bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Comparative Analysis of Carboxylic Acid Composition of Four Iris Species from Ukraine
Authors: Mykhailenko Olha , Gudžinskas Zigmantas , Romanova Svitlana , Orlova Tetyana , Kozyra Sofiia , Harna Svitlana , Volochai Victoriia 
Published: January 2021

AbstractThe present article reports results of analysis of carboxylic acids in leaves of Iris species from Ukraine using a gas chromatography (GC) method with mass spectrometric (MS) detection (GC/MS). Carboxylic acids play significant roles in contemporary society as evidenced by multiple applications in fields of medicine, agriculture, pharmacy, food, and other industries. Study of natural plant products as a source of organic acids is of particular interest. Carboxylic acid composition of leaves of Iris hungarica Waldst. & Kit., Iris germanica L., Iris pallida Lam., and Iris variegate L. was studied for the first time applying GC/MS method. The mass spectrums of compounds were matched with NIST and WILEY Libraries. The GC/MS analysis revealed the presence of 26 common acids in the plant raw materials studied. The short‐chain carboxylic acids, such as citric (1337.5–12364.4 mg/kg), malic (50.8–4558.0 mg/kg) and oxalic (1199.0–3435.2 mg/kg) acids were contained in significantly high quantity in all samples. Ferulic, p‐coumaric and vanillic acids were the most abundant among phenolic acids. α‐Linolenic acid was dominant in the leaves of I. germanica (869.5 mg/kg), I. pallida (753.3 mg/kg), and I. variegate (250.3 mg/kg) among polyunsaturated fatty acids, however, linoleic acid prevailed in the plant raw material of I. hungarica (1150.7 mg/kg). Since the leaves of Iris species studied contain carboxylic acids with diverse pharmacological activity, extracts of these raw materials are perspective for development food supplements and medicines.
IsPETase Is a Novel Biocatalyst for Poly(ethylene terephthalate) (PET) Hydrolysis
Authors: Kan Yeyi , He Lihui , Luo Yunzi , Bao Rui 
Published: January 2021

AbstractPoly(ethylene terephthalate) (PET) is one of the most widely used synthetic polyesters, but also a major cause of plastic pollution. Because the chemical degradation of PET would be uneconomical and rather burdensome, considerable efforts have been devoted to exploring enzymatic processes for the disposal of PET waste. Many PET‐hydrolyzing enzymes have been reported in recent decades, some of which demonstrate excellent potential for industrial applications. This review sets out to summarize the state of investigation into IsPETase, a cutinase‐like enzyme from Ideonella sakaiensis possessing ability to degrade crystalline PET, and to gain further insight into the structure–function relationship of IsPETase. Benefiting from the continuing identification of novel cutinase‐like proteins and growing availability of the engineered IsPETase, we may anticipate future developments in this type of enzyme would generate suitable biocatalyst for industrial use.
Cleavage of an RNA Model Compound by an Arylmercury Complex
Authors: Saleh Lange Yakubu , Ora Mikko , Lönnberg Tuomas 
Published: January 2021

AbstractA water‐soluble arylmercury complex has been synthesized, and its ability to catalyze the cleavage of the phosphodiester linkage of the RNA model compound adenylyl‐3′,5′‐(2′,3′‐O‐methyleneadenosine) has been assessed over a pH range of 3–8.5 and a catalyst concentration range of 0–7 mM. In the presence of 1 mM catalyst, the observed pH–rate profile featured a new pH‐independent region between pH 6 and 7, the catalyzed reaction being as much as eight times faster than the background reaction. At pH 7, the acceleration increased linearly from three‐ to 17‐fold upon increasing the catalyst concentration from 1 to 7 mM. The linear dependence indicates a relatively low affinity of the catalyst for the substrate and, hence, the potential for considerable improvement on tethering to an appropriate targeting group, such as an oligonucleotide.
High‐Performance Reversed‐Phase Flash Chromatography Purification of Peptides and Chemically Modified Insulins
Authors: Sørensen Kasper K. , Mishra Narendra K. , Paprocki Maciej P. , Mehrotra Amit , Jensen Knud J. 
Published: January 2021

AbstractPreparative reversed‐phase HPLC is the established method for the purification of peptides, but has significant limitations. We systematically investigated the use of high‐performance reversed‐phase flash chromatography (HPFC) to rapidly purify laboratory‐scale quantities of crude, synthetic peptides and chemically modified insulins. We demonstrated these methods for a diverse set of peptides, including short, medium, and long peptides. Depending on the purity profile of the peptide, HPFC can be used either as the sole purification method, or as a pre‐purification method prior to final HPLC purification. Furthermore, HPFC is suitable for the purification of peptides that are not fully in solution. We provide guidelines for the HPFC of synthetic peptides and small proteins, including the choice of columns, eluents, and gradients. We believe that HPFC is a valuable alternative to HPLC purification of peptides and small proteins.
COVID‐19: Prolonged viral shedding in an HIV patient with literature review of risk factors for prolonged viral shedding and its implications for isolation strategies
Authors: Yousaf Muhammad , Hameed Mansoor , Alsoub Hussam , Khatib Mohamad , Jamal Wasim , Ahmad Mushtaq 
Published: January 2021

AbstractOur work highlights patients at risk of prolonged viral shedding in COVID‐19 and its implications for isolation strategies and explores possible solution by PCR‐CT value testing (cycle threshold value). We also review the impact of HIV on COVID‐19.
A multilobulated asymptomatic umbilical nodule revealing endometriosis
Authors: Chamli Amal , Souissi Asmahene , Alaoui Fatima , Chelly Ines , Eleuch Dalenda , Mokni Mourad 
Published: January 2021

AbstractPrimary umbilical endometriosis is unusual clinical presentation of endometriosis. Its diagnosis can be challenging due to lack of knowledge. This condition should be listed in the differential diagnosis of umbilical disorders.
Cooperative NHC‐based Catalytic System Immobilised onto Carbon Materials for the Cycloaddition of CO2 to Epoxides
Authors: Souleymanou Myriam Y. , El‐Ouahabi Fatima , Masdeu‐Bultó Anna M. , Godard Cyril 
Published: January 2021

AbstractNew pyrene‐tagged imidazolium salts and their corresponding carboxylates were synthesised and the latter tested as organocatalysts in the cycloaddition of CO2 with epoxides. The best performing organocatalyst was then non‐covalently immobilised onto carbon materials (carbon nanotubes (CNTs), reduced graphene oxide (rGO) and carbon beads (CBs)) via π‐π stacking interactions and their activity and recoverability in the cycloaddition reaction were studied. The heterogenised catalyst onto reduced graphene oxide (4 a@rGO) was recycled several times although a loss of activity was observed. This catalyst was also used for the transformation of a series of epoxides under mild conditions.
Promotion of Electrochemical Water Oxidation Activity of Au Supported Cobalt Oxide upon Addition of Cr: Insights using in situ Raman Spectroscopy
Authors: Das Abhinaba , Mohapatra Bapuji , Kamboj Vipin , Ranjan Chinmoy 
Published: January 2021

AbstractMixed metal oxides based on cobalt oxide are important target material as water oxidation catalyst in alkaline media. Significant enhancement of electrochemical oxygen evolution activity was observed for Au supported cobalt oxide, upon addition of Cr. CoOx/Au and Co[Cr]Ox/Au were studied side by side to understand the effects of the addition of Cr in such a system. The presence of Cr resulted in a significant lowering of onset potentials ∼150 mV. In‐situ Raman spectroscopy was used to characterize the material. The catalyst was found to develop into oxide entirely in situ. Cr was found to stabilize lower oxidation states of Co, both during catalyst formation and oxygen evolution. Isotopic substitution studies alongside in situ Raman Spectroscopy showed that OER onset potential strongly correlated with the appearance of metastable Au−OOH peak.
Electro‐Oxidation of Titanium Carbide Nanoparticles in Aqueous Acid Creates TiC@TiO2 Core‐Shell Structures
Authors: Nayak Pranati , Xie Ruo‐Chen , Palgrave Robert G. , Compton Richard G. 
Published: January 2021

AbstractTitanium carbide (TiC) is an attractive support material used in electro‐catalysis and sensing. We report the electrochemistry of TiC nanoparticles (NPs, 35–50 nm in diameter) in different electrolytes in the pH range of 0 to 8. The TiC NPs undergo irreversible oxidation in acidic, basic, and neutral media, attributed to the partial conversion into titanium dioxide (TiO2) with the amount of oxidation highly dependent on the pH of the solution. In H2SO4 (pH 0), multiple voltammetric scans revealed the conversion to be partial but repeated scans allowed a conversion approaching 100 % to be obtained with 20 scans generating a ca 60 % level of oxidation. The process is inferred to lead to the formation of TiC@TiO2 core‐shell nanoparticles (∼12.5 nm core radius and ∼5 nm shell width for a 60 % conversion) and this value sharply decreases with an increase of pH. Independent measurements were conducted at a single NP level (via nano‐impact experiments) to confirm the oxidation of the NPs, showing consistent agreement with the bulk measurements.
A new concept based on ensemble strategy and derivative for the quantitative analysis of infrared data
Authors: Yan Hong , Tang Guo , Xiong Yanmei , Min Shungeng 
Published: January 2021

AbstractPreprocessing and variable selection are the most widely used strategies to develop accurate predictive models based on infrared spectroscopy. In our study, a new conception that the derivative combined with ensemble strategy based on competitive adaptive reweighted sampling (CARS), stability competitive adaptive reweighted sampling (SCARS), Monte Carlo uninformative variables elimination (MCUVE), and bootstrapping soft shrinkage (BOSS) is put forward. The proposed concept makes the best of the derivative spectra information and successfully combines the strengths of derivative spectra, CARS, SCARS, MCUVE, BOSS, and ensemble submodels. Compared with other methods in this study, this new method can establish good calibration models without increasing the complexity from the perspective of an end user. Also, overfitting issues can be prevented. Derivative1st‐ECARS and Derivative1st‐ESCARS have shown significant improvements in partial least regression calibration based on the experiments of three datasets. The proposed concept shows great potential of the chemometrics approaches applied to infrared data in multivariate calibration.
The synthesis of carbon microspheres film composed of nano‐onions and its application as flexible supercapacitors
Authors: Zhang Miao , Zhao Naiqin , Li Xifei 
Published: January 2021

AbstractFlexible electrodes with superior mechanical and electrochemical properties are essential for flexible supercapacitors. A convenient and scalable colloidal film‐assisted chemical vapor deposition (CF‐CVD) method is developed for the one‐step fabrication of the carbon microspheres films composed of carbon nano‐onions (CMS‐CNO films). The influence of growth conditions (such as growth temperature, time, and gas ratio) during CF‐CVD process on the carbon structures and the growth mechanism of the CMS‐CNO films have been investigated. By controlling the growth conditions, the controllable preparation of CMS‐CNO films is realized. Such binder‐free films can be used for the assembly of flexible supercapacitors, and unique architecture can achieve excellent performance. Benefitting from the composite of nano‐micro zero dimensional structures, the performance of the film in supercapacitors is remarkably improved. At the current density of 5 mA cm−2, the area‐specific capacity can be 903 mF cm−2. When the current density is increased to 500 mA cm−2, the area‐specific capacity can be increased to 729 mF cm−2. This simple and low‐cost preparation process and the superb electrochemical performance suggest great potential applications of CMS‐CNO films in flexible supercapacitors.
Mechanochemical Synthesis of Catalytic Materials
Authors: Amrute Amol P. , De Bellis Jacopo , Felderhoff Michael , Schüth Ferdi 
Published: January 2021

AbstractThe mechanochemical synthesis of nanomaterials for catalytic applications is a growing research field due to its simplicity, scalability, and eco‐friendliness. Besides, it provides materials with distinct features, such as nanocrystallinity, high defect concentration, and close interaction of the components in a system, which are, in most cases, unattainable by conventional routes. Consequently, this research field has recently become highly popular, particularly for the preparation of catalytic materials for various applications, ranging from chemical production over energy conversion catalysis to environmental protection. In this Review, recent studies on mechanochemistry for the synthesis of catalytic materials are discussed. Emphasis is placed on the straightforwardness of the mechanochemical route—in contrast to more conventional synthesis—in fabricating the materials, which otherwise often require harsh conditions. Distinct material properties achieved by mechanochemistry are related to their improved catalytic performance.
Selective Cross‐Coupling of Unsaturated Substrates on AlI
Authors: Dmitrienko Anton , Pilkington Melanie , Nikonov Georgii I. 
Published: January 2021

AbstractThe AlI compound NacNacAl (1, NacNac = [ArNC(Me)CHC(Me)NAr]−, Ar = 2,6‐iPr2C6H3) serves as a template for the chemoselective coupling between carbonyls (benzophenone, fenchone, isophorone, p‐tolyl benzoate, N,N‐dimethylbenzamide, (1‐phenylethylidene)aniline) and pyridine. With the CH‐acidic ketone (1R)‐(+) camphor, the reaction affords a hydrido alkoxide compound of Al, formed as the result of enolization, whereas an enolizable imine, (1‐phenylethylidene)aniline, and the bulky ketone isophorone, still chemoselectively couple with pyridine. In contrast, reaction with the ester p‐tolyl benzoate results in cleavage of the ester bond together with replacement of the alkoxy group by a hydrogen atom of the pyridine moiety. This study demonstrates that for carbonyl substrates featuring phenyl substituents, the reaction proceeds via intermediate formation of η2(C,X)‐coordinated (X = O, N) carbonyl adducts, whereas the reaction of 1 with (R)‐(−)‐fenchone in the absence of pyridine leads to CH activation in the pendant isopropyl group of the Ar substituent of the NacNac ligand.
Trends and Prospects of Bimetallic Exsolution
Authors: Tang Chenyang , Kousi Kalliopi , Neagu Dragos , Metcalfe Ian S. 
Published: January 2021

AbstractSupported bimetallic nanoparticles used for various chemical transformations appear to be more appealing than their monometallic counterparts, because of their unique properties mainly originating from the synergistic effects between the two different metals. Exsolution, a relatively new preparation method for supported nanoparticles, has earned increasing attention for bimetallic systems in the past decade, not only due to the high stability of the resulting nanoparticles but also for the potential to control key particle properties (size, composition, structure, morphology, etc.). In this review, we summarize the trends and advances on exsolution of bimetallic systems and provide prospects for future studies in this field.
Synthesis and Electronic Properties of Directly Linked Dihydrodiazatetracene Dimers
Authors: Tanaka Katsuki , Sakamaki Daisuke , Fujiwara Hideki 
Published: January 2021

Abstract5,12‐Dihydro‐5,12‐diazatetracene (DHDAT) dimers with different substitution patterns are synthesized: a symmetric one with a C−C bond between the monomer units (1) and two asymmetric ones with a C−N bond between the monomer units (2 and 3). The DHDAT units are planar in the C−C linked dimer 1 but perpendicularly oriented in the C−N linked dimers 2 and 3 (from X‐ray analysis). The electronic ground‐state interaction between the two units is large in 1 and small in 2 and 3. The emission behavior of 3 is different from that of other dimers and its monomer; it displays positive solvatochromism, characteristic for electron donor–acceptor molecules, despite its donor–donor type structure. Compound 3 exhibits a unique multi‐step thermochromic emission behavior. The emission behavior is attributed to the asymmetric distribution of the HOMO and LUMO of DHDAT.
Total Synthesis of Tiacumicin B: Study of the Challenging β‐Selective Glycosylations**
Authors: Tresse Cédric , François‐Heude Marc , Servajean Vincent , Ravinder Rubal , Lesieur Clémence , Geiben Lucie , Jeanne‐Julien Louis , Steinmetz Vincent , Retailleau Pascal , Roulland Emmanuel , Beau Jean‐Marie , Norsikian Stéphanie 
Published: January 2021

AbstractWe give a full account of the total synthesis of tiacumicin B (Tcn‐B), a natural glycosylated macrolide with remarkable antibiotic properties. Our strategy is based on our experience with the synthesis of the tiacumicin B aglycone and on unique 1,2‐cis‐glycosylation steps. We used sulfoxide anomeric leaving‐groups in combination with a remote 3‐O‐picoloyl group on the donors that allowed highly β‐selective rhamnosylation and noviosylation that rely on H‐bond‐mediated aglycone delivery. The rhamnosylated C1–C3 fragment was anchored to the C4–C19 aglycone fragment by a Suzuki–Miyaura cross‐coupling. Ring‐size‐selective Shiina macrolactonization provided a semiglycosylated aglycone that was engaged directly in the noviolysation step with a virtually total β‐selectivity. Finally, a novel deprotection method was devised for the removal of a 2‐naphthylmethyl ether on a phenol, and efficient removal of all the protecting groups provided synthetic tiacumicin B.
Bambusuril Macrocycles as Mediators of Supramolecular Interactions: Application to the Europium Cage Helicate
Authors: Hamacek Josef , Sokolov Jan , Šindelář Vladimír 
Published: January 2021

AbstractHerein, it is shown how bambusurils can be used for tuning and/or characterizing supramolecular systems. Indeed, the addition of bambusurils as anion scavengers to metal‐mediated self‐assemblies allows manipulation of the subtle equilibria in the given system. This is demonstrated for the case of the tetranuclear europium helical cage, which is well suited to different applications. Among the reported results, experimental evidence is provided showing that perchlorate and triflate anions act as a molecular template for the cage assembly. The complexation of inorganic anions with neutral bambusurils resulted in bulky non‐coordinating counterions that may trigger the self‐assembly process or stimulate specific interactions between components. Moreover, bambusuril was able to selectively remove coordinating nitrates from the mixture with non‐coordinating anions, enabling the regeneration of the helical cage.
5‐Aza‐7‐deazaguanine–Isoguanine and Guanine–Isoguanine Base Pairs in Watson–Crick DNA: The Impact of Purine Tracts, Clickable Dendritic Side Chains, and Pyrene Adducts
Authors: Zhang Aigui , Kondhare Dasharath , Leonard Peter , Seela Frank 
Published: January 2021

AbstractThe Watson–Crick coding system depends on the molecular recognition of complementary purine and pyrimidine bases. Now, the construction of hybrid DNAs with Watson–Crick and purine–purine base pairs decorated with dendritic side chains was performed. Oligonucleotides with single and multiple incorporations of 5‐aza‐7‐deaza‐2′‐deoxyguanosine, its tripropargylamine derivative, and 2′‐deoxyisoguanosine were synthesized. Duplex stability decreased if single modified purine–purine base pairs were inserted, but increased if pyrene residues were introduced by click chemistry. A growing number of consecutive 5‐aza‐7‐deazaguanine–isoguanine base pairs led to strong stepwise duplex stabilization, a phenomenon not observed for the guanine–isoguanine base pair. Spacious residues are well accommodated in the large groove of purine–purine DNA tracts. Changes to the global helical structure monitored by circular dichroism spectroscopy show the impact of functionalization to the global double‐helix structure. This study explores new areas of molecular recognition realized by purine base pairs that are complementary in hydrogen bonding, but not in size, relative to canonical pairs.
Chiral Triptycenes: Concepts, Progress and Prospects
Authors: Khan Md. Nasim , Wirth Thomas 
Published: January 2021

AbstractTriptycenes have been established as unique scaffolds because of their backbone π‐structure with a propeller‐like shape and saddle‐like cavities. They are some of the key organic molecules that have been extensively studied in polymer chemistry, in supramolecular chemistry and in material science. Triptycenes become chiral molecules when substituents are unsymmetrically attached in at least two of their different aromatic rings. This Minireview highlights the chirality of triptycenes from basics to an advanced stage for the development of functional molecules.
The Simplest Model for Doped Poly(3,4‐ethylenedioxythiophene) (PEDOT): Single‐crystalline EDOT Dimer Radical Cation Salts
Authors: Kameyama Ryohei , Fujino Tomoko , Dekura Shun , Kawamura Mitsuaki , Ozaki Taisuke , Mori Hatsumi 
Published: January 2021

AbstractAlthough doped poly(3,4‐ethylenedioxythiophene) (PEDOT) is extensively used in electronic devices, their molecular‐weight distributions and inadequately defined structures have hindered the elucidation of their underlying conduction mechanism. In this study, we introduce the simplest discrete oligomer models: EDOT dimer radical cation salts. Single‐crystal structural analyses revealed their one‐dimensional (1D) columnar structures, in which the donors were uniformly stacked. Band calculations identified 1D metallic band structures with a strong intracolumnar orbital interaction (band width W≈1 eV), implying the origin of the high conductivity of doped PEDOT. Interestingly, the salts exhibited semiconducting behavior reminiscent of genuine Mott states as a result of electron–electron repulsion (U) dominant over W. This study realized basic models with tunable W and U to understand the conduction mechanism of doped PEDOT through structural modification in oligomers, including the conjugation length.
Pd‐Catalyzed C(sp2)−H Alkoxycarbonylation of Phenethyl‐ and Benzylamines with Chloroformates as CO Surrogates
Authors: Andrade‐Sampedro Paula , Matxain Jon M. , Correa Arkaitz 
Published: January 2021

AbstractThe site‐selective functionalization of C−H bonds within a complex molecule remains a challenging task of capital synthetic importance. Herein, an unprecedented Pd‐catalyzed C(sp2)−H alkoxycarbonylation of phenylalanine derivatives and other amines featuring picolinamide as the directing group (DG) is reported. This oxidative coupling is distinguished by its scalability, operational simplicity, and avoids the use of toxic carbon monoxide as the C1 source. Remarkably, the easy cleavage of the DG enables the efficient assembly of isoindolinone compounds. Density Functional Theory calculations support a PdII/PdIV catalytic cycle.
Extended Peptide Nucleic Acid Nucleobases Based on Isoorotic Acid for the Recognition of A–U Base Pairs in Double‐Stranded RNA
Authors: Brodyagin Nikita , Maryniak Aubrey L. , Kumpina Ilze , Talbott John M. , Katkevics Martins , Rozners Eriks , MacKay James A. 
Published: January 2021

AbstractPeptide nucleic acids (PNA) with extended isoorotamide containing nucleobases (Io) were designed for binding A–U base pairs in double‐stranded RNA. Isothermal titration calorimetry and UV thermal melting experiments revealed improved affinity for A–U using the Io scaffold in PNA. PNAs having four sequential Io extended nucleobases maintained high binding affinity.