bluuebunny/crossref_metadata_2025_split huggingface dataset:
Variable selection in support vector regression using angular search algorithm and variance inflation factor
Authors: Folli Gabriely S. , Nascimento Márcia H.C. , de Paulo Ellisson H. , da Cunha Pedro H.P. , Romão Wanderson , Filgueiras Paulo R. 
Published: July 2020

AbstractHere, we combine angular search algorithm and variance inflation factor (ASA‐VIF) with support vector regression (SVR) (ASA‐VIF‐SVR) to estimate total acid number (TAN), basic nitrogen content (BNC), and sulfur content (SC) in Brazilian crude oils. To prevent the interference of outliers, we further developed a strategy for outlier identification and applied it to nonlinear models based on RMSE (root mean square error). ASA‐VIF‐SVR was applied to near‐ and mid‐infrared spectroscopy (NIR and MIR) and hydrogen nuclear magnetic resonance (1H NMR) spectroscopy data available in a range of 93–194 samples. The models were evaluated for accuracy (root mean square error of calibration [RMSEC] and root mean square error of prediction [RMSEP]) and linearity (coefficient of determination, R2). The removal of outliers increased accuracy and linearity of our models. The ASA‐VIF model for TAN, BNC, and SC selected 0.37%, 0.93%, and 0.30% of variables from full NIR spectra; 0.21%, 0.27%, and 0.21% from full MIR; and 0.20%, 0.42%, and 0.15% from full 1H NMR. In most cases, the best results were obtained with variable selection compared with the full dataset. Also, 1H NMR generated more accurate and linear models with RMSEP and R2p of 0.0071 wt% and 0.86 for BNC and 0.0623 wt% and 0.79 for SC. TAN showed a better MIR result with RMSEP of 0.1426 mg KOH g–1 and R2p of 0.47. The most important region for 1H NMR and MIR was the one with the largest quantity of unpaired electrons (aromatic region).
Asymmetric Host Molecule Bearing Pyridine Core for Highly Efficient Blue Thermally Activated Delayed Fluorescence OLEDs
Authors: Yoon Jiwon , Kim Seong Keun , Kim Hyung Jong , Choi Suna , Jung Sang Won , Lee Hyuna , Kim Jun Yun , Yoon Dae‐Wi , Han Chang Wook , Chae Weon‐Sik , Kwon Jang Hyuk , Cho Min Ju , Choi Dong Hoon 
Published: July 2020

AbstractIn this study, two host materials, pCzBzbCz and pCzPybCz, are synthesized to achieve a high efficiency and long lifetime of blue thermally activated delayed fluorescence organic light‐emitting diodes (TADF‐OLEDs). The molecular design strategy involves the introduction of a pyridine group into the core structure of pCzPybCz as an electron‐withdrawing unit, and an electron‐donating phenyl group into the structure of pCzBzbCz. These host materials demonstrate good thermal stability and high triplet energy (T1=3.07 eV for pCzBzbCz and 3.06 eV for pCzPybCz) for the fabrication of blue TADF‐OLEDs. In particular, pCzPybCz‐based OLED devices demonstrate an external quantum efficiency (EQE) of 22.7 % and an operational lifetime of 24 h (LT90, time to attain 90 % of initial luminance) at an initial luminance of 1000 cd m−2. This superior lifetime could be explained by the C−N bond dissociation energy (BDE) in the host molecular structure. Furthermore, a mixed‐host system using the electron‐deficient 2,4‐bis(dibenzo[b,d]furan‐2‐yl)‐6‐phenyl‐1,3,5‐triazine (DDBFT) is proposed to inhibit the formation of the anion state of our host materials. In short, the device operational lifetime is further improved by applying DDBFT. The carbazole‐based asymmetric host molecule containing a pyridine core realizes a high‐efficiency blue TADF‐OLED showing a positive effect on the operating lifetime, and can provide useful strategies for designing new host materials.
Excitation Energy Transfer and Exchange‐Mediated Quartet State Formation in Porphyrin‐Trityl Systems
Authors: Nolden Oliver , Fleck Nico , Lorenzo Emmaline R. , Wasielewski Michael R. , Schiemann Olav , Gilch Peter , Richert Sabine 
Published: July 2020

AbstractPhotogenerated multi‐spin systems hold great promise for a range of technological applications in various fields, including molecular spintronics and artificial photosynthesis. However, the further development of these applications, via targeted design of materials with specific magnetic properties, currently still suffers from a lack of understanding of the factors influencing the underlying excited state dynamics and mechanisms on a molecular level. In particular, systematic studies, making use of different techniques to obtain complementary information, are largely missing. This work investigates the photophysics and magnetic properties of a series of three covalently‐linked porphyrin‐trityl compounds, bridged by a phenyl spacer. By combining the results from femtosecond transient absorption and electron paramagnetic resonance spectroscopies, we determine the efficiencies of the competing excited state reaction pathways and characterise the magnetic properties of the individual spin states, formed by the interaction between the chromophore triplet and the stable radical. The differences observed for the three investigated compounds are rationalised in the context of available theoretical models and the implications of the results of this study for the design of a molecular system with an improved intersystem crossing efficiency are discussed.
Photocatalytic Reductive Radical‐Polar Crossover for a Base‐Free Corey–Seebach Reaction
Authors: Donabauer Karsten , Murugesan Kathiravan , Rozman Urša , Crespi Stefano , König Burkhard 
Published: July 2020

AbstractA metal‐free generation of carbanion nucleophiles is of prime importance in organic synthesis. Herein we report a photocatalytic approach to the Corey–Seebach reaction. The presented method operates under mild redox‐neutral and base‐free conditions giving the desired product with high functional group tolerance. The reaction is enabled by the combination of photo‐ and hydrogen atom transfer (HAT) catalysis. This catalytic merger allows a C−H to carbanion activation by the abstraction of a hydrogen atom followed by radical reduction. The generated nucleophilic intermediate is then capable of adding to carbonyl electrophiles. The obtained dithiane can be easily converted to the valuable α‐hydroxy carbonyl in a subsequent step. The proposed reaction mechanism is supported by emission quenching, radical–radical homocoupling and deuterium labeling studies as well as by calculated redox‐potentials and bond strengths.
P450 CYP17A1 Variant with a Disordered Proton Shuttle Assembly Retains Peroxo‐Mediated Lyase Efficiency
Authors: Liu Yilin , Denisov Ilia G. , Grinkova Yelena V. , Sligar Stephen G. , Kincaid James R. 
Published: July 2020

AbstractHuman cytochrome P450 CYP17A1 first catalyzes hydroxylation at the C17 position of either pregnenolone (PREG) or progesterone (PROG), and a subsequent C17−C20 bond scission to produce dehydroepiandrosterone (DHEA) or androstenedione (AD). In the T306A mutant, replacement of the Threonine 306 alcohol functionality, essential for efficient proton delivery in the hydroxylase reaction, has only a small effect on the lyase activity. In this work, resonance Raman spectroscopy is employed to provide crucial structural insight, confirming that this mutant, with its disordered proton shuttle, fails to generate essential hydroxylase pathway intermediates, accounting for the loss in hydroxylase efficiency. Significantly, a corresponding spectroscopic study with the susceptible lyase substrate, 17‐OH PREG, not only reveals an initially trapped peroxo‐iron intermediate experiencing an H‐bond interaction of the 17‐OH group with the proximal oxygen of the Fe‐Op‐Ot fragment, facilitating peroxo‐ attack on the C20 carbon, but also unequivocally shows the presence of the subsequent hemiketal intermediate of the lyase reaction.
S‐Trifluoroethyl Benzenesulfonothioate: A Bench‐Stable Reagent for Electrophilic Trifluoroethylthiolation†
Authors: Huang Shuai , Xia Ziheng , Lu Kui , Lu Haifeng , Tung Chen‐Ho , Xu Zhenghu 
Published: July 2020

Summary of main observation and conclusionWe report herein a practical approach for synthesis of an electrophilic trifluoroethylthiolation reagent PhSO2SCH2CF3 (1) from easily available materials. The reaction proceeded through a protonation and nucleophilic substitution cascade of the in situ formed trifluorodiazoethane. This bench‐stable reagent could easily be applied to introduce trifluoroethylthio group into small organic molecules.
The Origins of Toroidal Micelles from a Liquid–Crystalline Triblock Copolymer†
Authors: Jin Bixin , Liu Guojun , Li Xiaoyu 
Published: July 2020

Summary of main observation and conclusionIn this paper, we reported a systematic study on the formation mechanism of bent toroidal micelles from a triblock copolymer poly(acrylic acid)‐block‐(2‐cinnamoyloxylethyl methacrylate)‐block‐poly(perfluorooctylethyl methacrylate) (PAA‐b‐PCEMA‐b‐ PFMA) in the binary solvent mixture of methanol and α,α,α‐trifluorotoluene (MeOH/TFT) through a heating‐cooling procedure. It was found that the formation process of toroids was predominantly kinetic‐controlled, and can be influenced by the preparation protocol, solvent composition and stirring rate of the solutions. The toroids were formed via a complicated morphological transition process. At high temperature, the polymer formed bilayered vesicles with bumpy surface, while upon cooling, the vesicles broke and unfolded into bumpy platelet micelles, which subsequently perforated into toroidal and cylindrical micelles upon further cooling. Besides the distinct and unique bumpy vesicle and platelet structures, the transformation mechanisms from vesicular to platelet, and toroidal micelles are also very intriguing, and may provide new insights into the interconversion of micellar morphologies.
Identification of a Suitable Peptidic Molecular Platform for the Development of NPY(Y1)R‐Specific Imaging Agents
Authors: Krieger Korbinian , Wängler Björn , Schirrmacher Ralf , Wängler Carmen 
Published: July 2020

AbstractNPY(Y1)R (neuropeptide Y receptor subtype 1) is an important target structure for tumor‐specific imaging and therapy as this receptor subtype is overexpressed in very high density and incidence especially in human breast cancer. Targeting this receptor with radiolabeled truncated analogues of the endogenous ligand NPY (neuropeptide Y) has, however, not yet resulted in satisfactory imaging results when using positron emission tomography (PET). This can be attributed to the limited stability of these PET imaging agents caused by their fast proteolytic degradation. Although highly promising NPY analogues were developed, their stability has only been investigated in very few cases. In this systematical work, we comparatively determined the stability of the five most promising truncated analogues of NPY that were developed over the last years, showing the highest receptor affinities and subtype selectivities. The stability of the peptides was assessed in human serum as well as in a human liver microsomal stability assay; these gave complementary results, thus demonstrating the necessity to perform both assays and not just conventional serum stability testing. Of the tested peptides, only [Lys(lauroyl)27,Pro30,Lys(DOTA)31,Bip32,Leu34]NPY27‐36 showed high stability against peptidase degradation; thus this is the best‐suited truncated NPY analogue for the development of NPY(Y1)R‐specific imaging agents.
Ligand‐Free Yolk‐Shell Nanoparticles: Synthesis and Catalytic Applications
Authors: Shaik Firdoz 
Published: July 2020

AbstractLigand‐Free yolk‐shell nanoparticles (LFYSNs) consist of ligand‐free core (nanoparticle) enclosed in a hollow nanocavity of a porous shell have been attracted great interest owing to their unique nanoarchitecture features, enchanting physicochemical properties and extensive potential applications. LFYSNs are considered as a unique category of conventional yolk‐shell nanoparticles (YSNs). YSNs are usually consist of organic‐capped core (nanoparticle) and the presence of capping ligands on the surface of metal core may show deleterious effects in catalytic applications. Here, a comprehensive overview on the recent progress of LFYSNs synthetic strategies and catalytic applications are discussed. The fabrication methods for LFYSNs are mainly focused on a ‘‘ship‐in‐a‐bottle/pre‐shell’’ approach and sub‐divided into three categories, including volume confined, photochemical and seedless/colloidal methods. The catalytic applications of LFYSNs including chemical and photo catalysis, and electrocatalysis are discussed in detail. Moreover, the superlative catalytic activity of LFYSNs is highlighted. Finally, perspectives on future research direction and development of LFYSNs are discussed briefly.
Model‐Informed Drug Development of the Masked Anti‑PD‑L1 Antibody CX‐072
Authors: Stroh Mark , Green Michelle , Millard Bjorn L. , Apgar Joshua F. , Burke John M. , Garner Will , Lu Hong , Lyman Susan K. , Desnoyers Luc R. , Richardson Jennifer , Hannah Alison , Kavanaugh W. Michael 
Published: July 2020

CX‑072 is an anti‑PD‑L1 (programmed death ligand 1) Probody therapeutic (Pb‐Tx) designed to be preferentially activated by proteases in the tumor microenvironment and not in healthy tissue. Here, we report the model‐informed drug development of CX‐072. A quantitative systems pharmacology (QSP) model that captured known mechanisms of Pb‐Tx activation, biodistribution, elimination, and target engagement was used to inform clinical translation. The QSP model predicted that a trough level of masked CX‐072 (intact CX‐072) of 13–99 nM would correspond to a targeted, 95% receptor occupancy in the tumor. The QSP model predictions appeared consistent with preliminary human single‑dose pharmacokinetic (PK) data following CX‐072 0.03–30.0 mg/kg as monotherapy: CX‑072 circulated predominantly as intact CX‐072 with minimal evidence of target‐mediated drug disposition. A preliminary population PK (POPPK) analysis based upon 130 subjects receiving 0.03–30.0 mg/kg as monotherapy included a provision for a putative time‐dependent and dose‐dependent antidrug antibody (ADA) effect on clearance (CL) with a mixture model. Preliminary POPPK estimates for intact CX‐072 time‐invariant CL and volume of distribution were 0.306 L/day and 4.84 L, respectively. Exposure–response analyses did not identify statistically significant relationships with best change from baseline sum of measurements and either adverse events of grade ≥ 3 or of special interest. Simulations suggested that > 95% of patients receiving CX‐072 10 mg/kg every two weeks would exceed the targeted trough level regardless of ADA, and that dose adjustment by body weight was not necessary, supporting a fixed 800 mg dose for evaluation in phase II.
Exposure–Response Analyses of Anaplastic Lymphoma Kinase Inhibitors Crizotinib and Alectinib in Non‐Small Cell Lung Cancer Patients
Authors: Groenland Stefanie L. , Geel Dieuwertje R. , Janssen Julie M. , de Vries Niels , Rosing Hilde , Beijnen Jos H. , Burgers Jacobus A. , Smit Egbert F. , Huitema Alwin D.R. , Steeghs Neeltje 
Published: July 2020

Crizotinib and alectinib are anaplastic lymphoma kinase (ALK)‐inhibitors indicated for the treatment of ALK‐positive metastatic non‐small cell lung cancer (NSCLC). At the currently used fixed doses, interindividual variability in exposure is high. The aim of this study was to investigate whether minimum plasma concentrations (Cmin) of crizotinib and alectinib are related to efficacy and toxicity. An observational study was performed, in which ALK‐positive NSCLC patients who were treated with crizotinib and alectinib and from whom pharmacokinetic samples were collected in routine care, were included in the study. Exposure–response analyses were explored using previously proposed Cmin thresholds of 235 ng/mL for crizotinib and 435 ng/mL for alectinib. Forty‐eight crizotinib and 52 alectinib patients were included. For crizotinib, median progression‐free survival (mPFS) was 5.7 vs. 17.4 months for patients with Cmin < 235 ng/mL (48%) and ≥ 235 ng/mL, respectively (P = 0.08). In multivariable analysis, Cmin < 235 ng/mL resulted in a hazard ratio (HR) of 1.79 (95% confidence interval (CI), 0.90–3.59, P = 0.100). In a pooled analysis of all crizotinib patients (not only ALK‐positive, n = 79), the HR was 2.15 (95% CI, 1.21–3.84, P = 0.009). For alectinib, mPFS was 12.6 months vs. not estimable (95% CI, 19.8–not estimable) for patients with Cmin < 435 ng/mL (37%) and ≥ 435 ng/mL, respectively (P = 0.04). Multivariable analysis resulted in an HR of 4.29 (95% CI, 1.33–13.90, P = 0.015). In conclusion, PFS of crizotinib and alectinib treated NSCLC patients is prolonged in patients with Cmin ≥ 235 ng/mL and 435 ng/mL, respectively. Therefore, therapeutic drug monitoring should be part of routine clinical management for these agents.
The moderating role of personal value orientation on the links between perceived corporate social performance and purchase intentions
Authors: Alniacik Esra , Moumen Charefeddine , Alniacik Umit 
Published: July 2020

AbstractThis study examines how personal values affect the impact of perceived CSR aspects on purchase intentions by investigating the differences between two groups of customers, which are customers with more self‐centered values (self‐enhancement value orientation) and customers with more altruistic values (self‐transcendent value orientation). The research sample consisted of 356 customers of six banks in Algiers, capital city of Algeria. Research hypotheses were tested by structural equation modeling (SEM). Data analyses revealed that personal values can change the strength and the direction of the relationship between the perceived economic and philanthropic aspects of CSR on purchase intentions. However, no such effect is detected on the links between perceived legal and ethical aspect of CSR and purchase intentions. Customers with self‐enhancement values are more interested in economic and legal aspects of CSR, whereas customers with self‐transcendence values are mainly interested in philanthropic aspect of CSR. Research and managerial implications of the findings are discussed.
Volatile molecules for COVID‐19: A possible pharmacological strategy?
Authors: Colalto Cristiano 
Published: July 2020

AbstractCOVID‐19 is a novel coronavirus disease with a higher incidence of bilateral pneumonia and pleural effusion. The high pulmonary tropism and contagiousness of the virus, severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2), have stimulated new approaches to combat its widespread diffusion. In developing new pharmacological strategies, the chemical characteristic of volatility can add therapeutic value to the hypothetical drug candidate. Volatile molecules are characterized by a high vapor pressure and are consequently easily exhaled by the lungs after ingestion. This feature could be exploited from a pharmacological point of view, reaching the site of action in an uncommon way but allowing for drug delivery. In this way, a hypothetical molecule for COVID‐19 should have a balance between its lung exhalation characteristics and both antiviral and anti‐inflammatory pharmacological action. Here, the feasibility, advantages, and disadvantages of a therapy based on oral administration of possible volatile drugs for COVID‐19 will be discussed. Both aerosolized antiviral therapy and oral intake of volatile molecules are briefly reviewed, and an evaluation of 1,8‐cineole is provided in view of a possible clinical use and also for asymptomatic COVID‐19.
Room without a view—Den excavation in relation to body size in brown bears
Authors: Shiratsuru Shotaro , Friebe Andrea , Swenson Jon E. , Zedrosser Andreas 
Published: July 2020

AbstractHibernation is an adaptive strategy to survive harsh winter conditions and food shortage. The use of well‐insulated winter dens helps animals minimize energy loss during hibernation. Brown bears (Ursus arctos) commonly use excavated dens for hibernation. Physical attributes of excavated dens are expected to impact the bear's heat retention and energy conservation. The objective of this study was to examine the determinants of cavity size of excavated dens and the impact of physical attributes of excavated dens on energy conservation in hibernating bears, hypothesizing that bears excavate dens in a way to minimize heat loss and optimize energy conservation during hibernation. We predicted that den cavity size would be determined by the bear's body size and that older bears would excavate better‐fitting cavities to minimize heat loss, due to their previous experience. We further predicted that physical attributes of excavated dens would affect the bears’ posthibernation body condition. Our results revealed that bears excavated a den cavity in relation to their body size, regardless of sex, and that older bears tended to excavate better‐fitting den cavities compared to young bears, as we expected. Older bears excavated better‐fitting den cavities, suggesting a potentially experience‐based shift with age in den‐excavation behavior and an optimum cavity size relative to a bear's body size. Our key finding is that insulation of excavated dens provided by wall/rood thickness and bedding materials had a significant positive effect on bears’ posthibernation body condition. We believe that our study provides new insight into how not only the quality of denning habitat, but also the quality of dens may affect hibernating animals, by presenting a potential adaptive aspect of den preparation (age effect on efficiency in den excavation) and effect of den attributes on the posthibernation body condition of brown bears.
Direct effects of nitrogen addition on seed germination of eight semi‐arid grassland species
Authors: Zhang Tong , Liu Mengzhou , Huang Xudong , Hu Wei , Qiao Ning , Song Hongquan , Zhang Bing , Zhang Rui , Yang Zhongling , Liu Yinzhan , Miao Yuan , Han Shijie , Wang Dong 
Published: July 2020

AbstractSeed germination plays an important role in mediating plant species composition of grassland communities under nitrogen (N) enrichment. Shifts of plant community structure with N‐enhanced deposition in terrestrial ecosystems have occurred globally. Despite numerous studies about the effects of enhanced N deposition on mature plant communities, few studies have focused on seed germination. Using a laboratory experiment, we report the effects of five N concentrations, including 0, 5, 10, 20, and 40 mM N (NH4NO3) on seed germination of eight semi‐arid grassland species. Results showed that low N concentrations (5‐ and 20‐mM N) promoted mean final germination proportion of all eight species by 4.4% and 6.4%, but high concentrations (40 mM N) had no effect. The mean germination rate was decreased 2.1% and 5.1% by higher N concentration (20‐ and 40‐mM N) levels, but germination start time showed the opposite trend, delayed by 0.7, 0.9, and 1.8 d for the 10, 20, and 40 mM N treatments. Final germination proportion, mean germination rate, and germination start time were significantly different among species in response to N concentration treatments. The final germination proportion of Allium tenuissimum and Chenopodium glaucum were suppressed by increased N concentration, whereas it increased for Potentilla bifurca, Plantago asiatica, and Setaria viridis. Our findings provide novel insights into N deposition‐induced species loss based on seed germination factors in semi‐arid grassland communities.