All-optical Semiconductor Optical Amplifiers Using Quantum Dots (Optical Pumping)

In the first portion of this chapter, a short review on all-optical processing is presented. Following the ideas of all-optical processing, a basic unit cell is introduced for the realization of these systems. To this end, an all-optical semiconductor optical amplifier based on quantum dots (QD-SOA) is presented and used as the basic unit cell. Then, a novel scheme for a high-speed all-optical half-adder based on quantum dot semiconductor optical amplifiers has been theoretically and extensively analyzed. We accelerate the gain recovery process in QD-SOA with a control pulse (CP) using the cross-gain modulation (XGM) effect in QD-SOA (based on a novel work reported by Rostami et al published in IEEE J. Quantum Electron in 2010). In this proposed scheme, a pair of input data streams simultaneously drives the switch to produce sum and carry. The proposed scheme is driven by the pair of input data streasms for one switch between which the Boolean XOR function is to be executed to produce a sum-bit. Then, one of the input data is utilized to drive the second switch and another is used as input data for it to produce a carry-bit. In the proposed structure, we need to use an optical attenuator to reduce the power level of the optical signal. Thee, data pulse is at least an order of magnitude stronger than the incoming pulse; thereforehowever, only the input pulse can alter QD-SOA’s optical properties. Also, an all-optical cross-phase modulation (XPM) wavelength converter has been utilized to obtain an all-optical AND gate, which is logic CARRY. Logic SUM and CARRY are simultaneously realized in the proposed structure. The operation of the system is evaluated and demonstrated with a Tb/s bit rate. The proposed structure is mathematically modeled by writing rate equations and then is numerically simulated with success. High-speed operation capabilities of the proposed all-optical half-adder structure are evaluated by numerical simulation

Surface-Modified Graphene for Mid-Infrared Detection

In this chapter, morphology variation and electronic structure in a surface-modified graphene are demonstrated by both calculation and experimental results. The results indicate that the band structure and morphology of modified graphene sheets are altered because of changing in the type of hybridization of carbon atoms in the graphene sheet. Accordingly, the band gap of graphene can be tuned by surface modification using organic molecules. Then, modified graphene is used for fabrication of infrared detectors. The properties of unmodified graphene photodetectors were also measured so as to compare with modified graphene photodetectors. The results demonstrate that modification of graphene using organic ligands improved the detection parameters such as fast response time, electrical stability and low dark current. Moreover, the sensitivity of photodetectors based on modified graphene was significantly improved

Immiscible-Recycle Gas Injection to Enhance Recovery in an Iranian Naturally Fractured Reservoir: a Case Study with Emphasis on Uncertain Parameters

Utiskivanje recikliranog plina je proces iskorištavanja ležišta od kojeg se mnogo očekuje u proizvodnji nafte i plina. Metoda koristi kontinuirano utiskivanje rentabilnog obroka proizvedenog plina kako bi se održala energija ležišta i iskoristila viskozna sila kao pokretačka sila. Postoje brojne studije o utiskivanju recikliranog plina u konvencionalna ležišta, međutim postoje neki drugi čimbenici kao što su lokacija bušotina i vrsta završnog opremanja, obrok i tlak utiskivanja, koji jako djeluju na konačni rezultat ove metode, a većini njih nije uzimana u obzir. U ovoj studiji je proučen proces utiskivanja nemiscibilnog recikliranog plina u jedno od iranskih prirodno raspucanih karbonatnih ležišta na opsegu polja. Stvarni model heterogenosti je konstruiran i simuliran pomoću Eclipse-100 modula (softver za simulaciju ležišta). Ispitani su učinci radnih parametara, kao što su broj i lokacija injekcionih/proizvodnih bušotina, proizvodnih/injekcionih obroka, vrsta opremanja i perforirani produktivni interval a rezultat je uspoređen s metodom prirodnog iskorištavanja ležišta. Utvrđeno je da je, osjetljivost obzirom na broj bušotina, 1 injekcijska/2 proizvodne bušotine najučinkovitiji slučaj. Kapacitet proizvodnje od 500 m3/d (3 145 bbl/d) i tlak na dnu bušotine od 25 bara (362,6 psi), dali su veću proizvodnju nafte. Završno opremanje injekcionih bušotina u frakturi i proizvodnih bušotina u matriksu, ima bolju proizvodnost naftnog polja u odnosu na druge slučajeve. Štoviše, uočeno je da je najučinkovitija vrsta završnog opremanja injekcionih bušotina vertikalno, a za proizvodne bušotine horizontalno. Rezultati su pokazali da je moguće postići značajno sekundarno pridobivanje korištenjem optimalnih uvjeta za utiskivanje nemiscibilnog recikliranog plina u to ležište.Recycle-gas injection is a promising recovery process to produce oil and gas. The method uses continues injection of the produced gas at economical rates to keep the reservoirs energy up and using viscous force as the driving force. There are numerous studies done on recycle-gas injection in conventional reservoirs, however, there are some other factors such as location of wells and completion type, rate and pressure of injection which highly affect the final result of this method and failed to be considered in the majority of them. In this study, we investigate the immiscible recycle gas injection process in one of the Iranian carbonate naturally fractured reservoirs on a field scale. The real heterogeneous model was constructed and simulated by Eclipse-100 module. The effects of operational parameters, such as number and location of injection/production wells, production/injection rate, completion type and interval, on the immiscible gas injection performance were investigated and the result were compared with natural depletion method. It was found that, in sensitivity with number of the wells, 1 injection/2 production wells was the most efficient case. Also well oil production rate of 3 145 bbl/d (500 m3/d) and well bottom-hole pressure of 25 bar provided higher oil recovery. Completing of the injection wells in fracture and production wells in matrix has a better field oil efficiency in comparison to the other cases. Moreover, it was observed that the most efficient type of well completion for injection well is vertical and for production wells are horizontal. The results revealed that the substantial secondary oil recovery can be achieved using optimum conditions for immiscible recycle gas injection in this reservoir

Clinical Features and Risk Factors of Relapse and Mortality in Thrombotic Thrombocytopenic Purpura Patients: A Seven-Year Experience

Background: Thrombotic thrombocytopenic purpura (TTP) is associated with microangiopathic hemolytic anemia, thrombocytopenia, and microvascular thrombosis. No comprehensive report exists on clinical characteristics and risk factors of relapse and mortality in Iranian TTP patients. In this study, we aimed to report clinical features of Iranian TTP patients, to evaluate disease relapse and mortality rate and their associated risk factors. Materials and Methods: This study was a cohort study of patients diagnosed with microangiopathic hemolytic anemia admitted to the Shariati Hospital, Tehran, a referral center for TTP patients, from 2010 to 2017. Demographic, clinical, and laboratory data were recorded and patients were followed for 3 years regarding disease relapse and mortality. Results:  114 patients (80 female, 34 male) with a mean age of 39.3 ± 14.99 years were included.  Hematologic and neurologic symptoms were the most common manifestations. Abnormal laboratory findings at the presentation included thrombocytopenia, anemia, and elevated LDH. All patients were treated with plasma exchange, and 75.5% of them had a response to treatment, while the 3-year relapse and mortality rate was 23.6 and 26.3%.  Lower platelet count was a predictor of disease relapse. Age, hematological, or neurological initial presentation were associated with TTP mortality. Conclusion: Based on the largest study of TTP patients ever in Iran, the demographic and clinical characteristics of Iranian TTP patients are similar to other existing reports. Knowledge of the risk factors for TTP relapse and mortality could be useful to alert hematologists for prompt therapeutic actions when necessary

Mapping local patterns of childhood overweight and wasting in low- and middle-income countries between 2000 and 2017

A double burden of malnutrition occurs when individuals, household members or communities experience both undernutrition and overweight. Here, we show geospatial estimates of overweight and wasting prevalence among children under 5 years of age in 105 low- and middle-income countries (LMICs) from 2000 to 2017 and aggregate these to policy-relevant administrative units. Wasting decreased overall across LMICs between 2000 and 2017, from 8.4% (62.3 (55.1–70.8) million) to 6.4% (58.3 (47.6–70.7) million), but is predicted to remain above the World Health Organization’s Global Nutrition Target of <5% in over half of LMICs by 2025. Prevalence of overweight increased from 5.2% (30 (22.8–38.5) million) in 2000 to 6.0% (55.5 (44.8–67.9) million) children aged under 5 years in 2017. Areas most affected by double burden of malnutrition were located in Indonesia, Thailand, southeastern China, Botswana, Cameroon and central Nigeria. Our estimates provide a new perspective to researchers, policy makers and public health agencies in their efforts to address this global childhood syndemic

Frequency Modeling of Earthquake Occurrences by utilizing the Fourier Transform Method

Finding a suitable method for the accurate and reliable estimation of earthquake return periods is an important challenge for research in the field of earthquake engineering. Usually, the Gutenberg-Richter recurrence law is used to determine the average frequency of earthquakes with a magnitude greater than or equal to the specific value. The Gutenberg-Richter recurrence law can provide the value of the average return period, and cannot be used to determine the full details of return periods including the short, medium and long periods. Therefore, we considered the possibility of utilizing the discrete Fourier transform method to develop the frequency model for earthquake magnitudes. For this purpose, we used a series of sine functions with different values of amplitude, frequency, and phase as a prediction frequency model. To implement the proposed method, we used a catalog of earthquakes with magnitudes greater than 3.8 occurred within a radius of 50 kilometers around the Bojnord since 1990 to 2019. In addition to having the overall consistency with the frequencies of the Gothenburg-Richter recurrence law, the developed model provides more details of earthquake frequencies for different magnitudes. Additionally, there is a high correlation between the frequencies obtained by the frequency model and the tidal frequencies of the moon and sun. The correlation coefficient between the earthquake and tidal frequencies was obtained to be 93.7%. Considering the frequencies of the developed model reveals that the main return periods of the earthquakes in this region are 2, 6 and 10 months and 1 and 25 years

The Effectiveness of Physical Activity on Enhancing Generalized Anxiety Disorder: A Review Study

Background: The present article is a review with the aim of investigating the effects of exercise and physical activity on generalized anxiety disorder (GAD) in different populations. Methods: To collect information, articles were first searched using the keywords of “generalizes anxiety disorder”, “sport”, “acute exercise”, “aerobic training”, and “resistance training”. The research was conducted between 2015 and 2020, and the databases used included Google Scholar, PubMed, Science Direct, and Springer. Finally, 12 articles met the standard and set criteria and were selected. After selecting the articles, the information related to each extracted article was reviewed using a specific checklist and in summary form. Findings: The types of aerobic and strength training used to improve GAD in different people have had positive results (including improvement of sleep and personality and improvement of anxiety disorders). Research also shows that the mechanisms that cause exercise to have such effects are a combination of biological and psychological factors. Conclusion: Physical activity while reducing the symptoms and complications of mental illness can act as an effective treatment and even prevention for anxiety disorders such as GAD

High-Performance Solution Processed Inorganic Quantum-Dot LEDs

In this research paper, fabrication of novel CdSe\ZnS QD-LEDs with solution processing method is presented, and the impact of trap energy levels in the electron and hole transport levels on these QD-LEDs brightness is investigated. Two types of QD-LEDs are fabricated with ITO as the transparent anode electrode, NiO nanoparticles as the hole transport layer (HTL), CdSe\ZnS QDs as the luminescent layer, ZnO:Ga as the electron transport layer (ETL), and Al as the cathode electrode. The NiO nanoparticles are synthesized by the sol-gel or alternatively the electrochemical method. Formation of different trap levels is observed in the crystal structures of the NiO nanoparticles synthesized by each of these methods. Considering the electrochemically prepared NiO nanoparticles, it is found that the density of trap levels is higher in the crystal structure of the NiO nanoparticles synthesized by sol-gel method, and the device fabricated by the latter material shows higher performance. Calculation of the electronic structure of ZnO:Ga by DFT methods (GGA-PBE) indicates that doping of Ga in the structure of crystalline ZnO creates new energy levels in conduction band and intermediate bands at the bandgap of ZnO host. It facilitates electron injection from Al cathode to the ZnO:Ga ETL layer and from this layer to the QD-luminescent layer. The fabricated devices show turn-on lower voltages than 5 V in which a peak brightness of 500 and 340 cd.m(-2) is measured for the LEDs fabricated with sol-gel and electrochemically synthesized NiO nanoparticles, respectively