bluuebunny/crossref_metadata_2025 huggingface dataset:
Collisional mechanics of the diagonal gaits of horses over a range of speeds
Authors: Hobbs Sarah Jane , Clayton Hilary M.
Published: September 2019

One of the goals of the neuromotor control system is to minimize the cost of locomotion by reducing mechanical energy losses. Collisional mechanics, which studies the redirection of the downwards motion of the center of mass (COM) by ground reaction forces (GRF) generated by the limbs, represents an important source of energy loss. The primary objective of this study was to compare collisional mechanics and the associated mechanical energy losses in horses performing diagonally-synchronized gaits over a range of speeds. It is to be expected that collisional energy losses will be high when the COM velocity vector is closely aligned with the GRF vector. This condition is achieved in piaffe, an artificial gait performed in dressage competitions that has a diagonal limb coordination pattern similar to trot but performed with little or no forward velocity. Therefore, we hypothesized that collisional energy losses would be higher in piaffe than in trot. Synchronized kinematic and GRF data were collected from three highly-trained horses performing piaffe, passage and trot at a range of speeds. Derived variables were vertical excursion and velocity of the trunk COM, fore and hind limb compression expressed as percentage reduction of standing limb lengths, range of limb pro-retraction, GRF vector magnitude and vector angle, collision angle (Φ), and mechanical cost of motion (CoMotmech). Linear regression was used to investigate the relationship between CoMotmechand speed for each gait. Partial correlation was used to seek relationships between COM excursion and limb mechanics for each gait. Piaffe, passage and trot were clearly separated on the basis of speed. In all gaits the trunk was high at contact and lift off and descended to its lowest point in midstance following the pattern typical of spring mass mechanics. Mechanical cost was significantly (p < .05) and inversely related to speed in trot and piaffe with the value increasing steeply as speed approached zero due to a near vertical orientation of both the COM velocity vector and the GRF vector. Limb compression during stance was significantly (p < .05) linked to trunk COM vertical excursion in all gaits, with a stronger relationship in the forelimb. Hindlimb compression was, however, large in piaffe where the force magnitudes are notably smaller. The study illustrates the potential value of studying artificial gaits to provide data encompassing the entire range of locomotor capabilities. The results supported the experimental hypothesis by showing a threefold increase in collisional energy losses in piaffe compared with trot. In all gaits, dissociation between diagonal limb contacts and lift offs was thought to be an important strategy in reducing in collisional losses. Piaffe, the most costly gait, has similar characteristics to hopping on the spot. It appears that greater hindlimb compliance and a lower step frequency are important energy conservation strategies for piaffe.
Characteristics and prognosis of pelvic Ewing sarcoma: a SEER population-based study
Authors: Chen Li , Long Cheng , Liu Jiaxin , Xing Fei , Duan Xin
Published: September 2019

Background

The pelvis is one of the primary sites of Ewing sarcoma (ES) and is associated with poorer prognoses than the extremities. Due to the rarity of this disease and limited data available, the prognostic factors of pelvic ES remain controversial. Thus, this study aimed to identify independent prognostic factors, and develop a nomogram for predicting survival rates in patients with pelvic ES.

Methods

Using data provided by the Surveillance, Epidemiology, and End Results (SEER) database, variables including age, sex, race, tumor size, tumor stage, surgery, and radiotherapy were analyzed using the Kaplan–Meier method and Cox proportional hazards regression. Based on the results of multivariate analyses, a nomogram was built to predict the overall survival (OS) of patients with pelvic ES. The performance of the nomogram was evaluated by the concordance index (C-index).

Results

A total of 267 cases diagnosed between 2004 and 2016 were included in the study. Univariate and multivariate analyses showed that patients who were younger, white, had a localized tumor stage, or underwent surgery were associated with improved prognoses, while no significant differences were observed in OS based on sex, tumor size, or radiotherapy. A nomogram was developed and the C-index was 0.728, indicating adequate performance for survival prediction.

Conclusions

Age, race, tumor stage, and surgery were identified as independent prognostic factors for the OS of pelvic ES. The nomogram developed in this study can individually predict 3- and 5-year OS in patients with pelvic ES.
MYB transcription factors in alfalfa (Medicago sativa): genome-wide identification and expression analysis under abiotic stresses
Authors: Zhou Qiang , Jia Chenglin , Ma Wenxue , Cui Yue , Jin Xiaoyu , Luo Dong , Min Xueyang , Liu Zhipeng
Published: September 2019

Background

Alfalfa is the most widely cultivated forage legume and one of the most economically valuable crops in the world. Its survival and production are often hampered by environmental changes. However, there are few studies on stress-resistance genes in alfalfa because of its incomplete genomic information and rare expression profile data. The MYB proteins are characterized by a highly conserved DNA-binding domain, which is large, functionally diverse, and represented in all eukaryotes. The role of MYB proteins in plant development is essential; they function in diverse biological processes, including stress and defense responses, and seed and floral development. Studies on the MYB gene family have been reported in several species, but they have not been comprehensively analyzed in alfalfa.

Methods

To identify more comprehensive MYB transcription factor family genes, the sequences of 168 Arabidopsis thaliana, 430 Glycine max, 185 Medicago truncatula, and 130 Oryza sativa MYB proteins were downloaded from the Plant Transcription Factor Database. These sequences were used as queries in a BLAST search against the M. sativa proteome sequences provided by the Noble Research Institute.

Results

In the present study, a total of 265 MsMYB proteins were obtained, including 50 R1-MYB, 186 R2R3-MYB, 26 R1R2R3-MYB, and three atypical-MYB proteins. These predicted MsMYB proteins were divided into 12 subgroups by phylogenetic analysis, and gene ontology (GO) analysis indicated that most of the MsMYB genes are involved in various biological processes. The expression profiles and quantitative real-time PCR analysis indicated that some MsMYB genes might play a crucial role in the response to abiotic stresses. Additionally, a total of 170 and 914 predicted protein–protein and protein-DNA interactions were obtained, respectively. The interactions between MsMYB043 and MSAD320162, MsMYB253 and MSAD320162, and MsMYB253 and MSAD308489 were confirmed by a yeast two-hybrid system. This work provides information on the MYB family in alfalfa that was previously lacking and might promote the cultivation of stress-resistant alfalfa.
Urine proteome changes in rats subcutaneously inoculated with approximately ten tumor cells
Authors: Wei Jing , Meng Wenshu , Gao Youhe
Published: September 2019

Background

Biomarkers are changes associated with the disease. Urine is not subject to homeostatic control and therefore accumulates very early changes, making it an ideal biomarker source. Usually, we have performed urinary biomarker studies involving at least thousands of tumor cells. However, no tumor starts from a thousand tumor cells. We therefore examined urine proteome changes in rats subcutaneously inoculated with approximately ten tumor cells.

Methods

Here, we serially diluted Walker-256 carcinosarcoma cells to a concentration of 102/mL and subcutaneously inoculated 0.1 mL of these cells into nine rats. The urine proteomes on days 0, 13 and 21 were analyzed by liquid chromatography coupled with tandem mass spectrometry.

Results

Hierarchical clustering analysis showed that the urine proteome of each sample at three time points were clustered into three clusters, indicating the good consistency of these nine rats when inoculated with the same limited tumor cells. Differential proteins on days 13 and 21 were mainly associated with cell adhesion, autophagic cell death, changes in extracellular matrix organization, angiogenesis, and the pentose phosphate pathway. All of these enriched functional processes were reported to contribute to tumor progression and could not be enriched through random allocation analysis.

Conclusions

Our results indicated that (1) the urine proteome reflects changes associated with cancer even with only approximately ten tumor cells in the body and that (2) the urine proteome reflects pathophysiological changes in the body with extremely high sensitivity and provides potential for a very early screening process of clinical patients.
Effects of shokyo (Zingiberis Rhizoma) and kankyo (Zingiberis Processum Rhizoma) on prostaglandin E2production in lipopolysaccharide-treated mouse macrophage RAW264.7 cells
Authors: Ara Toshiaki , Koide Masanori , Kitamura Hiroyuki , Sogawa Norio
Published: September 2019

We previously reported that shokyo and kankyo, which are water-extracted fractions of ginger, reduced LPS-induced PGE2production in human gingival fibroblasts. In this study, we examined the effects of these herbs on LPS-treated mouse macrophage RAW264.7 cells. Both shokyo and kankyo reduced LPS-induced PGE2production in a concentration-dependent manner. Shokyo and kankyo did not inhibit cyclooxygenase (COX) activity, nor did they alter the expression of molecules in the arachidonic acid cascade. In addition, these herbs did not alter NF-κB p65 translocation into nucleus, or phosphorylation of p65 or ERK. These results suggest that shokyo and kankyo inhibit cPLA2activity. Although 6-shogaol produced similar results to those of shokyo and kankyo, the concentration of 6-shogaol required for the reduction of PGE2production were higher than those of 6-shogaol in shokyo and kankyo. Therefore, several gingerols and shogaols other than 6-shogaol may play a role in the reduction of LPS-induced PGE2production. Thus, 6-shogaol, and other gingerols and shogaols inhibit cPLA2activity and reduce LPS-induced PGE2production via a different mechanism from traditional anti-inflammatory drugs. Moreover, kampo medicines that contain shokyo or kankyo are considered to be effective for inflammatory diseases.
Identification of lncRNAs associated with lung squamous cell carcinoma prognosis in the competitive endogenous RNA network
Authors: Qi Lingyu , Zhang Tingting , Yao Yan , Zhuang Jing , Liu Cun , Liu Ruijuan , Sun Changgang
Published: September 2019

Background

Long noncoding RNAs (lncRNAs) play a role in the formation, development, and prognosis of various cancers. Our study aimed to identify prognostic-related lncRNAs in lung squamous cell carcinoma (LUSC), which may provide new perspectives for individualized treatment of patients.

Materials and Methods

The RNA sequencing (lncRNA, microRNA (miRNA), mRNA) data and clinical information related to LUSC were obtained from The Cancer Genome Atlas (TCGA) database. Differentially expressed RNA sequences were used to construct the competitive endogenous RNA (ceRNA) network. In present study, we mainly used two prognostic verification methods, Cox analysis and survival analysis, to identify the prognostic relevance of specific lncRNAs and construct prognostic model of lncRNA.

Results

Datasets on 551 samples of lncRNA and mRNA and 523 miRNA samples were retrieved from the TCGA database. Analysis of the normal and LUSC samples identified 170 DElncRNAs, 331 DEmiRNAs, and 417 DEmRNAs differentially expressed RNAs. The ceRNA network contained 27 lncRNAs, 43 miRNAs, and 11 mRNAs. Furthermore, we identified seven specific lncRNAs (ERVH48-1, HCG9, SEC62-AS1, AC022148.1, LINC00460, C5orf17, LINC00261) as potential prognostic factors after correlation analysis, and five of the seven lncRNAs (AC022148.1, HCG9, LINC00460, C5orf17, LINC00261) constructed a prognostic model of LUSC.

Conclusion

In present study, we identified seven lncRNAs in the ceRNA network that are associated with potential prognosis in LUSC patients, and constructed a prognostic model of LUSC which can be used to assess the prognosis risk of clinical patients. Further biological experiments are needed to elucidate the specific molecular mechanisms underlying them.
Liver slice culture as a model for lipid metabolism in fish
Authors: Harvey Thomas N. , Sandve Simen R. , Jin Yang , Vik Jon Olav , Torgersen Jacob S.
Published: September 2019

Hepatic lipid metabolism is traditionally investigated in vitro using hepatocyte monocultures lacking the complex three-dimensional structure and interacting cell types essential liver function. Precision cut liver slice (PCLS) culture represents an alternative in vitro system, which benefits from retention of tissue architecture. Here, we present the first comprehensive evaluation of the PCLS method in fish (Atlantic salmon, Salmo salar L.) and validate it in the context of lipid metabolism using feeding trials, extensive transcriptomic data, and fatty acid measurements. We observe an initial period of post-slicing global transcriptome adjustment, which plateaued after 3 days in major metabolic pathways and stabilized through 9 days. PCLS fed alpha-linolenic acid (ALA) and insulin responded in a liver-like manner, increasing lipid biosynthesis gene expression. We identify interactions between insulin and ALA, where two PUFA biosynthesis genes that were induced by insulin or ALA alone, were highly down-regulated when insulin and ALA were combined. We also find that transcriptomic profiles of liver slices are exceedingly more similar to whole liver than hepatocyte monocultures, both for lipid metabolism and liver marker genes. PCLS culture opens new avenues for high throughput experimentation on the effect of “novel feed composition” and represent a promising new strategy for studying genotype-specific molecular features of metabolism.
Antimicrobial and Antioxidant Studies of the Leaf Extract and Fractions of Sabicea brevipes Wernham (Rubiaceae)
Authors: Ugorji Chimaobi O. , Ihedioha Janefrances N. , Agbo Matthias O. , Ekere Nwachukwu R. , Nwafor Felix I. , Odoemelam Emmanuel I.
Published: September 2019

Phytochemical analysis, antimicrobial and antioxidant properties of the leaf extract and fractions of Sabicea brevipes were studied. The leaves were defatted and the marc extracted with methanol. The extract was further purified by solvent-solvent partitioning using n-hexane, ethyl acetate and n-butanol to obtain the three solvent fractions. They were screened for phenolics, flavonoids, tannins, saponins, terpenoids, glycosides, and steroids. Total phenolics, flavonoids and tannins were determined quantitatively. The antimicrobial test was screened in vitro by agar diffusion method. Analysis of variance (ANOVA) was used to test for significant difference at p ≤ 0.05 in all study groups. The methanol extract exhibited the most significant amount of phenolics (110.78 ± 1.06 mg GAE/g) while ethyl acetate fraction had the least total phenolics content (50.55 ± 2.91 mg GAE/g). The same trend was observed for the total flavonoids content whereas the methanol extract measured (418.40 ± 14.03 mg QE/g) while ethyl acetate fraction had 192.40 ± 3.06 mg QE/g. Total tannins contents were: methanol extract (102.22 ± 7.58 mg GAE/g) and ethyl acetate (27.33 ± 0.77 mg GAE/g). The antioxidant results showed that the methanol extract had the highest DPPH free radical scavenging ability (93.69%) with half maximal inhibitory concentration (IC50) of 0.601± 0.02 and also highest ferric ion reducing power (50.381 ± 1.56 µmol Fe2+/g). Also, the methanol extract showed high total antioxidant capacity (96.79 ± 0.31 mg AAE) and IC50 of 0.798± 0.01. The antimicrobial results revealed that the methanol extract showed better activity against Escherichia coli, Bacillus subtilis, Pseudomonas aeruginosa, Staphylococcus aureus, and Candida albicans than the solvent fractions at concentrations of 200, 100, 50, 25, 12.5, mg/mL having various inhibition zone diameters (IZDs). The methanol extract and fractions of S. brevipes compared favourably in terms of zone of inhibition and minimum inhibition concentration (MIC) with the standard drug disc (Gentamycin and Ketoconazole) against the tested microorganisms. The MIC of the extract and solvent fractions ranged from 6.31 mg/mL to 50.12 mg/mL. The continual use of the extract of Sabicea brevipes in preventing oxidative stress and in the treatment of common infection is justified by these results.
Trabalho e educação na reprodução social do homem
Authors: Amboni Vanderlei
Published: September 2019

O artigo trata do trabalho e da educação como base ontológica do homem e seu processo de reprodução social. Partimos do trabalho como princípio da vida humana, que nasce em meio à luta pela existência da vida, mas traz a educação como polo de reprodução social mediado pelo trabalho. O estudo situa trabalho e educação como expressão do homem, que necessita (re)produzir sua vida, pois comer, beber, vestir e morar se conquista no domínio da natureza. Para esse fim, o estudo e análise do objeto trabalho e educação tem como referência autores marxistas, onde buscar-se-á destacar as posições teóricas dos mesmos sobre a base material que funda o ser social, mas aprofundamos o estudo do ser social sob o capitalismo.
Benefícios da revolução russa
Authors: Marques Junior Nelson Kautzner
Published: September 2019

O objetivo da revisão foi de apresentar os benefícios da revolução russa referente ao direito trabalhista, na saúde e na educação, no esporte. Até o século XX na Rússia o trabalhador não tinha nenhum direito trabalhista, mas com a revolução russa o povo conquistou vários benefícios – 8 horas de serviço, férias remuneradas etc. A saúde e a educação passaram a ser gratuitos na Rússia revolucionária. Em 1917 Kotov elaborou uma periodização e depois foram feitas outras pesquisas sobre esse tema onde resultaram em outros modelos. Em conclusão, o socialismo é o meio da sociedade se tornar mais igualitária e com melhor qualidade de vida. 
Destruição de forças produtivas e o rebaixamento da formação da classe trabalhadora: o caso da reforma da BNCC do ensino médio
Authors: Taffarel Celi Nelza Zulke , Beltrao José Arlen
Published: September 2019

Este texto objetiva explicar os nexos e relações entre a destruição de forças produtivas e o rebaixamento da formação escolar dos filhos da classe trabalhadora. Discute os elementos centrais e as principais contradições do imperialismo e analisa as mudanças fundamentais promovidas pela lei n. 13.415/2017 e a BNCC do ensino médio, apontando os nexos e relações com o processo de destruição de forças produtivas. Foi possível constatar que esses dispositivos acentuam a tendência de esvaziamento científico do currículo escolar e de desqualificação dos jovens trabalhadores ainda no seu processo de escolarização básica. Além disso, integram o movimento de ofensiva do imperialismo no Brasil, de destruição dos serviços públicos e de forças produtivas.
Randomized controlled trial of TDCS on cognition in 201 seniors with mild neurocognitive disorder
Authors: Lu Hanna , Chan Sandra Sau Man , Chan Wai Chi , Lin Cuichan , Cheng Calvin Pak Wing , Linda Chiu Wa Lam
Published: September 2019

Objective

To examine the efficacy and safety of combined transcranial direct current stimulation (tDCS) and working memory training (WMT) in enhancing the cognitive functions for individuals with mild neurocognitive disorder due to AD (NCD‐AD).

Methods

In this double‐blind, sham‐controlled randomized clinical trial (RCT), 201 patients with NCD‐AD were randomly assigned for a 4‐week intervention of either a combination of tDCS and WMT, sham tDCS and WMT, or tDCS and control cognitive training (CCT). Global cognition and domain‐specific cognitive function were assessed before and after the intervention with Alzheimer's disease assessment scale‐cognitive subscale (ADAS‐Cog), category verbal fluency test, logical memory, digit, and visual span tests.

Results

Study participants did not show intervention group differences in baseline demographics, or cognitive characteristics (ANOVA). Cognitive enhancement was found across three groups after 4 weeks intervention. Combined tDCS‐WMT group showed significantly greater improvement compared with single‐modality groups in delayed recall (P = 0.043, η2 = 0.036) and working memory capacity (P = 0.04, η2 = 0.038) at 4th week, and logical memory at 12th week (P = 0.042, η2 = 0.037). Adverse events, including skin lesions (2.2%), were similar between groups.

Interpretation

tDCS or WMT could be a safe, feasible, and effective intervention for individuals with NCD‐AD. A combination of tDCS and WMT presents greater cognitive enhancement, which may highlight the potential synergistic effects of combined modality intervention on cognition.
Hormonal Dependence and Cancer in Systemic Lupus Erythematosus
Authors: Cobo‐Ibáñez Tatiana , Urruticoechea‐Arana Ana , Rúa‐Figueroa Iñigo , Martín‐Martínez María A. , Ovalles‐Bonilla Juan Gabriel , Galindo María , Calvo‐Alén Jaime , Olivé Alejandro , Fernández‐Nebro Antonio , Menor‐Almagro Raúl , Tomero Eva , Horcada Loreto , Uriarte‐Itzazelaia Esther , Martínez‐Taboada Víctor M. , Andreu José Luis , Boteanu Alina , Narváez Javier , Bohorquez Cristina , Montilla Carlos , Santos Gregorio , Hernández‐Cruz Blanca , Vela Paloma , Salgado Eva , Freire Mercedes , Hernández‐Beriain José Ángel , Díez‐Álvarez Elvira , Expósito Lorena , Fernández‐Berrizbeitia Olaia , Velloso‐Feijoo María Luisa , Ibáñez‐Barceló Mónica , Lozano‐Rivas Nuria , Bonilla Gema , Moreno Mireia , Raya Enrique , Quevedo‐Vila Víctor Eliseo , Vázquez‐Rodríguez Tomas Ramón , Ibáñez‐Ruan Jesús , Muñoz‐Fernández Santiago , Sánchez‐Alonso Fernando , Pego‐Reigosa José María
Published: September 2019

Objective

To estimate the incidence and analyze any cancer‐associated factors in patients with systemic lupus erythematosus (SLE), differentiating between hormone‐sensitive (HS) and non‐HS cancers.

Methods

This was a retrospective multicenter study of a patient cohort from the Systemic Lupus Erythematosus Registry of the Spanish Society of Rheumatology. Included were the first cancer post‐SLE diagnosis, clinical and sociodemographic information, cumulative damage, severity, comorbidities, treatments, and refractoriness. Cancers were classified as HS (prostate, breast, endometrium, and ovarian) and non‐HS (the remainder). The standardized incidence ratio (SIR) was calculated and logistic regression models were built.

Results

A total of 3,539 patients (90.4% women) were included, 154 of whom had cancer (91% female), and 44 had HS cancer (100% female). The cancer SIR was 1.37 (95% confidence interval [95% CI] 1.15–1.59), with higher values in women age <65 years (SIR 2.38 [95% CI 1.84–2.91]). The SIR in women with HS versus non‐HS cancer was 1.02 (95% CI 0.13–1.91) and 1.93 (95% CI 0.98–2.89). In HS versus non‐HS cancers, SLE diagnostic age (odds ratio [OR] 1.04 [P = 0.002] versus 1.04 [P = 0.019]), and period of disease evolution (OR 1.01 [P < 0.001] versus 1.00 [P = 0.029]) were associated with cancer. The Systemic Lupus International Collaborating Clinics/American College of Rheumatology Damage Index (OR 1.27 [P = 0.022]) and angiotensin‐converting enzyme (ACE) inhibitor prescriptions (OR 2.87 [P = 0.048]) were associated with non‐HS cancers.

Conclusion

Cancer incidence in patients with SLE was higher than in the Spanish population, particularly among young women. This increase might be due to non‐HS cancers, which would be associated with SLE involving greater cumulative damage where more ACE inhibitors are prescribed.
A Lithium‐Ion Pump Based on Piezoelectric Effect for Improved Rechargeability of Lithium Metal Anode
Authors: Xiang Jingwei , Cheng Zexiao , Zhao Ying , Zhang Bao , Yuan Lixia , Shen Yue , Guo Zezhou , Zhang Yi , Jiang Jianjun , Huang Yunhui
Published: September 2019

Lithium metal is widely studied as the “crown jewel” of potential anode materials due to its high specific capacity and low redox potential. Unfortunately, the Li dendrite growth limits its commercialization. Previous research has revealed that the uniform Li‐ion flux on electrode surface plays a vital role in achieving homogeneous Li deposition. In this work, a new strategy is developed by introducing a multifunctional Li‐ion pump to improve the homogenous distribution of Li ions. Via coating a β‐phase of poly(vinylidene fluoride) (β‐PF) film on Cu foil (Cu@β‐PF), a piezoelectric potential across such film is established near the electrode surface because of its piezoelectric property, which serves as a driving force to regulate the migration of Li ions across the film. As a result, uniform Li‐ion distribution is attained, and the Cu@β‐PF shows coulombic efficiency around 99% throughout 200 cycles. Meanwhile, the lithium‐sulfur full cell paired with Li‐Cu@β‐PF anode exhibits excellent performance. This facile strategy via regulating the Li‐ion migration provides a new perspective for safe and reliable Li metal anode.
Negative Capacitance for Electrostatic Supercapacitors
Authors: Hoffmann Michael , Fengler Franz Paul Gustav , Max Benjamin , Schroeder Uwe , Slesazeck Stefan , Mikolajick Thomas
Published: September 2019

The increasing demand for efficient storage of electrical energy is one of the main challenges in the transformation toward a carbon neutral society. While electrostatic capacitors can achieve much higher power densities compared to other storage technologies like batteries, their energy densities are comparatively low. Here, it is proposed and demonstrated that negative capacitance, which is present in ferroelectric materials, can be used to improve the energy storage of capacitors beyond fundamental limits. While negative capacitance was previously mainly considered for low power electronics, it is shown that ferroelectric/dielectric capacitors using negative capacitance are promising for energy storage applications. Compared to earlier results using (anti)ferroelectric materials for electrostatic energy storage, much higher efficiencies of more than 95% even for ultrahigh energy densities beyond 100 J cm−3 are demonstrated using nonepitaxial thin films suitable for integration on 3D substrates. Stable operation up to 150 °C and 108 charging/discharging cycles is further demonstrated.
Interfacial Super‐Assembled Porous CeO2/C Frameworks Featuring Efficient and Sensitive Decomposing Li2O2 for Smart Li–O2 Batteries
Authors: Hou Yue , Wang Jun , Liu Jiaqing , Hou Chuanxin , Xiu Zhaohong , Fan Yuqi , Zhao Lanling , Zhai Yanjie , Li Hongyu , Zeng Jie , Gao Xiang , Zhou Shan , Li Dongwei , Li Yong , Dang Feng , Liang Kang , Chen Pu , Li Changming , Zhao Dongyuan , Kong Biao
Published: September 2019

The Li–O2 battery (LOB) represents a promising candidate for future electric vehicles owing to its outstanding energy density. However, the practical application of LOB cells is largely blocked by the poor cycling performance of cathode materials. Herein, an ultralong 440‐cycle life of an LOB cell is achieved using CeO2 nanocubes super‐assembled on an inverse opal carbon matrix as the cathode material without any additives. CeO2 is proved to be effective for the complete and sensitive decomposition of loosely stacked Li2O2 films during the oxygen evolution reaction process and full accommodation of volume changes caused by the fast growth of Li2O2 films during the oxygen reduction reaction process. The super‐assembled porous CeO2/C frameworks satisfy critical requirements including controlled size, morphology, high Ce3+/Ce4+ ratio, and efficient volume change accommodation, which dramatically increase the cycle life of LOB cell to 440 cycles. This study reveals the design strategy for high performance CeO2 catalyst cathodes for LOB cells and the generation mechanisms of Li2O2 films during the discharge process by using density functional theory calculations, showing new avenues for improving the future smart design of CeO2‐based cathode catalysts for Li–O2 batteries.
Surface Engineering of 3D Gas Diffusion Electrodes for High‐Performance H2 Production with Nonprecious Metal Catalysts
Authors: Sanchez Joel , Hellstern Thomas R. , King Laurie A. , Jaramillo Thomas F.
Published: September 2019

In this work, a methodology is demonstrated to engineer gas diffusion electrodes for nonprecious metal catalysts. Highly active transition metal phosphides are prepared on carbon‐based gas diffusion electrodes with low catalyst loadings by modifying the O/C ratio at the surface of the electrode. These nonprecious metal catalysts yield extraordinary performance as measured by low overpotentials (51 mV at −10 mA cm−2), unprecedented mass activities (>800 A g−1 at 100 mV overpotential), high turnover frequencies (6.96 H2 s−1 at 100 mV overpotential), and high durability for a precious metal‐free catalyst in acidic media. It is found that a high O/C ratio induces a more hydrophilic surface directly impacting the morphology of the CoP catalyst. The improved hydrophilicity, stemming from introduced oxyl groups on the carbon electrode, creates an electrode surface that yields a well‐distributed growth of cobalt electrodeposits and thus a well‐dispersed catalyst layer with high surface area upon phosphidation. This report demonstrates the high‐performance achievable by CoP at low loadings which facilitates further cost reduction, an important part of enabling the large‐scale commercialization of non‐platinum group metal catalysts. The fabrication strategies described herein offer a pathway to lower catalyst loading while achieving high efficiency and promising stability on a 3D electrode.
Nonlinear modeling of saguaro growth rates reveals the importance of temperature for size‐dependent growth
Authors: Félix‐Burruel Ricardo E. , Larios Eugenio , Bustamante Enriquena , Búrquez Alberto
Published: September 2019

Premise

The saguaro cactus is an iconic species of the Sonoran Desert. Its individual growth rates have been investigated for over 100 years. Its growth dynamics have been studied using phenomenological models intended to estimate growth, but not to understand the underlying biological processes. Most studies have suggested summer rainfall as the sole factor determining saguaro growth, overlooking the influence of other factors related to the process of growth.

Methods

We analyzed the annual growth rates for 13 saguaro populations in the Sonoran Desert using nonlinear models. These are better suited to analyze growth since they consider the fact that maximum growth rates diminish just before the onset of reproduction. We related model parameters to the local climate.

Results

The most parsimonious model was the Ricker function that described growth considering cactus decline with age. Variance in temperature, rather than precipitation, was more closely related to growth. Higher variance in temperature at the beginning of the warm season was detrimental to saguaro growth.

Conclusions

Simple nonlinear equations modeled growth rate using biologically interpretable parameters related to climate factors. Because the temperature is projected to increase in both mean and variance by climate change, the population dynamics of this iconic cactus are likely to be affected.
The onset of xylogenesis in Smith fir is not related to outer bark thickness
Authors: Li Xiaoxia , Rossi Sergio , Liang Eryuan
Published: September 2019

Premise

The resumption of stem growth varies across the ontogenetic development of trees. Compared with younger trees, older ones have thicker outer bark with a temperature‐insulating effect that could potentially prevent the stem from warming in the spring. However, the question of whether xylogenesis in old trees is influenced by the thick bark still remains unresolved.

Methods

We investigated the onset of xylogenesis across the ontogenetic development of Smith fir (Abies georgei var. smithii) trees in the Sygera Mountains, southeastern Tibetan Plateau. The outer bark of older trees was also removed. Xylogenesis was monitored in microcores we collected every 3 days during May and June in 2017.

Results

Xylogenesis began in late May in young (<50 yr) and mature (50–100 yr) trees, 1 week earlier than in adult (>100–150 yr) and old (>150–200 yr) trees. Older (>200 yr) trees had the latest onset of xylogenesis, 2 weeks after young trees. The resumption of xylogenesis was similar between the control and bark‐removed trees.

Conclusions

Growth resumption was delayed in older and bigger trees. Outer bark did not affect the onset of xylogenesis, which indicated that the delayed resumption of growth during the lifespan of trees could be more related to endogenous factors than to an insulating effect of the thick bark of older individuals.
Odontogenic sinusitis is a common cause of unilateral sinus disease with maxillary sinus opacification
Authors: Turfe Zaahir , Ahmad Abid , Peterson Edward I. , Craig John R.
Published: September 2019

Background

Unilateral sinus disease (USD) carries a broader differential diagnosis than bilateral sinus disease, including various inflammatory and neoplastic conditions. Odontogenic sinusitis (ODS) is a common cause of unilateral maxillary sinusitis, but few studies have examined its incidence among all USD etiologies. The main purposes of this prospective study were to determine the incidences of ODS and other etiologies causing USD with complete maxillary sinus opacification on computed tomography (CT), and to compare CT features of ODS and non‐odontogenic USD patients. In addition, clinical features of the ODS cohort are described.

Methods

A prospective case series of 134 patients with USD with complete maxillary sinus opacification on CT was conducted from August 2015 to November 2018. Based on nasal endoscopy, sinus CT, and dental examination and imaging, patients were categorized as having unilateral ODS or non‐odontogenic USD. Patients with non‐odontogenic USD were categorized as inflammatory or neoplastic. Demographic and clinical data were reported for ODS patients.

Results

Of the 134 patients, 45% had ODS, 36% had non‐odontogenic inflammatory conditions, 17% had inverted papilloma, and 2% had malignancies. Of the 60 ODS cases, 86.7% were associated with middle meatal purulence on nasal endoscopy. On CT, 88.3% had extramaxillary sinus disease extension, and 65.5% of CT reports made no mention of dental pathology.

Conclusion

ODS caused nearly 50% of all USD cases with maxillary sinus opacification on CT, and was the most common individual etiology. ODS was frequently associated with anterior ethmoid and frontal sinus disease on CT, and middle meatal purulence on nasal endoscopy.
Defect‐Mediated Ordering of Condensed Water Structures in Microporous Zeolites
Authors: Bukowski Brandon C. , Bates Jason S. , Gounder Rajamani , Greeley Jeffrey
Published: September 2019

Ab‐initio molecular dynamics simulations and transmission infrared spectroscopy are employed to characterize the structure of water networks in defect‐functionalized microporous zeolites. Thermodynamically stable phases of clustered water molecules are localized at some of the defects in zeolite Beta, which include catalytic sites such as framework Lewis acidic Sn atoms in closed and hydrolyzed‐open forms, as well as silanol nests. These water clusters compete with ideal gas‐like structures at low water densities and pore‐filling phases at higher water densities, with the equilibrium phase determined by the water chemical potential. The physical characteristics of these phases are determined by the defect identity, with the local binding and orientation of hydroxyl moieties around the defects playing a central role. The results suggest general principles for how the structure of polar solvents in microporous solid acids is influenced by local defect functionalization, and the thermodynamic stability of the condensed phases surrounding such sites, in turn, implies that the catalysis of Lewis acids will be influenced by local water ordering.
Selective Catalytic Chemistry at Rhodium(II) Nodes in Bimetallic Metal–Organic Frameworks
Authors: Shakya Deependra M. , Ejegbavwo Otega A. , Rajeshkumar Thayalan , Senanayake Sanjaya D. , Brandt Amy J. , Farzandh Sharfa , Acharya Narayan , Ebrahim Amani M. , Frenkel Anatoly I. , Rui Ning , Tate Gregory L. , Monnier John R. , Vogiatzis Konstantinos D. , Shustova Natalia B. , Chen Donna A.
Published: September 2019

We report the first study of a gas‐phase reaction catalyzed by highly dispersed sites at the metal nodes of a crystalline metal–organic framework (MOF). Specifically, CuRhBTC (BTC3−=benzenetricarboxylate) exhibited hydrogenation activity, while other isostructural monometallic and bimetallic MOFs did not. Our multi‐technique characterization identifies the oxidation state of Rh in CuRhBTC as +2, which is a Rh oxidation state that has not previously been observed for crystalline MOF metal nodes. These Rh2+ sites are active for the catalytic hydrogenation of propylene to propane at room temperature, and the MOF structure stabilizes the Rh2+ oxidation state under reaction conditions. Density functional theory calculations suggest a mechanism in which hydrogen dissociation and propylene adsorption occur at the Rh2+ sites. The ability to tailor the geometry and ensemble size of the metal nodes in MOFs allows for unprecedented control of the active sites and could lead to significant advances in rational catalyst design.
Über bislang nicht beachtete Parallelen in der Reaktivität von Arinen und Donor‐Akzeptor‐Cyclopropanen
Authors: Werz Daniel B. , Biju Akkattu T.
Published: September 2019

Arine und Donor‐Akzeptor‐substituierte (D‐A‐)Cyclopropane sind zwei Klassen gespannter Systeme mit einer Vielzahl an möglichen Anwendungen in der organischen Synthese. In den letzten beiden Jahrzehnten hat die Chemie dieser beiden Spezies eine Renaissance erlebt, vor allem wegen der milden und zuverlässigen Methoden zu ihrer Herstellung oder Aktivierung. In der Regel führen Arine als leicht polarisierbare Systeme zur 1,2‐Disubstitution, während D‐A‐Cyclopropane als polarisierte Systeme zur 1,3‐Disubstitution neigen und dabei auffällige Ähnlichkeiten aufweisen. Die Umsetzungen mit 1,2‐ und 1,3‐Dipolen führen zu cyclischen Strukturen. Die mit Arinen entstehenden viergliedrigen cyclischen Intermediate können weiterreagieren, während die analogen fünfgliedrigen Cyclen hervorgehend aus D‐A‐Cyclopropanen meist die finalen Endprodukte darstellen. Es gibt jedoch einige Fälle, in denen sich diese Zwischenprodukte überraschend unterschiedlich verhalten. Dieser Kurzaufsatz zielt darauf ab, die Parallelen in der Reaktivität von Arinen und D‐A‐Cyclopropanen aufzuzeigen und somit Licht auf die bisher vernachlässigten Ähnlichkeiten dieser beiden reaktiven Spezies zu werfen.
Bifunctional Metal Nanocrystals for Catalyzing and Reporting on Chemical Reactions
Authors: Shi Shi , Qin Dong
Published: September 2019

Bifunctional nanocrystals with integrated plasmonic and catalytic activities hold great promise for analyzing chemical reactions by in situ surface‐enhanced Raman spectroscopy. This Minireview gives a brief introduction to the general strategies for designing such nanocrystals, followed by four typical examples, including their fabrication, characterization, and potential limitation. We then use the reduction of 4‐nitrothiophenol and oxidation of 4‐aminothiophenol as two model systems to demonstrate the capabilities of these bifunctional nanocrystals to monitor chemical reactions for the elucidation of reaction mechanisms and measurement of kinetics. We conclude with perspectives on further development of these bifunctional nanocrystals into a viable platform for investigating other types of catalytic reactions.
Loading‐Dependent Structural Model of Polymeric Micelles Encapsulating Curcumin by Solid‐State NMR Spectroscopy
Authors: Pöppler Ann‐Christin , Lübtow Michael M. , Schlauersbach Jonas , Wiest Johannes , Meinel Lorenz , Luxenhofer Robert
Published: September 2019

Detailed insight into the internal structure of drug‐loaded polymeric micelles is scarce, but important for developing optimized delivery systems. We observed that an increase in the curcumin loading of triblock copolymers based on poly(2‐oxazolines) and poly(2‐oxazines) results in poorer dissolution properties. Using solid‐state NMR spectroscopy and complementary tools we propose a loading‐dependent structural model on the molecular level that provides an explanation for these pronounced differences. Changes in the chemical shifts and cross‐peaks in 2D NMR experiments give evidence for the involvement of the hydrophobic polymer block in the curcumin coordination at low loadings, while at higher loadings an increase in the interaction with the hydrophilic polymer blocks is observed. The involvement of the hydrophilic compartment may be critical for ultrahigh‐loaded polymer micelles and can help to rationalize specific polymer modifications to improve the performance of similar drug delivery systems.
Hydrothermal liquefaction of macroalgae for the production of renewable biofuels
Authors: Raikova Sofia , Allen Michael J. , Chuck Christopher J.
Published: September 2019

In all biorefinery systems, excess water represents a key challenge, and its removal by drying is often a necessary and crucial pre‐treatment. Second‐generation feedstocks have often fallen at this hurdle, particularly microalgae‐derived biomasses, which require extensive (and costly) dewatering. Hydrothermal liquefaction (HTL) has gained increasing attention in recent years as a technology that uses the water present in the feedstock as a versatile reaction medium, which functions as a solvent, reactant, and catalyst for a cascade of organic reactions. Converting organic biomasses into oil, aqueous, solid, and gas fractions, the development of HTL provides the opportunity to exploit previously unsuitable biomasses in a versatile bio‐refinery approach. Marine macroalgae (seaweeds) offer a sustainable source of renewable biomass, which require no land or freshwater to cultivate or harvest. With 70% of the surface of the planet covered in seawater and levels of eutrophication increasing, seaweeds are an underutilized resource with excellent potential for relieving the pressure on fossil resources. Hitherto, this exploitation has been hindered by a lack of suitable and economical processing tools. Here we review the potential for applying HTL to processing marine macroalgae and discuss the potential products and services that can be derived from this potential biorefinery system. © 2019 Society of Chemical Industry and John Wiley & Sons, Ltd.
Thermostability enhancement of the Pseudomonas fluorescens esterase I by in vivo folding selection in Thermus thermophilus
Authors: Mate Diana M. , Rivera Noé R. , Sanchez‐Freire Esther , Ayala Juan A. , Berenguer José , Hidalgo Aurelio
Published: September 2019

Prolonged stability is a desired property for the biotechnological application of enzymes since it allows its reutilization, contributing to making biocatalytic processes more economically competitive with respect to chemical synthesis. In this study, we have applied selection by folding interference at high temperature in Thermus thermophilus to obtain thermostable variants of the esterase I from Pseudomonas fluorescens (PFEI). The most thermostable variant (Q11L/A191S) showed a melting temperature (Tm) of 77.3 ± 0.1°C (4.6°C higher than the wild‐type) and a half‐life of over 13 hr at 65°C (7.9‐fold better than the wild‐type), with unchanged kinetic parameters. Stabilizing mutations Q11L and A191S were incorporated into PFEI variant L30P, previously described to be enantioselective in the hydrolysis of the (−)‐enantiomer of the Vince lactam. The final variant Q11L/L30P/A191S showed a significant improvement in thermal stability (Tm of 80.8 ± 0.1°C and a half‐life of 65 min at 75°C), while retaining enantioselectivity (E > 100). Structural studies revealed that A191S establishes a hydrogen bond network between a V‐shaped hairpin and the α/β hydrolase domain that leads to higher rigidity and thus would contribute to explaining the increase in stability.
Optimization of the Cellulase−Ultrasonic Synergistic Extraction Conditions of Polysaccharides from Lenzites betulina
Authors: Guo Lei , Tan Da‐Cong , Hui Fu‐Yi , Gu Fan , Xiao Kun‐Min , Hua Yan
Published: September 2019

Lenzites betulina has been recognized as a rich source of chemical components, including polysaccharides, sterides and sugar alcohols. In this study, cellulase−ultrasonic synergistic extraction method was applied to extract polysaccharides from L. betulina, and the response surface methodology was used to optimize the extraction conditions. The eight basic factors affecting extraction yield were evaluated by Plackett−Burman design (PBD). Then, the four important factors significantly affecting the yield of polysaccharides from L. betulina, including enzymolysis temperature, enzymolysis time, ultrasound time and ultrasound temperature, were optimized by Box−Behnken design (BBD). Maximum extraction yield of L. betulina polysaccharides was 13.64±0.09 % at a cellulase dosage of 0.8 %, enzymolysis temperature of 60 °C, enzymolysis time of 180 min, pH of 4.5, liquid‐solid ratio of 45 ml/g, ultrasound power of 300 W, ultrasound time of 20 min and ultrasound temperature of 45 °C. Subsequently, the characteristic structure of crude polysaccharides was determined by FT‐IR. Results indicated that cellulase−ultrasonic synergistic treatment is suitable for L. betulina polysaccharides extraction, and it has good prospect for development and utilization.
Influence of Carbon Coating on Intercalation Kinetics and Transport Properties of LiFePO4
Authors: Iarchuk Anna R. , Nikitina Victoria A. , Karpushkin Evgeny A. , Sergeyev Vladimir G. , Antipov Evgeny V. , Stevenson Keith J. , Abakumov Artem M.
Published: September 2019

We report on a comparative study of Li+ intercalation kinetics for LiFePO4 materials with polydopamine‐derived and glucose‐derived carbon coatings. We demonstrate that the uniform polydopamine‐derived carbon coating affects the charge transfer rates and transport properties (electronic conductivity) of composite electrodes only slightly (compared to the inhomogeneous glucose‐derived coatings), whereas much more pronounced effects are observed for the apparent diffusion coefficients and nucleation barriers. Thick and uniform carbon surface layers cause a sharp decrease in the ionic diffusion coefficients, which results in the loss of capacity at higher charge/discharge rates for LiFePO4 composite electrodes. The new phase nucleation rates are also demonstrated to decrease significantly for the samples with thicker coatings inducing higher potential differences between charge and discharge curves. The analysis of the rate determining factors for the LiFePO4 electrodes points to the rate limitations induced by the slow nucleation and slow ionic diffusion, whereas the formation of a polydopamine‐derived uniform carbon layer tends to hinder the (de)intercalation reaction and does not provide additional benefits compared to glucose‐derived carbon coatings comprising conductive yet inhomogeneous layers.