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H. Abdel-Khalek,M.I. El-Samahi,Mohamed Abd- El Salam,Ahmed M. El-Mahalawy 한국물리학회 2018 Current Applied Physics Vol.18 No.12
Organic/inorganic ultraviolet photodetector was fabricated using thermal evaporation technique. Organic/inorganic heterojunction based on thermally evaporated copper (II) acetylacetonate thin film of thickness 200 nm deposited on an n-type silicon substrate is introduced. I–V characteristics of the fabricated heterojunction were investigated under UV illumination of intensity 65 mW/cm2. The diode parameters such as ideality factor, n, barrier height, ΦB, and reverse saturation current, Is, were determined using thermionic emission theory. The series resistance of the fabricated diode was determined using modified Nord's method. The estimated values of series resistance and barrier height of the diode were about 0.33 KΩ and 0.72 eV, respectively. The fabricated photodetector exhibited a responsivity and specific detectivity about 9 mA/W and 4.6×109 Jones, respectively. The response behavior of the fabricated photodetector was analyzed through ON-OFF switching behavior. The estimated values of rise and fall time of the present architecture under UV illumination were about 199 ms and 154 ms, respectively. Finally, enhancing the photoresponsivity of the fabricated photodetector, post-deposition plasma treatment process was employed. A remarkable modification of the device performance was noticed as a result of plasma treatment. These modifications are representative in a decrease of series resistance and an increase of photoresponsivity and specific detectivity. The process of plasma treatment achieved an increment of external quantum efficiency from 5.53% to 8.34% at −3.5 V under UV illumination.
H. Abdel-Khalek,Mohamed Abd- El Salam,Fatma M. Amin 한국물리학회 2019 Current Applied Physics Vol.19 No.4
In this work, the optoelectronic performance of organic/inorganic heterojunction photodiode based on alphasexithiophene (α-6T/n-Si) is introduced. A thin film of α-6T was deposited on the n-type silicon substrate by a thermal evaporation technique. The topographical properties of the α-6T thin film grown on the n-Si substrate were investigated using a field emission scanning electron microscope (FESEM) technique. A network of nanocrystalline needles over the film surface was observed which give rise to an improvement in the electric charge transport. The optical properties of the prepared thin film were investigated using a spectrophotometric technique. The high absorption of α-6T in UV and visible region suggested the ability of this architecture for UV and visible light detection. The I-V characteristics of the fabricated photodiode were investigated in dark and under different illumination intensities and different wavelengths. The present architecture showed a good response to halogen lamb light, where the estimated values of rising and falling time at 160 mW/cm2 were about 400 ms and 450 ms, respectively. The results show the possibility of using Au/α-6T/n-Si/Al structure as a photodetector for a wide range of the solar spectrum (UV–Visible).
Ahmed Abdel Khalek Abdel Razek,Nada Elsaid,Tamer Belal,Nihal Batouty,Ahmed Azab 대한초음파의학회 2022 ULTRASONOGRAPHY Vol.41 No.1
Purpose: This study assessed the combined accuracy of optic nerve sheath diameter (ONSD), strain ratio (SR), and shear wave elastography (SWE) of the optic nerve (ON) in patients with idiopathic intracranial hypertension (IIH). Methods: This prospective study was carried out on both ONs of 34 consecutive patients diagnosed with IIH and 16 age- and sex-matched healthy volunteers. All of the study participants were women. The ONSD, SR, and SWE of the ON were measured. The severity of papilledema of IIH patients was sub-classified into mild papilledema and moderate/severe papilledema. Results: The mean ONSD (5.6±1.1 mm), SR (0.7±0.1), and SWE (30.1±16.7 kPa) of the IIH patients were significantly different (P=0.001) from the ONSD (4.1±0.5 mm), SR (0.9±0.1), and SWE (8.2±3.4 kPa) of controls. The cutoff values of ONSD, SR, and SWE of the ON for differentiating IIH patients from controls were 5.45 mm, 0.8, and 10.3 kPa with areas under the curve (AUCs) of 0.91, 0.86, and 0.96 and accuracy values of 91%, 81%, and 93%, respectively. Combined SWE and ONSD and combined SWE, ONSD, and SR for differentiating IIH patients from controls revealed AUCs of 0.98 and 0.99 and accuracy values of 96% and 96%, respectively. ONSD, SR, and SWE showed significant differences between mild and moderate/ severe papilledema (P=0.001). Papilledema was correlated with SWE (r=0.8, P=0.001), ONSD (r=0.4, P=0.001), and SR (r=-0.4, P=0.001). Conclusion: The combination of ONSD, SR, and SWE may be helpful for diagnosing IIH, and a good indicator of the degree of papilledema. Purpose: This study assessed the combined accuracy of optic nerve sheath diameter (ONSD), strain ratio (SR), and shear wave elastography (SWE) of the optic nerve (ON) in patients with idiopathic intracranial hypertension (IIH).Methods: This prospective study was carried out on both ONs of 34 consecutive patients diagnosed with IIH and 16 age- and sex-matched healthy volunteers. All of the study participants were women. The ONSD, SR, and SWE of the ON were measured. The severity of papilledema of IIH patients was sub-classified into mild papilledema and moderate/severe papilledema.Results: The mean ONSD (5.6±1.1 mm), SR (0.7±0.1), and SWE (30.1±16.7 kPa) of the IIH patients were significantly different (P=0.001) from the ONSD (4.1±0.5 mm), SR (0.9±0.1), and SWE (8.2±3.4 kPa) of controls. The cutoff values of ONSD, SR, and SWE of the ON for differentiating IIH patients from controls were 5.45 mm, 0.8, and 10.3 kPa with areas under the curve (AUCs) of 0.91, 0.86, and 0.96 and accuracy values of 91%, 81%, and 93%, respectively. Combined SWE and ONSD and combined SWE, ONSD, and SR for differentiating IIH patients from controls revealed AUCs of 0.98 and 0.99 and accuracy values of 96% and 96%, respectively. ONSD, SR, and SWE showed significant differences between mild and moderate/severe papilledema (P=0.001). Papilledema was correlated with SWE (r=0.8, P=0.001), ONSD (r=0.4, P=0.001), and SR (r=-0.4, P=0.001).Conclusion: The combination of ONSD, SR, and SWE may be helpful for diagnosing IIH, and a good indicator of the degree of papilledema.
Abdel Razek Ahmed Abdel Khalek,Abdalla Ahmed,Elfar Reda,Ashmalla Germeen Albair,Ali Khadiga,Barakat Tarik 대한영상의학회 2020 Korean Journal of Radiology Vol.21 No.12
Objective: To assess diffusion tensor imaging (DTI) parameters of the hepatic parenchyma for the differentiation of biliary atresia (BA) from Alagille syndrome (ALGS). Materials and Methods: This study included 32 infants with BA and 12 infants with ALGS groups who had undergone DTI. Fractional anisotropy (FA) and mean diffusivity (MD) of the liver were calculated twice by two separate readers and hepatic tissue was biopsied. Statistical analyses were performed to determine the mean values of the two groups. The optimum cut-off values for DTI differentiation of BA and ALGS were calculated by receiver operating characteristic (ROC) analysis. Results: The mean hepatic MD of BA (1.56 ± 0.20 and 1.63 ± 0.2 x 10-3 mm2/s) was significantly lower than that of ALGS (1.84 ± 0.04 and 1.79 ± 0.03 x 10-3 mm2/s) for both readers (r = 0.8, p = 0.001). Hepatic MD values of 1.77 and 1.79 x 10-3 mm2/s as a threshold for differentiating BA from ALGS showed accuracies of 82 and 79% and area under the curves (AUCs) of 0.90 and 0.91 for both readers, respectively. The mean hepatic FA of BA (0.34 ± 0.04 and 0.36 ± 0.04) was significantly higher (p = 0.01, 0.02) than that of ALGS (0.30 ± 0.06 and 0.31 ± 0.05) for both readers (r = 0.80, p = 0.001). FA values of 0.30 and 0.28 as a threshold for differentiating BA from ALGS showed accuracies of 75% and 82% and AUCs of 0.69 and 0.68 for both readers, respectively. Conclusion: Hepatic DTI parameters are promising quantitative imaging parameters for the detection of hepatic parenchymal changes in BA and ALGS and may be an additional noninvasive imaging tool for the differentiation of BA from ALGS.
Aad, G.,Abbott, B.,Abdallah, J.,Abdel Khalek, S.,Abdinov, O.,Aben, R.,Abi, B.,Abolins, M.,AbouZeid, O. S.,Abramowicz, H.,Abreu, H.,Abreu, R.,Abulaiti, Y.,Acharya, B. S.,Adamczyk, L.,Adams, D. L.,Adelm Springer Berlin Heidelberg 2014 European Physical Journal C Vol.74 No.8
<P>The integrated elliptic flow of charged particles produced in Pb+Pb collisions at [FORMULA OMISSION] TeV has been measured with the ATLAS detector using data collected at the Large Hadron Collider. The anisotropy parameter, [FORMULA OMISSION], was measured in the pseudorapidity range [FORMULA OMISSION] with the event-plane method. In order to include tracks with very low transverse momentum [FORMULA OMISSION], thus reducing the uncertainty in [FORMULA OMISSION] integrated over [FORMULA OMISSION], a [FORMULA OMISSION] data sample recorded without a magnetic field in the tracking detectors is used. The centrality dependence of the integrated [FORMULA OMISSION] is compared to other measurements obtained with higher [FORMULA OMISSION] thresholds. The integrated elliptic flow is weakly decreasing with [FORMULA OMISSION]. The integrated [FORMULA OMISSION] transformed to the rest frame of one of the colliding nuclei is compared to the lower-energy RHIC data.</P>
Aad, G.,Abbott, B.,Abdallah, J.,Abdel Khalek, S.,Abdinov, O.,Aben, R.,Abi, B.,Abolins, M.,AbouZeid, O.S.,Abramowicz, H.,Abreu, H.,Abreu, R.,Abulaiti, Y.,Acharya, B.S.,Adamczyk, L.,Adams, D.L.,Adelman, North-Holland Pub. Co 2015 Physics letters. Section B Vol.740 No.-
<P><B>Abstract</B></P> <P>This Letter presents a search at the LHC for <I>s</I>-channel single top-quark production in proton–proton collisions at a centre-of-mass energy of 8 TeV. The analyzed data set was recorded by the ATLAS detector and corresponds to an integrated luminosity of 20.3 fb<SUP>−1</SUP>. Selected events contain one charged lepton, large missing transverse momentum and exactly two <I>b</I>-tagged jets. A multivariate event classifier based on boosted decision trees is developed to discriminate <I>s</I>-channel single top-quark events from the main background contributions. The signal extraction is based on a binned maximum-likelihood fit of the output classifier distribution. The analysis leads to an upper limit on the <I>s</I>-channel single top-quark production cross-section of 14.6 pb at the 95% confidence level. The fit gives a cross-section of <SUB> σ s </SUB> = 5.0 ± 4.3 pb , consistent with the Standard Model expectation.</P>
Aad, G.,Abbott, B.,Abdallah, J.,Abdel Khalek, S.,Abdinov, O.,Aben, R.,Abi, B.,Abolins, M.,AbouZeid, O. S.,Abramowicz, H.,Abreu, H.,Abreu, R.,Abulaiti, Y.,Acharya, B. S.,Adamczyk, L.,Adams, D. L.,Adelm Springer Berlin Heidelberg 2014 European Physical Journal C Vol.74 No.12
<P>The ratio of the production cross sections for [FORMULA OMISSION] and [FORMULA OMISSION] bosons in association with jets has been measured in proton–proton collisions at [FORMULA OMISSION] with the ATLAS experiment at the Large Hadron Collider. The measurement is based on the entire 2011 dataset, corresponding to an integrated luminosity of [FORMULA OMISSION]. Inclusive and differential cross-section ratios for massive vector bosons decaying to electrons and muons are measured in association with jets with transverse momentum [FORMULA OMISSION] and jet rapidity [FORMULA OMISSION]. The measurements are compared to next-to-leading-order perturbative QCD calculations and to predictions from different Monte Carlo generators implementing leading-order matrix elements supplemented by parton showers.</P>
Search for the lepton flavor violating decayZ→eμinppcollisions ats=8 TeVwith the ATLAS detector
Aad, G.,Abbott, B.,Abdallah, J.,Abdel Khalek, S.,Abdinov, O.,Aben, R.,Abi, B.,Abolins, M.,AbouZeid, O. S.,Abramowicz, H.,Abreu, H.,Abreu, R.,Abulaiti, Y.,Acharya, B. S.,Adamczyk, L.,Adams, D. L.,Adelm American Physical Society 2014 PHYSICAL REVIEW D - Vol.90 No.7
Aad, G.,Abbott, B.,Abdallah, J.,Khalek, S. Abdel,Abdinov, O.,Aben, R.,Abi, B.,Abolins, M.,AbouZeid, O. S.,Abramowicz, H.,Abreu, H.,Abreu, R.,Abulaiti, Y.,Acharya, B. S.,Adamczyk, L.,Adams, D. L.,Adelm Springer Berlin Heidelberg 2014 The European physical journal. C, Particles and fi Vol.74 No.6
<P>A search is presented for direct top squark pair production using events with at least two leptons including a same-flavour opposite-sign pair with invariant mass consistent with the [FORMULA OMISSION] boson mass, jets tagged as originating from [FORMULA OMISSION]-quarks and missing transverse momentum. The analysis is performed with proton–proton collision data at [FORMULA OMISSION] collected with the ATLAS detector at the LHC in 2012 corresponding to an integrated luminosity of 20.3 fb[FORMULA OMISSION]. No excess beyond the Standard Model expectation is observed. Interpretations of the results are provided in models based on the direct pair production of the heavier top squark state ([FORMULA OMISSION]) followed by the decay to the lighter top squark state ([FORMULA OMISSION]) via [FORMULA OMISSION], and for [FORMULA OMISSION] pair production in natural gauge-mediated supersymmetry breaking scenarios where the neutralino ([FORMULA OMISSION]) is the next-to-lightest supersymmetric particle and decays producing a [FORMULA OMISSION] boson and a gravitino ([FORMULA OMISSION]) via the [FORMULA OMISSION] process.</P>