Molecular Counterparts Research Articles

FEEDBACK from the NGC 7538 H II region

Context. The interaction of expanding H II regions with their environmental clouds is one of the central questions driving the Stratospheric Observatory for Infrared Astronomy (SOFIA) legacy program FEEDBACK. Aims. We want to understand the interaction of the prototypical NGC 7538 H II region with the neighboring molecular cloud hosting several active star-forming regions. Methods. Using the SOFIA, we mapped an area of ~210′2 (~125 pc2) around NGC 7538 in the velocity-resolved ionized carbon fine-structure line [CII] at 1.9 THz (158 μm). Complementary observed atomic carbon [CI] at 492 GHz and high-J CO(8–7) data, as well as archival near- and far-infrared, cm continuum, CO(3–2), and HI data are folded into the analysis. Results. The ionized carbon [CII] data reveal rich morphological and kinematic structures. While the overall morphology follows the general ionized gas that is also visible in the radio continuum emission, the channel maps show multiple bubble-like structures with sizes on the order of ~80–100″ (~1.0–1.28 pc). While at least one of them may be an individual feedback bubble driven by the main exciting sources of the NGC 7538 H II region (the O3 and O9 stars IRS6 and IRS5), the other bubble-like morphologies may also be due to the intrinsically porous structure of the H II region. An analysis of the expansion velocities around 10 km s−1 indicates that thermal expansion is not sufficient but that wind-driving from the central O-stars is required. The region exhibits a general velocity gradient across, but we also identify several individual velocity components. The most blue-shifted [CII] component has barely any molecular or atomic counterparts. At the interface to the molecular cloud, we find a typical photon-dominated region (PDR) with a bar-shape. Ionized C+, atomic C0 and molecular carbon CO show a layered structure in this PDR. The carbon in the PDR is dominated by its ionized C+ form with atomic C0 and molecular CO masses of ~0.45 ± 0.1 M⊙ and ~1.2 ± 0.1 M⊙, respectively, compared to the ionized carbon C+ in the range of 3.6−9.7 M⊙. This bar-shaped PDR exhibits a velocity-gradient across, indicating motions along the line of sight toward the observer. Conclusions. Even if it is shown to be dominated by two nearby exciting sources (IRS6 and IRS5), the NGC 7538 H II region exhibits a diverse set of substructures that interact with each other as well as with the adjacent cloud. Compared to other recent [CII] observations of H II regions (e.g., Orion Veil, RCW120, RCW49), the bubble-shape morphologies revealed in [CII] emission that are indicative of expanding shells are recurring structures of PDRs.

Nanoformulation Safety versus Toxicity; What do the Recent Studies Tell Us?

Nanoparticles (NPs) are a group of substances with characteristics that differ from their bulk and molecular counterparts. Different NPs have various size averages from 1 to 100 nanometers in two or three dimensions. NPs have been used for numerous industrial and domestic purposes, progressively increasing their production. Because of using NPs in different and multiple products, their presence in the environment around us has increased, raising the risk of potentially adverse effects of NPs in

Highly Effective Crosslinker for Redox-Sensitive Gene Carriers

Polyethyleneimine (PEI) has been extensively used as a common gene carrier due to its high gene transfection efficiency. PEI1.8k shows significantly lower cytotoxicity than its high molecular weight counterparts. However, it also has the problem of low gene transfection efficiency. To address the dilemma, a highly effective crosslinker (DTME) was synthesized to react with PEI1.8k to obtain CS-PEI1.8k. The reaction showed several advantages, such as a fast process in room temperature within nine hours with the product which can directly complex with DNA after removing the solvent. The ability of CS-PEI1.8k to agglomerate with DNA was proven by particle size, zeta potential, and gel retardation assays. The cytotoxic in vitro transfection ability and cell internalization capacity of CS-PEI1.8k were tested to verify the transfection capacity of CS-PEI1.8k. Moreover, we also studied the mechanism of the relatively high level of gene transfection by this binary complex compared with PEI25k.

Vibrational spectroscopy analysis of silica and silicate glass networks

AbstractVibrational spectroscopy has been widely used to investigate various structural aspects of the glass network, and there are a plethora of papers reporting subtle but consistent changes in infrared and Raman spectral features of glass upon alterations of glass compositions, thermal histories, mechanical stresses, or surface treatments. However, interpretations of such spectral features are still obscured due to the lack of well‐established physical principles accurately describing vibrational modes of the non‐crystalline glass network. Due to the non‐equilibrium nature of the glass network, three‐dimensionally connected without any long‐range orders, vibrational spectral features of glass cannot be interpreted using the analogy with those of isolated molecular moieties or crystalline counterparts. This feature article explains why such comparisons are outdated and describes the recent advances made from theoretical calculations of vibrational spectral features of amorphous networks or comparisons of computational results with experimental data. For the interpretation of vibrational spectral features of silica and silicate glasses, the following empirical relationships are suggested: (i) the intensity‐weighted peak position of the Si‐O‐Si stretch mode negatively correlates with the weighted average of the Si‐O bond length distribution, and (ii) the broad band of the Si‐O‐Si bending mode negatively correlates with the Si‐O‐Si bond angle distribution. Selected examples of vibrational spectroscopic imaging of surface defects are discussed to deliberate the implication of these findings in the structure‐property relationship of silica and silicate glass materials. Unanswered questions and continuing research challenges are identified.

Increasing Olefin Metathesis Activity of Silica‐Supported Molybdenum Imido Adamantylidene Complexes through E Ligand σ‐Donation

AbstractMolybdenum imido adamantylidene complexes with different substituents on the imido ligand (dipp=2,6‐diisopropylphenyl, ArF5=C6F5, and tBu) having distinct electron donating abilities were investigated for the metathesis of internal and terminal olefins, for both molecular and silica‐supported species using standardized protocols. Here we show that surface immobilization of these compounds results in dramatically increased activity compared to their molecular counterparts. Additionally, we show that electron withdrawing imido groups increase the activity of the compound towards terminal olefins while they simultaneously decrease the ability to metathesize internal olefins. Furthermore, these systems also show high stability when used as initiators in olefin metathesis, although the species that display higher initial activity deactivate faster than those that show more a more moderate reaction rate at first. Our catalytic studies, augmented by DFT calculations, show that all investigated compounds have a remarkably small energy difference between the trigonal bipyramidal (TBP) and square planar (SP) configurations of the metallacyclobutane intermediates, which has previously been linked to high activity.

Renormalization group analysis of the magnetohydrodynamic turbulence and dynamo

The magnetohydrodynamic (MHD) turbulence appears in engineering laboratory flows and is a common phenomenon in natural systems, e.g. stellar and planetary interiors and atmospheres and the interstellar medium. The applications in engineering are particularly interesting due to the recent advancement of tokamak devices, reaching very high plasma temperatures, thus giving hope for the production of thermonuclear fusion power. In the case of astrophysical applications, perhaps the main feature of the MHD turbulence is its ability to generate and sustain large-scale and small-scale magnetic fields. However, a crucial effect of the MHD turbulence is also the enhancement of large-scale diffusion via interactions of small-scale pulsations, i.e. the generation of the so-called turbulent viscosity and turbulent magnetic diffusivity, which typically exceed by orders of magnitude their molecular counterparts. The enhanced resistivity plays an important role in the turbulent dynamo process. Estimates of the turbulent electromotive force (EMF), including the so-called $\alpha$ -effect responsible for amplification of the magnetic energy and the turbulent magnetic diffusion are desired. Here, we apply the renormalization group technique to extract the final expression for the turbulent EMF from the fully nonlinear dynamical equations (Navier–Stokes, induction equation). The simplified renormalized set of dynamical equations, including the equations for the means and fluctuations, is derived and the effective turbulent coefficients such as the viscosity, resistivity, the $\alpha$ -coefficient and the Lorentz-force coefficients are explicitly calculated. The results are also used to demonstrate the influence of magnetic fields on energy and helicity spectra of strongly turbulent flows, in particular the magnetic energy spectrum.

Molecular description of meningeal solitary fibrous tumors/hemangiopericytomas compared to meningiomas: two completely separate entities.

Meningeal solitary fibrous tumors (SFT), like all SFT, are defined by NAB2-STAT6 fusion and share clinicopathologic similarities with meningiomas, the most frequent meningeal tumors. Our aim is to establish the molecular identity of meningeal SFT and seek molecular prognostic factors. RNA sequencing and whole exome sequencing were performed in STAT6-positive SFT and grade 2-3 meningiomas, and data concerning other soft tissues tumors was obtained from the local database. Uniform manifold approximation and projection, individual gene expression and Gene Set Enrichment Analysis were performed. RNA clustering shows that SFT share a common molecular signature, different from any other type of tumoral tissue. Meningeal SFT aggregate with other SFT, with no clinical or histological subgroup. Comparison of genes expressions suggests significant over-expressions of ZIC2, ZIC3, ZIC5, GABBR2, TP53 in CNS-SFT. The pathogenic TP53 c.743G>T variant, previously undescribed in SFT, was found in one sample of meningeal SFT during malignant progression. Meningeal SFT are molecular counterparts of extra-meningeal SFT, completely separate from meningiomas. They might develop from the same tissues and benefit from the same treatments as SFT.

Molecular vibrational polariton: Its dynamics and potentials in novel chemistry and quantum technology.

Molecular vibrational polaritons, a hybridized quasiparticle formed by the strong coupling between molecular vibrational modes and photon cavity modes, have attracted tremendous attention in the chemical physics community due to their peculiar influence on chemical reactions. At the same time, the half-photon half-matter characteristics of polaritons make them suitable to possess properties from both sides and lead to new features that are useful for photonic and quantum technology applications. To eventually use polaritons for chemical and quantum applications, it is critical to understand their dynamics. Due to the intrinsic time scale of cavity modes and molecular vibrational modes in condensed phases, polaritons can experience dynamics on ultrafast time scales, e.g., relaxation from polaritons to dark modes. Thus, ultrafast vibrational spectroscopy becomes an ideal tool to investigate such dynamics. In this Perspective, we give an overview of recent ultrafast spectroscopic works by our group and others in the field. These recent works show that molecular vibrational polaritons can have distinct dynamics from its pure molecular counterparts, such as intermolecular vibrational energy transfer and hot vibrational dynamics. We then discuss some current challenges and future opportunities, such as the possible use of ultrafast vibrational dynamics, to understand cavity-modified reactions and routes to develop molecular vibrational polaritons as new room temperature quantum platforms.

The Genotoxic and Pro-Apoptotic Activities of Advanced Glycation End-Products (MAGE) Measured with Micronuclei Assay Are Inhibited by Their Low Molecular Mass Counterparts.

An association between the cancer invasive activities of cells and their exposure to advanced glycation end-products (AGEs) was described early in some reports. An incubation of cells with BSA–AGE (bovine serum albumin–AGE), BSA–carboxymethyllysine and BSA–methylglyoxal (BSA–MG) resulted in a significant increase in DNA damage. We examined the genotoxic activity of new products synthesized under nonaqueous conditions. These were high molecular mass MAGEs (HMW–MAGEs) formed from protein and melibiose and low molecular mass MAGEs (LMW–MAGEs) obtained from the melibiose and N-α-acetyllysine and N-α-acetylarginine. We have observed by measuring of micronuclei in human lymphocytes in vitro that the studied HMW–MAGEs expressed the genotoxicity. The number of micronuclei (MN) in lymphocytes reached 40.22 ± 5.34 promille (MN/1000CBL), compared to 28.80 ± 6.50 MN/1000 CBL for the reference BSA–MG, whereas a control value was 20.66 ± 1.39 MN/1000CBL. However, the LMW–MAGE fractions did not induce micronuclei formation in the culture of lymphocytes and partially protected DNA against damage in the cells irradiated with X-ray. Human melanoma and all other studied cells, such as bronchial epithelial cells, lung cancer cells and colorectal cancer cells, are susceptible to the genotoxic effects of HMW–MAGEs. The LMW–MAGEs are not genotoxic, while they inhibit HMW–MAGE genotoxic activity. With regard to apoptosis, it is induced with the HMW–MAGE compounds, in the p53 independent way, whereas the low molecular mass product inhibits the apoptosis induction. Further investigations will potentially indicate beneficial apoptotic effect on cancer cells.

Direct Observation of a Plasmon-Induced Hot Electron Flow in a Multimetallic Nanostructure.

Plasmon hot carriers are interesting for photoredox chemical synthesis but their direct utilization is limited by their ultrafast thermalization. Therefore, they are often transferred to suitable accepting materials that expedite their lifetime. Solid-state photocatalysts are technologically more suitable than their molecular counterparts, but their photophysical processes are harder to follow due to the absence of clear optical fingerprints. Herein, the journey of hot electrons in a solid-state multimetallic photocatalyst is revealed by a combination of ultrafast visible and infrared spectroscopy. Dynamics showed that electrons formed upon silver plasmonic excitation reach the gold catalytic site within 700 fs and the electron flow could also be reversed. Gold is the preferred site until saturation of its 5d band occurs. Silver-plasmon hot electrons increased the rate of nitrophenol reduction 16-fold, confirming the preponderant role of hot electrons in the overall catalytic activity and the importance to follow hot carriers’ journeys in solid-state photosystems.

Invasive and non-invasive therapies for Alzheimer's disease and other amyloidosis.

Advancements in medical science have facilitated in extending human lives. The increased life expectancy, though, has come at a cost. The cases of an aging population suffering from degenerative diseases like Alzheimer's disease (AD) are presently at its all-time high. Amyloidosis disorders such as AD are triggered by an abnormal transition of soluble proteins into their highly ordered aggregated forms. The landscape of amyloidosis treatment remains unchanged, and there is no cure for such disorders. However, an increased understanding of the mechanism of amyloid self-assembly has given hope for a possible therapeutic solution. In this review, we will discuss the current state of molecular and non-molecular options for therapeutic intervention of amyloidosis. We highlight the efficacy of non-invasive physical therapies as possible alternatives to their molecular counterparts. Graphical abstract.

De Novo Drug Design of Targeted Chemical Libraries Based on Artificial Intelligence and Pair-Based Multiobjective Optimization.

Artificial intelligence and multiobjective optimization represent promising solutions to bridge chemical and biological landscapes by addressing the automated de novo design of compounds as a result of a humanlike creative process. In the present study, we conceived a novel pair-based multiobjective approach implemented in an adapted SMILES generative algorithm based on recurrent neural networks for the automated de novo design of new molecules whose overall features are optimized by finding the best trade-offs among relevant physicochemical properties (MW, logP, HBA, HBD) and additional similarity-based constraints biasing specific biological targets. In this respect, we carried out the de novo design of chemical libraries targeting neuraminidase, acetylcholinesterase, and the main protease of severe acute respiratory syndrome coronavirus 2. Several quality metrics were employed to assess drug-likeness, chemical feasibility, diversity content, and validity. Molecular docking was finally carried out to better evaluate the scoring and posing of the de novo generated molecules with respect to X-ray cognate ligands of the corresponding molecular counterparts. Our results indicate that artificial intelligence and multiobjective optimization allow us to capture the latent links joining chemical and biological aspects, thus providing easy-to-use options for customizable design strategies, which are especially effective for both lead generation and lead optimization. The algorithm is freely downloadable at https://github.com/alberdom88/moo-denovo and all of the data are available as Supporting Information.

Equi\u2013size nesting of Platonic and Archimedean metal\u2013organic polyhedra into a twin capsid

Inspired by the structures of virus capsids, chemists have long pursued the synthesis of their artificial molecular counterparts through self–assembly. Building nanoscale hierarchical structures to simulate double-shell virus capsids is believed to be a daunting challenge in supramolecular chemistry. Here, we report a double-shell cage wherein two independent metal–organic polyhedra featuring Platonic and Archimedean solids are nested together. The inner (3.2 nm) and outer (3.3 nm) shells do not follow the traditional “small vs. large” pattern, but are basically of the same size. Furthermore, the assembly of the inner and outer shells is based on supramolecular recognition, a behavior analogous to the assembly principle found in double-shell viruses. These two unique nested characteristics provide a new model for Matryoshka–type assemblies. The inner cage can be isolated individually and proves to be a potential molecular receptor to selectively trap guest molecules.

(Thio)urea-Based Covalent Organic Framework as a Hydrogen-Bond-Donating Catalyst.

Two-dimensional urea- and thiourea-containing covalent organic frameworks (COFs) were synthesized at ambient conditions at large scale within 1 h in the absence of an acid catalyst. The site-isolated urea and thiourea in the COF showed enhanced catalytic efficiency as a hydrogen-bond-donating organocatalyst compared to the molecular counterparts in epoxide ring-opening reaction, aldehyde acetalization, and Friedel-Crafts reaction. The COF catalysts also had excellent recyclability.

Kinetic Features of Elementary Events in the Radical Polymerization of Methyl Methacrylate under Conditions of Nitroxide-Mediated Reversible Inhibition

The kinetic features of the elementary events of initiation, reinitiation, and reversible termination in the radical polymerization of methyl methacrylate mediated by piperidine and imidazoline nitroxides are studied. The rate constants of these reactions and the constant of equilibrium between the dormant and growing chains are determined. In all the systems studied, the reinitiation rate constant and the equilibrium constant decrease during polymerization. The activity of imidazoline nitroxides in the termination reaction turns out to be an order of magnitude lower than that of piperidine ones, and the constant of interaction of both types of nitroxides with methyl methacrylate growing radicals is two and a half orders of magnitude lower than that with their low molecular weight counterparts.

The crystal structures of ten supramolecular adducts of benzylamine and organic acids

This article demonstrates the benzylamine based supramolecular adducts formation in ten crystalline solids 1–10, in which the acidic moiety have been integrated. Addition of the organic acid to the solution of benzylamine generates the corresponding supramolecular assemblies. All the compounds crystallize as their organic salts with the acidic H at the acids transferred to the NH2 of the benzylamine. All salts have been characterized via infrared spectroscopy, melting point, elemental analysis and X-ray diffraction analysis technique. The major driving force in 1–10 is attributed to the classical H-bonds from benzylamine and the acids. The other extensive non-covalent interactions also play great functions in space association of the molecular counterparts in relevant crystals. The homo or hetero supramolecular synthons or both were found at these salts and the common R42(8), R43(10) and R44(12) graph sets have been frequently observed in the salts due to the H-bonds and non-covalent associations. For the synergistic effects of the classical H-bonds and the various non-covalent bonds, these salts displayed 2D/3D structures.

Revealing the hidden performance of metal phthalocyanines for CO2 reduction electrocatalysis by hybridization with carbon nanotubes

Metal phthalocyanines (MePcs) have been considered as promising catalysts for CO2 reduction electrocatalysis due to high turnover frequency and structural tunability. However, their performance is often limited by low current density and the performance of some systems is controversial. Here, we report a carbon nanotube (CNT) hybridization approach to study the electrocatalytic performance of MePcs (Me = Co, Fe and Mn). MePc molecules are anchored on CNTs to form the hybrid materials without noticeable molecular aggregations. The MePc/CNT hybrids show higher activities and better stabilities than their molecular counterparts. FePc/CNT is slightly less active than CoPc/CNT, but it could deliver higher Faradaic efficiencies for CO production at low overpotentials. In contrast, the catalytic performance of MePc molecules directly loaded on substrate is hindered by molecular aggregation, especially for FePc and MnPc. Our results suggest that carbon nanotube hybridization is an efficient approach to construct advanced MePc electrocatalysts and to understand their catalytic performance.

Synthesis and characterization of post-sulfonated poly(arylene ether sulfone) membranes for potential applications in water desalination

This study focuses on post-sulfonated polysulfone membranes for potential applications in desalination by reverse osmosis or electrodialysis. A series of controlled molecular weight (5000 and 10,000 g/mol) polysulfones containing hydroquinone and their high molecular weight linear counterparts were synthesized using post-sulfonation of pre-formed polymers under mild conditions. The sulfonic acid groups were substituted on only the hydroquinone units. Amine terminated oligomers were crosslinked with a tetrafunctional epoxy molecule under suitable conditions to form membranes whereas the linear high molecular weight polymers were cast directly to form films with chain entanglements. Fixed charge concentrations of the membranes based on linear copolymers increased from 3.94 to 5.14 meq/mL when the ion exchange capacity was decreased from 1.30 to 0.88 meq/g. The fixed charge concentration of the networks cast from the 5000 g/mol oligomers increased from 4.04 to 6.23 meq/mL with a decrease in the ion exchange capacity from 1.51 to 0.90 meq/g.

Chiral Plasmonic Nanostructures Enabled by Bottom-Up Approaches.

We present a comprehensive review of recent developments in the field of chiral plasmonics. Significant advances have been made recently in understanding the working principles of chiral plasmonic structures. With advances in micro- and nanofabrication techniques, a variety of chiral plasmonic nanostructures have been experimentally realized; these tailored chiroptical properties vastly outperform those of their molecular counterparts. We focus on chiral plasmonic nanostructures created using bottom-up approaches, which not only allow for rational design and fabrication but most intriguingly in many cases also enable dynamic manipulation and tuning of chiroptical responses. We first discuss plasmon-induced chirality, resulting from the interaction of chiral molecules with plasmonic excitations. Subsequently, we discuss intrinsically chiral colloids, which give rise to optical chirality owing to their chiral shapes. Finally, we discuss plasmonic chirality, achieved by arranging achiral plasmonic particles into handed configurations on static or active templates. Chiral plasmonic nanostructures are very promising candidates for real-life applications owing to their significantly larger optical chirality than natural molecules. In addition, chiral plasmonic nanostructures offer engineerable and dynamic chiroptical responses, which are formidable to achieve in molecular systems. We thus anticipate that the field of chiral plasmonics will attract further widespread attention in applications ranging from enantioselective analysis to chiral sensing, structural determination, and in situ ultrasensitive detection of multiple disease biomarkers, as well as optical monitoring of transmembrane transport and intracellular metabolism.

(Invited) Elucidating Ion Transport Mechanisms in Polymerized Ionic Liquids

Poor ionic conductivity typically hinders the utilization of ion containing polymers from functioning as a single ion conductor for energy storage or conversion applications. A provocative sub class of these materials are polymerized ionic liquids (polyILs) which have the potential to combine the desirable ion transport of an ionic liquid with the favorable mechanical properties of a polymer. However, the room temperature conductivity of polyILs is usually 2 or 3 orders of magnitude lower than that of low molecular weight ionic liquids, yet a decoupling of conductivity and structural dynamics in polyILs demonstrates the opposite at the normalized glass transition temperature (T g/T). This seemingly conflicting observation can be reconciled by the fact that polyILs have higher T g and lower dielectric permittivity at the same T g/T than their molecular counterparts. Moreover, ionic conductivity of polyILs is found to be significantly slower than ion diffusion. Inverse Haven ratio shows a strong temperature dependence: saturating at 0.2 at higher temperature and decreasing at lower T. Pronounced reduction in conductivity is attributed to the cross correlation between the mobile ions since the ion pair diffusion is infeasible in polyILs. This speculation remains unverified. We have recently undertaken atomistic molecular dynamics (MD) simulations to elucidate transport mechanism in polyILs and demonstrate the dynamical heterogeneity and cooperative motion of ion transport in polyILs establishing for the first time quantitative evidence of mobile ion hopping. The hopping of anions is found to be dominantly interchain in nature and is generally facilitated by five associating cations from two different chains. Intrachain hopping was found to be much less significant being mediating with fewer chains. The mobile anions tend to form string-like structures and move cooperatively; and the string length of concerted motion of mobile anions increases with decreasing temperature. Our results reveal the important role of a distance criterion in defining hopping events to correctly elucidate the components of the ion transport mechanism. This molecular-level information will provide an important step in both rationalizing experimental observations and the design of novel ion-containing polymers with superior transport properties.