Unique Class Research Articles

Structural insights into the convergent evolution of sulfoxide synthase EgtB-IV, an ergothioneine-biosynthetic homolog of ovothiol synthase OvoA.

Non-heme iron-dependent sulfoxide/selenoxide synthases (NHISS) constitute a unique metalloenzyme class capable of installing a C-S/Se bond onto histidine to generate thio/selenoimidazole antioxidants, such as ergothioneine and ovothiol. These natural products are increasingly recognized for their health benefits. Among associated ergothioneine-biosynthetic enzymes, type IV EgtBs stand out, as they exhibit low sequence similarity with other EgtB subfamilies due to their recent divergence from the ovothiol-biosynthetic enzyme OvoA. Herein, we present crystal structures of two representative EgtB-IV enzymes, offering insights into the basis for this evolutionary convergence and enhancing our understanding of NHISS active site organization more broadly. The ability to interpret how key residues modulate substrate specificity and regioselectivity has implications for downstream identification of divergent reactivity within the NHISS family. To this end, we identify a previously unclassified clade of OvoA-like enzymes with a seemingly hybrid set of characteristics, suggesting they may represent an evolutionary intermediate between OvoA and EgtB-IV.

A Review on Chemical Structures and Biological Activities of Dopamine Derivatives from Medicinal Insects.

Medicinal insects play an important role in the treatment of refractory diseases due to their unique and rich pharmacological activities. However, compared to plants, microorganisms, and marine organisms, medicinal insects have been largely ignored. Some small molecules isolated from insects are known to have defensive effects, but their majority roles remain unknown. In-depth research on the small molecules of medicinal insects has been conducted in recent years. Then alkaloids, dopamine derivatives, nucleoside derivatives, and other components are obtained. Among them, dopamine derivatives are a unique class of components from medicinal insects. Thus, we present a comprehensive overview of chemical structures and biological activities of dopamine derivatives from some medicinal insects, which will bring more attention to other researchers for further chemical and biological investigations on the unique dopamine derivatives as well as medicinal insects.

The Chemical Puzzle of Weak G-Band Stars: A Comprehensive Study of HD 54627, HD 105783, HD 198718, and HD 201557

Weak G-band stars (WGBs) are a unique class of objects characterized by weak CH molecular lines in the Fraunhofer G band, indicative of a deficiency in 12C. This peculiar spectral feature is often accompanied by significant enrichments in N and, occasionally, Li and Na abundances. Despite their rarity and recent discoveries of new WGB candidates, the underlying formation mechanism of these stars remains unknown. In this study, we present a comprehensive chemical analysis of four neglected WGBs: HD 54627, HD 105783, HD 198718, and HD 201557. These stars, though identified as WGBs, have been poorly studied to date. Our analysis utilizes high-resolution échelle spectra with a power resolution of R ≈ 48,000, complemented by photometric and astrometric data from the literature. Applying the local thermodynamic equilibrium (LTE) approximation we determine the chemical abundance and then we conduct posterior non-LTE (NLTE) corrections for specific chemical abundances, including Li, O, Na, and Mg. Additionally, we provide details on the projected rotational velocities ( vsini ) and conduct a thorough investigation of the kinematics and orbits of our sample, comparing them with other well-studied WGBs reported in the literature. Our findings indicate that these stars originate from the thin disk, as evidenced by the absence of alpha-element enrichment and kinematics. Notably, half of the WGBs in our sample exhibit Li-rich characteristics, and we identify no rapid rotators ( vsini> 8.0 km s−1) or infrared excess among our studied stars.

Self-Healing Materials for Bioelectronic Devices.

Though the history of self-healing materials stretches far back to the mid-20th century, it is only in recent years where such unique classes of materials have begun to find use in bioelectronics-itself a burgeoning area of research. Inspired by the natural ability of biological tissue to self-repair, self-healing materials play a multifaceted role in the context of soft, wireless bioelectronic systems, in that they can not only serve as a protective outer shell or substrate for the internal electronic circuitry-analogous to the mechanical barrier that skin provides for the human body-but also, and most importantly, act as an active sensing safeguard against mechanical damage to preserve device functionality and enhance overall durability. This perspective presents the historical overview, general design principles, recent developments, and future outlook of self-healing materials for bioelectronic devices, which integrates topics in many research disciplines-from materials science and chemistry to electronics and bioengineering-together.

From Ancient Practices to Modern Science: A Review on the Synthesis and Characterization of Ayurvedic Bhasmas

Ayurvedic Bhasma, an ancient form of Indian traditional medicine, represents a unique class of herbo-mineral formulations prepared through a meticulous process involving calcination. This review provides a comprehensive synthesis and characterization of Ayurvedic Bhasmas, focusing on its preparation methods, physicochemical properties, and characterization. The synthesis of Bhasma involves a series of Shodhana (purification), Marana (incineration), and Bhavana (soaking and drying) processes, each contributing to the transformation of raw minerals and herbs into bioavailable nanoparticles with enhanced efficacy and reduced toxicity. The review delves into the intricate processes involved in the production of various bhasmas, prepared in our laboratory as well as reports by other researchers. It also highlights modern scientific techniques used to characterize these formulations, including XRD, SEM, TEM, FTIR, AAS, NAA, DLS etc. These techniques reveal the nanoscale size, crystalline structure, and elemental composition of bhasmas, providing insights into their therapeutic potential and safety profiles.

Exploring a unique class of flavoenzymes: Identification and biochemical characterization of ribosomal RNA dihydrouridine synthase

Dihydrouridine (D), a prevalent and evolutionarily conserved base in the transcriptome, primarily resides in tRNAs and, to a lesser extent, in mRNAs. Notably, this modification is found at position 2449 in the Escherichia coli 23S rRNA, strategically positioned near the ribosome's peptidyl transferase site. Despite the prior identification, in E. coli genome, of three dihydrouridine synthases (DUS), a set of NADPH and FMN-dependent enzymes known for introducing D in tRNAs and mRNAs, characterization of the enzyme responsible for D2449 deposition has remained elusive. This study introduces a rapid method for detecting D in rRNA, involving reverse transcriptase-blockage at the rhodamine-labeled D2449 site, followed by PCR amplification (RhoRT-PCR). Through analysis of rRNA from diverse E. coli strains, harboring chromosomal or single-gene deletions, we pinpoint the yhiN gene as the ribosomal dihydrouridine synthase, now designated as RdsA. Biochemical characterizations uncovered RdsA as a unique class of flavoenzymes, dependent on FAD and NADH, with a complex structural topology. In vitro assays demonstrated that RdsA dihydrouridylates a short rRNA transcript mimicking the local structure of the peptidyl transferase site. This suggests an early introduction of this modification before ribosome assembly. Phylogenetic studies unveiled the widespread distribution of the yhiN gene in the bacterial kingdom, emphasizing the conservation of rRNA dihydrouridylation. In a broader context, these findings underscore nature's preference for utilizing reduced flavin in the reduction of uridines and their derivatives.

Metal nanoparticles loaded polyurethane nano-composites and their catalytic/antimicrobial applications: a critical review

Abstract Polyurethane (PU) belongs to a unique class of polymers. Different properties of PU such as mechanical strength and biocompatibility can be enhanced by co-polymerizing it with different bio and synthetic polymers. It finds huge applications as micro-reactors for the fabrication of metal nanoparticles (MNPs) owing to the synergistic properties of both polyurethane and fabricated metal nanoparticles. Metal nanoparticles fabricated polyurethane have gained much attention in the last few years. These types of nanocomposites hyphenate the mechanical properties of polyurethane with the high surface-to-volume ratio of metal nanoparticles. Here, this review article briefly evaluates different methods of synthesis of polyurethane-based metal nanocomposites and their characterization via different techniques to evaluate their properties. Applications of these polyurethane based nanocomposite materials have also been described critically in different fields depending upon their catalytic, antimicrobial and antifungal potential. Future directions of these nanocomposite materials have also been described in the field of designing of nano-filters and nano-devices in order to attain environmental remediation and sustainability.

Expression of Iron Metabolism Genes Is Potentially Regulated by DOF Transcription Factors in Dendrocalamus latiflorus Leaves.

Transcription factors (TFs) are crucial pre-transcriptional regulatory mechanisms that can modulate the expression of downstream genes by binding to their promoter regions. DOF (DNA binding with One Finger) proteins are a unique class of TFs with extensive roles in plant growth and development. Our previous research indicated that iron content varies among bamboo leaves of different colors. However, to our knowledge, genes related to iron metabolism pathways in bamboo species have not yet been studied. Therefore, in the current study, we identified iron metabolism related (IMR) genes in bamboo and determined the TFs that significantly influence them. Among these, DOFs were found to have widespread effects and potentially significant impacts on their expression. We identified specific DOF members in Dendrocalamus latiflorus with binding abilities through homology with Arabidopsis DOF proteins, and established connections between some of these members and IMR genes using RNA-seq data. Additionally, molecular docking confirmed the binding interactions between these DlDOFs and the DOF binding sites in the promoter regions of IMR genes. The co-expression relationship between the two gene sets was further validated using q-PCR experiments. This study paves the way for research into iron metabolism pathways in bamboo and lays the foundation for understanding the role of DOF TFs in D. latiflorus.

Various exact solutions to the time-fractional nonlinear Schrödinger equation via the new modified Sardar sub-equation method

We aim to investigates the nonlinear Schrödinger equation including time-fractional derivative in (3+1)-dimensions by considering cubic and quantic terms The modified Sardar sub-equation method is used that lead to the discovery of a unique class of optical solutions. To transform the suggested nonlinear equation into an ordinary differential equation, we applied wave transformations, resulting in a set of nonlinear equations that offer diverse solution scenarios. The derived solutions encompass dark, wave, bright, mixed dark-bright, bell-shape, kink-shape, and singular soliton solutions. To enhance our understanding of the dynamic behavior exhibited by these solitons under varying time parameter values, visual simulations through a variety of graphs is presented. Furthermore, a comprehensive comparison is conducted, exploring a range of values for the conformable fractional order parameter. This comparison aims to highlight on the influence of fractional order variations on the solutions, contributing valuable insights into the nuanced dynamics of the system. Overall, this study serves to advance our understanding of nonlinear processes, and its potential applications in real-life phenomena. In the field of nonlinear optics, this equation can describe the propagation of optical pulses in nonlinear media. It helps in understanding the behavior of intense laser beams as they propagate through materials exhibiting nonlinear optical effects such as self-focusing, self-phase modulation, and optical solitons.

Self-Assembly of Polymers and Their Applications in the Fields of Biomedicine and Materials.

Polymer self-assembly can prepare various shapes and sizes of pores, making it widely used. The complexity and diversity of biomolecules make them a unique class of building blocks for precise assembly. They are particularly suitable for the new generation of biomaterials integrated with life systems as they possess inherent characteristics such as accurate identification, self-organization, and adaptability. Therefore, many excellent methods developed have led to various practical results. At the same time, the development of advanced science and technology has also expanded the application scope of self-assembly of synthetic polymers. By utilizing this technology, materials with unique shapes and properties can be prepared and applied in the field of tissue engineering. Nanomaterials with transparent and conductive properties can be prepared and applied in fields such as electronic displays and smart glass. Multi-dimensional, controllable, and multi-level self-assembly between nanostructures has been achieved through quantitative control of polymer dosage and combination, chemical modification, and composite methods. Here, we list the classic applications of natural- and artificially synthesized polymer self-assembly in the fields of biomedicine and materials, introduce the cutting-edge technologies involved in these applications, and discuss in-depth the advantages, disadvantages, and future development directions of each type of polymer self-assembly.

The Prevalence of Acute Compartment Syndrome in Pediatric Tibial Tubercle Fractures.

Tibial tubercle fractures are a unique class of pediatric orthopaedic injuries that frequently necessitate surgical treatment and strict monitoring due to the associated risk of acute compartment syndrome (ACS). However, current literature is conspicuously limited in its ability to estimate the risk of ACS after these fractures. Therefore, the purpose of this study is to utilize a nationwide database to estimate the prevalence of ACS after pediatric tibial tubercle fractures. We utilized the Healthcare Cost and Utilization Project's Kids' Inpatient Database (2019) to identify all pediatric patients, 18 years of age and under, with isolated tibial tubercle fractures (International Classification of Diseases, 10th revision Clinical Modification S82.151-S82.156) and ACS (T79.A0, T79.A2, T79.A29). Patients were excluded if they had additional lower extremity injuries (ie, tibial shaft, plateau, etc). A subanalysis was conducted for those undergoing fasciotomy, with and without an ACS diagnosis. Among the 591 isolated tibial tubercle fractures, there were 8 ACS cases for a prevalence of 1.35%. There were 22 (3.72%) additional cases of fasciotomy without an ACS diagnosis. All ACS cases were diagnosed during the original hospitalization; all were male and had closed fractures. The cohort included 469 teenagers (13+ years) and 77 pre-teens, with 40 females and 506 males. Racial demographics: 132 white, 232 black, 112 Hispanic, 15 Asian, 4 Native American, 23 unknown, and 28 others. No significant associations were found between ACS and age, race, insurance status, mechanism of injury, or hospital region. The rate of ACS in pediatric tibial tubercle fractures appears to be much lower than previously reported, at 1.35%. However, the nearly three-fold higher prevalence of fasciotomy without an ACS diagnosis, suggests a generous use of prophylactic fasciotomies and/or an undercharacterization of actual ACS cases from miscoding. This is the first and largest study to employ a nationally representative database to investigate the prevalence of ACS after tibial tubercle fractures. Level III.

Cascade C-H Activation and Two C-C Bond Forming in Reaction of Azalutetacyclopentadiene with 2-Methylbenzonitriles.

Azametallacyclopentadienes are an important class of metallacycles as the key intermediates in metal-promoted or catalyzed carbon-carbon coupling reaction of nitriles and alkynes. Rare-earth azametallacyclopentadienes have shown various reactivity toward nitriles, depending on the substituents of nitriles. The reaction of azalutetacyclopentadienes toward 2-methylbenzonitriles has been investigated in this work, which selectively affords the fused 7-5-6-membered azalutetacycles as products. Computational studies reveal that the reaction of azalutetacyclopentadienes toward 2-methylbenzonitriles selectively initiates with the remote activation of the benzylic C-H bond by the Lu-N bond, followed by the intramolecular nucleophilic attack from the deprotonated benzylic carbon to form a C-C bond. Subsequently, the high ring strain promoted the generation of the uncoordinated carbanion dissociated from the lutetium center, which then undergoes intramolecular nucleophilic attack toward C=N triple bond to give the final product containing fused 7-5-6-membered azalutetacycle. This work not only achieves highly selective three-step cascade reaction to form a unique class of rare-earth metallacycle, but also provides a new idea for the transformation of unsaturated substrates with C-H bonds that can be activated.

Indolizidines from Actinomycetes: An Overview of Producers, Biosynthesis and Bioactivities.

Indolizidines have long been recognized for their valuable bioactivities, their common feature being a bicyclic structure connected via a nitrogen atom. Traditionally, plants have been identified as the primary producers. However, recent discoveries have revealed that certain bacterial strains belonging to the genus of actinomycetes also possess the ability to synthesize various indolizidine-based compounds. Among these strains, Streptomyces sp. HNA39, Saccharopolyspora sp. RL78, and Streptomyces NCIB 11649 have been identified as producers of cyclizidines, characterized by their distinctive cyclopropyl moiety. Additionally, Streptomyces griseus OS-3601 synthesizes a unique class of indolizidine derivatives known as iminimycins, distinguished by their rare imine-cation structure. Protoplast fusion of a Streptomyces griseus strain with Streptomyces tenjimariensis resulted in a new indolizidine named indolizomycin. This review aims to provide an overview of known bacterial indolizidine producers, summarize current knowledge regarding the biosynthesis of cyclizidines and iminimycins, and assess their respective bioactivities.

Assessment of wafer scale MoS2 atomic layers grown by metal-organic chemical vapor deposition using organo-metal, organo-sulfide, and H2S precursors.

Transition Metal Dichalcogenides (TMDs) are a unique class of materials that exhibit attractive electrical and optical properties which have generated significant interest for applications in microelectronics, optoelectronics, energy storage, and sensing. Considering the potential of these materials to impact such applications, it is crucial to develop a reliable and scalable synthesis process that is compatible with modern industrial manufacturing methods. Metal-organic chemical vapor deposition (MOCVD) offers an ideal solution to produce TMDs, due to its compatibility with large-scale production, precise layer control, and high material purity. Optimization of MOCVD protocols is necessary for effective TMD synthesis and integration into mainstream technologies. Additionally, improvements in metrology are necessary to measure the quality of the fabricated samples more accurately. In this work, we study MOCVD of wafer-scale molybdenum disulfide (MoS2) utilizing two common chalcogen precursors, H2S and DTBS. We then develop a metrology platform for wafer scale samples quality assessment. For this, the coalesced films were characterized using Raman spectroscopy, atomic force microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, and Kelvin probe force microscopy. We then correlate the structural analysis of these grown films with electrical performance by using aerosol jet printing to fabricate van der Pauw test structures and assess sheet resistance.

Spectropolarimetric view of the gamma-ray emitting NLS1 1H0323 + 342

ABSTRACT The gamma-ray emitting narrow-line Seyfert 1 galaxies are a unique class of objects that launch powerful jets from relatively lower-mass black hole systems compared to the Blazars. However, the black hole masses estimated from the total flux spectrum suffer from the projection effect, making the mass measurement highly uncertain. The polarized spectrum provides a unique view of the central engine through scattered light. We performed spectropolarimetric observations of the gamma-ray emitting narrow-line Seyfert 1 galaxy 1H0323 + 342 using SPOL/MMT. The degree of polarization and polarization angle are 0.122 $\pm$ 0.040 per cent and 142 $\pm$ 9 degrees, while the H $\alpha$ line is polarized at 0.265 $\pm$ 0.280 per cent. We decomposed the total flux spectrum and estimated broad H $\alpha$ full width at half maximum of 1015 km s$^{-1}$. The polarized flux spectrum shows a broadening similar to the total flux spectrum, with a broadening ratio of 1.22. The Monte Carlo radiative transfer code ‘STOKES’ applied to the data provides the best fit for a small viewing angle of 9–24 deg and a small optical depth ratio between the polar and the equatorial scatters. A thick broad-line region with significant scale height can explain a similar broadening of the polarized spectrum compared to the total flux spectrum with a small viewing angle.

The quasiprimitive almost elusive groups

Let [Formula: see text] be a nontrivial transitive permutation group on a finite set [Formula: see text] and recall that an element of [Formula: see text] is a derangement if it has no fixed points. Derangements always exist by a classical theorem of Jordan, but there are so-called elusive groups that do not contain any derangements of prime order. In a recent paper, Burness and the author introduced the family of almost elusive groups, which contain a unique conjugacy class of derangements of prime order. In this paper, we complete the classification of the quasiprimitive almost elusive groups.

On the effect of strain rate during the cyclic compressive loading of liquid crystal elastomers and their 3D printed lattices

Nematic liquid crystal elastomers (LCEs) are a unique class of network polymers with the potential for enhanced mechanical energy absorption and dissipation capacity over conventional network polymers because they exhibit both conventional viscoelastic behavior and soft-elastic behavior (nematic director changes under shear loading). This additional inelastic mechanism makes them appealing as candidate damping materials in a variety of applications from vibration to impact. The lattice structures made from the LCEs provide further mechanical energy absorption and dissipation capacity associated with packing out the porosity under compressive loading.Understanding the extent of mechanical energy absorption, which is the work per unit mass (or volume) absorbed during loading, versus dissipation, which is the work per unit mass (or volume) dissipated during a loading cycle, requires measurement of both loading and unloading response. In this study, a bench-top linear actuator was employed to characterize the loading-unloading compressive response of polydomain and monodomain LCE polymers and polydomain LCE lattice structures with two different porosities (nominally, 62% and 85%) at both low and intermediate strain rates at room temperature. As a reference material, a bisphenol-A (BPA) polymer with a similar glass transition temperature (9 °C) as the nematic LCE (4 °C) was also characterized at the same conditions for comparing to the LCE polymers. Based on the loading-unloading stress-strain curves, the energy absorption and dissipation for each material at different strain rates (0.001, 0.1, 1, 10 and 90 s-1) were calculated with considerations of maximum stress and material mass/density. The strain-rate effect on the mechanical response and energy absorption and dissipation behaviors was determined. The energy dissipation ratio was also calculated from the resultant loading and unloading stress-strain curves. All five materials showed significant but different strain rate effects on energy dissipation ratio. The solid LCE and BPA materials showed greater energy dissipation capabilities at both low (0.001 s−1) and high (above 1 s−1) strain rates, but not at the strain rates in between. The polydomain LCE lattice structure showed superior energy dissipation performance compared with the solid polymers especially at high strain rates.

Engineering Visible to Near-Infrared Luminescence through a Selective Doping Strategy for High-Performance Temperature Sensing.

Luminescence nanothermometers have garnered considerable attention due to their noncontact measurement, high spatial resolution, and rapid response. However, many nanothermometers employing single-mode measurement encounter challenges regarding their relative sensitivity. Herein, a unique class of tunable upconversion (UC) and downshifting (DS) luminescence covering the visible to near-infrared range (400-1700 nm) is reported, characterized by the superior Tm3+, Ho3+, and Er3+ emissions induced by efficient energy transfer. The outstanding negative thermal expansion characteristic of ScF3 nanocrystals has been found to guide excitation energy toward the relevant emitting states in the Yb3+-Ho3+-Tm3+-codoped system, consequently resulting in remarkable near-infrared III (NIR-III) luminescence at ∼1625 nm (Tm3+:3F4 → 3H6 transition), which in turn presents numerous opportunities for designing multimode ratiometric luminescence thermometry. Furthermore, by facilitating phonon-assisted energy transfer in Er3+-Ho3+-codoped systems, the luminescence intensity ratio (LIR) of 4I13/2 of Er3+ and 5I6 of Ho3+ in ScF3:Yb3+/Ho3+/Er3+ exhibits a strong temperature dependence, enabling NIR-II/III luminescence thermometry with superior thermal sensitivity and resolution (Sr = 0.78% K-1, δT = 0.64 K). These findings not only underscore the distinctive and ubiquitous attributes of lanthanide ion-doped nanomaterials but also hold significant implications for crafting luminescence thermometers with unparalleled sensitivity.

Exploring the Recent Pioneering Developments of Small Molecules in Antimalarial Drug Armamentarium: A Chemistry Prospective Appraisal.

Malaria is a very destructive and lethal parasitic disease that causes significant mortality worldwide, resulting in the loss of millions of lives annually. It is an infectious disease transmitted by mosquitoes, which is caused by different species of the parasite protozoan belonging to the genus Plasmodium. The uncontrolled intake of antimalarial drugs often employed in clinical settings has resulted in the emergence of numerous strains of plasmodium that are resistant to these drugs, including multidrug-resistant strains. This resistance significantly diminishes the effectiveness of many primary drugs used in the treatment of malaria. Hence, there is an urgent need for developing unique classes of antimalarial drugs that function with distinct mechanisms of action. In this context, the design and development of hybrid compounds that combine pharmacophoric properties from different lead molecules into a single unit gives a unique perspective towards further development of malaria drugs in the next generation. In recent years, the field of medicinal chemistry has made significant efforts resulting in the discovery and synthesis of numerous small novel compounds that exhibit potent antimalarial properties, while also demonstrating reduced toxicity and desirable efficacy. In light of this, we have reviewed the progress of hybrid antimalarial agents from 2021 up to the present. This manuscript presents a comprehensive overview of the latest advancements in the medicinal chemistry pertaining to small molecules, with a specific focus on their potential as antimalarial agents. As possible antimalarial drugs that might target both the dual stage and multi-stage stages of the parasite life cycle, these small hybrid molecules have been studied. This review explores a variety of physiologically active compounds that have been described in the literature in order to lay a strong foundation for the logical design and eventual identification of antimalarial drugs based on lead frameworks.

Next-Generation Vaccine Development with Nanomaterials: Recent Advances, Possibilities, and Challenges.

Nanomaterials are becoming important tools for vaccine development owing to their tunable and adaptable nature. Unique properties of nanomaterials afford opportunities to modulate trafficking through various tissues, complement or augment adjuvant activities, and specify antigen valency and display. This versatility has enabled recent work designing nanomaterial vaccines for a broad range of diseases, including cancer, inflammatory diseases, and various infectious diseases. Recent successes of nanoparticle vaccines during the coronavirus disease 2019 (COVID-19) pandemic have fueled enthusiasm further. In this review, the most recent developments in nanovaccines for infectious disease, cancer, inflammatory diseases, allergic diseases, and nanoadjuvants are summarized. Additionally, challenges and opportunities for clinical translation of this unique class of materials are discussed.