bluuebunny/crossref_metadata_2025 huggingface dataset:
Numerical Simulation of Characteristics of Spray Flow Field on the Conical Surface
Authors: Chen Shiming , GuichunYang  , Zhou Shuang , Chen Wenzhuo , Guan Jinfa , Chen Yan
Published: November 2020

Aiming at the gas-liquid two-phase flow process in the spray flow field on the conical outer surface, based on Euler-Euler method a spray film forming model is proposed. A polyhedral mesh was utilized to divide the fluid computing domain and the coupled SIMPLE algorithm was adopted to solve the model. The results of show that the spray shape on the outer surface of the cone is similar to that on the outer surface of the arc, and both are in the shape of an elliptical cone; in the area far away from the wall surface, the difference ofsurface has almost no effect on the spray cone angle. In terms of the spraying speeds of the two spraying methods within the area close to the outer surface of the cone, for the circumferential spraying, the spray normal speed is higher than that of spraying along the busbar, and the maximum tangential speed is lower. Meanwhile, both the two speeds are almost equal to that of spraying the arc surface; for spraying along the busbar, the spray normal speed is higher than that of the arc outer surface, and the maximum tangential speed is lower.
A Prediction Model of Online Car-Hailing Demand Based on K-means and SVR
Authors: Chen Bang , Zhou Shenghan , Liu Houxiang , Ji Xinpeng , Zhang Yue , Chang Wenbing , Xiao Yiyong , Pan Xing
Published: November 2020

The paper proposed a prediction model of online car-hailing demand based on K-means and support vector regression (SVR) methods. In the past few years, online car-hailing market demand has grown rapidly, and prediction of rapid demand growth has become a hot topic. This study takes the initial longitude and latitude of online car-hailing orders as the eigenvalues for K-means clustering. The clustering results are taken as the result of area division. The number and size of potential demand areas could be determined automatically. This method of area division solves the shortcomings of traditional artificial meshing division and existing administrative division methods. The model takes a small-sample data set as the application object and uses the SVR method for data regression. Finally, we conduct an empirical study on Didi’s real data set in the core area of Chengdu City, China. The final experimental results suggest that the area division method based on K-means is reasonable and that the demand prediction model based on K-means and SVR is effective.
Research on Heat Conduction Model of Special Equipment Based on Difference Equation
Authors: Tan Jintao , Xia Jie , Gu Musong , Li Li
Published: November 2020

Special equipment plays an important role in the life safety of special operators. With the development of economy and society, the performance requirements of special equipment are higher and higher. In this paper, the fire-proof clothing in special equipment is taken as an example to study the internal temperature change of the fire-proof clothing in high temperature environment and improve the design of the fire-proof clothing. Through Newton’s law of cooling and Fourier’s law, combined with the relevant physical parameters, we establish the heat conduction model of the fire suit, discretize the differential equation in the model, use the chasing and driving method to solve the tridiagonal matrix after discretization, and transform the unknown parameters (heat extraction coefficient) in the model into a two-parameter optimization problem, combining with the classical optimization algorithm—The genetic algorithm is solved. Experiments show that our model can better solve this kind of problems, and the fitting accuracy is increased by 10%. Through the fitting image of the experimental results, we can see the improvement of the accuracy directly. Through the improvement, our model can improve the fitting accuracy, which is of great significance for the design and research of special equipment Fire clothing, and also has certain reference value for solving similar problems.
Study on High Temperature Wear-Resistant Coatings on Surface of Special Steel by Orthogonal Test
Authors: Xu Jingyu , Yuan Zhihua , Zhang Aili , Zhao Junqiang , Zhang Shengnan
Published: November 2020

In order to improve the friction and wear performance of steel under severe service conditions such as high temperature, epoxy resin E-51 resin is used as the base material, graphite, MoS2 and other high temperature wear-resistant materials are used as pigments to prepare a kind of oil-coated high temperature resistant paint. The entropy weight method is used to comprehensively evaluate high temperature wear, thermal weight loss rate, and corrosion current density. The results show that the coating optimized by the entropy weight method has excellent performance. Among them, the high temperature wear rate of the paint film is 0.83%, the thermal weight loss rate at 200 °C is 4.56%, the thermal weight loss rate at 400 °C is 27.84%, and the corrosion current density is 9.31E-9. The alkali resistance of the paint film is far greater than the national standard.
Research on the Definition of Small and Medium-sized Coastal Dry Bulk Shipping Enterprises Based on Data Mining
Authors: Wei Hongbin , Li Yunbo , Gong Jiaye , Du Wenquan
Published: November 2020

Shipping industry is an important part of the transportation industry. Small and medium-sized shipping enterprises play an important part in protecting the internal vitality of the shipping industry. However, there is no research on the definition of large and medium-sized shipping enterprises. Data mining method has become a convenient tool for mining the value of large data. This study first defines of shipping enterprises, and then discusses the definition of small and medium-sized coastal dry bulk shipping enterprises for the first time from the perspective of large data. This study is the first time to apply the cluster analysis method to research the data value of shipping enterprises, aiming to quantitatively define the scale of coastal dry bulk shipping enterprises from the perspective of large data. This research is the first time to establish a data mining model based on large data of shipping enterprises. The shipping capacity data, ship data and financial operation data are selected as data variables. With the selected data variables, data standardization, outlier processing and clustering analysis are carried out step by step. Taking the coastal dry bulk shipping enterprises as an example, the model is analysed. Through data mining, we get the main influence data variables that distinguish large and medium-sized coastal dry bulk shipping enterprises, and get the quantitative definition results of coastal dry bulk shipping enterprises. The research results serve as a basis for further analysis of dry bulk shipping enterprises, and the research method can be used as a tool for the scale classification of other shipping enterprises.
Comprehensive Economic Evaluation of Our Provinces Factor-based Analysis
Authors: Zhang Hongmin , Zhu Manman
Published: November 2020

According to the different conditions of the research objects, 10 indicators of economic representation in 2018 are selected for 31 provinces and cities in the country, and the objective and reasonable data analysis of economic indicators is carried out by using factor analysis method, and the ranking of provinces and cities in the country is obtained according to the level of their comprehensive evaluation scores. According to the score of provincial and municipal indicators, the economic situation of 31 provinces and cities in China is classified and analyzed. And put forward the feasibility suggestion to the economic imbalance of each province and city.
Diverging pond dissolved organic matter characteristics yield similar CO2 flux potentials in a disturbed High Arctic landscape
Authors: Heslop J K , Hung J K Y , Tong H , Simpson M J , Chapman F M , Roulet N , Lafrenière M J , Lamoureux S F
Published: November 2020

Climate warming and permafrost thaw have the potential to shift Arctic carbon (C) cycling dynamics so ponds, which represent over a quarter of northern circumpolar surface water area, may play a larger role in the mineralization of terrestrial C and emission of greenhouse gases (GHG). Here, we constrain how active layer detachments (ALDs) affect C cycling dynamics in High Arctic ponds (n = 19) through the examination of geochemistry, dissolved organic matter (DOM) characteristics, and dissolved GHG concentrations. Summer rainfall events were identified as the primary source of pond water over a 5 week period during the monitored thaw season. We observed two distinct geochemical and DOM composition groups in ponds surrounded by undisturbed, vegetated areas compared to ponds located within the geomorphologically-disturbed ALDs. DOM in undisturbed areas had characteristics suggesting allochthonous origin from modern vegetation. Ponds in the ALDs had lower mean dissolved organic carbon (DOC) concentrations than ponds within undisturbed landscapes, with DOM characterization suggesting greater proportions of autochthonous DOM. Observed differences in DOC concentrations and DOM composition between ponds located within the disturbed and undisturbed landscapes did not translate into significant differences in dissolved CO2 concentrations among pond types. We conclude that our observed changes in DOM composition and characteristics in High Arctic ponds may not result in substantial increases in GHG flux as a result of continued Arctic warming.
Experimental investigation on the strength of chipped rubber-based concrete
Authors: Dhiman S , Garg R , Garg R , Singla S
Published: November 2020

In this research work, the strength and microstructure of chipped rubber-based compressed concrete have been investigated. Chipped rubber has been utilized as an option over coarse aggregate. Chipped rubber at normal instance decreases the durable properties of concrete but the combination of compression testing as well as chipped rubber replacement can significantly affect the strength of the material. During the study, coarse aggregate has been replaced at 0-50% with chipped rubber. The freshly prepared concrete has been condensed in a specially designed mould and after that compression casting technique has been applied. Samples of both compressed chipped rubber as well as uncompressed chipped rubber have been prepared and then examined further for compressive strength, split tensile strength, and abrasion resistance. Microstructures of conventional concrete, compressed rubber concrete, and uncompressed rubber concrete, has also been analyzed. The results show that the concrete with replacement by 20% of chipped rubber gives the significant results for compressive strength and split tensile strength. This proposed method should be implemented by the concrete industry from an environmental point of view.
Effect of surface modification through GTAW on high-temperature performance of 4Cr5MoSiV steel
Authors: Cai Yangchuan , Cui Yan , Zhu Lisong , Geng Keping , Han Jian
Published: November 2020

In the study, the surface modification of 4Cr5MoSiV steel through gas tungsten arc welding (GTAW) was carried out. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to investigate the evolution of phases and microstructures before and after the GTAW surface modification treatment. The microhardness, tribological behavior, and high-temperature oxidation property were systematically investigated using the tests regarding microhardness, high-temperature wear, and high-temperature oxidation. GTAW remelting process generated (FCC + BCC) dual phase, which created mutual restriction between the two phases in plastic deformation. Continuous distribution of hard Cr3C2 carbides at grain boundaries could disperse local stresses. The microhardness of the GTAW remelting layer was significantly improved, and the GTAW remelting increased the V element of the free state and formed V2O5 oxide with unique lattice structure in the oxide layer. The high-temperature oxidation performance of the GTAW remelting layer was slightly deteriorated. The high-temperature oxidation duration for the high-temperature wear test was short, and the high hardness of remelting layer and the connective carbides together played the major roles, so GTAW remelting layer had excellent resistance to high-temperature wear resistance.
Interfacial reaction and mechanical properties of diffusion bonded titanium/17-4 PH stainless steel dissimilar joint using a silver interlayer
Authors: Feng Bo , Deng Yongqiang , Feng Xiaowei , Wang Juan , Zheng Kaihong
Published: November 2020

Diffusion bonding of titanium (Ti) to 17-4 PH high strength stainless steel is challenging owing to the formation of brittle Ti-Fe intermetallic compounds (IMCs) at joint interface. In the current study, it was demonstrated that such detrimental Ti-Fe IMCs can be effectively eradicated by using a silver (Ag) interlayer. The diffusion bonded Ti/Ag/17-4 PH stainless steel is characterized by Ti-Ag solid solution, TiAg, remnant Ag interlayer and Ag-(Fe, Cr, Ni) interdiffusion layer. The interfacial reaction phase TiAg exhibited no detrimental effect on bonding strength. During tensile test, ductile fracture took place in the remaining Ag interlayer of resultant joint. Bonding strength up to ∼420 MPa was obtained over bonding durations in the range of 15 ∼ 25 min. It is thus concluded that using an Ag interlayer is highly appealing in improving bonding strength of diffusion bonded Ti/17-4 PH stainless steel dissimilar joint.
Energy dissipation and power deposition of electromagnetic waves in the plasma sheath
Authors: ZHANG Jiahui , JI Xin , YANG Keyuan , SHI Lei , WANG Qingxia
Published: November 2020

Energy dissipation and power deposition of electromagnetic waves (EMW) in the reentry plasma sheath provide an opportunity to investigate ‘communication blackout’ phenomena. Based on a finite element method (FEM) simulation, we analyze variation of EMW energy dissipation and power deposition profiles dependent on the wave polarization, wave incident angle, plasma density profile and electron collision frequency. Cutoff and resonance of EMW in the plasma sheath are crucial in explaining the regulation of energy dissipation and power deposition.
Antisaccade, a predictive marker for freezing of gait in Parkinson’s disease and gait/gaze network connectivity
Authors: Gallea Cécile , Wicki Benoit , Ewenczyk Claire , Rivaud-Péchoux Sophie , Yahia-Cherif Lydia , Pouget Pierre , Vidailhet Marie , Hainque Elodie
Published: November 2020

Freezing of gait is a challenging sign of Parkinson’s disease associated with disease severity and progression and involving the mesencephalic locomotor region. No predictive factor of freezing has been reported so far. The primary objective of this study was to identify predictors of freezing occurrence at 5 years. In addition, we tested whether functional connectivity of the mesencephalic locomotor region could explain the oculomotor factors at baseline that were predictive of freezing onset. We performed a prospective study investigating markers (parkinsonian signs, cognitive status and oculomotor recordings, with a particular focus on the antisaccade latencies) of disease progression at baseline and at 5 years. We identified two groups of patients defined by the onset of freezing at 5 years of follow-up; the ‘Freezer’ group was defined by the onset of freezing in the ON medication condition during follow-up (n = 17), while the ‘non-Freezer’ group did not (n = 8). Whole brain resting-state functional MRI was recorded at baseline to determine how antisaccade latencies were associated with connectivity of the mesencephalic locomotor region networks in patients compared to 25 age-matched healthy volunteers. Results showed that, at baseline and compared to the non-Freezer group, the Freezer group had equivalent motor or cognitive signs, but increased antisaccade latencies (P = 0.008). The 5-year course of freezing of gait was correlated with worsening antisaccade latencies (P = 0.0007). Baseline antisaccade latencies was also predictive of the freezing onset (χ2 = 0.008). Resting state connectivity of mesencephalic locomotor region networks correlated with (i) antisaccade latency differently in patients and healthy volunteers at baseline; and (ii) the further increase of antisaccade latency at 5 years. We concluded that antisaccade latency is a predictive marker of the 5-year onset of freezing of gait. Our study suggests that functional networks associated with gait and gaze control are concurrently altered during the course of the disease.
Dose–response association between adult height and all-cause mortality: a systematic review and meta-analysis of cohort studies
Authors: Li Quanman , Liu Yu , Sun Xizhuo , Li Honghui , Cheng Cheng , Liu Leilei , Liu Feiyan , Zhou Qionggui , Guo Chunmei , Tian Gang , Qie Ranran , Han Minghui , Huang Shengbing , Li Linlin , Wang Bingyuan , Zhao Yang , Ren Yongcheng , Zhang Ming , Hu Dongsheng , Wu Jian , Lu Jie
Published: November 2020

Background

We conducted a systematic review and meta-analysis from published cohort studies to examine the association of adult height and all-cause mortality and to further explore the dose–response association.

Methods

PubMed, The Cochrane Library, The Ovid, CNKI, CQVIP and Wanfang databases were searched for articles published from database inception to 6 February 2018. We used the DerSimonian–Laird random-effects model to estimate the quantitative association between adult height and all-cause mortality and the restricted cubic splines to model the dose–response association.

Results

We included 15 articles, with 1 533 438 death events and 2 854 543 study participants. For each 5-cm height increase below the average, the risk of all-cause mortality was reduced by 7% [relative risk (RR) = 0.93, 95% confidence interval (CI), 0.89–0.97] for men and 5% (RR = 0.95, 95% CI, 0.90–0.99) for women. All-cause mortality had a U-shaped association with adult height, the lowest risk occurring at 174 cm for men and 158 cm for women (both Pnonlinearity < 0.001). Relative to the shortest adult height (147 cm for men and 137 cm for women), men at 174 cm had a 47% lower likelihood of all-cause mortality and women at 158 cm a 33% lower risk of all-cause mortality.

Conclusions

Our study suggests that the relation between adult height and all-cause mortality is approximately U-shaped in both men and women.
Massey Products for Graph Homology
Authors: Ward Benjamin C
Published: November 2020

This paper shows that the operad encoding modular operads is Koszul. Using this result, we construct higher composition operations on (hairy) graph homology, which characterize its rational homotopy type.
Utility of Shoelace Technique in Closure of Fasciotomy Wounds in Electric Burns
Authors: Arumugam Praveen Kumar , Muthukumar Vamseedharan , Bamal Rahul
Published: November 2020

Fasciotomy is indicated to relieve compartment syndrome caused by electric burns. Many techniques are available to close the fasciotomy wounds including vacuum-assisted closure, skin grafting, and healing by secondary intention. This study assessed the shoelace technique in fasciotomy wound closure in patients with electric burns. The study included 19 fasciotomy wounds that were treated by shoelace technique (Group ST, n = 10 fasciotomy wounds) or by skin grafting/healing by secondary intention (Group C, n = 9 fasciotomy wounds). Data were collected for wound surface area, time to intervention, time to wound closure, rate of decrease in wound surface area after application of shoelace technique and associated complications.

The mean time to intervention after fasciotomy was significantly lower in Group ST—7.6 ± 3.8 days as compared to 15.8 ± 5.3 days in Group C (P = .004). The median time to closure was also significantly lower in Group ST—7 days (range 6–10) as compared to Group C—20 days (range 12–48) (P < .001). Primary closure was achieved in 80% cases in the group ST and no complications were recorded. The shoelace technique is an economical, fast, and effective method of fasciotomy wound closure in electric burns, especially in high volume centers and resource-limited areas.
The effects of evolutionary and environmental variance on estimates of phylogenetic diversity in temperate forest plots
Authors: Xu Yong , Liu Jia-Jia , Li Hai-Ning , Liu Juan , Burgess Kevin S , Ge Xue-Jun
Published: November 2020

Aims

Phylogenetic diversity metrics can discern the relative contributions of ecological and evolutionary processes associated with the assembly of plant communities. However, the magnitude of the potential variation associated with phylogenetic methodologies, and its effect on estimates of phylogenetic diversity, remains poorly understood. Here, we assess how sources of variation associated with estimates of phylogenetic diversity can potentially affect our understanding of plant community structure for a series of temperate forest plots in China.

Methods

In total, 20 forest plots, comprising of 274 woody species and 581 herbaceous species, were surveyed and sampled along an elevational gradient of 2800 m on Taibai Mountain, China. We used multi-model inference to search for the most parsimonious relationship between estimates of phylogenetic diversity and each of four predictors (i.e. type of phylogenetic reconstruction method, phylogenetic diversity metric, woody or herbaceous growth form and elevation), and their pairwise interactions.

Important Findings

There was no significant difference in patterns of phylogenetic diversity when using synthesis-based vs. molecular-based phylogenetic methods. Results showed that elevation, the type of phylogenetic diversity metric, growth form and their interactions, accounted for >44% of the variance in our estimates of phylogenetic diversity. In general, phylogenetic diversity decreased with increasing elevation; however, the trend was weaker for herbaceous plants than for woody plants. Moreover, the three phylogenetic diversity metrics showed consistent patterns (i.e. clustered) across the elevational gradient for woody plants. For herbaceous plants, the mean pairwise distance showed a random distribution over the gradient. These results suggest that a better understanding of temperate forest community structure can be obtained when estimates of phylogenetic diversity include methodological and environmental sources of variation.
Deceit, Deservingness, and Destitution: Able-Bodied Widows and the New Poor Law
Authors: Muller Nadine
Published: November 2020

The death of a husband had adverse economic effects for the majority of Victorian women, but for working-class mothers the threat of destitution was an almost inevitable feature of widowhood. Widows, with some restrictions, were entitled to outdoor relief under the Poor Law Amendment Act (1834), and they comprised the largest group of adult paupers outside of the workhouse well into the early twentieth century, outnumbered only and always by their children. Able-bodied widows therefore presented crucial opportunities for poor-law officials in the quest to minimize outdoor relief and make significant reductions in welfare spending. Focusing particularly on the 1830s, 1840s, and 1870s (the first decade of the so-called ‘crusade’ against out-relief), this article examines the competing discourses of deservingness and deception that dominated the representations and treatment of able-bodied widows in poor law legislation, orders, reports, and parliamentary debates. An uneasy combination of sympathy and suspicion shaped officials’ treatment of these women, rendering them ambiguous figures in the dominant dichotomy of the deserving and undeserving poor, potential drains on the economic prosperity of the state, threats to the nuclear family, and, by extension, a danger to the nation’s moral core. These discourses, I suggest, reflect a wider ideological unease with, and attempts to mitigate and police, the widow’s exceptional social status in Victorian Britain as a woman with sexual experience, potential economic independence, and yet no male guardian.
Open scholarship in Australia: A review of needs, barriers, and opportunities
Authors: Arthur Paul Longley , Hearn Lydia , Montgomery Lucy , Craig Hugh , Arbuckle Alyssa , Siemens Ray
Published: November 2020

Open scholarship encompasses open access, open data, open source software, open educational resources, and all other forms of openness in the scholarly and research environment, using digital or computational techniques, or both. It can change how knowledge is created, preserved, and shared, and can better connect academics with communities they serve. Yet, the movement toward open scholarship has encountered significant challenges. This article begins by examining the history of open scholarship in Australia. It then reviews the literature to examine key barriers hampering uptake of open scholarship, with emphasis on the humanities. This involves a review of global, institutional, systemic, and financial obstacles, followed by a synthesis of how these barriers are influenced at diverse stakeholder levels: policymakers and peak bodies, publishers, senior university administrators, researchers, librarians, and platform providers. The review illustrates how universities are increasingly hard-pressed to sustain access to publicly funded research as journal, monograph, and open scholarship costs continue to rise. Those in academia voice concerns about the lack of appropriate open scholarship infrastructure and recognition for the adoption of open practices. Limited access to credible research has led, in some cases, to public misunderstanding about legitimacy in online sources. This article, therefore, represents an urgent call for more empirical research around ‘missed opportunities’ to promote open scholarship. Only by better understanding barriers and needs across the university landscape can we address current challenges to open scholarship so research can be presented in usable and understandable ways, with data made more freely available for reuse by the broader public.
An Analysis of Airway Interventions in the Setting of Smoke Inhalation Injury on the Battlefield
Authors: Schauer Steven G , Naylor Jason F , Dion Gregory , April Michael D , Chung Kevin K , Convertino Victor A
Published: November 2020

Introduction

The Committee on Tactical Combat Casualty Care and Capabilities Development and Integration Directorate cite airway burn injuries as an indication for prehospital cricothyrotomy. We sought to build on previously published data by describing for the first time the incidence of prehospital airway interventions in combat casualties who received airway management in the setting of inhalational injuries.15,26 We hypothesized that (1) airway interventions in combat casualties who suffered inhalational injury would have a higher mortality rate than those without airway intervention and (2) prehospital cricothyrotomy was used with greater incidence than endotracheal intubation.

Materials and Methods

Using a previously described Department of Defense Trauma Registry dataset from January 2007 to August 2016, unique casualties with documented inhalational injury were identified.

Results

Our predefined search codes captured 28,222 (72.8% of all encounters in the registry) of those subjects. A total of 347 (1.2%) casualties had a documented inhalational injury, 27 (7.8%) of those with at least 1 prehospital airway intervention inhalational injuries (0.09% of our dataset [n = 28,222]). Within the subset of patients with an inhalation injury, 23 underwent intubation, 2 underwent cricothyrotomy, 3 had placement of an airway adjunct not otherwise specifically listed, and 1 casualty had both a cricothyrotomy and intubation documented. No casualties had a supraglottic, nasopharyngeal, or oropharyngeal airway listed. Contrary to our hypotheses, of those with an airway intervention, 74.0% survived to hospital discharge. In multivariable regression models, when adjusting for confounders, there was no difference in survival to discharge in those with an airway intervention compared to those without.

Conclusions

Casualties undergoing airway intervention for inhalation injuries had similar survival adjusting for injury severity, supporting its role when indicated. Without case-specific data on airway status and interventions, it is challenging to determine if the low rate of cricothyrotomy in this population was a result of rapid transport to a more advanced provider capable of performing intubation or cricothyrotomy may not be meeting the needs of the medics.
Orbital and physical parameters of eclipsing binaries from the ASAS catalogue – XI. CHIRON investigation of long-period binaries
Authors: Ratajczak M , Pawłaszek R K , Hełminiak K G , Konacki M , Sybilski P , Kozłowski S K , Litwicki M , Smith A M S , Mikołajczyk P , Anderson D R , Hellier C
Published: November 2020

We present the results of a spectroscopic campaign on eclipsing binaries with long orbital period (P = 20–75 d) carried out with the CHIRON spectrograph. Physical and orbital solutions for seven systems were derived from the V band, and I band ASAS, WASP, and TESS photometry, while radial velocities were calculated from high-quality optical spectra using a two-dimensional cross-correlation technique. The atmospheric parameters of the stars have been determined from the separated spectra. Most of our targets are composed of evolved stars (subgiants or red giants) but two systems show components in different phases of evolution and one possible merger. For four binaries, the masses and radii of the components were obtained with precision better than $3{{\ \rm per\ cent}}$. These objects provide very valuable information on stellar evolution.
Disappearance of the Fe K α emission line in ultracompact X-ray binaries 4U 1543−624 and Swift J1756.9−2508
Authors: Koliopanos Filippos , Vasilopoulos Georgios , Guillot Sebastien , Webb Natalie
Published: November 2020

We investigate the long-term variability of the iron K α line in the spectra of two ultracompact X-ray sources (UCXBs) with C/O-rich donors. We revisit archival observations from five different X-ray telescopes, over an ∼20-yr period. Adopting physically motivated models for the spectral continuum, we probe the long-term evolution of the source emission in a self-consistent manner enabling physical interpretation of potential variability of the primary X-ray continuum emission and/or any emission lines from reflection off the accretion disc. We find that the spectral shape and flux of the source emission (for both objects) has remained almost constant throughout all the observations, displaying only minor variability in some spectral parameters and the source flux (largest variation is an ∼25 per cent drop in the flux of Swift J1756.9−2508). We note a striking variability of the Fe K α line that fluctuates from a notable equivalent width of ∼66–100 eV in 4U 1543−624 and ∼170 eV in Swift J1756.9−2508 , to non-detections with upper limits of 2–8 eV. We argue that the disappearance of the iron line is due to the screening of the Fe K α line by the overabundant oxygen in the C/O-rich UCXBs. This effect is cancelled when oxygen becomes fully ionized in the inner disc region, resulting in the variability of the Fe K α line in an otherwise unaltered spectral shape. This finding supports earlier predictions on the consequences of H-poor, C/O-rich accretion disc on reflection-induced fluorescent lines in the spectra of UCXBs.
A comparative study of satellite galaxies in Milky Way-like galaxies from HSC, DECaLS, and SDSS
Authors: Wang Wenting , Takada Masahiro , Li Xiangchong , Carlsten Scott G , Lan Ting-Wen , Shi Jingjing , Miyatake Hironao , More Surhud , Beaton Rachael L , Lupton Robert , Lin Yen-Ting , Qiu Tian , Luo Wentao
Published: November 2020

We conduct a comprehensive and statistical study of the luminosity functions (LFs) for satellite galaxies, by counting photometric galaxies from HSC, DECaLS, and SDSS around isolated central galaxies (ICGs) and paired galaxies from the SDSS/DR7 spectroscopic sample. Results of different surveys show very good agreement. The satellite LFs can be measured down to MV ∼ −10, and for central primary galaxies as small as 8.5 < log10M*/M⊙ < 9.2 and 9.2 < log10M*/M⊙ < 9.9, which implies there are on average 3–8 satellites with MV < −10 around LMC-mass ICGs. The bright end cutoff of satellite LFs and the satellite abundance are both sensitive to the magnitude gap between the primary and its companions, indicating galaxy systems with larger magnitude gaps are on average hosted by less massive dark matter haloes. By selecting primaries with stellar mass similar to our Milky Way (MW), we discovered that (i) the averaged satellite LFs of ICGs with different magnitude gaps to their companions and of galaxy pairs with different colour or colour combinations all show steeper slopes than the MW satellite LF; (ii) there are on average more satellites with −15 < MV < −10 than those in our MW; (iii) there are on average 1.5 to 2.5 satellites with MV < −16 around ICGs, consistent with our MW; (iv) even after accounting for the large scatter predicted by numerical simulations, the MW satellite LF is uncommon at MV > −12. Hence, the MW and its satellite system are statistically atypical of our sample of MW-mass systems. In consequence, our MW is not a good representative of other MW-mass galaxies. Strong cosmological implications based on only MW satellites await additional discoveries of fainter satellites in extra-galactic systems. Interestingly, the MW satellite LF is typical among other MW-mass systems within 40 Mpc in the local Universe, perhaps implying the Local Volume is an underdense region.
Introduction
Authors: Kaji Masanori , kragh Helge
Published: November 2020

Even though there have already been many studies of the reception of scientific discoveries and theories, only a few discoveries have been systematically examined from a comparative perspective, in particular Darwin’s theory of evolution in biology and Einstein’s relativity theory in physics. In the field of chemistry, the periodic system of the elements is a good candidate for such comparative reception studies. Although the discovery of the periodic system and its later history have generated numerous inquiries, its reception has received only partial or scanty attention. In his noted paper published in 1996, the American historian of science Stephen G. Brush explored the role that successful predictions and accommodation of known facts played in persuading scientists to accept scientific discoveries. He systematically examined textbooks and comprehensive chemistry reference works, observing that, “[the] number of explicit references to the periodic law to be found in late nineteenth-century chemistry journals is small and fluctuates irregularly.” Relying on a survey of textbooks and reference works written between 1871 and 1890 and existing in American libraries, he concluded that the periodic law had been generally accepted in the United States and Britain by 1890. In a footnote to the same paper, he suggested the need to extend this study of texts to other countries, especially Germany and France. In fact, two years before Brush’s paper was published, Ludmilla Nekoval-Chikhaoui had completed her dissertation on the diffusion of Mendeleev’s periodic classification in France. She studied this subject as part of a project on the diffusion of scientific knowledge from the second half of the nineteenth century to the early twentieth century. Basing her examination on scientific journals and chemistry books, Nekoval-Chikhaoui analyzed the diffusion of the periodic system in the French scientific community. She also surveyed the introduction of periodic classification in higher and secondary education based on an analysis of chemistry textbooks, higher education courses, and public education programs. At the end of her dissertation, she called to conduct a comparative analysis of the diffusion of Mendeleev’s discovery in different European countries.
The Periodic System and Its Influence on Research and Education in Germany between 1870 and 1910
Authors: Boeck Gisela
Published: November 2020

In 1895 Karl Seubert (1851–1942) published some of the most important papers by Lothar Meyer (1830–1895) and Dmitrii I. Mendeleev (1834–1907) on the so-called natural system of elements. He wrote: . . . At first it seems incomprehensible to today’s reader of these essays that the general reception of the system was delayed for many years even though it was presented in a final form and its benefit for theoretical, practical and pedagogical purposes had been explained in detail. . . . Seubert discovered a lack of interest in the field of inorganic chemistry, but also an inadequate description of the system. He remarked that Meyer’s explanations were too short, and Mendeleev’s too circuitous. The system became a resounding success when the deductions which were drawn from it were confirmed by experiments in rapid succession: the selection of the atomic weight with respect to the known number of equivalents, as in the case of indium and uranium; the change in the order, regardless of the valid atomic weights, such as the platinum group; and, last but not least, the prediction of new elements and their chemical properties which were proved true with the discoveries of scandium, gallium and germanium quickly one after the other. The brilliant vision and the boldness of Mendelejeff led the system to its unquestioned victory. Seubert was Meyer’s colleague for many years. From 1878 to 1895, they worked together on the redetermination of atomic weights and published several papers on this topic. Seubert was the first biographer to write about Meyer and was responsible for publishing his most important papers. Nevertheless, Seubert regarded Mendeleev’s role in the discovery of the periodic system to be of greater importance. This is shown by the last sentence of the previously quoted passage. Seubert’s remark elicits two questions: First, why did Seubert consider Meyer’s role in the discovery of the periodic system as less important? Second, was its reception in Germany truly delayed? These questions are connected to several different factors: politics within German chemistry; didactic approaches to teaching chemistry in schools and universities; and the role of the periodic system in the public sphere.
Organic Synthesis
Authors: Taber Douglass F. , Lambert Tristan
Published: November 2020

Organic Synthesis: State of the Art 2011-2013 is a convenient, concise reference that summarizes the most important current developments in organic synthesis, from functional group transformations to complex natural product synthesis. The fifth volume in the esteemed State of the Art series, the book compiles two years' worth of Douglass Taber's popular weekly column Organic Chemistry Highlights. The series is an invaluable resource, leading chemists quickly and easily to the most significant developments in the field. The book is logically divided into two sections: the first section focuses on specific topics in organic synthesis, such as C-N Ring Construction and Carbon-Carbon Bond Formation. Each topic is presented using the most significant publications within those areas of research. The journal references are included in the text. The second section focuses on benchmark total syntheses, with an analysis of the strategy for each, and discussions of pivotal transformations. Synthetic organic chemistry is a complex and rapidly growing field, with additional new journals appearing almost every year. Staying abreast of recent research is a daunting undertaking. This book is an ideal tool for both practicing chemists and students, offering a rich source of information and suggesting fruitful pathways for future investigation.
Reduction and Oxidation
Authors: Taber Douglass F.
Published: November 2020

Craig M. Williams of the University of Queensland and John Tsanaktsidis of CSIRO Victoria decarboxylated (Org. Lett. 2011, 13, 1944) the acid 1 to the hydrocarbon 2 by coupling the crude acid chloride, formed in CHCl3, with 3 while irradiating with a tungsten bulb. In a related development, David C. Harrowven of the University of Southampton showed (Chem. Commun. 2011, 46, 6335, not illustrated) that tin residues can be removed from a reaction mixture by passage through silica gel containing 10% K2CO3. Sangho Koo of Myong Ji University selectively removed (Org. Lett. 2011, 13, 2682) the allylic oxygen of 5, leaving the other protected alcohol. Donald Poirier of Laval University reduced (Synlett 2011, 2025) the nitrile of 7 to a methyl group. Kiyotomi Kaneda of Osaka University prepared (Chem. Eur. J. 2010, 16, 11818; Angew. Chem. Int. Ed. 2011, 50, 2986) supported Au nanoparticles that deoxygenated an epoxide 9 to the alkene 10. Epoxides of cyclic alkenes also worked well. Shahrokh Saba of Fordham University aminated (Tetrahedron Lett. 2011, 52, 129) the ketone 11 by heating it with an amine 12 in the presence of ammonium formate. Shuangfeng Yin and Li-Biao Han of Hunan University devised (J. Am. Chem. Soc. 2011, 133, 17037) catalyst systems that reduced the alkyne 14 selectively to either the Z or the E product. Professor Kaneda uncovered (Chem. Lett. 2011, 40, 405) a reliable Pd catalyst for the hydrogenation (not illustrated) of an alkyne to the Z alkene. David R. Spring of the University of Cambridge established (Synlett 2011, 1917) biphasic reaction conditions for the conversion of 16 to the azide 18 that were compatible with the base-sensitive Fmoc protecting group. Noritaka Mizuno of the University of Tokyo developed (J. Org. Chem. 2011, 76, 4606) a Ru catalyst for the transformation of an alkyl azide 19 to the nitrile 20. Chi-Ming Che of the University of Hong Kong (Synlett 2011, 1174) and Philip Wai Hong Chan of Nanyang Technological University (J. Org. Chem. 2011, 76, 4894) independently oxidized an aldehyde 21 to the amide 22.
Functional Group Protection
Authors: Lambert Tristan H.
Published: November 2020

Martin D. Burke at the University of Illinois at Urbana-Champaign reported (Nature Chem. 2012, 4, 996) that the amphotericin B derivative 1 could be site-selectively acylated at the C15, C4′, or C2′ hydroxyls by electronic tuning of the acylating agent (e.g., 2 leading to 3). Another impressive example of selective protection was disclosed (Nature Chem. 2012, 4, 789) by Andreas Herrmann at the Zernike Institute for Advanced Materials, who found that RNA aptamers such as 5 selectively bind to neomycin 4, leaving only one of the amino groups exposed for acylation to selectively furnish, for example, 7. A convenient new benzylating reagent called TriBOT (9) was introduced (Org. Lett. 2012, 14, 5026) by Munetaka Kunishima at Kanazawa University and was shown to be useful for the benzylation of alcohols such as 8. Subhash P. Chavan at the National Chemical Laboratory in India reported (Tetrahedron Lett. 2012, 53, 4683) a very practical method for PMB protection of alcohols including 11 using simply p-anisyl alcohol and Amberlyst-15. For PMB deprotection, Aurélien Blanc and Patrick Pale at the University of Strasbourg reported (J. Org. Chem. 2012, 77, 9227) that use of catalytic AgSbF6 and trimethoxybenzene (14) is a mild and effective method, even in the context of potentially sensitive substrates such as 13. The deprotection of tosylated amines is a classic problem in synthesis. Now Katsuhiko Tomooka at Kyushu University has developed (J. Am. Chem. Soc. 2012, 134, 19358) a unique strategy involving nucleophilic attack at nitrogen by phosphide anion, a process that readily lends itself to the conversion of substrates such as 16 to (for example) carbamate 17. Propylphosphonic anhydride (T3P) was found (Tetrahedron Lett. 2012, 53, 5030) by John Kallikat Augustine and Pujari Vijaykumar at Syngene International Ltd. in India to catalyze the acetalization of aldehydes such as 18 under essentially neutral conditions. Interestingly, acetalization of aldehydes and ketones, including 20, under basic conditions using N-hydroxybenzenesulfonimide was reported (Synlett 2012, 23, 2773) by Alfred Hassner at Bar-Ilan University in Israel.
C–H Functionalization
Authors: Taber Douglass F.
Published: November 2020

Konstantin P. Bryliakov of the Boreskov Institute of Catalysis devised (Org. Lett. 2012, 14, 4310) a manganese catalyst for the selective tertiary hydroxylation of 1 to give 2. Note that the electron-withdrawing Br deactivates the alternative methine H. Bhisma K. Patel of the Indian Institute of Technology, Guwahati selectively oxidized (Org. Lett. 2012, 14, 3982) a benzylic C–H of 3 to give the corresponding benzoate 4. Dalibor Sames of Columbia University cyclized (J. Org. Chem. 2012, 77, 6689) 5 to 6 by intramolecular hydride abstraction followed by recombination. Thomas Lectka of Johns Hopkins University showed (Angew. Chem. Int. Ed. 2012, 51, 10580) that direct C–H fluorination of 7 occurred predominantly at carbons 3 and 5. John T. Groves of Princeton University reported (Science 2012, 337, 1322) an alternative manganese porphyrin catalyst (not illustrated) for direct fluorination. C–H functionalization can also be mediated by a proximal functional group. John F. Hartwig of the University of California, Berkeley effected (J. Am. Chem. Soc. 2012, 134, 12422) Ir-mediated borylation of an ether 9 in the position β to the oxygen to give 10. Uttam K. Tambar of the UT Southwestern Medical Center devised (J. Am. Chem. Soc. 2012, 134, 18495) a protocol for the net enantioselective amination of 11 to give 12. Conversion of a C–H bond to a C–C bond can be carried out in an intramolecular or an intermolecular sense. Kilian Muñiz of the Catalan Institution for Research and Advanced Studies cyclized (J. Am. Chem. Soc. 2012, 134, 15505) the terminal alkene 13 directly to the cyclopentene 15. Olivier Baudoin of Université Claude Bernard Lyon 1 closed (Angew. Chem. Int. Ed. 2012, 51, 10399) the pyrrolidine ring of 17 by selective activation of a methyl C–H of 16. Jeremy A. May of the University of Houston found (J. Am. Chem. Soc. 2012, 134, 17877) that the Rh carbene derived from 18 inserted into the distal alkyne to give a new Rh carbene 19, which in turn inserted into a C–H bond adjacent to the ether oxygen to give 20.