bluuebunny/crossref_metadata_2025 huggingface dataset:
Regulation of the 28 kDa heat shock protein by retinoic acid during differentiation of human leukemic HL‐60 cells
Authors: Specter Neil Lee , Mehlen Patrick , Ryan Colleen , Hardy L. , Samson William , Levine Herbert , Nadler Lee Marshall , Fabre Nathalie , Arrigo André-Patrick
Published: July 2002

Dysregulation of hematopoietic cellular differentiation contributes to leukemogenesis. Unfortunately, relatively little is known about how cell differentiation is regulated. Considering that heat shock proteins (hsp) and specifically the small hsps have been increasingly linked to growth regulation, we sought to determine whether the mammalian small hsp (hsp28) is a growth‐regulatory candidate during hematopoietic cell differentiation. Because of its effects on cell growth and differentiation and its increasing clinical use as a differentiating agent, we examined the effect of retinoic acid (RA) on hsp28 during differentiation of the human leukemic HL‐60 cell line. Although hsp28 was constitutively expressed at low levels in untreated HL‐60 cells, steady state hsp28 protein increased transiently, concomitant with the onset of G1 cell cycle arrest. Furthermore, hsp28 phosphorylation transiently increased within one hour following treatment with RA. Interestingly, in contrast to other differentiating agents the induction of hsp28 by RA was post‐transcriptionally mediated with hsp28 protein and mRNA being discordantly regulated. These observations underscore the complex regulation of hsp28 by RA during granulocytic differentiation of human leukemic cells and indicate hsp28 as an intermediary in the pathway through which retinoids exert their growth and differentiative effects.
Complete amino acid sequence of porcine adrenomedullin and cloning of cDNA encoding its precursor
Authors: Kitamura Kazuo , Kangawa Kenji , Kojima Masayasu , Ichiki Yoshinari , Matsuo Hisayuki , Eto Tanenao
Published: July 2002

Porcine adrenomedullin was isolated from adrenal medulla extract and its amino acid sequence was determined. The peptide is identical to human adrenomedullin with a single replacement of Gly for Asn at position 40. The cDNA clone encoding the porcine adrenomedullin precursor was isolated and sequenced. The precursor for adrenomedullin (preproadrenomedullin) is 188 amino adds in length, including the adrenomedullin sequence, followed by a glycine (the amide donor). In addition to adrenomedullin, proadrenomedullin (proAM) contains a candidate for a unique 20‐residue peptide, proAM‐N20, whose carboxy‐terminus may be amidated. By RNA blot analysis, porcine adrenomedullin mRNA was found to be highly expressed in several porcine tissues including lung and kidney as well as adrenal medulla.
The major cold shock protein of Bacillus subtilis CspB binds with high affinity to the ATTGG‐ and CCAAT sequences in single stranded oligonucleotides
Authors: Graumann Peter , Marahiel Mohamed A.
Published: July 2002

We have characterized the nucleic acid binding properties of the major cold shock protein of Bacillus subtilis, CspB. CspB is a member of the cold shock domain (CSD) family, which is widespread among pro‐ and eukaryotes and shares the nucleic acid binding domain CSD. The CSD domain is highly conserved and binds with strong affinity to the Y‐box motif, a cis‐element that contains the CTG

AA sequence. In a series of gel retardation experiments using oligonucleotides, which contain the Y‐box motif and altered sequences, we show the preferential binding of CspB to single‐stranded DNA that contains the ATTGG as well as the complementary CCAAT Y‐box core sequence. In contrast CspB exhibits lower affinity to altered Y‐box core sequences. Dependent on the length of the oligonucleotide and the degree of sequence deviation from the Y‐box core sequence 3‐ to over 10‐fold overexcess of CspB was needed for complete retardation.
The α‐subunits of G‐proteins G12 and G13 are palmitoylated, but not amidically myristoylated
Authors: Veit Michael , Nürnberg Bernd , Spicher Karsten , Harteneck Christian , Ponimaskin Ewgeni , Schultz Günter , Schmidt Michael F.G.
Published: July 2002

The α‐subunits of the G‐proteins G12 and G13, were expressed with a baculovirus system in insect cells and analysed for acylation. Both proteins incorporated tritiated palmitic and to a lesser extent also tritiated myristic acid. Radiolabel from both fatty acids was sensitive to treatment with neutral hydroxylamine. This result supports a thioester‐type fatty acid bond and argues against amidical N‐myristoylation. Fatty acid analysis after labeling with [3H]palmitic acid showed that palmitate represents the predominant fatty acid linked to Gα12 and Gα13. Separation of cells into cytosolic and membranous fractions revealed that palmitoylated α‐subunits of G12 were exclusively membrane‐bound, whereas [35S]methionine‐labeled proteins were detected in soluble and particulate fractions. Inhibition of protein synthesis with cycloheximide did not block palmitoylation of the α‐subunits. which indicates that palmitoylation occurs independently of protein synthesis.
Chromosomal localization of the protein tyrosine phosphatase G1 gene and characterization of the aberrant transcripts in human colon cancer cells
Authors: Takekawa Mutsuhiro , Itoh Fumio , Hinoda Yuji , Adachi Masaaki , Ariyama Takeshi , Inazawa Johji , Imai Kohzoh , Yacht Akira
Published: July 2002

We have recently described the isolation of the human PTPG1 gene which encodes a member of intracellular protein tyrosine phosphatases that may be candidates for tumor suppressor genes. In order to investigate the abnormality of the PTPG1 transcript in various human cancer cell lines, we have analyzed the consensus catalytic region of PTPG1 cDNA, using the reverse transcriptionpolymerase chain reaction. In a colorectal carcinoma cell line, DLD‐1, we found three aberrant transcripts. Sequencing analysis revealed that one had a missense point mutation and the remainders contained 77 bp and 173 bp deletions, respectively. These alterations might directly affect their phosphatase activities. Our findings provide the first evidence for the aberrant transcripts of the protein tyrosine phosphatase in human cancer cells, and suggest that the aberration of PTPG1 gene might be involved in the tumororigenesis. Moreover, the human PTPG1 gene is localized on chromosome 7q11.23, a region with frequent abnormalities implicated in some human cancers.
Protein kinase C activates capacitative calcium entry in the insulin secreting cell line RINm5F
Authors: Bode Hans-Peter , Göke Burkhard
Published: July 2002

This study examines the calcium store‐regulated (capacitative) calcium influx pathway in the endocrine pancreatic cell line RINm5F, utilizing thapsigargin. After preincubation of the cells with the phorbol ester TPA, thapsigargin induced a sustained elevation of cytosolic calcium as well as a sustained stimulation of manganese entry, the latter being used to assess calcium influx. Thapsigargin given alone provoked a smaller and only transient elevation of cytosolic calcium and stimulation of manganese entry. The protein kinase C inhibitor staurosporine antagonized the effect of the phorbol ester. Verapamil, nifedipine, or measures to hyperpolarize the cells exerted no inhibitory action against this effect, which excludes an involvement of voltage‐dependent calcium channels. In conclusion, our data shows for the first time that protein kinase C stimulation activates the capacitative calcium influx pathway of endocrine pancreatic insulin‐producing cells.
Effect of sialic acid removal on the antibody response to the third variable domain of human immunodeficiency virus type‐1 envelope glycoprotein
Authors: Benjouad Abdelaziz , Mabrouk Kamel , Gluckman Jean Claude , Fenouillet Emmanuel
Published: July 2002

The gp160 envelope glycoprotein of human immunodeficiency virus type‐1 (HIV‐1) is an essential component of current vaccine trials. The giycans of gp160, part of which are highly sialylated, have been shown to influence gp160 immunogenicity. Here, using a panel of synthetic V3 peptides, we characterized the anti‐V3 antibodies generated in rabbits immunized by desialylated recombinant gp160LAI. Amino acid residues flanking the GPGR tip of V3 were necessary for the recognition by anti‐V3 antibodies raised against either the native or desialylated gp160. Both types of antibodies reacted to V3 peptides of MN and SF2 strains and with a North American/European V3 consensus peptide, while anti‐desialylated gp 160LAI antibodies reacted in addition to the V3 of CDC4, WMJ2 and NY5 strains. Yet, the V3 peptides did not significantly differ in their secondary structure, as determined by circular dichroism. The titer and avidity for V3MN of anti‐desialylated gp160LAI, antibodies were significantly lower than those of anti‐native gp160LAI, which likely accounts for the inability of anti‐desialylated gp160LAI sera to neutralize HIV‐1MN‐mduced syncytia. These results indicate that V3 immunogenicity may be influenced by subtle directed changes in the gp160 glycosylation pattern.
Phospholipase D activation in fibroblast membranes by the α and β isoforms of protein kinase C
Authors: Conricode Kevin M. , Smith Jennie L. , Burns David J. , Exton John H.
Published: July 2002

The regulation of phosphatidylcholine‐hydrolyzing phospholipase D (PLD) by protein kinase C (PRC) in membranes of Chinese hamster lung fibroblasts (CCL39) was studied using conventional PKC isoforms α, β and γ isolated from rat brain and recombinant PKC isoforms. Cells were incubated with [14C]choline to label endogenous phosphatidylcholine before membranes were prepared and assayed for release of 14C]choline. PKCα was the most potent activator of PLD, producing a maximal effect at approximately 0.1 . PKCβ also stimulated PLD but was less potent and less efficacious, whereas PKCγ was ineffective. Stimulation required addition of a PKC activator, but the isoform specificity was the same whether phorbol 12‐myristate 13‐acetate (PMA) or Ca2+ was used. Recombinant Ca2+‐independent PKC isoforms δ, ϵ, and ζ, failed to stimulate PLD, but recombinant PKCβ1 stimulated PLD in a manner similar to the purified brain PKCβ. Immunoblot analysis of the soluble fraction of CCL 39 fibroblasts detected only the α and ζ isoforms of PKC. The results suggest that PKCα and β are activators of PLD and that PKCα is responsible for the activation in these fibroblasts.
Highly polarized expression of carbohydrate‐binding protein p33/41 (annexin IV) on the apical plasma membrane of epithelial cells in renal proximal tubules
Authors: Kojima Kyoko , Utsumi Hideko , Ogawa Haruko , Matsumoto Isamu
Published: July 2002

p33/41 is a Ca2+‐dependent carbohydrate‐binding protein and is identical to annexin IV, a member of the annexin protein family. The localization of p33/41 in bovine kidney specimens was investigated immununohistochemically by use of specific polyclonal antibodies. The most interesting finding on immunostaining was that p33/41 was highly concentrated in the apical plasma membrane of the epithelial cells in the proximal tubules contrary to the distribution throughout the cytoplasm in the papillary ducts and papilla epithelium. The enrichment of p33/41 m the apical membrane was confirmed by immunoblotting of the brush border membrane fraction prepared from a kidney homogenate. Sequential extraction with EDTA and Triton X‐100, and a partition experiment with Triton X‐114 revealed that most p33/41 associates with the renal brush border membrane in a Ca2+‐independent manner and is integrated into the membrane like intrinsic membrane proteins.
Annexin‐I inhibits phospholipase A2 by specific interaction, not by substrate depletion
Authors: Kim Kyoung Mi , Kirn Dai Kyung , Park Young Min , Kim Chong-Kook , Na Doe Sun
Published: July 2002

Annexin‐I is a calcium dependent phospholipid binding and phospholipase A2 (PLA2) inhibitory protein. A ‘substrate depletion’ model has been proposed for the mechanism of PLA2 inhibition by annexin‐I in studies with 14 to 18 kDa PLA2s. Herein, we have studied the inhibition mechanism using 100 kDa cytosolic PLA2 from porcine spleen. The inhibition has been measured at various substrate and calcium ion concentrations. The pattern of PLA2 inhibition by annexin‐I was consistent with a ‘specific interaction’ mechanism rather than the ‘substrate depletion’ model. Apparent contradiction with previous studies can be explained by the calcium‐dependent binding of annexin‐I to the substrate.
cDNA cloning and regional distribution of a novel member of the opioid receptor family
Authors: Fukuda Kazuhiko , Kato Shigehisa , Mori Kenjiro , Nishi Miyuki , Takeshima Hiroshi , Iwabe Naoyuki , Miyata Takashi , Houtani Takeshi , Sugimoto Tetsuo
Published: July 2002

We have cloned a cDNA for a novel member of the opioid receptor family, designated as ROR‐C, from the rat cerebrum cDNA library using the probe derived from the δ‐opioid receptor subtype cDNA. The deduced amino acid sequence of ROR‐C shows high homology with those of ROR‐A (rat δ‐opioid receptor subtype), ROR‐B (rat μ‐subtype) and ROR‐D (rat k‐subtype). RNA blot hybridization and in situ hybridization analysis revealed that ROR‐C mRNA is expressed in discrete regions of the rat central nervous system.
Limited diffusibility of gene products directed by a single nucleus in the cytoplasm of multinucleated myofibres
Authors: Ono Tomoko , Ono Katsuhiko , Mizukawa Kiminao , Ohta Tetsuya , Tsuchiya Tomofusa , Tsuda Masaaki
Published: July 2002

Two types of β‐galactosidase genes, whose products are distributed in the nucleus (Nα‐gal) or cytoplasm (Cβ‐gal), were injected with fructose intramuscularly into the quadriceps of adult mice. Regionally restricted and overlapped distributions of both gene products were observed in the myofibres. These findings indicate that Nβ‐gal is incorporated into the nucleus responsible for its synthesis and that Cβ‐gal becomes located in the vicinity of the nucleus after its synthesis. This restricted location of C β‐gal in myofibres remained unchanged during the development of infant mouse muscle. Thus, the gene products directed by the nucleus of myofibres seem to show limited diffusibility, suggesting a universal localization of subcellular domains in myofibres.
Presence of gene expression of vitamin D receptor and 24‐hydroxylase in OK cells
Authors: Ishimura Eiji , Shoji Shigeichi , Koyama Hidenori , Inaba Masaaki , Nishizawa Yoshiki , Morii Hirotoshi
Published: July 2002

We investigated the gene expression of 1,25‐dihydroxy‐vitamin D3 (1,25(OH)2D3) receptors (VDR) and 25‐hydroxy‐vitamin D3‐24‐hydroxylase (24‐hydroxylase) in opossum kidney (OK) cells. Reverse transcription‐polymerase chain reaction demonstrated the presence of VDR gene expression in OK cells. Northern hybridization, using rat VDR cDNA, also demonstrated a 4.4 kbp VDR mRNA expression which was affected by serum but not by 1,25(OH)2D3 and/or parathyroid hormone stimulation. Stimulation with 1,25(OH)2D3 induced 24‐hydroxylase mRNA expression which peaked at 6 h. This study clearly demonstrates for the first time the presence of VDR and 24‐hydroxylase gene expression in OK cells, suggesting that OK cells are a useful model for investigating the genetic action mechanisms of 1,25(OH)2D3.
Processing of prodynorphin by the prohormone convertase PC1 results in high molecular weight intermediate forms
Authors: Dupuy A. , Lindberg I. , Zhou Y. , Akil H. , Lazure C. , Chrétien M. , Seidah N.G. , Day R.
Published: July 2002

Processing of rat prodynorphin (proDyn) by the mouse prohormone convertase PCI was investigated. Recombinant vaccinia virus vectors were used to coexpress proDyn and PC1 in rat PC12 pheochromocytoma and mouse AtT‐20 corticotroph cells. In vitro experiments were also conducted by co‐incubating purified proDyn and PC1. The results demonstrate that PC1 cleaves proDyn at pairs of basic residues to yield 10 and 16 kDa high molecular weight (HMW) intermediates. Additionally, PC1 cleaves proDyn at a single arginine residue to yield an 8 kDa product and the C‐peptide. This demonstrates that PC1 cleaves proDyn at single and pairs of basic residues.
An extracellular residue determines the agonist specificity of V2 vasopressin receptors
Authors: Ufer Elke , Postina Rolf , Gorbulev Valentin , Fahrenholz Falk
Published: July 2002

The specific V2 agonist 1‐deamino [8‐d‐arginine]‐vasopressin (dDAVP), used for treatment of central diabetes insipidus, binds to vasopressin V2 receptors from human, bovine and rat kidney with an affinity that is similar to that of the natural hormone vasopressin. In contrast, the V1 receptors and the porcine V2 receptor do not tolerate a D‐arginine in position 8 of vasopressin. By site directed mutagenesis of the cloned bovine and porcine V2 receptors we identified a residue (Asp‐103) in the first extracellular loop of vasopressin receptors which is responsible for high affinity binding of dDAVP.
The psychosocial rehabilitation in Spain
Authors: Ballus C , Martí Tusquets JL
Published: July 2002

The future and present day state of psychosocial and sociobiological rehabilitation depends on scientific research, the differing rates of development within the autonomous communities, and the “administrative reform”. In the rehabilitation of the chronic mentally ill, these three factors complement existing psycho and sociobiological therapy and cognitive methodology training.
Introduction
Authors: Lopez-Ibor JJ
Published: July 2002

In the past serendipity and good clinical observation were essential for the discovery of new drug treatments for mental disorders. Today, neurochemical and pharmacological research allows development of compounds starting from hypothesis on the origin of the disorders and the actions of available drugs. The new compounds are cleaner from the pharmacological point of view, more specific and therefore with less undesired effects. Venlafaxine is one of these drugs and provides antidepressant efficacy in a broad range of depressed patients, including the most severe ones, with a good safety and tolerability profile.
Medicinal Chemical Biology
Authors: Jones Lyn H.
Published: April 2021

Arguably, the two most important decisions facing drug discovery teams are selecting the target and the therapeutic modality as the focus of their research efforts. This article highlights the recent technical advances in medicinal chemical biology that strongly influence these early, yet centrally important, choices. The article is not meant to be a comprehensive review of all innovations in the area. Examples are chosen that illustrate the impact chemical biology has had recently on drug discovery research. Medicinal chemical biology is ideally suited to expand druggable space through the development of target identification and validation technologies. Equally, innovative therapeutic modalities are required to enhance the medicinal toolkit to ensure that high‐quality clinical candidates are delivered that effectively target pathogenesis. Opportunities and challenges are described that serve to inspire further therapeutic research at the chemistry–biology interface.
Ex Situ Residual Stress Analysis of Chemical Vapor Deposited Diamond Coated Cutting Tools by Synchrotron X‐Ray Diffraction in Transmission Geometry
Authors: Hinzmann Daniel , Böttcher Katrin , Reimers Walter , Uhlmann Eckart
Published: April 2021

When machining difficult‐to‐cut, nonferrous materials, chemical vapor deposited (CVD) diamond–coated cutting tools are applied. The tools’ favorable mechanical property profile is based on the hardness of the coating as well as the adaptability of the substrate. Nevertheless, the reproducibility of machining results and process stability are limited by insufficient coating adhesion. The resulting cutting tool failure is based on coating delamination initiated by crack development. By assessing residual stress as an influence of coating adhesion, an analysis of CVD diamond–coated tools is performed using synchrotron X‐ray diffraction in transmission geometry. Investigation of a nanocrystalline and multilayer morphology on cobalt‐based tungsten carbide (WC‐Co) and a silicon nitride–based ceramic (Si3N4) provides the distribution of the principal in‐plane residual stress tensor component σ22 depending on the coating morphology and substrate material. Contrary to microcrystalline CVD diamond, nanocrystalline layers decrease the compressive residual stress. In addition, the CVD diamond coating deposited on the Si3N4 substrate material tends to induce an overall initial tensile residual stress that leads to increased tool performance compared to WC‐Co‐based coated tools. Variation of the coating morphology as well as the substrate material offers the possibility to extend the current model for residual stress–dependent tool failure.
Facing the Issues of Sheet Metal Equal‐Channel Angular Pressing: A Modified Approach Using Stacks to Produce Ultrafine‐Grained High Ductility AA5083 Sheets
Authors: Illgen Christian , Bohne Benjamin , Wagner Martin F.-X. , Gruber Maximilian , Volk Wolfram , Frint Philipp
Published: April 2021

A new approach for equal‐channel angular pressing (ECAP) of thin AA5083 sheets using two different orientations is investigated to address the issues of sheet metal ECAP. The method includes the deformation of a stack of 6 individual sheets supported by bulk material pieces placed on both sides of the stack. An excess length of the support materials and their pre‐deformation during an early stage of processing allows a buckling‐free deformation of the thin sheets for one of the investigated orientations. Multiple ECAP passes (up to N = 4) at room temperature following route C and microstructural analyses by electron back‐scatter diffraction are performed. Two passes of ECAP already result in considerable grain refinement with equiaxed grains, pronounced substructures and in an increased tensile strength at room temperature. At elevated temperatures (250 °C) a comparatively large elongation to failure (>130%) is found for the fine‐grained sheets. Diffusion‐controlled deformation mechanisms likely contribute to the deformation behavior of the investigated material. Scanning electron microscopy of the tensile specimens after testing reveals the formation of elongated and large cavities. These results highlight the suitability of the modified experimental method to produce (ultra)fine‐grained thin aluminum sheets with distinctly increased strength and ductility.
Renal‐Clearable Nickel‐Doped Carbon Dots with Boosted Photothermal Conversion Efficiency for Multimodal Imaging‐Guided Cancer Therapy in the Second Near‐Infrared Biowindow
Authors: Tian Boshi , Liu Shikai , Feng Lili , Liu Shaohua , Gai Shili , Dai Yunlu , Xie Lisi , Liu Bin , Yang Piaoping , Zhao Yanli
Published: April 2021

Photothermal agents with absorption in the second near‐infrared (NIR‐II) biowindow have attracted increasing attention for photothermal therapy (PTT) on account of their deeper tissue penetration capacity. However, most of the current NIR‐II photothermal agents exhibit low photothermal conversion efficiency (PCE) and long‐term biotoxicity. To overcome these shortcomings, herein, nickel and nitrogen co‐doped carbon dots (Ni‐CDs, ≈4.6 nm) are prepared via a facile one‐pot hydrothermal approach for imaging‐guided PTT in the NIR‐II window. The Ni‐CDs exhibit significant absorption in the NIR‐II region with a distinguished PCE as high as 76.1% (1064 nm) and have excellent photostability and biocompatibility. Furthermore, the Ni‐CDs can be employed as photothermal, photoacoustic, and magnetic resonance imaging contrast agents because of their outstanding photothermal effect and instinctive paramagnetic feature. The Ni‐CDs demonstrate significant PTT efficacy of tumor upon 1064 nm irradiation with a low power density (0.5 W cm−2). The Ni‐CDs can be eliminated from the body via a renal filtration pathway, thereby minimizing their long‐term biotoxicity. Therefore, this work provides a simple and feasible approach to develop photothermal agents with remarkable PCE in the NIR‐II region, presenting good biosafety for multimodal imaging‐guided PTT of tumor.
Bioinspired Tumor Calcification Enables Early Detection and Elimination of Lung Cancer
Authors: Wu Jicheng , Chen Yanni , Xin Jinxia , Qin Jiale , Zheng Weizeng , Feng Shuaishuai , Sun Chongran , Tian Mei , Lu Zhimin , Wang Ben
Published: April 2021

Precise diagnosis of cancer in an early stage and treatments with a reliable response, high selectivity, and negligible side effects is urgently needed. However, current cancer management involves low‐resolution metrics and delayed visual confirmation of tumor foci in imaging findings, and the toxicity of chemo‐ and radiotherapy unavoidably damages normal tissue and disrupts the immune balance of cancer patients. Here, a polypeptide is synthesized that preferentially targets lung cancer cells rather than normal lung epithelial cells and induces calcium precipitation specifically on the plasma membrane of lung cancer cells without additional supplementary calcium. Polypeptide‐induced cellular calcification can ideally facilitate medical imaging for identifying early‐stage lung cancer and distinguish cancer from benign nodules. Physiological and spontaneous calcification of tumors is induced by polypeptides and sharply prolongs the survival of tumor‐bearing mice without evidence of systemic side effects. This tumor cell‐selective calcification process provides an attractive, safe, and unprecedented approach for accurately visualizing and treating cancer in patients with early‐stage disease in the clinic. It has broad implications in developing simple physiological reactions for diagnosing and treating cancer and provides a new horizon for drug discovery.
Highly Efficient Air‐Mode Silicon Metasurfaces for Visible Light Operation Embedded in a Protective Silica Layer
Authors: Sun Qian , Liang Haowen , Zhang Jianchao , Feng Weibin , Martins Emiliano R. , Krauss Thomas F. , Li Juntao
Published: April 2021

Dielectric metasurfaces have significant potential for delivering miniaturized optical systems with versatile functionalities, leading to applications in various fields such as orbital angular momentum generation, imaging, and holography. Among the different materials, crystalline silicon has the advantage of technological maturity and high refractive index, which increases design flexibility and processing latitude. The second, and often overlooked, advantage of silicon is that it affords embedding the metasurface in a protective material such as silica, which is essential for practical applications. The trade‐off against this high refractive index is silicon's absorption at visible wavelength, which requires new design strategies. Here, such a strategy based on metasurfaces supporting air modes is identified that can lead to a transmission efficiency as high as 87% at a wavelength of 532 nm. This exceptional efficiency is obtained by using the high index to confine the electric field in the periphery of the meta‐atoms, thereby reducing absorption losses. As an example, the design of a fully embedded metasurface is described that can generate vortex beams with various orders of orbital angular momentum. It is envisioned that the proposed strategy paves the way for practical applications of high‐efficiency metasurfaces based on crystalline silicon.
Free H‐Bonding Interaction Sites in Rigid‐Chain Polymers and Their Filling Approach: A Molecular Dynamics Simulation Study
Authors: Yang Cheng , Xu Ruopei , Tang Siyi , Zhuang Yongbing , Luo Longbo , Liu Xiangyang
Published: April 2021

Hydrogen bond (H‐bond) plays an important role in structure evolution and properties of various polymers. Due to directivity and saturation of H‐bond, its formation is influenced by macromolecular chain conformation but the relationship is still not well understood up to now. In this paper, amorphous models of polyamide 66 (PA66), polyamide 6T (PA6T), and poly(p‐phenylene‐terephthamide) (PPTA) are built to study influence of chain rigidity on H‐bonding formation by utilizing Molecular Dynamics simulation. Compared with PA66 and PA6T, it is found that chain rigidity of PPTA is more remarkable and corresponding conformation adjustment is hindered more significantly, which leads to considerable weak H‐bonds and free H‐bonding sites. After introducing benzimidazole moiety into PPTA, more H‐bonds form due to more potential H‐bonding sites in benzimidazole units. However, the newly added H‐bonding donor and acceptor are in the co‐ring, and there is a high rotational energy barrier for benzimidazole ring, both of which hinder the formation of strong H‐bonds. Therefore, a strategy is proposed to fill free H‐bonding sites in rigid‐chain polymers through adding oligomers with high movement ability. Thus, the H‐bonds in rigid‐chain polymers are effectively enhanced due to bridging effect of oligomers and tensile modulus of the aramid is improved significantly.
Synergized Multimetal Oxides with Amorphous/Crystalline Heterostructure as Efficient Electrocatalysts for Lithium–Oxygen Batteries
Authors: Sun Zhihui , Cao Xuecheng , Tian Meng , Zeng Kai , Jiang Yongxiang , Rummeli Mark H. , Strasser Peter , Yang Ruizhi
Published: April 2021

High theoretical specific energy of rechargeable lithium–oxygen (Li–O2) batteries makes them very promising in the development of long driving range electric vehicles and energy storage on large‐scale. However, the large polarization and poor cycling stability associated with insufficient catalytic cathodes and the insulating nature of discharge products limit their practical applications. Here, the fabrication of a trimetallic CoFeCe oxide with an amorphous/crystalline heterostructure acting as an electrocatalyst for the Li–O2 battery cathode is reported. The best‐performing CoFeCe oxide cathode manages to deliver an initial discharge capacity of 12 340 mAh g−1, while maintaining an impressively enhanced cyclic stability over 2900 h at 100 mA g−1. As revealed by combined experimental results and density functional theory (DFT) analysis, synergistic interaction between oxide components, amorphous–crystalline domains, unique heterostructure with minimized lattice mismatch, and the enhanced adsorption of the key intermediate LiO2 are critical factors in boosting the electrocatalytic activity of CoFeCe toward the formation of decomposable Li2O2. This work offers a new insight to rationally design and synthesize an effective multimetal oxide electrocatalyst for the Li–O2 battery cathode.
Organocatalytic Enantioselective Desymmetrization of Prochiral 2,2‐Disubstituted Cyclic 1,3‐Diones
Authors: Chegondi Rambabu , Patel Srilaxmi M. , Maurya Sundaram , Donthoju Ashok
Published: April 2021

Enantioselective desymmetrization of prochiral 1,3‐cyclodiketones is the most convenient and highly desired transformation to access densely functionalized, enantiomerically enriched scaffolds with multiple chiral centers. In recent years, organocatalysis has made significant progress in this research area along with other traditional metal‐ or enzyme‐catalyzed reactions. This mini‐review provides an overview of the recent developments in the domain of organocatalytic enantioselective desymmetrization along with a brief discussion about future perspectives.
Single‐Site vs. Cluster Catalysis in High Temperature Oxidations
Authors: Serna Pedro , Rodríguez‐Fernández Aida , Yacob Sara , Kliewer Christine , Moliner Manuel , Corma Avelino
Published: April 2021

The behavior of single Pt atoms and small Pt clusters was investigated for high‐temperature oxidations. The high stability of these molecular sites in CHA is a key to intrinsic structure–performance descriptions of elemental steps such as O2 dissociation, and subsequent oxidation catalysis. Subtle changes in the atomic structure of Pt are responsible for drastic changes in performance driven by specific gas/metal/support interactions. Whereas single Pt atoms and Pt clusters (> ca. 1 nm) are unable to activate, scramble, and desorb two O2 molecules at moderate T (200 °C), clusters <1 nm do so catalytically, but undergo oxidative fragmentation. Oxidation of alkanes at high T is attributed to stable single Pt atoms, and the C‐H cleavage is inferred to be rate‐determining and less sensitive to changes in metal nuclearity compared to its effect on O2 scrambling. In contrast, when combustion involves CO, catalysis is dominated by metal clusters, not single Pt atoms.
Molecular Origin of Blood‐Based Infrared Spectroscopic Fingerprints**
Authors: Voronina Liudmila , Leonardo Cristina , Mueller‐Reif Johannes B. , Geyer Philipp E. , Huber Marinus , Trubetskov Michael , Kepesidis Kosmas V. , Behr Jürgen , Mann Matthias , Krausz Ferenc , Žigman Mihaela
Published: April 2021

Infrared spectroscopy of liquid biopsies is a time‐ and cost‐effective approach that may advance biomedical diagnostics. However, the molecular nature of disease‐related changes of infrared molecular fingerprints (IMFs) remains poorly understood, impeding the method's applicability. Here we probe 148 human blood sera and reveal the origin of the variations in their IMFs. To that end, we supplemented infrared spectroscopy with biochemical fractionation and proteomic profiling, providing molecular information about serum composition. Using lung cancer as an example of a medical condition, we demonstrate that the disease‐related differences in IMFs are dominated by contributions from twelve highly abundant proteins—that, if used as a pattern, may be instrumental for detecting malignancy. Tying proteomic to spectral information and machine learning advances our understanding of the infrared spectra of liquid biopsies, a framework that could be applied to probing of any disease.
Human Oxygenase Variants Employing a Single Protein FeII Ligand Are Catalytically Active
Authors: Brasnett Amelia , Pfeffer Inga , Brewitz Lennart , Chowdhury Rasheduzzaman , Nakashima Yu , Tumber Anthony , McDonough Michael A. , Schofield Christopher J.
Published: April 2021

Aspartate/asparagine‐β‐hydroxylase (AspH) is a human 2‐oxoglutarate (2OG) and FeII oxygenase that catalyses C3 hydroxylations of aspartate/asparagine residues of epidermal growth factor‐like domains (EGFDs). Unusually, AspH employs two histidine residues to chelate FeII rather than the typical triad of two histidine and one glutamate/aspartate residue. We report kinetic, inhibition, and crystallographic studies concerning human AspH variants in which either of its FeII binding histidine residues are substituted for alanine. Both the H725A and, in particular, the H679A AspH variants retain substantial catalytic activity. Crystal structures clearly reveal metal‐ligation by only a single protein histidine ligand. The results have implications for the functional assignment of 2OG oxygenases and for the design of non‐protein biomimetic catalysts.
Amplified Interfacial Effect in an Atomically Dispersed RuOx‐on‐Pd 2D Inverse Nanocatalyst for High‐Performance Oxygen Reduction
Authors: Lyu Zixi , Zhang Xia‐Guang , Wang Yucheng , Liu Kai , Qiu Chunyu , Liao Xinyan , Yang Weihua , Xie Zhaoxiong , Xie Shuifen
Published: April 2021

Atomically dispersed oxide‐on‐metal inverse nanocatalysts provide a blueprint to amplify the strong oxide–metal interactions for heterocatalysis but remain a grand challenge in fabrication. Here we report a 2D inverse nanocatalyst, RuOx‐on‐Pd nanosheets, by in situ creating atomically dispersed RuOx/Pd interfaces densely on ultrathin Pd nanosheets via a one‐pot synthesis. The product displays unexpected performance toward the oxygen reduction reaction (ORR) in alkaline medium, which represents 8.0‐ and 22.4‐fold enhancement in mass activity compared to the state‐of‐the‐art Pt/C and Pd/C catalysts, respectively, showcasing an excellent Pt‐alternative cathode electrocatalyst for fuel cells and metal–air batteries. Density functional theory calculations validate that the RuOx/Pd interface can accumulate partial charge from the 2D Pd host and subtly change the adsorption configuration of O2 to facilitate the O−O bond cleavage. Meanwhile, the d‐band center of Pd nanosubstrates is effectively downshifted, realizing weakened oxygen binding strength.
Genetically Engineered Polypeptide Adhesive Coacervates for Surgical Applications
Authors: Sun Jing , Xiao Lingling , Li Bo , Zhao Kelu , Wang Zili , Zhou Yu , Ma Chao , Li Jingjing , Zhang Hongjie , Herrmann Andreas , Liu Kai
Published: April 2021

Adhesive hydrogels have been developed for wound healing applications. However, their adhesive performance is impaired dramatically due to their high swelling on wet tissues. To tackle this challenge, we fabricated a new type of non‐swelling protein adhesive for underwater and in vivo applications. In this soft material, the electrostatic complexation between supercharged polypeptides with oppositely charged surfactants containing 3,4‐dihydroxylphenylalanine or azobenzene moieties plays an important role for the formation of ultra‐strong adhesive coacervates. Remarkably, the adhesion capability is superior to commercial cyanoacrylate when tested in ambient conditions. Moreover, the adhesion is stronger than other reported protein‐based adhesives in underwater environment. The ex vivo and in vivo experiments demonstrate the persistent adhesive performance and outstanding behaviors for wound sealing and healing.
Probing Interfacial Electronic Effects on Single‐Molecule Adsorption Geometry and Electron Transport at Atomically Flat Surfaces
Authors: Yu Zhou , Xu Yu‐Xing , Su Jun‐Qing , Radjenovic Petar M. , Wang Ya‐Hao , Zheng Ju‐Fang , Teng Botao , Shao Yong , Zhou Xiao‐Shun , Li Jian‐Feng
Published: April 2021

Clarifying interfacial electronic effects on molecular adsorption is significant in many chemical and biochemical processes. Here, we used STM breaking junction and shell‐isolated nanoparticle‐enhanced Raman spectroscopy to probe electron transport and adsorption geometries of 4,4′‐bipyridine (4,4′‐BPY) at Au(111). Modifying the surface with 1‐butyl‐3‐methylimidazolium cation‐containing ionic liquids (ILs) decreases surface electron density and stabilizes a vertical orientation of pyridine through nitrogen atom σ‐bond interactions, resulting in uniform adsorption configurations for forming molecular junctions. Modulation from vertical, tilted, to flat, is achieved on adding water to ILs, leading to a new peak ascribed to CC stretching of adsorbed pyridyl ring and 316 % modulation of single‐molecule conductance. The dihedral angle between adsorbed pyridyl ring and surface decreases with increasing surface electronic density, enhancing electron donation from surface to pyridyl ring.
Sustainable Lithium‐Metal Battery Achieved by a Safe Electrolyte Based on Recyclable and Low‐Cost Molecular Sieve
Authors: Chang Zhi , Qiao Yu , Yang Huijun , Cao Xin , Zhu Xingyu , He Ping , Zhou Haoshen
Published: April 2021

As one typical clean‐energy technologies, lithium‐metal batteries, especially high‐energy‐density batteries which use concentrated electrolytes hold promising prospect for the development of a sustainable world. However, concentrated electrolytes with aggregative configurations were achieved at the expense of using extra dose of costly and environmental‐unfriendly salts/additives, which casts a shadow over the development of a sustainable world. Herein, without using any expensive salts/additives, we employed commercially‐available low‐cost and environmental‐friendly molecular sieves (zeolite) to sieve the solvation sheath of lithium ions of classic commercialized electrolyte (LiPF6‐EC/DMC), and resulting in a unique zeolite sieved electrolyte which was more aggregative than conventional concentrated electrolytes. Inspiringly, the new‐designed electrolyte exhibited largely enhanced anti‐oxidation stability under high‐voltage (4.6 volts) and elevated temperature (55 °C). NCM‐811//Li cells assembled with this electrolyte delivered ultra‐stable rechargeabilities (over 1000 cycles for half‐cell; 300 cycles for pouch‐cell). More importantly, sustainable NCM‐811//Li pouch‐cell with negligible capacity decay can also be obtained through using recyclable zeolite sieved electrolyte. This conceptually‐new way in preparing safe and highly‐efficient electrolyte by using low‐price molecular sieve would accelerate the development of high‐energy‐density lithium‐ion/lithium‐metal batteries.
Synthesis and characterization of PVC‐TFC hollow fibers for forward osmosis application
Authors: Al‐Musawy Wafaa Kh. , Al‐Furaiji Mustafa H. , Alsalhy Qusay F.
Published: April 2021

Forward osmosis (FO) is considered among the most encouraging water desalination processes as a result of its high performance and low energy demand. Thin‐film composite (TFC) hollow fibers (HF) were synthesized and examined in the FO process. Three different concentrations of polyvinyl chloride (PVC) support polymer were fabricated via the phase inversion technique. The polyamide layer was synthesized on the outer surface of the PVC‐HF substrate via interfacial polymerization (IP) reaction. To the best of our knowledge, PVC HF was used in this research for the first time as a support for TFC‐FO membranes. PVC HFs have high‐quality specifications that are expected to have outstanding performance in TFC‐FO applications, especially for water desalination. The obtained membranes were characterized using contact angle measurement, scanning electron microscopy, atomic force microscope and Fourier‐transform Infrared. The performance of the PVC‐TFC HF was examined in the FO under standard conditions. Results showed that the membrane fabricated with a lower concentration of PVC substrate exhibited higher water flux in comparison to the higher concentration PVC membrane. Changing the concentration of PVC from 15% to 18% reduced water flux from 25 to 13 L m−2 h−1; however, salt flux also decreased from 8 to 3 g m−2 h−1.
4D printed stereolithography printed plant‐based sustainable polymers: Preliminary investigation and optimization
Authors: Danish Mohd. , Vijay Anirudh P. , Karunakaran C. , Rajamohan Vasudevan , Mathew Arun Tom , Koziol Krzysztof , Thakur Vijay Kumar , Kannan C. , Balan A. S. S.
Published: April 2021

The increasing demand for applying shape memory polymer to tissue culture and biomedical engineering has opened up research opportunities in the field of 4D Printing. The biocompatibility of the scaffolds as a culture medium resulted in the use of plant‐based polymers to provide an ambient environment for the growth of cells. This research investigates the 4D printing of acrylated epoxidized soybean oil (AESO), a plant‐based shape polymer. The objective of the present work is to establish the relationship between the 4D printing parameters (laser power frequency and print speed) and different properties of the printed material viz. tensile stress, surface roughness, wettability, recovery time, strain fixity and glass transition temperature. The maximum fixity was about 85%, while the recovery time as low as 1.6 s. The print parameters are optimized using regression modeling and multi‐objective optimization techniques. The shape memory effect of the polymer is demonstrated by printing samples at the optimized conditions. Dynamic mechanical analysis is performed to evaluate the variation in the glass transition temperature of AESO at specific print parameters. The adoption of an optimal set of laser frequency and print speed is found to improve the properties of AESO, while built by micro stereolithography (micro‐SLA).
A Tetradentate Phosphonate Ligand‐based Ni‐MOF as a Support for Designing High‐performance Proton‐conducting Materials
Authors: Chakraborty Debabrata , Ghorai Arijit , Chowdhury Avik , Banerjee Susanta , Bhaumik Asim
Published: April 2021

Developing a robust metal‐organic framework (MOF) which facilitates proton hopping along the pore channels is very demanding in the context of fabricating an efficient proton‐conducting membrane for fuel cells. Herein, we report the synthesis of a novel tetradentate aromatic phosphonate ligand H8L (L=tetraphenylethylene tetraphosphonic acid) based Ni‐MOF, whose crystal structure has been solved from single‐crystal X‐ray diffraction. Ni‐MOF [Ni2(H4L)(H2O)9(C2H7SO)(C2H7NCO)] displays a monoclinic crystal structure with a space group of P 21/c, a=11.887 Å, b=34.148 Å, c=11.131 Å, α=γ=90°, β=103.374°, where a nickel‐hexahydrate moiety located inside the void space of the framework through several H‐bonding interactions. Upon treatment of the Ni‐MOF in different pH media as well as solvents, the framework remained unaltered, suggesting the presence of strong H‐bonding interactions in the framework. High framework stability of Ni‐MOF bearing H‐bonding interactions motivated us to explore this metal‐organic framework material as proton‐conducting medium after external proton doping. Due to the presence of a large number of H‐bonding interactions and the presence of water molecules in the framework we have carried out the doping of organic p‐toluenesulfonic acid (PTSA) and inorganic sulphuric acid (SA) in this Ni‐MOF and observed high proton conductivity of 5.28×10−2 S cm−1 at 90 °C and 98% relative humidity for the SA‐doped material. Enhancement of proton conductivity by proton doping under humid conditions suggested a very promising feature of this Ni‐MOF.
LC–MS/MS method for determination of seneciphylline and its metabolite, seneciphylline N‐oxide in rat plasma, and its application to a rat pharmacokinetic study
Authors: Long Feng , Ji Jie , Wang Xin , Wang Lili , Chen Ting
Published: April 2021

A rapid and sensitive ultra‐performance liquid chromatography‐tandem electrospray ionization mass spectrometry (UPLC‐ESI/MS) method was established and validated for simultaneous determination of seneciphylline and its main metabolite in rat plasma. The plasma sample was prepared by simple methanol‐mediated precipitation. Chromatographic separation was achieved within 3 min by gradient elution using acetonitrile and water containing 0.1% formic acid as mobile phase on a Waters ACQUITY BEH C18 column (100 × 2.1 mm, i.d. 1.7  μm). Quantitation was conducted in a positive multiple reaction monitoring mode. The linearity of the method was over the range of 1–1,000 ng/mL, with the lower limit of quantification of 1 ng/mL. The intra‐ and inter‐day precision and accuracy, extraction recovery, and matrix effect of analytes were within the acceptable limit. The analytes were stable during the process of sample collection, preparation, and analysis. The validated method was further applied to a pharmacokinetic study of seneciphylline in rats after oral and intravenous administration. The results revealed that seneciphylline was quickly absorbed into plasma (Tmax, 0.23–0.32 h) and reached the maximum concentration of 0.82–1.75 μg/mL after oral administration. Both seneciphylline and seneciphylline N‐oxide were eliminated from plasma quickly. The low system exposure (oral bioavailability, 5.43–10.31%) was related to the extensive metabolism in the liver and microflora.
Development of NanoBRET‐Binding Assays for FKBP‐Ligand Profiling in Living Cells
Authors: Gnatzy Monika T. , Geiger Thomas M. , Kuehn Angela , Gutfreund Niklas , Walz Michael , Kolos Jürgen M. , Hausch Felix
Published: April 2021

FK506‐binding proteins (FKBPs) are promising targets for a variety of disorders and infectious diseases. High FKBP occupancy is thought to be necessary for ligands to effectively compete with the endogenous intracellular functions of FKBPs. Here, we report the development of NanoBRET assays for the most prominent cytosolic FKBPs, FKBP12, 12.6, 51 and 52. These assays allowed rapid profiling of FKBP ligands for target engagement and selectivity in living cells. These assays confirmed the selectivity of SAFit‐type ligands for FKBP51 over FKBP52 but revealed a substantial offset for the intracellular activity of these ligands compared to bicyclic ligands or natural products. Our results stress the importance to control for intracellular FKBP occupancy and provide the assays to guide further FKBP ligand optimization.