bluuebunny/crossref_metadata_2025 huggingface dataset:
Cancer Theranostics: Bridging Conventional and Nano-photodynamic Therapy
Authors: Gananathan Poorani , Chakraborty Anirban , Karunasagar Indrani
Published: April 2020

Cancer is of various kinds, so are the treatment modalities. Worldwide, cancer is the second leading cause of death, accounting for a whopping 9.6 million deaths in 2018. Globally, approximately one in six deaths is attributed to cancer. Photodynamic therapy (PDT) is a therapeutic strategy for the treatment of superficial lesions, warts, Barrett’s esophagus, premalignant lesions, malignant tumors, and ophthalmic diseases. The literature on PDT is approximately one-third of that in radiation therapy, yet the clinical implementation of PDT in cancer is relatively less. Despite substantial research, the clinical application of photodynamic strategy in cancer therapy is still in its infancy with only a limited number of case studies reported so far. The limitations of the photosensitizer and the shallow depth of penetration of light source are the key technical impediments. However, the use of nanomedicine in PDT can overcome these obstacles. Thus, it is necessary to gain knowledge on how nanomaterials can be merged with PDT and how it can be utilized in cancer theranostics. In this article, the focus is to understand how PDT works and how it can be utilized in improving the sensitivity of the existing diagnostic and therapeutic techniques. The article also addresses the current challenges for PDT and the future prospects of this technique, particularly in the area of diagnosis and treatment of cancer.
Ultraviolet solar flare signatures in the framework of complex network
Authors: Lotfi Nastaran , Javaherian Mohsen , Kaki Bardia , Darooneh Amir Hossein , Safari Hossein
Published: April 2020

Studying natural phenomena via the complex network approach makes it possible to quantify the time-evolving structures with too many elements and achieve a deeper understanding of interactions among the components of a system. In this sense, solar flare as a complex system with the chaotic behavior could be better characterized by the network parameters. Here, we employed an unsupervised network-based method to recognize the position and occurrence time of the solar flares by using the ultraviolet emission (1600 Å) recorded by the Atmospheric Imaging Assembly on board Solar Dynamics Observatory. Three different regions, the flaring active regions, the non-flaring active regions, and the quiet-Sun regions, were considered to study the variations of the network parameters in the presence and absence of flaring phases in various datasets over time intervals of several hours. The whole parts of the selected datasets were partitioned into sub-windows to construct networks based on computing the Pearson correlation between time series of the region of interest and intensities. Analyzing the network parameters such as the clustering coefficient, degree centrality, characteristic length, and PageRank verified that flare triggering has an influence on the network parameters around the flare occurrence time and close to the location of flaring. It was found that the values of the clustering coefficient and characteristic length approach those obtained for the corresponding random network in the flaring phase. These findings could be used for detecting the occurrence times and locations of the region at ultraviolet images.
Heterogeneously flagellated microswimmer behavior in viscous fluids
Authors: Rogowski Louis William , Oxner Micah , Tang Jiannan , Kim Min Jun
Published: April 2020

An analysis of heterogeneously flagellated microswimmers inside viscous fluids is presented. Flagella harvested from Salmonella typhimurium were isolated, repolymerized, and functionalized to have biotin at their ends, allowing for chemical attachment along the surfaces of avidin-coated microparticles. Assembled microswimmers were rotated under incremental magnetic field frequencies, in saline and methylcellulose solutions, to baseline their velocity responses. A mean square displacement analysis revealed that rotating microswimmers exhibited anomalous diffusive behavior at small time scales in each fluid and had increased diffusivity compared with the non-rotating cases. Flagellated microswimmers had decreased diffusivity when compared with non-flagellated microparticles in Brownian conditions. Microswimmers were demonstrated to perform selected trajectories under proportional feedback control with reasonable accuracy. Finally, microswimmer propulsion was shown to be heavily influenced by the handedness of the rotating magnetic fields, with frequency induced reversals of swimming direction observed under clockwise rotation; this effect was determined to be the result of flagellar bundling and unbundling.
Topotactic transformation in SrFeO3−
δ
triggered by low-dose Ga+ focused ion irradiation
Authors: Ferreiro-Vila Elías , Bugallo David , Magén César , Rivadulla Francisco , De Teresa José María
Published: April 2020

We introduce a single-step lithography process based on Ga+-focused ion beam (FIB) irradiation to trigger a topotactic transformation on SrFeO3−δ thin films, from the perovskite to the brownmillerite (BM) crystal structure. The crystallographic transformation is triggered by preferential oxygen sputtering by Ga+-FIB irradiation, which favors the formation of the SrFeO2.5 BM phase. The transformation has been verified through micro-Raman spectroscopy on thin films subjected to Ga+-FIB irradiation under 5 kV and 30 kV. Inducing crystallographic transformations by FIB in a single-step process (without the need of resists), at a very high speed (low Ga+ doses are required, in the range of 1015 ions/cm2), with very high spatial resolution (limited by the ion beam spot, of a few square nanometers) and with potential for upscaling using broad Ga+ beams, this approach represents a significant forward step over previous methods using multistep lithographic or electrochemical procedures. All these virtues make this process appealing to develop applications based not only on SrFeO3−δ thin films but also on other oxide films harnessing topotactic transformations.
Design of terahertz-wave Doppler interferometric velocimetry for detonation physics
Authors: Zhai Zhao-Hui , Sun Chang-Lin , Liu Qiao , Guo Liu-Wei , Liu Yu-Si , Zhang Xu , Wang De-Tian , Meng Kun , Li Jiang , Du Liang-Hui , Liu Shou-Xian , Zhong Sen-Cheng , Zhu Li-Guo
Published: April 2020

The diagnosis of the initiation and growth of detonation in high explosives (HEs) is important in detonation physics. We designed and experimentally demonstrated a non-invasive high-precision free-space terahertz-wave Doppler interferometric velocimetry (TDV) design for diagnosing the transient detonation processes in HEs. The system can non-intrusively record the propagation of the shock/detonation wavefront inside HEs continuously and measure key detonation parameters (position/displacement, detonation velocity, etc.). A detailed quasi-optical design for TDV is discussed. The terahertz penetration ability and the refractive index of representative HEs are presented in the frequency range of 0.2–1.4 THz. Additionally, a typical shock-to-detonation transition of an insensitive high explosive was studied using a prototype 0.212 THz TDV system, which demonstrated the high precision of displacement measurements made using I/Q demodulation. Furthermore, the performance of the TDV technique is discussed. TDV may enable non-invasive and high-precision diagnostics for detonation and shockwave physics.
633-nm InGaN-based red LEDs grown on thick underlying GaN layers with reduced in-plane residual stress
Authors: Iida Daisuke , Zhuang Zhe , Kirilenko Pavel , Velazquez-Rizo Martin , Najmi Mohammed A. , Ohkawa Kazuhiro
Published: April 2020

This work investigates the influence of residual stress on the performance of InGaN-based red light-emitting diodes (LEDs) by changing the thickness of the underlying n-GaN layers. The residual in-plane stress in the LED structure depends on the thickness of the underlying layer. Decreased residual in-plane stress resulting from the increased thickness of the underlying n-GaN layers improves the crystalline quality of the InGaN active region by allowing for a higher growth temperature. The electroluminescence intensity of the InGaN-based red LEDs is increased by a factor of 1.3 when the thickness of the underlying n-GaN layer is increased from 2 to 8 μm. Using 8-μm-thick underlying n-GaN layers, 633-nm-wavelength red LEDs are realized with a light-output power of 0.64 mW and an external quantum efficiency of 1.6% at 20 mA. The improved external quantum efficiency of the LEDs can be attributed to the lower residual in-plane stress in the underlying GaN layers.
Spectrally selective photodetection in the near-infrared with a gold grating-based hot electron structure
Authors: Xiao Hongbin , Lo Shu-Cheng , Tai Yi-Hsin , Ho Ya-Lun , Clark J. Kenji , Wei Pei-Kuen , Delaunay Jean-Jacques
Published: April 2020

A Si channel-separated interdigitated Au grating structure is demonstrated to achieve spectrally selective photodetection in the C-band (1530–1565 nm) in this work. The measured full width at half-maximum of the structure reaches as narrow as 23 nm, and the measured responsivity reaches 804 nA/mW at the resonant wavelength of 1550 nm and the bias voltage of 0.08 V. The responsivity represents a large variation of 59% when the light wavelength is varied by only 20 nm (from 1550 to 1530 nm). A theoretical model is also performed to quantify the photocurrent response in terms of the optical and electrical properties of the structure. The strongly resonant and narrowband photocurrent response and readily tunable resonant wavelength not only enable the structure to achieve spectrally selective photodetection in the near-infrared region but also make it amenable to the application of sensing devices, imaging devices, and other optoelectronic devices working in the sub-bandgap regime of semiconductor materials.
High pressure dielectric study of N-ethylacetamide
Authors: Rams-Baron Marzena , Jedrzejowska Agnieszka , Paluch Marian
Published: April 2020

As a step toward better understanding of the Debye-like response in N-ethylacetamide (NEA), we performed the broadband dielectric measurement of NEA under high pressure (up to p = 968 MPa). Currently, the prevailing opinion of an intense Debye-like relaxation in N-mono-substituted amides is that it originates from the slow dynamics of hydrogen-bonded supramolecular structures analogous to the Debye-like peak observed in monohydroxy alcohols. However, our results revealed that the high pressure behavior of NEA is different from that of monohydroxy alcohols. In contrast to monohydroxy alcohols, we found that the shape of dielectric loss spectra of NEA was unaffected by compression. In the light of these results, further critical discussion is required in order to improve our understanding of relaxation properties of NEA.
Systematic description of molecular deformations with Cremer–Pople puckering and deformation coordinates utilizing analytic derivatives: Applied to cycloheptane, cyclooctane, and cyclo[18]carbon
Authors: Zou Wenli , Tao Yunwen , Kraka Elfi
Published: April 2020

The conformational properties of ring compounds such as cycloalkanes determine to a large extent their stability and reactivity. Therefore, the investigation of conformational processes such as ring inversion and/or ring pseudorotation has attracted a lot of attention over the past decades. An in-depth conformational analysis of ring compounds requires mapping the relevant parts of the conformational energy surface at stationary and also at non-stationary points. However, the latter is not feasible by a description of the ring with Cartesian or internal coordinates. We provide in this work, a solution to this problem by introducing a new coordinate system based on the Cremer–Pople puckering and deformation coordinates. Furthermore, analytic first- and second-order derivatives of puckering and deformation coordinates, i.e., B-matrices and D-tensors, were developed simplifying geometry optimization and frequency calculations. The new coordinate system is applied to map the potential energy surfaces and reaction paths of cycloheptane (C7H14), cyclooctane (C8H16), and cyclo[18]carbon (C18) at the quantum chemical level and to determine for the first time all stationary points of these ring compounds in a systematic way.
Structural characterization of the NO(X2Π)–N2O complex with mid-infrared laser absorption spectroscopy and quantum chemical calculations
Authors: Liu Zhuang , Li Xiang , Ge Murong , Zheng Rui , Duan Chuanxi
Published: April 2020

Both positive and negative ions of N3O2 have been observed in various experiments. The neutral N3O2 was predicted to exist either as a weakly bound NO·N2O complex or a covalent molecule. The rovibrational spectrum of the NO(X2Π)–N2O complex has been measured for the first time in the 5.3 µm region using distributed quantum cascade lasers to probe the direct absorption in a slit-jet supersonic expansion. The observed spectrum is analyzed with a semi-rigid asymmetric rotor Hamiltonian for a planar open-shell complex, giving a bent geometry with an a-axis–NO angle of about 21.9°. The vibrationally averaged 2A′–2A″ energy separation is determined to be ε = 144.56(95) cm−1 for the ground state, indicating that the electronic orbital angular momentum is partially quenched upon complexation. Geometry optimizations of the complex restricted to a planar configuration at the RCCSD(T)/aug-cc-pVTZ level of theory show that the 2A″ state is more stable than the 2A′ state by about 110 cm−1 and the N atom of NO points to the central N atom of N2O at the minimum of the 2A″ state.
Stress-localization induced toughening in CNT–silica nanocomposites
Authors: Hao Tengyuan , Hossain Zubaer M.
Published: April 2020

Applying a combination of atomistic and continuum scale simulations, we show that stress-localization forms the fundamental basis for toughening in “carbon nanotube reinforced amorphous silica” (CNT−aSiO2). Depending on the cohesive strength of the interface, a propagating crack renders three distinct types of failure conditions: (i) with stronger cohesive interactions both silica and nanotube undergo catastrophic failure, (ii) with moderate cohesive interactions the nanotube debonds from the matrix and undergoes severe mechanical deformation but fracture remains in the matrix, and (iii) with lower cohesive strengths the nanotube debonds from the matrix easily and allows quicker failure of the matrix, compared to the previous two failure conditions. For either of the cases, continued propagation of the crack requires renucleation at the opposite side of the nanotube. However, the renucleation criteria are mostly unaffected by the strength of interfacial interactions. Also, the effective toughness of the nanocomposite increases nonlinearly with increasing interfacial strength and the maximum possible toughness enhancement is strictly controlled by the strength of elastic interactions between the nanotube and the matrix. The overall toughening behavior of the nanocomposite is governed primarily by stress-localization at the nanotube–silica intersections along the projected crack path direction in the composite. The observations highlight the dramatic role of site-selective interatomic interactions that can affect the macroscopic mechanical behavior of the nanocomposite substantially.
Thermoelectric properties of aperiodic gated graphene superlattices
Authors: Kim Meeri
Published: April 2020

Aperiodicity may provide a way to enhance thermoelectric properties in gated graphene superlattices.
Magnetic solid-phase extraction of phthalate esters from environmental water samples using fibrous phenyl-functionalized Fe3O4@SiO2@KCC-1
Authors: Zhou Xue-zheng , Yan Xiang-yang , Zhu Ling , Ma Ming , Dai Ya , Wang Chang-guo , Zhu Li-jun , Yu Ke-jie , Liu Shao-min
Published: April 2020

A new kind of phenyl-functionalized magnetic fibrous mesoporous silica (Fe3O4@SiO2@KCC-1-phenyl) was prepared by copolymerization as an efficient adsorbent for the magnetic extraction of phthalate esters from environmental water samples. The obtained Fe3O4@SiO2@KCC-1-phenyl showed monodisperse fibrous spherical morphology, fairly strong magnetic response (29 emu/g), and an abundant π-electron system, which allowed rapid isolation of the Fe3O4@SiO2@KCC-1-phenyl from solutions upon applying an appropriate magnetic field. Several variables that affect the extraction efficiency of the analytes, including the type of the elution solvent, amount of adsorbent, extraction time and reusability, were investigated and optimized. Under optimum conditions, the Fe3O4@SiO2@KCC-1-phenyl was used for the extraction of four phthalate esters from environmental water samples followed by high-performance liquid chromatographic analysis. Validation experiments indicated that the developed method presented good linearity (0.1–20 ng/mL), low limit of detection (7.5–29 µg/L, S/N =3). The proposed method was applied to the determination of phthalate esters in different real water samples, with relative recoveries of 93%−103.4% and relative standard deviation of 0.8%–8.3%.
In situ one-pot fabrication of MoO3−x clusters modified polymer carbon nitride for enhanced photocatalytic hydrogen evolution
Authors: Qi Rong-jie , Liu Jun-ying , Wei Zhi-dong , Guo Wei-qi , Jiang Zhi , Shangguan Wen-feng
Published: April 2020

Developing low-cost and high-efficient noble-metal-free cocatalysts has been a challenge to achieve economic hydrogen production. In this work, molybdenum oxides (MoO3−x) were in situ loaded on polymer carbon nitride (PCN) via a simple one-pot impregnation-calcination approach. Different from post-impregnation method, intimate coupling interface between high-dispersed ultra-small MoO3−x nanocrystal and PCN was successfully formed during the in situ growth process. The MoO3−x-PCN-X (X=1, 2, 3, 4) photocatalyst without noble platinum (Pt) finally exhibited enhanced photocatalytic hydrogen performance under visible light irradiation (λ>420 nm), with the highest hydrogen evolution rate of 15.6 µmol/h, which was more than 3 times that of bulk PCN. Detailed structure-performance revealed that such improvement in visible-light hydrogen production activity originated from the intimate interfacial interaction between high-dispersed ultra-small MoO3−x nanocrystal and polymer carbon nitride as well as efficient charge carriers transfer brought by Schottky junction formed.
Graphene-passivated nickel as an efficient hole-injecting electrode for large area organic semiconductor devices
Authors: Di Nuzzo Daniele , Mizuta Ryo , Nakanishi Kenichi , Martin Marie-Blandine , Aria Adrianus I. , Weatherup Robert , Friend Richard H. , Hofmann Stephan , Alexander-Webber Jack
Published: April 2020

Efficient injection of charge from metal electrodes into semiconductors is of paramount importance to obtain high performance optoelectronic devices. The quality of the interface between the electrode and the semiconductor must, therefore, be carefully controlled. The case of organic semiconductors presents specific problems: ambient deposition techniques, such as solution processing, restrict the choice of electrodes to those not prone to oxidation, limiting potential applications. Additionally, damage to the semiconductor in sputter coating or high temperature thermal evaporation poses an obstacle to the use of many device-relevant metals as top electrodes in vertical metal–semiconductor–metal structures, making it preferable to use them as bottom electrodes. Here, we propose a possible solution to these problems by implementing graphene-passivated nickel as an air stable bottom electrode in vertical devices comprising organic semiconductors. We use these passivated layers as hole-injecting bottom electrodes, and we show that efficient charge injection can be achieved into standard organic semiconducting polymers, owing to an oxide free nickel/graphene/polymer interface. Crucially, we fabricate our electrodes with low roughness, which, in turn, allows us to produce large area devices (of the order of millimeter squares) without electrical shorts occurring. Our results make these graphene-passivated ferromagnetic electrodes a promising approach for large area organic optoelectronic and spintronic devices.
Numerical study of roundness effect on flow around a circular cylinder
Authors: Wang Ran , Cheng Shaohong , Ting David S.-K.
Published: April 2020

Imperfectly round bridge stay cable cross section is speculated to be a key factor for wind-induced large-amplitude cable vibrations observed on site. A delayed detached eddy simulation implemented in Open source Field Operation and Manipulation is used to investigate the flow structure around and in the near-wake of an imperfectly round circular cylinder and the corresponding aerodynamic forces at a Reynolds number of 104 and an attack angle of 0° or 45°. With the increase in roundness imperfection, both monotonic and non-monotonic changes of the mean surface pressure and the wake velocity are found when the cylinder is normal to the flow. At an attack angle of 45° and when the roundness ratio is e/D = 4%, it is found that the geometric imperfection in the cross-sectional shape of the cylinder allows it to the retention of more axial flow in the proximity of the cylinder leeward surface due to a shorter recirculation length. The vortex formed by the intensified axial flow would interact with the conventional von Kármán vortex formation at a frequency a few times lower than that of the latter and lead to intermittently amplified transverse lift. This reveals that imperfect roundness in the cross section of a circular cylinder could be an excitation source of low frequency vibration. Thus, it provides evidence that this kind of geometric imperfection, which commonly exists in real stay cables, could contribute to the mechanisms that trigger large-amplitude or even divergent cable motion, such as dry inclined cable galloping on site.
Lateral silicon oxide/gold interfaces enhance the rate of electrochemical hydrogen evolution reaction in alkaline media
Authors: Maier Thomas L. , Golibrzuch Matthias , Mendisch Simon , Schindler Werner , Becherer Markus , Krischer Katharina
Published: April 2020

The production of solar hydrogen with a silicon based water splitting device is a promising future technology, and silicon-based metal–insulator–semiconductor (MIS) electrodes have been proposed as suitable architectures for efficient photocathodes based on the electronic properties of the MIS structures and the catalytic properties of the metals. In this paper, we demonstrate that the interfaces between the metal and oxide of laterally patterned MIS electrodes may strongly enhance the catalytic activity of the electrode compared to bulk metal surfaces. The employed electrodes consist of well-defined, large-area arrays of gold structures of various mesoscopic sizes embedded in a silicon oxide support on silicon. We demonstrate that the activity of these electrodes for hydrogen evolution reaction (HER) increases with an increase in gold/silicon oxide boundary length in both acidic and alkaline media, although the enhancement of the HER rate in alkaline electrolytes is considerably larger than in acidic electrolytes. Electrodes with the largest interfacial length of gold/silicon oxide exhibited a 10-times larger HER rate in alkaline electrolytes than those with the smallest interfacial length. The data suggest that at the metal/silicon oxide boundaries, alkaline HER is enhanced through a bifunctional mechanism, which we tentatively relate to the laterally structured electrode geometry and to positive charges present in silicon oxide: Both properties change locally the interfacial electric field at the gold/silicon oxide boundary, which, in turn, facilitates a faster transport of hydroxide ions away from the electrode/electrolyte interface in alkaline solution. This mechanism boosts the alkaline HER activity of p-type silicon based photoelectrodes close to their HER activity in acidic electrolytes.
Study of argon expulsion from the post-disruption runaway electron plateau following low-Z massive gas injection in DIII-D
Authors: Hollmann E. M. , Bykov I. , Eidietis N. W. , Herfindal J. L. , Lvovskiy A. , Moyer R. A. , Parks P. B. , Paz-Soldan C. , Pigarov A. Yu. , Rudakov D. L. , Shiraki D. , Watkins J.
Published: April 2020

A 1D radial diffusion model is developed to study the observed rapid expulsion of argon from the runaway electron plateau in the DIII-D tokamak following secondary massive low-Z (D2 or He) gas injection. The expulsion of argon is found to be caused by further cooling of the background plasma due to the added neutrals, accompanied by recombination of argon ions and the greatly increased outward radial transport rate of argon (now dominantly in neutral form) out of the runaway electron beam. After argon expulsion, power loss out of the runaway electron plateau is found to be dominated by neutral transport to the wall (rather than by radiation); this result resolves the power balance discrepancy highlighted in previous work on argon expulsion out of the runaway electron plateau.
Rotor interactional effects on aerodynamic and noise characteristics of a small multirotor unmanned aerial vehicle
Authors: Lee Hakjin , Lee Duck-Joo
Published: April 2020

Small scale unmanned aerial vehicles using multirotor propulsion systems have received considerable attention for a wide range of military and commercial applications in recent years. In the multirotor configuration, the rotor interaction phenomenon occurs severely because the rotors are located in close proximity to each other. Therefore, the separation distance between the adjacent rotor tips has a strong effect on the wake structures and flow fields, which consequently play an important role in determining the aerodynamic performance and noise level of the multirotor vehicle. In the present study, numerical simulations of a quadcopter under hover flight conditions are conducted to investigate the mutual rotor-to-rotor interactional effects on the aerodynamic performance, wake structures, and sound pressure level using the nonlinear vortex lattice method with the vortex particle method and acoustic analogy based on Farassat’s formulation 1A. Calculations for the multirotor configurations with different separation distances show that the average thrust force decreases significantly and force fluctuation is found to increase dramatically as the rotor spacing gets smaller. In addition, the wake geometry and induced flow structure behind the rotor tend to be radially dragged down toward the center of the vehicle due to the existence of the adjoining rotor, which consequently results in strong wake-to-wake interaction and the formation of asymmetric wake structures although the multirotor operates under the hovering condition. It is also observed that unsteady loading introduced by rotor interaction leads to a considerable increase in the sound pressure level, particularly the normal direction of the rotor plane.
Heat transfer enhancement and field synergy analysis of vacuum collector tube with inserted rotor
Authors: Geng Zhi , Gao Jifeng , Liu Haochen , Mo Ziyuan , Gu Yujiong , Li Renfeng , Zhang Lina , Wang Zhenghe , Liu Li , Zhang Xiang
Published: April 2020

Aiming at the large heat loss inside the traditional trough-type vacuum solar heat collecting tube, a new type of spiral three-blade rotor structure was designed and inserted into the inner tube side of the heat collecting tube. Based on the principle of fluid dynamics and field synergy, a mathematical model of the three governing equations of the fluid in the tube was established. Numerical simulations of the heat transfer and flow in the flow field in the two types of collector tubes with or without interpolated rotors were performed. Performance comparisons were made in terms of velocity field, pressure field, temperature field, and field synergy coupling ability. The results of the comprehensive evaluation index of heat transfer performance were finally given. The research shows that the PEC value continues to become larger with the increase in the inlet flow rate, from an initial value of 1.63 to a final value of 2.69. The heat transfer performance enhancement advantage of the new type vacuum heat collector tube is obviously greater than the disadvantage of flow resistance, and the comprehensive performance is better.
Long-wavelength infrared photovoltaic heterodyne receivers using patch-antenna quantum cascade detectors
Authors: Bigioli Azzurra , Armaroli Giovanni , Vasanelli Angela , Gacemi Djamal , Todorov Yanko , Palaferri Daniele , Li Lianhe , Davies A. Giles , Linfield Edmund H. , Sirtori Carlo
Published: April 2020

Quantum cascade detectors (QCDs) are unipolar infrared devices where the transport of the photoexcited carriers takes place through confined electronic states, without an applied bias. In this photovoltaic mode, the detector's noise is not dominated by a dark shot noise process, and therefore, performances are less degraded at high temperature with respect to photoconductive detectors. This work describes a 9 μm QCD embedded into a patch-antenna metamaterial, which operates with state-of-the-art performances. The metamaterial gathers photons on a collection area, Acoll, much larger than the geometrical area of the detector, improving the signal to noise ratio up to room temperature. The background-limited detectivity at 83 K is 5.5 × 1010 cm Hz1/2 W−1, while at room temperature, the responsivity is 50 mA/W at 0 V bias. A patch antenna QCD is an ideal receiver for a heterodyne detection setup, where a signal at a frequency of 1.4 GHz and T = 295 K is reported as demonstration of uncooled 9 μm photovoltaic receivers with a GHz electrical bandwidth. These findings guide the research toward uncooled IR quantum limited detection.
Using nanoresonators with robust chaos as hardware random number generators
Authors: Dantas W. G. , Rodrigues Lucas R. , Ujevic Sebastian , Gusso André
Published: April 2020

In this paper, we investigate theoretically the potential of a nanoelectromechanical suspended beam resonator excited by two-external frequencies as a hardware random number generator. This system exhibits robust chaos, which is usually required for practical applications of chaos. Taking advantage of the robust chaotic oscillations, we consider the beam position as a possible random variable and perform tests to check its randomness. The beam position collected at fixed time intervals is used to create a set of values that is a candidate for a random sequence of numbers. To determine how close to a random sequence this set is, we perform several known statistical tests of randomness. The performance of the random sequence in the simulation of two relevant physical problems, the random walk and the Ising model, is also investigated. An excellent overall performance of the system as a random number generator is obtained.
On-chip terahertz modulation and emission with integrated graphene junctions
Authors: Island Joshua O. , Kissin Peter , Schalch Jacob , Cui Xiaomeng , Ul Haque Sheikh Rubaiat , Potts Alex , Taniguchi Takashi , Watanabe Kenji , Averitt Richard D. , Young Andrea F.
Published: April 2020

The efficient modulation and control of ultrafast signals on-chip is of central importance in terahertz (THz) communications and a promising route toward sub-diffraction limit THz spectroscopy. Two-dimensional (2D) materials may provide a platform for these endeavors. We explore this potential, integrating high-quality graphene p–n junctions within two types of planar transmission line circuits to modulate and emit picosecond pulses. In a coplanar strip line geometry, we demonstrate the electrical modulation of THz signal transmission by 95%. In a Goubau waveguide geometry, we achieve complete gate-tunable control over THz emission from a photoexcited graphene junction. These studies inform the development of on-chip signal manipulation and highlight prospects for 2D materials in THz applications.
Palmitic acid-enriched fat supplementation alleviates negative production responses during early lactation of Holstein dairy cows
Authors: El-Zaiat Hani M. , Mohamed Dyaaeldin , Sallam Sobhy M.
Published: April 2020

Effects of rumen-protected fat (RPF) on suppressing the negative performance responses in early lactation period of Holstein dairy cows were investigated. Three hundred multiparous Holstein cows (647 ± 16 kg bodyweight and 90 days in milk (DIM)) were randomly housed into three free-stall barns (100 cows per barn) and assigned to the treatments for 90 days, as follows: (1) control (CTL) diet without RPF; (2) calcium salt of palm fatty acids (CaFA) 30 g/kg DM, and (3) fractionated fatty acids of palm oil (FFA) 25 g/kg DM. Cows were fed total mixed ration containing 580 g of concentrate and 420 g of roughage per kilogram DM. Cows fed FFA exhibited a higher (P < 0.05) DM intake and body condition score than did those fed CaFA or CTL diets respectively. Moreover, cows fed the FFA diet showed decreased (P < 0.05) changes to bodyweight at 30 DIM and to body condition score at 60 DIM and increased digestibility of ether extract and neutral detergent fibre. Blood concentrations of triglycerides, cholesterol and glucose were higher (P < 0.05) for cows fed FFA diet than for those fed the other diets, between 4 and 30 DIM, whereas concentrations of non-esterified fatty acids, β-hydroxybutyric acid and urine ketones were lower for cows fed RPF sources (P < 0.05). Relative to CTL diet, CaFA and FFA diets increased (P < 0.05) milk yield and milk fat content at 4–30 DIM. Feeding FFA improved feed efficiency by 8.9% (P = 0.006), between 31 and 60 DIM, compared with CaFA. Inclusion of a palmitic acid-enriched fat supplement in Holstein cow diet increased milk yield and fat content and mitigated the deleterious effects of metabolic disorders during the early lactation period.
Diets selected and growth of steers grazing buffel grass (Cenchrus ciliaris cv. Gayndah)–Centro (Centrosema brasilianum cv. Oolloo) pastures in a seasonally dry tropical environment
Authors: Dixon R. M. , Shotton P. , Mayer R.
Published: April 2020

Context
Liveweight (LW) gain of grazing cattle in the seasonally dry tropics is usually moderate during the wet season (WS) and declines to slow growth or LW loss during the dry season (DS). Cattle growth can often be improved by inclusion of herbaceous legumes into pastures to improve their nutritional quality.

Aims
A study examined the quality of the diet selected and the growth of young cattle grazing a buffel grass (Cenchrus ciliaris)–Centro (Centrosema brasilianum) pasture in a high-rainfall, seasonally dry, tropical environment in northern Australia to relate the diet selected to cattle growth.

Methods
During three annual cycles, young steers grazed a grass–Centro legume pasture at moderate stocking rate. LW was measured monthly, and diet attributes (legume content, DM digestibility (DMD) and crude protein concentration) were measured fortnightly by near-infrared reflectance spectroscopy analyses of faeces. Pasture available and species were measured twice annually.

Key results
The annual LW gain and diet attributes followed a consistent profile through the annual cycles. Following the seasonal break, the diet DMD and crude protein concentration increased abruptly to maxima (means 732 and 184 g/kg respectively), and then declined approximately linearly during the remainder of the WS and the wet–dry transition season (TS); DMD decreased by 0.49, 0.74 and 0.88 g/kg units per day. DMD and crude protein averaged 561 and 61 g/kg respectively during the DS. Centro comprised 86–291 g/kg of the pasture on offer, and averaged 283 and 205 g/kg of the diet during the TS and DS, respectively, but only 58 g/kg during the WS. Cattle selected for Centro during the TS and the DS, but not during the WS. Cattle LW gain reflected diet quality averaging 0.86, 0.59 and 0.12 kg/day during the WS, TS and DS respectively.

Conclusions
The Centro legume contributed substantially to the diet of growing cattle during the TS and DS, but not during the WS. The LW gains of cattle were moderate during the WS and TS, and low during the DS.

Implications
Centro in a buffel grass pasture contributed substantially to the diet, but nevertheless annual LW gain was only modest (mean 179, range 159–209 kg/annum).
Cloning, characterisation and expression profile of kisspeptin1 and the kisspeptin1 receptor in the hypothalamic–pituitary–ovarian axis of Chinese alligator Alligator sinensis during the reproductive cycle
Authors: Zhang Ruidong , Nie Haitao , Duan Shulong , Yan Peng , Izaz Ali , Wang Renping , Zhou Yongkang , Wu Xiaobing
Published: April 2020

Kisspeptin1 (Kiss1), a product of the Kiss1 gene, plays an important role in the regulation of reproduction in vertebrates by activating the Kiss1 receptor (Kiss1R) and its coexpression with gonadotrophin-releasing hormone (GnRH) in GnRH neurons. The purpose of this study was to clone the Kiss1 and Kiss1R genes found in the brain of Alligator sinensis and to explore their relationship with reproduction. The full-length cDNA of Kiss1 is 816bp, the open reading frame (ORF) is 417bp and the gene encodes a 138-amino acid precursor protein. The full-length cDNA of Kiss1R is 2348bp, the ORF is 1086bp and the gene encodes a 361-amino acid protein. Quantitative polymerase chain reaction showed that, except for Kiss1R expression in the hypothalamus, the expression of Kiss1 and Kiss1Rduring the reproductive period of A. sinensis was higher than that in the hypothalamus, pituitary gland and ovary during the hibernation period. The changes in GnRH2 mRNA in the hypothalamus were similar to those of GnRH1 and peaked during the reproductive period. This study confirms the existence of Kiss1 and Kiss1R in A. sinensis and the findings strongly suggest that Kiss1 and Kiss1R may participate in the regulation of GnRH secretion in the hypothalamus of alligators during the reproductive period. Furthermore, this is the first report of the full-length cDNA sequences of Kiss1 and Kiss1R in reptiles.
Importance of adding woodchips to local amendments for improving soil health and increasing yield in severely degraded soils of Northern China
Authors: Li Zhigang , Xie Yingzhong , Schneider Rebecca L. , Morreale Stephen J. , Bo Xiaoyan , Ni Xilu , Li Changxiao
Published: April 2020

Wood chips, together with crop straw and manure, were demonstrated as feasible amendments for improving overall soil health and enhancing plant growth in severely desertified areas in Northern China in our previous studies. However, the effects of their mixtures are unclear. In this study, we evaluated the effect of three different amendment materials, when used alone and in combination, on physical, chemical, and biological properties of desertified soil and on the associated growth of alfalfa in Ningxia, Northern China. Four replicate microcosms were set up containing sandy soil mixed with 3% (w/w) of each of the following treatments: cow manure (CM), corn straw (CS), and poplar branches (PB) and their mixtures CS-PB, CM-PB, CM-CS, and CM-CS-PB. Measurements were conducted 7 and 15 months after the start of the experiment. Results showed, as a whole, treatment CS-PB improved soil physical properties more than other amendments during the whole experimental period, compared with control. However, the best establishment of alfalfa in the first year and best growth in the second year occurred in the CM-CS-PB treatment. Moreover, available N and urease were the most important driving factors affecting alfalfa growth during the whole experimental period, as shown by redundancy analysis. However, interestingly, the CM-CS-PB also functioned better in maintaining N supply and accelerating microbial activity than the other amendments. Therefore, we concluded that wood chips have a unique advantage in improving overall soil health and alfalfa growth when combined with straw and manure as new amendments.
Feral cats are more abundant under severe disturbance regimes in an Australian tropical savanna
Authors: Davies Hugh F. , Maier Stefan W. , Murphy Brett P.
Published: April 2020

Abstract
ContextThere is an increasing awareness that feral cats play a key role in driving the ongoing decline of small mammals across northern Australia; yet, the factors that control the distribution, abundance and behaviour of feral cats are poorly understood. These key knowledge gaps make it near-impossible for managers to mitigate the impacts of cats on small mammals.
AimsWe investigated the environmental correlates of feral cat activity and abundance across the savanna woodlands of Melville Island, the larger of the two main Tiwi Islands, northern Australia.
MethodsWe conducted camera-trap surveys at 88 sites, and related cat activity and abundance to a range of biophysical variables, either measured in the field or derived from remotely sensed data.
Key resultsWe found that feral cat activity and abundance tended to be highest in areas characterised by severe disturbance regimes, namely high frequencies of severe fires and high feral herbivore activity.
ConclusionsOur results have contributed to the growing body of research demonstrating that in northern Australian savanna landscapes, disturbance regimes characterised by frequent high-severity fires and grazing by feral herbivores may benefit feral cats. This is most likely to be a result of high-severity fire and grazing removing understorey biomass, which increases the time that the habitat remains in an open state in which cats can hunt more efficiently. This is due to both the frequent and extensive removal, and longer-term thinning of ground layer vegetation by severe fires, as well as the suppressed post-fire recovery of ground layer vegetation due to grazing by feral herbivores.
ImplicationsManagement that reduces the frequency of severe fires and the density of feral herbivores could disadvantage feral cat populations on Melville Island. A firm understanding of how threatening processes interact, and how they vary across landscapes with different environmental conditions, is critical for ensuring management success.
Effects of solute content on microstructure of nano precipitate-fine grain synergistically reinforced copper alloys
Authors: Chen Kaixuan , Zhang Jiawei , Chen Xiaohua , Wang Zidong
Published: April 2020

Alloying of Fe, Co was reported to tailor microstructure of copper alloys into a nanoprecipitate-fine grain (NPFG) structure, i.e. nano-sized iron-rich precipitates dispersed inside refined grains. Here, we investigate the solute effect of Sn, Zn on NPFG structure in as-cast copper samples. Mechanisms are proposed to account for the solute effect on precipitate and grain features. Solutes restrict coarsening but facilitate undesirable morphology transition from spherical to angular of iron-rich precipitates. Meantime, solutes allow more precipitates to be active in the nucleation of copper and consequently induce finer grains. Minor Sn is added to optimise NPFG structure and leads to an excellent strength–ductility combination in Cu–1.5Fe–0.1Sn (wt-%) alloy. This work provides a solute-alloying strategy to achieve desired mechanical properties in metals.

GRAPHICAL ABSTRACT
Thermo-physical properties of Hastelloy X and Haynes 214 close to the melting range
Authors: Ulan kyzy Sonun , Völkl Rainer , Munz Oliver , Fischer Tim , Welzenbach Sarah , Glatzel Uwe
Published: April 2020

The nickel-based superalloys Hastelloy X and Haynes 214 are widely used for honeycomb liners; however, thermo-physical properties at temperatures close to the melting range are poorly described in the literature. Based on the thermo-physical properties, endothermic effects between 550°C and 650°C have been observed that develop due to the formation of the short-range order in both alloys and in Haynes 214, in addition to the short-range order, an increase in the specific heat capacity due to the γ′-precipitation up to 950° was detected. At low and intermediate temperatures, the Hastelloy X is significantly better suited than the Haynes 214. At high temperatures the Haynes 214 is superior to the Hastelloy X due to the dissolution of the γ′-phase.
MASTL promotes cell contractility and motility through kinase-independent signaling
Authors: Taskinen Maria Emilia , Närvä Elisa , Conway James R.W. , Hinojosa Laura Soto , Lilla Sergio , Mai Anja , De Franceschi Nicola , Elo Laura L. , Grosse Robert , Zanivan Sara , Norman Jim C. , Ivaska Johanna
Published: April 2020

Microtubule-associated serine/threonine-protein kinase-like (MASTL) is a mitosis-accelerating kinase with emerging roles in cancer progression. However, possible cell cycle–independent mechanisms behind its oncogenicity remain ambiguous. Here, we identify MASTL as an activator of cell contractility and MRTF-A/SRF (myocardin-related transcription factor A/serum response factor) signaling. Depletion of MASTL increased cell spreading while reducing contractile actin stress fibers in normal and breast cancer cells and strongly impairing breast cancer cell motility and invasion. Transcriptome and proteome profiling revealed MASTL-regulated genes implicated in cell movement and actomyosin contraction, including Rho guanine nucleotide exchange factor 2 (GEF-H1, ARHGEF2) and MRTF-A target genes tropomyosin 4.2 (TPM4), vinculin (VCL), and nonmuscle myosin IIB (NM-2B, MYH10). Mechanistically, MASTL associated with MRTF-A and increased its nuclear retention and transcriptional activity. Importantly, MASTL kinase activity was not required for regulation of cell spreading or MRTF-A/SRF transcriptional activity. Taken together, we present a previously unknown kinase-independent role for MASTL as a regulator of cell adhesion, contractility, and MRTF-A/SRF activity.
Bilateral comparison of 1 Ω and 10 kΩ standards (ongoing BIPM key comparisons BIPM.EM-K13.a and 13.b) between the NMC A*STAR (Singapore) and the BIPM
Authors: Rolland B , Stock M , Chua S W , Lim K H , Tan E
Published: April 2020

This report gives the result of a bilateral comparison of resistance between the NMC A*STAR (Singapore) and the BIPM carried out in 2018-2019. Two 1 Ω and two 10 kΩ travelling standards belonging to the BIPM were used. The comparison was carried out with an 'A-B-A' pattern of measurements; the standards were measured first at the BIPM for a period of about two months, then for a period of about one month at the NMC A*STAR, and finally again at the BIPM. The measurand was the 4 terminal dc resistance at low power. The BIPM was the pilot laboratory, and the comparison forms part of the ongoing BIPM key comparisons BIPM.EM-K13.a (for 1 Ω) and BIPM.EM-K13b (for 10 kΩ).

The results from the NMC A*STAR and the BIPM were found to be in good agreement, with a difference smaller than the relative expanded uncertainty (95% confidence, k = 2) of 0.064 × 10−6 for 1 Ω and 0.036 × 10−6 for 10 kΩ.

Main text

To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/.

The final report has been peer-reviewed and approved for publication by the CCEM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).