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The side chain dynamics of poly(quinoxaline-2,3-diyl)s (PQXs) are expected to influence their conformation. To investigate these dynamics experimentally, quasielastic neutron scattering (QENS) was performed for PQXs in deuterated tetrahydrofuran (THF-d8) and deuterated 1,1,2-trichloroethane/THF (1,1,2-TCE-d3/THF-d8), in which they formed right-handed and left-handed helical structures, respectively. The mean-square displacement of the PQX side chains in 1,1,2-TCE-d3/THF-d8 was lower than that in THF-d8. Furthermore, QENS complementary studies and molecular dynamics simulations unraveled a coupling between the main-chain and side chain dynamics of PQXs, suggesting the possibility of controlling the main-chain helical chirality through the dynamics of chiral side chains. These insights present a novel strategy for the design of synthetic helical macromolecules with precise chirality control. [ABSTRACT FROM AUTHOR]

Carbon nanotubes (CNTs) have potential applications in separation membranes and nanofluidic devices. It is well known that the behavior of water molecules confined in CNTs is affected by surface functional groups and external electric fields, leading to structural changes. The understanding of these structural changes of water within various CNTs is crucial, particularly in the context of material separation. While there have been many investigations into the effects of individual specific functional groups, a comprehensive understanding of the effect of these functional groups and the electric fields they generate on water molecules remains elusive. In this study, we investigate the properties of water molecules in tip-charged CNTs of (8,8), (10,10), and (12,12) chiral vectors with positive charges at one tip and negative charges at the other tip. Abstraction of ionized functional groups as tip charges enables a comprehensive understanding that is independent of individual functional groups. The symmetrically arranged tip-charges spontaneously generate a strong and symmetric electric field in the CNTs. However, the strength and directionality of the electric field are non-uniform and complex. In the interiors of (8,8) and (10,10) tip-charged CNTs, helical and square structures, which have disturbances caused by the non-uniformity of the electric field, are observed. The properties of the water molecules differed significantly in the center of the CNTs and near positive and negative charges, despite the electric field symmetry. In (12,12) tip-charged CNTs with 12 charges, a local ring structure is observed in the vicinity of negative charges but not in the vicinity of positive charges. It is concluded that the water structures in tip-charged CNTs have different characteristics from those in plain CNTs under a uniform electric field. [ABSTRACT FROM AUTHOR]

Motivated by the booming development of spintronics based on chiral helical microstructures, we employed the standard nonequilibrium Green's function theory to study nonreciprocity and chirality of the heat generation and spin filtering in ferromagnetic helical chains. Our results demonstrate that magnetization, spin–orbit interaction, and nonstep electrostatic potential distribution by bias jointly determine nonreciprocity of the heat generation, and only spin–orbit interaction determines nonreciprocity of the spin-polarized current. Chirality of the heat generation and spin-polarized current is determined by both magnetization and spin–orbit interaction, and some quantitative relationships related to chirality were discovered. However, a transverse field can break these relations and suppress heat generation significantly and modulate nonreciprocity and chirality of the spin-polarized current effectively. By further simulating the critical electrostatic potential distribution, we found with the transverse field applied, compared to the case with zero temperature, that the finite temperature less than one characteristic phonon energy can suppress nonreciprocity of the heat generation while enhancing that of the spin filtering. In terms of chirality, compared to the left-handed helical structure, the right-handed one is more advantageous for designing spin filtering diodes. [ABSTRACT FROM AUTHOR]

We study theoretically the electronic structure of three-dimensional (3D) higher-order topological insulators in the presence of step edges. We numerically find that a 1D conducting state with a helical spin structure, which also has a linear dispersion near the zero energy, emerges at a step edge and on the opposite surface of the step edge. We also find that the 1D helical conducting state on the opposite surface of a step edge emerges when the electron hopping in the direction perpendicular to the step is weak. In other words, the existence of the 1D helical conducting state on the opposite surface of a step edge can be understood by considering an addition of two different-sized independent blocks of 3D higher-order topological insulators. On the other hand, when the electron hopping in the direction perpendicular to the step is strong, the location of the emergent 1D helical conducting state moves from the opposite surface of a step edge to the dip (270 ° edge) just below the step edge. In this case, the existence at the dip below the step edge can be understood by assigning each surface with a sign (+ or −) of the mass of the surface Dirac fermions. These two physical pictures are connected continuously without the bulk bandgap closing. Our finding paves the way for on-demand creation of 1D helical conducting states from 3D higher-order topological insulators employing experimental processes commonly used in thin-film devices, which could lead to, e.g., a realization of high-density Majorana qubits. [ABSTRACT FROM AUTHOR]

Confined liquid crystals (LCs) exhibit complex and intriguing structures, which are fascinating fundamental problems in soft matter. The helical structure of cylindrical cavities is of great importance in LC studies, particularly for their application in optical devices. In this study, we employ molecular dynamics simulations to explore the behavior of achiral smectic-B LCs confined in narrow cylindrical cavities, where geometric frustration plays an important role. By increasing the cylinder size, LCs exhibit a transition from multi-helical to layered structures. Notably, we observe two stable structures, namely the helical structure and the layered structure, at moderate cylinder size. We also investigate the effects of the arrangement of cylindrical wall particles (hexagonal or square array) and anchoring strength on the LC structure. Our findings reveal that both the hexagonal array and strong anchoring strength promote the formation of helical structures. Our study provides novel insights into the confinement physics of LCs and highlights the potential for achieving helical structures in achiral LCs, which will expand the future applications of LCs. [ABSTRACT FROM AUTHOR]

Ceramic aerogel with high porosity and low thermal conduction was widely used in the field of thermal insulation. However, shrinkage and structural damage were produced by the ceramic precursors during pyrolysis. The shrinkage and mechanical properties of ceramic aerogels required to be improved. Herein, inspired by spiral grass and passionflower, curvature-ordered ceramic fiber aerogels were prepared by electrostatic spinning combined with polymer-derived ceramics (PDCs) route. Shrinkage resistance properties, thermal insulation properties, and mechanical properties of ceramic fiber aerogels were investigated. The shrinkage resistance property of aerogels was improved by the tensile deformation of helical fibers during pyrolysis. The path of heat transfer was extended through the helical fibers and heat conduction was reduced. The gas was confined in a porous network formed by helical fibers that lapped over each other, and thermal convection was minimized. Thermal radiation was attenuated due to reflection and scattering at the core-shell interface of the helical fibers. The mechanical properties of the aerogel were enhanced by the helical structure of the fibers and the stress diffusion mechanism. The tensile and compressive properties of the spiral ceramic aerogel were improved through the curvature structure by about 6 MPa and 3 MPa, respectively. The results showed that the helical ceramic composite fiber aerogel with ordered curvature exhibited shrinkage resistance, thermal insulation, and mechanical properties. [ABSTRACT FROM AUTHOR]

Synthetic duplexes with high stabilities have promising potential for mimicking biomolecular functions and developing supramolecular smart materials. Herein, we describe the synthesis and stimuli‐responsive properties of molecular duplexes derived from indolocarbazole–pyridine (I−P) oligomers. These duplexes adopt nonclassical helical structures, stabilized by I−P hydrogen‐bonding pairs in anhydrous chlorinated solvents. Notably, the longest duplex 62 (11‐mer)2 displays remarkable stability, forming twenty hydrogen bonds; its exchange energy barrier was determined to be ΔG≠=22.0 kcal ⋅ mol−1 at 75 °C in anhydrous (CDCl2)2. Upon the addition of water, a hydrated duplex 62 (11‐mer)2⊃10H2O was formed, with one water molecule inserted between each I−P hydrogen‐bonding pair. The Hill coefficient (n) for this process is 6.1, demonstrating extremely positive cooperativity. Conversely, the hydrated duplex 62 (11‐mer)2⊃10H2O was completely converted into the original anhydrous duplex 62 (11‐mer)2 when the temperature was increased. Interconversion between these two distinct duplexes can be repeatedly carried out by varying the temperature. Furthermore, reversible switching between hetero‐duplexes and homo‐duplexes was also demonstrated by controlling the temperature, with concomitant changes in the characteristic emission signals. [ABSTRACT FROM AUTHOR]

We herein report five coordination polymers (CPs) and two supramolecular cages based on [MS4Cux]x−2 (M = W, Mo, x = 1, 2, ... 6) units and N-containing ligands, 9,10-di(1H-imidazol-1-yl)anthracene (dia), 1,6-di(1H-imidazol-1-yl)pyrene (dip), and 1,1′,1′′-(benzene-1,3,5-triyltris(methylene))tris(1,4-diazabicyclo[2.2.2]octan-1-ium) bromide (bmd), and 1,1′,1′′-((2,4,6-trimethylbenzene-1,3,5-triyl)tris(methylene))tris(1,4-diazabicyclo[2.2.2]octan-1-ium) (mbmd). Compounds 1 and 2 both contain the penta-nuclear [(WS4)Cu4]2+ cluster unit. The four Cu+ atoms were arranged in a distorted tetrahedron and rectangle around the (WS4)2− core in 1 and 2, respectively, affording a 3-connected unit in 1 and a 2-connected unit in 2. Compounds 3, 4 and 5 were built with the tri-topic organic ligand bmd; 3 and 4 contain penta-nuclear [WS4Cu4]2+ units, and 5 contains the hexa-nuclear [MoS4Cu5]3+ unit. However the connectives of the cluster units in 3, 4 and 5 and the final helical chain structures were similar. Compound 6 contains a tetra-nuclear [WS4Cu3I3]2− unit and positively charged mbmd ligand. The mbmd ligand was in a cis-conformation leading to a supramolecular cage, which accommodated an I− anion as guest. Compound 7 is isostructural to 6 but contains a [WS4Cu3Cl3]2− cluster unit, mbmd ligand and a Br− free anion. This work demonstrates that the number and arrangement of Cu+ around the (MS4)2− core can be varied with the synthesis conditions, affording heterothiometallic [(MS4)Cux]x−2 cluster units of versatile geometries and connectivities for building CPs. [ABSTRACT FROM AUTHOR]

A novel room‐temperature liquid crystal of tetraphenylethylene derivative (TPE‐DHAB) was synthesized using an ionic self‐assembly strategy. The TPE‐DHAB complex exhibits typical aggregation‐induced emission properties and a unique helical supramolecular structure. Moreover, the generation and handedness inversion of circularly polarized luminescence (CPL) can be achieved through further chiral solvation, providing a facile approach to fabricate room‐temperature liquid crystalline materials with controllable supramolecular structures and tunable CPL properties through a synergistic strategy of ionic self‐assembly and chiral solvation process. [ABSTRACT FROM AUTHOR]

We present Atacama Large Millimeter/submillimeter Array (ALMA) observations of the binary Class 0 protostellar system BHR 71 IRS1 and IRS2 as part of the Early Planet Formation in Embedded Disks (eDisk) ALMA Large Program. We describe the 12CO (J = 2–1), 13CO (J = 2–1), C18O (J = 2–1), H2CO (J = 32,1–22,0), and SiO (J = 5–4) molecular lines along with the 1.3 mm continuum at high spatial resolution (∼0.″08 or ∼5 au). Dust continuum emission is detected toward BHR 71 IRS1 and IRS2, with a central compact component and extended continuum emission. The compact components are smooth and show no sign of substructures such as spirals, rings, or gaps. However, there is a brightness asymmetry along the minor axis of the presumed disk in IRS1, possibly indicative of an inclined geometrically and optically thick disk-like component. Using a position–velocity diagram analysis of the C18O line, clear Keplerian motions were not detected toward either source. If Keplerian rotationally supported disks are present, they are likely deeply embedded in their envelope. However, we can set upper limits of the central protostellar mass of 0.46 M ⊙ and 0.26 M ⊙ for BHR 71 IRS1 and BHR 71 IRS2, respectively. Outflows traced by 12CO and SiO are detected in both sources. The outflows can be divided into two components, a wide-angle outflow and a jet. In IRS1, the jet exhibits a double helical structure, reflecting the removal of angular momentum from the system. In IRS2, the jet is very collimated and shows a chain of knots, suggesting episodic accretion events. [ABSTRACT FROM AUTHOR]

We report the reversible transformation between a singly stapled dynamic α‐helical peptide and a doubly stapled quasi‐static one through redox‐triggered dithiol/disulfide conversions of a stapling moiety. This process allows the rate of interconversion between the right‐handed (P) and left‐handed (M) α‐helices to be altered by a factor of approximately 103 before and after the transformation. An as‐obtained doubly stapled α‐helical peptide, which is composed of an achiral peptide having an l‐valine carboxylic acid residue at the C‐terminus, a disulfide‐based reversible staple, and a biphenyl‐based fixed staple, adopts an (M)‐rich form as a kinetically trapped state. The (M)‐rich helix was subsequently transformed into the thermodynamically stable (P)‐rich form in 1,1,2,2‐tetrachloroethane with the half‐life time (t1/2) of approximately 44 days at 25 °C. Reduction of the doubly stapled peptide with tri‐n‐butylphosphine in tetrahydrofuran/water (10/1, v/v) produced the corresponding singly stapled dynamic α‐helical peptide bearing two thiol groups at the side chains, which underwent solvent‐induced reversible helicity inversion. The resulting dithiol of the singly stapled peptide could be reoxidized to form the original doubly stapled form using 4,4'‐dithiodipyridine. Furthermore, the P/M interconversion of a doubly stapled peptide with two flexible hydrocarbon‐based staples is considerably more rapid than that with more rigid staples. [ABSTRACT FROM AUTHOR]

Helicenes, with their unique helical structures, have long captured the interest of synthetic chemists, not only as end products, but also as versatile platforms for further chemical transformations. However, transforming [6]helicene into planar coronene typically requires harsh conditions and poses significant challenges. Herein, we demonstrate that replacing the terminal benzene ring of [6]helicene with a thiophene ring enables its photochemical transformation into coronene. Sulfur oxidation of the thiophene ring enables the corresponding thermal transformation, and the terminal tetrafluorination of the opposite benzene ring further accelerates this process, yielding 1,2‐difluorocoronene, as confirmed by X‐ray crystallography. The transformation begins with an intramolecular Diels–Alder reaction, whose activation energy is significantly lowered by these structural changes. Our findings underscore the utility of strategic modifications such as sulfur oxidation and fluorination in promoting this "helix‐to‐disc" conversion and opening new avenues for synthesizing functional polycyclic aromatics. [ABSTRACT FROM AUTHOR]

The interaction of opposite-signed twist waves on vortex tubes can lead to vortex bursting, a process where the core expands into a double ring-like structure with strong swirling flows. Previous works have studied vortex bursting on rectilinear vortices by axially perturbing the initial core size to generate the twist waves, and observed largely axisymmetric bursting dynamics. In this work, we numerically study bursting on vortical structures with curved centrelines, analysing the interaction between the centreline dynamics, twist wave generation and propagation, and vortex bursting. We focus on axially perturbed helical vortex tubes with small radius-to-pitch ratios up to $0.0625$ , as well as vortex rings with a large radius-to-core size ratio $10$ , both at a circulation-based Reynolds number $5000$. The results show that though the initial twist wave propagation speeds are relatively unaffected by the curvature and torsion of the centreline, the bursting process is altered significantly compared with rectilinear vortices. The self-induced rotation of the centreline of the helical tube induces a non-axisymmetric distortion of the bursting structure, which rapidly breaks up the vortex core into small-scale helical structures. A similar destabilization of the bursting structure also occurs on vortex rings. The enstrophy increase and accelerated energy decay associated with bursting are predominantly determined by the twist wave strength, rather than the curvature and torsion of the centreline. Combined, our findings imply that bursting could play an important role in transferring and dissipating energy of vortical structures in wakes, and turbulent flows in general. [ABSTRACT FROM AUTHOR]

Cf/SiC composites are widely utilized in the aerospace industry due to their excellent properties. However, Cf/SiC composites are notoriously challenging to machine. The substantial cutting force and severe tool wear during machining often result in poor surface quality and low machining efficiency. This paper presented a corrugated helical PCD (polycrystalline diamond) tool, featuring a helical structure and an arc array micro-groove on the primary cutting edge, and these micro-groove structures are staggered, facilitating continuous material removal during the machining of Cf/SiC composites. The study investigated the milling force variations of the corrugated helical PCD tool when machining Cf/SiC composites under different milling parameters. A comparative study was conducted on the milling force, surface quality, and tool wear of corrugated helical PCD tool and commercial PCD tools. The experiment revealed that the milling force initially decreases and then increases with rising spindle speed and increases with higher feed rates per tooth, milling depth, and width. The newly designed tool exhibited lower milling force, superior machining surface quality, and extended tool life, approximately 0.7 times that of commercial PCD tools. The cutting performance of the corrugated helical PCD tool proved superior. Additionally, it was confirmed that the primary wear mechanism for the corrugated helical PCD tool cutting Cf/SiC composites was abrasive wear. [ABSTRACT FROM AUTHOR]

Dry liquid crystal marbles, thermotropic liquid crystal droplets encapsulated by cellulose nanocrystals, exhibit fast response to an external stimuli. [Display omitted] Dry liquid crystal marbles are structures that consist of cholesteric liquid crystal (CLC) droplets prepared by the mixture of chiral-doped thermotropic LCs encapsulated by cellulose nanocrystals (CNCs) that have been dried under ambient conditions. The characterizations revealed that CLC droplets were successfully encapsulated by self-standing CNC shells and responsive to the external gaseous stimulus. The dry LC marbles offer several advantages over previously reported LC-based gas sensors, such as fast response against minor external stimuli, and ease of handling, which make them particularly attractive for practical applications in sensing. We demonstrate the use of these marbles for detecting toluene vapor, a common industrial solvent and pollutant, which we also use to understand the response characteristics. The dry CLC marbles exhibit a significant response to toluene vapor with a detection limit below 500 ppm, attributed to the change of pitch size of the helical structure of CLC droplets induced by the toluene vapor. The CNC-capsulated CLC droplets were stable in emulsion for up to two weeks, and their dried form exhibited a sensitive response upon toluene exposure. The real-time experiments revealed that the LC marbles can be used multiple times without a significant loss of sensitivity, where 90 % of the maximum response was observed at 13.3 ± 4.7 s. These dry LC marbles can also be utilized in other areas, including drug delivery, optical devices, and biosensors. [ABSTRACT FROM AUTHOR]

Hetian rose polysaccharides, Kushui rose polysaccharides and Pingyin rose polysaccharides were extracted and obtained respectively, and the crude polysaccharide yield and polysaccharide content were determined. The polysaccharide structure was characterized using ion chromatograph, Fourier transform infrared spectroscopy and high performance liquid chromatography coupled with multi-angle laser scattering method. Cosmetic-related activities were analyzed using in vitro antioxidant, prebiotic and tyrosinase inhibition assays. The results showed that the crude polysaccharide yield of Hetian rose was higher than that of Kushui rose and Pingyin rose (P<0.05), and the polysaccharide content in the crude polysaccharide of Pingyin rose was lower (P<0.05). All three rose polysaccharides contained 11 types of monosaccharide residues (with different molar ratios), including Glc, Ara, Gal and Fru. Their weight-averaged molecular weights ranged from 4.376x105 to 5.841x105 Da (dispersity index: 1.35~1.72). They were all pyranose containing α and β configurations. They all had nontriple helical spiral structures and multi-branched. The activity evaluation experiments showed that all three rose polysaccharides had good antioxidant activity, prebiotic effect and tyrosinase inhibition activity. Among the three rose polysaccharides, Pingyin rose polysaccharide had strong ABTS+ and DPPH free radical scavenging activities (P<0.05), while Hetian rose polysaccharide had strong tyrosinase inhibition activity (P<0.05). Therefore, the three rose polysaccharides were similar in structure, and their structural differences led to slight differences in biological activities. The three types of rose polysaccharides had good development and application prospects in the field of cosmetic functional foods. [ABSTRACT FROM AUTHOR]

Materials exhibiting a spontaneous reversal of spin chirality have the potential to drive the widespread adoption of chiral magnets in spintronic devices. Unlike the majority of chiral magnets that require the application of an external field to reverse the spin chirality, we observe the spin chirality to spontaneously reverse in the topological magnet EuAl4. Using resonant elastic x-ray scattering we demonstrate that all four magnetic phases in EuAl4 are single-k, where the first two magnetic phases are characterized by spin density wave order and the last two by helical spin order. A single spin chirality was stabilised across the 1mm2 sample, and the reversal of spin chirality occurred whilst maintaining a helical magnetic structure. At the onset of the helical magnetism, the crystal symmetry lowers to a chiral monoclinic space group, explaining the asymmetry in the chiral spin order, and establishing a mechanism by which the spin chirality could reverse via magnetostructural coupling. The reversal of spin chirality in the absence of any externally applied field would substantially broaden the use of chiral magnets for applications in spintronic devices. In this manuscript the authors demonstrate the spontaneous reversal of spin chirality in the topological magnet EuAl4 using resonant elastic x-ray scattering. [ABSTRACT FROM AUTHOR]

Materials exhibiting a spontaneous reversal of spin chirality have the potential to drive the widespread adoption of chiral magnets in spintronic devices. Unlike the majority of chiral magnets that require the application of an external field to reverse the spin chirality, we observe the spin chirality to spontaneously reverse in the topological magnet EuAl4. Using resonant elastic x-ray scattering we demonstrate that all four magnetic phases in EuAl4 are single-k, where the first two magnetic phases are characterized by spin density wave order and the last two by helical spin order. A single spin chirality was stabilised across the 1mm2 sample, and the reversal of spin chirality occurred whilst maintaining a helical magnetic structure. At the onset of the helical magnetism, the crystal symmetry lowers to a chiral monoclinic space group, explaining the asymmetry in the chiral spin order, and establishing a mechanism by which the spin chirality could reverse via magnetostructural coupling. The reversal of spin chirality in the absence of any externally applied field would substantially broaden the use of chiral magnets for applications in spintronic devices. In this manuscript the authors demonstrate the spontaneous reversal of spin chirality in the topological magnet EuAl4 using resonant elastic x-ray scattering. [ABSTRACT FROM AUTHOR]

The equimolar reaction between 1,9-bis(N,N-dimethylaminomethyl)-5,5′-diphenyldipyrromethane, H2L1 or 1,9-bis(3,5-dimethylpyrazolylmethyl)-5,5′-diethyldipyrromethane, H2L2 and [NiCl2(DME)] in the presence of KH yielded the neutral mononuclear nickel(II) complexes [Ni(L1)-κ4N,N,N,N], 1 and [Ni(L2)-κ4N,N,N,N], 2, respectively. Their X-ray structures revealed the formation of triple chelation by the ligand in both structures with quite different nickel(II)-surrounded square planar geometries owing to the steric difference between –NMe2 and 3,5-dimethylpyrazolyl groups. While the –NMe2 group substituted ligand L1 afforded nickel complex 1 with a plane of symmetry, 3,5-dimethylpyrazole substituted L2 rendered helical chirality in the structure of complex 2. Both the enantiomers (Δ and Λ) of complex 2 were observed in the crystal lattice. Their solution state behaviors were consistent with the solid-state structures as monitored by 1H NMR spectroscopy. Both the enantiomers of complex 2 were present in a dynamic equilibrium in solution and studied by variable temperature 1H NMR spectroscopy. Similar to the chiral complex, the corresponding ligand H2L2 also exhibited chirality as shown by its crystal structure and the two ligand enantiomers participated in a very fast dynamic interconversion, which became slower upon metalation. [ABSTRACT FROM AUTHOR]

Developing long‐chain molecules with stable helical structures is of significant importance for understanding and modulating the properties and functions of helical biological macromolecules, but challenging. In this work, an effective and facile approach to stabilize folded helical structures by strengthening through‐space conjugation is proposed, using new ortho‐hexaphenylene (o‐HP) derivatives as models. The structure–activity relationship between the through‐space conjugation and charge‐transport behavior of the prepared folded helical o‐HP derivatives is experimentally and theoretically investigated. It is demonstrated that the through‐space conjugation within o‐HP derivatives can be strengthened by introducing electron‐withdrawing pyridine and pyrazine rings, which can effectively stabilize the helical structures of o‐HP derivatives. Moreover, scanning tunneling microscopy‐break junction measurements reveal that the stable regular helical structures of o‐HP derivatives open‐up dominant through‐space charge‐transport pathways, and the single‐molecule conductance is enhanced by more than 70 % by strengthening through‐space conjugation with pyridine and pyrazine. However, the through‐bond charge transport pathways contribute much less to the conductance of o‐HP derivatives. These results not only provide a new method for exploring stable helical molecules, but also provide a stepping stone for deciphering and modulating the charge‐transport behavior of helical systems at the single‐molecule level. [ABSTRACT FROM AUTHOR]

Ferro‐rotational (FR) materials, renowned for their distinctive material functionalities, present challenges in the growth of homo‐FR crystals (i.e., single FR domain). This study explores a cost‐effective approach to growing homo‐FR helimagnetic RbFe(SO4)2 (RFSO) crystals by lowering the crystal growth temperature below the TFR threshold using the high‐pressure hydrothermal method. Through polarized neutron diffraction experiments, it is observed that nearly 86% of RFSO crystals consist of a homo‐FR domain. Notably, RFSO displays remarkable stability in the FR phase, with an exceptionally high TFR of ≈573 K. Furthermore, RFSO exhibits a chiral helical magnetic structure with switchable ferroelectric polarization below 4 K. Importantly, external electric fields can induce a single magnetic domain state and manipulate its magnetic chirality. The findings suggest that the search for new FR magnets with outstanding material properties should consider magnetic sulfates as promising candidates. [ABSTRACT FROM AUTHOR]

Curved cell shapes are widespread among bacteria and important for cellular motility, virulence and fitness. However, the underlying morphogenetic mechanisms are still incompletely understood. Here, we identify an outer-membrane protein complex that promotes cell curvature in the photosynthetic species Rhodospirillum rubrum. We show that the R. rubrum porins Por39 and Por41 form a helical ribbon-like structure at the outer curve of the cell that recruits the peptidoglycan-binding lipoprotein PapS, with PapS inactivation, porin delocalization or disruption of the porin-PapS interface resulting in cell straightening. We further demonstrate that porin-PapS assemblies act as molecular cages that entrap the cell elongation machinery, thus biasing cell growth towards the outer curve. These findings reveal a mechanistically distinct morphogenetic module mediating bacterial cell shape. Moreover, they uncover an unprecedented role of outer-membrane protein patterning in the spatial control of intracellular processes, adding an important facet to the repertoire of regulatory mechanisms in bacterial cell biology. Curved cell shapes are common among bacteria, but the underlying morphogenetic mechanisms are incompletely understood. Here, the authors identify an outer-membrane protein complex that promotes cell curvature in Rhodospirillum rubrum by forming helical ribbon structures that modulate the dynamics of cell wall biosynthesis, biasing cell growth towards the cell's outer curve. [ABSTRACT FROM AUTHOR]

A comprehensive study was conducted on four aged leather pieces of British origin that were utilized in book binding, dating back to the period between 1832 and 1860. The objective of this study was to characterize the thermal, structural, and deterioration properties of these historical leather fragments. Additionally, this study included two newly acquired leather samples of Indian provenance, proposed as potential replacements for this historical leather. The investigative process employed Differential Scanning Calorimetry (DSC), Fourier Transform Infrared Spectroscopy (FTIR), X-ray Diffraction (XRD), and Scanning Electron Microscopy with Energy Dispersive X-ray Spectroscopy (SEM-EDX). Through the FTIR analysis, distinct spectral shifts were identified in the amide A band, indicating a disruption of hydrogen bonding within the aged leather. XRD diffractograms revealed the presence of amorphous phases in the aged leather specimens, signifying the deterioration of their triple helical structure. Notably, DSC analysis provided insight into the denaturation of the collagen-tannin matrix inherent to the historical leather, underlining the transformative effects of time on this intricate material composition. Under SEM analysis, cracks, fibre deterioration, and a general weakening in structural integrity were observed in the aged leather fragments. The EDX data identified one of the new leather samples as chrome-tanned, while the remaining samples exhibited characteristics consistent with vegetable-tanned leather. [ABSTRACT FROM AUTHOR]

The N-terminal region of the human lysine-specific demethylase 1 (LSD1) has no predicted structural elements, contains a nuclear localization signal (NLS), undergoes multiple posttranslational modifications (PTMs), and acts as a protein-protein interaction hub. This intrinsically disordered region (IDR) extends from core LSD1 structure, resides atop the catalytic active site, and is known to be dispensable for catalysis. Here, we show differential nucleosome binding between the full-length and an N terminus deleted LSD1 and identify that a conserved NLS and PTM containing element of the N terminus contains an alpha helical structure, and that this conserved element impacts demethylation. Enzyme assays reveal that LSD1’s own electropositive NLS amino acids 107 to 120 inhibit demethylation activity on a model histone 3 lysine 4 dimethyl (H3K4me2) peptide (Kiapp∼3.3μM) and histone 3 lysine 4 dimethyl nucleosome substrates (IC50 ∼ 30.4μM), likely mimicking the histone H3 tail. Further, when the identical, inhibitory NLS region contains phosphomimetic modifications, inhibition is partially relieved. Based upon these results andbiophysical data, a regulatory mechanism for the LSD1-catalyzed demethylation reaction is proposed whereby NLS-mediated autoinhibition can occur through electrostatic interactions, and be partially relieved through phosphorylation that occurs proximal to the NLS. Taken together, the results highlight a dynamic and synergistic role for PTMs, intrinsically disordered regions, and structured regions near LSD1 active site and introduces the notion that phosphorylated mediated NLS regions can function to fine-tune chromatin modifying enzyme activity. [ABSTRACT FROM AUTHOR]

Protein glycation is directly associated with many pathological conditions. This study investigated the potential of Eryngium billardierei extract to inhibit the glycation process in human serum albumin (HSA). After preparation of the ethanolic extract of E. billardierei, the structural changes of glycated HSA in the absence and presence of different concentrations of E. billardierei extract were investigated using circular dichroism (CD), fluorescence spectroscopy and UV-Vis spectroscopy. The results confirmed that E. billardierei extract could reduce the formation of advanced glycation end products (AGEs) and Amadori products under in vitro glycation conditions and also improve HSA helical structure. In addition, a reduction in the HSA-cross amyloid formation was seen in the thioflavin T assay. The phytochemical analysis disclosed that E. billardieri extract is high in flavonoid and phenolic compounds. Accordingly, it could be concluded that the phenolics in E. billardieri extract could prevent glucose-induced HSA glycation. This study provides the rationale that E. billardieri extract could be implicated in controlling diabetes. [ABSTRACT FROM AUTHOR]

Laguerre-Gaussian beams possess a unique transverse mode structure defined by the orbital l and radial m mode numbers, offering promising potential for controlling nonlinear optical interactions. This comprehensive study aims to elucidate the crucial influence of this transverse mode structure on the nonlinear absorption processes. We first established a rigorous theoretical framework by deriving analytical expressions describing the behavior of the Open Z-scan normalized optical transmittance for an arbitrary nth-order nonlinear process under the weak nonlinearity approximation, accounting for the transmitted optical intensity, power, and their dependency on the beam's transverse mode profile. In the numerical simulations, we focused on the specific case of second-order ( n = 2 ) nonlinear absorption. Subsequently, detailed numerical simulations were employed to systematically analyze the intricate interplay between the l and m mode indices and their impact on the transmittance characteristics. By precisely varying these indices, we investigated how the observed transmission profiles were affected, revealing distinct behaviors for different Laguerre-Gaussian modes. When only m increases, absorption decreases due to the wider transverse energy spread, while varying l leads to a non-monotonic trend involving intense lobes. Remarkably, simultaneously increasing both l and m systematically enhances absorption through constructive interference of the helical and ring-like structures. [ABSTRACT FROM AUTHOR]

Starch‐guest molecule amylose inclusion complexes (AIC) are of interest to industry as a means to encapsulate and deliver compounds. Coconut fatty acids (CFA) consist predominantly of medium chain fatty acids having useful food and nonfood applications. This article describes the formation of high amylose corn (HAC)‐ or waxy corn starch (WC)‐CFA AIC containing 0%, 2%, 7.5%, and 15% CFA using a continuous thermomechanical extrusion process at 20% feed moisture and a twin‐screw extruder with a unique screw design. The extrusion conditions completely destructure both the HAC and waxy starch granules and the resulting materials are evaluated using SEM, XRD, FT‐IR, FTIR‐m, and TGA. The HAC‐CFA materials are shown to contain AIC having 61 V type helical structure between amylose and the CFA that are confirmed by XRD and IR spectral analysis. By TGA, extruded HAC materials containing 15% CFA are shown to have excess CFA present in addition to formed AIC. In contrast, the WC is shown not to form AIC with the CFA and only trap the CFA within the starch matrix. The understanding gained from this study is helpful to design the processing of starch‐based biopolymers to prepare AIC having improved functional properties for potential commercial applications. [ABSTRACT FROM AUTHOR]

Wastewater remaining in pipes for extended periods can create anaerobic environments, fostering the growth of anaerobic bacteria and producing harmful gases such as methane and hydrogen sulfide. Additionally, certain structures within drainage systems, such as drop shafts and vertical shafts, induce turbulent flow, causing the release of dissolved harmful gases, which pose significant risks to public health and urban infrastructure. This study focused on the investigation and analysis of vertical shafts with helical tray structures in drainage systems. Using ANSYS 2021 R2 software, simulations of the shafts were conducted by employing the standard k-ε turbulence model and Eulerian multiphase flow method to simulate the shaft's operation and obtain various parameters of hydrogen sulfide release. Concurrently, a scale model constructed in the laboratory was used to study and analyze the release of hydrogen sulfide gas dissolved in water from this type of structure. Combining the simulation and laboratory experiments, the hydrogen sulfide gas release rate from water in this structure was 0.05–0.4%. This research provides a reference for the study and control of hydrogen sulfide gas release. [ABSTRACT FROM AUTHOR]

The use of airships to launch space probes has been an effective means of conducting typhoon surveys in recent years, but the carrying area and weight of airships are very limited, so it is necessary to reduce the weight and volume of the release device as much as possible. This paper reports the first use of a probe with cylindrical and omnidirectional characteristics, as well as a four-arm spiral receiving antenna, which can also act as the downward release device of the inner wall and improve the space utilization rate. Through further analysis and improvement, it was determined that the four-armed helical antenna can be printed on the medium using a flexible material, which not only reduces the weight of the device but also avoids direct contact between the antenna and the sounding device and improves the stability of the antenna. The designed antenna was modeled and simulated using Ansys HFSS 2021 simulation software.The simulation results show that the antenna presented in this study achieves good performance at the center frequency of 403 MHz, the input voltage VSWR and return loss of the antenna are ideal, and the antenna has a good directional map. [ABSTRACT FROM AUTHOR]

Highlights The energy conversion mechanism is thoroughly analyzed, with a detailed quantitative characterization of the dissipation capacities of polarization, conduction, and magnetic loss. Inspired by DNA transcription, atom and geometry configurations co-modulating multi-scale helical converters achieve the RL min of −63.13 dB at 1.29 mm, and the maximum RCS reduction value reach 36.4 dB m2. Orbital coupling, spin and cross polarization synergize to realize a 6.08 GHz EAB, further expanding to ultrabroad electromagnetic wave absorption of 12.16 GHz through metamaterial design.

Electron transport through a variety of helical structures has been shown to exhibit high-efficiency spin filtering, which is called chirality-induced spin selectivity (CISS). In this paper, we consider a helical chain of atomic p orbitals, which has been employed as a model in exploring the mechanism of CISS in previous theories, and show that the interatomic hopping along the helical chain induces an effective magnetic field (EMF) acting on the atomic orbital angular momentum (OAM). In chains where the curvature and torsion of the helix are small, we find that the EMF on the binormal component of the atomic OAM is created by the curvature, while that on the tangential component is produced by the torsion. We show that such coupling of the atomic OAM and the interatomic hopping leads to current-induced orbital and spin polarizations. We expect that the present coupling, which is expressed locally, can be used to estimate orbital and spin polarizations locally induced in molecules and solids. [ABSTRACT FROM AUTHOR]

Observations of a high spin selectivity in various helical structures, which is called the chirality-induced spin selectivity, suggest a common mechanism originating from the helical geometry. In this paper, we consider a helical chain of atomic p± orbitals having the tangential angular momentum l = ±1. We show in this model that the coupling of l and the spin gives rise to spin-velocity locking, i.e., directions of spin and group velocity are parallel or antiparallel depending on the chirality of the helix, and consequently, an almost perfect spin selectivity in a specific energy region in a wide range of the curvature and the torsion of the helix. We find that the present spin-velocity locking originates from the helical symmetry in which the Hamiltonian is invariant with respect to a combined operation of the rotation around the helix axis and the translation along the helix axis. Therefore, we expect that spin-velocity locking occurs in a wide variety of helical structures. [ABSTRACT FROM AUTHOR]

Protein mimics such as peptoids form self-assembled nanostructures whose shape and function are governed by the side chain chemistry and secondary structure. Experiments have shown that a peptoid sequence with a helical secondary structure assembles into microspheres that are stable under various conditions. The conformation and organization of the peptoids within the assemblies remains unknown and is elucidated in this study via a hybrid, bottom-up coarse-graining approach. The resultant coarse-grained (CG) model preserves the chemical and structural details that are critical for capturing the secondary structure of the peptoid. The CG model accurately captures the overall conformation and solvation of the peptoids in an aqueous solution. Furthermore, the model resolves the assembly of multiple peptoids into a hemispherical aggregate that is in qualitative agreement with the corresponding results from experiments. The mildly hydrophilic peptoid residues are placed along the curved interface of the aggregate. The composition of the residues on the exterior of the aggregate is determined by two conformations adopted by the peptoid chains. Hence, the CG model simultaneously captures sequence-specific features and the assembly of a large number of peptoids. This multiscale, multiresolution coarse-graining approach could help in predicting the organization and packing of other tunable oligomeric sequences of relevance to biomedicine and electronics. [ABSTRACT FROM AUTHOR]

The fundamental differences in phospholipids between bacterial and mammalian cell membranes present remarkable opportunities for antimicrobial design. However, it is challenging to distinguish bacterial anionic phospholipid phosphatidylglycerol (PG) from mammalian anionic phosphatidylserine (PS) with the same net charge. Here, we report a class of radially amphiphilic a helix antimicrobial peptides (RAPs) that can selectively discriminate PG from PS, relying on the helix structure. The representative RAP, L10-MMBen, can direct the rearrangement of PG vesicles into a lamellar structure with its helix axis parallel to the PG membrane surface. The helical structure imparts both the thermodynamic and kinetic advantages of L10-MMBen/PG assembly, and the hiding of hydrophobic regions in RAPs is crucial for PG recognition. L10-MMBen exhibits high selectivity against bacteria depending on PG recognition, showing low in vivo toxicity and significant treatment efficacy in mice infection models. Our study introduces a helicity-direct bacterial phospholipid recognition paradigm for designing highly selective antimicrobial peptides. [ABSTRACT FROM AUTHOR]

As an excellent class of electrode materials, carbon‐based materials have garnered sustained attention. Constructing carbon‐based skeleton with unique structure has become a vital research area in the fields of electrocatalysis. Recently, surface curvature has been extensive discussed as a compelling factor in electronic modulation for electrocatalyst design. Benefitting from its distinctive regulation, the intrinsic activity and service stability of catalysts during electrocatalytic process can be significantly improved. Therefore, a helical structure that adeptly integrates well‐regulated, highly ordered surface curvatures is considered to be of great research value for the synthesis of carbon‐based skeleton. In this Concept article, we systematically summarize the up‐to‐date reports on the synthetic methods of carbon‐based skeletons with helical structures and present major challenges in this field. We also emphasize that the helical carbon‐based skeleton could be combined with transition metals for cooperative coupling, potentially leading to the further development of high‐efficiency electrocatalysts. [ABSTRACT FROM AUTHOR]

Cellulose nanocrystal (CNC), as a typical natural photonic crystal material with outstanding advantages, has attracted increasing interests to develop stimulus‐responsive materials with vivid structural colors and circularly polarized light manipulators with high dissymmetry factors for widespread applications. However, limited by its spontaneous left‐handed cholesteric phase and absent right‐handed helical structure, current CNC‐based optical materials mainly achieve the selective reflection of left‐handed circularly polarized light (L‐CP) and the transmission of right‐handed circularly polarized light (R‐CP). Opposite to all reported intrinsic chirality in CNC assemblies, here first prominent twisted right‐handed helix in solid CNC film is found which is prepared through dynamically rotational self‐assembly. The dynamic rotation drives CNC particles to form a right‐handed helix with pitches of sub‐micron level regardless of rotary direction, realizing an ambidextrous reflection of both L‐CP and R‐CP for CNC film with maintained intrinsic structural color, and the first example of inversed right‐handed helix in CNC is further demonstrated. Moreover, the CNC films highly depend on the light propagation direction in term of apparent circular dichroism signals, presenting an exciting prospect for developing quantum transduction. This work is believed a breakthrough on chiral CNC photonic materials, providing new insights and application prospects for chiral CNC materials. [ABSTRACT FROM AUTHOR]

Many polypeptides form stable, helical secondary structures enabling the formation of lyotropic liquid crystalline (LLC) phases. Contrary to the well‐studied polyglutamate, their counterparts based on polyaspartates exhibit a much lower helix inversion barrier. Therefore, the helix sense is not solely dictated by the chirality of the amino acid used, but additionally by the nature and conformation of the polymer sidechain. In this work, polymers responsive to irradiation with visible light are designed achieving conformational transitions from helix‐to‐coil and helix‐to‐helix. The synthesis and the application as LLC mesogens of several (co‐)polyaspartates bearing ortho‐fluorinated azobenzene (FAB) as a photochromic group are presented. Many of the obtained polymers undergo changes in their secondary structure upon E‐Z‐isomerization of the FAB‐containing sidechain. Of special interest are copolymers that exhibit photo‐responsive helix inversion without loss of their helical secondary structure. These copolymers form stable LLC phases in helicogenic solvents, where the effect of photo‐switching on the macroscopic behavior is studied by NMR spectroscopy. Especially, the irradiation of the different LLC phases of the helix inversion polymers displays a change in the LLC order experienced by the solvent. These peculiar properties are promising for future applications as photo‐responsive alignment media for structure elucidation in NMR. [ABSTRACT FROM AUTHOR]

Under hydrothermal condition, lactate derivative (R)‐4‐(1‐ carboxyethoxy)‐2‐methylbenzoic acid ((R)‐H2cma) as chiral synthon assembled with 4,4′‐di(1H‐imidazol‐1‐yl)‐1,1′‐biphenyl (4,4'‐dib) and Ni(II) ions to obtain complex {[Ni2((R)‐cma)2(4,4'‐dib)2(H2O)] ⋅ 2H2O}n (HU20‐R). In complex HU20‐R, carboxyl group from lactate unit of (R)‐cma2− anion and coordinating H2O molecule adopt a μ2‐coordination mode to obtain dinuclear [Ni2(CO2)2(H2O)]2+ cluster. (R)‐cma2− anions and Ni(II) ions build single left‐handed (R)‐cma‐Ni‐chain, while 4,4'‐dib ligands are bridged by different Ni(II) centers to form double left‐handed 4,4'‐dib‐Ni‐chain. These helical secondary structures are further connected together to result in an 8‐connected 3D framework. PXRD tests indicated that complex HU20‐R has well hydro‐stability. UV‐vis absorption experiment confirmed that HU20‐R is a semi‐conducting material with strong absorption capacity for ultraviolet‐visible (UV‐vis) light. Additionally, electrochemical experiment revealed that HU20‐R has low impedance and high charge transport capacity. Further test results confirm that HU20‐R has noticeable photo‐catalytic effect in photodegradation of Rhodamine B (RhB) and antiferromagnetic property. [ABSTRACT FROM AUTHOR]

[Display omitted] Flexible light-emitting fibers and fabrics serve to bridge human–machine interactions. The desire for practical applications and the commercialization of flexible light-emitting fibers has accelerated structural progress and improvements. This review focuses on the structural design of light-emitting fibers and fabrics, starting with a summary of design principles, emission mechanisms, and structural evolution of coaxial structured light-emitting fibers. Subsequently, we explore recent advances in the helical structure design strategies that boost the mechanical sensitivity of light-emitting fibers. Following that, we analyze continuous preparation processes and the development of large-area intelligent light-emitting fabrics based on interwoven structures. Examples based on stiff and rigid inorganic-based light-emitting diodes integrated into flexible systems are also presented. Finally, we discuss the current challenges and future opportunities for light-emitting applications in the field of wearable and smart devices. [ABSTRACT FROM AUTHOR]

This paper primarily explores the modeling method of n-level complex helical structures with coal mining machine cables as the research object. The paper first elaborately introduces the modeling method of n-level helix curves based on parametric equations and coordinate transformations, and compensates for the n-level helix curves with corrected pitch, which can obtain more accurate n-level helix curves and improve the accuracy of n-level helix curves modeling. Subsequently, based on this high-precision n-level helix curves modeling method, the paper elaborates on the method of solving pitch and twisting radius of multi-layer helical structure. Calculation scripts were written based on the above methods, which can be used to batch calculate the twisting radius and pitch of each layer structure in multi-layer structures when satisfying the conditions of in-layer tangency, inter-layer tangency, and extrusion deformation, and retain the actual results through logical judgment. Then, based on the above two methods, the paper developed a modeling method for braided structures based on piecewise functions containing fifth-order polynomials, which can effectively avoid the problem of insufficiently dense arrangement of braided lines and easy interference in traditional methods. Finally, a set of modeling tools was developed using C# and Python in Grasshopper to implement the modeling algorithm. Taking the MCPT-1.9/3.3 3120 + 170 + 4 * 10 coal mining machine cable as an example. The cable was modeled using both the method proposed in this paper and the traditional method. Comparative data shows that the method proposed in this paper can reduce errors by 3.31E6 times in the second-level and above helical structures. In addition this paper compares the standard line length, measured line length, and the line length established by the proposed model, showing that the relative errors are both less than 0.1941%. This paper provides a new, systematic, high-precision, and full-process cable modeling method, in which all parameters except the process parameters are accurately solved by equations. It lays a theoretical foundation for the high-precision simulation and intelligent sensing cables, which is of great significance for improving the safety, stability, and efficient development of the coal mining industry. The research results of the paper can not only be applied to the modeling of coal mining machine cables but also can be extended to the modeling of other complex multi-layer helical structures. [ABSTRACT FROM AUTHOR]

In this work, a core‐substituted NMI‐conjugated dipeptide (4MNLV) was extensively studied in mixed solvent systems to explore the polarity effect on the self‐assembly pattern and their photophysical property. 4MNLV adopted J‐ or H‐ type aggregation pattern depending upon the polarity index of the solvent system chosen. The self‐assembly process was achieved through the anti‐solvent effect. UV‐vis study suggested that if the stock solution of 4MNLV was diluted with a relatively more polar solvent (compared to the stock solvent), then the system acquired J‐ type of aggregation pattern by showing a red‐shift in their absorption maxima (λmax). Conversely, when the stock was diluted by a relatively less polar solvent, H‐type of aggregation was observed, where blue shift of λmax was noticed. The emission spectra and the lifetime of the self‐assembled materials were also influenced by the chosen solvent system. The chirotopic behaviour of these self‐assembled materials was studied through CD spectroscopy. Morphological study indicated the formation of helical nanofibrillar structures. The bright green fluorescence of these highly biocompatible naphthalimide‐peptide conjugate was used for cell imaging application, indicating its futuristic scope. [ABSTRACT FROM AUTHOR]

A three-lobed helical pipe was installed downstream of the bend of a vertical-horizontal pneumatic pipeline. The swirl characteristics under different helical pipe structures were investigated. Results show that: (a) the maximum velocity region rotates quasiperiodically, and the smaller the pitch, the faster the rotation; (b) the 3D morphological changes of the axial velocity distribution in downstream sections are similar: from an arch to a pit and finally to a uniform flat top. The tangential velocity appears as a Rankine vortex near the wall; (c) the swirl decays rapidly along the downstream. The initial swirl intensity, proportional to the helical pipe length, increases first and then decreases with decreasing pitch, whereas the structural parameters have minimal effect on the swirl decay rate; (d) the helical tube remarkably increases the system energy consumption, and the total pressure drop is inversely proportional to the pitch and proportional to the length. [ABSTRACT FROM AUTHOR]

Inferior vena cava filter (IVCF) implantation is a common method of thrombus capture. By implanting a filter in the inferior vena cava (IVC), microemboli can be effectively blocked from entering the pulmonary circulation, thereby avoiding acute pulmonary embolism (PE). Inspired by the helical flow effect in the human arterial system, we propose a helical retrievable IVCF, which, due to the presence of a helical structure inducing a helical flow pattern of blood in the region near the IVCF, can effectively avoid the deposition of microemboli in the vicinity of the IVCF while promoting the cleavage of the captured thrombus clot. It also reduces the risk of IVCF dislodging and slipping in the vessel because its shape expands in the radial direction, allowing its distal end to fit closely to the IVC wall, and because its contact structure with the inner IVC wall is curved, increasing the contact area and reducing the risk of the vessel wall being punctured by the IVCF support structure. We used ANSYS 2023 software to conduct unidirectional fluid–structure coupling simulation of four different forms of IVCF, combined with microthrombus capture experiments in vitro, to explore the impact of these four forms of IVCF on blood flow patterns and to evaluate the risk of IVCF perforation and IVCF dislocation. It can be seen from the numerical simulation results that the helical structure does have the function of inducing blood flow to undergo helical flow dynamics, and the increase in wall shear stress (WSS) brought about by this function can improve the situation of thrombosis accumulation to a certain extent. Meanwhile, the placement of IVCF will change the flow state of blood flow and lead to the deformation of blood vessels. In in vitro experiments, we found that the density of the helical support rod is a key factor affecting the thrombus trapping efficiency, and in addition, the contact area between the IVCF and the vessel wall has a major influence on the risk of IVCF displacement. [ABSTRACT FROM AUTHOR]

We predicted the protein therapeutic targets specific to a Ru-based potential drug and its combination with pristine and N-doped carbon dot drug delivery systems, denoted as RuCN/CDs and RuCN/N-CDs. Synchrotron-based FTIR microspectroscopy (µFTIR) in addition to bioinformatics data on drug structures and protein sequences were applied to assess changes in the protein secondary structure of A2780 cancer cells. µFTIR revealed the moieties of the target proteins' secondary structure changes only after the treatment with RuCN and RuCN/N-CDs. A higher content of α-helices and a lower content of β-sheets appeared in A2780 cells after RuCN treatment. Treatment with RuCN/N-CDs caused a substantial increase in parallel β-sheet numbers, random coil content, and tyrosine residue numbers. The results obtained suggest that the mitochondrion-related proteins NDUFA1 and NDUFB5 are affected by RuCN either via overexpression or stabilisation of helical structures. RuCN/N-CDs either induce overexpression of the β-sheet-rich protein NDUFS1 and affect its random coil structure or interact and stabilise its structure via hydrogen bonding between -NH2 groups from N-CDs with protein C=O groups and –OH groups of serine, threonine, and tyrosine residues. The N-CD nanocarrier tunes this drug's action by directing it toward a specific protein target, changing this drug's coordination ability and inducing changes in the protein's secondary structures and function. [ABSTRACT FROM AUTHOR]

Here is described the synthesis and characterization of a stable hydrocarbon radical, peri‐benzo‐diindenotetracenyl, with a helical structure. Although the helical π‐radical has no peripheral substituents, it was stable in the solid and solutions. According to the X‐ray diffraction analysis and quantum chemical calculations, the radical was best described as an allyl radical fused by five Clar's sextets. The optically resolved enantiomers exhibited mirror image CD spectra with |gCD| of 2.4×10−4 at 522 nm. The racemization barrier was determined to be 95.9 kJ/mol at 298 K, which is compatible with that of [5]helicene (108 kJ/mol). [ABSTRACT FROM AUTHOR]

The formation of amyloid fibrils is a common feature of many protein systems. It has implications in both health, as amyloid fibrils are implicated in over 30 degenerative diseases, and in the biological functions of proteins. Surfaces have long been known to affect the formation of fibrils but the specific effect depends on the details of both the surface and protein. Fully understanding the role of surfaces in fibrillization requires microscopic information on protein conformation on surfaces. In this paper replica exchange molecular dynamics simulation is used to investigate the model fibril forming protein, A β (10–40) (a 31-residue segment of the amyloid-beta protein) on surfaces of different hydrophobicity. Similar to other proteins A β (10–40) is found to adsorb strongly onto hydrophobic surfaces. It also adopts significantly different sets of conformations on hydrophobic and polar surfaces, as well as in bulk solution. On hydrophobic surfaces, it adopts partially helical structures, with the helices overlapping with beta-strand regions in the mature fibril. These may be helical intermediates on the fibril formation pathway, suggesting a mechanism for the enhanced fibril formation seen on hydrophobic surfaces. [ABSTRACT FROM AUTHOR]

Helical baffle heat exchanger has a wide application in many industrial fields because of its high efficiency and low resistance. A new structure of the grooved helical baffle is proposed to strengthen the stability between the overlapped baffles during the spiral flow of fluid. Based on this structure, the liquid water was selected as the working medium in the tube side and shell side, the flow field characteristics and heat transfer performances of the quadrant helical baffle heat exchanger are numerically analyzed using software FLUENT 2017. The results show that when the helical angle is large (50°) and the overlapped amount is small (0.5), the comprehensive performance of the heat exchanger is the best. Therefore, the heat exchanger performance can be improved by choosing the appropriate combination of helical angle and overlapped amount. The correlation formula of the shell side heat transfer coefficient with helical angle, overlapped amount and mass flow rate is obtained by means of regression analysis, which can provide a reference for engineering application and optimal design of grooved helical baffle heat exchanger. [ABSTRACT FROM AUTHOR]

A sol-gel method was employed to synthesize phase-pure (1-x)BiFeO3-xBi(Mn0.5Ti0.5)O3 (abbreviated as BFO-xBMT, x = 0–0.10) multiferroic ferrites. The investigation focused on the structure, optical, and magnetic properties, and their dependence on composition. X-ray diffraction analysis (XRD) revealed a single phase rhombohedral structure for BiFeO3 (BFO), with distinct double peaks (104)/(110) and (006)/(202) at diffraction angles 2θ ∼ 32.0° and 39.5°. As the content of Bi(Mn0.5Ti0.5)O3 (BMT) increased, a structural transition from rhombohedral (R3c) to pseudo-cubic (Pm3m) phase was observed. Doping with BMT led to a decrease in particle size. The band gap (Eg) of BFO-xBMT materials exhibited a slight increase from 1.99 eV in BFO to 2.18 eV in the BFO-0.10BMT composition. The introduction of BMT resulted in a significantly enhanced room temperature ferromagnetism in BiFeO3, with the maximum magnetic moment doubling to around 5.7 emu/g for the BFO-0.04BMT solid solution. This improvement is attributed to the addition of BMT inducing intrinsic strain in the crystal lattice, suppressing the intrinsic helical spin structure of BFO, and thus enhancing its latent magnetic potential. The research demonstrated the substantial influence of BMT perovskite on the structure, optical, and magnetic properties of BFO materials. Overall, the results suggest that the BFO-xBMT multiferroic ferrites with optimal composition hold promise for use in multifunctional devices. [ABSTRACT FROM AUTHOR]