Use Of Structures Research Articles

Manipulating electron redistribution induced by asymmetric coordination for electrocatalytic water oxidation at a high current density

Electronic structure manipulation with regard to active site coordination is an effective strategy to improve the electrocatalytic oxygen evolution reaction (OER) activity. Herein, we present the structure–activity relationship between oxygen-atom-mediated electron rearrangement and active site coordination asymmetry. Ni2+ ions are introduced to FeWO4 on Ni foam (NF) via self-substitution to break the symmetry of the FeO6 octahedron and regulate d-electron structure of Fe sites. Structural regulation optimizes the adsorption energy of hydroxyl on the Fe sites and promotes the partial formation of hydroxyl oxide with high OER activity on the tungstate surface. Fe0.53Ni0.47WO4/NF with the asymmetric FeO6 octahedron of Fe sites can achieve an ultralow overpotential of 170 mV at 10 mA cm−2 and 240 mV at 1000 mA cm−2 with robust stability for 500 h at high current density under alkaline conditions. This research develops novel electrocatalysts with impressive OER performance and provides new insights into the design of highly active catalytic systems.

High-performance flexible nanogenerators based on piezoelectric hBN- induced polyvinylidene fluoride nanofibers

Flexible piezoelectric nanogenerators (PENGs) are promising candidates for clean energy harvesting and powering electronics, especially for low-power modules. In this study, a PENG has been fabricated by incorporating functionalized mono-/few-layered hexagonal boron nitride nanosheets (F-hBNNS) in a polyvinylidene fluoride (PVDF) polymeric matrix. The synthesized 2D nanosheets are well characterized using different spectroscopic and microscopic methods. The analysis showed successful exfoliation of hBN, which indicated less than three layers of hBN after exfoliation and sulfonated and carboxylated functionalization on the surface. Also, the piezoresponse force microscopy (PFM) tests revealed a 3 times higher piezoelectric coefficient for F-hBNNS compared to that of the non-functionalized hBN with the same number of layers. The synthesized F-hBNNS with piezo-flexoelectric properties boosted the energy harvesting performance of the electrospun PVDF-based fibrous mats 5.5 times. The open-circuit output voltage test showed 23 V at 4 Hz with a power density of 1.93 μW/cm2 at a resistance loading of 16 MΩ in a simple finger tapping. The fabricated PENGs showed no decline in voltage output over 1000 cycles of bending-unbending of a robotic finger. It is proposed that the enhanced performance is due to (i) the synergistic effects of the flexoelectric and piezoelectric properties of synthesized F-hBNNS in the PVDF matrix and (ii) the manipulation of the crystalline structure of the PVDF chains, which is increased to 90% β-phase crystallinity with 49.03% total degree of crystallinity. This study shows the compatibility of the fabricated PENGs with the human body's biomechanics for being used as an efficient energy source for wearable devices with low power consumption.

A Fault-Tolerant Soft Swallowing Robot Capable of Grasping Delicate Structures Underwater

To improve the manipulation efficiency and robustness of soft grippers, this work proposes a soft swallowing robot with a continuous grasping mode. The soft swallowing robot has two advantages of grasping fault tolerance and structural fault tolerance: i) It can perform the grasping action uninterruptedly to deal with non-cooperative objects efficiently, unlike most existing grippers, which must perform the release action after grasping failure to carry out the next grasping action; ii) It can still maintain the grasping function after the failure of a part of its core structures. The finite element model quantitatively characterizes the effects of object size, friction coefficient, and manufacturing materials on the swallowing force. The fault tolerance experiments prove that the maximum proportion of structural faults that the soft swallowing robot can tolerate is 50%. In addition, the grasping experiments for underwater animals demonstrated that the soft swallowing robot has the advantages of high efficiency and strong adaptability in the manipulation of delicate structures. The research results are expected to be applied to underwater biological sample collection and seafood fishing.

Recent Progress on Structure Manipulation of Poly(vinylidene fluoride)‐Based Ferroelectric Polymers for Enhanced Piezoelectricity and Applications

AbstractPoly(vinylidene fluoride) (PVDF)‐based polymers demonstrate great potential for applications in flexible and wearable electronics but show low piezoelectric coefficients (e.g., −d33 < 30 pC N−1). The effective improvement for the piezoelectricity of PVDF is achieved by manipulating its semicrystalline structures. However, there is still a debate about which component is the primary contributor to piezoelectricity. Therefore, current methods to improve the piezoelectricity of PVDF can be classified into modulations of the amorphous phase, the crystalline region, and the crystalline–amorphous interface. Here, the basic principles and measurements of piezoelectric coefficients for soft polymers are first discussed. Then, three different categories of structural modulations are reviewed. In each category, the physical understanding and strategies to improve the piezoelectric performance of PVDF are discussed. In particular, the crucial role of the oriented amorphous fraction at the crystalline–amorphous interface in determining the piezoelectricity of PVDF is emphasized. At last, the future development of high performance piezoelectric polymers is outlooked.

Controllable synthesis of bifunctional magnetic carbon dots for rapid fluorescent detection and reversible removal of Hg2+

Mercury is one of the most toxic heavy metals, whose identification and separation are crucial for environmental remediation. Till now, it remains a significant challenge upon simultaneous detection and removal of Hg2+. Herein, bifunctional probe magnetic carbon dots were synthesized and optimized via systematic structure manipulation of the carbon and iron precursors towards fluorescence, Hg2+ adsorption and magnetic separation. The probe exhibited blue emission at 440 nm with high quantum yield of 55 % and a high paramagnetism with the saturation magnetization value of 22.70 emu/g. Furthermore, the fluorescent detection of Hg2+ with limit of 5.40 nM and high selectivity were achieved through surface structure manipulation with moderate -NH2, -SH and Fe contents. As a result, the magnetic removal of Hg2+ was consecutively effectuated with high removal efficiency of 98.30 %. The detection and recovery of Hg2+ in real samples were further verified and demonstrated the excellent environmental tolerance of probe. The reusability was viable with recycling at least three turns by external magnet. This work not only provides a promising approach for simultaneous detection and removal of heavy metal pollution, but also provides an excellent example as a versatile platform for multifunction integration via the structure manipulation for other applications.

Hybrid Exoscopic and Robotic Transoral Removal of a Bilateral Hilar Submandibular Stone: Technical Note and Review of the Literature

Submandibular gland sialolithiasis can be addressed by gland removal or by stone removal. Intraoral stone removal has now become the go-to technique to minimize aesthetic and functional sequelae (e.g., marginalis mandibulae injury, visible surgery scar) and, although traditional techniques were first experimented with (intraoral ducotomy), newer techniques drew the interest of the scientific community: sialoendoscopy, TORS-S (TransOral Robotic Surgery Assisted–Sialolithotomy) and VITOM-guided sialolithotomy. In this article, we compare the two newest transoral techniques for transoral sialolithotomy, TORS-S and 3D-4K VITOM-guided sialolithotomy, used to treat bilateral hilar submandibular gland sialolithiasis in the same patient, one technique for each side. Using these techniques, a faster recovery is achievable with almost no anatomical and/or functional sequelae, since they both allow better visualization and manipulation of soft tissues and noble structures (e.g., lingual nerve and Wharton’s duct) and make surgery easier and safer. Moreover, OR staff can better perceive surgical steps and be involved in the procedure, thus showing the high educational and training potential of these technologies.

Tuning crystal orientation and chiral spin order in Mn3Ge by annealing process and ion implantation

The non-collinear antiferromagnetic Weyl semimetal Mn3X (X = Ga, Ge, Sn) system has attracted a lot of attentions owing to its robust anomalous Hall effect (AHE), large spin Hall angle and small net magnetization at room temperature. The high spin-charge interconversion efficiency makes it a super candidate in topological antiferromagnetic spintronic devices, which could facilitate ultra-fast operation of high-density devices with low energy consumption. In this work, we have realized to obtain different chiral spin structures in Heusler alloy Mn3Ge thin films, which originate from different crystalline orientations. The high-quality (0002)- and (200)-oriented single phase hexagonal Mn3Ge films are achieved by controllable growth, annealing process and ion implantation. The various magnetic properties and AHE behaviors are observed along a and c crystal axes, equivalent to magnetic field in and out of the inverse triangular spin plane. The observation demonstrates the manipulation of crystal structure accompanied with chiral spin order in a non-collinear antiferromagnetic Mn3Ge film, which is induced by energy conversion and defect introduction. The in situ thermal treatment induces crystal phase rotation up to 90° and robust AHE modulation, which is significantly important and highly desirable for flexible spin memory device applications.

Cellulose‐based Interfacial Solar Evaporators: Structural Regulation and Performance Manipulation

AbstractThe shortage of freshwater resources has become a major obstacle threatening human development, and directly utilizing solar energy by solar evaporators is emerging as a promising method to produce freshwater from the seawater. Compared to many synthetic polymer‐based evaporators, cellulose‐based evaporators are expected to offer more interesting features benefiting from the renewable feature and abundant reserves of cellulose‐contained naturally occurring materials. First, according to the different fabrication methods, cellulose‐based solar evaporators can be divided into two types, i.e., top‐down utilization (wood‐based) and bottom‐up assembled (cellulose composite‐based), respectively. The different fabrication schemes also bring their own unique advantages, such as the bimodal porous structure of wood‐based evaporators and the artificial interconnection microporous network of cellulose composite‐based evaporators. Subsequently, this review further summarizes the most recent advances and highlights of those cellulose‐based solar evaporators, by focusing on their structural regulation strategies (e.g., drilled channel array, asymmetric wettability structure, delignification, 2D waterway, etc.) and evaporation performance improvements (e.g., salt resistance, high evaporation rate, etc.). Finally, the challenges in this field and potential solutions are also discussed, which are anticipated to provide new opportunities toward the future development of cellulose and other kinds of biomass‐based evaporators.

ОПРЕДЕЛЕНИЕ ИНДЕКСА УПРАВЛЯЕМОСТИ И ВЫЯВЛЕНИЕ ОСОБЫХ ПОЛОЖЕНИЙ ПАРАЛЛЕЛЬНОГО МАНИПУЛЯТОРА

The article presents a model, tools, methodology and results of identifying special provisions when planning the movement of a parallel manipulator such as the Gough-Stewart platform. Special positions are understood as positions having geometric uncertainty, singularity. Singular positions are estimated by analyzing the Jacobian matrix using its singular value decomposition. The calculation of the Jacobi matrix and its singular values is performed using special libraries of the high-level Python programming language. The presence of special positions in the workspace is analyzed using the dexterity index, which characterizes the ratios of the singular values of the singular value decomposition of the Jacobian matrix. A series of computational experiments are carried out to calculate the dexterity index, identify and analyze special positions in the working area. The results of a computational experiment for various design versions of the platform, which differ in the ratio of the radii of the movable platform and the fixed base, are presented. The analysis of the characteristic features of the formation of singularity zones in their working zones is carried out and design options are identified that have the maximum dexterity index of the working area. The presented approach is applicable in the framework of the development, modernization, optimization of structural elements of parallel structure manipulators.

After the Knife: A Detailed Roadmap for Vestibular Schwannoma Resection in the Semi-Sitting Position – How I do it

Vestibular schwannoma surgery remains a neurosurgical challenge, with known risks, dependent on a number of factors, from patient selection to surgical experience of the team. The semi-sitting position has gained popularity as an alternative to the traditional supine position for vestibular schwannoma resection due to potential advantages such as improved surgical exposure due to clearer surgical field and anatomical orientation. However, there is a lack of standardized protocols for performing the procedure in the semi-sitting position, leading to variations in surgical techniques and outcomes. In this study, we aimed to establish a standardized approach for vestibular schwannoma resection using the semi-sitting position. Initiating after final position for semi-sitting, the authors have divided the surgical steps into five major parts for improved understanding and replication. Surgical techniques were analyzed through one hundred steps to identify commonalities, determining the optimal procedural steps for the semi-sitting position using surgical video for visual conceptualization. The analysis described one hundred steps for vestibular schwannoma resection in the semi-sitting position, with visual demonstration of the various parts of the procedure through surgical videos. Specific recommendations for each step were outlined, including appropriate approach, monitoring strategies, and tumor and posterior fossa structures manipulation. Five major parts of the procedure were identified, leading to a reproducible standardization of the surgical procedure of vestibular schwannoma resection in the semi-sitting position. This study provides a comprehensive standardized protocol for the semi-sitting procedure in vestibular schwannoma resection. By establishing a consistent approach, surgeons can minimize variations in surgical techniques and improve patient outcomes. The identified steps and recommendations can serve as a valuable resource for surgical teams involved in vestibular schwannoma resection and facilitate the dissemination and reproducibility of best practices.

Structural Manipulations of Marine Natural Products Inspire a New Library of 3-Amino-1,2,4-Triazine PDK Inhibitors Endowed with Antitumor Activity in Pancreatic Ductal Adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) is one of the main aggressive types of cancer, characterized by late prognosis and drug resistance. Among the main factors sustaining PDAC progression, the alteration of cell metabolism has emerged to have a key role in PDAC cell proliferation, invasion, and resistance to standard chemotherapeutic agents. Taking into account all these factors and the urgency in evaluating novel options to treat PDAC, in the present work we reported the synthesis of a new series of indolyl-7-azaindolyl triazine compounds inspired by marine bis-indolyl alkaloids. We first assessed the ability of the new triazine compounds to inhibit the enzymatic activity of pyruvate dehydrogenase kinases (PDKs). The results showed that most of derivatives totally inhibit PDK1 and PDK4. Molecular docking analysis was executed to predict the possible binding mode of these derivatives using ligand-based homology modeling technique. Evaluation of the capability of new triazines to inhibit the cell growth in 2D and 3D KRAS-wild-type (BxPC-3) and KRAS-mutant (PSN-1) PDAC cell line, was carried out. The results showed the capacity of the new derivatives to reduce cell growth with a major selectivity against KRAS-mutant PDAC PSN-1 on both cell models. These data demonstrated that the new triazine derivatives target PDK1 enzymatic activity and exhibit cytotoxic effects on 2D and 3D PDAC cell models, thus encouraging further structure manipulation for analogs development against PDAC.

Manipulation of the Structure and Optoelectronic Properties through Bromine Inclusion in a Layered Lead Bromide Perovskite.

One of the great advantages of organic-inorganic metal halides is that their structures and properties are highly tuneable and this is important when optimizing materials for photovoltaics or other optoelectronic devices. One of the most common and effective ways of tuning the electronic structure is through anion substitution. Here, we report the inclusion of bromine into the layered perovskite [H3N(CH2)6NH3]PbBr4 to form [H3N(CH2)6NH3]PbBr4·Br2, which contains molecular bromine (Br2) intercalated between the layers of corner-sharing PbBr6 octahedra. Bromine intercalation in [H3N(CH2)6NH3]PbBr4·Br2 results in a decrease in the band gap of 0.85 eV and induces a structural transition from a Ruddlesden-Popper-like to Dion-Jacobson-like phase, while also changing the conformation of the amine. Electronic structure calculations show that Br2 intercalation is accompanied by the formation of a new band in the electronic structure and a significant decrease in the effective masses of around two orders of magnitude. This is backed up by our resistivity measurements that show that [H3N(CH2)6NH3]PbBr4·Br2 has a resistivity value of one order of magnitude lower than [H3N(CH2)6NH3]PbBr4, suggesting that bromine inclusion significantly increases the mobility and/or carrier concentration in the material. This work highlights the possibility of using molecular inclusion as an alternative tool to tune the electronic properties of layered organic-inorganic perovskites, while also being the first example of molecular bromine inclusion in a layered lead halide perovskite. By using a combination of crystallography and computation, we show that the key to this manipulation of the electronic structure is the formation of halogen bonds between the Br2 and Br in the [PbBr4]∞ layers, which is likely to have important effects in a range of organic-inorganic metal halides.

N-substituted tetrahydro-beta-carboline as mu-opioid receptors ligands: in silico study; molecular docking, ADMET and molecular dynamics approach.

Manipulating intracellular signals by interaction with transmembranal G-protein-coupled receptors (GPCRs) is the way of action of more than 30% of available medicines. Designing molecules against GPCRs is most challenging due to their flexible binding orthosteric and allosteric pockets, a property that lead to different mode and extent of activation of intracellular mediators. Here, in the current study we aimed to design N-substituted tetrahydro-beta-carbolines (THβC's) targeting Mu Opioid Receptors (MORs). We performed ligand docking study for reference and designed compounds against active and inactive states of MOR, as well as the active state bound to intracellular mediator of Gi. The reference compounds include 40 known agonists and antagonists, while the designed compounds include 25,227 N-substituted THβC analogues. Out of the designed compounds, 15 compounds were comparatively having better extra precision (XP) Gscore and were analyzed for absorption, distribution, metabolism, and excretion-toxicity (ADMET) properties, drug-likness, and molecular dynamic (MD) simulation. The results showed that N-substituted tetrahydro-beta-carbolines with and without C6-methoxy group substitutions (THBC/6MTHBC) analogues of A1/B1 and A9/B9 have relatively acceptable affinity and within pocket-stability toward MOR compared to the reference compounds of morphine (agonist) and naloxone (antagonist). Moreover, the designed analogues interact with key residue within the binding pocket of Asp 147 that is reported to be involved in receptor activation. In conclusion, the designed THBC analogues represent a good starting point for designing opioid receptor ligands other than morphinan scaffold, that have good synthetic accessibility which promotes feasible structural manipulation to tailor pharmacological effects with minimal side effects.

Efficient structural manipulation of PbS in Er-doped silica optical fibers for enhanced amplification systems

In active silica optical fibers, improving the solubility and uniformity of non-concentration-quenching luminescence centers is a key strategy to achieve high gain fiber amplifiers. Herein, we report a novel Er-doped silica optical fiber (EDF) modified by PbS semiconductor incorporation for the first time. Owing to the bridge role of PbS, Er2O3 nanofilms deposited on the substrate via atomic layer deposition (ALD) have porous and loosely layered network structures with an increasing number of ALD-PbS layers. Subsequently, during the high-temperature fiber preparation process, this loose porous structure aids the dissolution and provides an optimal local environment of Er3+ ions in the silica matrix. As a result, the maximum phonon energy of the silica network for PbS/Er co-doped silica optical fiber (PEDF) is reduced, resulting in an increase of the Er3+ ion fluorescence lifetime, approximately 11.455 ms. Furthermore, we achieved 34 dB maximum gain of PEDF sample with the lowest noise figure of 3.9 dB at 1.5 μm. The gain bandwidth over 20 dB of PEDF is approximately 46 nm, which is nearly 44% higher than that of EDF. These results indicate that the PEDF prepared by structural manipulation has great potentials in optical fiber amplifier and laser applications.

Layer symmetry and interlayer engineering of birnessites towards high-performance rechargeable aqueous Zn-MnO2 batteries

Rechargeable aqueous Zn-MnO2 batteries are promising candidates for large-scale energy storage systems, yet still plagued by the phase transition and structural collapse issues of MnO2 cathodes during cycling. Interlayer intercalation for the layered MnO2 turns out to be a viable alternative and become the mainstream structure design strategy. However, the characteristics of Mn octahedral layers are generally neglected. Herein, for the first time we elucidate apart from interlayer ions, how layer symmetry of birnessites exerts on the electrochemical performance. The Mn(II) ions stabilized hexagonal birnessite exhibits elevated charge storage performance than its monoclinic precursor, attributing to the layer cation vacancies generated after symmetry transformation, interlayer Mn(II) ions and nanosized morphology. A high specific capacity of 279 mAh g−1 at 1 C is achieved, as well as an outstanding long-term cycling stability with 97% retention over 8000 cycles. The reaction mechanism is comprehensively illustrated. This work previews a new gateway for the design of high-performance layered cathode materials by synergistic manipulation of the crystal structure of the layers and the interlayer environment.

Recent Advances in Protein-Specific Glycan Imaging and Editing.

Glycosylation in live cell and animal modulate a constellation of biological functions. The advent of Chemical Biology has revolutionized the analysis and tailoring of glycans, by introducing myriads of glycan engineering methods. However, the ideal scenario to achieve glycan monitoring and structural manipulation at any hierarchical levels is unmet yet. Herein we review recent advances in the methodological innovation and the versatile applications of the protein-specific glycan visualization and editing in deciphering the biological functions of glycans. An outlook for future directions toward specific sugar-chain editing is also included.

Assisting in Microsurgery: Operative and Technical Considerations

Microsurgery is technically challenging, typically requiring a primary surgeon and an assistant to complete several key operative steps. These may include manipulation of fine structures, such as nerves or vessels in preparation for anastomosis; stabilization of the structures; and needle driving. Even seemingly mundane tasks of suture cutting and knot tying require fine coordination between the primary surgeon and assistant in the microsurgical environment. Although prior literature discusses the implementation of microsurgical training centers at academic institutions and residency programs, there is a paucity of work describing the role of the assistant surgeon in a microsurgery operation. In this surgical technique article, the authors discuss the role of the assisting surgeon in microsurgery, with recommendations for trainees and attendings alike.

Feasibility of extended transforaminal approach (medial subchoroid) for resection of a benign aqueductal tumor in a patient with type 1 neurofibromatosis

The extended transforaminal endoscopic approach allows visualization and manipulation of the third ventricle posterior structures in a safe and comfortable manner. The medial subchoroidal approach has been described as a feasible alternative to the classical transchoroidal approach. In this video, the authors present the case of a 14-year-old male with a history of neurofibromatosis type 1 who was referred to our department after presenting with headaches and diplopia for 2 weeks. Suspecting an aqueduct tumor, the authors performed an endoscopic surgical procedure through a single approach with third cisternostomy and resection of the tumor that produced the stenosis. The video can be found here: https://stream.cadmore.media/r10.3171/2023.1.FOCVID22155.

An expandable chamber for safe brain retraction: new technologies in the field of transcranial endoscopic surgery.

Neurosurgery is a highly specialized field: it often involves surgical manipulation of noble structures and cerebral retraction is frequently necessary to reach deep-seated brain lesions. There are still no reliable methods preventing possible retraction complications. The objective of this study was to design work chambers well suited for transcranial endoscopic surgery while providing safe retraction of the surrounding brain tissue. The chamber is designed to be inserted close to the intracranial point of interest; once it is best placed it can be opened. This should guarantee an appreciable workspace similar to that of current neurosurgical procedures. The experimental aspect of this study involved the use of a force sensor to evaluate the pressures exerted on the brain tissue during the retraction phase. Following pterional craniotomy, pressure measurements were made during retraction with the use of a conventional metal spatula with different inclinations. Note that, although the force values necessary for retraction and exerted on the spatula by the neurosurgeon are the same, the local pressure exerted on the parenchyma at the edge of the spatula at different inclinations varied greatly. A new method of cerebral retraction using a chamber retractor (CR) has been designed to avoid any type of complication due to spatula edge overpressures and to maintain acceptable pressure values exerted on the parenchyma.

Submerged Macrophyte Restoration in Enclosure: A Proper Way for Ecological Remediation of Shallow Lakes?

Degradation of lake ecosystem is a common problem existing in many countries. Remediation of degraded lake is urgently needed in order to maintain water safety and lake ecosystem health. Restoration of submerged macrophyte is considered as an important measure of ecological remediation of shallow lakes after pollution loading get effectively controlled. Nowadays, enclosures resembling those used in aquaculture historically are widely used for submerged macrophyte restoration. Although submerged macrophyte can be successfully restored in enclosure, it’s contribution to the whole lake ecological remediation is limited. Fish manipulation, which reduces fish stock and adjusts fish community structure, was found able to improve water quality and promote submerged macrophyte restoration in many lakes. However, the role of fish in ecological restoration do not receive enough attention in many ecological remediation projects. Future studies are required to better understand the role of fish in lake nutrient cycle and the influence on submerged macrophyte to help develop theory that better guide the fish manipulation for the ecological remediation in shallow lakes. In the end, we want to point out that manipulation of fish community structure following by natural restoration and/or artificial planting of submerged macrophyte could be an effective strategy for whole lake ecological remediation of shallow lakes, and suggest that fish manipulation measure should be tested in more ecological remediation projects of shallow lakes worldwide.