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51.
Shakir Ullah A. Qayyum 《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》2009,267(18):3059-3062
Here we describe a recently developed direct Monte Carlo program to study kinetic electron emission from SiO2 target. The program includes excitation of the target electrons (by projectile ions, recoiling target atoms and fast primary electrons), subsequent transport and escape of these electrons from the target surface. The program can be used to calculate the electron yields, distribution of electron excitation points in the target and other physical parameters of the emitted electrons. In order to demonstrate the capabilities of this program, we report a study on the kinetic electron emission from SiO2 induced by fast (1-10 keV) rare gas ions. The calculated kinetic electron yield for various ion energies and masses is in good agreement with the predictions of most frequently applied theoretical model. In addition, the effects of projectile energy, mass and impact angle on the depth distribution of electron excitation points and average escape depth of the outgoing electrons were investigated. It is important to mention that the existing experimental techniques are not capable to measure these parameters. 相似文献
52.
Wazir Muhammad Asad Ullah Gulzar Khan Tahir Zeb Khan Tauseef Jamaal Fawad Ullah Matiullah Khan Amjad Hussain 《核技术(英文版)》2018,(5)
For precise and accurate patient dose delivery,the dosimetry system must be calibrated properly according to the recommendations of standard dosimetry protocols such as TG-51 and TRS-398. However, the dosimetry protocol followed by a calibration laboratory is usually different from the protocols that are followed by different clinics, which may result in variations in the patient dose.Our prime objective in this study was to investigate the effect of the two protocols on dosimetry measurements.Dose measurements were performed for a Co-60 teletherapy unit and a high-energy Varian linear accelerator with 6 and 15 MV photon and 6, 9, 12, and 15 MeV electron beams, following the recommendations and procedures of the AAPM TG-51 and IAEA TRS-398 dosimetry protocols. The dosimetry systems used for this study were calibrated in a Co-60 radiation beam at the Secondary Standard Dosimetry Laboratory(SSDL) PINSTECH,Pakistan, following the IAEA TRS-398 protocol. The ratio of the measured absorbed doses to water in clinical setting,D_w(TG-51/TRS-398), was 0.999 and 0.997 for 6 and15 MV photon beams,whereas these ratios were 1.013,1.009, 1.003, and 1.000 for 6, 9, 12, and 15 MeV electron beams, respectively. This difference in the absorbed dosesto-water D_w ratio may be attributed mainly due to beam quality(K_Q) and ion recombination correction factor. 相似文献
53.
Sobia Noreen Sara Hasan Shazia Akram Ghumman Syed Nasir Abbas Bukhari Bushra Ijaz Huma Hameed Huma Iqbal Afeefa Aslam Mervat Abdelaziz Mohamed Elsherif Shazia Noureen Hasan Ejaz 《International journal of molecular sciences》2022,23(5)
The rapid progression in biomaterial nanotechnology apprehends the potential of non-toxic and potent polysaccharide delivery modules to overcome oral chemotherapeutic challenges. The present study is aimed to design, fabricate and characterize polysaccharide nanoparticles for methotrexate (MTX) delivery. The nanoparticles (NPs) were prepared by Abelmoschus esculentus mucilage (AEM) and chitosan (CS) by the modified coacervation method, followed by ultra-sonification. The NPs showed much better pharmaceutical properties with a spherical shape and smooth surface of 213.4–254.2 nm with PDI ranging between 0.279–0.485 size with entrapment efficiency varying from 42.08 ± 1.2 to 72.23 ± 2.0. The results revealed NPs to possess positive zeta potential and a low polydispersity index (PDI). The in-vitro drug release showed a sustained release of the drug up to 32 h with pH-dependence. Blank AEM -CS NPs showed no in-vivo toxicity for a time duration of 14 days, accompanied by high cytotoxic effects of optimized MTX loaded NPs against MCF-7 and MD-MBA231 cells by MTT assay. In conclusion, the findings advocated the therapeutic potential of AEM/CS NPs as an efficacious tool, offering a new perspective for pH-responsive routing of anticancer drugs with tumor cells as a target. 相似文献
54.
Priti Tagde Agnieszka Najda Kalpana Nagpal Giriraj T. Kulkarni Muddaser Shah Obaid Ullah Sebastian Balant Md. Habibur Rahman 《International journal of molecular sciences》2022,23(5)
Breast cancer is one of the most common types of cancer among women globally. It is caused by mutations in the estrogen/progesterone receptors and conventional treatment methods are commonly utilized. About 70–80 percent of individuals with the early-stage non-metastatic disease may be cured. Conventional treatment is far less than the optimal ratio, as demonstrated through the high mortality rate of women with this cancer. However, conventional treatment methods like surgery, radiotherapy, and chemotherapy are not as effective as expected and lead to concerns about low bioavailability, low cellular uptake, emerging resistance, and adverse toxicities. A nanomedicine-based approach is a promising alternative for breast cancer treatment. The present era is witnessing rapid advancements in nanomedicine as a platform for investigating novel therapeutic applications and modern intelligent healthcare management strategies. This paper focuses on nanomedicine-based therapeutic interventions that are becoming more widely accepted for improving treatment effectiveness and reducing undesired side effects in breast cancer patients. By evaluating the state-of-the-art tools and taking the challenges involved into consideration, various aspects of the proposed nano-enabled therapeutic approaches have been discussed in this review. 相似文献
55.
Out of the many promising applications of metal hydrides, refrigeration, heat pumping and heat transformation are important. In order to achieve improved performance, a novel three-alloy cycle is proposed in which, for heat input at an intermediate temperature, heat outputs at high temperature and also at warm temperature are obtained in addition to refrigeration. The performance of this cycle using the alloys LaNi4.6Sn0.4, LaNi4.7Al0.3 and MmNi4.5Al0.5 is studied based on thermodynamics and reaction kinetics. Coefficients of performance, half-cycle times and specific alloy outputs are evaluated. 相似文献
56.
Gold(Au)thin films were deposited on SiO2 substrate under argon(Ar)gas environment using RF(radio frequency)magnetron sputtering at room temperature for various... 相似文献
57.
Machine Learning - Covariance estimation for high-dimensional datasets is a fundamental problem in machine learning, and has numerous applications. In these high-dimensional settings the number of... 相似文献
58.
Maktabdar Oghaz Mahdi Maarof Mohd Aizaini Rohani Mohd Foad Zainal Anazida Shaid Syed Zainudeen Mohd 《Neural computing & applications》2019,31(6):1835-1853
Neural Computing and Applications - Texture analysis is devised to address the weakness of color-based image segmentation models by considering the statistical and spatial relations among the group... 相似文献
59.
Farid Ullah Khan 《国际能源研究杂志》2020,44(8):6894-6916
This work presents the fabrication and testing of a vibration-based single energy hybrid harvester (VSEHH). Electromagnetic and piezoelectric transduction mechanisms are utilized for energy extraction in the developed harvester. Electromagnetic portion of the device composed of a permanent magnet, planar coil and wound coil, however, for piezoelectric portion polyvinylidene difluoride (PVDF) membrane is used. In the harvester the PVDF membrane having the magnet is kept loose in order to exploit the spring softening nonlinearity. At lower base excitation levels (less than 0.5g) the response of the VSEHH is linear, however, from 0.5 to 2.5g the harvester exhibits spring softening nonlinearity and at acceleration levels greater than 2.5g, the spring hardening nonlinearity is invoked. Because of nonlinear behavior of the harvester, the shift of resonant frequency, the sudden jump-up and jump-down phenomena result in the enhancement of the harvester's frequency bandwidth. Under sinusoidal excitation and at 123 Hz frequency and 4g acceleration, the electromagnetic portion of the harvester produced 40.6 mV load voltage and 212.7 μW with planar coil and 73.5 mV load voltage and 319.1 μW power with wound coil. Moreover, under the same vibrations condition a load voltage of 2930 mV and power of 57.6 μW is generated by the piezoelectric portion of the harvester. Collectively, the harvester is capable of producing a power of 589.4 μW and a power density of 334.13 μW/cm3. Furthermore, when subjected to broadband random vibrations, two central frequency peaks are produced, one is due to spring softening and the other corresponds to the spring hardening of the membrane. 相似文献
60.
Adi Md Sikin Markus Walkling-Ribeiro Syed S. H. Rizvi 《Food and Bioprocess Technology》2017,10(12):2132-2145
Individual and combined effects of high pressure nitrous oxide (HPN2O), heat, and antimicrobials on the inactivation of Escherichia coli, Listeria innocua, and Bacillus atrophaeus endospores in milk were all evaluated after 20-min treatments. Stand-alone milk treatments with HPN2O (15.2 MPa), heat (45 and 65 °C), or nisin (50 and 150 IU mL?1) resulted in log10 reductions ranging only from 0.1 to 2.1 for E. coli and L. innocua. Combining HPN2O (15.2 MPa) with heat (65 °C) inactivated 6.0 and 5.1 log10 in the vegetative bacteria, respectively. Similarly, reductions of 5.9 and ≥ 6.0 log10 of respective E. coli and L. innocua cells in milk were achieved through a combination of HPN2O (15.2 MPa), heat (65 °C), and nisin (150 IU mL?1). A 2.5 log10 cycle inactivation of spores was obtained by HPN2O, nisin (at both 50 and 150 IU mL?1), and lysozyme (50 μg mL?1) at 85 °C. Combining these processing techniques resulted in significantly greater microbial inactivation (p < 0.05) than the sum of individual reductions from each treatment alone, indicating synergistic effects. HPN2O irrespective of processing temperatures did not cause any occurrence of sub-lethally injured cells or disruption in colloidal stability of milk at 65 and 85 °C (p ≥ 0.05). Color and pH changes in milk following the most demanding treatment conditions were minimal. 相似文献