bluuebunny/crossref_metadata_2025_split huggingface dataset:
Complex organic molecules in protoplanetary disks: X-ray photodesorption from methanol-containing ices
Authors: Basalgète R. , Dupuy R. , Féraud G. , Romanzin C. , Philippe L. , Michaut X. , Michoud J. , Amiaud L. , Lafosse A. , Fillion J.-H. , Bertin M. 
Published: January 2021

Context.Astrophysical observations show complex organic molecules (COMs) in the gas phase of protoplanetary disks. X-rays emitted from the central young stellar object that irradiate interstellar ices in the disk, followed by the ejection of molecules in the gas phase, are a possible route to explain the abundances observed in the cold regions. This process, known as X-ray photodesorption, needs to be quantified for methanol-containing ices. This Paper I focuses on the case of X-ray photodesorption from pure methanol ices.Aims.We aim at experimentally measuring X-ray photodesorption yields (in molecule desorbed per incident photon, displayed as molecule/photon for more simplicity) of methanol and its photo-products from pure CH3OH ices, and to shed light on the mechanisms responsible for the desorption process.Methods.We irradiated methanol ices at 15 K with X-rays in the 525–570 eV range from the SEXTANTS beam line of the SOLEIL synchrotron facility. The release of species in the gas phase was monitored by quadrupole mass spectrometry, and photodesorption yields were derived.Results.Under our experimental conditions, the CH3OH X-ray photodesorption yield from pure methanol ice is ~10−2molecule/photon at 564 eV. Photo-products such as CH4, H2CO, H2O, CO2, and CO also desorb at increasing efficiency. X-ray photodesorption of larger COMs, which can be attributed to either ethanol, dimethyl ether, and/or formic acid, is also detected. The physical mechanisms at play are discussed and must likely involve the thermalization of Auger electrons in the ice, thus indicating that its composition plays an important role. Finally, we provide desorption yields applicable to protoplanetary disk environments for astrochemical models.Conclusions.The X-rays are shown to be a potential candidate to explain gas-phase abundances of methanol in disks. However, more relevant desorption yields derived from experiments on mixed ices are mandatory to properly support the role played by X-rays in nonthermal desorption of methanol (see Paper II).
Endothelial β1 Integrin-Mediated Adaptation to Myocardial Ischemia
Authors: Henning Carina , Branopolski Anna , Follert Paula , Lewandowska Oksana , Ayhan Aysel , Benkhoff Marcel , Flögel Ulrich , Kelm Malte , Heiss Christian , Lammert Eckhard 
Published: January 2021

Abstract
Background Short episodes of myocardial ischemia can protect from myocardial infarction. However, the role of endothelial β1 integrin in these cardioprotective ischemic events is largely unknown.
Objective In this study we investigated whether endothelial β1 integrin is required for cardiac adaptation to ischemia and protection from myocardial infarction.
Methods Here we introduced transient and permanent left anterior descending artery (LAD) occlusions in mice. We inhibited β1 integrin by intravenous injection of function-blocking antibodies and tamoxifen-induced endothelial cell (EC)-specific deletion of Itgb1. Furthermore, human ITGB1 was silenced in primary human coronary artery ECs using small interfering RNA. We analyzed the numbers of proliferating ECs and arterioles by immunohistochemistry, determined infarct size by magnetic resonance imaging (MRI) and triphenyl tetrazolium chloride staining, and analyzed cardiac function by MRI and echocardiography.
Results Transient LAD occlusions were found to increase EC proliferation and arteriole formation in the entire myocardium. These effects required β1 integrin on ECs, except for arteriole formation in the ischemic part of the myocardium. Furthermore, this integrin subunit was also relevant for basal and mechanically induced proliferation of human coronary artery ECs. Notably, β1 integrin was needed for cardioprotection induced by transient LAD occlusions, and the absence of endothelial β1 integrin resulted in impaired growth of blood vessels into the infarcted myocardium and reduced cardiac function after permanent LAD occlusion.
Conclusion We showed that endothelial β1 integrin is required for adaptation of the heart to cardiac ischemia and protection from myocardial infarction.
Hermitian-Yang-Mills approach to the conjecture of Griffiths on the positivity of ample vector bundles
Authors: Demailly J.-P. 
Published: January 2021

AbstractGiven a vector bundle of arbitrary rank with ample determinant line bundle on a projective manifold, we propose a new elliptic system of differential equations of Hermitian-Yang-Mills type for the curvature tensor. The system is designed so that solutions provide Hermitian metrics with positive curvature in the sense of Griffiths — and even in the dual Nakano sense. As a consequence, if an existence result could be obtained for every ample vector bundle, the Griffiths conjecture on the equivalence between ampleness and positivity of vector bundles would be settled.Bibliography: 15 titles.
Effective electrical resistivity in a square array of oriented square inclusions
Authors: Guralnik Benny , Hansen Ole , Henrichsen Henrik H , Caridad José M , Wei Wilson , Hansen Mikkel F , Nielsen Peter F , Petersen Dirch H 
Published: January 2021

Abstract
The continuing miniaturization of optoelectronic devices, alongside the rise of electromagnetic metamaterials, poses an ongoing challenge to nanofabrication. With the increasing impracticality of quality control at a single-feature (-device) resolution, there is an increasing demand for array-based metrologies, where compliance to specifications can be monitored via signals arising from a multitude of features (devices). To this end, a square grid with quadratic sub-features is amongst the more common designs in nanotechnology (e.g. nanofishnets, nanoholes, nanopyramids, μLED arrays etc). The electrical resistivity of such a quadratic grid may be essential to its functionality; it can also be used to characterize the critical dimensions of the periodic features. While the problem of the effective electrical resistivity ρ
eff of a thin sheet with resistivity ρ
1, hosting a doubly-periodic array of oriented square inclusions with resistivity ρ
2, has been treated before (Obnosov 1999 SIAM J. Appl. Math.
59 1267–87), a closed-form solution has been found for only one case, where the inclusion occupies c = 1/4 of the unit cell. Here we combine first-principle approximations, numerical modeling, and mathematical analysis to generalize ρ
eff for an arbitrary inclusion size (0 < c < 1). We find that in the range 0.01 ≤ c ≤ 0.99, ρ
eff may be approximated (to within <0.3% error with respect to finite element simulations) by:

ρ

e
f
f

=

ρ

1

α

(
c
)

−

1
−

ρ

2

/

ρ

1

1
+

ρ

2

/

ρ

1

α

(
c
)

+

1
−

ρ

2

/

ρ

1

1
+

ρ

2

/

ρ

1

c
·
α

(
c
)

,

α

(
c
)

=
1
+

0.9707

0.9193
+

c

1
−
c

2.1261

0.4671

.

whereby at the limiting cases of c → 0 and c → 1, α approaches asymptotic values of α = 2.039 and α = 1/c − 1, respectively. The applicability of the approximation to considerably more complex structures, such as recursively-nested inclusions and/or nonplanar topologies, is demonstrated and discussed. While certainly not limited to, the theory is examined from within the scope of micro four-point probe (M4PP) metrology, which currently lacks data reduction schemes for periodic materials whose cell is smaller than the typical μm-scale M4PP footprint.
Micromechanical modeling approach with simplified boundary conditions to compute electromechanical properties of architected piezoelectric composites
Authors: Khan Kamran A , Al Hajeri Falah , Khan Muhammad Ali 
Published: January 2021

Abstract
Architected piezoelectric composites (PCs) have recently gained interest in designing transducers and nondestructive testing devices. The current analytical modeling approach cannot be readily applied to design architected periodic PCs exhibiting elastic anisotropy and piezoelectric activity. This study presents a micromechanical (MM)-model based finite element (FE) modeling framework to predict the electromechanical properties (EMPs) of the architected PCs. As an example, the microstructure with one-dimensional (1–3 PCs) connectivity is considered with different cross-sections of fibers. 3D FE models are developed. The intrinsic symmetry of architected composite is used to derive boundary conditions (BCs) equivalent to periodic BCs (PBCs). The proposed approach is simple and eliminates the need for a tedious mesh generation process on opposite boundary faces on the MM model of architected PCs. The EMPs of 1–3 PCs calculated from the proposed micromechanics-FE models were compared with those obtained from analytical solutions (i.e. based on micromechanics theories), and FE homogenization (i.e. obtained by employing the PBCs available in the literature). A quite good agreement between the proposed modeling approach and the ones obtained using the analytical model was observed. However, an excellent agreement is observed with the MM results that employed PBCs. Hence, we have concluded that the proposed MM modeling approach is equivalent to MM models that employed PBCs. The computed enhanced effective elastic, piezoelectric, and dielectric properties and corresponding figure of merit revealed that 1–3 PCs are suitable in transducer applications.
Fabrication, characterization and analytical modeling of gradient auxetic closed cell foams
Authors: Duncan Olly , Alderson Andrew , Allen Tom 
Published: January 2021

AbstractAuxetic (negative Poisson’s ratio) and gradient open cell foams have shown promise for their conformability and high impact energy absorption—useful in applications like protective equipment, footwear and prosthetics. Recent methods fabricated auxetic closed cell foam by steaming conventional closed cell foam. Methods developed herein control the cell structure of auxetic closed cell foam, to produce novel intentionally anisotropic and gradient auxetic closed cell foam. Pins passed through the foam constrained or stretched regions during steaming to further modify cell structure, and impart gradients in cell structure, Young’s modulus and Poisson’s ratios. Fabricated foams had Poisson’s ratios between 1 and −1. Imparted Young’s moduli of 1–12 MPa were similar to foams used in footwear, prosthesis, helmets and other impact protection. The effect of changes to cell structure on Young’s moduli and Poisson’s ratio are explained by combining analytical models of auxetic open cell and conventional closed cell foam.
Timber moisture detection using wavelet packet decomposition and convolutional neural network
Authors: Yuan Cheng , Zhang Jicheng , Chen Lin , Xu Jia , Kong Qingzhao 
Published: January 2021

Abstract
As timber structures are vulnerable to degradation due to the tendency to trap moisture, the present study proposed a new percussion-based method to replace the existing constant contact between structures and sensors. A total of two approaches have been proposed to automated detect the moisture content (MC) of timber: (a) the random forest classifier (machine learning-based) was employed to classify the wavelet packet decomposition (WPD) features extracted from excitation-induced sound signals (WPD + RF); and (b) the 2D-CNN framework (deep learning-based) was employed to classify the Mel frequency cepstral coefficient (MFCC) features extracted from excitation-induced sound signals (MFCC + 2DCNN). The proposed automatic detection methods are covered from 1D time-domain signal classification to 2D image classification. To verify the effectiveness of both two approaches, an experimental study was conducted. The MC of two types of timber specimens (i.e. softwood and hardwood) was gradually increased from 0% to 60% with 10% increments. The change of MC of timber material caused different material properties, resulting in a measurable differential in forced vibration among the various specimens used. The results demonstrated that MFCC + 2DCC outperformed the RF + WPD in MC classification of timber material. Overall, the percussion-based method proposed in this study can provide an outstanding classification performance.
A new self-adaptive magneto-rheological damper for washing machines
Authors: Bui Quoc-Duy , Nguyen Quoc Hung , Hoang Long-Vuong , Mai Duc-Dai 
Published: January 2021

Abstract
This paper deals with a novel self-adaptive magneto-rheological (MR) damper in shear-mode which can control vibrations of washing machines more effectively than commercial passive dampers. The damper comprises a shaft and a housing sliding relatively on a gap filled with MR fluid (MRF). Permanent magnets are fastened on the two shaft ends leaving a middle plain shaft part. The greater the vibration the more magnets enter the MRF region, which results in a higher damping force to attenuate the vibration. Compared with conventional and self-powered MR dampers, the proposed damper has much lower cost for commercial ability since it can itself adjust damping levels corresponding to external vibratory excitations without any control equipment or power unit. It also has simple and compact structure (no magnetic coils), which facilitate manufacturing and maintenance. Another remarkableness of the proposed MR damper is its displacement-dependent damping characteristic which extremely conforms to operation of washing machines. After an overview of the state of the art of vibration control for washing machines, the proposed self-adaptive MR damper is configured. Major geometry of the proposed damper is then optimized to satisfy production cost, size, installation space, off-state force and desired damping force. Based on the obtained optimal solutions, detailed design of the damper is performed and two damper prototypes are manufactured. The dampers are then installed in a prototype washing machine for testing and their experimental performances are compared with conventional passive dampers.
Damage localization in fiberglass-reinforced composites using laser induced graphene
Authors: Groo LoriAnne , Nasser Jalal , Inman Daniel , Sodano Henry 
Published: January 2021

Abstract
Current in situ piezoresistive damage detection techniques for fiberglass-reinforced composites are limited in widespread application as they require complex processing techniques which inhibit the scalability of the methods. To eradicate such challenges and expand the use of piezoresistive monitoring of fiberglass composites, this work utilizes a simple, scalable process to coat electrically insulating commercial fiberglass prepreg with piezoresistive laser induced graphene (LIG) for the detection and localization of damage. Recently, LIG has attracted substantial research attention due to the simplicity of the methodology and the piezoresistance of the LIG. Here, the LIG is transfer printed onto commercial fiberglass prepreg which is subsequently used to localize damage in all three dimensions of the resultant fiberglass-reinforced composites while also maintaining the structural properties of the composites. A combination of in situ and ex-situ resistance measurements are used to accomplish this objective: First, in situ measurements are used to determine the relative location of damage in one-dimension under tensile loading. Subsequently, separate in situ measurements are used to locate damage through the thickness under flexural loading. Finally, ex-situ methods are used to calculate the two-dimensional location of a hole in a plate. The LIG is found to reliably and accurately localize the damage to the composite in each case thus demonstrating for the first time that transfer printed LIG enables self-sensing of damage location in fiberglass composites. The result of this work is thus a multifunctional material capable of locating damage in all three-dimensions which is notably fabricated using commercial materials and scalable methodology.
Electron choreography at the attosecond time scale
Authors: Unzicker B , Vaughan J , Burrows S , Tatum B , Arthur D , Olsson T , Jain S , Hart T , Stringer P , Laurent G M 
Published: January 2021

Abstract
In this work, we report on coherent control of electron dynamics in atoms via attosecond pulse-shaping. We show that the photoelectron emission from argon gas produced by absorption of an attosecond pulse train (APT) made of odd and even harmonics can be manipulated along the direction of polarization of the light by tuning the spectral components (amplitude and phase) of the pulse. In addition, we show that APTs produced with a two-color (400- plus 800 nm) femtosecond driving field exhibit high temporal tunability, which is optimized for an intensity ratio between the two colors in the range of 0.1 to 5%.
The analysis of coherent phenomena for both linear and non-linear interactions in a four-level ladder (Ξ)-type configuration using density matrix formalism in dressed state representation
Authors: Laskar Rejjak , Hossain Md Mabud , Saha Jayanta K 
Published: January 2021

Abstract
In this paper, we present a theoretical study of Autler-Townes (AT) splitting, electromagnetically induced transparency (EIT) and electromagnetically induced absorption (EIA) phenomena in a four-level ladder (Ξ)-type configuration formed by two coupling and one probe laser fields using density matrix formalism in dressed state representation (DSR). The DSR is followed by the analytical solution of the optical Bloch equations (OBEs) under density matrix formalism in bare state representation (BSR). The density matrix elements are presented in both linear and non-linear interaction regimes under DSR. The concept of transfer of population (TOP) mechanism has been shown by calculating the different transition probabilities in DSR. It has been found that the population in a particular dressed state is greatly enhanced by increasing the strength of coupling field and played a key role to manipulate the induced coherence between different energy levels. The present theoretical model of DSR offers an excellent interpretation of the formation of EIT, EIA and conversion from EIT to EIA in both linear and third order non-linear probe absorption profiles. Besides, the dispersion profiles in both linear and non-linear interaction regimes have also been studied and the conversion of normal to anomalous dispersion profile which drastically modifies the optical responses of the medium has been discussed. We have found that the amplitudes of the coherent signals are more sensitive to the third order non-linear interaction compared to first order linear interaction.
Beta-tricalcium phosphate promotes osteogenic differentiation of bone marrow-derived mesenchymal stem cells through macrophages
Authors: Zheng Mengting , Weng Mengjia , Zhang Xiaoyu , Li Ruomei , Tong Qian , Chen Zhenqi 
Published: January 2021

Abstract
Macrophages are vital regulators of skeletal remodeling and osseous repair. Beta-tricalcium phosphate (β-TCP) is a synthetic ceramic biomaterial that has shown promise as bone substitute. However, whether and how β-TCP affects osteogenesis-related responses of macrophages has rarely been studied. The aims of this study were to explore (a) the effects of β-TCP on osteogenic differentiation of bone marrow-derived mesenchymal stem cells (BMSCs) co-cultured with macrophages and (b) on macrophage polarization as well as macrophage gene and protein expression profiles. BMSC osteogenic differentiation capacity in vitro was enhanced in β-TCP-induced co-cultured BMSCs compared to that in BMSC monocultures. We also found that macrophages induced with 25 mg ml−1
β-TCP extract had more significant immune responses and switched to the M2 phenotype. Expression levels of the Wnt signaling pathway modulators wingless-type MMTV integration site family, member 6 (WNT6) and Wnt inhibitory factor 1 (WIF1) were upregulated and downregulated, respectively, in macrophages treated with β-TCP extract. Our findings suggest that β-TCP enhances osteogenic differentiation of BMSCs by inducing macrophage polarization and by regulating the Wnt signaling pathway, thereby highlighting its therapeutic potential for bone healing through osteoimmunomodulatory properties.
Preparation, characterization, and in vitro and in vivo biocompatibility evaluation of polymer (amino acid and glycolic acid)/hydroxyapatite composite for bone repair
Authors: Fan Xiaoxia , Li Li , Zhu Hui , Yan Lin , Zhu Sudi , Yan Yonggang 
Published: January 2021

Abstract
A composite of hydroxyapatite (HA) and polymers prepared from amino acids and glycolic acid (PAG) was synthesized using an in situ melting polycondensation method. The in vitro degradability and bioactivity of the composite were evaluated, as well as its in vitro and in vivo biocompatibility based on subcutaneous and osseous implantation of samples in New Zealand white rabbits for 8 weeks. The results showed that the PAG/HA composite had higher degradability than PAG and showed a typical apatite morphology after immersion in simulated body fluid for 5 d. Both the PAG/HA composite and PAG alone showed excellent in vitro biocompatibility. In the rabbit model, PAG/HA composite could induce formation of new bone tissue after 4 weeks implantation, mainly owing to the excellent in vivo bioactivity of the implant. These results suggest that PAG/HA composites have the potential to guide bone regeneration and could be used as biodegradable biomaterials for bone repair.
Monitoring and moderating extreme indoor temperatures in low-income urban communities
Authors: Wilby R L , Kasei R , Gough K V , Amankwaa E F , Abarike M , Anderson N J , Codjoe S N A , Griffiths P , Kaba C , Abdullah K , Kayaga S , Matthews T , Mensah P , Murphy C , Yankson P W K 
Published: January 2021

Abstract
Climate change presents significant threats to human health, especially for low-income urban communities in the Global South. Despite numerous studies of heat stress, surprisingly little is known about the temperatures actually encountered by people in their homes, or the benefits of affordable adaptations. This paper examines indoor air temperature measurements gathered from 47 living rooms within eight low-income communities of Accra and Tamale, Ghana. Using multiple temperature indices and a tiered analysis, we evaluate indoor temperature variations linked to roof type, ceiling insulation, presence of fans, and tree shade, for different housing types and locations. Our data reveal indoor temperatures in the range 22.4 °C to 45.9 °C for Accra, and 22.2 °C to 43.0 °C in Tamale. Using dummy regression analysis, we find that tree shade reduces the number of very hot days (>40 °C) and nights (>30 °C) by about 12 and 15 d per year, respectively. Building materials also strongly moderate indoor temperatures but in opposing ways: rooms with traditional mud walls and thatch roofs are on average 4.5 °C cooler than rooms in concrete block houses with uninsulated metal roofs during the day but are 1.5 °C warmer at night; rooms with ceiling insulation are on average 6.9 °C cooler in the day but 1.4 °C warmer at night. We conclude that sub-daily data are necessary for reporting extreme indoor temperatures, and that trade-offs between minimum and maximum temperatures require interventions to be assessed carefully before attempting to counter extreme heat inside homes.
Arctic tourism development: comparative study of Murmansk region and Norway
Authors: Kikkas Kseniia N , Sosnina Maria N , Rubtsova Anna V 
Published: January 2021

Abstract
The study focuses on tourism development in the Arctic on the example of Murmansk Region, Russia, and Norway. The study quantified the tourism industry in Murmansk Region and Norway, proposed a tourism development model in the form of a system of econometric equations, estimated prospects for the Arctic tourism in Norway using the above-mentioned model, analysed positive developments in Norwegian tourism, and presented recommendations aimed at improving Arctic tourism in Murmansk Region, Russia.