•A material law has been suggested that considers the influence of free water content by modifying a recently developed computational constitutive model for concrete.•The material law has been found ...to correlate well with available test data for concrete that contains different amount of free water.•A numerical study has been performed on the effect of free water content on concrete penetration.•The present model has been found to be in good agreement with the experimental observations for wet plain concrete targets struck transversely by an ogival-nosed projectile in terms of sizes of both impact and scabbing craters, time-histories of load, penetration and velocity.•It has been found that the impact resistance increases with increasing free water content which results in smaller penetration depth in wet concrete target than that in dry one in the case of penetration and smaller residual velocity for wet concrete slab than that for dry one in the case of perforation.
A numerical study is presented herein on the effect of free water content on the penetration of concrete targets subjected to projectile impact. The paper consists of two parts: the first part proposes a material law that considers the influence of free water content by modifying a recently developed computational constitutive model for concrete; the second part performs the numerical simulations of the penetration of plain concrete targets struck by an ogival-nosed projectile using the material law. The present material law takes into account pressure dependency, strain rate sensitivity, shear damage and tensile softening, loading path dependency (Lode angle) and free water content. Various equations are obtained and the values of relevant parameters are estimated. It is demonstrated that the modified constitutive model correlates well with available test data for concrete. It is also demonstrated that the present model predictions are in good agreement with the experimental observations for wet plain concrete targets struck transversely by an ogival-nosed projectile in terms of sizes of both impact and scabbing craters, time-histories of load, penetration and velocity and that the impact resistance increases with increasing free water content which results in smaller penetration depth in wet concrete target than that in dry one in the case of penetration and smaller residual velocity for wet concrete slab than that for dry one in the case of perforation.
A microwave-assisted extraction (MAE) and ultra high performance liquid chromatography coupled with diode array detection and time-of-flight mass spectrometry (UHPLC-DAD-TOF-MS) method was developed ...for simultaneous determination of 14 phenolic compounds in the root of
Pueraria lobata (Wild.) Ohwi and
Pueraria thomsonii Benth. Operational conditions of MAE were optimized by central composite design (CCD). The optimized result was 65% ethanol as extraction solvent, 17
mL of extraction volume, 100
°C of extraction temperature and 2
min of hold time. A Zorbax SB C
18 (50
mm
×
4.6
mm I.D., 1.8
μm) and gradient elution were used during the analysis. The chromatographic peaks of 14 investigated compounds in samples were successfully identified by comparing their retention time, UV spectra and TOF mass data with the reference substances. All calibration curves showed good linearity (
r
>
0.9997) within the test ranges. The intra-day and inter-day variations were less than 1.77% and 2.88%, respectively. The developed method was successfully applied to determine the investigated compounds in 10 samples of Radix Puerariae Lobatae and Radix Puerariae Thomsonii, respectively. The result indicated that MAE and UHPLC-DAD-TOF-MS system might provide a rapid method for the quality control of Radix Puerariae.
Multiterminal Inverse AC Josephson Effect Arnault, Ethan G; Larson, Trevyn F. Q; Seredinski, Andrew ...
Nano letters,
11/2021, Letnik:
21, Številka:
22
Journal Article
Recenzirano
Odprti dostop
When a Josephson junction is exposed to microwave radiation, it undergoes the inverse AC Josephson effectthe phase of the junction locks to the drive frequency. As a result, the I–V curves of the ...junction acquire “Shapiro steps” of quantized voltage. If the junction has three or more superconducting contacts, coupling between different pairs of terminals must be taken into account and the state of the junction evolves in a phase space of higher dimensionality. Here, we study the multiterminal inverse AC Josephson effect in a graphene sample with three superconducting terminals. We observe robust fractional Shapiro steps and correlated switching events, which can only be explained by considering the device as a completely connected Josephson network. We successfully simulate the observed behaviors using a modified two-dimensional RCSJ model. Our results suggest that multiterminal Josephson junctions are a playground to study highly connected nonlinear networks with novel topologies.
Summary
Background Staphylococcus aureus has a peculiar ability to colonize the skin of patients with eczema and atopic dermatitis (AD), and is consistently found in eczematous skin lesions in these ...patients. A correlation between the severity of the eczema and colonization with S. aureus has been demonstrated, and it has been determined that bacterial colonization is an important factor aggravating skin lesions. Patients colonized with S. aureus have been treated with antibiotics in several open and double‐blind placebo‐controlled studies, with conflicting results.
Objectives To investigate the colonizing features of S. aureus in the lesional and nonlesional skin of patients with eczema and AD in China and to compare the therapeutic effect of mupirocin plus hydrocortisone butyrate with vehicle ointment plus hydrocortisone butyrate.
Methods A multicentre, double‐blind randomized trial was conducted. Eczema Area and Severity Index (EASI) scores were evaluated before the start of the trial and on the 7th, 14th and 28th day of treatment. Swabs for bacterial isolation were taken from lesional skin before the start of the trial and on the 7th, 14th and 28th day of treatment, and from nonlesional skin only before the start of the trial. A combination topical therapy with mupirocin plus hydrocortisone butyrate ointment was used in the experimental group, with vehicle ointment plus hydrocortisone butyrate ointment as a control.
Results Of 327 patients enrolled in the study, 208 had eczema and 119 had AD. Bacteria were isolated from 70·2% of lesional and 32·7% of nonlesional skin samples from patients with eczema, of which S. aureus accounted for 47·3% and 27·9%, respectively. Bacteria were isolated from 74·8% of lesional and 34·5% of nonlesional skin samples from patients with AD, of which S. aureus accounted for 79·8% and 80·5%, respectively. The colonization density of S. aureus was markedly higher in lesional than in nonlesional skin, both in patients with eczema and with AD (P < 0·01, P < 0·05), and was positively correlated with lesion severity. Considering the EASI scores before and after treatment and the final effective rate, good therapeutic effects were obtained in both the combination experimental groups and the control groups (P < 0·01), and there were no differences in the global therapeutic effect between the two groups in patients with eczema and with AD (P > 0·05). However, in patients with eczema with a clinical score of > 8 or in patients with AD with a clinical score of > 7, the therapeutic effect in the experimental groups was superior to that in the control groups (P < 0·05) on the 7th day of treatment. There were no differences between the two groups on the 14th and 28th days of treatment (P > 0·05). Following the improvement of symptoms and signs of eczema and AD, the positive rates of bacteria and S. aureus were reduced on the 7th day of treatment.
Conclusions This study confirmed that lesional skin of patients with eczema and AD was more frequently colonized with S. aureus than was nonlesional skin. The more severe the eczema, the higher the colonization rate of S. aureus, and S. aureus was also more often present in lesional and nonlesional skin in patients with AD than in those with eczema. Staphylococcus aureus infection is related to the pathogenesis of eczema and AD. An antibiotic–corticosteroid combination and corticosteroid alone both gave good therapeutic effect in eczema and in AD, and both reduced colonization by S. aureus. Early combined topical therapy is beneficial to patients with moderate to severe eczema and AD, and it is unnecessary to use antibiotics at later stages of disease or in mild eczema or AD.
Aims
This study experimentally investigated the short-term (about 6 months) effects of roots of
Cynodon dactylon
on the gas permeability and gas diffusion coefficient of soils with different degrees ...of compaction.
Methods
Compacted soil planted with
Cynodon dactylon
were left outdoors for about 6 months for plant growth. The measurements of rooted and bare soils included gas permeability, gas diffusion coefficient, root characteristics and soil microstructure. The relative effects of different root characteristic parameters on gas permeability and gas diffusion coefficient were compared through grey relational analysis.
Results
The root volume ratio had a greater effect on gas permeability and gas diffusion coefficient, compared with root area index, root area ratio, root length density, and root biomass ratio. When the degree of compaction ≥ 85% (porosity ≤ 0.41, bulk density ≥ 1.56 g cm
−3
), the macro-pores at the root–soil interface increased gas permeability and gas diffusion coefficient, while negligible effects of roots on gas movement existed under degree of compaction of 80%. The increase in gas permeability by roots was more significant than that in gas diffusion coefficient. However, roots’ increase of gas movement generally decreased at higher root volume ratio due to roots-occupied soil pores. Finally, gas permeability and gas diffusion coefficient of rooted soil were well predicted by newly-developed empirical models considering the effect of root volume ratio.
Conclusions
Macro-pores at the root–soil interface tended to increase gas permeability and gas diffusion coefficient of soil with a degree of compaction ≥ 85%, while it is the opposite for root volume ratio.
Superconducting diodes are proposed nonreciprocal circuit elements that should exhibit nondissipative transport in one direction while being resistive in the opposite direction. Multiple examples of ...such devices have emerged in the past couple of years; however, their efficiency is typically limited, and most of them require a magnetic field to function. Here we present a device that achieves efficiencies approaching 100% while operating at zero field. Our samples consist of a network of three graphene Josephson junctions linked by a common superconducting island, to which we refer as a Josephson triode. The three-terminal nature of the device inherently breaks the inversion symmetry, and the control current applied to one of the contacts breaks the time-reversal symmetry. The triode’s utility is demonstrated by rectifying a small (nA scale amplitude) applied square wave. We speculate that devices of this type could be realistically employed in the modern quantum circuits.
The strengthening mechanism of the ultrafine-grained ferritic/martensitic steel (T91) prepared by equal-channel angular pressing (ECAP) is studied by microhardness measurement, transmission electron ...microscopy and internal friction. The results show that dislocation strengthening rather than grain boundary strengthening plays a dominant role in the increase in microhardness. Upon annealing at different temperatures, it is found that there is an evident decrease in microhardness between 650 and 700°C for the ECAPed specimens processed by 1 pass and 4 passes. An internal friction peak is also observed in the vicinity of 670°C for the ECAPed specimens during the first heating but disappears during the second heating. The TEM observations indicate that there is no evident change in the grain size for the ECAPed specimens before and after the annealing at 700°C for 1h. It is concluded that the softening around 670°C stems mainly from the dislocation annihilation.
Non-viral vesicle composing of low-molecular weight polyethylenimine-conjugated stearic acid-g-chitosan oligosaccharide (CSOSA-g-PEI) was synthesized for gene delivery and therapy. The synthesized ...CSOSA-g-PEI had good ion-buffer capabilities and DNA-binding capacity, which could form positively charged nano-sized particles (100-150 nm) with plasmid DNA; in vitro gene transfection tests demonstrated that CSOSA-g-PEI presented much lower cytotoxicity and corresponding transfection efficiency in comparison with Lipofectamine 2000 in both human cancer cells (Hela and MCF-7). The gene transfection of CSOSA-g-PEI/pDNA could be further enhanced in the presence of serum or by adding arginine during incubation of CSOSA-g-PEI micelles with plasmid DNA. The biodistribution experiments demonstrated CSOSA-g-PEI conjugate highly localized in the tumor tissue and indicated a persistently increased accumulation. In vivo antitumor activity results showed that CSOSA-g-PEI/plasmid pigment epithelium-derived factor formulation could effectively suppress the tumor growth (above 60% tumor inhibition) without systematic toxicity against animal body after intravenous injection.
Bulk Cu/Fe nanolamellar composites with different layer thickness were fabricated by cross accumulative roll bonding (CARB) technique. Here, annealing induced hardening and strengthening behaviors ...were observed in these composites as annealing temperature rises up to 400 °C. Especially, the increasing rate of strength and hardness are more remarkable in those with thinner layers. Then, mechanical properties gradually degrade after annealing at higher temperatures due to the destruction of layer structure. Detailed microstructural characterizations demonstrate that miraculous abnormal hardening of Cu/Fe nanolamellar composites induced by annealing is attributed not only to the density reduction of mobile dislocation inside heterogenic layers but also to the relaxation of non-equilibrium interphase boundaries. Furthermore, this phenomenon is closely correlated with the individual layer thickness, which is revealed by the diffusion effect of excess defects in the interfacial transition zones.
•The hardening and strengthening behavior induced by low-temperature annealing is observed in Cu/Fe nanolamellar composite.•Interfacial transition zones (ITZs) could modulate interior microstructure and dislocations density during annealing.•This hardening rate is closely correlated with layer thickness due to the diffusion effect of excess defects in the ITZs.
The AC Josephson effect manifests itself in the form of “Shapiro steps” of quantized voltage in Josephson junctions subject to radiofrequency (RF) radiation. This effect presents an early example of ...a driven–dissipative quantum phenomenon and is presently utilized in primary voltage standards. Shapiro steps have also become one of the standard tools to probe junctions made in a variety of novel materials. Here we study Shapiro steps in a widely tunable graphene-based Josephson junction in which the high-frequency dynamics is determined by the on-chip environment. We investigate the variety of patterns that can be obtained in this well-understood system depending on the carrier density, temperature, RF frequency, and magnetic field. Although the patterns of Shapiro steps can change drastically when just one parameter is varied, the overall trends can be understood and the behaviors straightforwardly simulated, showing some key differences from the conventional RCSJ model. The resulting understanding may help interpret similar measurements in more complex materials.
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