic pain, but its behavioral dynamics and underlying mechanism remain largely unknown. Two-photon excitation microscopy (2PEM) is a promising functional imaging tool for investigating the mechanism of cellular behavior, as using near-infrared excitation wavelengths is less subjected to light scattering. However, the higher-order photobleaching effect in 2PEM can seriously hamper its applications to long-term live-cell studies. Here, we demonstrate a GHz femtosecond (fs) 2PEM that enables hours-long live-cell imaging of macrophage behavior with reduced higher-order photobleaching effect-by leveraging the repetition rate of fs pulses according to the fluorescence lifetime of fluorophores. Using this new functional 2PEM platform, we measure the polarization characteristics of macrophages, especially the long-term cellular behavior in efferocytosis, unveiling the dynamic mechanism of neuroprotective macrophage polarization in neuropathic pain. These efforts can create new opportunities for understanding long-term cellular dynamic behavior in neuropathic pain, as well as other neurobiological problems, and thus dissecting the underlying complex pathogenesis.

The effect of intrinsic strain on the thermal expansion behavior of Janus MoSSe nanotubes: a molecular dynamic simulation.

In this study, we conducted molecular dynamic simulations to investigate the thermal expansion behavior of Janus MoSSe nanotubes. We focused on understanding how the intrinsic strain in these nanotubes affects their thermal expansion coefficient (TEC). Interestingly, we found that Janus MoSSe nanotubes with sulfur (S) on the outer surface (MoSeS) exhibit a different intrinsic strain compared to those with selenium (Se) on the outer surface (MoSSe). In light of this observation, we explored the influence of this intrinsic strain on the TEC of the nanotubes. Our results revealed distinct trends for the TEC along the radial direction (TEC-r) and the axial direction (TEC-lx) of the MoSSe and MoSeS nanotubes. The TEC-rof MoSeS nanotubes was found to be significantly greater than that of MoSSe nanotubes. Moreover, the TEC-lxof MoSeS nanotubes was smaller than that of MoSSe nanotubes. Further analysis showed that the TEC-rof MoSeS nanotubes decreased by up to 37% as the radius increased, while that of MoSSe nanotubes exhibited a slight increase with increasing radius. On the other hand, the TEC-lxof MoSeS nanotubes increased by as much as 45% with increasing radius, whereas that of MoSSe nanotubes decreased gradually. These opposite tendencies of the TECs with respect to the radius were attributed to the presence of intrinsic strain within the nanotubes. The intrinsic strain was found to play a crucial role in inducing thermally induced bending and elliptization of the nanotubes' cross-section. These effects are considered key mechanisms through which intrinsic strain influences the TEC. Overall, our study provides valuable insights into the thermal stability of Janus nanotubes. By understanding the relationship between intrinsic strain and the thermal expansion behavior of nanotubes, we contribute to the broader understanding of these materials and their potential applications.

Opportunities and challenges of post-pandemic's new normal: Rethinking the contribution of the transport sector to China's carbon neutrality by 2060.

As the post-pandemic world adjusts to a new normal, the deep decarbonization of the transport sector, which is essential for China's carbon neutrality, is likely to be faced with unprecedented challenges and opportunities. This study conducted scenario simulations to understand the role of the transport sector in achieving China's carbon neutral target in the context of the post-pandemic new normal. The simulation results showed that carbon dioxide (CO2) emissions could be significantly reduced by lifestyle changes in a post-pandemic world, while the reduction potential would be partially offset by the negative effects stemming from a decline in public transport and car-sharing services. It was also found that the arrival of the post-pandemic new normal could help reduce the mitigation cost required to meet the carbon neutral target. Because of regional disparities in the reduction potential of CO2 emissions and mitigation costs, transport decarbonization toward carbon neutrality requires region-specific policy packages.

Unveiling the complexity of spatiotemporal soliton molecules in real time.

Observing the dynamics of 3D soliton molecules can hold great opportunities for unveiling the mechanism of molecular complexity and other nonlinear problems. In spite of this fantastic potential, real-time visualization of their dynamics occurring on femtosecond-to-picosecond time scales is still challenging, particularly when high-spatiotemporal-resolution and long-term observation are required. In this work, we observe the real-time speckle-resolved spectral-temporal dynamics of 3D soliton molecules for a long time interval using multispeckle spectral-temporal measurement technology. Diverse real-time dynamics of 3D soliton molecules are captured for the first time, including the speckle-resolved birth, spatiotemporal interaction, and internal vibration of 3D soliton molecules. Further studies show that nonlinear spatiotemporal coupling associated with a large average-chirp gradient over the speckled mode profile plays a significant role in these dynamics. These efforts may shed new light on decomposing the complexity of 3D soliton molecules, and create an analogy between 3D soliton molecules and chemical molecules.

Fluorescence visualization of the neuropathic pain triad in trigeminal neuralgia.

Trigeminal neuralgia (TN), an exemplary condition of neuropathic facial pain, seriously affects the physical and mental health of patients, becoming a major medical and social problem. So far, the mechanism of TN and its relation to neuronal activity remain unclear, largely limited by the spatial resolution of visualization methods. In the meanwhile, current therapeutic strategies targeting neurons have not achieved satisfactory outcome. Here, we investigate the neuropathic pain triad in TN by establishing an animal model of TN by chronic constriction injury of the unilateral infraorbital nerve (ION-CCI) and leveraging the single-cell resolution of confocal microscopy, including neuronal hyperexcitability, glial activation, and macrophage polarization. These results can broaden the understanding of TN pathogenesis from neurons to the neuropathic pain triad, and suggest that optical microscopy can provide new opportunities for understanding the complex pathogenesis of TN at single-cell resolution, potentially contributing to the identification of more precise therapeutic targets and the development of more effective treatment modalities.

Four-mode parallel silicon multimode waveguide crossing scheme based on the asymmetric directional couplers.

We theoretically propose and experimentally demonstrate a novel ultra-compact four-mode silicon waveguide crossing device based on the asymmetric directional couplers for densely integrated on-chip mode division multiplexing systems. The crossing is based on the parallel crossing scheme where the two access waveguides are parallel to each other to have minimal area. The device utilizes an idle high order mode inside one bus waveguide to drop subsequently all the guided modes inside another bus waveguide, with the help of the asymmetric directional couplers (ADCs). We also optimize the structural parameters of these ADCs by using the particle swarm optimization method to obtain higher conversion efficiency and smaller coupling length. The simulation results show that the insertion losses of the input 1-8 ports are no more than 0.5 dB at the central wavelength of 1550 nm. And the crosstalks are less than -20 dB in the broadband from 1530 nm to 1580 nm with a footprint of only 25 × 70 µm2. Furthermore, our scheme can be easily extended to accommodate more modes by cascading more ADCs for mode dropping and crossing, without obviously deteriorating the performance and greatly increasing the overall footprint.

Cross-cutting scenarios and strategies for designing decarbonization pathways in the transport sector toward carbon neutrality.

The transport sector will play a pivotal role in achieving China's carbon neutrality goal by 2060. This study develops a regional transport-energy integrated model to analyze the long-term pathways and strategies toward the carbon-neutral ground transport sector in China. A set of scenarios are created to identify the effectiveness and feasibility of low-carbon policy measures based on the well-known transport strategies within the Avoid-Shift-Improve framework. Our simulations shed light on synergistic coupling and trade-offs among different strategies and instruments for prescribing a desirable mix of policy measures that maximize the synergies and minimize the trade-offs. Here, we show that a region-specific policy package designed from a balanced perspective under the Avoid-Shift-Improve framework has the potential to realize a deep decarbonization in the transport sector and will greatly assist in achieving China's carbon neutrality by 2060.

Effect of misfit strain on the thermal expansion coefficient of graphene/MoS2 van der Waals heterostructures.

Because of their advanced properties inherited from their constituent atomic layers, van der Waals heterostructures such as graphene/MoS2 are promising candidates for many optical and electronic applications. However, because heat tends to be generated during the operation of nanodevices, thermal expansion is an important phenomenon to consider for the thermal stability of such heterostructures. In the present work, molecular dynamics simulations are used to investigate the thermal expansion coefficient of the graphene/MoS2 heterostructure, and how the unavoidable misfit strain affects that coefficient is revealed. The misfit strain can tune the thermal expansion coefficient by a factor of six, and this effect is quite robust in the sense that it is insensitive to the size or direction of the heterostructure. Further analysis shows that the misfit strain offers an efficient means of engineering thermally induced ripples, this being the key mechanism for how the misfit strain affects the thermal expansion coefficient. These findings provide valuable information about the thermal stability of van der Waals heterostructures and offer help for practical applications of nanodevices based on such heterostructures.

"What should be computed" for supporting post-pandemic recovery policymaking? A life-oriented perspective.

The COVID-19 pandemic has caused various impacts on people's lives, while changes in people's lives have shown mixed effects on mitigating the spread of the SARS-CoV-2 virus. Understanding how to capture such two-way interactions is crucial, not only to control the pandemic but also to support post-pandemic urban recovery policies. As suggested by the life-oriented approach, the above interactions exist with respect to a variety of life domains, which form a complex behavior system. Through a review of the literature, this paper first points out inconsistent evidence about behavioral factors affecting the spread of COVID-19, and then argues that existing studies on the impacts of COVID-19 on people's lives have ignored behavioral co-changes in multiple life domains. Furthermore, selected uncertain trends of people's lives for the post-pandemic recovery are described. Finally, this paper concludes with a summary about "what should be computed?" in Computational Urban Science with respect to how to catch up with delays in the SDGs caused by the COVID-19 pandemic, how to address digital divides and dilemmas of e-society, how to capture behavioral co-changes during the post-pandemic recovery process, and how to better manage post-pandemic recovery policymaking processes.

Characterization of the spectral memory effect of scattering media.

The optical memory effect is an interesting phenomenon exploited for deep-tissue optical imaging. Besides the widely studied memory effects in the spatial domain to accelerate point scanning speed, the spectral memory effect is also important in multispectral wavefront shaping. Although being theoretically analyzed for decades, quantitative studies of spectral memory effect on a variety of scattering media including biological tissue were rarely reported. In practice, quantifying the range of the spectral memory effect is essential in efficiently shaping broadband light, as it determines the optimum spectral resolution in realizing spatiotemporal focus through scattering media. In this work, we analyze the spectral memory effect based on a diffusion model. An explicit analytical expression involves the illumination wavelength, the diffusion constant, and the sample thickness is derived, which is consistent with the one in the literature. We experimentally quantified the range of spectral correlation for two types of biological tissue, tissue-mimicking phantoms with different concentrations, and diffusers. Specifically, for tissue-mimicking phantoms with calibrated scattering parameters, we show that a correction factor of more than 20 should be inserted, indicating that the range of spectral correlation is much larger than one would expect. This finding is particularly beneficial to multispectral wavefront shaping, as stringent requirements on the spectral resolution could be alleviated by at least one order of magnitude.

Effects of transport-related COVID-19 policy measures: A case study of six developed countries.

This study attempts to provide scientifically-sound evidence for designing more effective COVID-19 policies in the transport and public health sectors by comparing 418 policy measures (244 are transport measures) taken in different months of 2020 in Australia, Canada, Japan, New Zealand, the UK, and the US. The effectiveness of each policy is measured using nine indicators of infections and mobilities corresponding to three periods (i.e., one week, two weeks, and one month) before and after policy implementation. All policy measures are categorized based on the PASS approach (P: prepare-protect-provide; A: avoid-adjust; S: shift-share; S: substitute-stop). First, policy effectiveness is compared between policies, between countries, and over time. Second, a dynamic Bayesian multilevel generalized structural equation model is developed to represent dynamic cause-effect relationships between policymaking, its influencing factors and its consequences, within a unified research framework. Third, major policy measures in the six countries are compared. Finally, findings for policymakers are summarized and extensively discussed.

Imaging biological tissue with high-throughput single-pixel compressive holography.

Single-pixel holography (SPH) is capable of generating holographic images with rich spatial information by employing only a single-pixel detector. Thanks to the relatively low dark-noise production, high sensitivity, large bandwidth, and cheap price of single-pixel detectors in comparison to pixel-array detectors, SPH is becoming an attractive imaging modality at wavelengths where pixel-array detectors are not available or prohibitively expensive. In this work, we develop a high-throughput single-pixel compressive holography with a space-bandwidth-time product (SBP-T) of 41,667 pixels/s, realized by enabling phase stepping naturally in time and abandoning the need for phase-encoded illumination. This holographic system is scalable to provide either a large field of view (~83 mm2) or a high resolution (5.80 µm × 4.31 µm). In particular, high-resolution holographic images of biological tissues are presented, exhibiting rich contrast in both amplitude and phase. This work is an important step towards multi-spectrum imaging using a single-pixel detector in biophotonics.

Effect of misfit strain on the buckling of graphene/MoS2van der Waals heterostructures.

Van der Waals heterostructures inherit many novel electronic and optical properties from their constituent atomic layers. Mechanical stability is key for realizing high-performance nanodevices based on van der Waals heterostructures. However, buckling instability is a critical mechanical issue for heterostructures associated with its two-dimensional nature. Using molecular dynamics simulations of graphene/MoS2heterostructures, we demonstrate the relationship between buckling instability and the misfit strain that arises inevitably in such heterostructures. The impact of misfit strain on buckling depends on its magnitude: (1) A negative misfit strain causes a pre-compression of the graphene layer, which in turn initiates and accelerates buckling in this layer and reduces the buckling stability in the heterostructure as a whole. (2) A small positive misfit strain enhances the buckling stability of the graphene/MoS2heterostructure by pre-stretching and hence decelerating the buckling of the graphene layer (where heterostructure buckling is initiated). (3) In the case of a large positive misfit strain, the graphene layer is pre-stretched while the MoS2layer is significantly pre-compressed, so that heterostructure buckling is initiated by the MoS2layer. Consequently, the buckling stability of the graphene/MoS2heterostructure is reduced by increasing the large positive misfit strain. These findings are valuable for understanding the mechanical properties of van der Waals heterostructures.

Genetic-algorithm-assisted coherent enhancement absorption in scattering media by exploiting transmission and reflection matrices.

The investigations on coherent enhancement absorption (CEA) inside scattering media are critically important in biophotonics. CEA can deliver light to the targeted position, thus enabling deep-tissue optical imaging by improving signal strength and imaging resolution. In this work, we develop a numerical framework that employs the method of finite-difference time-domain. Both the transmission and reflection matrices of scattering media with open boundaries are constructed, allowing the studies on the eigenvalues and eigenchannels. To realize CEA for scattering media with local absorption, we develop a genetic-algorithm-assisted numerical model. By minimizing the total transmittance and reflectance simultaneously, different realizations of CEA are observed and, without setting internal monitors, can be differentiated with cases of light leaked from sides. By modulating the incident wavefront at only one side of the scattering medium, it is shown that for a 5-µm-diameter absorber buried inside a scattering medium of 15 µm × 12 µm, more than half of the incident light can be delivered and absorbed at the target position. The enhancement in absorption is more than four times higher than that with random input. This value can be even higher for smaller absorption regions. We also quantify the effectiveness of the method and show that it is inversely proportional to the openness of the scattering medium. This result is potentially useful for targeted light delivery inside scattering media with local absorption.

Single-shot ultrasound-modulated optical tomography with enhanced speckle contrast.

Ultrasound-modulated optical tomography (UOT) images optical contrast deep inside biological tissue. Among existing approaches, camera-based parallel detection is beneficial in modulation depth but is limited to the relatively slow framerate of cameras. This condition prevents such a scheme from achieving maturity to image live animals with sub-millisecond speckle correlation time. In this work, we developed on-axis single-shot UOT by investigating the statistics of speckles, breaking the restriction imposed by the slow camera framerate. As a proof of concept, we experimentally imaged a one-dimensional absorptive object buried inside a moving scattering medium with speckle correlation time down to 0.48 ms. We envision that this single-shot UOT is promising to cope with live animals with fast speckle decorrelation.

Long-term pathways to deep decarbonization of the transport sector in the post-COVID world.

The novel coronavirus disease 2019 (COVID-19) crisis has influenced economies and societies across the globe and will thoroughly reshape our world as it continues to unfold. The pandemic is likely to trigger permanent long-term impacts on the transport sector in the post-COVID world. While a post-COVID "new normal" will be likely to incur negative consequences, it may provide an opportunity to move toward a more sustainable transport sector. This paper is aimed at developing an urban economic model with an energy focus to depict the dynamics of travel demand, energy consumption, and emissions in the post-COVID world. A set of scenarios was created according to model assumptions regarding lifestyle changes and policy interventions accompanied by the expected post-COVID new normal, to explore long-term pathways toward a deep decarbonization of the transport sector. Scenario simulations demonstrated that working from home, online shopping, and a bike-friendly infrastructure will contribute to a reduction in energy consumption and CO2 emissions, whereas a significant shift from bus to car transport and the decreasing use of car-sharing services will adversely affect CO2 emission reductions. The arrival of the post-COVID world may contribute to an 11% reduction in CO2 emissions by 2060, while the maximum reduction potential could be as high as 44%. Supporting policies and strategies for encouraging remote work and online shopping as well as for promoting safe public transport, active transport, and carpooling services are needed to strongly decarbonize the transport sector in the post-COVID world. Moreover, population distribution and urban structure may also be influenced by the arrival of the post-COVID new normal, which warrant further attention for urban planning.

CGE modeling with disaggregated pollution treatment sectors for assessing China's environmental tax policies.

This research involved constructing a computable general equilibrium (CGE) model for assessing China's latest environmental tax policies. Most environmental CGE models link pollutant emissions to the standard CGE model only by pollution coefficients per unit of sectoral output, and the emission reduction process is not included within production structures. We constructed separate pollution treatment sectors for solid waste management, wastewater management, and waste gas management to describe the pollution treatment processes and identify how policies affect production activities. We compiled the satellite accounts of 18 pollutants from the China Environmentally Extended Input-Output (CEEIO) dataset covering primary gas, water, and solid pollutants and disaggregated the electricity sector into six different production technologies: hydroelectricity, coal power, gas electricity, oil electricity, nuclear power, and renewable energies. We drew two primary conclusions from the simulation results. First, the environmental policies examined could help reduce the emissions of most kinds of pollutants, but also negatively affect GDP. GDP loss by 2030 would be 0.03% in the low environmental tax scenario (LowET), 0.06% in the high environmental tax scenario (HighET), 0.16% in the low environmental tax and low carbon tax scenario (LowETC), and 0.34% in the high environmental tax and high carbon tax scenario (HighETC). SO2 emissions would decrease by 17.4%, 21.0%, 19.3% and 24.5%, respectively, and CO2 emissions would reduce by 0.9%, 1.7%, 5.8% and 11.0%. Second, despite the minor changes in the economic impacts, the effectiveness in pollution treatment of environmental tax policies is underestimated if the pollution treatment sectors are disaggregated in the CGE model. Take the SO2 for an example. The calculated SO2 reductions will increase from 8.95% to 24.46% after disaggregating the pollution treatment sectors in HighETC scenarios.

Tunable thermal expansion coefficient of transition-metal dichalcogenide lateral heterostructures.

The thermal expansion effect plays an important role in governing the thermal stability or the stable configuration of quasi-two-dimensional atomic layers, where the difference between the thermal expansion coefficient of different kinds of atomic layer in lateral heterostructure may cause strong thermal rippling of the atomic layer. We investigate the thermal expansion phenomenon in the WSe2-MoS2 lateral heterostructure. We find that the thermal expansion coefficient can be enhanced by more than a factor of two via varying the ratio between the WSe2 and MoS2 components in the heterostructure. The underlying mechanism is disclosed to be the buckling of the WSe2 region that is induced by the misfit strain at the coherent interface between WSe2 and MoS2. These findings shall be helpful in handling the thermal stability of functional devices based on the transition-metal dichalcogenide lateral heterostructures and other similar quasi-two-dimensional lateral heterostructures.

Landscape ecological security response to land use change in the tidal flat reclamation zone, China.

As coastal development becomes a national strategy in Eastern China, land use and landscape patterns have been affected by reclamation projects. In this study, taking Rudong County, China as a typical area, we analyzed land use change and its landscape ecological security responses in the tidal flat reclamation zone. The results show that land use change in the tidal flat reclamation zone is characterized by the replacement of natural tidal flat with agricultural and construction land, which has also led to a big change in landscape patterns. We built a landscape ecological security evaluation system, which consists of landscape interference degree and landscape fragile degree, and then calculated the landscape ecological security change in the tidal flat reclamation zone from 1990 to 2008 to depict the life cycle in tidal flat reclamation. Landscape ecological security exhibited a W-shaped periodicity, including the juvenile stage, growth stage, and maturation stage. Life-cycle analysis demonstrates that 37 years is required for the land use system to transform from a natural ecosystem to an artificial ecosystem in the tidal flat reclamation zone.