Carbon nanomaterials (such as graphene, carbon nanotubes and nano-diamond) are widely used to synthesize metal matrix composites to strengthen metals such as Ti, Al and Cu. However, severe ...aggregation of these nano-scale reinforcements within the metal matrix has been a serious issue to achieve good performance metal matrix composites. In this study, we employed an in-situ co-precipitation method to decorate reduced graphene oxides with aluminium oxide nanoparticles (i.e. rGONs@Al2O3), which were then introduced into Ti-6Al-4 V matrix using the processes of ball milling and spark plasma sintering. Effects of co-precipitation temperature on the characteristics of rGONs/Al2O3 nanopowders, and their concentrations on microstructures and mechanical properties of the composites were systemically investigated. Characterization results revealed that γ-Al2O3 nanoparticles were uniformly wrapped with rGONs fakes, and numbers and sizes of Al2O3 nanoparticles were decreased with the increase of co-precipitation temperature. The rGONs@Al2O3 nanoparticles were uniformly coated onto the surfaces of the Ti-6Al-4 V powders, thus achieving a much finer grain size of matrix after the sintering process. As the content of rGONs@Al2O3 was increased, the strength of the composites was enhanced, whereas the elongation was slightly decreased. Due to effects of grain refinement and effective load transfer, the composite of 0.5 wt% rGONs@Al2O3 has achieved a high yield strength and an ultimate tensile strength of 950 MPa and 1022 MPa, which were ~120.4% and ~117.1% of the TC4 matrix, respectively. The fracture morphology was a mixture of cleavage fracture and ductile fracture.
•Introduced in-situ co-precipitation method to decorate rGO with Al2O3 into TC4 improve effectively the dispersion effect.•0.5 wt% rGO@Al2O3/TC4 composite achieved high YS and UTS of 950MPa and 1022MPa, ~120.4% and ~117.1% of the matrix.•Fracture morphology of composites was a mixture of cleavage fracture and ductile fracture.•Strengthening mechanism of the rGONs@Al2O3/TC4 composites are attributed to grain refinement and effectively load transfer.
Aim To prospectively evaluate the diagnostic accuracy of dual-source dual-energy computed tomography (DSDECT) for predicting the major component and determining the composition of urinary calculi in ...patients with urolithiasis, using postoperative in vitro Fourier transform infrared spectroscopy (FT-IR) analysis as the reference standard. Materials and methods Patients with known urolithiasis underwent preoperative DSDECT evaluation, and subsequently, underwent surgical removal of the stones. All patients were examined using the dual-energy renal stone protocol. Material-specific chromatic images were made using dedicated post-processing software. The final determination of stone composition was made using FT-IR postoperatively. Diagnostic parameters of DSDECT for predicting the major component and detecting the presence of four composition types were calculated. Results A total of 81 urinary calculi were included in this study. Forty-three were pure stones and 38 were mixed stones according to FT-IR. DSDECT correctly identified the major component of all pure stones and 36 mixed stones. The major component of two mixed stones with uric acid as the major component was falsely interpreted as calcium oxalate. The overall accuracy of DSDECT for predicting the major component of stones was 97.5% (79/81). The accuracy of DSDECT for detecting the presence of four types of composition, uric acid, cysteine, hydroxyapatite, and calcium oxalate, was 97.5% (79/81), 93.8% (76/81), 80.2% (65/81), and 93.8% (76/81), respectively. Conclusion DSDECT could accurately predict the major component of urinary calculi and detect uric acid, cysteine, and calcium oxalate with a satisfactory accuracy.
Infection prevention and public health are a vital concern worldwide, especially during pandemics such as COVID-19 and seasonal influenza. Frequent manual disinfection and use of chemical spray ...coatings at public facilities are the typical measures taken to protect people from coronaviruses and other pathogens. However, limitations of human resources and coating durability, as well as the safety of disinfectants used are the major concerns in society during a pandemic. Non-leachable antimicrobial agent poly(hexamethylene biguanide) (PHMB) was mixed into photocurable liquid resins to produce novel and tailor-made covers for public facilities via digital light processing, which is a popular 3D printing technique for satisfactory printing resolution. Potent efficacies of the 3D-printed plastics were achieved in standard antibacterial assessments against
,
and
. A total of 99.9% of Human coronavirus 229E was killed after being in contact with the 3D-printed samples (containing the promising PHMB formulation) for two hours. In an eight-week field test in Hong Kong Wetland Park, antibacterial performances of the specially designed 3D-printed covers analysed by environmental swabbing were also found to be satisfactory. With these remarkable outcomes, antimicrobial products prepared by digital light processing 3D printing can be regarded as a reliable solution to long-term infection prevention and control.
Background. Oseltamivir resistance in A(H1N1)pdm09 influenza is rare, particularly in untreated community cases. Sustained community transmission has not previously been reported. Methods. Influenza ...specimens from the Asia—Pacific region were collected through sentinel surveillance, hospital, and general practitioner networks. Clinical and epidemiological information was collected on patients infected with oseltamivir-resistant viruses. Results. Twenty-nine (15%) of 191 A(H1N1)pdm09 viruses collected between May and September 2011 from Hunter New England (HNE), Australia, contained the H275Y neuraminidase substitution responsible for oseltamivir resistance. Only 1 patient had received oseltamivir before specimen collection. The resistant strains were genetically very closely related, suggesting the spread of a single variant. Ninety percent of cases lived within 50 kilometers. Three genetically similar oseltamivir-resistant variants were detected outside of HNE, including 1 strain from Perth, approximately 4000 kilometers away. Computational analysis predicted that neuraminidase substitutions V241I, N369K, and N386S in these viruses may offset the destabilizing effect of the H275Y substitution. Conclusions. This cluster represents the first widespread community transmission of H275Y oseltamivir-resistant A(H1N1)pdm09 influenza. These cases and data on potential permissive mutations suggest that currently circulating A(H1N1)pdm09 viruses retain viral fitness in the presence of the H275Y mutation and that widespread emergence of oseltamivir-resistant strains may now be more likely.
Abstract
A sub-array of the Large High Altitude Air Shower Observatory (LHAASO), KM2A is mainly designed to observe a large fraction of the northern sky to hunt for γ-ray sources at energies above 10 ...TeV. Even though the detector construction is still underway, half of the KM2A array has been operating stably since the end of 2019. In this paper, we present the KM2A data analysis pipeline and the first observation of the Crab Nebula, a standard candle in very high energy γ-ray astronomy. We detect γ-ray signals from the Crab Nebula in both energy ranges of 10
100 TeV and
100 TeV with high significance, by analyzing the KM2A data of 136 live days between December 2019 and May 2020. With the observations, we test the detector performance, including angular resolution, pointing accuracy and cosmic-ray background rejection power. The energy spectrum of the Crab Nebula in the energy range 10-250 TeV fits well with a single power-law function d
N
/d
E
= (1.13
0.05
0.08
)
10
(
E
/20 TeV)
cm
s
TeV
. It is consistent with previous measurements by other experiments. This opens a new window of γ-ray astronomy above 0.1 PeV through which new ultrahigh-energy γ-ray phenomena, such as cosmic PeVatrons, might be discovered.
Abstract We report the timing analysis of PSR J1846−0513, a pulsar discovered by the Five-hundred-meter Aperture Spherical radio Telescope (FAST) in Commensal Radio Astronomy FAST Survey. The pulsar ...possesses a spin period of 23.36 ms and a spin-down rate ( P ̇ ) of 1.0106(3) × 10 −18 s s −1 , and it is located in an eccentric orbit ( e ∼0.208) with an orbital period of 0.61 days. The characteristic age and surface magnetic field of the pulsar are found to be 366.62 Myr and 4.9178 × 10 9 G, respectively, indicating that it is a recycled pulsar. Using over two years of timing data, we measure the periastron advance ω ̇ = 0.8956(8) deg yr −1 . By assuming that this effect is purely relativistic, we have estimated the total mass M = 2.6287(35) M ⊙ and obtained an upper limit for the pulsar mass and a lower limit for the companion’s mass. Our results indicate that this is a double neutron star system.
To investigate whether computed tomography (CT) texture analysis (TA) can be used to differentiate non-clear-cell renal cell carcinoma (non-ccRCC) from clear-cell RCC (ccRCC) and classify non-ccRCC ...subtypes.
One hundred ccRCC and 27 non-ccRCC (12 papillary and 15 chromophobe) were analysed. Texture parameters quantified from multiphasic CT images were compared for the objectives. Receiver operating characteristic (ROC) analysis was performed and the area under the ROC curve (AUC) was calculated. The optimal discriminative texture parameters were used to produce support vector machine (SVM) classifiers. Diagnostic accuracy and 10-fold cross-validation was performed.
Compared to ccRCC, non-ccRCC had significantly lower mean grey-level intensity (mean), standard deviation (SD), entropy, mean of positive pixels (MPP), and higher kurtosis (p<0.001). A model incorporating SD, entropy, MPP, and kurtosis produced an AUC of 0.94±0.03 with an accuracy of 87% (sensitivity=89%, specificity=92%) to identify non-ccRCC from ccRCC. Compared to chromophobe RCC, papillary RCC had significantly lower mean and MPP (p=0.002). A model incorporating SD, MPP, and skewness resulted in an AUC of 0.96±0.04 with an accuracy of 78% (sensitivity=87%, specificity=92%) to differentiate between papillary and chromophobe RCC.
CT TA could potentially be used as a less invasive tool to classify histological subtypes of RCC.
•CT texture analysis assists histological classification of renal cell carcinoma (RCC).•Non-clear cell RCC demonstrates lower Mean, SD, entropy, MPP and higher kurtosis.•Combining SD, entropy, MPP and kurtosis could accurately identify non-clear cell RCC.•Papillary RCC shows significantly lower Mean and MPP compared to chromophobe RCC.•SD, MPP and skewness combined could differentiate papillary from chromophobe RCC.
ABSTRACT
We report the follow-up of 10 pulsars discovered by the Five-hundred-metre Aperture Spherical radio-Telescope (FAST) during its commissioning. The pulsars were discovered at a frequency of ...500-MHz using the ultrawide-band (UWB) receiver in drift-scan mode, as part of the Commensal Radio Astronomy FAST Survey (CRAFTS). We carried out the timing campaign with the 100-m Effelsberg radio-telescope at L-band around 1.36 GHz. Along with 11 FAST pulsars previously reported, FAST seems to be uncovering a population of older pulsars, bordering and/or even across the pulsar death-lines. We report here two sources with notable characteristics. PSR J1951+4724 is a young and energetic pulsar with nearly 100 per cent of linearly polarized flux density and visible up to an observing frequency of 8 GHz. PSR J2338+4818, a mildly recycled pulsar in a 95.2-d orbit with a Carbon–Oxygen white dwarf (WD) companion of $\gtrsim 1\, \rm {M}_{\odot }$, based on estimates from the mass function. This system is the widest WD binary with the most massive companion known to-date. Conspicuous discrepancy was found between estimations based on NE2001 and YMW16 electron density models, which can be attributed to underrepresentation of pulsars in the sky region between Galactic longitudes 70° < l < 100°. This work represents one of the early CRAFTS results, which start to show potential to substantially enrich the pulsar sample and refine the Galactic electron density model.
Accurate prediction of aerobic capacity is necessary to guide appropriate exercise prescription. It is common to use 6-minute walk distance (6MWD) to predict peak oxygen uptake (VO.sub.2peak) in the ...clinical environment. The aim of this study was to determine whether prediction of VO.sub.2peak can be improved by the inclusion of cardiovascular indices derived by impedance cardiography (ICG) during the 6MWT. A total of 62 healthy university students aged 21±1 years completed in separate days, a cardiopulmonary exercise test (CPET) and two 6MWTs (30 min apart), during which heart rate (HR), stroke volume (SV) and cardiac output (CO) were measured by ICG (PhysioFlow.sup.® PF07 Enduro.sup.TM). The CPET was conducted with the Ergoselect 200 Ergoline and oxygen consumption measured by a MasterScreen.sup.TM CPX breath-by-breath metabolic cart. Multiple regression analyses were conducted to generate VO.sub.2peak prediction equations using 6MWD with, or without the cardiovascular indices recorded at the end of the best performed 6MWT as predictor variables. The mean peak HR (bpm), SV (ml) and CO (L/min) recorded during 6MWT were 156±18, 95.6±9, 15±2.8 and during CPET were 176±16, 91.3±8, 16.2±2.7, respectively. Analyses revealed the following VO.sub.2peak prediction equation: VO.sub.2peak = 100.297+(0.019x6MWD)+(-0.598xHR.sub.6MWT )+(-1.236xSV.sub.6MWT) + (8.671 x CO.sub.6MWT). This equation has a squared multiple correlation (R.sup.2) of 0.866, standard error of the estimate (SEE) of 2.28 mL/kg/min and SEE:VO.sub.2peak (SEE%) of 7.2%. Cross-validation of equation stability using predicted residual sum of squares (PRESS) statistics showed a R.sup.2 (R.sub.p .sup.2 ), SEE (SEE.sub.p) and SEE.sub.p % of 0.842, 2.38 mL/kg/min and 7.6% respectively. The minimal shrinkage of R.sup.2 implied regression model stability. Correlation between measured and predicted VO.sub.2peak using this equation was strong (r = 0.931, p<0.001). When 6MWD alone was used as the predictor for VO.sub.2peak, the generated equation had a lower R.sup.2 (0.549), and a higher SEE (4.08 mL/kg/min) and SEE% (12.9%). This is the first study which included cardiac indices during a 6MWT as variables for VO.sub.2peak prediction. Our results suggest that inclusion of cardiac indices measured during the 6MWT more accurately predicts VO.sub.2peak than using 6MWD data alone.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
ABSTRACT
The follow-up timing observations were carried out for 24 pulsars discovered with the Five-hundred-meter Aperture Spherical radio Telescope (FAST) in Commensal Radio Astronomy FAST Survey. ...We report their phase-connected timing ephemeris, polarization pulse profiles, and Faraday rotation measurements. With their spin periods spanning from 2.995 ms to 4.34 s, their period derivatives were determined to spread between 7.996(8) × 10−21 and 9.83(3) × 10−15 s s−1, which imply that they have characteristic ages from 1.97 × 106 to 5.93 × 109 yr. It is inferred that PSRs J0211+4235 and J0518+2431 are beyond the ‘traditional death line’. PSR J0211+4235 is beyond the ‘death valley’. The death line model of Zhang et al. also cannot explain the radio presence of PSR J0211+4235. This suggests that radiation theory needs to be improved. Besides, ten of the 22 canonical pulsars show nulling phenomena. Moreover, PSR J1617+1123 exhibits variation of emission and J0540+4542 shows subpulse drifting. The DM of five pulsars is larger than the estimated by the YMW16 electron density model, which could suggest that electron density models need updates for higher Galactic latitude regions. PSRs J0447+2447 and J1928−0548 are isolated millisecond pulsars. With their flux densities spanning from 5(1)–553(106) μJy, some of these new pulsars found by FAST are distant, dim, and low-$\dot{E}$ ones and are suitable for testing pulsar emission theories.
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