Study of hydrodynamics and iodine removal by self-priming venturi scrubber

Ahad Jawaria,Rizwan Talha,Farooq Amjad,Waheed Khalid,Ahmad Masroor,Qureshi Kamran Rasheed,Siddique Waseem,Irfan Naseem 한국원자력학회 2023 Nuclear Engineering and Technology Vol.55 No.1

Filtered containment system is a passive safety system that controls the over-pressurization of containment in case of a design-based accidents by venting high pressure gaseous mixture, consisting of air, steam and radioactive particulate and gases like iodine, via a scrubbing system. An indigenous lab scale facility was developed for research on iodine removal by venturi scrubber by simulating the accidental scenario. A mixture of 0.2 % sodium thiosulphate and 0.5 % sodium hydroxide, was used in scrubbing column. A modified mathematical model was presented for iodine removal in venturi scrubber. Improvement in model was made by addition of important parameters like jet penetration length, bubble rise velocity and gas holdup which were not considered previously. Experiments were performed by varying hydrodynamic parameters like liquid level height and gas flow rates to see their effect on removal efficiency of iodine. Gas holdup was also measured for various liquid level heights and gas flowrates. Removal efficiency increased with increase in liquid level height and gas flowrate up to an optimum point beyond that efficiency was decreased. Experimental results of removal efficiency were compared with the predicted results, and they were found to be in good agreement. Maximum removal efficiency of 99.8% was obtained.

Current status of the anterior middle superior alveolar anesthetic injection for periodontal procedures in the maxilla

Ahad, Abdul,Haque, Ekramul,Tandon, Shruti The Korean Dental Society of Anesthsiology 2019 Journal of Dental Anesthesia and Pain Medicine Vol.19 No.1

Periodontal procedures require adequate anesthesia not only to ensure the patient's comfort but also to enhance the operator's performance and minimize chair time. In the maxilla, anesthesia is often achieved using highly traumatic nerve blocks, apart from multiple local infiltrations through the buccal vestibule. In recent years, anterior middle superior alveolar (AMSA) field block has been claimed to be a less traumatic alternative to several of these conventional injections, and it has many other advantages. This critical review of the existing literature aimed to discuss the rationale, mechanism, effectiveness, extent, and duration of AMSA injections for periodontal surgical and non-surgical procedures in the maxilla. It also focused on future prospects, particularly in relation to computer-controlled local anesthetic delivery systems, which aim to achieve the goal of pain-free anesthesia. A literature search of different databases was performed to retrieve relevant articles related to AMSA injections. After analyzing the existing data, it can be concluded that this anesthetic technique may be used as a predictable method of effective palatal anesthesia with adequate duration for different periodontal procedures. It has additional advantages of being less traumatic, requiring lesser amounts of local anesthetics and vasoconstrictors, as well as achieving good hemostasis. However, its effect on the buccal periodontium appears highly unpredictable.

Unveiling the synergistic effect of polysulfide additive and MnO2 hollow spheres in evolving a stable cyclic performance in Li-S batteries

Ahad, S.,Ragupathy, P.,Ryu, S.,Lee, H. W.,Kim, D. unknown 2017 Chemical Communications Vol. No.

<P>Herein, we demonstrate a synergistic approach involving polar-based oxide and polysulfide additives for effectively suppressing polysulfide dissolution during cycling. The MnO2 hollow spheres not only provide physical confinement for the polysulfide species but also enable strong chemical interactions between polysulfide species and oxides, while the added polysulfide furnishes a mass buffering effect and compensates for the capacity losses due to partial cathode dissolution during discharge. The capacity retentions of S/KB, S/KB/LiPS, S/KB/MnO2, and S/KB/MnO2/LiPS composite cathodes are 31%, 45%, 59%, and 91% respectively. The remarkable capacity retention of the S/KB/LiPS/MnO2 composite electrode is mainly attributed to the synergistic effect between MnO2 and polysulfide additives.</P>

Pattern of buccal and palatal bone density in the maxillary premolar region: an anatomical basis of anterior-middle superior alveolar (AMSA) anesthetic technique

Ahad, Abdul,Haque, Ekramul,Naaz, Sabiha,Bey, Afshan,Rahman, Sajjad Abdur The Korean Dental Society of Anesthsiology 2020 Journal of Dental Anesthesia and Pain Medicine Vol.20 No.6

Background: The anterior-middle superior alveolar (AMSA) anesthetic technique has been reported to be a less traumatic alternative to several conventional nerve blocks and local infiltration for anesthesia of the maxillary teeth, their periodontium, and the palate. However, its anatomic basis remains controversial. The present study aimed to determine if the pattern of cortical and cancellous bone density in the maxillary premolar region can provide a rationale for the success of the AMSA anesthetic technique. Method: Cone-beam computed tomography scans of 66 maxillary quadrants from 34 patients (16 men and 18 women) were evaluated using a volumetric imaging software for cortical and cancellous bone densities in three interdental regions between the canine and first molar. Bone density was measured in Hounsfield units (HU) separately for the buccal cortical, palatal cortical, buccal cancellous, and palatal cancellous bones. Mean HU values were compared using the Mann-Whitney U test and one-way ANOVA with post-hoc analysis. Results: Cancellous bone density was significantly lower (P ≤ 0.001) in the palatal half than in the buccal half across all three interdental regions. However, there was no significant difference (P = 0.106) between the buccal and palatal cortical bone densities at the site of AMSA injection. No significant difference was observed between the two genders for any of the evaluated parameters. Conclusions: The palatal half of the cancellous bone had a significantly lower density than the buccal half, which could be a reason for the effective diffusion of the anesthetic solution following a palatal injection during the AMSA anesthetic technique.

Development and Microstructural Characterization of a New Wrought High Entropy Superalloy

Ahad Shafiee,Mahmoud Nili‑Ahmadabadi,Hyoung Seop Kim,Mohammad Jahazi 대한금속·재료학회 2020 METALS AND MATERIALS International Vol.26 No.5

In this study, a newly developed γ′ precipitation hardened high entropy superalloy (designated as HES-A1 hereafter) wasproduced and its microstructural features were characterized. The new alloy composition is based on the major elementsof conventional IN718 alloy, however other elements were added or removed to minimize possible presence of δ (or γʺ)phase and increase the volume fraction of very fine γ′ precipitates instead. Broadening the hot working window, lowerdensity, and avoiding the use of expensive elements were other considerations taken into account in the design of the newalloy. CALPHAD (CALculation of PHAse Diagrams) and PhaComp methods were used for the prediction of phases andtheir evolutions. The microstructure of the HES-A1 alloy in as-cast, homogenized, hot rolled, annealed and aged conditionswere characterized using optical, scanning, and transmission electron microscopes as well as X-ray diffraction technique. The as-cast microstructure of HES-A1 contained 5.5% of Laves phase, which was reduced to less than 0.3% through thedevelopment of a homogenization treatment. Hot rolling with reductions up to 36% at 1015 °C did not produce any cracking,indicating a good forming potential for the new alloy. The application of double aging treatment, similar to the one forIN718 alloy, showed no presence of γʺ or formation of δ phase in the microstructure. HES-A1 has been designed with ahigher Al/(Ti + Nb) ratio and higher proportion of Al + Ti + Nb so that it could be mainly strengthened by γ′ precipitation. The average size of monomodal γ′ precipitates was smaller than that observed in conventional alloys after similar treatments.

Evaluation of phytochemical and antimicrobial properties of Commelina diffusa Burm. f.

Ahad Ali Khan,Torequl Islam,Samir Kumar Sadhu 경희대학교 융합한의과학연구소 2011 Oriental Pharmacy and Experimental Medicine Vol.11 No.4

The results revealed that different fractions of Commelina diffusa Burm. f. produced significant (p<0.001,p<0.01, p<0.05, p<0.02 and p<0.5) inhibitory activity against the test bacteria and fungi. Methanolic fraction produced the highest zone of inhibition against the test bacteria (11 to 19 mm) which was followed by diethyl etheric extract (3 to 9 mm) and petroleum etheric extract (1 to 2 mm). Again, the methanolic extract showed the highest activity (the lowest MICs; 15.62 to 62.5 μg/μl) against seven species among the 11. In case of diethyl etheric and petroleum etheric fractions MICs were found to be (15.62 to 125 μg/μl)and (31.25 to 500 μg/μl), respectively. The diethyl etheric fraction showed the highest zone of inhibition against the fungi (15 to 19 mm) which was followed by methanolic extract (12 to 19 mm) and petroleum etheric extract (1 to 9 mm). Against the fungi the diethyl etheric extract showed the highest activity (i.e. the lowest MICs; 15.62 to 31.25 μg/μl). In case of methanolic and petroleum etheric fractions minimum inhibitory concentrations were found to be (15.62 to 125 μg/μl)and (31.25 to 250 μg/μl), respectively.

Investigation of near dry EDM compared with wet and dry EDM processes

Ahad Gholipoor,Hamid Baseri,Mohammadreza Shabgard 대한기계학회 2015 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.29 No.5

Material removal rate (MRR), tool wear ratio (TWR) and surface roughness (SR) obtained by near-dry EDM process were comparedwith wet and dry EDM at three levels of discharge energy in drilling of SPK steel. Surface integrity machined by this process was studiedand compared with wet and dry EDM processes, by scanning electron microscopy (SEM). The results showed that at high level of dischargeenergy, wet EDM has the most MRR, TWR and SR, and dry EDM has the least MRR, TWR and SR, while at low dischargeenergy levels, near-dry EDM process has the most MRR and the least SR. SEM micrographs showed that the quality of surface obtainedby near-dry EDM process is better than others and the machined surfaces by near-dry EDM process have lower micro-cracks and craters,relatively.

STATIC ANALYSIS OF FUNCTIONALLY GRADED PIEZOELECTRIC BEAMS UNDER THERMAL LOADS BY THE HOMOTOPY PERTURBATION METHOD

Ahad Armin,Mostafa Abbasi,Iman Shafieenejad,Mohammad Reza Eslami 한국소음진동공학회 2008 한국소음진동공학회 국제학술대회논문집 Vol.2008 No.7

An investigation into the recovery of oxide copper from a complex copper ore using sulphidisation technique and hydroxamate and potassium amyl xanthate collectors

Ahad Zare,Asghar Azizi,Mohammad Karamoozian 한국자원공학회 2020 Geosystem engineering Vol.23 No.1

This study was aimed to increase the floatability of oxide copper from a complex copper sample. For this purpose, sulphidisation processes such as slug and controlled potential sulphidisation (CPS) and hydroxamate and potassium amyl xanthate (Z6) collectors were utilized and their results were compared with real conditions. The results indicated that about 9.46% of the recovery of oxide copper increased using 300g/t ammonium sulphide in the first step, and reached to 77.12%. Also, in this case, the recovery of sulphide copper was significantly improved. In addition, the findings demonstrated that applying 10 g/t of potassium octyl hydroxamate anionic collector, the recovery of oxide copper reached to 74.47% without any negative effect on the recovery of sulphide copper. Meanwhile, the simultaneous use of Z11 and Z6 as collector caused to increase about 3.63% of the recovery of oxide copper (71.29%). It was also found that the highest recovery of oxide copper could be obtained using CPS method and in this case, 10.34% of the oxide copper and 4.48% of the total copper improved and also the dosage of (NH4)2S decreased.

Experimental investigation of CO2 capture using sodium hydroxide particles in a fluidized bed

Ahad Ghaemi,Sareh Naeem,Shahrokh Shahhosseini 한국화학공학회 2016 Korean Journal of Chemical Engineering Vol.33 No.4

CO2 capture from air using sodium hydroxide solid sorbent in a laboratory scale fluidized bed reactor was investigated experimentally. The influence of three parameters of temperature, inlet CO2 volume percentage and inlet air flow rate on the CO2 removal rate was studied. Experimental results showed that the optimum rate was at 25 oC when the inlet CO2 volume percentage was 1%. The results also showed that the adsorption process was reactive, and the reaction mechanism depended on the reaction temperature. In addition, empirical observation revealed only one adsorption cycle happened at low temperatures (25-30 oC). As the temperature increased, the second adsorption cycle occurred and, finally, CO2 desorption cycle took place in the range of 90-115 oC.