bluuebunny/crossref_metadata_2025 huggingface dataset:
Martian low‐altitude magnetic topology deduced from MAVEN/SWEA observations
Authors: Xu Shaosui , Mitchell David , Liemohn Michael , Fang Xiaohua , Ma Yingjuan , Luhmann Janet , Brain David , Steckiewicz Morgane , Mazelle Christian , Connerney Jack , Jakosky Bruce
Published: January 2017

The Mars Atmosphere and Volatile Evolution mission has obtained comprehensive particle and magnetic field measurements. The Solar Wind Electron Analyzer provides electron energy‐pitch angle distributions along the spacecraft trajectory that can be used to infer magnetic topology. This study presents pitch angle‐resolved electron energy shape parameters that can distinguish photoelectrons from solar wind electrons, which we use to deduce the Martian magnetic topology and connectivity to the dayside ionosphere. Magnetic topology in the Mars environment is mapped in three dimensions for the first time. At low altitudes (<400 km) in sunlight, the northern hemisphere is found to be dominated by closed field lines (both ends intersecting the collisional atmosphere), with more day‐night connections through cross‐terminator closed field lines than in the south. Although draped field lines with ~100 km amplitude vertical fluctuations that intersect the electron exobase (~160–220 km) in two locations could appear to be closed at the spacecraft, a more likely explanation is provided by crustal magnetic fields, which naturally have the required geometry. Around 30% of the time, we observe open field lines from 200 to 400 km, which implies three distinct topological layers over the northern hemisphere: closed field lines below 200 km, open field lines with foot points at lower latitudes that pass over the northern hemisphere from 200 to 400 km, and draped interplanetary magnetic field above 400 km. This study also identifies open field lines with one end attached to the dayside ionosphere and the other end connected with the solar wind, providing a path for ion outflow.
Double sporadic metal layers as observed by colocated Fe and Na lidars at Wuhan, China
Authors: Wang Xiaodong , Yi Fan , Huang Kaiming
Published: January 2017

In this paper, we report a set of double sporadic layer events observed by Fe and Na lidars over Wuhan, China. The two sporadic metal layers above normal layer were named as upper and middle sporadic metal layers, respectively. In these events, the upper, middle, and normal Fe layers presented altitude separately. There were nine double sporadic Fe events observed in 163 nights during 2010–2013. Eight of the nine events were observed in summer. The maximum ratios of peak density for upper and middle sporadic Fe layers to normal Fe layer were up to ~375% and ~225%, respectively. The peak altitudes of upper (middle) sporadic Fe layers were in the range of 102–107 km (95–98.5 km). The double sporadic Fe layers lasted more than 2 h. Interestingly, we found that density enhancement occurred simultaneously in upper, middle, and normal Fe layers on two events. On the nine Fe events, there existed five nights of colocated Na lidar observations. We found that double sporadic Na and Fe layers simultaneously appeared. They presented similar structures, altitudes, and temporal variations in all five compared events. A little different from Fe, the middle sporadic Na layer was not separated from Na main layer maybe for the wide altitude range of Na main layer. The ratios of upper (middle) sporadic Fe and Na peak values were in the range of 6.6–52 (0.57–6.58). While the exact formation mechanism responsible for double sporadic metal layers is still unclear, some possible explanations and corresponding observations are discussed.
Modeling the compressibility of Saturn's magnetosphere in response to internal and external influences
Authors: Sorba A. M. , Achilleos N. A. , Guio P. , Arridge C. S. , Pilkington N. M. , Masters A. , Sergis N. , Coates A. J. , Dougherty M. K.
Published: January 2017

The location of a planetary magnetopause is principally determined by the balance between solar wind dynamic pressure DP and magnetic and plasma pressures inside the magnetopause boundary. Previous empirical studies assumed that Saturn's magnetopause standoff distance varies as
and measured a constant compressibility parameter α corresponding to behavior intermediate between a vacuum dipole appropriate for Earth (α≈6) and a more easily compressible case appropriate for Jupiter (α≈4). In this study we employ a 2‐D force balance model of Saturn's magnetosphere to investigate magnetospheric compressibility in response to changes in DP and global hot plasma content. For hot plasma levels compatible with Saturn observations, we model the magnetosphere at a range of standoff distances and estimate the corresponding DP values by assuming pressure balance across the magnetopause boundary. We find that for “average” hot plasma levels, our estimates of α are not constant with DP but vary from ∼4.8 for high DP conditions, when the magnetosphere is compressed (≤25 RS), to ∼3.5 for low DP conditions. This corresponds to the magnetosphere becoming more easily compressible as it expands. We find that the global hot plasma content influences magnetospheric compressibility even at fixed DP, with α estimates ranging from ∼5.4 to ∼3.3 across the range of our parameterized hot plasma content. We suggest that this behavior is predominantly driven by reconfiguration of the magnetospheric magnetic field into a more disk‐like structure under such conditions. In a broader context, the compressibility of the magnetopause reveals information about global stress balance in the magnetosphere.
Daytime ion and electron temperatures in the topside ionosphere at middle latitudes
Authors: Hsu Chih‐Te , Heelis Roderick A.
Published: January 2017

In the topside ionosphere during the daytime, the thermal electrons are directly heated by photoelectron fluxes from the local and conjugate hemispheres. The heat is lost primarily through conduction to the regions below where collisions with the ions provide the cooling. Ions are heated by collisions with both the electrons and ions and are cooled primarily by conduction to lower altitudes where the heat is lost to collisions with the neutral gas. Here we examine the effects of ion composition on the ion and electron temperatures in the midlatitude topside ionosphere during daytime using data from the Defense Meteorological Satellite Program F15 satellite in 2004–2006. The variations of electron and ion temperature with plasma density and composition indicate how the heat is exchanged between the different constituent ions and the role played by the solar zenith angle and the solar ionizing flux (F10.7). The observations show that the daytime temperature difference between the O+ and electron is smallest when the fractional contribution of H+ is the highest. In such an environment the electrons transfer heat to the H+ then to the O+ through ion‐ion collisions.
Gradual reduction in ionospheric F2 region before the 2013 Lushan earthquake: Contributed to the forthcoming earthquake or solar activity?
Authors: Xu T. , Feng J. , Wu J. , Ge S. C. , Hu Y. L.
Published: January 2017

Ionospheric anomalies before earthquakes during geomagnetic quiet conditions have been extensively discussed due to the importance of earthquake prediction. However, because of the high variability of ionosphere, a real caution should be adopted before attributing the observations to seismo‐ionospheric precursors. In an investigation of contradictory results in ionospheric variation before the 2013 Lushan earthquake, we examine the ionospheric variation versus solar activity. In order to assess the influence of solar activity of 27 day periodicity on ionospheric variation, a quadratic regression model is developed by using the data of F2 layer critical frequency (foF2) in April of 2008–2014. Using the model, ionospheric variation before the 2013 Lushan earthquake is analyzed. The results show that foF2 was strongly correlated with solar activity index, F10.7, and had a low correlation with the remaining by eliminating the contribution of solar radiation, which indicates that the gradual reduction in foF2 before the earthquake was contributed to the variation of solar radiation rather than the forthcoming earthquake.
Laboratory observations of temperature and humidity dependencies of nucleation and growth rates of sub‐3 nm particles
Authors: Yu Huan , Dai Liang , Zhao Yi , Kanawade Vijay P. , Tripathi Sachchida N. , Ge Xinlei , Chen Mindong , Lee Shan‐Hu
Published: January 2017

Temperature and relative humidity (RH) are the most important thermodynamic parameters in aerosol formation, yet laboratory studies of nucleation and growth dependencies on temperature and RH are lacking. Here we report the experimentally observed temperature and RH dependences of sulfuric acid aerosol nucleation and growth. Experiments were performed in a flow tube in the temperature range from 248 to 313 K, RH from 0.8% to 79%, and relative acidity (RA) of sulfuric acid from 6 × 10−5 to 0.38 (2 × 107–109 cm−3). The impurity levels of base compounds were determined to be NH3 < 23 pptv (parts per thousand by volume), methylamine < 1.5 pptv, and dimethylamine < 0.52 pptv. Our results showed that low temperatures favor nucleation at fixed sulfuric acid concentration but impede nucleation when RA is fixed. It is also shown that binary nucleation of sulfuric acid and water is negligible in planetary boundary layer temperature and sulfuric acid ranges. An empirical algorithm was derived to correlate the nucleation rate with RA, RH, and temperature together. Collision‐limited condensation of free‐sulfuric acid molecules fails to predict the observed growth rate in the sub‐3 nm size range, as well as its dependence on temperature and RH. This suggests that evaporation, sulfuric acid hydration, and possible involvement of other ternary molecules should be considered for the sub‐3 nm particle growth.
Polyanion‐Type Electrode Materials for Sodium‐Ion Batteries
Authors: Ni Qiao , Bai Ying , Wu Feng , Wu Chuan
Published: January 2017

Sodium‐ion batteries, representative members of the post‐lithium‐battery club, are very attractive and promising for large‐scale energy storage applications. The increasing technological improvements in sodium‐ion batteries (Na‐ion batteries) are being driven by the demand for Na‐based electrode materials that are resource‐abundant, cost‐effective, and long lasting. Polyanion‐type compounds are among the most promising electrode materials for Na‐ion batteries due to their stability, safety, and suitable operating voltages. The most representative polyanion‐type electrode materials are Na3V2(PO4)3 and NaTi2(PO4)3 for Na‐based cathode and anode materials, respectively. Both show superior electrochemical properties and attractive prospects in terms of their development and application in Na‐ion batteries. Carbonophosphate Na3MnCO3PO4 and amorphous FePO4 have also recently emerged and are contributing to further developing the research scope of polyanion‐type Na‐ion batteries. However, the typical low conductivity and relatively low capacity performance of such materials still restrict their development. This paper presents a brief review of the research progress of polyanion‐type electrode materials for Na‐ion batteries, summarizing recent accomplishments, highlighting emerging strategies, and discussing the remaining challenges of such systems.
Rational Design of Metal‐Organic Framework Derived Hollow NiCo2O4 Arrays for Flexible Supercapacitor and Electrocatalysis
Authors: Guan Cao , Liu Ximeng , Ren Weina , Li Xin , Cheng Chuanwei , Wang John
Published: January 2017

Metal‐organic frameworks (MOFs) are promising porous precursors for the construction of various functional materials for high‐performance electrochemical energy storage and conversion. Herein, a facile two‐step solution method to rational design of a novel electrode of hollow NiCo2O4 nanowall arrays on flexible carbon cloth substrate is reported. Uniform 2D cobalt‐based wall‐like MOFs are first synthesized via a solution reaction, and then the 2D solid nanowall arrays are converted into hollow and porous NiCo2O4 nanostructures through an ion‐exchange and etching process with an additional annealing treatment. The as‐obtained NiCo2O4 nanostructure arrays can provide rich reaction sites and short ion diffusion path. When evaluated as a flexible electrode material for supercapacitor, the as‐fabricated NiCo2O4 nanowall electrode shows remarkable electrochemical performance with excellent rate capability and long cycle life. In addition, the hollow NiCo2O4 nanowall electrode exhibits promising electrocatalytic activity for oxygen evolution reaction. This work provides an example of rational design of hollow nanostructured metal oxide arrays with high electrochemical performance and mechanical flexibility, holding great potential for future flexible multifunctional electronic devices.
Technical Efficiency in Chilean Agribusiness Industry: A Metafrontier Approach
Authors: Lakner Sebastian , Brenes‐Muñoz Thelma , Brümmer Bernhard
Published: January 2017

This study models the technical efficiency in the Chilean agribusiness industry between 2001 and 2007 by taking into consideration the structural differences between the different subsectors meat, fruit & vegetables, dairy, milling, and bakery. We analyze firm data from the Annual National Industrial Survey (ENIA) totaling 2,940 observations using a stochastic frontier model combined with a metafrontier model. We observe dynamic developments in the subsectors meat, fruit & vegetables, and dairy, with a pronounced export‐orientation. We show that especially meat and fruit & vegetables firms have experienced positive technological change, whereas dairy firms are exhibiting a slight decrease in efficiency and technical change. The milling and bakery subsectors, which mainly produce for the domestic market, show a rather constant status in efficiency and technical change. The results confirm that an in‐depth analysis of subsectors is necessary to evaluate the competitiveness of the agribusiness industry in Chile. [EconLit citations: D24; Q13].
How Much Do Consumers Value Protected Designation of Origin Certifications? Estimates of willingness to Pay for PDO Dry‐Cured Ham in Italy
Authors: Garavaglia Christian , Mariani Paolo
Published: January 2017

This study investigates consumers’ preferences and willingness to pay (WTP) for protected designation of origin certifications. First, the paper proposes the use of a new index in food studies to measure WTP. We focus on dry‐cured ham in Italy. Our results add a geographical dimension to studies of consumer preferences by providing evidence of the existence of differences based on place of residence. Consumers who live in the same area where certified ham is produced are willing to pay a lower premium price than consumers living farther away are willing to pay: the closer consumers live to the area of production of the certified product, the less they refer to extrinsic certification cues [EconLit citations: Q11; D12; C35].
Chronic lymphocytic leukemia: A prognostic model comprising only two biomarkers (IGHV mutational status and FISH cytogenetics) separates patients with different outcome and simplifies the CLL‐IPI
Authors: Delgado Julio , Doubek Michael , Baumann Tycho , Kotaskova Jana , Molica Stefano , Mozas Pablo , Rivas‐Delgado Alfredo , Morabito Fortunato , Pospisilova Sarka , Montserrat Emili
Published: January 2017

Rai and Binet staging systems are important to predict the outcome of patients with chronic lymphocytic leukemia (CLL) but do not reflect the biologic diversity of the disease nor predict response to therapy, which ultimately shape patients' outcome. We devised a biomarkers‐only CLL prognostic system based on the two most important prognostic parameters in CLL (i.e., IGHV mutational status and fluorescence in situ hybridization [FISH] cytogenetics), separating three different risk groups: (1) low‐risk (mutated IGHV + no adverse FISH cytogenetics [del(17p), del(11q)]); (2) intermediate‐risk (either unmutated IGHV or adverse FISH cytogenetics) and (3) high‐risk (unmutated IGHV + adverse FISH cytogenetics). In 524 unselected subjects with CLL, the 10‐year overall survival was 82% (95% CI 76%‐88%), 52% (45%‐62%), and 27% (17%‐42%) for the low‐, intermediate‐, and high‐risk groups, respectively. Patients with low‐risk comprised around 50% of the series and had a life expectancy comparable to the general population. The prognostic model was fully validated in two independent cohorts, including 417 patients representative of general CLL population and 337 patients with Binet stage A CLL. The model had a similar discriminatory value as the CLL‐IPI. Moreover, it applied to all patients with CLL independently of age, and separated patients with different risk within Rai or Binet clinical stages. The biomarkers‐only CLL prognostic system presented here simplifies the CLL‐IPI and could be useful in daily practice and to stratify patients in clinical trials.
Understanding influences of culture and history on mtDNA variation and population structure in three populations from Assam, Northeast India
Authors: Rej Peter H. , Deka Ranjan , Norton Heather L.
Published: January 2017

Objectives

Positioned at the nexus of India, China, and Southeast Asia, Northeast India is presumed to have served as a channel for land‐based human migration since the Upper Pleistocene. Assam is the largest state in the Northeast. We characterized the genetic background of three populations and examined the ways in which their population histories and cultural practices have influenced levels of intrasample and intersample variation.

Methods

We examined sequence data from the mtDNA hypervariable control region and selected diagnostic mutations from the coding region in 128 individuals from three ethnic groups currently living in Assam: two Scheduled tribes (Sonowal Kachari and Rabha), and the non‐Scheduled Tai Ahom.

Results

The populations of Assam sampled here express mtDNA lineages indicative of South Asian, Southeast Asian, and East Asian ancestry. We discovered two completely novel haplogroups in Assam that accounted for 6.2% of the lineages in our sample. We also identified a new subhaplogroup of M9a that is prevalent in the Sonowal Kachari of Assam (19.1%), but not present in neighboring Arunachal Pradesh, indicating substantial regional population structuring. Employing a large comparative dataset into a series of multidimensional scaling (MDS) analyses, we saw the Rabha cluster with populations sampled from Yunnan Province, indicating that the historical matrilineality of the Rabha has maintained lineages from Southern China.

Conclusion

Assam has undergone multiple colonization events in the time since the initial peopling event, with populations from Southern China and Southeast Asia having the greatest influence on maternal lineages in the region.
Selective Carbonyl−C(sp3) Bond Cleavage To Construct Ynamides, Ynoates, and Ynones by Photoredox Catalysis
Authors: Jia Kunfang , Pan Yue , Chen Yiyun
Published: January 2017

Carbon–carbon bond cleavage/functionalization is synthetically valuable, and selective carbonyl−C(sp3) bond cleavage/alkynylation presents a new perspective in constructing ynamides, ynoates, and ynones. Reported here is the first alkoxyl‐radical‐enabled carbonyl−C(sp3) bond cleavage/alkynylation reaction by photoredox catalysis. The use of novel cyclic iodine(III) reagents are essential for β‐carbonyl alkoxyl radical generation from β‐carbonyl alcohols, including alcohols with high redox potential (
>2.2 V vs. SCE in MeCN). β‐Amide, β‐ester, and β‐ketone alcohols yield ynamides, ynoates, and ynones, respectively, for the first time, with excellent regio‐ and chemoselectivity under mild reaction conditions.
Growth of Stable Surface Oxides on Pt(111) at Near‐Ambient Pressures
Authors: Fantauzzi Donato , Krick Calderón Sandra , Mueller Jonathan E. , Grabau Mathias , Papp Christian , Steinrück Hans‐Peter , Senftle Thomas P. , van Duin Adri C. T. , Jacob Timo
Published: January 2017

Detailed knowledge of the structure and degree of oxidation of platinum surfaces under operando conditions is essential for understanding catalytic performance. However, experimental investigations of platinum surface oxides have been hampered by technical limitations, preventing in situ investigations at relevant pressures. As a result, the time‐dependent evolution of oxide formation has only received superficial treatment. In addition, the amorphous structures of many surface oxides have hindered realistic theoretical studies. Using near‐ambient pressure X‐ray photoelectron spectroscopy (NAP‐XPS) we show that a time scale of hours (t≥4 h) is required for the formation of platinum surface oxides. These experimental observations are consistent with ReaxFF grand canonical Monte Carlo (ReaxFF‐GCMC) calculations, predicting the structures and coverages of stable, amorphous surface oxides at temperatures between 430–680 K and an O2 partial pressure of 1 mbar.
Sequence‐Controlled Polymers with Furan‐Protected Maleimide as a Latent Monomer
Authors: Ji Yuxuan , Zhang Liuqiao , Gu Xue , Zhang Wei , Zhou Nianchen , Zhang Zhengbiao , Zhu Xiulin
Published: January 2017

Herein, a novel methodology for preparing sequence‐controlled polymers is illustrated by using a latent monomer, furan protected maleimide (FMI). At 110 °C, FMI is deprotected by retro Diels–Alder (rDA) reaction, and the released MI is immediately involved in the cross‐polymerization with styrene (St) to deliver heterosegments. At 40 °C the rDA reaction does not proceed, therefore homo‐poly(styrene) segments are produced. By implementing programmable temperature changes during polymerization of St and FMI, “living” polymers with tailored a sequence are created. A ternary copolymerization produces complex sequences as designed. Alkynyl‐functionalized FMI, used as a latent monomer, leads to the desirable placement of functional groups along the polymer chain. This latent‐monomer‐based strategy opens a new avenue for fabricating sequence‐controlled polymers.
Supramolecular Graft Copolymerization of a Polyester by Guest‐Selective Encapsulation of a Self‐Assembled Capsule
Authors: Tsunoda Yuta , Takatsuka Mei , Sekiya Ryo , Haino Takeharu
Published: January 2017

Repeating guest units of polyesters poly‐(R)‐2 were selectively encapsulated by capsule 1(BF4)4 to produce supramolecular graft polymers. The encapsulation of the guest units was confirmed by 1H NMR spectroscopy. The graft polymer structures were confirmed by the increase in the hydrodynamic radii and the solution viscosities of the polyesters upon complexation of the capsule. After the capsule was formed, atomic force microscopy showed extension of the polyester chains. The introduction of the graft chains onto poly‐(R)‐2 resulted in the main chain of the polymer having an M‐helical morphology. The complexation of copolymers poly‐[(R)‐2‐co‐(S)‐2] by the capsule gave rise to the unique chiral amplification known as the majority‐rules effect.
Gelatin and pregelatinized starch orally disintegrating films: Properties and stability of vitamin C
Authors: dos Santos Garcia Vitor Augusto , Gonçalves Borges Josiane , Mazalli Mônica Roberta , Lapa‐Guimarães Judite das Graças , Vanin Fernanda Maria , de Carvalho Rosemary Aparecida
Published: January 2017

The administration of active compounds by the oral mucosa is an efficient method for the delivery of drugs and nutrients. This work aimed to develop and characterize orally disintegrating films (ODFs) based on starch and gelatin as carriers of vitamin C. The ODFs were produced using a casting technique by varying the concentrations of starch and gelatin (0, 20, 40, 60, 80, and 100 g of starch/100 g of polymer) and were characterized in relation to contact angle, opacity, surface pH, infrared spectroscopy, mechanical properties, morphology, and disintegration time (in vitro and in vivo). Additionally, the stability of vitamin C in the ODFs was evaluated by the incorporation of the dry extract of acerola (4 g/100 g of filmogenic solution). Generally, the ODFs presented hydrophilic characteristics with a neutral surface pH near the mouth, and films with higher starch concentrations showed greater rigidity. In vitro and in vivo tests indicated that ODFs may be classified as rapidly disintegrating. The ODFs produced with higher concentrations of starch showed a higher stability of the active compound, in addition to a shorter disintegration time. Starch‐ and gelatin‐based ODFs can be considered a new system for administering active ingredients via the oral mucosa. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44841.
Education, parenting and family: The social geographies of family learning
Authors: Wainwright Emma , Marandet Elodie
Published: January 2017

This paper explores the relationship between education, parenting and family through the prism and particularities of family learning. Family learning is an example of an educational initiative, primarily aimed at parents and linked to wider policy concerns, which can be explored through a mapping of its social geographies; family learning is played out across and productive of different sites, spaces and identities. Based on qualitative research undertaken in West London, this paper draws on individual and group interviews with mothers participating in family learning classes and interviews with family learning providers. The key argument we extend is that focusing on the social geographies of family learning ‐ of home, school, work, community and nation ‐ allows us to see how educational initiatives extend the state's reach in family life, producing particular normative versions of family and ‘good’ parenting operating at a range of interconnecting scales. Education remains a cornerstone of family policy in the UK and detailed analyses of specific initiatives at the point of implementation – how they are practiced and received – is vital for better understanding their diverse and varied effects in contemporary society.
Clinical trials in surgical infection
Authors: Marshall J C
Published: January 2017

Change is needed
Randomized clinical trial of 24 versus 72 h antimicrobial prophylaxis in patients undergoing open total gastrectomy for gastric cancer
Authors: Takagane A , Mohri Y , Konishi T , Fukushima R , Noie T , Sueyoshi S , Omura K , Ono S , Kusunoki M , Mochizuki H , Sumiyama Y
Published: January 2017

Background

Open total gastrectomy carries a high risk of surgical-site infection (SSI). This study evaluated the non-inferiority of antimicrobial prophylaxis for 24 compared with 72 h after open total gastrectomy.

Methods

An open-label, randomized, non-inferiority study was conducted at 57 institutions in Japan. Eligible patients were those who underwent open total gastrectomy for gastric cancer. Patients were assigned randomly to continued use of β-lactamase inhibitor for either 24 or 72 h after surgery. The primary endpoint was the incidence of SSI, with non-inferiority based on a margin of 9 percentage points and a 90 per cent c.i. The secondary endpoint was the incidence of remote infection.

Results

A total of 464 patients (24 h prophylaxis, 228; 72 h prophylaxis, 236) were analysed. SSI occurred in 20 patients (8·8 per cent) in the 24-h prophylaxis group and 26 (11·0 per cent) in the 72-h group (absolute difference −2·2 (90 per cent c.i. −6·8 to 2·4) per cent; P < 0·001 for non-inferiority). However, the incidence of remote infection was significantly higher in the 24-h prophylaxis group.

Conclusion

Antimicrobial prophylaxis for 24 h after total gastrectomy is not inferior to 72 h prophylaxis for prevention of SSI. Shortened antimicrobial prophylaxis might increase the incidence of remote infection. Registration number: UMIN000001062 (http://www.umin.ac.jp).
Effect of preoperative biliary drainage on bacterial flora in bile of patients with periampullary cancer
Authors: Scheufele F , Aichinger L , Jäger C , Demir I E , Schorn S , Sargut M , Erkan M , Kleeff J , Friess H , Ceyhan G O
Published: January 2017

Background

Patients with obstructive jaundice due to periampullary tumours may undergo preoperative biliary drainage (PBD). The effect of PBD on the microbiome of the biliary system and on postoperative outcome remains unclear.

Methods

A single-centre retrospective study of patients with obstructive jaundice due to periampullary cancer, treated between July 2007 and July 2015, was undertaken. Intraoperative bile samples were obtained for microbiological analysis after transection of the common bile duct. Postoperative complications were registered.

Results

Of 290 patients treated, intraoperative bile samples were present for 172 patients (59·3 per cent) who had PBD and 118 (40·7 per cent) who did not. Contamination of bile was increased significantly in patients who underwent stenting (97·1 per cent versus 18·6 per cent in those without stenting; P < 0·001). PBD resulted in a shift in the biliary microbiome from Escherichia coli in non-stented patients (45 per cent versus 19·2 per cent in stented patients; P = 0·009) towards increased contamination with Enterococcus faecalis (9 versus 37·7 per cent respectively; P = 0·008) and Enterobacter cloacae (0 versus 20·4 per cent; P = 0·033). This shift was associated with a high incidence of bacterial resistance against ampicillin–sulbactam (63·6 per cent versus 18 per cent in patients with no PBD; P < 0·001), piperacillin–tazobactam (30·1 versus 0 per cent respectively; P = 0·003), ciprofloxacin (28·5 versus 5 per cent; P = 0·047) and imipenem (26·6 versus 0 per cent; P = 0·011). The rate of wound infection was higher in patients with a positive bile culture (21·0 per cent versus 6 per cent in patients with sterile bile; P = 0·002). Regression analysis revealed the presence of Enterococcus faecium (odds ratio 2·83, 95 per cent c.i. 1·17 to 6·84; P = 0·021) and Citrobacter species (odds ratio 5·09, 1·65 to 15·71; P = 0·005) as independent risk factors for postoperative wound infection.

Conclusion

There are fundamental differences in the biliary microbiome of patients with periampullary cancer who undergo PBD and those who do not. PBD induces a shift of the biliary microbiome towards a more aggressive and resistant spectrum, which requires a differentiated perioperative antibiotic treatment strategy.
Development of an Arsenobetaine Standard Solution with Metrological Traceability to the SI by an Arsenic‐specific Mass Balance Method
Authors: Ko Kyung‐Moon , Kim In Jung , Go Cheongah , Yim Yong‐Hyeon , Lim Yongran , Kim Tae Kyu , Yoon Ilsun , Hwang Euijin , Lee Kyoung‐Seok
Published: January 2017

An arsenobetaine (AsB) standard solution with metrological traceability to the International System of Units was developed as a calibration standard for the quantitative analysis of AsB. An arsenic‐specific mass balance method was established for the certification of the AsB standard solution. The accurate mass fraction of total arsenic in the solution was determined by instrumental neutron activation analysis with direct comparator method. Arsenic‐containing impurities were evaluated by arsenic speciation analysis using liquid chromatography‐inductively coupled plasma mass spectrometry (LC‐ICP‐MS). Two LC separation methods were adopted for comprehensive coverage of the impurities, which include the reversed‐phase LC with ion‐pairing and the cation exchange chromatography. The only arsenic‐containing impurity observed by LC‐ICP‐MS was trace level of trimethylarsine oxide. The mass fraction of arsenic in the form of AsB was obtained by subtracting the arsenic mass fractions of the impurities from the total arsenic in the standard solution. The between‐bottle inhomogeneity of AsB content in the standard solution was less than 0.7%, which was estimated from the relative standard deviation of the measurement results obtained from 10 representative sample bottles from a batch. The certified value of AsB and its expanded uncertainty as arsenic mass fraction were assigned to be (51.28 ± 1.17) mg/kg (k = 2 approximately at 95% level of confidence).
MonitTDPA: A tool for monitoring the tracing of dynamic programming algorithms
Authors: Bahig Hazem M. , Khedr Ahmed Y.
Published: January 2017

Algorithms are important procedures that are found in every aspect in our life. Large numbers of these algorithms cannot be accurately understood unless they are presented differently, especially if they are taught to students. A complete visualization system is created to teach dynamic programming algorithms. Through visualization, a student is able to trace the algorithm step‐by‐step, similar to the debugger, but in a simplified way. In addition, the system can handle errors during the execution of the algorithm. Moreover, the system guides and helps the students during the tracing and stores all of the information about the errors during the tracing. The students obtain the feedback of the tracing from a report generated by the system. The teacher benefits from the generated report through the enhancement of the teaching methods that focus on the misunderstood steps. Additionally, the system allows the user to see how a certain algorithm can be monitored by displaying the source code. The developed system is evaluated using different methods to prove the effectiveness of the system in teaching and learning.© 2017 Wiley Periodicals, Inc. Comput Appl Eng Educ 25:179–187, 2017; View this article online at wileyonlinelibrary.com/journal/cae; DOI 10.1002/cae21781.
Chemical Composition and Behavioral Effects of Five Plant Essential Oils on the Green Pea Aphid Acyrthosiphon pisum (Harris) (Homoptera: Aphididae)
Authors: Kasmi Abir , Hammami Majdi , Raoelison Emmanuel G. , Abderrabba Manef , Bouajila Jalloul , Ducamp Christine
Published: January 2017

Essential oils (EOs) from Schinus molle, Helichrysum gymnocephalum, Cedrelopsis grevei and Melaleuca viridiflora, four aromatic and medicinal plants, are commonly used in folk medicine. EOs were characterized by gas chromatography/mass spectrometry (GC/MS) and quantified by gas chromatography‐flame ionization detection (GC‐FID); then evaluated for their behavioral effects on adults of the green pea aphid Acyrthosiphon pisum (Harris) using a Perspex four‐armed olfactometer in order to test the compatibility of their use as phytoinsecticides to control this insect pest. Our results showed that the EOs from the leaves of S. molle, M. viridiflora and C. grevei did not change aphids’ behavior. However, S. molle fruits EO seemed to be attractive while H. gymnocephalum leaves EO exhibited repellency towards aphids at a dose of 10 μl. The major compounds in S. molle fruits EO were 6‐epi‐shyobunol (16.22%) and d‐limonene (15.35%). While, in H. gymnocephalum leaves EO, 1,8‐cineole was the main compound (47.4%). The difference in aphids’ responses to these two EOs could be attributed to the differences in their compositions. Our findings suggest that these two EOs have potential applications for the integrated pest management of A. pisum (Harris).
A Triflamide‐Tethered N‐Heterocyclic Carbene–Rhodium(I) Catalyst for Hydroalkoxylation Reactions: Ligand‐Promoted Nucleophilic Activation of Alcohols
Authors: Sarbajna Abir , Pandey Pragati , Rahaman S. M. Wahidur , Singh Kuldeep , Tyagi Akshi , Dixneuf Pierre H. , Bera Jitendra. K.
Published: January 2017

A triflamide‐tethered N‐heterocyclic carbene (NHC)‐bound RhI dicarbonyl catalyst was highly effective for both intermolecular hydroalkoxylation and intramolecular heteroannulation reactions. The involvement of both the amido nitrogen and triflato oxygen atoms of the triflamide functionality for alcohol activation and 1,2‐hydrogen shift, respectively, was proposed.
New Carbon Monoliths for Supercapacitor Electrodes. Looking at the Double Layer
Authors: Moreno‐Fernandez Gelines , Kunowsky Mirko , Lillo‐Ródenas Maria Ángeles , Ibañez Joaquin , Rojo Jose M.
Published: January 2017

Carbon monoliths are prepared by combining two carbon phases. A major phase is activated anthracite, which provides microporosity and a large surface area. The other phase is a carbonized polymer that provides self‐consistency and contributes to densifying the monolith. Different degrees of anthracite activation and different contents of the two phases are investigated. These all‐carbon monoliths have surface areas up to 2600 m2 g−1, mechanical strengths up to 6 MPa, electrical conductivities up to 2–4 S cm−1, and densities between 0.4 and 0.7 g cm−3. In sulfuric acid electrolyte, gravimetric capacitances up to 307 F g−1 are achieved. The double‐layer capacitances due to the hydronium and bisulfate ions are separately measured, the former being approximately 25% higher than the latter. The size of the two ions electro‐adsorbed at the double layer is discussed. The pseudocapacitance associated with the hydronium ion is 10–25% of the total capacitance of this ion. All of the carbon monoliths show high capacitance retention with current density; the retention of the double‐layer capacitance is similar for the two types of ions and higher than the retention of the pseudocapacitance associated with the hydronium ion.
Optically Active Phenylethene Dimers Based on Planar Chiral Tetrasubstituted [2.2]Paracyclophane
Authors: Gon Masayuki , Morisaki Yasuhiro , Chujo Yoshiki
Published: January 2017

Optically active phenylethene dimers based on a planar chiral 4,7,12,15‐tetrasubstituted [2.2]paracyclophane were synthesized. We succeeded in controlling the molecular motion by binding luminophores in close proximity with the [2.2]paracyclophane scaffold. For example, aggregation‐induced emission (AIE)‐active luminophores were converted to show intense photoluminescence (PL) even in a diluted solution at room temperature and the resulting compound worked as a single‐molecule thermoresponsible material around room temperature. Because of the AIE‐active unit, the molecular motion could be easily activated by heating, leading to variable and reversible PL intensity. Furthermore, the π‐conjugated systems with the planar chirality of 4,7,12,15‐tetrasubstituted [2.2]paracyclophane provided excellent characteristics on circular dichroism (CD) and circularly polarized luminescence (CPL). The obtained dimers showed high CPL performances both in a diluted solution and in an aggregation state. We succeeded in proving that simple molecular designs composed of only carbon and hydrogen atoms could create versatile optical functionalities.
Adverse Effects of Excess Residual PbI2 on Photovoltaic Performance, Charge Separation, and Trap‐State Properties in Mesoporous Structured Perovskite Solar Cells
Authors: Wang Hao‐Yi , Hao Ming‐Yang , Han Jun , Yu Man , Qin Yujun , Zhang Pu , Guo Zhi‐Xin , Ai Xi‐Cheng , Zhang Jian‐Ping
Published: January 2017

Organic–inorganic halide perovskite solar cells have rapidly come to prominence in the photovoltaic field. In this context, CH3NH3PbI3, as the most widely adopted active layer, has been attracting great attention. Generally, in a CH3NH3PbI3 layer, unreacted PbI2 inevitably coexists with the perovskite crystals, especially following a two‐step fabrication process. There appears to be a consensus that an appropriate amount of unreacted PbI2 is beneficial to the overall photovoltaic performance of a device, the only disadvantageous aspect of excess residual PbI2 being viewed as its insulating nature. However, the further development of such perovskite‐based devices requires a deeper understanding of the role of residual PbI2. In this work, PbI2‐enriched and PbI2‐controlled perovskite films, as two extreme cases, have been prepared by modulating the crystallinity of a pre‐deposited PbI2 film. The effects of excess residual PbI2 have been elucidated on the basis of spectroscopic and optoelectronic studies. The initial charge separation, the trap‐state density, and the trap‐state distribution have all been found to be adversely affected in PbI2‐enriched devices, to the detriment of photovoltaic performance. This leads to a biphasic recombination process and accelerates the charge carrier recombination dynamics.
Supramolecular Polymerization of Supermacrocycles: Effect of Molecular Conformations on Kinetics and Morphology
Authors: Yamauchi Mitsuaki , Adhikari Bimalendu , Prabhu Deepak D. , Lin Xu , Karatsu Takashi , Ohba Tomonori , Shimizu Nobutaka , Takagi Hideaki , Haruki Rie , Adachi Shin‐ichi , Kajitani Takashi , Fukushima Takanori , Yagai Shiki
Published: January 2017

Intricately designed π‐conjugated molecules containing interactive groups can be used to generate supramolecular polymers with outstanding structural and functional properties. To construct such supramolecular polymers, the non‐covalent synthesis of supermacrocyclic monomers from relatively simple molecules represents an attractive strategy, although this has been rarely exploited. Here, we report the supramolecular polymerization of two barbiturate‐naphthalene derivatives that circularly hexamerize by hydrogen bonding. The two molecules contain an aliphatic “wedge” unit with either an ether or ester linkage. This subtle difference is amplified into distinct features both in terms of the morphology of the supramolecular polymers and the polymerization process. The degrees of conformational freedom of the wedge unit determine the stacking of the supermacrocycles, as is evident from 2D X‐ray diffraction analyses on the aligned fibers. The differences in stacking impart the supramolecular polymer fibers with different morphological features (cylindrical or helical), which are reflected in the properties of concentrated solutions (suspension or gel). The degrees of conformational freedom of the wedge unit also affect the polymerization kinetics, in which the more flexible ether linkage induces pathway complexity by the formation of off‐pathway aggregates.
Comparative study of magnesia‐supported highly‐dispersed CuO solids prepared by different methods in CO oxidation
Authors: Kosmambetova Gulnara R. , Kalchuk Natalia S. , Didenko Olga Z. , Strizhak Peter E.
Published: January 2017

Magnesia‐supported highly‐dispersed CuO solids were prepared by impregnation and mechanical mixing of CuO nanopowders with MgO. Additionally, ultrasound and mechanochemical treatment of CuO nanopowders mixed with MgO was performed. TEM and XRD studies indicate that the size of the CuO nanoparticles in solids depends on the method of preparation. Catalytic tests of these solids in the CO oxidation show that varying the method of catalyst preparation changes the temperature of the 100 % conversion CO by more than 130 °C. Fabrication of the CuO‐MgO catalysts via an easy mixing process using CuO nanopowder and cubic MgO gives the most active catalyst. Mechanochemical and/or ultrasound treatments lead to catalyst deactivation. Our results show that method of the catalyst preparation influences the catalyst performance mainly through varying the CuO nanoparticle size and CuO‐support interaction.
Intercalation into a Prussian Blue Derivative from Solutions Containing Two Species of Cations
Authors: Erinmwingbovo Collins , Palagonia Maria Sofia , Brogioli Doriano , La Mantia Fabio
Published: January 2017

Reversible mixed‐ion intercalation in nonselective host structures has promising applications in desalination, mixed‐ion batteries, wastewater treatment, and lithium recovery through electrochemical ion pumping. One class of host compound that possesses many of the requirements needed for such applications (cost effectiveness, fast ion kinetics, and stability in an aqueous medium) includes the Prussian blue derivatives. Herein, the fundamental process of intercalation of multiple cations is studied at the thermodynamic level by means of galvanostatic cycling. Nickel hexacyanoferrate is focused upon because of its stability and low potential for electrochemical process relative to other hexacyanoferrates. Various cations can be intercalated; large cations (K+ and NH4+) are intercalated at higher potentials than those of smaller cations (Na+). When mixtures of cations are present in solution, the potential profile is not qualitatively altered with respect to single‐salt solutions, but the potential of (de‐)intercalation is shifted; a simple thermodynamic model is introducted that is able to predict the potential and distribution at which intercalation takes place.
Magnetically Recoverable Pd/Fe3O4 Core–Shell Nanowire Clusters with Increased Hydrogenation Activity
Authors: Watt John , Kotula Paul G. , Huber Dale L.
Published: January 2017

Core–shell nanostructures are promising candidates for the next generation of catalysts due to synergistic effects which can arise from having two active species in close contact, leading to increased activity. Likewise, catalysts displaying added functionality, such as a magnetic response, can have increased scientific and industrial potential. Here, Pd/Fe3O4 core–shell nanowire clusters are synthesized and applied as hydrogenation catalysts for an industrially important hydrogenation reaction: the conversion of acetophenone to 1‐phenylethanol. During synthesis, the palladium nanowires self‐assemble into clusters which act as a high‐surface‐area framework for the growth of a magnetic iron oxide shell. This material demonstrates excellent catalytic activity due to the presence of palladium while the strong magnetic properties provided by the iron oxide shell enable facile catalyst recovery.
Vectorization and Intracellular Distribution of a Two‐Photon‐Absorbing, Near‐Infrared‐Emitting π‐Extended Boranil Dye
Authors: Frath Denis , Didier Pascal , Mély Yves , Massue Julien , Ulrich Gilles
Published: January 2017

A π‐extended boranil (PEB) dye has been synthesized and its photophysical properties have been recorded in a range of solvents. The dye exhibits an intense solvatochromic fluorescence emission covering the entire visible spectrum and the near infra‐red (NIR) region (from λ=534 to 764 nm) with quantum yields up to 69 %. Embedment of the PEB dye in the amphiphilic block copolymer Cremophor EL® leads to a strong emission (λem=617 nm, Φ=0.33) in PBS buffer. Moreover, two‐photon absorption (TPA) spectroscopy evidenced a large two‐photon (2P) cross section (420 GM), enabling the use of the PEB dye in 2P‐excitation fluorescence microscopy. The cellular uptake and distribution of PEB in HeLa cells was monitored using fluorescence lifetime imaging microscopy (FLIM) and real‐time widefield imaging. It was found that the emission of the dye is strongly influenced by the local environment and that the dye is preferentially internalized in acidic vesicles.
Generation and correlation of orthogonal complementary pairs of sequences of lengths 2N10M26P based on an improved multilevel complementary sequences approach
Authors: Hadad M. N. , Donato P. G. , Funes M. A. , Carrica D. O.
Published: January 2017

Binary complementary pairs of sequences of lengths 2N10M26P posses some interesting properties for their application in signal detection in noisy channels. Nonetheless, they have not been broadly used because of their greater processing requirements as compared with binary complementary sequences with L = 2N. The present work introduces a new approach for generation and correlation of binary complementary pairs of sequences of length 2N10M26P that reduces the number of required operations. The proposed algorithm allows not only to optimize the number of arithmetic operations but also to correlate two orthogonal complementary pairs simultaneously with the use of a single architecture. Due to the fact that multilevel complementary sequences algorithms are used to generate and correlate binary complementary sequences of length 2N10M26P, the aforementioned algorithms are also improved. The proposal is theoretically proved and its arithmetic efficiency is assessed by comparing the number of operations with that of previously published architectures. Copyright © 2017 John Wiley & Sons, Ltd.