Tele-connection of embodied carbon emissions from industries in China's trade: A complex network analysis.

Regions can meet their development demands through trade, with the attendant environmental costs being shifted to other regions, and carbon emissions emitted from different industries could be transferred over long distances through the increasingly diversified trade network. However, it remains unclear how regional trade leads to the tele-connection and transfer of embodied carbon emissions form industries, and what is the structure and characteristics of the transfer. Thus, multiregional input‒output models and complex network analysis are employed to reveal the tele-connection of carbon emissions from industries in China. The results show that embodied carbon emissions from trade increased by 869.47 million tons during in five years, with North China being the largest outflow area, while the coastal regions being the inflow areas. Moreover, the secondary industry is the highest source of embodied carbon emissions, accounting for 96.68 % of the volume, and the transfer of carbon emissions mainly occurs in North and East China. In carbon emissions networks, North China holds a controlling position, as analysed by degree and strength. The first 23.3%-30% of nodes carry about 62.6%-72.4% of the entire carbon emissions flow, and the network conforms to scale-free features. Centrality further reveals that northern and coastal areas occupy core positions, with interregional carbon flows dominating the critical pathways in the network. The number of clusters evolved from three to four communities during 2012-2017 in the network, demonstrating that the carbon flow network is developing towards multipolarity and modularity. This study underscores the urgency of mitigating carbon emissions in industrial trade by identifying key nodes and cluster structures in emission networks.

The dynamic relationships between landscape structure and ecosystem services: An empirical analysis from the Wuhan metropolitan area, China.

Environmental managers have been striving to optimize landscape structure to achieve a sustained supply of ecosystem services (ESs). However, we still lack a full understanding of the relationships between landscape structure and ESs due to the absence of thorough investigations on the variability of these relationships in space and time. To fill this critical gap, we assessed landscape structure alongside four important ESs (agricultural production (AP), carbon sequestration (CS), soil conservation (SC), and water retention (WR)) in the Wuhan metropolitan area (WMA), and then analyzed the spatiotemporal impacts of landscape structure on ESs from 2000 to 2020 using Geographically and Temporally Weighted Regression. The results show only AP maintained a stable growth trend over the past two decades, while the other ESs fluctuated considerably with a noticeable decline in SC and WR. The importance of landscape structure in influencing ESs varies by time and place, depending on the local landscape composition and configuration. In general, landscape composition has a stronger and less temporally stable impact on ESs compared to configuration. Furthermore, increases in landscape diversity, as measured through Shannon's diversity index, and the percentage of woodlands were found to contribute to the simultaneous benefits of multiple ESs, but in most cases the effects of landscape structure on different ESs were different or even opposite, suggesting that trade-offs are critical in landscape management. The findings highlight the complex response of ESs to dramatically changing landscapes in the WMA and can guide decision-makers in precise spatial arrangement and temporal adjustments to improve current landscape management.

Infrared spectra of carbocations and CH4+ in helium.

Infrared (IR) spectra of several hydrocarbon cations are reported, namely CH3+, CH4+, CH5+, CH5+(CH4) and C2H5+. The spectra were generated from weakly-bound helium-cation complexes formed by electron ionization of helium nanodroplets doped with a neutral hydrocarbon precursor. Spectroscopic transitions were registered by photoexcitation of the complexes coupled with mass spectrometric detection of the bare ions. For CH3+, we provide evidence showing that the helium-bound complexes contain 10-20 helium atoms (on average) and have a rotational temperature of ∼5 K. We show that this technique is well-suited to the study of highly symmetric or fluxional ionic species, as these intrinsic properties are preserved in the helium environment. This is in contrast to conventional tagging methods that use a single atom or molecule, which can change the point group or rigidity of the core ion and therefore the spectral profile. We demonstrate this for the highly fluxional molecular ion CH5+, whose spectrum in the current study matches that of the gas phase ion, whereas the fluxionality is lost when a methane tag is added. Finally, we present the first IR spectrum of methane cation, CH4+. The spectrum of this fundamental organic ion shows CH stretching bands consistent with a non-tetrahedral structure, a consequence of Jahn-Teller distortion.

Easily Processable Thermosets with Outstanding Performance via Smart Twisted Small-Molecule Benzoxazines.

High-performance aromatic polymers have excellent thermal, mechanical, and electrical properties and are lightweight, but it is highly challenging to deliver outstanding performances while still maintaining good processability of the precursors. Here, a new family of small-molecule benzoxazine resins with ortho-maleimide functionality is reported, which strikes an exceptional balance between the processability and performance. The excellent processability is attributed to the twisted molecular configurations of ortho-maleimide-substituted benzoxazines, which prevent intermolecular packing in the resin systems. The new benzoxazines can polymerize through multiple routes, which eliminate the twisted structures and create highly cross-linked polymer networks. The resulting new polymers are found to possess fascinating properties such as a high thermal stability (no Tg can be detected before 400 °C), excellent flame retardancy (a heat release capacity of 42.5 J g-1 K-1 ), and low dielectric constants (2.62-2.30 in the frequency range of 1 Hz to 10 MHz). The combined processability and versatility highlight the potential of smart benzoxazines in the preparation of high-performance thermosets, with important new applications that may span aerospace, transportation, and electronic packaging materials.

IR Spectroscopy of the Cesium Iodide-Water Complex.

There has been much interest in I-(H2O) as a simple model for a hydrated iodide ion. Here we explore how this fundamental ion-solvent interaction is modified by the presence of a counterion, specifically Cs+. This has been achieved by forming the CsI(H2O) complex in superfluid helium nanodroplets and then probing this system using infrared spectroscopy. The complex retains the ionic hydrogen bond between the I- and a water OH group seen in I-(H2O), but the Cs+ ion substantially alters the anion-water interaction through formation of a cyclic Cs+-O-H-I- bonding motif. As with I-(H2O), the OH stretching band derived from the hydrogen-bonded OH group shows substructure, splitting into a clear doublet. However, in contrast to I-(H2O), where a tunneling splitting arising from hydrogen atom exchange plays a role, the doublet we observe is attributed solely to an anharmonic vibrational coupling effect.

Dimers of acetic acid in helium nanodroplets.

The structural arrangement of small carboxylic acid molecules in the liquid phase remains a controversial topic. Some studies indicate a dominance of the cyclic dimer that prevails in the gas phase, whilst other studies favor short fragments of the infinite catemer chains that are found in the crystalline phase. Furthermore, difficulties in preparing and probing size-selected catemer segments have resulted in a lack of benchmark data upon which theoretical models of the condensed phases can be built. To address these issues, we have combined infrared spectroscopy and quantum chemical calculations to explore regions of the intermolecular potential energy surface associated with the formation of metastable dimer isomers. The OH stretching region of the spectrum shows that aggregation of acetic acid molecules inside liquid helium nanodroplets yields two distinct metastable dimers, whilst negligible signal is observed from the cyclic dimer that typically overwhelms this spectral region. We deduce that the most abundant isomer in superfluid helium has one strong O-HO[double bond, length as m-dash]C and one weak C-HO[double bond, length as m-dash]C hydrogen bond. Since this bonding motif is common to the dimeric repeating unit of the catemer, it is of fundamental importance for understanding intermolecular interactions in the condensed phases of small carboxylic acids.

Infrared spectroscopy of a small ion solvated by helium: OH stretching region of HeN-HOCO.

Messenger spectroscopy is a well-established method for recording infrared (IR) spectra of molecular ions. It relies upon the tagging of weakly bound atoms or molecules, known as the "messenger," to the ion of interest. The ideal tag species is helium since it has the weakest possible interaction with any molecular ion and is consequently the least likely to alter the structure and function. However, the attachment of a helium tag is challenging because of the exceptionally cold conditions that are inherently required. In this work, electron ionization of doped liquid helium nanodroplets has been used to create cations tagged with a variable number (N) of helium atoms. Mass-selective ion detection has made it possible to record IR spectra as a function of N, thus revealing the effect on the structure and charge distribution within the ionic core as solvation becomes more extensive. We illustrate this capability for protonated carbon dioxide tagged with up to 14 helium atoms, HeN-HOCO+. The first atom preferentially binds to the proton and results in a substantial redshift of 44 cm-1 for the OH stretching vibration, while the stepwise attachment of additional atoms up to N = 7 causes small and progressive blueshifts, which are attributed to the gradual formation of a ring of helium around the carbon atom. The methodology described herein offers a new route to obtain IR spectra of He-tagged ions and provides an insight into ion-solvent interactions at the molecular level.

Infrared Spectroscopy of Methanol and Methanol/Water Clusters in Helium Nanodroplets: The OH Stretching Region.

Infrared (IR) spectra of methanol clusters in helium nanodroplets are reported in the OH stretching region for the first time. A simple series of intense bands are seen which almost perfectly match previous gas phase studies of these clusters and which are consistent with cyclic structures for the trimer and larger clusters. This finding differs from an earlier report of (CH3OH)n clusters in helium nanodroplets, which focused on the CO stretching region and concluded that while the trimer was cyclic, the tetramer and pentamer adopted branched structures based on a cyclic trimer core. We also present preliminary data for small (CH3OH)n(H2O) clusters, and in particular, we report the first IR spectra for (CH3OH)2(H2O) and (CH3OH)3(H2O). Supporting ab initio calculations suggest that, like the pure methanol clusters, cyclic structures are adopted by these mixed solvent clusters in helium droplets.

Infrared Spectroscopy of NaCl(CH3OH)n Complexes in Helium Nanodroplets.

Infrared (IR) spectra of complexes between NaCl and methanol have been recorded for the first time. These complexes were formed in liquid helium nanodroplets by consecutive pick-up of NaCl and CH3OH molecules. For the smallest NaCl(CH3OH)n, complexes where n = 1-3, the IR data suggest that the lowest-energy isomer is the primary product in each case. The predominant contribution to the binding comes from ionic hydrogen bonds between the OH in each methanol molecule and the chloride ion in the NaCl, as established by the large red shift of the OH stretching bands compared with the isolated CH3OH molecule. For n ≥ 4, there is a dramatic shift from discrete vibrational bands to very broad absorption envelopes, suggesting a profound change in the structural landscape and, in particular, access to multiple low-energy isomers.

Communication: Infrared spectroscopy of salt-water complexes.

To explore how the ion-pair in a single salt molecule evolves with the addition of water, infrared (IR) spectra of complexes composed of NaCl and multiple water molecules have been recorded for the first time. The NaCl(H2O)n complexes were formed and probed in liquid helium nanodroplets, and IR spectra were recorded for n = 1 → 4. The spectra for n = 1, 2, and 3 are consistent with formation of the lowest energy contact-ion pair structures in which each water molecule forms a single ionic hydrogen bond to an intact Na(+)Cl(-) ion-pair. Alternative structures with hydrogen bonding between water molecules become energetically competitive for n = 4, and the IR spectrum indicates likely the coexistence of at least two isomers.

Metastable Aluminum Atoms Floating on the Surface of Helium Nanodroplets.

Metal atoms have proved to be sensitive probes of the properties of superfluid helium nanodroplets. To date, all experiments on the doping of helium droplets have concentrated on the attachment of metal atoms in their ground electronic states. Here we report the first examples of metal atoms in excited states becoming attached to helium nanodroplets. The atoms in question are aluminum, and they have been generated by laser ablation in a metastable quartet state, which attaches to and remains on the surface of helium droplets. Evidence for a surface location comes from electronic spectra, which consist of very narrow absorption profiles that show very small spectral shifts. Supporting ab initio calculations show there to be an energy incentive for a metastable Al atom to remain on the surface of a helium droplet rather than move to the interior. The results suggest that helium droplets may provide a method for the capture and transport of metastable excited atomic and molecular species.

Formation of Au and tetrapyridyl porphyrin complexes in superfluid helium.

Binary clusters containing a large organic molecule and metal atoms have been formed by the co-addition of 5,10,15,20-tetra(4-pyridyl)porphyrin (H2TPyP) molecules and gold atoms to superfluid helium nanodroplets, and the resulting complexes were then investigated by electron impact mass spectrometry. In addition to the parent ion H2TPyP yields fragments mainly from pyrrole, pyridine and methylpyridine ions because of the stability of their ring structures. When Au is co-added to the droplets the mass spectra are dominated by H2TPyP fragment ions with one or more Au atoms attached. We also show that by switching the order in which Au and H2TPyP are added to the helium droplets, different types of H2TPyP-Au complexes are clearly evident from the mass spectra. This study suggests a new route for the control over the growth of metal-organic compounds inside superfluid helium nanodroplets.

Preparation of ultrathin nanowires using superfluid helium droplets.

Direct preparation of long one-dimensional (1D) nanostructures with diameters <10 nm inside superfluid helium droplets is reported. Unlike conventional chemical synthetic techniques, where stabilizers, templates, or external fields are often required to induce 1D growth, here, we exploit the use of quantized vortices to guide the formation of ultrathin nanowires. A variety of elements have been added to the droplets to demonstrate that this is a general phenomenon, including Ni, Cr, Au, and Si. Control of the length and diameter of the nanowires is also demonstrated.

Vortex-induced aggregation in superfluid helium droplets.

The formation of Ag nanoparticles by the addition of Ag atoms to helium droplets has been investigated. The resulting nanoparticles were then imaged by transmission electron microscopy after being deposited on a thin solid surface. In large helium droplets chains of Ag nanorods were observed similar to recently reported track-like deposits [Gomez et al., Phys. Rev. Lett., 2012, 108, 155302]. However, by adjusting the experimental conditions chains of spherical nanoparticles could also be seen with a nearly uniform inter-particle spacing. Given that spherical Ag nanoparticles have no intrinsic anisotropy, the only viable explanation is that these particles must be guided into position by interaction with a quantized vortex spanning the diameter of the helium droplet. Furthermore, addition of Si to the droplets immediately after Ag resulted in Si inserting between the Ag nanoparticles to form continuous nanowires. This eliminates the possibility that the segmented Ag nanostructures are the result of nanowire fragmentation when the helium droplets collide with the deposition substrate. Thus segmented Ag chains are shown to be an intrinsic feature of Ag aggregation in helium droplets in the presence of a quantized vortex.

Helium droplets: a chemistry perspective.

Helium droplets provide an exotic and unique environment for the study of physical and chemical phenomena. Properties of these droplets include a low temperature (0.37 K), their superfluidity, and the ability to easily add a wide variety of atoms and molecules. This tutorial review provides a concise account of the basic principles of helium droplets, including how to form, dope, and interrogate these objects. There then follows a series of selected applications grouped under particular themes, with strong bias towards topics likely to be of particular interest to chemists.

Spindle-like abdominal wall-lifting device in gasless laparoscopic surgery in animal experiments.

INTRODUCTION: CO2 pneumoperitoneum has been used to establish an operation space in laparoscopic surgery. It may have some bad consequences, such as respiratory and circulatory system changes, hypotension and hypoxia in infants and the release of free tumor cells into the abdominal cavity. Gasless laparoscopic technique can avoid these adverse effects. But present gasless laparoscopic techniques have their own disadvantages. The main shortcoming of gasless laparoscopic techniques is inadequate operative space. MATERIAL AND METHODS: We herein describe a new technique. We used a self-designed spindle-like abdominal wall-lifting device to perform gasless laparoscopic cholecystectomy in seven pigs, recording the operation time, bleeding volume and unexpected occurrences during the operation. RESULTS: Seven pigs underwent laparoscopic cholecystectomy using this technique with no conversion to open operation. The operation time was between 21 minutes and 65 minutes, with a mean operative time of 42.5 minutes. The range of bleeding volumes was 2 ml to 8 ml, with a mean operative bleeding volume of 4.3 ml. There were no massive hemorrhages, internal organ injuries or other complications during the operation. CONCLUSIONS: These preliminary outcomes indicate that the spindle-like abdominal wall-lifting device is feasible and safe in gasless laparoscopic cholecystectomy, which can provide sufficient exposure of the operative filed.

Precision engineering of nano-assemblies in superfluid helium by the use of van der Waals forces.

The ability to precisely engineer nanostructures underpins a wide range of applications in areas such as electronics, optics, and biomedical sciences. Here we present a novel approach for the growth of nanoparticle assemblies that leverages the unique properties of superfluid helium. Unlike viscous solvents at or near room temperature, superfluid helium provides an unperturbed and cold environment in which weak van der Waals interactions between molecular templates and metal atoms become significant and can define the spatial arrangement of nanoparticles. To demonstrate this concept, diol and porphyrin-based molecules are employed as templates to grow gold nanoparticle assemblies in superfluid helium droplets. After soft-landing on a solid surface to remove the helium, transmission electron microscopy (TEM) imaging shows the growth of gold nanoparticles at specific binding sites within the molecular templates where the interaction between gold atoms and the molecular template is at its strongest.

Electronic spectroscopy of toluene in helium nanodroplets: evidence for a long-lived excited state.

Optical excitation of toluene to the S1 electronic state in helium nanodroplets is found to alter the rate of production of the fragment ions C7H7(+) and C5H5(+) when the droplets are subjected to subsequent electron ionization. The optical excitation process reduces the abundance of C7H7(+) ions delivered into the gas phase, whereas C5H5(+) ions become more abundant beyond a minimum droplet size. This process contrasts with normal optical depletion spectroscopy, where the optical absorption of a molecular dopant in a helium nanodroplet shrinks the helium droplet, and thus, the electron impact cross-sections because of dissipation of the absorbed energy by evaporative loss of helium atoms. The observations here are interpreted in terms of formation of an excited state in the neutral molecule, which survives for several hundred µs. This long-lived excited state, which is assumed to be the lowest triplet electronic state, shows different cross-sections for production of C7H7(+) and C5H5(+) relative to the S0 state.

Impact of Land-Use Change on Ecosystem Services in the Wuling Mountains from a Transport Development Perspective.

Transportation significantly affects regional land-use changes and ecosystem service functions. Exploring the correlations among transport development, spatial pattern of land-use changes, and ecosystem service changes are important for mitigating the deterioration of regional ecosystems due to human activities. In this study, 2000-2020 was selected as the study period to explore the effects of land-use changes on the ecosystem service value (ESV) in the Wuling Mountains. The results showed that: (1) the Wuling Mountains have experienced four stages of transport development and (2) transportation development has contributed to land-use change. The spatial pattern associated with construction land growth has evolved due to transport development. Garden land has gradually spread into the entire region with transport development. Policies from different periods have had more of an effect on ecological land and cropland. (3) During the study period, the ESV first increased and then declined. The periphery of the transportation axis formed a concentration zone of ESV cold spots. In contrast, ESV hot spots were more concentrated in areas along the Yangtze River. The results of this study provide guidance for land-use policy and spatial planning under the concept of green development.

ATGL promotes colorectal cancer growth by regulating autophagy process and SIRT1 expression.

CRC is a common malignant tumor in the gastrointestinal tract, and its incidence has increased significantly in recent years. Several studies revealed that lipid metabolism reprogramming contributed to tumorigenicity and malignancy by interfering with energy production, membrane formation, and signal transduction in cancers. ATGL is a kind of hydroxy fatty acid ester of fatty acid synthase, and its role in tumor remains controversial. We compared levels of adipose triglyceride lipase (ATGL) in human CRC specimens to adjacent specimens. To validate the effect of ATGL on the proliferation ability of CRC, CCK8 assay and clone formation assay were performed. To evaluate whether autophagy process takes part in the effect of ATGL on CRC proliferation, the value of LC3-II/LC3-I was detected by western blot and we blocked the SIRT1 to detect value of LC3-II/LC3-I and p62 via western blot. In the end, we detected the value of SIRT1 in CRC specimens. We found that ATGL showed high expression in CRC and positively correlated with clinical stage, indicating poor prognosis of CRC. Moreover, ATGL significantly promoted tumor cell proliferation in vitro. Mechanistically, ATGL promoted CRC cells proliferation by blocking mTOR signaling pathway and activating autophagy process. Further, ATGL regulated autophagy process through triggering SIRT1 expression. Our results reveal that ATGL promotes colorectal cancer growth by up regulating autophagy process and SIRT1 expression.