Spin glass behavior and critical analysis across the magnetic phase transition in Gd2CoMnO6: dc magnetization and ac susceptibility study

Bhatti Ilyas Noor,Bhatti Imtiaz Noor 한국물리학회 2022 Current Applied Physics Vol.39 No.-

We report here on critical analysis across magnetic phase transition and spin dynamics in Gd2CoMnO6. We found that this material behaves differently below and above the applied magnetic field of 20 kOe. The magnetic phase transition switches from nearly mean-field type to unusual class and Tc shifts towards the high temperature above 20 kOe field. The nature of the magnetic phase transition is explored by carrying out critical analysis at low as well as at high magnetic field. The critical exponents obtained at low field using Kouvel-Fisher method are β = 0.65 (2) γ = 0.90 (2), δ = 2.43 and Tc = 120 K. Apparently, these values of critical exponents appear close to mean-field model. For high field the critical exponents are β = 1.24 (2) γ = 0.64 (5), δ = 1.51 (3) and Tc = 128 K. The critical exponents show significant deviation from any universal class. This switchover in the nature of the magnetic phase transition is unique and not seen in many compounds. The formation of non-Griffiths-like clusters in this compound can be a reason for such unique behavior. Further, ac susceptibility has been measured to understand the spin dynamics in detail. The dispersion of frequency-dependent χac below Tc confirms a spin glass state in this material. The observed value of τo and To indicate the slow dynamic spin which is caused by co-existence of Co/Mn spin magnetic moments. The magneto-caloric effect is also presented for Gd2CoMnO6 in this study. The magnetic study and critical analysis across the phase transition reveal a switchover in the nature of phase transition in this material. A non-Griffiths like cluster formation above Tc is found and dynamic susceptibility study reveals a spin glass state below Tc in Gd2CoMnO6.

Compact PIFA for Mobile Terminals Supporting Multiple Cellular and Non-Cellular Standards

Bhatti, R.A.,Yun-Taek Im,Seong-Ook Park IEEE 2009 IEEE transactions on antennas and propagation Vol.57 No.9

<P>A novel multiband planar inverted-F antenna (PIFA) covering ten frequency bands has been proposed for personal wireless communications terminals. The design is based on the combination of various techniques that are used for designing multiband/broadband antennas. We used a shorted parasitic patch efficiently coupled to the driven patch, a quarter-wave resonator connected to the feed strip in parallel with the main patch, and four slits in the main radiator to excite various current modes in the antenna structure. The antenna is designed within a volume of 4.0 times 2.0 times 0.8 cm<SUP>3</SUP> and it can be used to serve the following wireless communication systems: Global System for Mobile Communications (GSM-900), Digital Communications System (DCS), Personal Communication Service (PCS), Universal Mobile Telecommunications System (UMTS), WiBro at 2.35 GHz, Bluetooth, Satellite-Digital Multimedia Broadcasting (SDM-B) at 2.65 GHz, WiMAX at 3.5 GHz, and the two bands (5.15-5.35 GHz and 5.725-5.875 GHz) for the wireless Local Area Network (WLAN) standards. A prototype antenna was fabricated and tested for input reflection coefficient and radiation performances. The measured and simulated results have been presented and discussed. Important geometrical parameters determining the multiband performances of the antenna have been explained in the paper.</P>

Catalyst-aided Regeneration of Amine Solvents for Efficient CO₂ Capture Process

Bhatti, Umair H.,Sultan, Haider,Cho, Jin Soo,Nam, Sungchan,Park, Sung Youl,Baek, Il Hyun The Korean Society for Energy 2019 에너지공학 Vol.28 No.4

Thermal amine scrubbing is the most advanced CO₂ capture technique but its largescale application is hindered due to the large heat requirement during solvent regeneration step. The addition of a solid metal oxide catalysts can optimize the CO₂ desorption rate and thus minimize the energy consumption. Herein, we evaluate the solvent regeneration performance of Monoethanolamine (MEA) and Diethanolamine (DEA) solvents without and with two metal oxide catalysts (TiO₂ and V₂O₅) within a temperature range of 40-86℃. The solvent regeneration performance was evaluated in terms of CO₂ desorption rate and overall amount of CO₂ desorbed during the experiments. Both catalysts improved the solvent regeneration performance by desorbing greater amounts of CO₂ with higher CO₂ desorption rates at low temperature. Improvements of 86% and 50% in the CO₂ desorption rate were made by the catalysts for MEA and DEA solvents, respectively. The total amount of the desorbed CO₂ also improved by 17% and 13% from MEA and DEA solvents, respectively. The metal oxide catalyst-aided regeneration of amine solutions can be a new approach to minimize the heat requirement during solvent regeneration and thus can remove a primary shortfall of this technology.

Outcomes of Triple-Negative Versus Non-Triple-Negative Breast Cancers Managed with Breast-Conserving Therapy

Bhatti, Abu Bakar Hafeez,Khan, Amina Iqbal,Siddiqui, Neelam,Muzaffar, Nargis,Syed, Aamir Ali,Shah, Mazhar Ali,Jamshed, Arif Asian Pacific Journal of Cancer Prevention 2014 Asian Pacific journal of cancer prevention Vol.15 No.6

Background: Triple negative breast cancer is associated with aggressive behavior and high risk of local and regional failure. Aggressive surgical intervention is considered suitable. This makes role of breast conserving therapy (BCT) debatable in these patients. The objective of this study was to compare outcome of BCT for triple negative versus non-triple negative breast cancer. Materials and Methods: Medical records of patients who underwent breast conserving therapy from 1999 to 2009 at Shaukat Khanum Cancer Hospital and had complete receptor status information were extracted. Patients were divided into triple negative breast cancer (TNBC) and non-TNBC. Patient characteristics, medical treatment modalities and adverse events were compared. Expected five year locoregional recurrence free, disease free and overall survival was calculated. The Cox proportional hazard model was used to identify independent predictors of outcome. Results: A total of 194 patients with TNBC and 443 with non-TNBC were compared. Significant difference was present for age at presentation (p<0.0001), family history (p=0.005), grade (p<0.0001) and use of hormonal therapy (p<0.0001). The number of locoregional failures, distant failures and mortalities were not significantly different. No significant difference was present in 5 year locoregional recurrence free (96% vs 92%, p=0.3), disease free (75% vs 74%, p=0.7) and overall survival (78% vs 83%, p=0.2). On multivariate analysis, tumor size, nodal involvement and hormonal treatment were independent predictors of negative events. Conclusions: Breast conserving therapy has comparable outcomes for triple negative and non-triple negative breast cancers.

Cytoprotective role of vitamin E in porcine adipose-tissue-derived mesenchymal stem cells against hydrogen-peroxide-induced oxidative stress

Bhatti, Fazal Ur Rehman,Kim, Song Ja,Yi, Ae-Kyung,Hasty, Karen A.,Cho, Hongsik Springer-Verlag 2018 Cell and tissue research Vol.374 No.1

Comparison between Early and Late Onset Breast Cancer in Pakistani Women Undergoing Breast Conservative Therapy: is There any Difference?

Bhatti, Abu Bakar Hafeez,Jamshed, Aarif,Khan, Amina,Siddiqui, Neelam,Muzaffar, Nargis,Shah, Mazhar Ali Asian Pacific Journal of Cancer Prevention 2014 Asian Pacific journal of cancer prevention Vol.15 No.13

Background: Early onset breast cancer is associated with poor outcomes but variable results have been reported. It is a significant problem in Pakistani women but remains under reported. Breast conservation plays an important role in surgical management of this younger patient group. The objective of this study was to determine the outcome of breast conservative therapy in patients with early onset breast cancer in our population and compare it with their older counterparts. Materials and Methods: A review of patients with invasive breast cancer who underwent breast conservation surgery at Shaukat Khanum Cancer Hospital from 1997 to 2009 was performed. Patients were divided into two groups i.e. Group I age ${\leq}40$ and Group II >40 years. A total of 401 patients with breast cancer were identified in Group I and 405 patients in Group II. Demographics, histopathological findings and receptor status of the two groups were compared. The Chi square test was used for categorical variables. Outcome was assessed on basis of 10 year locoregional recurrence free survival (LRRFS), disease free survival (DFS) and overall survival (OS). For survival analysis Kaplan Meier curves were used and significance was determined using the Log rank test. Cox regression was applied for multivariate analysis. Results: Median follow up was 4.31 (0.1-15.5) years. Median age at presentation was 34.6 years (17-40) and 51.9 years (41-82) for the two groups. Groups were significantly different from each other with respect to grade, receptor status, tumor stage and use of neoadjuvant therapy. No significant difference was present between the two groups for estimated 10 year LRRFS (86% vs 95%) (p=0.1), DFS (70% vs 70%) (p=0.5) and OS (75% vs 63%) (p=0.1). On multivariate analysis, tumor stage was an independent predictor of LRRFS, DFS and OS. Conclusions: Early onset breast cancer is associated with a distinct biology but does not lead to poorer outcomes in our population.

Metal oxide catalyst-aided solvent regeneration: A promising method to economize post-combustion CO₂ capture process

Bhatti, Umair H.,Sivanesan, Dharmalingam,Lim, Dae Ho,Nam, Sung Chan,Park, Sungyoul,Baek, Il Hyun Elsevier 2018 Journal of the Taiwan Institute of Chemical Engine Vol.93 No.-

<P><B>Abstract</B></P> <P>Despite the in-depth understanding of the amine-based post-combustion CO<SUB>2</SUB> capture technique gained by research efforts made over the decades, its large-scale practicality is hindered by extensive energy input in desorption and solvent degradation issues. The most thoroughly studied alkanolamine solvent, monoethanolamine (MEA), is still unable to capture a significant portion of CO<SUB>2</SUB> emissions at a bearable economic penalty, owing to these serious drawbacks. Herein, we demonstrate catalytic regeneration of MEA solvent with five commercially available metal oxide catalysts ̶ Ag<SUB>2</SUB>O, Nb<SUB>2</SUB>O<SUB>5</SUB>, NiO, CuO, and MnO<SUB>2</SUB> which would render this process suitable for achieving a bearable penalty. CO<SUB>2</SUB>-rich MEA solvent with an initial loading of 0.50 mol CO<SUB>2</SUB>/mol MEA was used in this study. A temperature range of interest was selected to perform the experiments in order to identify the optimal operating temperature for each of the catalysts used in this study. The results show that all of the catalysts used in this study improve the MEA regeneration where Ag<SUB>2</SUB>O presents the best regeneration performance followed by Nb<SUB>2</SUB>O<SUB>5</SUB> by desorbing up to 3.6 and 2.5 times greater CO<SUB>2</SUB> amounts with faster desorption rates, respectively. Overall, the results show that the MEA solvent can be regenerated at temperature as low as 80 °C, and hence a significant reduction in heat requirement for solvent regeneration is possible. Besides, at this temperature, thermal degradation of the solvent can be avoided completely. Furthermore, as a considerable improvement in the CO<SUB>2</SUB> desorption rate and cyclic capacity is achieved by the catalytic regeneration process, the size of the stripper and the solvent circulation rate can be reduced, which will decrease the capital and operating cost as well.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A promising metal oxide catalyst-aided MEA solvent regeneration technique is presented. </LI> <LI> With catalyst, MEA solvent can be regenerated at temperatures as low as 80 °C. </LI> <LI> Performance of the catalyst depends on acid sites and metal geometry. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Spatial correlation based analysis of soft combination and user selection algorithm for cooperative spectrum sensing

Bhatti, Dost Muhammad Saqib,Nam, Haewoon IET 2017 IET Communications Vol.11 No.1

<P>This study presents an analytical method that shows how spatial correlation degrades the overall performance of cooperative spectrum sensing. In a cooperative spectrum sensing, where all secondary users (SUs) report their sensing information to the fusion centre (FC), sensing information is correlated for closely located users due to the similar surrounding environment. Considering the soft combining at the FC, this study shows how detection performance of correlated SUs is different from uncorrelated SUs. Furthermore, an algorithm is proposed which selects best uncorrelated SUs among all SUs of the network based on received power to the FC from SUs. The simulation results confirm the performance analysis of cooperative spectrum sensing with spatial correlation on the sensing data.</P>

Can Induction Chemotherapy before Concurrent Chemoradiation Impact Circumferential Resection Margin Positivity and Survival in Low Rectal Cancers?

Bhatti, Abu Bakar Hafeez,Waheed, Anum,Hafeez, Aqsa,Akbar, Ali,Syed, Aamir Ali,Khattak, Shahid,Kazmi, Ather Saeed Asian Pacific Journal of Cancer Prevention 2015 Asian Pacific journal of cancer prevention Vol.16 No.7

Background: Distance from anal verge and abdominoperineal resection are risk factors for circumferential resection margin (CRM) positivity in rectal cancer. Induction chemotherapy (IC) before concurrent chemoradiation (CRT) has emerged as a new treatment modification. Impact of IC before concurrent CRT on CRM positivity in low rectal cancer remains to be independently studied. The objective of this study was to determine CRM positivity in low rectal cancer, with and without prior IC, and to identify predictors of disease free and overall survival. Materials and Methods: Patients who underwent surgery for rectal cancer between 2005 and 2011 were retrospectively reviewed and divided into two groups. Group 1 received IC before CRT and Group 2 did not. Demographics, clinicopathological variables and CRM status were compared. Actuarial 5 year disease free survival (DFS), overall survival (OS) and independent predictors of survival were determined. Results: Patients in the IC group presented with advanced stage (Stage 3=89.2% versus 75.4%) (P=0.02) but a high rate of total mesorectal excision (TME) (100% versus 93.4%) (P=0.01) and sphincter preservation surgery (54.9 % versus 22.9%) (P=0.001). Patients with low rectal cancer who received IC had a significantly low positive CRM rate (9.2% versus 34%) (P=0.002). Actuarial 5 year DFS in IC and no IC groups were 39% and 43% (P=0.9) and 5 year OS were 70% and 47% (P=0.003). Pathological tumor size [HR: 2.2, CI: 1.1-4.5, P=0.01] and nodal involvement [HR: 2, CI: 1.08-4, P=0.02] were independent predictors of relapse while pathological nodal involvement [HR: 2.6, CI: 1.3-4.9, P=0.003] and IC [HR: 0.7, CI: 0.5-0.9, P=0.02] were independent predictors of death. Conclusions: In low rectal cancer, induction chemotherapy before CRT may significantly decrease CRM positivity and improve 5 year overall survival.

Clinical Profile, Treatment and Survival Outcome of Testicular Tumors: A Pakistani Perspective

Bhatti, Abu Bakar Hafeez,Ahmed, Irfan,Ghauri, Rashid Khan,Saeed, Qamar,Mir, Khurram Asian Pacific Journal of Cancer Prevention 2014 Asian Pacific journal of cancer prevention Vol.15 No.1

Background: Testicular cancer management is considered a marvel of modern science with excellent treatment results. Pakistan has a distinct ethnic variation and geographic distribution but data regarding clinical presentation of testicular tumors and their management is under reported. The objective of this study was to determine clinical profile, treatment modalities and survival outcome of testicular tumors in the Pakistani population. Materials and Methods: A retrospective review of patients who received treatment for testicular cancer at Shaukat Khanum Cancer Hospital from January 2009 to December 2012 was performed. Patient demographics, clinical features at presentation and treatment modalities were assessed. For categorical variables chi square test was used. Survival was calculated using Kaplan Meier survival curves and Log rank test was employed to determine significance. Results: The most common tumor was mixed germ cell tumor in 49% patients. For all tumor variants except seminoma, stage III was the most common clinical stage at presentation. Majority of patients with non seminomatous germ cell tumors presented in the15-30 year age group as compared to seminoma which was most prevalent in the 30-40 year age group. Orchiectomy followed by chemotherapy was the most common treatment modality in 80% patients. Expected 5 year survival for seminomas and non-seminomatous germ cell tumors was 96% and 90% respectively which was not significantly different (p=0.2). Conclusions: Despite a distinct clinical profile of testicular tumors in Pakistani population, survival is comparable with published reports.