bluuebunny/crossref_metadata_2025 huggingface dataset:
Deciphering the molecular mechanism and apoptosis underlying the in‐vitro and in‐vivo chemotherapeutic efficacy of vanadium luteolin complex in colon cancer
Authors: Roy Souvik , Chakraborty Tania
Published: March 2018

The present study is carried out to reveal the chemotherapeutic effects of vanadium luteolin complex against HT‐29 human colon carcinoma cell line and chemically induced rat colon carcinoma. Our investigation revealed that the vanadium luteolin complex induces apoptosis in HT‐29 cells in a dose‐dependent manner. Furthermore, the study also confirmed that the vanadium luteolin complex increased caspase‐3 and p53 expression whereas reduced the VEGF, mTOR, Akt expression, and induced DNA fragmentation in HT‐29 cells. The oral acute and sub‐acute toxicity and the DNA binding efficacy of the complex with CT‐DNA were investigated. The vanadium luteolin complex showed mortality at a dose of 120 mg/kg dose. The sub‐acute toxicity of the complex at the dose of 90 mg/kg presented an increased level of WBC count, total bilirubin, ALT, AST, ALP, creatinine, blood urea nitrogen, and decreased level of total protein compared with the control group. Histopathological alterations in kidney, liver, stomach, and lungs was observed at a dose of 90 mg/kg of the complex. The dose of 45 mg/kg of the complex was found to have better chemotherapeutic activity by significantly reducing the incidences of aberrant crypt foci formation, upregulation in the expression of p53 and Bax, and downregulation of the expression of Bcl2, and cell proliferation was found in the complex at a dose of 45 mg/kg. Our findings from the study support that the complex possesses a potential chemotherapeutic activity against colon cancer and was efficient in reducing aberrant crypt foci formation multiplicity, hyperplastic lesions in the colon tissues of rats by inducing apoptosis.

Significance

The present study demonstrates that the effect of vanadium‐luteolin complex in HT‐29 cells and dimethylhydrazine challenged rats, curtail cell proliferation through induction of apoptosis mediated via activation of the key proteins involved in the intrinsic pathway like p53, Bax, caspase‐3 and downregulating Bcl2, mTOR/Akt, angiogenic factor VEGF along with aberrant crypt foci formation multiplicity, and PCNA in the colon mucosa. Our combinatorial approach shows higher efficacy at considerably lower doses minimizing side effects. Insights into in‐vitro and in‐vivo results provide strong proof that low dose chemotherapeutic regimens can suppress, reverse, or delay the progression of colon cancer by modulating intrinsic apoptotic as well as antiangiogenic pathways.
Microarray Analysis of Oligosaccharide‐Mediated Multivalent Carbohydrate–Protein Interactions and Their Heterogeneity
Authors: Gade Madhuri , Alex Catherine , Leviatan Ben‐Arye Shani , Monteiro João T. , Yehuda Sharon , Lepenies Bernd , Padler‐Karavani Vered , Kikkeri Raghavendra
Published: March 2018

Carbohydrate–protein interactions (CPIs) are involved in a wide range of biological phenomena. Hence, the characterization and presentation of carbohydrate epitopes that closely mimic the natural environment is one of the long‐term goals of glycosciences. Inspired by the multivalency, heterogeneity and nature of carbohydrate ligand‐mediated interactions, we constructed a combinatorial library of mannose and galactose homo‐ and hetero‐glycodendrons to study CPIs. Microarray analysis of these glycodendrons with a wide range of biologically important plant and animal lectins revealed that oligosaccharide structures and heterogeneity interact with each other to alter binding preferences.
Facile One‐Step Assembly of Bona Fide SUMO Conjugates by Chemoenzymatic Ligation
Authors: Pawale Vijaykumar S. , Yadav Prity , Roy Rajendra P.
Published: March 2018

The post‐translational conjugation of the small ubiquitin‐like modifiers (SUMOs) to target proteins occurs through a complex machinery that involves sequential action of at least three enzymes. SUMOylation performs crucial regulatory functions in several cellular processes. The availability of well‐defined SUMO conjugates is necessary for untangling the mechanism of SUMOylation. However, assembly of homogeneous SUMO conjugates represents a challenge because of the multi‐step synthesis involved and the unwieldiness of the reconstituted biosynthetic systems. Here we describe a simple one‐step chemoenzymatic strategy for conjugating engineered SUMO (eSUMO) proteins to a prefabricated isopeptide‐linked SUMO target peptide. Notably, the eSUMOs were efficiently recognized by the enzymes of the SUMOylation machinery and the SUMO conjugates served as bona fide substrates for DeSUMOylating enzymes.
Duplex Healing of Selectively Thiolated Guanosine Mismatches through a Cd2+ Chemical Stimulus
Authors: Lunn Samantha M. L. , Hribesh Samira , Whitfield Colette J. , Hall Michael J. , Houlton Andrew , Bronowska Agnieszka K. , Tuite Eimer M. , Pike Andrew R.
Published: March 2018

The on‐column selective conversion of guanosine to thioguanosine (tG) yields modified oligomers that exhibit destabilisation over the fully complementary duplex. Restoration to a stabilised duplex is induced through thio‐directed Cd2+ coordination; a route for healing DNA damage. Short oligomers are G‐specifically thiolated through a modified on‐column protocol without the need for costly thioguanosine phosphoramidites. Addition of Cd2+ ions to a duplex containing a highly disrupted tG central mismatch sequence, 3′‐A6tG4T6‐5′, suggests a (tG)8Cd2 central coordination regime, resulting in increased base stacking and duplex stability. Equilibrium molecular dynamic calculations support the hypothesis of metal‐induced healing of the thiolated duplex. The 2 nm displacement of the central tG mismatched region is dramatically reduced after the addition of a chemical stimuli, Cd2+ ions, returning to a minimized fluctuational state comparable to the unmodified fully complementary oligomer.
Triplex Formation by Oligonucleotides Containing Organomercurated Base Moieties
Authors: Ukale Dattatraya Uttam , Lönnberg Tuomas
Published: March 2018

Homothymine oligonucleotides with a single 5‐mercuricytosine or 5‐mercuriuracil residue at their termini have been synthesized and their capacity to form triplexes has been examined with an extensive array of double‐helical targets. UV and circular dichroism (CD) melting experiments revealed the formation and thermal denaturation of pyrimidine⋅purine*pyrimidine‐type triple helices with all oligonucleotide combinations studied. Nearly all triplexes were destabilized upon mercuration of the 3′‐terminal residue of the triplex‐forming oligonucleotide, in all likelihood due to competing intramolecular HgII‐mediated base pairing. Two exceptions from this general pattern were, however, observed: 5‐mercuricytosine was stabilizing when placed opposite to a T⋅A or A⋅T base pair. The stabilization was further amplified in the presence of 2‐mercaptoethanol (but not hexanethiol, thiophenol or cysteine), suggesting a stabilizing interaction other than HgII‐mediated base pairing.
Impact of percutaneous femoral arteriotomy closure using the MANTATM device on vascular and bleeding complications after transcatheter aortic valve replacement
Authors: De Palma Rodney , Settergren Magnus , Rück Andreas , Linder Rikard , Saleh Nawzad
Published: March 2018

Objectives

To evaluate the feasibility of fully percutaneous closure using a novel collagen‐based vascular closure device after transfemoral aortic valve replacement (TAVR).

Background

TAVR is utilized increasingly for the treatment of severe symptomatic aortic stenosis. Vascular complications related to access and closure dominate the adverse event profile of the procedure despite progressively reducing arteriotomy caliber. The advent of a novel collagen‐based device (MANTATM) and preliminary data suggest this could be used as a routine percutaneous closure device.

Methods

A prospective observational study of unselected consecutive patients undergoing TAVR in a single center. Data were collected via hospital electronic records and the SWEDEHEART registry. The primary clinical outcome was closure success and time to hemostasis. Secondary outcomes included VARC‐2 defined major and minor vascular and bleeding complications within 30 days using suture‐based closure with Prostar‐XL within the same center.

Results

A consecutive cohort of 346 patients underwent TAVR via the transfemoral approach. Vascular closure with MANTATM was successful in all with a mean time to hemostasis of 42 sec (SD 115.5, range 0–600). The composite of all‐cause mortality and major complications related to the main access site was similar between the groups (1.1% vs 1.9%, P = .61). Major bleeding occurred less frequently with MANTA TM (1.1% vs 7.8%, P = .02).

Conclusion

The novel use of a collagen‐based vascular closure device for large caliber arteriotomy is feasible in an unselected population undergoing transfemoral TAVR and appears efficacious compared to percutaneous suture‐based closure. These data should prompt larger studies to evaluate efficacy and safety.
Effect of sodium alginate on the gelatinization and retrogradation properties of two tuber starches
Authors: Yu Zhen , Wang Yu‐Sheng , Chen Hai‐Hua , Li Qian‐Qian
Published: March 2018

Background and objectives

The inherent properties of native starches are undesirable for the industrial applications because of the high tendency of retrogradation. Tuber starches are widely used in starchy foods. However, the gelatinization and retrogradation properties of tuber starches are not much known. This study mainly investigated the gelatinization and retrogradation properties of two tuber starches, potato starch (PS) and sweet potato starch (SPS), with or without the addition of sodium alginate (AG), using rapid visco analyzer, texture analyzer, differential scanning calorimeter, dynamic rheometer, and X‐ray diffractometer. The AG‐starch mixture gel was stored at 4°C for 1–21 days.

Findings

The results showed that the addition of AG increased the gelatinization temperature of the two tuber starches, suggesting the gelatinization process was delayed by the addition of AG. The addition of AG obviously decreased the setback (SB) value, while increased the tanδ values of the two tuber starches. This suggested that addition of AG could retard the short‐term retrogradation of starch. AG also significantly reduced the gel firmness, retrogradation ratio, and relative crystallinity of the two tuber starch gels during storage, indicating that the long‐term retrogradation was retarded with the addition of AG. Meanwhile, the retrograded starch with or without the addition of AG showed B‐type crystallinity pattern. Although PS contains phosphate groups, AG exerted a similar effect on the retrogradation of PS and SPS.

Conclusions

Results suggest that the addition of AG could retard the retrogradation and delay the gelatinization process of the two tuber starches.

Significance and novelty

This result can provide available information about the interactions between negative polysaccharide and negative/neutral starch, which also can provide an effective method to retard the starch retrogradation.
A rare case of rectal perforation from an accidentally swallowed foreign body
Authors: Sposato Luigi Alessandro , Reddy Chinnappa
Published: March 2018

Key Clinical Message

Rectal foreign bodies are not an infrequent presentation and can cause a serious dilemma regarding extraction and management. Management is determined by the site of the injury, degree of fecal contamination, the hemodynamic status of the patient, and comorbidities. Intraperitoneal injuries require surgery in the form of either a primary repair or formal resection with or without diversion. Extraperitoneal perforations maybe managed with presacral drainage and antibiotics with or without diversion.
A typical atypical chronic myeloid leukemia
Authors: Gilioli Andrea , Paolini Ambra , Bonacorsi Goretta , Luppi Mario
Published: March 2018

Key Clinical Message

In the context of leukocytosis due to increased number of neutrophils and their precursors, with significant dysgranulopoiesis and no or minimal basophilia and no or minimal monocytosis, the typical feature of “clumped” chromatin, in irregularly coarse compacted nuclei, should lead to suspect the diagnosis of atypical chronic myeloid leukemia.
Frequent falls and confusion: recurrent hypoglycemia in a patient with tuberous sclerosis complex
Authors: Comninos Alexander N. , Yang Lisa , Abbara Ali , Dhillo Waljit S. , Bassett J.H. Duncan , Todd Jeannie F.
Published: March 2018

Key Clinical Message

Recurrent hypoglycemia is common, but its presentation is often insidious resulting in delays in diagnosis and significant morbidity. We describe a case of an insulinoma presenting with falls and confusion in a patient with tuberous sclerosis, demonstrating the importance of early hypoglycemia identification and a potential shared molecular pathogenesis.
Bilateral fibular hemimelia associated with hip dislocation and femoral head necrosis
Authors: Saghir Salahiddine , Bousbaa Hicham , Agadr Aomar
Published: March 2018

Key Clinical Message

We describe a case of association of congenital bone abnormalities. It will allow clinicians to look systematically for other skeletal malformations and teach them how to evaluate these cases for the first time. This early screening will enable appropriate treatment to avoid complications and to preserve functional prognosis.
Metastatic renal cell carcinoma presenting with melena
Authors: Sadhale Ashwini , Adike Abimbola , Lam‐Himlin Dora
Published: March 2018

Key Clinical Message

Renal cell carcinoma is a highly malignant neoplasm. Metastasis to the pancreas and gastrointestinal tract is rare. In this case report, we show images of metastatic renal cell carcinoma to the upper gastrointestinal tract in a patient who presented with melena.
Multiple Metal (Cu, Mn, Fe) Centered Species Simultaneously Combined Nitrogen‐doped Graphene as an Electrocatalyst for Oxygen Reduction in Alkaline and Neutral Solutions
Authors: Lu Lei , Fan Jiawei , Lei Wu , Ouyang Yu , Yao Di , Xia Xifeng , Hao Qingli
Published: March 2018

A new efficient composite catalyst (CuIMnFeIIIO/NG) for oxygen reduction reaction (ORR) in both alkaline and neutral media, is successfully prepared via a facile, clean, low‐cost and reproducible solvothermal method without any further treatments. The nanoparticles consisting of crystalline phases of Fe2O3, MnCO3 and amorphous Cu2O&MnxOy (CuIMnO), are anchored on nitrogen‐doping graphene (N/C atomic ratio up to 10.56 %), which offer various active sites toward ORR. The synergistic catalytic effect between these components affords excellent ORR performance with comparable onset potential and current density to commercial Pt/C in both pH‐situations, and a 4‐electron‐transfer path during oxygen reduction. Furthermore, comparative experiment results are discussed to describe the different degrees of ORR contribution in different medium from metal species and nitrogen doping. Meanwhile, superior methanol tolerance and high stability of CuIMnFeIIIO/NG can make it a promising alternative for expensive commercial Pt‐based electrocatalysts in corresponding alkaline and neutral fuel cells.
Graphitic Carbon‐NiCo Nanostructures as Efficient Non‐Precious‐Metal Electrocatalysts for the Oxygen Reduction Reaction
Authors: Sivanantham Arumugam , Shanmugam Sangaraju
Published: March 2018

Composites of graphitic carbon layers and transition metals or metal alloys have received considerable attention for use as non‐precious‐metal catalysts for ecofriendly energy devices. In this paper, we report graphitic carbon‐supported NiCo alloys (NiCo@GC) that function as non‐precious‐metal electrocatalysts for the oxygen reduction reaction under alkaline conditions. In particular, we examined the effect of the pyrolysis temperature on the oxygen reduction activity. The catalyst prepared at 600 °C provided an oxygen reduction half‐wave potential (E1/2) of 0.81 V – only 10 mV less than that of a commercial Pt/C catalyst (0.82 V) – with the transfer of almost four electrons. Structural and chemical studies indicated that the excellent activity and stability of the NiCo@GC catalysts resulted from the strong interactions between (and the combined effects of) the metal and the carbon, dictated by the annealing temperature.
Impact of Textural Properties of Mesoporous Porphyrinic Carbon Electrocatalysts on Oxygen Reduction Reaction Activity
Authors: Woo Jinwoo , Sa Young Jin , Kim Jae Hyung , Lee Hyun‐Wook , Pak Chanho , Joo Sang Hoon
Published: March 2018

Transition‐metal‐ and N‐codoped carbon (M−N/C) catalysts have shown great promise as alternatives to Pt‐based catalysts in the oxygen reduction reaction (ORR). The preparation of M−N/C catalysts by exploiting mesoporous silica templates is highly appealing as this method can generate catalysts with high surface areas, well‐developed porosities, and abundant active sites. Herein, we report the relationship between the textural properties of mesoporous silica‐templated Fe−N/C catalysts and their ORR activity. Iron‐doped mesoporous porphyrinic carbons (Fe−MPCs) with varying textural properties were synthesized through nanocasting using mesoporous silicas as the templates and Fe porphyrin as the precursor. Fe−MPC catalysts showed excellent ORR activities with half‐wave potentials reaching 0.82 V and 0.90 V (vs. reversible hydrogen electrode, RHE) in acidic and alkaline electrolytes, respectively. Fe−MPC catalysts with smaller particle sizes, larger mesopore sizes, and three dimensionally interconnected pore structures showed enhanced ORR activities.
Asphalt‐Derived Hierarchically Porous Carbon with Superior Electrode Properties for Capacitive Storage Devices
Authors: Song Xinyu , Ma Xinlong , Yu Zhiqing , Ning Guoqing , Li Yun , Sun Yuzhen
Published: March 2018

Active carbon with hierarchical pore structure (HPC) is prepared in mass using asphalt as carbon precursor by a template‐directed method. The as‐prepared HPC exhibits excellent capacitive energy‐storage capacities on a symmetric supercapacitor (140 F g−1 at 0.5 A g−1) and Li‐ion capacitor (LIC) using HPC as both cathode and anode (340 F g−1 at 0.5 A g−1), as well as long cyclability for a supercapacitor (no capacity loss after 15000 cycles) and LIC (91.3 % capacitance retention after 10000 cycles). The superior energy and power densities are 202 W kg−1 and 15398 Wh kg−1, respectively. The hierarchical pore structure in combination with the existence of heteroatoms originated from the carbon precursor ensure the conductivity for the delivery of electrolyte ions and electrons, greatly contributing to the high capacitance and the excellent cycle performance. This work provides a very promising opportunity for high‐capacitive energy storage devices by means of the high value‐added utilization of asphalt.
One‐Step Electrodeposition Method to Prepare Robust Flexible PEDOT‐Based Films for Ultra‐Stable Supercapacitors
Authors: Ye Guo , Zhu Danhua , Zhou Qianjie , Li Danqin , Zuo Yinxiu , Duan Xuemin , Zhou Weiqiang , Xu Jingkun
Published: March 2018

The front cover artwork is provided by Jiangxi Provincial Key Laboratory of Drug Design and Evaluation, School of Pharmacy Jiangxi Science and Technology Normal University (China). The image shows a robust flexible P(EDOT‐co‐BEDTH) film with an ultra‐stable cyclic life, demonstrating 99% retention after 30 000 cycles, which makes it suitable for practical application in all‐solid‐state supercapacitors. Read the full text of the Article at 10.1002/celc.201800099.
Hierarchical Porous Carbons Derived from Renewable Poplar Anthers for High‐Performance Supercapacitors
Authors: Song Jian , Shen Wenzhong , Wang Jianguo , Fan Weibin
Published: March 2018

Hierarchical porous carbons with granular shape were prepared from waste biomass poplar anthers (PA) by pre‐carbonization and following KOH activation. The pore structure and surface chemistry of PA‐derived carbon can be controlled by adjusting the activation temperature. The material activated at 800 °C possesses a high surface area of 3639 m2 g−1, abundant mesopores, and appropriate amounts of oxygen‐ and nitrogen‐containing species. As a result, it exhibits excellent electrochemical performances as a supercapacitor electrode. The specific capacitance reaches 361.5 F g−1 at a current density of 0.5 A g−1 in 6 M KOH aqueous solution. In addition, it shows an impressive energy density of 60.8 Wh kg−1 at a power density of 10416.7 W kg−1 in the ionic liquid BMIMBF4. Particularly, a high electrochemical stability and an excellent reversibility were observed in both aqueous and non‐aqueous electrolytes.
Ruthenium‐Catalyzed Selective C−C Coupling of Allylic Alcohols with Free Indoles: Influence of the Metal Catalyst
Authors: Xia Ying‐Qi , Li Chao , Liu Man , Dong Lin
Published: March 2018

Versatile reactive activities of allyl alcohols with free indoles in C−H functionalization reactions were investigated. Direct alkylation or cascade cyclization reactions could be selectively controlled based on the catalyst system: Ru(PPh3)3Cl2 provided C3‐substituted β‐ketone indoles whereas [Ru(p‐cymene)Cl2]2 yielded cyclized indoles.
Surface‐Doped Polystyrene Microsensors Containing Lipophilic Solvatochromic Dye Transducers
Authors: Wang Lu , Xie Xiaojiang , Cao Tianchi , Bosset Jérôme , Bakker Eric
Published: March 2018

Ion‐selective optical microsensors based on surface‐modified polystyrene (PS) beads with positively charged lipophilic solvatochromic dye (SD) on the surface were studied with K+ as model ion. Water‐soluble SDs are expelled into the aqueous phase by ion exchange with the cationic analyte of interest, resulting in a detectable color change. In contrast, lipophilic SDs are more attractive, as they appear to remain anchored to the surface after expulsion from the sensing phase. This transfers just the ionic chromophore functionality into the aqueous phase and allows the system to act as a reversible, truly self‐contained sensor. In this work this mechanism was evaluated with ζ‐potential measurements on microsensor suspensions. It indeed provides experimental evidence for the mechanism of SD transfer, as a reversal of the ζ‐potential of the PS microsensors was observed for higher potassium concentrations with valinomycin‐doped microspheres. For a discriminated ion such as sodium, the ζ‐potential change occurs at much higher electrolyte concentrations, in agreement with sensor selectivity. Undoped microspheres showed no apparent dependence of ζ‐potential on electrolyte concentration. The study also shows that the effective range of microsensor surface charge is tunable and depends on the concentration of the SD on the coating phase.
The Generation of Diazo Compounds in Continuous‐Flow
Authors: Hock Katharina J. , Koenigs Rene M.
Published: March 2018

Toxic, cancerogenic and explosive—these attributes are typically associated with diazo compounds. Nonetheless, diazo compounds are nowadays a highly demanded class of reagents for organic synthesis, yet the concerns with regards to safe and scalable transformations of these compounds are still exceptionally high. Lately, the research area of the continuous‐flow synthesis of diazo compounds attracted significant interest and a whole variety of protocols for their “on‐demand” preparation have been realized to date. This concept article focuses on the recent developments using continuous‐flow technologies to access diazo compounds; thus minimizing risks and hazards when working with this particular class of compounds. In this article we discuss these concepts and highlight different pre‐requisites to access and to perform downstream functionalization reaction.
Magnetic Interactions through a Nonconjugated Framework Observed in Back‐to‐Back Connected Triazinyl–Nitroxyl Biradical Derivatives
Authors: Takahashi Yusuke , Matsuhashi Ryo , Miura Youhei , Yoshioka Naoki
Published: March 2018

Three hetero‐biradical derivatives, with the structure of a back‐to‐back connected benzotriazinyl and tetramethyl or tetraethylisoindoline N‐oxyl sharing a common benzo ring, 3‐tert‐butyl‐1‐phenyl‐1,4,6,8‐tetrahydro‐6,6,8,8‐tetramethyl‐pyrrolo[4,5‐g]‐1,2,4‐benzotriazin‐4‐yl‐7‐oxyl (1‐tBu), 1,3‐diphenyl‐1,4,6,8‐tetrahydro‐6,6,8,8‐tetramethyl‐pyrrolo[4,5‐g]‐1,2,4‐benzotriazin‐4‐yl‐7‐oxyl (1‐Ph), and 3‐tert‐butyl‐1‐phenyl‐1,4,6,8‐tetrahydro‐6,6,8,8‐tetraethyl‐pyrrolo[4,5‐g]‐1,2,4‐benzotriazin‐4‐yl‐7‐oxyl (2‐tBu), were synthesized and characterized by single‐crystal X‐ray analyses, variable‐temperature magnetic susceptibility studies, and DFT calculations. Temperature dependences of the magnetic susceptibilities of 1‐tBu, 1‐Ph, and 2‐tBu exhibit broad maxima at 70, 71, and 43 K, respectively. Although these radical derivatives form a columnar or chained assembly in the solid state, magnetic measurements of diluted samples in the polymer matrices and computational results imply that the magnetic properties of the polycrystalline sample can be explained by a two‐spin system with an intramolecular antiferromagnetic interaction. The magnetic behavior can be reproduced by using the Bleaney–Bowers model, with 2J=−80.0 cm−1 for 1‐tBu, 2J=−77.1 cm−1 for 1‐Ph, and 2J=−48.9 cm−1 for 2‐tBu. The moderately strong intramolecular antiferromagnetic interactions can be interpreted by a through‐bond interaction through the nonconjugated framework and/or through‐space interactions based on molecular orbital theory. The strong distance dependency between the N−O spin site and vinylic carbon atoms indicates that the orbital interaction plays an important role in the intramolecular magnetic interaction. The reduced magnetic interaction in 2‐tBu relative to those of 1‐tBu and 1‐Ph can be attributed to restricted rotation of the tetraethyl group.
3 D Porous CoS2 Hexadecahedron Derived from MOC toward Ultrafast and Long‐Lifespan Lithium Storage
Authors: Wang Han‐Chi , Cui Zheng , Fan Chao‐Ying , Liu Si‐Yu , Shi Yan‐Hong , Wu Xing‐Long , Zhang Jing‐Ping
Published: March 2018

A new hexadecahedron assembled by core–shell CoS2 particles@N‐doped carbon (CoS2@NCH) is prepared successfully through the self‐templating method. The CoS2@NCH hybrid electrode delivers a high lithium‐storage capacity of 778 mA h g−1 after 1000 cycles at a high current density of 1 A g−1, which is the longest cycle lifespan among the reported CoS2 anode materials in lithium‐ion batteries. Furthermore, the CoS2@NCH hybrid electrode shows excellent rate capability with a discharge capacity of 220 mA h g−1 at an extremely high current density of 20 A g−1, and a charge capacity of 649 mA h g−1 is restored upon returning the current density back to 2 A g−1. The superior performance is attributed to the unique construction of CoS2@NCH. The N‐doped interconnected porous carbon shells form highly conductive skeletons for quick electron transfer and prevent the electrode from collapsing. Moreover, the porous characteristic of the materials plays a key role: as some effective channels, the mesopores on the porous carbon shells provide greater access for lithium, and the mesopores derived from the particle interspace enables the complete immersion of the electrodes in electrolyte, which alleviates the volume expansion and ensures the integrity of the electrode. In addition, the nanosized CoS2 particles, which shorten the ion‐transport path and provide extra electroactive sites, also improve the reaction kinetics.
Nitrogen‐Functionalized Hydrothermal Carbon Materials by Using Urotropine as the Nitrogen Precursor
Authors: Straten Jan Willem , Schleker Philipp , Krasowska Małgorzata , Veroutis Emmanouil , Granwehr Josef , Auer Alexander A. , Hetaba Walid , Becker Sylvia , Schlögl Robert , Heumann Saskia
Published: March 2018

Nitrogen‐containing hydrothermal carbon (N‐HTC) materials of spherical particle morphology were prepared by means of hydrothermal synthesis with glucose and urotropine as precursors. The molar ratio of glucose to urotropine has been varied to achieve a continuous increase in nitrogen content. By raising the ratio of urotropine to glucose, a maximal nitrogen fraction of about 19 wt % could be obtained. Decomposition products of both glucose and urotropine react with each other; this opens up a variety of possible reaction pathways. The pH has a pronounced effect on the reaction pathway of the corresponding reaction steps. For the first time, a comprehensive analytical investigation, comprising a multitude of analytical tools and instruments, of a series of nitrogen‐containing HTC materials was applied. Functional groups and structural motifs identified were analyzed by means of FTIR spectroscopy, thermogravimetric MS, and solid‐state NMR spectroscopy. Information on reaction mechanisms and structural details were obtained by electronic structure calculations that were compared with vibrational spectra of polyfuran or polypyrrole‐like groups, which represent structural motifs occurring in the present samples.
Diquats with Robust Chirality: Facile Resolution, Synthesis of Chiral Dyes, and Application as Selectors in Chiral Analysis
Authors: Talele Harish R. , Koval Dušan , Severa Lukáš , Reyes‐Gutiérrez Paul E. , Císařová Ivana , Sázelová Petra , Šaman David , Bednárová Lucie , Kašička Václav , Teplý Filip
Published: March 2018

Diquats with extremely high racemization barriers with ΔG≠theor of 233 kJ mol−1 at 180 °C are described. Reported configurational robustness is due to a combination of two structural features: the rigid o‐xylylene tether connecting the nitrogen atoms and the presence of two substituents in the bay region of the bipyridinium scaffold. The straightforward synthesis of diquats, plus facile resolution and derivatization make them attractive for chiral application studies. This is demonstrated by: 1) synthesis of the first non‐racemic diquat dyes with pronounced chiroptical properties, and 2) capability of diquats to interact stereospecifically with chiral molecules. This suggests potential for diquat derivatives to be used as chiral selectors in separation methods.
Photocatalysis with Quantum Dots and Visible Light for Effective Organic Synthesis
Authors: Huang Cheng , Li Xu‐Bing , Tung Chen‐Ho , Wu Li‐Zhu
Published: March 2018

Colloidal semiconductor quantum dots (QDs) have recently attracted widespread interest for diverse applications. Owing to their quantum confinement effects, rich surface binding properties, high surface‐to‐volume ratios, broad and intense absorption spectra in the visible region, and low cost as well, QDs offer new and versatile ways to serve as photocatalysts for organic synthesis. Most recently, the use of QDs photocatalysts is springing up in organic synthesis. Herein, we highlight the recent advances of QDs used for smart and clean organic transformations.
A Multifaceted Study of Methane Adsorption in Metal–Organic Frameworks by Using Three Complementary Techniques
Authors: Zhang Yue , Lucier Bryan E. G. , Fischer Michael , Gan Zhehong , Boyle Paul D. , Desveaux Bligh , Huang Yining
Published: March 2018

Methane is a promising clean and inexpensive energy alternative to traditional fossil fuels, however, its low volumetric energy density at ambient conditions has made devising viable, efficient methane storage systems very challenging. Metal–organic frameworks (MOFs) are promising candidates for methane storage. In order to improve the methane storage capacity of MOFs, a better understanding of the methane adsorption, mobility, and host–guest interactions within MOFs must be realized. In this study, methane adsorption within α‐Mg3(HCO2)6, α‐Zn3(HCO2)6, SIFSIX‐3‐Zn, and M‐MOF‐74 (M=Mg, Zn, Ni, Co) has been comprehensively examined. Single‐crystal X‐ray diffraction (SCXRD) experiments and DFT calculations of the methane adsorption locations were performed for α‐Mg3(HCO2)6, α‐Zn3(HCO2)6, and SIFSIX‐3‐Zn. The SCXRD thermal ellipsoids indicate that methane possesses significant mobility at the adsorption sites in each system. 2H solid‐state NMR (SSNMR) experiments targeting deuterated CH3D guests in α‐Mg3(HCO2)6, α‐Zn3(HCO2)6, SIFSIX‐3‐Zn, and MOF‐74 yield an interesting finding: the 2H SSNMR spectra of methane adsorbed in these MOFs are significantly influenced by the chemical shielding anisotropy in addition to the quadrupolar interaction. The chemical shielding anisotropy contribution is likely due mainly to the nuclear independent chemical shift effect on the MOF surfaces. In addition, the 2H SSNMR results and DFT calculations strongly indicate that the methane adsorption strength is linked to the MOF pore size and that dispersive forces are responsible for the methane adsorption in these systems. This work lays a very promising foundation for future studies of methane adsorption locations and dynamics within adsorbent MOF materials.
Enantioselective Synthesis of 5,5‐Disubstituted Hydantoins by Brønsted Base/H‐Bond Catalyst Assisted Michael Reactions of a Design Template
Authors: Izquierdo Joseba , Etxabe Julen , Duñabeitia Eider , Landa Aitor , Oiarbide Mikel , Palomo Claudio
Published: March 2018

A new method for the enantioselective synthesis of 5,5‐disubstituted (quaternary) hydantoins was developed on the basis of an organocatalytic Michael reaction approach involving the use of 2‐benzylthio‐3,5‐dihydroimidazol‐4‐ones as key hydantoin surrogates. The method is general with respect to the substitution pattern at the hydantoin N1 (alkyl, aryl, acyl), N3 (aryl), and C5 (linear/branched alkyl, aryl) positions and affords essentially single diastereomeric products with enantioselectivities higher than 95 % ee in most cases. Among the bifunctional Brønsted base/H‐bond catalysts examined, a known squaramide–tertiary amine catalyst and a newly prepared squaramide–tertiary amine catalyst provide the highest selectivity so far with either nitroolefins or vinyl ketones as the acceptor components. Kinetic measurements support a first‐order rate dependence on both reaction partners, the donor template and the Michael acceptor, whereas competitive 1H NMR spectroscopy experiments reveal the high ability of the template for catalyst binding.
Polyacrylonitrile‐Derived Sponge‐Like Micro/Macroporous Carbon for Selective CO2 Separation
Authors: Guo Li‐Ping , Hu Qing‐Tao , Zhang Peng , Li Wen‐Cui , Lu An‐Hui
Published: March 2018

CO2 capture under a dynamical flow situation requires adsorbents possessing balanced proportion of macropores as diffusion path and micropores as adsorption reservoir. However, the construction of interconnected micro‐/macropores structure coupled with abundant nitrogen species into one carbon skeleton remains a challenge. Here, we report a new approach to prepare sponge‐like carbon with a well‐developed micro‐/macroporous structure and enriched nitrogen species through aqueous phase polymerization of acrylonitrile in the presence of graphene oxide. The tension stress caused by the uniform thermal shrinkage of polyacrylonitrile during the pyrolysis together with the favorable flexibility of graphene oxide sheets are responsible for the formation of the sponge‐like morphology. The synergistic effect of micro‐/macroporous framework and rich CO2‐philic site enables such carbon to decrease resistance to mass transfer and show high CO2 dynamic selectivity over N2 (454) and CH4 (11), as well as good CO2 capacity at 298 K under low CO2 partial pressure (0.17 bar, a typical CO2 partial pressure in flue gas). The above attributes make this porous carbon a promising candidate for CO2 capture from flue gas, methane sources and other relevant applications.
Towards Useful Boronates through Atom‐Economical Catalyzed Cascade Reactions
Authors: Buñuel Elena , Cárdenas Diego J.
Published: March 2018

Metal‐catalyzed borylative cyclization reactions of polyunsaturated compounds allow concomitant formation of C−C and C−B bonds to provide cyclic boronates, which constitute synthetically useful intermediates. Recent developments using first‐row transition metals as catalysts provide fully atom‐economical reactions that follow mechanisms involving σ‐bond metathesis.
The Expanding Utility of Rhodium‐Iminocarbenes: Recent Advances in the Synthesis of Natural Products and Related Scaffolds
Authors: Li Yun , Yang Hongjian , Zhai Hongbin
Published: March 2018

Rhodium‐iminocarbenes that are derived from N‐sulfonyl‐1,2,3‐triazoles have become an important class of reactive species and useful intermediates in organic synthesis. Over the last several years, many practical and versatile approaches involving rhodium‐iminocarbene intermediates to synthetically challenging molecules (scaffolds) have been developed. This Minireview mainly summarizes the recent advance of rhodium‐iminocarbene involved reactions in the synthesis of natural products and their related scaffolds by the end of 2017. Several applications in important pharmaceuticals are documented as well.
Optical Sensing of Aromatic Amino Acids and Dipeptides by a Crown‐Ether‐Functionalized Perylene Bisimide Fluorophore
Authors: Weißenstein Annike , Saha‐Möller Chantu R. , Würthner Frank
Published: March 2018

The host–guest binding properties of a fluorescent perylene bisimide (PBI) receptor equipped with crown ether were studied in detail with a series of aromatic amino acids and dipeptides by UV/Vis, fluorescence and NMR spectroscopy. Fluorescence titration experiments showed that electron‐rich aromatic amino acids and dipeptides strongly quench the fluorescence of the electron‐poor PBI host molecule. Benesi–Hildebrand plots of fluorescence titration data confirmed the formation of host–guest complexes with 1:2 stoichiometry. Binding constants determined by global analysis of UV/Vis and fluorescence titration experiments revealed values between 103 m−1 and 105 m−1 in acetonitrile/methanol (9:1) at 23 °C. These data showed that amino acid l‐Trp having an indole group and dipeptides containing this amino acid bind to the PBI receptor more strongly than other amino acids and dipeptides investigated here. For dipeptides containing l‐Trp or l‐Tyr, the binding strength is dependent on the distance between the ammonium group and the aromatic unit of the amino acids and dipeptides leading to a strong sensitivity for Ala‐Trp dipeptide. 1D and 2D NMR experiments also corroborated 1:2 host–guest complexation and indicated formation of two diastereomeric species of host–guest complexes. The studies have shown that a properly functionalized PBI fluorophore functions as a molecular probe for the optical sensing of aromatic amino acids and dipeptides.
Sr[BeSi2N4]:Eu2+/Ce3+ and Eu[BeSi2N4]: Nontypical Luminescence in Highly Condensed Nitridoberyllosilicates
Authors: Strobel Philipp , Weiler Volker , Schmidt Peter J. , Schnick Wolfgang
Published: March 2018

M[BeSi2N4] (M=Sr,Eu), crystallizing in the hexagonal space group P
2c, was synthesized from Sr(NH2)2, Be3N2, and “Si(NH)2” in W crucibles under a N2 atmosphere in a radio‐frequency furnace. The crystal structure was solved from powder X‐ray diffraction data by the charge‐flipping method (Sr[BeSi2N4]: a=4.86082(2), c=9.42264(4) Å, Z=2; Eu[BeSi2N4]: a=4.85848(1), c=9.41615(4) Å). M[BeSi2N4] contains a highly condensed rigid network of trigonal planar [BeN3] units that are connected to Si2N7 double tetrahedra by common vertices. M[BeSi2N4] (M=Sr,Eu) are the first examples of nitridoberyllosilicates and are isotypic to the oxoberyllate Sr[Be3O4]. Eu2+‐doped Sr[BeSi2N4] and Eu[BeSi2N4] show orange‐trapped exciton emission (λem=605 nm, fwhm ≈126 nm), whereas Ce3+‐doped samples of Sr[BeSi2N4] show nontypical yellowish‐orange luminescence. Sr[BeSi2N4] has a large band gap of ≈4.4 eV and shows high chemical and thermal stability. Eu2+‐doped beryllates with regular 4f65d1→4f7‐emission could be interesting for future application in LEDs upon doping with Eu2+ or Ce3+ due to large band gaps, rigid networks, and chemical and thermal stability.
Coumarin/BODIPY Hybridisation for Ratiometric Sensing of Intracellular Polarity Oscillation
Authors: Bai Yang , Shi Xiangchao , Chen Yuncong , Zhu Chengcheng , Jiao Yang , Han Zhong , He Weijiang , Guo Zijian
Published: March 2018

With different polarity responses, coumarin and 4,4‐difluoro‐4‐bora‐3a,4a‐diaza‐s‐indacene (BODIPY) were hybridised to construct polarity fluorescent sensors, CBDP and iso‐CBDP, to overcome the disadvantages of solvatochromic sensors in ratiometric polarity sensing. Only CBDP displayed an emission ratio (ICou/IBDP, coumarin to BODIPY emissions) that increased with an exponential dependence on medium relative permittivity over a wide polarity range (ϵr<57.9). This sensing ability of CBDP was not affected by medium pH; viscosity; and most intracellular species, especially reactive oxygen, nitrogen, and sulfur species. Apart from local cytoplasmic polarity quantification through lambda imaging, CBDP enables real‐time ratiometric imaging for intracellular polarity oscillation induced by oxidative stimulation. Ratiometric polarity flow cytometry was developed, for the first time, with CBDP, which demonstrated that a high concentration H2O2 induced cytoplasmic polarity enhancement, whereas pre‐incubation with N‐acetyl‐l‐cysteine inhibited this effect.
Enantioselective Catalyst Systems from Copper(II) Triflate and BINOL–Silanediol
Authors: Guan Yong , Attard Jonathan W. , Visco Michael D. , Fisher Thomas J. , Mattson Anita E.
Published: March 2018

Silanediol and copper catalysis are merged, for the first time, to create an enhanced Lewis acid catalyst system for enantioselective heterocycle functionalization. The promise of this silanediol and copper catalyst combination is demonstrated in the enantioselective addition of indoles to alkylidene malonates to give rise to the desirable adducts in excellent yield and high enantiomeric excess. From these studies, 1,1′‐bi‐2‐naphthol (BINOL)‐based silanediols emerge as one‐of‐a‐kind cocatalysts. Their potential role in the reaction pathway is also discussed.
Catalytic Hydrodefluorination of C−F Bonds by an Air‐Stable PIII Lewis Acid
Authors: Chitnis Saurabh S. , Krischer Felix , Stephan Douglas W.
Published: March 2018

Catalytic hydrodefluorination (HDF) of unactivated fluoroalkanes or CF3‐substituted aryl species is performed using the PIII Lewis acids, [(bipy)PPh]2+ (12+) and [(terpy)PPh]2+ (22+) under mild conditions (25 or 50 °C). Mechanistic studies indicate that activation of C−F bond by the PIII center is key. Particularly noteworthy is that the catalyst 2[B(C6F5)4]2 is air‐stable and readily accessible from bench‐stable, commercially available reagents in one‐step and can be used without isolation.
Amino acids as chiral derivatizing agents for antiproliferative substituted N‐benzyl isoindolinones
Authors: Grigoreva Tatyana A. , Novikova Daria S. , Gureev Maxim A. , Garabadzhiu Alexander V. , Tribulovich Vyacheslav G.
Published: March 2018

The absolute configurations of the diastereomers of novel amino acid ester derivatives of 2,3‐substituted isoindolinones, which are known as apoptosis activators due to their ability to inhibit the MDM2‐p53 PPI, were assigned using NMR and computational methods. Procedures for diastereomer separation and determining the absolute configuration were developed to perform the study. The high significance of N‐benzyl fragment for the determination of the diastereomer absolute configuration by NMR methods was established; it is determined by a number of factors inherent in this fragment and the structural features of the studied substrates. Analysis of the individual isomer activity showed that the target inhibitory effect of S‐ and R‐isoindolinone L‐valinates differs by less than 20%. It can be explained by the presence of a flexible linker between the isoindolinone core and amino acid fragment, which provides the optimal arrangement of the molecule in the hydrophobic cavity of MDM2 for both isomers.
Process Control and Yield Enhancement of the Galacto‐Oligosaccharide Formation
Authors: Mueller Ines , Kiedorf Gregor , Runne Eike , Pottratz Ines , Seidel‐Morgenstern Andreas , Hamel Christof
Published: March 2018

As lactose is an increasing by‐product of dairy industry, the selective conversion to prebiotic galacto‐oligosaccharides (GOSs) by the enzyme β‐galactosidase represents a highly attractive value creation. The synthesis of GOSs is characterized by an equilibrium‐limited reaction, which can be overcome by a coupling with an enzymatic reduction of the side product glucose to achieve an increase in product yield. Furthermore, the effect of substrate substitution based on sweet whey and the impact of whey‐dominating salt ions was examined, leading to a further process intensification of GOS synthesis.
Modeling and Design of a Catalytic Wall Reactor for the Methanation of Carbon Dioxide
Authors: Gruber Manuel , Wieland Christoph , Habisreuther Peter , Trimis Dimosthenis , Schollenberger Dominik , Bajohr Siegfried , vonMorstein Olaf , Schirrmeister Steffen
Published: March 2018

Microprocess engineering is an alternative approach to design reactors for CO2 methanation, which are used in power‐to‐gas applications. Microreactors offer advantages, e.g., in terms of heat removal. In the present work, design criteria evolved from transport phenomena are applied to derive preliminary reactor dimensions. The developed 1D model is used for parametric studies and reveals heat transport as limiting factor. More detailed 3D models confirm the results and demonstrate the effect of the metal matrix on heat transport. For further optimization a multi‐stage reactor design is proposed.
Abwarten und Bärentraubenblätter‐Tee trinken – mit Arbutin
Authors: Dietrich Corinna , Munzert Viola , Zeller Klaus‐Peter , Siehl Hans‐Ullrich , Berger Stefan , Sicker Dieter
Published: March 2018

Die Blätter der Echten Bärentraube enthalten das Hydrochinon‐Glucosid Arbutin. Als Prodrug wird es erst im Körper zu einer pharmakologisch wirksamen Substanz metabolisiert, dem Aglykon Hydrochinon. Daher wirkt ein Bärentraubenblätter‐Kaltauszug als Hausmittel gegen einfache Formen der Blasenentzündung. Weniger bekannt ist, dass Arbutin auch in Kosmetika gegen Hyperpigmentierungs‐Störungen der Haut angewendet wird. Arbutin wurde frühzeitig strukturell aufgeklärt und synthetisiert. Wir beschreiben seine Isolierung und interpretieren den gesamten Spektrensatz als Musterbeispiel für ein einfaches β‐D‐Glucosid. Dieser Beitrag basiert auf einer Bachelorarbeit.
Dynamic control of arabinose and xylose utilization inE. coli
Authors: Choudhury Debika , Gayen Kalyan , Saini Supreet
Published: March 2018

The common bacteriumEscherichia coli(E. coli) can utilize the pentose sugars arabinose and xylose for growth and energy. When fed both these sugars, the bacterium preferentially utilizes arabinose and only when all the arabinose is exhausted from the media does it start to use xylose. This hierarchical utilization of the two sugars is dictated by two proteins: AraC and XylR. These proteins act as controllers of sugar utilization and dictate the timing and rate of utilization of these sugars. While the biochemical interactions defining individual arabinose and xylose utilization systems are well understood, it is not completely understood how the hierarchical utilization is maintained by the bacterium, and how the regulatory crosstalk between the two systems facilitates this hierarchy. To help answer these questions, in this work, we systematically experimentally characterize the regulatory crosstalk between the two sugar utilization systems.

Our work demonstrates extensive interaction between the two sugar systems. Specifically, data from our experiments suggest that the xylose system can regulate arabinose gene expression and consequently, cellular physiology dynamically via promiscuous transport and maybe through cross interactions between regulator and non‐cognate sugar. Put together, we demonstrate that arabinose and xylose utilization networks exhibit an example of distributed control in a biological system. This design likely ensures that the system does not fail under perturbations (mutations). Our results help understand multi‐process control in biological systems and bring to light design criteria for synthetic biology applications.