bluuebunny/crossref_metadata_2025 huggingface dataset:
Reinforcement Learning Algorithm for Load Balancing in Self‐Organizing Networks
Authors: Ali Mohammed S. , Coucheney Pierre , Coupechoux Marceau
Published: May 2020

Self‐Organized Networks (SON) are a crucial feature to make 5G more efficient in 3GPP Release 16. 5G SON inherits from LTE self‐configuration, self‐optimization, and self‐healing functions, and also expands to new use cases and relies on a service‐based architecture and data analytics network functions. SON algorithms are, however, not part of the standard. In this article, we thus present a novel reinforcement learning approach for distributed load balancing in heterogeneous networks that use cell range expansion for user association and Almost Blank Subframe (ABS) for interference management. We model the interactions among the base stations for load balancing as a near‐potential game. Using the proposed distributed learning algorithms, players reach an optimal Pure Nash Equilibrium (PNE). We provide sufficient conditions under which the learning algorithms converge to the optimal PNE. By running extensive simulations, we show that the proposed algorithms converge within few hundreds of iterations. Finally, we show that outage can be controlled and a better load balancing can be achieved by introducing ABS.
MECand Cloud Security
Authors: Ding Aaron Yi
Published: May 2020

Security is crucial for 5G mobile systems. As multi‐access edge computing (MEC) and cloud technologies are going to be utilized by 5G to support various services including Internet of Things (IoT), health, smart grid, and transportation, there is a strong demand for comprehensive investigation of the security aspects of MEC and cloud in 5G context. The core security concerns for 5G MEC and cloud include trust on hardware components and connected devices, system software, networking and communication, micro‐edge service, and distributed security logging at scale. Besides the discussion of threat models and challenges, four promising research directions are also highlighted, covering trust management, machine learning‐based security enforcement, microservice management, and hardware‐assisted security enhancement in 5G networks. The illustrations focus on current security challenges and corresponding solutions for 5G MEC and cloud. The analysis and outlook shed light on future 5G security development and integration of MEC and cloud technologies. The content is of special interest to 5G engineers, researchers, service developers, and policy makers from industry, academia, and government.
Big Data/Machine Learning andD2D
Authors: Althamary Ibrahim , Huang Chih‐Wei
Published: May 2020

Recently, big data, machine learning, and D2D communication have gained more attention to support the growth of data traffic and novel applications. The objective of this article is to present critical technology elements and show how new researches move forward to justify user requirements. In particular, D2D communication and vehicular networks can take advantage of the knowledge extracted using machine learning tools from collected data for better understanding and decision. Furthermore, emerging multi‐agent reinforcement learning is highlighted to be a suitable tool with high potential. Finally, several research opportunities and challenges are addressed.
5G
‐Service‐Based Architecture
Authors: Chandramouli Devaki , Gkellas Georgios
Published: May 2020

This article explains 5G System Architecture and the key architectural principles. It also explains in detail the two main building blocks of the 5GC control plane: service‐based architecture and compute–storage split for facilitating resiliency/scalability in 5G system, and their salient characteristics.
Wireline–Wireless Convergence
Authors: Thiébaut Laurent , Bouchat Christele
Published: May 2020

Virtualization and the development of the 5G architecture, i.e. a 5GCore (5GC) capable to serve a great variety of Access Networks have triggered the industry to work on Wireless–Wireline convergence. As opposed to previous attempts that were focusing on convergence at policy control level, the 5GC‐based solution focuses on defining an interworking function, the Wireline Access Gateway Function (W‐AGF), that terminates the legacy Wireline Access interface on one of its sides and the 5GC interfaces N1/N2/N3 on its other side.

This architecture enables the 5GC to serve Residential Gateways modified to support 5G protocols and procedures (5G RG) but also legacy unmodified Fixed Network Residential Gateways (FN RG).

5G RG can benefit of slicing as defined for 5GC but also of a Hybrid Access where 5G RG are simultaneously connected via 3GPP radio and via Wireline Access, ensuring thus higher throughput and reliability for the traffic of the customer premises.

Fixed Wireless Access (5G RG connection via 3GPP radio) enables flexible deployment of a mobile RG (e.g. in public transport or for short‐lived events).

A 5G RG and its Wireline Access interworking function, the W‐AGF, can together be used as a trusted non‐3GPP AN serving 3GPP User Equipment (smartphone) with managed Quality of Service and accurate location information (e.g. for home‐based charging).

The Broadband Forum (BBF) and 3GPP deliver a first release of the corresponding specifications for March 2020 (3GPP R16) that will likely be improved in the next release (3GPP R17).
Development Challenges of Millimeter‐Wave 5G Beamformers
Authors: Abbasi Muhammad Ali Babar , Abbasi Qammer H.
Published: May 2020

Beamforming is the central concept that can make millimeter‐wave (mmWave) a viable solution by solving challenges of link‐budget, cost, power, form factor, complexity, regulatory constraint, and so on. Before deployment of mmWave beamforming solution for 5G, and possibly beyond, several fundamental questions need to be answered. Some of them include hardware constraints, performance matrices, realistic propagation channel models including impairments due to obstacles such as body, blockages due to casings, phase noise, a model for spatial‐temporal variations in channels, and advanced MIMO techniques for multi‐carrier and multiuser communications. The site constraints and massive non‐line‐of‐sight transmission within the urban environment are severely questioning the conventional terrestrial low power node deployments that used to work well at low operational frequencies (sub‐6 GHz). In addition to this, in beamforming technology using massive antenna arrays, the coordination of the users and beams at the transmitter and receiver end within a large network are very challenging. In this article, we comprehensively investigate some of the most prominent and best practice solutions that attempted to answer these challenging questions.
Authentication and Access Control for5G
Authors: Behrad Shanay , Bertin Emmanuel , Crespi Noel
Published: May 2020

The fifth generation of mobile cellular networks, 5G, is designed to support a set of new use cases and requirements that affect every aspects of human life. Therefore, the security in 5G systems becomes more important than the security in any other pre‐5G networks. Authenticating users and controlling their access to network services is one of the first procedures to provide the security requirements of the system. Since 3G, the main authentication and access control procedures in cellular networks are based on Authentication and Key‐Agreement (AKA) protocols. In addition to study the weaknesses of the authentication and access control procedures in the pre‐5G networks, it is crucial to consider the 5G new use cases and requirements in designing authentication and access control mechanisms for 5G. In this article, we study the 5G network architecture considering the network functions involved in the authentication and access control processes. Then, we review the vulnerabilities of the 5G‐AKA protocol, which is the main authentication and access control mechanism in 5G. Finally, we study the new use cases in 5G and depict that they have different security requirements and consequently they need different authentication and access control mechanisms.
User Association in5GNetworks: A Game‐Theoretic Approach
Authors: Eliodorou Michalis , Psomas Constantinos , Krikidis Ioannis
Published: May 2020

In future fifth generation (5G) and beyond wireless technologies, ultra‐dense networks (UDNs) will be employed to serve a massive number of devices with mobile access. One of the major challenges in UDNs is user association, which is essential for dealing with intra‐ and intercell interference. In this work, we investigate two user association problems aiming to optimize two different network parameters and solve them via a game‐theoretical approach. Specifically, the effectiveness of coalitional games is shown in this work through the form of coalition game algorithms for resource allocation.
Immune‐mediated axonal dysfunction in seropositive and seronegative primary Sjögren’s syndrome
Authors: Tani Jowy , Liao Hsien‐Tzung , Hsu Hui‐Ching , Chen Lung‐Fang , Chang Tsui‐San , Shin‐Yi Lin Cindy , Sung Jia‐Ying
Published: May 2020

Objective

The present study investigates the peripheral neuropathy in Primary Sjögren's syndrome (pSS) using the nerve excitability test to further elucidate how peripheral nerves are affected by the autoantibodies.

Methods

Each patient received clinical evaluation, examination for anti‐SSA/Ro and anti‐SSB/La antibodies titer, paired motor and sensory nerve excitability test, thermal quantitative sensory test (QST), and nerve conduction study (NCS).

Results

A total of 40 pSS patients wasenrolled. Motor axonal study of the pSS with positive anti‐SSA/Ro or anti‐SSB/La antibodies (n = 28) was found to have increased stimulus for 50% compound muscle action potential (CMAP) (P < 0.05), increased rheobase (P < 0.01), increased minimum I/V slope (P < 0.01) and hyperpolarizing I/V slope (P < 0.05), increased relative refractory period (RRP, P < 0.001), decreased accommodation of threshold electrotonus toward depolarizing current (P < 0.05), and increased accommodation toward hyperpolarizing current (P < 0.05). Seronegative pSS (n = 10) showed much less prominent motor axonal changes, showing only increased minimum I/V slope (P < 0.05). Sensory axonal study in seropositive pSS patients is found to have increased stimulus for 50% sensory nerve action potential (SNAP) (P < 0.01), decreased latency (P < 0.01), increased RRP (P < 0.01), and increased subexcitability (P < 0.05). Seronegative pSS patients have shown no significant sensory axonal changes. Thermal QST showed more prominent abnormalities in seronegative pSS compared to seropositive pSS.

Interpretation

Anti‐SSA/Ro and anti‐SSB/La autoantibodies might cause dysfunction in nodal and internodal region of the axon and small nerve fibers; meanwhile, autoreactive antibodies in seronegative pSS mainly affect small nerve fibers. Thus, the underlying pathophysiology for the two types of pSS is different.
Proposed bill for HEROES Act would give $1.5 billion to SAPT block grant
Authors: Knopf Alison
Published: May 2020

With the House of Representatives planning to vote last Friday on the fourth COVID‐19 stimulus package, substance use treatment stands a chance of being included — if the Senate, which at press time was still opposing the measure, as was the White House, goes ahead to approve it as well. The Health and Economic Recovery Omnibus Emergency Solutions (HEROES) Act, for about $2 trillion, would finally give some money to states, counties and health care. So far, more than $2 trillion has been spent on stimulus funding, with the field trying hard to be included in each bill (see “NASADAD requests $250 million for Phase 4 stimulus,” ADAW April 13, https://onlinelibrary.wiley.com/doi/10.1002/adaw.32688).
Survey offers clues for initiating buprenorphine in emergency settings
Authors: Enos Gary
Published: May 2020

In interpreting the results of research, readers always should take note of the time period in which data was collected, given the typical lag between when studies are conducted and when results are released. This is a key message from authors of a study published last week that showed minimal readiness among emergency physicians to initiate buprenorphine treatment in the emergency department (ED). The authors report that these results informed initiatives within surveyed physicians' academic medical center sites, which now have demonstrated rapid progress in implementing buprenorphine in the ED.
College students, sexual activity, and binge drinking
Authors: Knopf Alison
Published: May 2020

College is a time when some young people start to drink, or drink more and have sex more. The peak age range for binge drinking is 18–25. But in college, sexual activity is also starting for many.
Endo/Lysosome‐Escapable Delivery Depot for Improving BBB Transcytosis and Neuron Targeted Therapy of Alzheimer's Disease
Authors: Cai Lulu , Yang Chuanyao , Jia Wenfeng , Liu Yuwei , Xie Rou , Lei Ting , Yang Zhihang , He Xueqin , Tong Rongsheng , Gao Huile
Published: May 2020

The effective treatment of Alzheimer's disease (AD) is hindered due to the hard blood–brain barrier (BBB) penetration and non‐selective distribution of drugs in the brain. Moreover, the complicated pathological mechanism of AD involves various pathway dysfunctions that limit the effectiveness of a single therapeutic drug. Herein, a dendrigraft poly‐l‐lysines (DGL)‐based siRNA and D peptide (Dp) loaded nanoparticle is designed that could target and penetrate through the BBB, enter the brain parenchyma, and further accumulate at the AD lesion. In this system, T7 peptide, which specifically targets transferrin receptors on the BBB, is linked to DGL via acid‐cleavable long polyethylene glycol (PEG) to achieve high internalization, quick escape from endo/lysosome, and effective transcytosis. Then, the Tet1, which specifically targets diseased neurons, is modified onto DGL by short PEG. After being exposed, Tet1 could drive the nanoparticles to the AD lesion and release the drugs. As a result, the production of β amyloid plaques (Aβ) is inhibited. Neurotoxicity induced by Aβ plaques and tau proten phosphorylation (p‐tau) tangle is also alleviated, and the cognition of AD mice is significantly improved. Overall, this system programmatically targets BBB and neurons, thus, significantly enhances the intracephalic drug accumulation and AD treatment efficacy.
Laboratory studies on dissolution of nitrogen fertilizers by humidity and precipitation
Authors: Sigtryggsson Christian , Hamnér Karin , Kirchmann Holger
Published: May 2020

Aiming at improving fertilizer management by assessing fertilizer dissolution, we compared the hygroscopicity of calcium ammonium nitrate (CAN), ammonium nitrate (NS 27‐4), and nitrate compounds (laboratory grade). Dissolution of N fertilizers was also studied under simulated rain conditions. All compounds were highly hygroscopic, dissolving within 24 h at 90–99% relative humidity and 25 °C. Addition of 2 mm rain to fertilizer granules (3–4.5 mm diam.) was sufficient to dissolve 50% of the compounds. Dissolution rates by humidity or rain were not the limiting step for plant availability.
Recent Advances in Vanadium‐Based Aqueous Rechargeable Zinc‐Ion Batteries
Authors: Liu Shude , Kang Ling , Kim Jong Min , Chun Young Tea , Zhang Jian , Jun Seong Chan
Published: May 2020

Aqueous zinc‐ion batteries (AZIBs) have attracted considerable attention as promising next‐generation power sources because of the abundance, low cost, eco‐friendliness, and high security of Zn resources. Recently, vanadium‐based materials as cathodes in AZIBs have gained interest owing to their rich electrochemical interaction with Zn2+ and high theoretical capacity. However, existing AZIBs are still far from meeting commercial requirements. This article summarizes recent advances in the rational design of vanadium‐based materials toward AZIBs. In particular, it highlights various tactics that have been reported to increase the intercalation space, structural stability, and the diffusion ability of the guest Zn2+, as well as explores the structure‐dependent electrochemical performance and the corresponding energy storage mechanism. Furthermore, this article summarizes recent achievements in the optimization of aqueous electrolytes and Zn anodes to resolve the issues that remain with Zn anodes, including dendrite formation, passivation, corrosion, and the low coulombic efficiency of plating/stripping. The rationalization of these research findings can guide further investigations in the design of cathode/anode materials and electrolytes for next‐generation AZIBs.
Demand response scheduling under uncertainty: Chance‐constrained framework and application to an air separation unit
Authors: Kelley Morgan T. , Baldick Ross , Baldea Michael
Published: May 2020

Recent increases in renewable power generation challenge the operation of the power grid: generation rates fluctuate in time and are not synchronized with power demand fluctuations. Demand response (DR) consists of adjusting user electricity demand to match available power supply. Chemical plants are appealing candidates for DR programs; they offer large, concentrated loads that can be modulated via production scheduling. Price‐based DR is a common means of engaging industrial entities; its benefits increase significantly when a longer (typically, a few days) scheduling time horizon is considered. DR production scheduling comes with its own challenges, related to uncertainty in future (i.e., forecast) electricity prices and product demand. In this work, we provide a framework for DR production scheduling under uncertainty based on a chance‐constrained formulation that also accounts for the dynamics of the production facility. The ideas are illustrated with an air separation unit case study.
Gonadal dysfunction and beyond: Clinical challenges in children, adolescents, and adults with 47,XXY Klinefelter syndrome
Authors: Zitzmann Michael , Rohayem Julia
Published: May 2020

Klinefelter syndrome (KS) is the most frequent sex chromosomal aneuploidy. The karyotype 47,XXY originates from either paternal or maternal meiotic nondisjunction during gametogenesis. KS males are very likely to exhibit marked gonadal dysfunctions, presenting both in severely attenuated spermatogenesis as well as hypergonadotropic hypogonadism. In addition, neurocognitive and psychosocial impairments, as well as cardiovascular, metabolic and bone disorders are often found in KS and might explain for an increased morbidity/mortality. All conditions in KS are likely to be induced by both gene overdosage effects resulting from supernumerary X‐chromosomal genes as well as testosterone deficiency. Notwithstanding, the clinical features are highly variable between KS men. Symptoms can become obvious at infancy, childhood, or adolescence. However, the majority of KS subjects is diagnosed during adulthood. KS adolescents require specific attention regarding pubertal development, in order to exploit their remaining fertility potential and allow for timely and tailored testosterone replacement. The chances for sperm retrieval might decline with age and could be hampered by testosterone replacement; therefore, cryostorage of spermatozoa is an option during adolescence, before the decompensation of endocrine and exocrine testicular functions becomes more overt. Sperm from semen or surgically retrieved, in combination with intracytoplasmic sperm injection enables KS males to become biological fathers of healthy children. The aim of this article is to present the current knowledge on KS, to guide clinical care and to highlight research needs.
Neuropsychological functions, sleep, and mental health in adults with Klinefelter syndrome
Authors: Fjermestad Krister W. , Huster Rene , Thunberg Christina , Stokke Simen , Gravholt Claus H. , Solbakk Anne‐Kristin
Published: May 2020

A few studies have examined neuropsychological functions, sleep, and mental health combined in Klinefelter syndrome (KS; 47,XXY). We investigated neuropsychological functions with standard tests, sleep with actigraphy, and self‐reported mental health in 30 men with KS (Mean age = 36.7 years) compared to 21 controls (Mean age = 36.8 years). Men with KS scored significantly lower on mental speed, attention span, working memory, inhibition, and set‐shifting tests, as well as overall IQ (mean effect size difference Cohen's d = 0.79). Men with KS had significantly longer night wakes, with no differences in other sleep variables (mean d = 0.34). Men with KS reported poorer mental health than controls (mean d = 1.16). Regression analyses showed neuropsychological functions explained variance in some sleep domains for men with KS but not for controls. Neuropsychological functions explained variance in some mental health domains for controls. For men with KS, however, verbal IQ was the only significant predictor of mental health. Altogether, men with KS display problems in neuropsychological functions and mental health but do not appear different from controls on most sleep parameters. Our findings indicate that relations between neuropsychological functions, sleep, and mental health differ between men with KS and controls.
Kalium‐Polyheptazinimid: Ein übergangsmetallfreier Festkörper‐Triplett‐Sensibilisator in Kaskadenenergietransfer und [3+2]‐Cycloadditionen
Authors: Savateev Aleksandr , Tarakina Nadezda V. , Strauss Volker , Hussain Tanveer , ten Brummelhuis Katharina , Sánchez Vadillo José Manuel , Markushyna Yevheniia , Mazzanti Stefano , Tyutyunnik Alexander P. , Walczak Ralf , Oschatz Martin , Guldi Dirk M. , Karton Amir , Antonietti Markus
Published: May 2020

Polymere Kohlenstoffnitridmaterialien wurden erfolgreich in zahlreichen Anwendungen zur Umwandlung von Licht in Energie, die von der Photokatalyse bis zur Optoelektronik reichen, eingesetzt. Für eine neue Anwendung und Modellierung verfeinerten wir zunächst die Kristallstruktur von Kalium‐Polyheptazinimid (K‐PHI) – einem Referenz‐Kohlenstoffnitridmaterial in der Photokatalyse – mithilfe von Röntgenpulverdiffraktometrie und Transmissionselektronenmikroskopie. Unter Verwendung der Kristallstruktur von K‐PHI wurden periodische DFT‐Berechnungen durchgeführt, um die Zustandsdichte zu berechnen und Intra‐Banden‐Zustände (IBS) zu lokalisieren. Es wurde festgestellt, dass IBS für die erhöhte Absorption von K‐PHI im nahen IR‐Bereich verantwortlich sind, als Elektronenfallen dienen und bei Energietransferreaktionen nützlich sind. Einmal mit sichtbarem Licht angeregt, können Kohlenstoffnitride neben der direkten Rekombination auch Intersystem Crossing vom Singulett‐ in den Triplett‐Zustand durchlaufen. Wir nutzen die angeregten zentrierten Triplett‐Zustände im K‐PHI, um eine Kaskade von Energieübertragungsreaktionen auszulösen und im Gegenzug z. B. Singulett‐Sauerstoff (1O2), als Ausgangspunkt für die Synthese von bis zu 25 verschiedenen N‐reichen Heterozyklen, zu sensibilisieren.
TiCl3‐Mediated Synthesis of 2,3,3‐Trisubstituted Indolenines: Total Synthesis of (+)‐1,2‐Dehydroaspidospermidine, (+)‐Condyfoline, and (−)‐Tubifoline
Authors: Delayre Bastien , Piemontesi Cyril , Wang Qian , Zhu Jieping
Published: May 2020

2,3,3‐Trisubstituted indolenine constitutes an integral part of many biologically important monoterpene indole alkaloids. We report herein an unprecedented access to this skeleton by a TiCl3‐mediated reductive cyclization of tetrasubstituted alkenes bearing a 2‐nitrophenyl substituent. The proof of concept is demonstrated firstly by accomplishing a concise total synthesis of (+)‐1,2‐dehydroaspidospermidine featuring a late‐stage application of this key transformation. A sequence of reduction of nitroarene to nitrosoarene followed by 6π‐electron‐5‐atom electrocyclization and a 1,2‐alkyl shift of the resulting nitrone intermediate was proposed to account for the reaction outcome. A subsequent total synthesis of (+)‐condyfoline not only illustrates the generality of the reaction, but also provides a mechanistic insight into the nature of the 1,2‐alkyl shift. The exclusive formation of (+)‐condyfoline indicates that the 1,2‐alkyl migration follows a concerted Wagner–Meerwein pathway, rather than a stepwise retro‐Mannich/Mannich reaction sequence. Conditions for almost quantitative conversion of (+)‐condyfoline to (−)‐tubifoline by way of a retro‐Mannich/1,3‐prototropy/transannular cyclization cascade are also documented.
Lead‐Free Halide Double Perovskite Cs2AgBiBr6 with Decreased Band Gap
Authors: Ji Fuxiang , Klarbring Johan , Wang Feng , Ning Weihua , Wang Linqin , Yin Chunyang , Figueroa José Silvestre Mendoza , Christensen Christian Kolle , Etter Martin , Ederth Thomas , Sun Licheng , Simak Sergei I. , Abrikosov Igor A. , Gao Feng
Published: May 2020

Environmentally friendly halide double perovskites with improved stability are regarded as a promising alternative to lead halide perovskites. The benchmark double perovskite, Cs2AgBiBr6, shows attractive optical and electronic features, making it promising for high‐efficiency optoelectronic devices. However, the large band gap limits its further applications, especially for photovoltaics. Herein, we develop a novel crystal‐engineering strategy to significantly decrease the band gap by approximately 0.26 eV, reaching the smallest reported band gap of 1.72 eV for Cs2AgBiBr6 under ambient conditions. The band‐gap narrowing is confirmed by both absorption and photoluminescence measurements. Our first‐principles calculations indicate that enhanced Ag–Bi disorder has a large impact on the band structure and decreases the band gap, providing a possible explanation of the observed band‐gap narrowing effect. This work provides new insights for achieving lead‐free double perovskites with suitable band gaps for optoelectronic applications.
Phosphonate‐Modified UiO‐66 Brønsted Acid Catalyst and Its Use in Dehydra‐Decyclization of 2‐Methyltetrahydrofuran to Pentadienes
Authors: Dorneles de Mello Matheus , Kumar Gaurav , Tabassum Tarnuma , Jain Sheetal K. , Chen Tso‐Hsuan , Caratzoulas Stavros , Li Xinyu , Vlachos Dionisios G. , Han Songi‐I , Scott Susannah L. , Dauenhauer Paul , Tsapatsis Michael
Published: May 2020

Phosphorus‐modified all‐silica zeolites exhibit activity and selectivity in certain Brønsted acid catalyzed reactions for biomass conversion. In an effort to achieve similar performance with catalysts having well‐defined sites, we report the incorporation of Brønsted acidity to metal–organic frameworks with the UiO‐66 topology, achieved by attaching phosphonic acid to the 1,4‐benzenedicarboxylate ligand and using it to form UiO‐66‐PO3H2 by post‐synthesis modification. Characterization reveals that UiO‐66‐PO3H2 retains stability similar to UiO‐66, and exhibits weak Brønsted acidity, as demonstrated by titrations, alcohol dehydration, and dehydra‐decyclization of 2‐methyltetrahydrofuran (2‐MTHF). For the later reaction, the reported catalyst exhibits site‐time yields and selectivity approaching that of phosphoric acid on all‐silica zeolites. Using solid‐state NMR and deprotonation energy calculations, the chemical environments of P and the corresponding acidities are determined.
Real‐Time In Vivo Detection of Cellular Senescence through the Controlled Release of the NIR Fluorescent Dye Nile Blue
Authors: Lozano‐Torres Beatriz , Blandez Juan F. , Galiana Irene , García‐Fernández Alba , Alfonso María , Marcos María D. , Orzáez Mar , Sancenón Félix , Martínez‐Máñez Ramón
Published: May 2020

In vivo detection of cellular senescence is accomplished by using mesoporous silica nanoparticles loaded with the NIR‐FDA approved Nile blue (NB) dye and capped with a galactohexasaccharide (S3). NB emission at 672 nm is highly quenched inside S3, yet a remarkable emission enhancement is observed upon cap hydrolysis in the presence of β‐galactosidase and dye release. The efficacy of the probe to detect cellular senescence is tested in vitro in melanoma SK‐Mel‐103 and breast cancer 4T1 cells and in vivo in palbociclib‐treated BALB/cByJ mice bearing breast cancer tumor.
p‐Substituted Tris(2‐pyridylmethyl)amines as Ligands for Highly Active ATRP Catalysts: Facile Synthesis and Characterization
Authors: Enciso Alan E. , Lorandi Francesca , Mehmood Arshad , Fantin Marco , Szczepaniak Grzegorz , Janesko Benjamin G. , Matyjaszewski Krzysztof
Published: May 2020

A facile and efficient two‐step synthesis of p‐substituted tris(2‐pyridylmethyl)amine (TPMA) ligands to form Cu complexes with the highest activity to date in atom transfer radical polymerization (ATRP) is presented. In the divergent synthesis, p‐Cl substituents in tris(4‐chloro‐2‐pyridylmethyl)amine (TPMA3Cl) were replaced in one step and high yield by electron‐donating cyclic amines (pyrrolidine (TPMAPYR), piperidine (TPMAPIP), and morpholine (TPMAMOR)) by nucleophilic aromatic substitution. The [CuII(TPMANR2)Br]+ complexes exhibited larger energy gaps between frontier molecular orbitals and >0.2 V more negative reduction potentials than [CuII(TPMA)Br]+, indicating >3 orders of magnitude higher ATRP activity. [CuI(TPMAPYR)]+ exhibited the highest reported activity for Br‐capped acrylate chain ends in DMF, and moderate activity toward C−F bonds at room temperature. ATRP of n‐butyl acrylate using only 10–25 part per million loadings of [CuII(TPMANR2)Br]+ exhibited excellent control.
Potassium Poly(Heptazine Imide): Transition Metal‐Free Solid‐State Triplet Sensitizer in Cascade Energy Transfer and [3+2]‐cycloadditions
Authors: Savateev Aleksandr , Tarakina Nadezda V. , Strauss Volker , Hussain Tanveer , ten Brummelhuis Katharina , Sánchez Vadillo José Manuel , Markushyna Yevheniia , Mazzanti Stefano , Tyutyunnik Alexander P. , Walczak Ralf , Oschatz Martin , Guldi Dirk M. , Karton Amir , Antonietti Markus
Published: May 2020

Polymeric carbon nitride materials have been used in numerous light‐to‐energy conversion applications ranging from photocatalysis to optoelectronics. For a new application and modelling, we first refined the crystal structure of potassium poly(heptazine imide) (K‐PHI)—a benchmark carbon nitride material in photocatalysis—by means of X‐ray powder diffraction and transmission electron microscopy. Using the crystal structure of K‐PHI, periodic DFT calculations were performed to calculate the density‐of‐states (DOS) and localize intra band states (IBS). IBS were found to be responsible for the enhanced K‐PHI absorption in the near IR region, to serve as electron traps, and to be useful in energy transfer reactions. Once excited with visible light, carbon nitrides, in addition to the direct recombination, can also undergo singlet–triplet intersystem crossing. We utilized the K‐PHI centered triplet excited states to trigger a cascade of energy transfer reactions and, in turn, to sensitize, for example, singlet oxygen (1O2) as a starting point to synthesis up to 25 different N‐rich heterocycles.
Photocatalytic Fluoro Sulfoximidations of Styrenes
Authors: Wang Chenyang , Tu Yongliang , Ma Ding , Bolm Carsten
Published: May 2020

Reactions of difluoroiodotoluene with NH‐sulfoximines provide new hypervalent iodine(III) reagents, which photocatalytically transfer a fluoro and a sulfoximidoyl group onto styrenes with high regioselectivity. The substrate scope is broad with respect to both sulfoximines and olefins. Following an operationally simple protocol, a large library of fluorine‐containing N‐functionalized sulfoximines can be accessed. Results from mechanistic investigations revealed the importance of radical intermediates.
Pillar[n]MaxQ: A New High Affinity Host Family for Sequestration in Water
Authors: Xue Weijian , Zavalij Peter Y. , Isaacs Lyle
Published: May 2020

We report the synthesis, X‐ray crystal structure, and molecular recognition properties of pillar[n]arene derivative P[6]AS, which we refer to as Pillar[6]MaxQ along with analogues P[5]AS and P[7]AS toward guests 1–18. The ultratight binding affinity of P[5]AS and P[6]AS toward quaternary (di)ammonium ions renders them prime candidates for in vitro and in vivo non‐covalent bioconjugation, for imaging and delivery applications, and as in vivo sequestration agents.
The novel composite material MOF‐[Mg3(BTC)2]/GO/Fe3O4 and its use in slow‐release ibuprofen
Authors: Lestari Witri Wahyu , Tedra Rizqi Akbar , Rosari Venansia Avelia , Saraswati Teguh Endah
Published: May 2020

This study aimed to synthesize a composite material consisting of metal–organic framework based magnesium(II) and benzene‐1,3,5‐tricarboxylic acid (H3BTC) and its modification using graphene oxide (GO) and Fe3O4. The obtained material (i.e., [Mg3(BTC)2]/GO/Fe3O4) was studied as a matrix for the slow release of ibuprofen. [Mg3(BTC)2]/GO/Fe3O4 matrices were synthesized ex situ with the sonochemical method (material 1) and in situ with the solvothermal method (material 2). The obtained materials were completely characterized by X‐ray diffraction and Fourier‐transform infrared spectroscopy. Based on scanning electron microscopy imaging, the produced materials were spherical. The presence of GO and Fe3O4 in material 1 and material 2 reduced the surface area, but it increased the adsorption capacity of ibuprofen up to 94.12%. The magnetic properties of materials 1 and 2 were observed using a vibrating sample magnetometer. These results demonstrate that modification of Fe3O4 nanoparticles induces paramagnetic properties in both materials. The presence of this matrix material was able to release ibuprofen up to seven times slower at pH 5.0 and 12 times slower at pH 7.4. An increase in the pH lead to an increase in the concentration of ibuprofen released to 33.31% more than at pH 5.0.
Porous triazine polymer: A novel catalyst for the three‐component reaction
Authors: Nouruzi Nasrin , Dinari Mohammad , Mokhtari Nazanin , Gholipour Behnam , Rostamnia Sadegh , Khaksar Samad , Boluki Rana
Published: May 2020

A new porous triazine‐based covalent organic polymer (Triazine‐COP) was prepared through the Schiff‐base condensation of 2,4,6‐tris(4‐formyl phenoxy)‐1,3,5‐triazine and 4,4′‐oxydianiline, under sonication. The synthesized Triazine‐COP with a high surface area was stable in water and other organic solvents. In the next step, Au (III) ions were immobilized on the nitrogen‐rich Triazine‐COP that on the reduction with NaBH4 produced the heterogeneous catalyst of gold clusters in nanosize (Au‐NCs@Triazine‐COPs). It was applied as an efficient catalyst for the A3 coupling reaction of alkynes, aldehydes with and amines. Both electron‐withdrawing/releasing groups produced the corresponding propargylamines with high yields. The high activity of the Au‐NCs@Triazine‐COPs in this reaction was because of the nanoporous structure of the support that enables the high dispersion and an unhindered open environment for the NCs. The catalyst was reused up to 7 times without significant loss in activity.
Synthesis, structural identification, DNA interaction and biological studies of divalent Mn, Co and Ni chelates of 3‐amino‐5‐mercapto‐1,2,4‐triazole azo ligand
Authors: Gaber Mohamed , El‐Ghamry Hoda A. , Fathalla Shaimaa K.
Published: May 2020

New Mn (II), Co (II) and Ni (II) azo chelates of 3‐amino‐5‐mercapto‐1,2,4‐triazole have been designed and obtained. The structures of these newly isolated complexes were assigned according to elemental, thermal analyses, spectral measurements, conductivity and magnetic moment. The metal complexes were predicted to be not electrolytic from the measured molar conductance values. The magnetic moment and UV–Vis spectral data denoted the formation of octahedral geometries for Mn (II), Co (II) and Ni (II) complexes. Thermal properties and decomposition kinetics of the metal chelates are investigated using Coats‐Redfern method. The kinetic parameters like activation energy (E*), pre‐exponential factor (A) and entropy of activation (ΔS*) were quantified. The geometry of the metal complexes is optimized with the help of molecular modeling. The interaction of metal chelates with calf thymus DNA (CT‐DNA) was evaluatedviaUV–Vis absorption and viscosity measurements. The obtained data elucidated that the Ni (II) chelate interact with DNA by groove binding while partial intercalative binding mode have been predicted for Mn (II) and Co (II) chelates. The estimated binding constants for the DNA‐complexes are 3.85 ± 0.03 × 104, 1.03 ± 0.2 × 105and 2.81 ± 0.02 × 105M−1, for Mn (II), Co (II) and Ni (II) azo chelates, successively. Also, the synthesized complexes were tested for their in‐vitro antimicrobial and anticancer efficacy.
Nanometer‐sized, rod‐like, ligand‐containing tryptophan complexes: Anion influence–structural geometry–antitumor activity correlations
Authors: El‐Husseiny Amel F. , Hassan Hammed H.A.M. , Fadhil Firas M. , Khalil Tarek E.
Published: May 2020

Matrix metalloproteinases (MMPs) are metal‐dependent endopeptidases that are related to the initiation and progression of diseases and are involved in physiological processes such as angiogenesis, wound healing, and embryonic development. Synthetic inhibitors of MMPs are amino acid–based ligands as analyzed by the interactions between the enzyme and its natural substrate. Low production cost and low environmental toxicity of α‐amino acid complexes resulted in a wide pharmacological spectrum, including the anti‐inflammatory and anticonvulsant properties in addition to cytotoxic activities. These facts directed our search for the development of selective inhibitors that contain chemical entity. l‐Tryptophan is a main component of proteins and is essential in human nutrition for establishing and sustaining positive nitrogen balance. Nanomaterials exhibited clinical influence in terms of delivery approaches on bioactive molecules as therapeutic and imaging contrast agents. In this article, we report the synthesis of nanometer rod‐like 2,2′‐(1,3,5,7‐tetraoxopyrrolo[3,4‐f]isoindole‐2,6(1H,3H,5H,7H)‐diyl)bis(3‐(1H‐indol‐3‐yl)propanoic acid) and its metal complexes. The effect of different anions on the geometrical structures and properties of several complexes was studied. Studies indicated that most complexes exhibited dinuclear octahedral or tetrahedral topologies with M–M interaction being absent, whereas mononuclear square planar or square pyramidal topologies were obtained for copper complexes containing chloride or nitrate anions. The ligand exhibited its activity solely against Bacillus subtilis. [Co2(L)Cl2(H2O)2] complex exhibited potent activity against various species of pathogenic microorganisms. The cytotoxicity against MCF‐7 cell line demonstrated that the inhibitory effect is dose dependent. [Cu(HL)Cl.H2O] complex exhibited an interesting cytotoxic activity in addition to copper anticancer analogues, the alternatives to cis‐platin because of their biocompatibility and important roles in biological systems.
Enhanced electronic and nonlinear optical responses of C24N24cavernous nitride fullerene by decoration with first row transition metals; A computational investigation
Authors: Shakerzadeh Ehsan , Mashak Shabavi Zahra , Anota Erneto Chigo
Published: May 2020

The electronic (energy gap and work function) as well as electrical properties (dipole moment, polarizability, and first hyperpolarizabilities) of the first‐row transition metals decorated C24N24cavernous nitride fullerene were explored using DFT calculations. The transition metals are decorated at N4 cavity of C24N24fullerene. According to our spin polarized computations, the most stable spin state monotonically increases to sextet for Mn@C24N24and thereafter dropped off gradually to singlet state for Zn@C24N24system. The findings demonstrate that transition metals can remarkably decrease the HOMO‐LUMO energy gap and work function values up to 63% and 21% of bare C24N24, respectively. As can be seen, when the Sc and Ti metals are located above the N4 cavity of fullerene, systems of enhanced static hyperpolarizabilities (β0) are delivered. These findings might provide an effective strategy to design high performance eletcro‐optical materials based on carbon‐ nitride fullerene.
Ligational, DFT modeling and biological properties of some new metal complexes with 3‐(bromoacetyl)coumarin and 1,10‐phenanthroline
Authors: El‐Shwiniy Walaa H. , Gamil Manar A. , Sadeek Sadeek A. , Zordok Wael A. , El‐farargy Ahmed F.
Published: May 2020

The synthesis and characterization of Mn (II), Fe (II), Co (II), Ni (II), Cu (II) and Zn (II) complexes with 3‐(bromoacetyl)coumarin (BAC) in presence of 1,10‐phenanthroline (Phen) were reported and described by elemental analysis, molar conductivity, FT‐IR, UV–Vis and effective magnetic moments. TG and DTG have been applied to study the decomposition mechanisms for BAC, Phen and their complexes. The analytical results and spectral studies showed that BAC and Phen act as bidentate ligands via oxygen of α, β‐unsaturated ketone and oxygen of lactone carbonyl of coumarin and two pyridyl nitrogen atoms of Phen. Octahedral geometries have been proposed for all complexes and the kinetic parameter (E*, ΔH*, ΔS* and ΔG*) were calculated using Coats‐Redfern (CR) and Horowitz‐Metzeger (HM) methods. DFT calculations (bond lengths, bond angles, total energy, heat of formation, dipole moment and the lowest energy model structures) have been determined. The antibacterial activities for synthesized complexes were assayed against some selected bacterial and the complexes displayed a very highly significant against L. monocytogens.
Platinum‐Imidazolyl Schiff Base Complexes Immobilized in Periodic Mesoporous Organosilica Frameworks as Catalysts for Hydrosilylation
Authors: Huo Yingpeng , Hu Jiwen , Tu Yuanyuan , Huang Zhenzhu , Lin Shudong , Hu Yangfei , Feng Chao
Published: May 2020

An imidazolyl Schiff base‐containing periodic mesoporous organosilica (PMO) was synthesized via co‐condensation reactions between a newly prepared bis (imidazolyl)imine‐bridged bis silane and tetraethyl orthosilicate in the presence of cetyltrimethyl ammonium bromide as a soft template. The resultant as‐synthesized PMO was then employed as a solid support for platinum catalysts. This complex was fully characterized via various techniques including FTIR, solid‐state13C NMR, and 29Si‐NMR spectroscopy, as well as N2 adsorption/desorption analysis, X‐ray diffraction (XRD), X‐ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) methods. In addition, the catalyst was proven to efficiently mediate hydrosilylation reactions between olefins and hydrosilanes, and it can be reused for at least five cycles without significant loss of activity.
Green synthesis, characterization, and biological activities of saffron leaf extract‐mediated zinc oxide nanoparticles: A sustainable approach to reuse an agricultural waste
Authors: Rahaiee Somayeh , Ranjbar Mojtaba , Azizi Hossein , Govahi Mostafa , Zare Mahboobeh
Published: May 2020

To increase the profitability and sustainability of agricultural waste, a facile green approach was established to synthesize zinc oxide nanoparticles (ZnO NPs) using saffron leaf extract as a reducing and stabilizing agent. Structural characteristics of NPs were investigated by X‐ray diffraction (XRD), Fourier‐transform infrared (FTIR), field emission scanning electron microscopy (FESEM), and UV–Visible (UV–Vis) spectroscopy. Characterization results revealed that ZnO NPs is highly crystalline with a hexagonal wurtzite structure and spherical particles with diameter less than 50 nm, as confirmed by XRD and FESEM techniques. UV–Vis absorption spectra depicted an absorption peak at 370 nm, which confirms the formation of ZnO NPs. FTIR spectral analysis confirmed the presence of functional groups and metal oxygen groups. The biological activities of ZnO NPs were also investigated. The antibacterial effect of ZnO NPs was investigated against selected food pathogens (Salmonella Typhimurium, Listeria monocytogenes, and Enterococcus faecalis). The study results prove that the green synthesized ZnO NPs show enhanced antibacterial activity against S. Typhimurium when compared with other strains. A dose‐dependent free radical scavenging activity was observed for ZnO NPs in both 2,2‐diphenyl‐1‐picryl‐hydrazyl‐hydrate (DPPH) and fluorescence recovery after photobleaching (FRAP) assays. The ZnO NPs were evaluated for their photocatalytic activity during the degradation of methylene blue (MB) dye in aqueous solutions. The maximum removal of MB achieved was 64% with an initial ZnO NP concentration of 12 mg/mL under UV light. The present study revealed that the agricultural waste (saffron leaf) provides a simple and eco‐friendly option to sustainably synthesize ZnO NPs for use as a photocatalyst. In addition, this is the first report on saffron leaf‐mediated synthesis of ZnO NPs.
Blue Highly Fluorescent Boranil Derived From Anil Ligand: Synthesis, Characterization, Experimental and Theoretical Evaluation of Solvent Effect on Structures and Photophysical Properties
Authors: Agren Soumaya , Chaabene Marwa , Allouche Abdul‐Rahman , Ben Chaâbane Rafik , Lahcinie Mohamed , Baouab Mohamed Hassen V
Published: May 2020

In this study, we report the design and the synthesis of a Schiff base; Anil and its corresponding Boron Difluoride complexe; Boranil. The synthesis procedure was carried out adopting new, optimized reaction conditions. The Boranil dye presents the advantage to be emissive in solution. 1H and 19F NMR along with FTIR confirmed both compound's structure. To gain a better understanding of the solvatochromic behavior of Anil and Boranil, the dependence of the absorption spectra on the solvent's polarity was studied in depth. Thus, UV–Vis spectroscopy was performed in five selected solvents. In addition to the solvent's polarity effect, the influence of BF2 moiety introduction on the molecule's photophysical properties was also evaluated. When examining different absorption spectra, we found that the title fluorescent dye exhibited weak solvatochromic (11 nm in THF) as well as a slight redshift broader and relatively more structured absorption spectra after complexation. Besides, we investigate the obtained key structure–property relationships through DFT and TD‐DFT calculations using a 6–311++ G (d, p) basis set. Quantum chemical calculations allowed confirming proposed structures and understanding their electronic structure in larger details. Theoretical results also showed good agreement with the experimental findings. Finally, the frontier molecular orbitals were investigated to illustrate the pi‐conjugation and charge transfer effect.
Impact of ultrasonication on carbon nanotube demixing and damage in polymer nanocomposites
Authors: Iyer Ganapathi Jayadurga , Lee Stephanie S. , Kalyon Dilhan M. , Fisher Frank T.
Published: May 2020

While ultrasonication is universally employed for dispersion and distribution of carbon nanotubes (CNTs) in a solvent or polymer solution, the current work focuses on the underlying mechanisms of CNT demixing and CNT damage that can occur during processing. Here, multi‐walled CNTs were dispersed in a polycaprolactone polymer matrix using an established solution processing technique. Electrical, rheological, and mechanical characterization results suggest that once nanocomposite property enhancements reach an optimal level, further sonication leads to a decrease in the corresponding properties due to a combination of CNT damage and demixing mechanisms. Evidence of CNT damage from transmission electron microscopy, poor CNT distribution from optical image analysis and shear‐induced crystallization results, and reagglomeration observed from ultraviolet–visible results, taken together, suggest that mechanisms of demixing and damage of the CNTs coexist for excessive sonication times.
Effect of TPU hard segment content on the rheological and mechanical properties of PLA/TPU blends
Authors: Nofar Mohammadreza , Mohammadi Mojtaba , Carreau Pierre J.
Published: May 2020

Blends of an amorphous polylactide (PLA) with three different thermoplastic polyurethane (TPU) grades having various hard segment (HS) contents are prepared at the blending ratio of 85/15 wt% through a twin‐screw extruder (TSE) at processing temperatures of 150 and 190°C. Blends of a semicrystalline PLA with 15 wt% of the noted TPU grades are also processed in the TSE at 190°C to investigate the matrix crystallization effect on the morphology and property enhancements. The rheological experiments reveal that the increase in TPU HS content significantly increases the phase compatibility between PLA and TPU as also suggested by the finer morphology of the TPU phase, although the use of lower HS TPUs is more favorable to enhance the ductility and impact properties of the blends.