Technology and Integration Roadmap for Optoelectronic Memristor.

Optoelectronic memristors (OMs) have emerged as a promising optoelectronic Neuromorphic computing paradigm, opening up new opportunities for neurosynaptic devices and optoelectronic systems. These OMs possess a range of desirable features including minimal crosstalk, high bandwidth, low power consumption, zero latency, and the ability to replicate crucial neurological functions such as vision and optical memory. By incorporating large-scale parallel synaptic structures, OMs are anticipated to greatly enhance high-performance and low-power in-memory computing, effectively overcoming the limitations of the von Neumann bottleneck. However, progress in this field necessitates a comprehensive understanding of suitable structures and techniques for integrating low-dimensional materials into optoelectronic integrated circuit platforms. This review aims to offer a comprehensive overview of the fundamental performance, mechanisms, design of structures, applications, and integration roadmap of optoelectronic synaptic memristors. By establishing connections between materials, multilayer optoelectronic memristor units, and monolithic optoelectronic integrated circuits, this review seeks to provide insights into emerging technologies and future prospects that are expected to drive innovation and widespread adoption in the near future.

Organic and inorganic nanomaterials: fabrication, properties and applications.

Nanomaterials and nanoparticles are a burgeoning field of research and a rapidly expanding technology sector in a wide variety of application domains. Nanomaterials have made exponential progress due to their numerous uses in a variety of fields, particularly the advancement of engineering technology. Nanoparticles are divided into various groups based on the size, shape, and structural morphology of their bodies. The 21st century's defining feature of nanoparticles is their application in the design and production of semiconductor devices made of metals, metal oxides, carbon allotropes, and chalcogenides. For the researchers, these materials then opened a new door to a variety of applications, including energy storage, catalysis, and biosensors, as well as devices for conversion and medicinal uses. For chemical and thermal applications, ZnO is one of the most stable n-type semiconducting materials available. It is utilised in a wide range of products, from luminous materials to batteries, supercapacitors, solar cells to biomedical photocatalysis sensors, and it may be found in a number of forms, including pellets, nanoparticles, bulk crystals, and thin films. The distinctive physiochemical characteristics of semiconducting metal oxides are particularly responsible for this. ZnO nanostructures differ depending on the synthesis conditions, growth method, growth process, and substrate type. A number of distinct growth strategies for ZnO nanostructures, including chemical, physical, and biological methods, have been recorded. These nanostructures may be synthesized very simply at very low temperatures. This review focuses on and summarizes recent achievements in fabricating semiconductor devices based on nanostructured materials as 2D materials as well as rapidly developing hybrid structures. Apart from this, challenges and promising prospects in this research field are also discussed.

Threshold switching in nickel-doped zinc oxide based memristor for artificial sensory applications.

Electronic devices featuring biomimetic behaviour as electronic synapses and neurons have motivated the emergence of a new era in information and humanoid robotics technologies. In the human body, a nociceptor is a unique sensory neuron receptor that is capable of detecting harmful signals, leading to the central nervous system initiating a motor response. Herein, a nickel-doped zinc oxide (NZO)/Au based memristor is fabricated for the first time and characterized for artificial nociceptor application. For this, the introduction of a nickel-doped zinc oxide (NZO) layer between P++-Si and Au electrodes is used to eliminate the surface effects of the NZO layer, resulting in improved volatile threshold switching performance. Depending on the intensity, duration, and repetition rate of the external stimuli, this newly created memristor exhibits various critical nociceptive functions, including threshold, relaxation, allodynia, and hyperalgesia. The electron trapping/detrapping to/from the traps in the NZO layer is responsible for these nociceptive properties. This kind of NZO-based device produces a multifunctional nociceptor performance that is essential for applications in artificial intelligence systems, such as neural integrated devices with nanometer-sized features.

A survey on radiation protection awareness at various hospitals in Karachi, Pakistan.

Purpose: To assess the awareness level of radiation protection among the radiation workers (i.e. medical radiation technologists, medical physicists, and medical radiological professionals) at the selected radiology, nuclear medicine, and radiotherapy facilities in Karachi, Pakistan. Material and methods: This survey was carried out in Karachi which has the largest number of hospitals, including radiology, nuclear medicine, and radiotherapy facilities in all Pakistan. In this double-blind survey, a questionnaire was designed and distributed to one hundred and sixty five (165) medical radiation workers at their respective workplaces. These radiation workers included the medical radiation technologists, medical physicists, and medical radiological practitioners. These radiation workers had varying experiences, training records, education, and fields of specialization. Out of these total 165 respondents, 84 belonged to the radiology facilities, 20 to nuclear medicine facilities, and 61 to radiotherapy facilities. The educational level was classified as less than 16 years, and equal to or greater than 16 years. Similarly, the training was classified as "attended" or "never attended" and the experience as less than five years, between 5 and 10 years, and greater than ten years. The data was processed through SPSS (v.20) against a significance level (P ≤ 0.05). Results: The statistical analysis of the survey indicates that the radiation workers in radiology, nuclear medicine, and radiotherapy facilities in Karachi have limited awareness of radiation protection issues. The overall outcome of the survey also concluded that the awareness regarding radiation effects, radiation warning signs, and annual dose limit is optimum. However, the response to the questions related to patient protection remained unsatisfactory. Conclusion: This study showed that most of the radiation workers who participated in the survey lacked appropriate awareness of radiation protection measures. The radiation workers did show a better understanding of basic radiation protection parameters, such as the annual dose limit and radiation effects. However, the radiation workers needed an overall improvement in radiation protection awareness, particularly, related to patient protection. This awareness and knowledge should be improved through systematic and periodic trainings.

A Modified SiO2-Based Memristor with Reliable Switching and Multifunctional Synaptic Behaviors.

Dielectric SiO2 has possible uses as an active layer for emerging memory due to its high on/off ratio and low operation voltage. However, SiO2-based memory that relies on the conducting filament still has limited endurance and stability. Here, we have constructed a passivated layer of SiO2 using Ag-doped SrTiO3, which serves as a Ag ion reservoir for the control of filament formation. It is demonstrated that the modified memristor presents an excellent endurance switching and could stably be operated in an ambient environment for 20 days without visible degradation. Based on the reliable switching, the synaptic functions such as excitatory postsynaptic current, paired-pulse facilitation, transition from short-term memory to long-term memory, and potentiation/depression have also been implemented. Furthermore, a 7 × 7 pixel array made from memristors has successfully mimicked simple learning and forgetting behavior. The experimental results offer an alternative approach for SiO2-based memristors and a possibility to be applied in neuromorphic computing.

Analog Switching and Artificial Synaptic Behavior of Ag/SiOx:Ag/TiOx/p++-Si Memristor Device.

In this study, by inserting a buffer layer of TiOx between the SiOx:Ag layer and the bottom electrode, we have developed a memristor device with a simple structure of Ag/SiOx:Ag/TiOx/p++-Si by a physical vapor deposition process, in which the filament growth and rupture can be efficiently controlled during analog switching. The synaptic characteristics of the memristor device with a wide range of resistance change for weight modulation by implementing positive or negative pulse trains have been investigated extensively. Several learning and memory functions have been achieved simultaneously, including potentiation/depression, paired-pulse-facilitation (PPF), short-term plasticity (STP), and STP-to-LTP (long-term plasticity) transition controlled by repeating pulses more than a rehearsal operation, and spike-time-dependent-plasticity (STDP) as well. Based on the analysis of logarithmic I-V characteristics, it has been found that the controlled evolution/dissolution of conductive Ag-filaments across the dielectric layers can improve the performance of the testing memristor device.

Measurement of 6 MV small field beam profiles - comparison of micro ionization chamber and linear diode array with monte carlo code.

The objective of this study is to analyze small field photon beams acquired with commonly available detectors. Beam profiles of 6 MV photons from the Siemens Primus Linear Accelerator were measured with a micro ion chamber (IC CC01, IBA) and linear diode array (LDA-99SC, IBA). Data was acquired using a water phantom for small fields (0.5×0.5 cm2 to 4×4 cm2) at depth of maximum dose, 5 cm and 10 cm. Profiles were also generated with EGSnrc Monte Carlo code. Measured and simulated profiles were compared in terms of percentage difference of the area under the simulated and measured profiles (PD), ratio of the measured to simulated dose at the point of maximum deviation within the central region of profile (R), full width half maximum (FWHM) and penumbra. For field sizes ≥1×1 cm2, the maximum PD is 3.17 % and 2.87 % for IC and LDA respectively, whereas R is in the range of 0.95-1.05 for IC and 0.99-1.05 for LDA. LDA measured FWHM and penumbra are also in better agreement with the simulated results. This study demonstrated that LDA can be used for acquisition of beam profiles for field size as low as 1×1 cm2.

A review of international and developed practices of medical physics from a legislative and regulatory point of view and its applicability and comparison with Pakistan.

The importance of the medical physics profession and medical physicists is widely recognized by the international bodies like ILO, IAEA, EC, etc. The description of a medical physicist's qualification framework, their role and responsibilities have been addressed in the legislative and regulatory frameworks of developed countries like the USA (in 10CFR) and the EC (EC RP 174) and less comprehensively in developing counties like Pakistan. AFOMP has contributed positively in various regulatory and policy matters regarding the medical physics practices in Asian countries. Furthermore, the recommendations of IAEA's regional meeting on "Medical Physics in Europe-Current Status and Future Perspective" in Vienna, 2015, address the need and mechanism of a harmonized framework for medical physicists' qualifications. The lack of a comprehensive professional recognition framework becomes more challenging when we see that hi-tech diagnostic (e.g. PET CT) and therapeutic (e.g. cyberknife, VMAT, tomotherapy, etc.) modalities are now available in many parts of the world, including Pakistan which still have a basic level of medical physics qualification and practices. Therefore, international efforts like the above-mentioned IAEA-EC meeting in 2015; and by AFOMP activities related to training, qualification and recognition of medical physicists can provide a pathway to further improve medical physics practices in the developing world. The objective of this review is to (i) summarize the international practices for the legislation and regulation of medical physics, (ii) provide a brief overview of the medical physics practices in Pakistan and (iii) discuss the applicability of the IAEA-EC meeting's recommendations to the case of Pakistan. The review highlights the areas which are addressed in IAEA-EC meeting and could be beneficial to other nations as well, particularly, for low and middle income countries. The review also presents few suggestions how to progress with the medical physics profession in developing countries in general, and in Pakistan in particular. These suggestions also include further possible pathway the IAEA could consider, like IAEA project or meetings, to further strengthen the medical physics profession globally.

Low-Dimensional Materials and State-of-the-Art Architectures for Infrared Photodetection.

Infrared photodetectors are gaining remarkable interest due to their widespread civil and military applications. Low-dimensional materials such as quantum dots, nanowires, and two-dimensional nanolayers are extensively employed for detecting ultraviolet to infrared lights. Moreover, in conjunction with plasmonic nanostructures and plasmonic waveguides, they exhibit appealing performance for practical applications, including sub-wavelength photon confinement, high response time, and functionalities. In this review, we have discussed recent advances and challenges in the prospective infrared photodetectors fabricated by low-dimensional nanostructured materials. In general, this review systematically summarizes the state-of-the-art device architectures, major developments, and future trends in infrared photodetection.

Enhanced near-infrared absorber: two-step fabricated structured black silicon and its device application.

Silicon is widely used in semiconductor industry but has poor performance in near-infrared photoelectronic devices because of its high reflectance and band gap limit. In this study, two-step process, deep reactive ion etching (DRIE) method combined with plasma immersion ion implantation (PIII), are used to fabricate microstructured black silicon on the surface of C-Si. These improved surfaces doped with sulfur elements realize a narrower band gap and an enhancement of light absorptance, especially in the near-infrared range (800 to 2000 nm). Meanwhile, the maximum light absorptance increases significantly up to 83%. A Si-PIN photoelectronic detector with microstructured black silicon at the back surface exhibits remarkable device performance, leading to a responsivity of 0.53 A/W at 1060 nm. This novel microstructured black silicon, combining narrow band gap characteristic, could have a potential application in near-infrared photoelectronic detection.

Variations in the Dose Profiles of Physical and Virtual Wedge Filters of ONCOR Linear Accelerator.

PURPOSE: In this study, we measured the dose profiles of physical wedges (PWs) and virtual wedges (VW) for photon energies (6 MV and 15 MV), various field sizes (10 × 10, 15 × 15, and 20 × 20 cm2), depths (dmax, 10 cm, 20 cm), and wedge angles (15°, 30°, 45°, and 60°). This study was performed using a Siemens ONCOR IMRT Plus linear accelerator. The acquired dose profiles of PW and VW were compared and statistically analyzed. MATERIALS AND METHODS: The dose profiles were measured using IBA CC13 ion chamber in IBA Blue phantom (a three-dimensional water phantom). The source-to-surface distance was kept 100 cm and measurements were taken for 10 × 10, 15 × 15, and 20 × 20 cm2 field sizes and for 15°, 30°, 45°, and 60° PWs. These measurements were taken for both 6 MV and 15 MV photon energies. VW profiles were obtained using LDA-99 linear detector array (IBA, Germany). The percent off-axis dose difference between PW and VW profiles were calculated, analyzed, and plotted. Statistics on the measured data was applied using SPSS version 13. RESULTS AND CONCLUSION: The percent dose difference between PW and VW beam profiles were calculated at different off-axis positions. These dose variations increased in the wedge direction (toe region), but were negligible in the nonwedge direction. The results of one-way analysis of variance show that the dose variation between PW and VW are significant with off-axis positions, wedge angles, and depth, but are statistically nonsignificant with energy and field sizes. These variations could produce abnormal doses, especially in large field sizes and wedge angles in clinical applications, which could be avoided by understanding the behavior of wedge profiles and comparing the calculated (from treatment planning system) and measured (actual) doses.