bluuebunny/crossref_metadata_2025 huggingface dataset:
MnI complex redox potential tunability by remote lewis acid interaction
Authors: Srinivasan Anandi , Campos Jesús , Giraud Nicolas , Robert Marc , Rivada-Wheelaghan Orestes
Published: July 2020

MnI-Complex electronic tuneability through remote interactions. Introducing 2-pyridone based ligands as redox tuner in molecular electrocatalysis.
Droplet delivery and nebulization system using surface acoustic wave for mass spectrometry
Authors: Sun Di , Böhringer Karl F. , Sorensen Matthew , Nilsson Erik , Edgar J. Scott , Goodlett David R.
Published: July 2020

We present a piezoelectric transducer for standing wave surface acoustic wave nebulization (SW-SAWN) patterned with anisotropic ratchet conveyors (ARCs) to automate the sample preparation and droplet delivery.
Anion-templated assembly of multinuclear copper(ii)–triazole complexes
Authors: Gopalakrishnan Mohan , Krittametaporn Nuttaporn , Yoshinari Nobuto , Konno Takumi , Sangtrirutnugul Preeyanuch
Published: July 2020

Anions were used as templates to construct copper(ii) clusters with different architectures.
Self-assembly of four generations of RNA dendrimers for drug shielding with controllable layer-by-layer release
Authors: Li Xin , Vieweger Mario , Guo Peixuan
Published: July 2020

Multifunctional RNA dendrimers have been developed as novel drug delivery platforms, which show shielding effect of loaded cargos and temperature triggered stepwise dissociation.
A FRET-based upconversion nanoprobe assembled with an electrochromic chromophore for sensitive detection of hydrogen sulfide in vitro and in vivo
Authors: Cui Mengyuan , Li Haonan , Ren Xiangyu , Xia Lili , Deng Dawei , Gu Yueqing , Li Dahong , Wang Peng
Published: July 2020

A FRET-based upconversion nanoprobe assembled with an electrochromic chromophore was rationally designed for hydrogen sulfide detection in vitro and in vivo.
Trisulfonamide calix[6]arene-catalysed Michael addition to nitroalkenes
Authors: Cera Gianpiero , Balestri Davide , Bazzoni Margherita , Marchiò Luciano , Secchi Andrea , Arduini Arturo
Published: July 2020

We report a Michael addition of indoles to nitroalkene derivatives enabled by hydrogen-bonding interactions between trisulfonamide (TSA) calix[6]arene catalysts and protic solvents.
Discovery and properties of a new indigoid structure type based on dimeric cis-indigos
Authors: Hong Hyejin , Conover Cassidy M. , Hofsommer Dillon T. , Sanz Corey A. , Hicks Robin G.
Published: July 2020

Reactions of indigo with quinones in the presence of NaH leads to products containing two indigo subunits; one indigo is in a cis configuration and fused via its indole nitrogen atoms to a second indigo at the central C–C bond of the latter.
Correction: Rapid sodium periodate cleavage of an unnatural amino acid enables unmasking of a highly reactive α-oxo aldehyde for protein bioconjugation
Authors: Brabham Robin L. , Keenan Tessa , Husken Annika , Bilsborrow Jacob , McBerney Ryan , Kumar Vajinder , Turnbull W. Bruce , Fascione Martin A.
Published: July 2020

Correction for ‘Rapid sodium periodate cleavage of an unnatural amino acid enables unmasking of a highly reactive α-oxo aldehyde for protein bioconjugation’ by Robin L. Brabham et al., Org. Biomol. Chem., 2020, 18, 4000–4003, DOI: 10.1039/D0OB00972E.
Thermodynamic investigation with chemical kinetic analysis on the reoxidation phenomenon of the Cr(iii) in air
Authors: Liu Qining , Liu Honghui , Chen Huixia , Wang Xinrun , Hu Dahai , Cheng Xichuan , Xu Hongbin
Published: July 2020

In this paper, the reoxidation behaviours of CrOOH and Cr(OH)3 are investigated as the major reduction products of Cr(vi).
Novel drug isolated from mistletoe (1E,4E)-1,7-bis(4-hydroxyphenyl)hepta-1,4-dien-3-one for potential treatment of various cancers: synthesis, pharmacokinetics and pharmacodynamics
Authors: Hong Jing , Meng Lin , Yu Peipei , Zhou Ceng , Zhang Zhaoyan , Yu Zhiguo , Qin Feng , Zhao Yunli
Published: July 2020

(1E,4E)-1,7-Bis(4-hydroxyphenyl)hepta-1,4-dien-3-one (DHDK) is a novel curcuminoid analogue isolated from mistletoe. We report the chemical total synthesis, pharmacokinetics, pharmacodynamics, and toxicity on normal cells, cancer cells, liver and kidney.
Thermally reduced mesoporous manganese MOF @reduced graphene oxide nanocomposite as bifunctional electrocatalyst for oxygen reduction and evolution
Authors: Wahab Abdul , Iqbal Naseem , Noor Tayyaba , Ashraf Sheeraz , Raza Muhammad Arslan , Ahmad Awais , Khan Usman Ali
Published: July 2020

Oxygen electrocatalysis plays a crucial role in harnessing energy from modern renewable energy technologies like fuel cells and metal–air batteries.
Investigation of strain and doping on the electronic properties of single layers of C6N6 and C6N8: a first principles study
Authors: Bafekry Asadollah , Nguyen Chuong V. , Goudarzi Abbas , Ghergherehchi Mitra , Shafieirad Mohsen
Published: July 2020

Using first-principles calculations, we explore the effects of atom doping and strain on the structural, electronic, and magnetic properties of C6N6 and C6N8 monolayers.
Mechanistic pathways for the degradation of SMX drug and floatation of degraded products using F–Pt co-doped TiO2 photocatalysts
Authors: Jahdi Majid , Mishra Shivani B. , Nxumalo Edward N. , Mhlanga Sabelo D. , Mishra Ajay K.
Published: July 2020

This work presents smart pathways to enhance the photocatalytic activity of TiO2via co-doping with fluorine (F) and platinum (Pt) to form F–Pt co-doped TiO2 photocatalysts and investigates the unique and unusual fluorination of the floated products.
A method for real time detection of reaction endpoints using a moving window t-test of in situ time course data
Authors: DiMaso Elyse N. T. , Bondi Robert W. , Guo John , O'Brien Alexander G.
Published: July 2020

In-line Fourier transform mid-infrared spectroscopy (FTIR) in combination with a moving window t-test method was used to determine the endpoint of a reaction with a highly inconsistent rate.
Tumor microenvironment-oriented adaptive nanodrugs based on peptide self-assembly
Authors: Li Shukun , Zhang Wenjia , Xue Huadan , Xing Ruirui , Yan Xuehai
Published: July 2020

The tumor microenvironment is of significance to promote release or reorganization of peptide-modulated nanodrugs, optimizing drug bioavailability and therapeutic outcome.
Statistical mechanics of a double-stranded rod model for DNA melting and elasticity
Authors: Singh Jaspreet , Purohit Prashant K.
Published: July 2020

The double-helical topology of DNA observed at room temperature in the absence of any external loads can be disrupted by increasing the bath temperature or by applying tensile forces, leading to spontaneous strand separation known as DNA melting.
Factors controlling the pinning force of liquid droplets on liquid infused surfaces
Authors: Sadullah Muhammad Subkhi , Panter Jack R. , Kusumaatmaja Halim
Published: July 2020

Liquid infused surfaces with partially wetting lubricants have recently been exploited for numerous intriguing applications. Here, we study the factors that control the pinning force and the contact angle hysteresis of liquid droplets on liquid infused surfaces.
Programming stiff inflatable shells from planar patterned fabrics
Authors: Siéfert Emmanuel , Reyssat Etienne , Bico José , Roman Benoît
Published: July 2020

Origami-inspired design of Gaussian morphing fabrics structures. Superimposed flat and inextensible fabric sheets are heat-sealed along a specific pattern of lines. Upon inflation, this network of tubular cavities deploys into a large, stiff and light shell, with a programmed shape.
Searching for stable perovskite solar cell materials using materials genome techniques and high-throughput calculations
Authors: Sun Qingde , Yin Wan-Jian , Wei Su-Huai
Published: July 2020

A summary of four classes of perovskites and their representatives, considering the stability and PV properties for each type of perovskite.
A novel two-dimensional oxysulfide Sr3.5Pb2.5Sb6O5S10: synthesis, crystal structure, and photoelectric properties
Authors: Wang Ruiqi , Bu Kejun , Zhang Xian , Gu Yuhao , Xiao Yi , Zhan Zhaohuang , Huang Fuqiang
Published: July 2020

A novel two-dimensional (2D) oxysulfide Sr3.5Pb2.5Sb6O5S10 with a band gap of 1.34 eV possesses notable photoelectric properties under irradiation.
A novel near-infrared LiGaW2O8:Yb3+, Cr3+ up-conversion phosphor with enhanced luminescence intensity based on Ho3+/Er3+ bridges
Authors: Zhou Jun , Xia Zhiguo , Li Xiong , Yun Xiangyan , Sun Jiayue , Xu Denghui
Published: July 2020

An enhanced near-infrared emission can be achieved by Ho3+/Er3+ energy transfer bridges in LiGaW2O8:Yb3+, Ho3+/Er3+, Cr3+ up-conversion phosphors.
Vaginal microbiome analysis of healthy women during different periods of gestation
Authors: Li Dan , Chi Xin-Zuo , Zhang Lei , Chen Rui , Cao Jing-rong , Sun Xiao-yan , Yang He-qin , Liao Qin-ping
Published: July 2020

To assess the vaginal microbiome throughout full-term uncomplicated pregnancy, a longitudinal study was designed for 12 healthy women who had prepared to become pregnant and then delivered at term (38–42 weeks) without complications. The vaginal microbial community was studied at pre-pregnancy, 8–12, 24–28, 37–38 weeks of gestation, and puerperium, using hypervariable tag sequencing of the V3–V4 region of the 16S rRNA gene. Sequencing produced approximately 10 million reads on the Illumina MiSeq. Members of the Firmicutes phyla were prevailing before and during pregnancy periods, and the proportion was quite as Proteobacteria until puerperium. Lactobacillus genus was abundant before and during pregnancy, but post-delivery vaginal microflora variety turned diverse. The species-level analysis revealed that a healthy vaginal microbiome before or during pregnancy was prominently dominated by Lactobacillus crispatus. Furthermore, PCoA analysis revealed for differences in the bacterial community composition between the two levels of Lactobacillus species in pre-pregnancy and pregnancy period (PC1 contribution of 58.46%, PC3 contribution of 8.64%). Based on the taxonomic and PCoA analysis, we found that L. crispatus was dominant in the vaginal microflora of healthy women before or during pregnancy, but at the puerperium, the status changed leading to decreased abundance of protective Lactobacillus species that made vaginal micro-ecological barrier vulnerable to diseases. Additionally, vaginal pH was an important environmental property affecting the vaginal microbial community.
HMGB1 A box protects neurons by potently inhibiting both microglia and T cell-mediated inflammation in a mouse Parkinson’s disease model
Authors: Tian Yu , Cao Yuwen , Chen Rong , Jing Yufeng , Xia Lin , Zhang Shiqing , Xu Huaxi , Su Zhaoliang
Published: July 2020

In the subacute Parkinson’s disease (PD) mice model of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), injection of HMGB1 competitive inhibitor protein HMGB1 A box and the ethyl pyruvate (EP) that inhibit the release of HMGB1 from cells restored the number of dopaminergic neurons and TH+ fibers in the SN and striatum. Our data show that A box up-regulated CD200-CD200R signal of microglia inhibited the activation of microglia mediated by HMGB1, and the production of TNF-α, IL-1β and IL-6 in vivo and in vitro mixed culture system. Microglia overexpressing CD200R produced less inflammatory chemokines and reduced the loss of TH+ neurons. In addition, HMGB1 A box decreased the level of CCL5 and significantly inhibited the infiltration of almost all T cells including Th17 and the proportion of Th17 in CD4+ T cells. In vitro MPP+ induced model and HMGB1-stimulated mesencephalic cell system activated microglia induced the differentiation of naïve T cells to Th17, and A box significantly inhibited this process. To sum up, our results show that HMGB1 A box targeting HMGB1, which effectively reduces the activation of microglia in MPTP PD model by restoring CD200-CD200R signal inhibit microglia mediated neuroinflammation and the differentiation of T cells to Th17.
The Gaia-ESO Survey: Spectroscopic-asteroseismic analysis of K2 stars in Gaia-ESO
Authors: Worley C. C. , Jofré P. , Rendle B. , Miglio A. , Magrini L. , Feuillet D. , Gavel A. , Smiljanic R. , Lind K. , Korn A. , Gilmore G. , Randich S. , Hourihane A. , Gonneau A. , Francois P. , Lewis J. , Sacco G. , Bragaglia A. , Heiter U. , Feltzing S. , Bensby T. , Irwin M. , Gonzalez Solares E. , Murphy D. , Bayo A. , Sbordone L. , Zwitter T. , Lanzafame A. C. , Walton N. , Zaggia S. , Alfaro E. J. , Morbidelli L. , Sousa S. , Monaco L. , Carraro G. , Lardo C.
Published: July 2020

Context. The extensive stellar spectroscopic datasets that are available for studies in Galactic Archeaology thanks to, for example, the Gaia-ESO Survey, now benefit from having a significant number of targets that overlap with asteroseismology projects such as Kepler, K2, and CoRoT. Combining the measurements from spectroscopy and asteroseismology allows us to attain greater accuracy with regard to the stellar parameters needed to characterise the stellar populations of the Milky Way.

Aims. The aim of this Gaia-ESO Survey special project is to produce a catalogue of self-consistent stellar parameters by combining measurements from high-resolution spectroscopy and precision asteroseismology.

Methods. We carried out an iterative analysis of 90 K2@Gaia-ESO red giants. The spectroscopic values of Teff were used as input in the seismic analysis to obtain log g values. The seismic estimates of log g were then used to re-determine the spectroscopic values of Teff and [Fe/H]. Only one iteration was required to obtain parameters that are in good agreement for both methods and, thus, to obtain the final stellar parameters. A detailed analysis of outliers was carried out to ensure a robust determination of the parameters. The results were then combined with Gaia DR2 data to compare the seismic log g with a parallax-based log g and to investigate instances of variations in the velocity and possible binaries within the dataset.

Results. This analysis produced a high-quality catalogue of stellar parameters for 90 red giant stars from K2@Gaia-ESO that were determined through iterations between spectroscopy and asteroseismology. We compared the seismic gravities with those based on Gaia parallaxes to find an offset which is similar to other studies that have used asteroseismology. Our catalogue also includes spectroscopic chemical abundances and radial velocities, as well as indicators for possible binary detections.
Rotational dependence of turbulent transport coefficients in global convective dynamo simulations of solar-like stars
Authors: Warnecke J. , Käpylä M. J.
Published: July 2020

Context.For moderate and slow rotation, the magnetic activity of solar-like stars is observed to strongly depend on rotation, while for rapid rotation, only a very weak or no dependency is detected. These observations do not yet have a solid explanation in terms of dynamo theory.

Aims.We aim to find such an explanation by numerically investigating the rotational dependency of dynamo drivers in solar-like stars, that is, stars that have a convective envelope of similar thickness to that of the Sun.

Methods.We ran semi-global convection simulations of stars with rotation rates from 0 to 30 times the solar value, corresponding to Coriolis numbers, Co, of 0 to 110. We measured the turbulent transport coefficients contributing to the magnetic field evolution with the help of the test-field method, and compared with the dynamo effect arising from the differential rotation that is self-consistently generated in the models.

Results.The trace of theαtensor increases for moderate rotation rates with Co0.5and levels off for rapid rotation. This behavior is in agreement with the kineticαbased on the kinetic helicity, if one takes into account the decrease of the convective scale with increasing rotation. Theαtensor becomes highly anisotropic for Co ≳ 1. Furthermore,αrrdominates for moderate rotation (1 <  Co <  10), andαϕϕfor rapid rotation (Co ≳ 10). The effective meridional flow, taking into account the turbulent pumping effects, is markedly different from the actual meridional circulation profile. Hence, the turbulent pumping effect is dominating the meridional transport of the magnetic field. Taking all dynamo effects into account, we find three distinct regimes. For slow rotation, theαand Rädler effects are dominating in the presence of anti-solar differential rotation. For moderate rotation,αand Ω effects are dominant, indicative ofαΩ orα2Ω dynamos in operation, producing equatorward-migrating dynamo waves with a qualitatively solar-like rotation profile. For rapid rotation, anα2mechanism with an influence from the Rädler effect appears to be the most probable driver of the dynamo.

Conclusions.Our study reveals the presence of a large variety of dynamo effects beyond the classicalαΩ mechanism, which need to be investigated further to fully understand the dynamos of solar-like stars. The highly anisotropicαtensor might be the primary reason for the change of axisymmetric to non-axisymmetric dynamo solutions in the moderate rotation regime.
“Observations” of simulated dwarf galaxies
Authors: Rathi Shivangee , Mastropietro Michele , De Rijcke Sven , Gallart Carme , Bernard Edouard , Verbeke Robbert
Published: July 2020

Context. Apparent deviations between properties of dwarf galaxies from observations and simulations are known to exist, such as the “Missing Dwarfs” problem, the too-big-to-fail problem, and the cusp-core problem, to name a few. Recent studies have shown that these issues can at least be partially resolved by taking into account the systematic differences between simulations and observations.

Aims. This work aims to investigate and address any systematic differences affecting the comparison of simulations with observations.

Methods. To this aim, we analyzed a set of 24 realistically simulated Models of Realistic dwarfs In Action (MoRIA) dwarf galaxies in an observationally motivated way. We first constructed “observed” color-magnitude diagrams (CMDs) of the simulated dwarf galaxies in the typically used V- and I-bands. Then we used the synthetic CMD-fitting method to recover their star-formation histories (SFHs) from their observed CMDs. These solved SFHs were then directly compared to the true SFHs from the simulation star-particle data, mainly in terms of the star-formation rate (SFR) and the age-metallicity relation (AMR). We also applied a dust extinction prescription to the simulation data to produce observed CMDs affected by dust in the star-forming regions. Since future facilities, such as the James Webb Space Telescope and the European Extremely Large Telescope, will focus on the (near)-infrared rather than the optical, we also constructed and analyzed CMDs consisting of the I- and H- bands.

Results. We find a very good agreement between the recovered and the true SFHs of all the simulated dwarf galaxies in our sample, from the synthetic CMD analysis of their V − I versus I as well as the I − H versus H CMDs. Dust leads to an underestimation of the SFR during the last few hundred million years, with the strength and duration of the effect dependent on the dust content. Overall, our analysis indicates that quantities like SFR and AMR derived from the photometric observations of galaxies are directly comparable to their simulated counterparts, thus eliminating any systematic bias in the comparison of simulations and observations.
Statistical deprojection of intervelocities, interdistances, and masses in the Isolated Galaxy Pair Catalog
Authors: Nottale Laurent , Chamaraux Pierre
Published: July 2020

Aims. In order to study the internal dynamics of actual galaxy pairs, we need to derive the probability distribution function (PDF) of true 3D, orbital intervelocities and interdistances between pair members from their observed projected values along with the pair masses from Kepler’s third law. For this research, we used 13 114 pairs from the Isolated Galaxy Pair Catalog (IGPC).

Methods. The algorithms of statistical deprojection previously elaborated were applied to these observational data. We derived the orbital velocity PDFs for the whole catalog and for several selected subsamples. The interdistance PDF is deprojected and compared to the analytical profiles expected from semi-theoretical arguments.

Results. The PDF of deprojected pair orbital velocities is characterized by the existence of a main probability peak around ≈150 km s−1 for all subsamples of the IGPC as well as for the Uppsala Galaxy Pair Catalog. The interdistance PDFs of both the projected and deprojected data are described at large distances by the same power law with exponent ≈ − 2. The whole distributions, including their cores, are fairly fitted by King profiles. The mass deprojection yields a mass/luminosity ratio for the pairs of M/L = (30 ± 5) in solar units.

Conclusions. The orbital velocity probability peak is observed at the same value, ≈150 km s−1, as the main exoplanet velocity peak, which points toward a possible universality of Keplerian structures, whatever the scale. The pair M/L ratio is just seven times the standard ratio for luminous matter, which does not require the existence of nonbaryonic dark matter in these systems.
A significant mutual inclination between the planets within the π Mensae system
Authors: De Rosa Robert J. , Dawson Rebekah , Nielsen Eric L.
Published: July 2020

Context. Measuring the geometry of multi-planet extrasolar systems can provide insight into their dynamical history and the processes of planetary formation. These types of measurements are challenging for systems that are detected through indirect techniques such as radial velocity and transit, having only been measured for a handful of systems to date.

Aims. We aim to place constraints on the orbital geometry of the outer planet in the π Mensae system, a G0V star at a distance of 18.3 pc that is host to a wide-orbit super-Jovian (M sin i = 10.02 ± 0.15MJup) with a 5.7-yr period and an inner transiting super-Earth (M = 4.82 ± 0.85M⊕) with a 6.3-d period.

Methods. The reflex motion induced by the outer planet on the π Mensae star causes a significant motion of the photocenter of the system on the sky plane over the course of the 5.7-year orbital period of the planet. We combined astrometric measurements from the HIPPARCOS and Gaia satellites with a precisely determined spectroscopic orbit in an attempt to measure this reflex motion, and in turn we constrained the inclination of the orbital plane of the outer planet.

Results. We measure an inclination of ib = 49.9−4.5+5.3 deg for the orbital plane of π Mensae b, leading to a direct measurement of its mass of 13.01−0.95+1.03 MJup. We find a significant mutual inclination between the orbital planes of the two planets, with a 95% credible interval for imut of between 34.°5 and 140.°6 after accounting for the unknown position angle of the orbit of π Mensae c, strongly excluding a co-planar scenario for the two planets within this system. All orbits are stable in the present-day configuration, and secular oscillations of planet c’s eccentricity are quenched by general relativistic precession. Planet c may have undergone high eccentricity tidal migration triggered by Kozai-Lidov cycles, but dynamical histories involving disk migration or in situ formation are not ruled out. Nonetheless, this system provides the first piece of direct evidence that giant planets with large mutual inclinations have a role to play in the origins and evolution of some super-Earth systems.
Accretion of eroding pebbles and planetesimals in planetary envelopes
Authors: Demirci Tunahan , Wurm Gerhard
Published: July 2020

Wind erosion is a destructive mechanism that completely dissolves a weakly bound object like a planetesimal into its constituent particles, if the velocity relative to the ambient gas and the local gas pressure are sufficiently high. In numerical simulations we study the influence of such wind erosion on pebble and planetesimal accretion by a planetary body up to 10 REarth. Due to the rapid size reduction of an in-falling small body, the accretion outcome changes significantly. Erosion leads to a strong decrease in the accretion efficiency below a threshold size of the small body on the order of 10 m. This slows down pebble accretion significantly for a given size distribution of small bodies. The threshold radius of the small body increases with increasing planet radius and decreases with increasing semi-major axis. Within the parameters studied, an additional planetary atmosphere (up to 1 bar) is of minor importance.
Shape optimization of a Dirichlet type energy for semilinear elliptic partial differential equations
Authors: Henrot Antoine , Mazari Idriss , Privat Yannick
Published: July 2020

Minimizing the so-called “Dirichlet energy” with respect to the domain under a volume constraint is a standard problem in shape optimization which is now well understood. This article is devoted to a prototypal non-linear version of the problem, where one aims at minimizing a Dirichlet-type energy involving the solution to a semilinear elliptic PDE with respect to the domain, under a volume constraint. One of the main differences with the standard version of this problem rests upon the fact that the criterion to minimize does not write as the minimum of an energy, and thus most of the usual tools to analyze this problem cannot be used. By using a relaxed version of this problem, we first prove the existence of optimal shapes under several assumptions on the problem parameters. We then analyze the stability of the ball, expected to be a good candidate for solving the shape optimization problem, when the coefficients of the involved PDE are radially symmetric.
Seismic qualification by analysis of a nuclear class horizontal pressure vessel
Authors: Stan Liviu-Constantin , Călimănescu Ioan , Faitar Catalin
Published: July 2020

The seismic qualification for the structural strength it is an issue for the assessment of the seismic safety of the Nuclear Power Plants. The qualification for seismic events in nuclear industry [4] includes the assessment of the structural integrity and fitness for operability during and after an earthquake. Such qualifications are done for various safety and non-safety equipment among which the pressure vessels are of a paramount importance. The seismic qualification is done either directly on prototypes or scaled prototypes (mock ups) or via analytical methods like analysis with finite elements. In any case the model should accurately represent the actual performance of the component or structure when it is subjected to the prescribed effects. The goal of this article is to underline the procedure to be followed for nuclear industry horizontal pressure vessels in order to obtain sound and credible results for equipment seismic qualification by using the unique analysis features of ANSYS 19. A seismic qualification analysis is carried out for the horizontal pressure vessel. The seismic event is overloading the anchoring system beyond the ultimate strength of the material. The zone where these big stresses fields are calculated is at the anchors level. The vessel as designed failed to be qualified for the seism excitations imposed to the model. In order to have the vessel qualified the anchoring way should be redesigned. By comparing the overall calculated equivalent stresses with the tensile yield strength we may pull the conclusion that the original structure design will fail. Instead the new redesigned anchoring system with 8 extra-anchors will stand.
The amplitude influence on the thermal and hydraulic performances for a wavy air fin in a compact heat exchanger used in agriculture applications
Authors: Albeţel Septimiu , Rus Alexandru , David Eveline , Marţian Vlad
Published: July 2020

Wavy air fins are used in the construction of aluminum compact heat exchangers which are used in thermal equipment for agriculture, construction, and industrial applications. Since atmospheric air convective heat transfer coefficient is among the lowest of all fluids, there is a special interest in the optimizing of the geometry for this type of heat exchangers. One of the biggest challenges in designing cooling solutions for agriculture applications is the clogging effect on the performances of the heat exchangers. Clogging leads to a critical performance reduction of the compact heat exchanger used for these types of applications. This specific study, which was conducted in RAAL S.A company in collaboration with the University “Politehnica” of Timisoara”, checks the influence of the wavy air fin amplitude on the thermal and hydraulic performances and tries to find an optimum solution suitable for these specific projects. So, starting from the standard existing amplitude, different amplitude values were studied analytically. The analytical studies were further confirmed by real life measurements. The scope of the study was to find an optimal value for the amplitude that can further improve the overall performance of the aluminum compact heat exchangers and reduce the clogging effect.
Effects of CNG quantity on combustion characteristics and emissions of a dual fuelled automotive diesel engine
Authors: Rotaru Silviu , Pana Constantin , Negurescu Nicolae , Cernat Alexandru , Fuiorescu Dinu , Nuţu Cristian Nikolaos
Published: July 2020

The paper reveals some experimental aspects of compressed natural gas (CNG) use in dual fuel mode at an automotive diesel engine. Brake specific energetic consumption, incylinder pressure, emissions and variability of indicated mean effective pressure are analysed at operating regime of 2000 rpm and 40% load. Using CNG as an alternative fuel reduces brake specific energetic consumption by 50%, the CO2 emission by 10% and sets the in-cylinder maximum pressure 13 bar higher comparative to diesel fuel fuelling. The smoke and hydrocarbons emissions and the variability of indicated mean effective pressure are affected by the injection of compressed natural gas into intake manifold: HC emission grows 24 times, the smoke number and the coefficient of variability of IMEP double their values. The use of compressed natural gas at an automotive diesel engine improves its energetic performances and combustion process, having positive effects on CO2 emission and fuel consumption.
Researches on biofuels gasification using the Lurgi process with homogeneous air inlet over the combustion space
Authors: Lăzăroiu Gheorghe , Mihăescu Lucian , Negreanu Gabriel , Simion Iulia , Ciupăgeanu Dana-Alexandra
Published: July 2020

The experimental investigations carried out within the present research focus on a simple gasification technology dedicated to biofuels conversion according to the Lurgi procedure. Specifically, an installation with a fixed grill and a homogeneous distribution of the air inlet over the combustion space are considered. In order to provide a thorough background for the experimental research, this paper presents first the challenges related to the air distribution. If for coal gasification the difficulty of the homogeneous penetration of the air inlet within the whole combustion volume is balanced by the possibility of the direct emission of CO valorization, for biomass gasification this factor becomes fundamental. The original contribution of the technology introduced in this paper assumes an improved combustion process for Lurgi-type gas generators. The experimental installation employed has a particular design, enabling a homogeneous distribution of the air inlet over the entire combustion zone, up to the top of the embers layer. This allows achieving a maximum CO2 content in the flue gas flux, effectively reducing it inside the embers bed. The high calorific value of biofuels used favors developing an efficient combustion process, occurring at high temperatures. Thus, the reduction process of the CO2 is self-controlled. The experimental installation operates at a slow fuel rate, with discontinued supply and precise airflow control. The quality of the gas obtained is evaluated based on the resulting open flame, analyzing its composition.
Analysis of rotor' critical mode of operation to be employed in the design of a wind generation control unit
Authors: Fazylova Alina , Balbayev Gani , Ilieva Diana , Aliyarova Madina
Published: July 2020

This paper gives an overview and comparative characteristics of the main rotors available today, with properties suitable for the climatic conditions of Almaty and Almaty region, along with their critical mode of operation. A number of studies is carried out analysing the intrinsic features and capabilities of rotors, through which the problem of choosing an optimal rotor model for the subsequent design of a wind generator control unit is solved. One of these studies is a computer simulation of the main existing rotors operating in the same climatic conditions. The selected model must fully comply with the given environmental conditions of the selected area, in which the maximum wind speed and its critical value are set for all the studied rotor models. Thanks to the comparative studies on the technical characteristics of the most commonly used rotors, as well as to the modelling results, conclusions are drawn for the most effective and optimal choice to be employed in the design of a wind generator for the climatic conditions of the Almaty region.
Influence of four modern Flettner rotors, used as wind energy capturing system, on container ship stability
Authors: Vasilescu Mihail-Vlad , Voicu Ionut , Panait Cornel , Ciucur Violeta-Vali
Published: July 2020

This article is presenting the influence on the stability of a container ship, by connecting four modern Flettner rotors, as wind energy capturing system. Modern Flettner rotors, are energy power generators. They are one of the various equipment used to capture and harness wind energy. By reading the article, the reader can discover what are the forces which influence the modern Flettner rotors and how they influence the ship stability.This article major points are: calculation the influence of the modern Flettner rotors on the ship transverse and longitudinal stability, calculation of the ship new displacement, new draft, new metacentric height and period of rolling.
Influence of Flettner balloon, used as wind energy capturing system, on container ship stability
Authors: Vasilescu Mihail-Vlad , Dinu Dumitru
Published: July 2020

This article presents the influence on the stability of a container ship, by connecting a Flettner balloon, as wind energy capturing system. Flettner balloon is a generator of electric power, filled with helium that rotates around a horizontal axis and sends the electricity using a cable. It rotates around a horizontal axis in response to the wind, effectively generating clean, renewable electricity at a lower cost than all competing systems. These article major points determined by the authors are: calculation of the forces which influence the balloon, calculation the influence of the balloon on the ship transverse and longitudinal stability, calculation of the ship new displacement, new draft, new GM and period of rolling. As a conclusion of the article, the reader will discover that the transverse stability of the ship will insignificant decreased with a small value of 0.01 and the longitudinal stability will be improved by 0.7532. The article demonstrates that a Flettner balloon, installed on a container ship, is a possible concept of capturing wind energy.
Researches on the development of an optical system for improving the efficiency of photovoltaic panels
Authors: Rizescu Dana , Rizescu Ciprian Ion , Alionte Cristian Gabriel
Published: July 2020

The paper aims to create a unit using Fresnel lenses. This module consist of an arrangement of planar-convex Fresnel lenses, made of methyl polymethacrylate, mounted in a hexagonal raster and bent to form a dome for collecting and amplifying solar radiation at several focal points and with the possibility of adjusting the focal distance. The module has three aluminum alloy legs that are vertically adjustable. This construction using Fresnel lenses mounted in a hexagonal raster will increase the energy collected by a photovoltaic panel, thus significantly reducing energy losses and long-term costs. Compared to normal lenses, these lenses are considerably lighter because the material in the center of the lens is reduced, and for manufacturing can be used methyl polymethacrylate or polycarbonate, thus greatly reducing manufacturing costs. To show the functioning of the unit the authors presents in the paper a MATLAB simulation of the Fresnel lens model and a ray propagation.
Simulation analysis of thermal performance of the solar air/water collector by using computational fluid dynamics
Authors: Shandal Jafer , Abed Qahtan A. , Al-Shamkhee Dhafer M.
Published: July 2020

Utilizing solar energy has received a giant activity by energy applications into distinctive states within the world. The sun is regarded strong supply providing uninterrupted coherent energy. In this research, simulation study has been done to estimate the performance of dual purpose solar collector (DPSC). Flat plate dual purpose solar collector with dimensions (194 cm length, 95 cm width and 14 cm thickness) has been used for heating the air and water for different using. Rectangular fins are used in air duct to increase heat transfer coefficient in air heater part. COMSOL Multiphysics 5.4 computer program has been used to calculate the theoretical results. Many parameters such as a different flow rate and temperatures for the inlet working fluids are investigated.
Soil moisture influence in the soil tillage operations
Authors: Cardei Petru , Sfiru Raluca , Muraru Sebastian , Condruz Paula
Published: July 2020

This article presents results obtained by the author in an attempt to introduce new parameters that influence the working process of agricultural soil working machines, in the classical formulas that mathematically model the tillage draft force. This article naturally introduces soil moisture. To introduce soil moisture into the calculation formulas of the tillage draft force, other physical parameters affected by soil moisture were used: density, cohesion, adhesion, etc. In this article, is explicitly describes, only the variation of soil density with its moisture. Considering some phenomena such as soilswellingorshrinkage, required the development of an adequate mathematical model of the expression of the density of soil-water mixture, concerning the concentration of water and the densities of dry soil and water. The final formulas obtained are tested to experimental results from the literature. Finally, the author sets out his opinion regarding the use of the results in design calculations and regarding the elevation to the rank of physical law of a mathematical model represented by a formula with a large number of parameters, which in turn are still dependent on many others parameters.
Sorghum bicolor (L.) Moench. - Plant for the future in Moldavia agriculture (Romania) and for the human nutrition
Authors: Isticioaia Simona-Florina , Leonte Alexandra , Popa Lorena-Diana , Trotuş Elena , Apostol Livia , Voicea Iulian , Matei Gheorghe
Published: July 2020

In the climatic conditions of the Center of Moldavia (Romania), there are eight sorghum hybrids cultivated for grains (Arsky, Foehn, Albanus, Shamal, Kalatur şi Armorik, Elan and Alimentar) in order to establish their adaptability to the conditions of the area, by taking into account the current problems of agriculture caused by climate change and the need to find a solutions to fight hunger and improve human health. This study focused on two directions, namely: identifying genotypes that achieve the highest productions and establishing food value and the benefits of sorghum grains on human health by analysing the physico chemical composition of the grains, by determining the mineral content of the grain and by determining the composition in amino acids. The grain production had ranged from 8623 kg/ha to 11181 kg/ha. This production had characterized by a protein content between 8.84 % and 12.80 %, in lipid content between 3.39 % and 4.15 %, in raw fibre content between 2.15 % and 3.95 % and the starch content was between 66.70 % and 74.66 %. The analysed mineral content of the sorghum samples has the following values (mg/100g a.s.): phosphorus - 280 - 330; potassium - 520 - 610; calcium - 2.4 - 3.9; magnesium - 260 - 290; iron - 11.6 - 18.9; zinc - 1.94 - 2.42; copper - 0.23 - 0.36; manganese - 1.60 - 1.97. Analysing the amino acid composition of sorghum samples it can be said that the samples contain all the essential amino acids, in concentrations that, some of them, exceed the recommended daily dose (FAO/WHO/UNU): leucine, isoleucine, histidine, valine. Also the analysed sorghum seeds add an important content of methionine, threonine and phenylalanine.
Evaluation of hand transmitted chainsaw vibrations during wood cutting
Authors: Matache Mihai Gabriel , Munteanu Mariana , Dumitru Dragos Nicolae , Epure Mariana
Published: July 2020

Forestry workers are exposed to vibrations from chainsaws which usually are not taken into consideration from the negative impact point of view on their health. However, in time, these vibrations could cause trepidation disease which will affect the worker neuro-muscular and locomotory apparatus. One mean to mitigate the vibrations impact is to measure and determine the worker’s exposure level to vibrations during worktime and to dispose the proper measures to reduce their negative impact. Within this paper will be presented experimental results obtained for vibration data recorded on a chainsaw during wood cutting in real life conditions. The equivalent vibration was measured at both front and end handles level and the biggest value was used for calculation of the human exposure level.
Climate changes and methods to protect vegetable crops
Authors: Muscalu Adriana , Tudora Cătălina , Coţa Constantin , Gyorgy Zoltan , Burnichi Floarea , Bârsan Mariana
Published: July 2020

In the context of the current climate change, it has become urgently necessary to develop adequate systems to protect horticultural crops. In Romania, the losses caused to these cultures by the extreme weather phenomena, as well as the lack of active intervention measures to combat or limit them, represent the main argument for addressing this field in particular. Vegetable crops are generally sensitive to extreme weather phenomena. In the climatic conditions in our country, the extreme phenomena occur between March and September, which coincides with the vegetation period of the crops. Of these, hail causes significant damage, and in some cases, at high intensity and long-lasting, can cause the calamity of vegetable crops. Another effect can arise in the drought years, when, in the absence of rainfall, the weeds enter into a fierce competition with vegetables, as regards the specific consumption of water and nutrients. The paper presents a review regarding the current methods of vegetable crops protection against the extreme weather phenomena and of weed control in these crops, grown in organic system. Combining the available solutions, adopting integrated strategies for non-chemical weed control can be an important premise for researchers and farmers to protect vegetable crops.
Theoretical research to accomplish a system of ecological heating a greenhouse for vegetables
Authors: Marin Eugen , Mateescu Marinela , Manea Dragos , Dumitrascu Andrei , Vasilachi Carmen , Popa Radu , Popa Vlad
Published: July 2020

Considerating that the energy resources can be found in limited quantities and are not renewable, the most efficient and technically sustainable for heating the soil in early spring or late autumn in a greenhouse for vegetables is to use the solar energy. A heated greenhouse for vegetables is useful because the vegetation process can start more early or can continue later for can obtain several crops throughout the year. The paper presents theoretical researches accomplished for development an system of ecological heating in a greenhouse covered with a tough polyethylene wrap with triple layer. The heating system contains solar panels with heat-pipe vacuum tubes and an installation for heating the interior of the solarium using hot water hot air heaters, which adds more heat.
Analysis of the process of green hemp stalks sequential harvesting
Authors: Păun Anişoara , Stroescu Gheorghe , Zaica Alexandru , Ciupercă Radu , Bogdanof Constantin
Published: July 2020

HEMP (Cannabis Sativa - Industrial Hemp) is the industrial plant with the highest use of all these plants in the industry, since nothing is thrown away from this plant. Hemp is the plant of which everything is used, and the products obtained are of a great diversity, from the common rope to the medicinal or cosmetic substances, textiles, automotive or construction materials. It is an unpretentious plant because, apart from the fact that it wants a neutral PH and soils without excess humidity, no maintenance work need to be done and no extra care should be given. The fibre hemp is harvested at the technical maturity when the male plants shed the last pollen grains, and the stalks have a greenish-yellow colour and the leaves fell on the ground. Production management is different for an exclusive fibre production. If we look for raw materials that meet the demands of different areas of the economy with the lowest costs, we must take into account the reactivation of the hemp culture at the level of Romania, because, as we mentioned above, hemp is the plant of which everything is capitalised, and the products obtained are of a great diversity. By applying the technology for processing the stalks in green, the obtained fibre can be used with special results in the strawberry culture at the mulching operation. The paper presents the Equipment for harvesting green hemp stalks ERCV, equipment that performs sequential harvesting of hemp stalks leaving them on the ground. At the same time, factors that influence the process of harvesting hemp stalks are presented: harvesters’ cutting devices, kinematic of the cutting blades, cutting speed, cutting angles of the cutting blades, the forces acting on the blade and the power required to drive the cutting devices.
Finite element analysis of the compaction plate from a garbage truck
Authors: Voicu Gheorghe , Lazea Mircea , Constantin Gabriel-Alexandru , Stefan Elena-Madalina , Munteanu Mariana-Gabriela
Published: July 2020

Vehicles that collect and transport household waste are equipped with complex systems that perform the loading of the waste from the stationary collection containers, take over and pre-compact of material, compaction in the body of the structure and finally the landfill of the collected waste. Of all these operations, the compaction process is by far the most mechanically demanding. In this paper, the structural analysis of the compactor plate from a garbage truck is presented. In the first stage it was carried out parametric modelling of the assembly composed of compactor plate, counter pressure plate, the back of the garbage truck and to be compacted material. After assembly, the dynamic simulation of the compaction process in the garbage truck was performed, and the compaction mechanical stresses for the compactor plate were loaded in the Simulation module of the SolidWorks 2016 program. Here the finite element analysis was performed, resulting in the value and dispersion of the equivalent stresses (calculated by von Mises criterion), displacements and relative deformations of compactor plate from the analysed garbage truck.