Browsing by Author "Shiv Kumar"

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A novel Raman spectroscopic approach to identify polymorphism in leflunomide: A combined experimental and theoretical study
(John Wiley and Sons Ltd, 2016) Poornima Sharma; Debraj Gangopadhyay; Sima Umrao; Shiv Kumar; A.K. Ghosh; P.C. Mishra; Ranjan K. Singh
Polymorphism is an important characteristic which affects the activity, solubility and other physical properties of a compound and can be induced by varying temperature, pressure and solvent. The presence and conversion of α to β polymorphic forms of an anti-rheumatic drug leflunomide have been studied by temperature-dependent and in situ Raman observations. Both α and β polymorphs were found to co-exist in the temperature interval 367-372 K. The α form alone exists below 367 K and the β form alone above 373 K. The C=O stretching band clearly demonstrates the α → β conversion because of breaking of N-H···O bond and formation of N-H···N bond. On cooling the Raman spectra suggest the irreversibility of this conversion. Thermodynamic stability, crystal parameters and surface morphology of both forms in the leflunomide powder used for the present study have been verified by differential scanning calorimetry, X-ray powder diffraction and scanning electron microscopy. © 2015 John Wiley & Sons, Ltd.
Anomalous Hall effect in Cu doped Bi2Te3 topological insulator
(Institute of Physics Publishing, 2020) Abhishek Singh; Shiv Kumar; Mahima Singh; Prajyoti Singh; Rahul Singh; Vinod K Gangwar; Archana Lakhani; Swapnil Patil; Eike F Schwier; Takeshi Matsumura; K. Shimada; A.K. Ghosh; Sandip Chatterjee
The angle resolved photo-emission spectroscopy (ARPES) study and magneto-transport properties of Bi2CuxTe3-x have been investigated. ARPES study indicates the clear existence of surface states in the as-prepared samples. The estimated bandgap from ARPES is found to be ∼5 meV and 16 meV respectively for x = 0.03 and x = 0.15 samples. Presence of larger Cu concentration (x = 0.15) introduces magnetic ordering. Observed non-linearity in the Hall data is due to the existence of anomalous Hall effect which can be attributed to the 2D transport. The observed magneto-transport features might be related to the surface carriers which is confirmed by ARPES study. © 2020 IOP Publishing Ltd.
Becoming Dalit Women’s Voice: Engaging with Self-reflective Narrative in Bama’s Karukku
(SAGE Publications Inc., 2022) Shiv Kumar
Dalit writings are considered to be centred on the issue of identity politics. Most analysis rests on their claim of identity as fixed and static. They ignore an embedded process of various spatial implications, characters’ interaction with it, and a self-reflexive narrative gaze that most of the prominent Dalit writers present through their autobiographical narratives. Concentration on these concepts provides a fresh perspective to critically analyse Dalit writings and presents a different understanding of identity formation. This article proposes to unearth this process through a reading of Bama’s Karukku (2012), in English translation. It attempts to establish that identity formation in Dalit writings is a process that is based on various kinds of spatial experiences that could be divided into three stages of development. This process culminates in transforming a character into a politically conscious Dalit figure. Also, this article attempts to chart a character’s development that corroborates to body’s spatial-cultural location and its response to/within that space. It is an attempt to understand various spatial ramifications that the character experiences in an attempt to forge an identity outside the traditional definition. © 2022 Indian Institute of Management, Ahmedabad.
c(RGDfK) anchored surface manipulated liposome for tumor-targeted tyrosine kinase inhibitor (TKI) delivery to potentiate liver anticancer activity
(Elsevier B.V., 2023) Payal Deepak; Praveen Kumar; Dilip Kumar Arya; Prashant Pandey; Shiv Kumar; Bishnu Prasad Parida; Gopeshwar Narayan; Sanjay Singh; Paruvathanahalli Siddalingam Rajinikanth
Current anticancer drug research includes tumor-targeted administration as a critical component because it is the best strategy to boost efficacy and decrease toxicity. Low drug concentration in cancer cells, nonspecific distribution, rapid clearance, multiple drug resistance, severe side effects, and other factors contribute to the disappointing results of traditional chemotherapy. As an innovative technique of treatments for hepatocellular carcinoma (HCC) in recent years, nanocarrier-mediated targeted drug delivery systems can overcome the aforesaid limitations via enhanced permeability and retention effect (EPR) and active targeting. Epidermal growth factor receptor (EGFR) inhibitor Gefitinib (Gefi) has dramatic effects on hepatocellular carcinoma. Herein, we developed and assessed an αvβ3 integrin receptor targeted c(RGDfK) surface modified liposomes for better targeting selectivity and therapeutic efficacy of Gefi on HCC cells. The conventional and modified Gefi loaded liposomes, i.e., denoted as Gefi-L and Gefi-c(RGDfK)-L, respectively, were prepared through the ethanol injection method and optimized via Box Behnken design (BBD). The FTIR and 1H NMR spectroscopy verified that the c(RGDfK) pentapeptides had formed an amide bond with the liposome surface. In addition, the particle size, Polydispersity index, zeta potential, encapsulation efficiency, and in-vitro Gefi release of the Gefi-L and Gefi-c(RGDfK)-L were measured and analyzed. As indicated by the MTT assay on HepG2 cells, Gefi-c(RGDfK)-L displayed considerably higher cytotoxicity than Gefi-L or Gefi alone. Throughout the incubation period, HepG2 cells took up significantly more Gefi-c(RGDfK)-L than Gefi-L. According to the in vivo biodistribution analysis, Gefi-c(RGDfK)-L accumulated more strongly at the tumor site than Gefi-L and free Gefi. Furthermore, HCC-bearing rats treated with Gefi-c(RGDfK)-L showed a substantial drop in liver marker enzymes (alanine transaminase, alkaline phosphatase, aspartate transaminase, and total bilirubin levels) compared to the disease control group. Gefi-c(RGDfK)-L suppresses tumour growth more effectively than Gefi-L and free Gefi, according to an in vivo analysis of their anticancer activities. Thus, c(RGDfK)-surface modified liposomes, i.e., Gefi-c(RGDfK)-L may serve as an efficient carrier for the targeted delivery of anticancer drugs. © 2023 Elsevier B.V.
Coexistence of Kondo effect and non trivial Berry phase in Gd doped Bi2Se3: an ARPES and magneto-transport study
(Institute of Physics, 2025) Swayangsiddha Ghosh; Rahul Kunwar Singh; Srishti Dixit; Shiv Kumar; Yogendra Kumar; Kenya Shimada; Anup Kumar Ghosh; Archana Lakhani; Sandip Chatterjee
The presence of magnetic impurities in topological insulators can disrupt their time reversal symmetry and lead to the emergence of an energy gap. This study delves into the energy band structure and the Kondo effect through the introduction of Gadolinium (Gd) magnetic perturbations (at levels of x = 0.1 , 0.16 ) into a pure Bi2Se3 single crystal. In the case of the Bi1.9Gd0.1Se3 (5%) single crystal, the Kondo effect becomes observable at temperatures below 50 K. However, the unaltered parent and Bi1.84Gd0.16Se3 (8%) exhibit typical metallic behavior. The pure sample displays the highest magnetoresistance (MR) of around 225% and demonstrates quantum oscillations driven by a nontrivial berry phase. The sample doped with 5% Gd undergoes a transition from negative MR to positive MR due to a presence of mixed magnetic state resulting from the opening of a gap at the Dirac point. This gap opening is confirmed through angle-resolved photoemission spectroscopy (ARPES) measurements. The comparison of the parameters obtained from the SdH and ARPES measurements, the reduction in the k F values in the magnetotransport measurements is likely due to the band bending induced by the Schottky barrier. Thermoelectric properties are assessed across all prepared samples. The undoped sample displays the highest Seebeck coefficient and power factor values of − 398.02 μ V K − 1 and 6.83 mW mK − 2 , respectively, at room temperature. These values are notably high for thermoelectric applications at room temperature. © 2025 IOP Publishing Ltd. All rights, including for text and data mining, AI training, and similar technologies, are reserved.
Correlation between changeover from weak antilocalization (WAL) to weak localization (WL) and positive to negative magnetoresistance in S-doped Bi1.5Sb0.5Te1.3Se1.7
(American Institute of Physics Inc., 2022) Mahima Singh; Labanya Ghosh; Vinod K. Gangwar; Yogendra Kumar; Debarati Pal; P. Shahi; Shiv Kumar; Sudip Mukherjee; K. Shimada; Sandip Chatterjee
The magneto-transport and angle-resolved photoelectron spectroscopy (ARPES) of the S-doped Bi1.5Sb0.5Te1.3Se1.7 system have been investigated. Both the positive magnetoresistance (pMR) and negative magnetoresistance (nMR) under a perpendicular magnetic field as well as a changeover from weak antilocalization (WAL) to weak localization (WL) are observed. The interplay between pMR and nMR is elucidated in terms of the dephasing and spin-orbit scattering time scales. The topological surface state bands have been explored using ARPES. © 2022 Author(s).
Defect induced ferromagnetic ordering and room temperature negative magnetoresistance in MoTeP
(NLM (Medline), 2021) Debarati Pal; Shiv Kumar; Prashant Shahi; Sambhab Dan; Abhineet Verma; Vinod K. Gangwar; Mahima Singh; Sujoy Chakravarty; Yoshiya Uwatoko; Satyen Saha; Swapnil Patil; Sandip Chatterjee
The magneto-transport, magnetization and theoretical electronic-structure have been investigated on type-II Weyl semimetallic MoTeP. The ferromagnetic ordering is observed in the studied sample and it has been shown that the observed magnetic ordering is due to the defect states. It has also been demonstrated that the presence of ferromagnetic ordering in effect suppresses the magnetoresistance (MR) significantly. Interestingly, a change-over from positive to negative MR is observed at higher temperature which has been attributed to the dominance of spin scattering suppression.
Effect of dilution of both A-and B-sites on the multiferroic properties of spinal Mott insulators
(Institute of Physics Publishing, 2015) Prashant Shahi; Rahul K. Singh; Rajesh K. Singh; Shiv Kumar; A. Tiwari; A. Tripathi; J. Saha; S. Patnaik; A.K. Ghosh; Sandip Chatterjee
The structural, magnetic, electrical and transport properties of FeV2O4, by doping Li and Cr ions in A and B sites, respectively, have been studied. Dilution of the A site by Li doping decreases the V-V distances which in effect increases the A-V coupling. This increased coupling enhances the ferrimagnetic ordering temperature and reduces the ferroelectric transition temperature. Furthermore, since Li is non-magnetic the A-V coupling is also decreased. The increase in A-V coupling dominates over the decrease in A-V coupling with Li doping. On the other hand, Cr doping increases the ferrimagnetic ordering temperature but does not alter the ferroelectric transition temperature, which is due to the fact that the polarization originates from the presence of almost non-substituted regions. © 2015 IOP Publishing Ltd.
Effects of Cr-doping on structural and optical properties of ZnO nanoparticles
(2013) Shiv Kumar; S. Chatterjee; Anup K. Ghosh
The synthesis method, structural and optical properties of sol-gel derived Zn1-xCrxO(0≤x≤0.06) nanoparticles has been reported. Rietveld refinement of X-ray diffraction pattern shows that all the samples are in single phase having wurtzite structure. It also confirms that Cr-ions are well incorporated into host lattice without changing the wurtzite structure of ZnO host lattice. X-ray diffraction and transmission electron microscopy observations showed the nanocrystalline nature of the samples. UV-Vis measurements show that the band gap is blue shifted in lower Cr-concentration and red shifted in higher Cr-concentration. This may be attributed due to the Burstein-Moss effect that prevails throughout this range of doping and sp-d exchange interaction which plays a significant role for higher Cr-concentration. © 2013 American Institute of Physics.
Electronic structure by X-ray absorption spectroscopy and observation of field induced unusually slow spin relaxation from magnetic properties in pyrochlore Eu2−xFexTi2O7
(Elsevier B.V., 2019) Arkadeb Pal; Surajit Ghosh; Shiv Kumar; Eike F. Schwier; Masahiro Sawada; Kenya Shimada; Mukul Gupta; D.M. Phase; A.K. Ghosh; Sandip Chatterjee
X-ray absorption spectroscopy (XAS) and magnetization of hybrid pyrochlore Eu2-xFexTi2O7 (EFTO) were investigated, where the rare earth Eu (4f) was replaced with transition metal Fe (3d) to introduce competing 4f-3d interactions. It is confirmed that the valence states of Eu and Fe ions are formally trivalent while that of Ti ions are tetravalent (3d0). The analysis yielded that the tetravalent Ti ions occupy octahedral sites with distorted Oh symmetry which is triggered by the presence of vacant 8a anionic site adjacent to TiO6 octahedra. Further study with Fe doping revealed that it essentially reduces the octahedral distortion by introducing anionic disorder (migration of 48f oxygen ions to 8a site). Analysis of O K edge XAS spectra further confirmed the Fe substitution causing the systematic change in the ligand (O2−) coordination of the Ti4+ cations. Interestingly, a new field induced transition at low temperature T* (4 K < T* < 8 K) associated with unusually slow spin relaxation was observed. The transition shifted towards higher temperatures both with increasing applied field and Fe concentration. However, the single ion spin freezing (Tf ∼ 35 K) appears to be largely suppressed with Fe substitution. Moreover, dc magnetization data showed rise of ferromagnetic contribution below 100 K. © 2018
Electronic structure study of wide band gap magnetic semiconductor (La0.6Pr0.4)0.65Ca0.35MnO3 nanocrystals in paramagnetic and ferromagnetic phases
(American Institute of Physics Inc., 2016) G.D. Dwivedi; Amish G. Joshi; Shiv Kumar; H. Chou; K.S. Yang; D.J. Jhong; W.L. Chan; A.K. Ghosh; Sandip Chatterjee
X-ray circular magnetic dichroism (XMCD), X-ray photoemission spectroscopy (XPS), and ultraviolet photoemission spectroscopy (UPS) techniques were used to study the electronic structure of nanocrystalline (La0.6Pr0.4)0.65Ca0.35MnO3 near Fermi-level. XMCD results indicate that Mn3+ and Mn4+ spins are aligned parallel to each other at 20 K. The low M-H hysteresis curve measured at 5 K confirms ferromagnetic ordering in the (La0.6Pr0.4)0.65Ca0.35MnO3 system. The low temperature valence band XPS indicates that coupling between Mn3d and O2p is enhanced and the electronic states near Fermi-level have been suppressed below TC. The valence band UPS also confirms the suppression of electronic states near Fermi-level below Curie temperature. UPS near Fermi-edge shows that the electronic states are almost absent below 0.5 eV (at 300 K) and 1 eV (at 115 K). This absence clearly demonstrates the existence of a wide band-gap in the system since, for hole-doped semiconductors, the Fermi-level resides just above the valence band maximum. © 2016 Author(s).
Enhanced multiferroic properties and magneto-dielectric effect analysis of La/Co modified BiFeO3
(Elsevier Ltd, 2017) S. Shankar; Manish Kumar; Shiv Kumar; O.P. Thakur; Anup K. Ghosh
Multiferroic BiFeO3(BFO), La/Co modified BiFeO3(BLFO/BLCFO) ceramics prepared by solid state reaction route were characterised and their magneto-dielectric properties were investigated. The phase purity of La/Co modified BFO ceramics was confirmed from powder X-ray diffraction studies and distortion observed in the lattice due to compression was found to be associated with polarization switching on La/Co co-substitution into BFO. An enhancement and stability in saturation magnetization with low coercive field (Hc≈ 400 Oe) has been achieved at room temperature in La/Co modified BFO samples. Dielectric and impedance measurements reveal the enhanced values of dielectric constant, real and imaginary part of impedance and modulus on account of modification by La/Co in BFO. The modulus studies confirm the presence of ionic polarization due to the co-substitution of La2+/Co3+ions and dominant grain effects in BLFO and BLCFO samples. The magneto-dielectric effect (% MDE) is found to be maximum value of 1.8 in magnitude at 8 kOe for BLFO-10%Co, and increases with increase in Co content in to BLFO. The substitution of Co into BLFO generates polarization at La and Fe layer, which provides the enhanced value of %MDE and stability in purity of BFO ceramic. © 2016 Elsevier B.V.
Enhancement in electrical and magnetic properties with Ti-doping in Bi0.5La0.5Fe0.5Mn0.5O3
(American Institute of Physics Inc., 2017) Rahul Singh; Prince Kumar Gupta; Shiv Kumar; Amish G. Joshi; A.K. Ghosh; S. Patil; Sandip Chatterjee
In this investigation, we have synthesized Bi0.5La0.5Fe05Mn0.5-xTixO3 (where x = 0 and 0.05) samples. The Rietveld refinement of X-ray diffraction (XRD) patterns shows that the systems crystallize in the orthorhombic phase with the Pnma space group. The observed Raman modes support the XRD results. The appearance of prominent A1-3 and weak E-2 modes in Bi0.5La0.5Fe0.5Mn0.45Ti0.05O3 indicates the presence of chemically more active Bi-O covalent bonds. Ferromagnetism of Bi0.5La0.5Fe0.5Mn0.5O3 is enhanced by Ti doping at the Mn-site, indicating that these particular samples might be interesting for device applications. © 2017 Author(s).
Global age-sex-specific mortality, life expectancy, and population estimates in 204 countries and territories and 811 subnational locations, 1950–2021, and the impact of the COVID-19 pandemic: a comprehensive demographic analysis for the Global Burden of Disease Study 2021
(Elsevier B.V., 2024) Austin E. Schumacher; Hmwe Hmwe Kyu; Amirali Aali; Cristiana Abbafati; Jaffar Abbas; Rouzbeh Abbasgholizadeh; Madineh Akram Abbasi; Mohammadreza Abbasian; Samar Abd ElHafeez; Michael Abdelmasseh; Sherief Abd-Elsalam; Ahmed Abdelwahab; Mohammad Abdollahi; Meriem Abdoun; Auwal Abdullahi; Ame Mehadi Abdurehman; Mesfin Abebe; Aidin Abedi; Armita Abedi; Tadesse M. Abegaz; Roberto Ariel Abeldaño Zuñiga; E.S. Abhilash; Olugbenga Olusola Abiodun; Richard Gyan Aboagye; Hassan Abolhassani; Mohamed Abouzid; Lucas Guimarães Abreu; Woldu Aberhe Abrha; Michael R.M. Abrigo; Dariush Abtahi; Samir Abu Rumeileh; Niveen M.E. Abu-Rmeileh; Salahdein Aburuz; Ahmed Abu-Zaid; Juan Manuel Acuna; Tim Adair; Isaac Yeboah Addo; Oladimeji M. Adebayo; Oyelola A. Adegboye; Victor Adekanmbi; Bashir Aden; Abiola Victor Adepoju; Charles Oluwaseun Adetunji; Temitayo Esther Adeyeoluwa; Olorunsola Israel Adeyomoye; Rishan Adha; Amin Adibi; Wirawan Adikusuma; Qorinah Estiningtyas Sakilah Adnani; Saryia Adra; Abel Afework; Aanuoluwapo Adeyimika Afolabi; Ali Afraz; Shadi Afyouni; Saira Afzal; Pradyumna Agasthi; Shahin Aghamiri; Antonella Agodi; Williams Agyemang-Duah; Bright Opoku Ahinkorah; Aqeel Ahmad; Danish Ahmad; Firdos Ahmad; Muayyad M. Ahmad; Tauseef Ahmad; Keivan Ahmadi; Amir Mahmoud Ahmadzade; Mohadese Ahmadzade; Ayman Ahmed; Haroon Ahmed; Luai A. Ahmed; Muktar Beshir Ahmed; Syed Anees Ahmed; Marjan Ajami; Budi Aji; Olufemi Ajumobi; Gizachew Taddesse Akalu; Essona Matatom Akara; Karolina Akinosoglou; Sreelatha Akkala; Samuel Akyirem; Hanadi Al Hamad; Syed Mahfuz Al Hasan; Ammar Al Homsi; Mohammad Al Qadire; Moein Ala; Timothy Olukunle Aladelusi; Tareq Mohammed Ali Al-Ahdal; Samer O. Alalalmeh; Ziyad Al-Aly; Khurshid Alam; Manjurul Alam; Zufishan Alam; Rasmieh Mustafa Al-Amer; Fahad Mashhour Alanezi; Turki M. Alanzi; Mohammed Albashtawy; Mohammad T. AlBataineh; Robert W. Aldridge; Sharifullah Alemi; Ayman Al-Eyadhy; Adel Ali Saeed Al-Gheethi; Khalid F. Alhabib; Fadwa Alhalaiqa Naji Alhalaiqa; Mohammed Khaled Al-Hanawi; Abid Ali; Akhtar Ali; Beriwan Abdulqadir Ali; Hassam Ali; Mohammed Usman Ali; Rafat Ali; Syed Shujait Shujait Ali; Zahid Ali; Shohreh Alian Samakkhah; Gianfranco Alicandro; Sheikh Mohammad Alif; Mohammad Aligol; Rasoul Alimi; Ahmednur Adem Aliyi; Adel Al-Jumaily; Syed Mohamed Aljunid; Wael Almahmeed; Sabah Al-Marwani; Sadeq Ali Ali Al-Maweri; Joseph Uy Almazan; Hesham M. Al-Mekhlafi; Omar Almidani; Mahmoud A. Alomari; Nivaldo Alonso; Jaber S. Alqahtani; Ahmed Yaseen Alqutaibi; Salman Khalifah Al-Sabah; Awais Altaf; Jaffar A. Al-Tawfiq; Khalid A. Altirkawi; Farrukh Jawad Alvi; Hassan Alwafi; Yaser Mohammed Al-Worafi; Hany Aly; Karem H. Alzoubi; Azmeraw T. Amare; Edward Kwabena Ameyaw; Abebe Feyissa Amhare; Tarek Tawfik Amin; Alireza Amindarolzarbi; Javad Aminian Dehkordi; Sohrab Amiri; Hubert Amu; Dickson A. Amugsi; Jimoh Amzat; Robert Ancuceanu; Deanna Anderlini; Pedro Prata Andrade; Catalina Liliana Andrei; Tudorel Andrei; Dhanalakshmi Angappan; Abhishek Anil; Afifa Anjum; Catherine M. Antony; Ernoiz Antriyandarti; Iyadunni Adesola Anuoluwa; Sumadi Lukman Anwar; Anayochukwu Edward Anyasodor; Seth Christopher Yaw Appiah; Muhammad Aqeel; Jalal Arabloo; Razman Arabzadeh Bahri; Morteza Arab-Zozani; Mosab Arafat; Ana Margarida Araújo; Aleksandr Y. Aravkin; Abdulfatai Aremu; Hany Ariffin; Timur Aripov; Benedetta Armocida; Mahwish Arooj; Anton A. Artamonov; Kurnia Dwi Artanti; Judie Arulappan; Idowu Thomas Aruleba; Raphael Taiwo Aruleba; Ashokan Arumugam; Malke Asaad; Saeed Asgary; Mubarek Yesse Ashemo; Muhammad Ashraf; Marvellous O. Asika; Seyyed Shamsadin Athari; Maha Moh'd Wahbi Atout; Alok Atreya; Sameh Attia; Avinash Aujayeb; Abolfazl Avan; Adedapo Wasiu Awotidebe; Beatriz Paulina Ayala Quintanilla; Martin Amogre Ayanore; Getnet Melaku Ayele; Jose L. Ayuso-Mateos; Seyed Mohammad Ayyoubzadeh; Sina Azadnajafabad; Gulrez Shah Azhar; Shahkaar Aziz; Ahmed Y. Azzam; Mina Babashahi; Abraham Samuel Babu; Muhammad Badar; Alaa Badawi; Ashish D. Badiye; Soroush Baghdadi; Nasser Bagheri; Sara Bagherieh; Sulaiman Bah; Saeed Bahadorikhalili; Jianjun Bai; Ruhai Bai; Jennifer L. Baker; Shankar M. Bakkannavar; Abdulaziz T. Bako; Senthilkumar Balakrishnan; Saliu A. Balogun; Ovidiu Constantin Baltatu; Kiran Bam; Maciej Banach; Soham Bandyopadhyay; Biswajit Banik; Palash Chandra Banik; Hansi Bansal; Shirin Barati; Martina Barchitta; Mainak Bardhan; Suzanne Lyn Barker-Collo; Francesco Barone-Adesi; Hiba Jawdat Barqawi; Ronald D. Barr; Lope H. Barrero; Zarrin Basharat; Asma'u I.J. Bashir; Hameed Akande Bashiru; Pritish Baskaran; Buddha Basnyat; Quique Bassat; João Diogo Basso; Saurav Basu; Kavita Batra; Ravi Batra; Bernhard T. Baune; Mohsen Bayati; Nebiyou Simegnew Bayileyegn; Thomas Beaney; Neeraj Bedi; Tahmina Begum; Emad Behboudi; Amir Hossein Behnoush; Maryam Beiranvand; Diana Fernanda Bejarano Ramirez; Uzma Iqbal Belgaumi; Michelle L. Bell; Aminu K. Bello; Muhammad Bashir Bello; Olorunjuwon Omolaja Bello; Luis Belo; Apostolos Beloukas; Salaheddine Bendak; Derrick A. Bennett; Isabela M. Bensenor; Habib Benzian; Zombor Berezvai; Adam E. Berman; Amiel Nazer C. Bermudez; Paulo J.G. Bettencourt; Habtamu B. Beyene; Kebede A. Beyene; Devidas S. Bhagat; Akshaya Srikanth Bhagavathula; Neeraj Bhala; Ashish Bhalla; Dinesh Bhandari; Nikha Bhardwaj; Pankaj Bhardwaj; Prarthna V. Bhardwaj; Ashish Bhargava; Sonu Bhaskar; Vivek Bhat; Gurjit Kaur Bhatti; Jasvinder Singh Bhatti; Manpreet S. Bhatti; Rajbir Bhatti; Zulfiqar A. Bhutta; Boris Bikbov; Nada Binmadi; Bagas Suryo Bintoro; Antonio Biondi; Catherine Bisignano; Francesca Bisulli; Atanu Biswas; Raaj Kishore Biswas; Saeid Bitaraf; Tone Bjørge; Archie Bleyer; Mary Sefa Boampong; Virginia Bodolica; Aadam Olalekan Bodunrin; Obasanjo Afolabi Bolarinwa; Milad Bonakdar Hashemi; Aime Bonny; Kaustubh Bora; Berrak Bora Basara; Safiya Bala Borodo; Rohan Borschmann; Alejandro Botero Carvajal; Souad Bouaoud; Sofiane Boudalia; Edward J. Boyko; Nicola Luigi Bragazzi; Dejana Braithwaite; Hermann Brenner; Gabrielle Britton; Annie J. Browne; Andre R. Brunoni; Norma B. Bulamu; Lemma N. Bulto; Danilo Buonsenso; Katrin Burkart; Richard A. Burns; Sharath Burugina Nagaraja; Reinhard Busse; Yasser Bustanji; Zahid A. Butt; Florentino Luciano Caetano Dos Santos; Tianji Cai; Daniela Calina; Luis Alberto Cámera; Luciana Aparecida Campos; Ismael R. Campos-Nonato; Chao Cao; Carlos Alberto Cardenas; Rosario Cárdenas; Sinclair Carr; Giulia Carreras; Juan J. Carrero; Andrea Carugno; Felix Carvalho; Márcia Carvalho; Joao Mauricio Castaldelli-Maia; Carlos A. Castañeda-Orjuela; Giulio Castelpietra; Ferrán Catalá-López; Alberico L. Catapano; Maria Sofia Cattaruzza; Arthur Caye; Christopher R. Cederroth; Francieli Cembranel; Muthia Cenderadewi; Kelly M. Cercy; Ester Cerin; Muge Cevik; Pamela R. Chacón-Uscamaita; Yaacoub Chahine; Chiranjib Chakraborty; Jeffrey Shi Kai Chan; Chin-Kuo Chang; Periklis Charalampous; Jaykaran Charan; Vijay Kumar Chattu; Victoria Chatzimavridou-Grigoriadou; Malizgani Paul Chavula; Huzaifa Ahmad Cheema; An-Tian Chen; Haowei Chen; Lingxiao Chen; Meng Xuan Chen; Simiao Chen; Nicolas Cherbuin; Derek S. Chew; Gerald Chi; Jesus Lorenzo Chirinos-Caceres; Abdulaal Chitheer; So Mi Jemma Cho; William C.S. Cho; Bryan Chong; Hitesh Chopra; Rahul Choudhary; Rajiv Chowdhury; Dinh-Toi Chu; Isaac Sunday Chukwu; Eric Chung; Eunice Chung; Sheng-Chia Chung; Karly I. Cini; Cain C.T. Clark; Kaleb Coberly; Alyssa Columbus; Haley Comfort; Joao Conde; Sara Conti; Paolo Angelo Cortesi; Vera Marisa Costa; Ewerton Cousin; Richard G. Cowden; Michael H. Criqui; Natália Cruz-Martins; Garland T. Culbreth; Patricia Cullen; Matthew Cunningham; Daniel da Silva E Silva; Sriharsha Dadana; Omid Dadras; Zhaoli Dai; Koustuv Dalal; Lachlan L. Dalli; Giovanni Damiani; Emanuele D'Amico; Sara Daneshvar; Aso Mohammad Darwesh; Jai K. Das; Saswati Das; Nihar Ranjan Dash; Mohsen Dashti; Claudio Alberto Dávila-Cervantes; Nicole Davis Weaver; Kairat Davletov; Diego De Leo; Aklilu Tamire Debele; Louisa Degenhardt; Reza Dehbandi; Lee Deitesfeld; Ivan Delgado-Enciso; Laura Delgado-Ortiz; Daniel Demant; Berecha Hundessa Demessa; Andreas K. Demetriades; Xinlei Deng; Edgar Denova-Gutiérrez; Kebede Deribe; Nikolaos Dervenis; Don C. Des Jarlais; Hardik Dineshbhai Desai; Rupak Desai; Keshab Deuba; Vinoth Gnana Chellaiyan Devanbu; Sourav Dey; Arkadeep Dhali; Kuldeep Dhama; Mandira Lamichhane Dhimal; Meghnath Dhimal; Sameer Dhingra; Diana Dias Da Silva; Daniel Diaz; Adriana Dima; Delaney D. Ding; M. Ashworth Dirac; Abhinav Dixit; Shilpi Gupta Dixit; Thanh Chi Do; Thao Huynh Phuong Do; Camila Bruneli Do Prado; Masoud Dodangeh; Klara Georgieva Dokova; Christiane Dolecek; E Ray Dorsey; Wendel Mombaque dos Santos; Rajkumar Doshi; Leila Doshmangir; Abdel Douiri; Robert Kokou Dowou; Tim Robert Driscoll; Haneil Larson Dsouza; John Dube; Samuel C. Dumith; Susanna J. Dunachie; Bruce B. Duncan; Andre Rodrigues Duraes; Senbagam Duraisamy; Oyewole Christopher Durojaiye; Sulagna Dutta; Paulina Agnieszka Dzianach; Arkadiusz Marian Dziedzic; Oluwakemi Ebenezer; Ejemai Eboreime; Alireza Ebrahimi; Chidiebere Peter Echieh; Abdelaziz Ed-Dra; Hisham Atan Edinur; David Edvardsson; Kristina Edvardsson; Defi Efendi; Ferry Efendi; Shayan Eghdami; Terje Andreas Eikemo; Ebrahim Eini; Michael Ekholuenetale; Emmanuel Ekpor; Temitope Cyrus Ekundayo; Rabie Adel El Arab; Doaa Abdel Wahab El Morsi; Maysaa El Sayed Zaki; Maha El Tantawi; Iffat Elbarazi; Noha Mousaad Elemam; Frank J. Elgar; Islam Y. Elgendy; Ghada Metwally Tawfik ElGohary; Hala Rashad Elhabashy; Muhammed Elhadi; Omar Abdelsadek Abdou Elmeligy; Mohammed Elshaer; Ibrahim Elsohaby; Amir Emami Zeydi; Mehdi Emamverdi; Theophilus I. Emeto; Luchuo Engelbert Bain; Ryenchindorj Erkhembayar; Tesfahun C. Eshetie; Sharareh Eskandarieh; Juan Espinosa-Montero; Kara Estep; Farshid Etaee; Ugochukwu Anthony Eze; Natalia Fabin; Adewale Oluwaseun Fadaka; Adeniyi Francis Fagbamigbe; Saman Fahimi; Luca Falzone; Carla Sofia E Sá Farinha; MoezAlIslam Ezzat Mahmoud Faris; Mohsen Farjoud Kouhanjani; Andre Faro; Hossein Farrokhpour; Ali Fatehizadeh; Hamed Fattahi; Nelsensius Klau Fauk; Pooria Fazeli; Valery L. Feigin; Ginenus Fekadu; Seyed-Mohammad Fereshtehnejad; Abdullah Hamid Feroze; Daniela Ferrante; Pietro Ferrara; Nuno Ferreira; Getahun Fetensa; Irina Filip; Florian Fischer; Joanne Flavel; Abraham D. Flaxman; Luisa S. Flor; Bobirca Teodor Florin; Morenike Oluwatoyin Folayan; Kristen Marie Foley; Artem Alekseevich Fomenkov; Lisa M. Force; Carla Fornari; Behzad Foroutan; Matteo Foschi; Kate Louise Francis; Richard Charles Franklin; Alberto Freitas; Joseph Friedman; Sara D. Friedman; Takeshi Fukumoto; John E. Fuller; Peter Andras Gaal; Muktar A. Gadanya; Santosh Gaihre; Abduzhappar Gaipov; Emmanuela Gakidou; Yaseen Galali; Nasrin Galehdar; Silvano Gallus; Quan Gan; Aravind P. Gandhi; Balasankar Ganesan; Jalaj Garg; Shuo-Yan Gau; Prem Gautam; Rupesh K. Gautam; Federica Gazzelloni; Miglas W. Gebregergis; Mesfin Gebrehiwot; Tesfay Brhane Gebremariam; Urge Gerema; Motuma Erena Getachew; Tamirat Getachew; Peter W. Gething; Mansour Ghafourifard; Sulmaz Ghahramani; Khalid Yaser Ghailan; Alireza Ghajar; Mohammad Javad Ghanbarnia; MohammadReza Ghasemi; Afsaneh Ghasemzadeh; Fariba Ghassemi; Ramy Mohamed Ghazy; Sailaja Ghimire; Asadollah Gholamian; Ali Gholamrezanezhad; Pooyan Ghorbani Vajargah; Ghozali Ghozali; Sherief Ghozy; Arun Digambarrao Ghuge; Alessandro Gialluisi; Ruth Margaret Gibson; Artyom Urievich Gil; Paramjit Singh Gill; Tiffany K. Gill; Richard F. Gillum; Themba G. Ginindza; Alem Girmay; James C. Glasbey; Elena V. Gnedovskaya; Laszlo Göbölös; Amit Goel; Mohamad Goldust; Mahaveer Golechha; Pouya Goleij; Arefeh Golestanfar; Davide Golinelli; Philimon N. Gona; Houman Goudarzi; Amir Hossein Goudarzian; Anmol Goyal; Scott Greenhalgh; Michal Grivna; Giovanni Guarducci; Mohammed Ibrahim Mohialdeen Gubari; Mesay Dechasa Gudeta; Avirup Guha; Stefano Guicciardi; Damitha Asanga Gunawardane; Sasidhar Gunturu; Cui Guo; Anish Kumar Gupta; Bhawna Gupta; Indarchand Ratanlal Gupta; Rajat Das Gupta; Sapna Gupta; Veer Bala Gupta; Vijai Kumar Gupta; Vivek Kumar Gupta; Reyna Alma Gutiérrez; Farrokh Habibzadeh; Parham Habibzadeh; Vladimir Hachinski; Mohammad Haddadi; Rasool Haddadi; Nils Haep; Adel Hajj Ali; Esam S. Halboub; Sobia Ahsan Halim; Brian J. Hall; Sebastian Haller; Rabih Halwani; Randah R. Hamadeh; Kanaan Hamagharib Abdullah; Samer Hamidi; Mohammad Hamiduzzaman; Ahmad Hammoud; Nasrin Hanifi; Graeme J. Hankey; Md Abdul Hannan; Md Nuruzzaman Haque; Harapan Harapan; Josep Maria Haro; Ahmed I. Hasaballah; Faizul Hasan; Ikramul Hasan; M Tasdik Hasan; Hamidreza Hasani; Mohammad Hasanian; Ali Hasanpour-Dehkordi; Abbas M. Hassan; Amr Hassan; Hossein Hassanian-Moghaddam; Soheil Hassanipour; Johannes Haubold; Rasmus J. Havmoeller; Simon I. Hay; Youssef Hbid; Jeffrey J. Hebert; Omar E. Hegazi; Golnaz Heidari; Mohammad Heidari; Mahsa Heidari-Foroozan; Reza Heidari-Soureshjani; Bartosz Helfer; Claudiu Herteliu; Hamed Hesami; Dineshani Hettiarachchi; Demisu Zenbaba Heyi; Kamal Hezam; Yuta Hiraike; Howard J. Hoffman; Ramesh Holla; Nobuyuki Horita; Md Belal Hossain; Md Mahbub Hossain; Sahadat Hossain; Mohammad-Salar Hosseini; Hassan Hosseinzadeh; Mehdi Hosseinzadeh; Mihaela Hostiuc; Sorin Hostiuc; Mohamed Hsairi; Vivian Chia-Rong Hsieh; Chengxi Hu; Junjie Huang; Md Nazmul Huda; Fernando N. Hugo; Michael Hultström; Javid Hussain; Salman Hussain; Nawfal R. Hussein; Le Duc Huy; Hong-Han Huynh; Bing-Fang Hwang; Segun Emmanuel Ibitoye; Oluwatope Olaniyi Idowu; Desta Ijo; Kevin S. Ikuta; Mehran Ilaghi; Olayinka Stephen Ilesanmi; Irena M. Ilic; Milena D. Ilic; Mustapha Immurana; Leeberk Raja Inbaraj; Arnaud Iradukunda; Farideh Iravanpour; Kenneth Chukwuemeka Iregbu; Md Rabiul Islam; Mohammad Mainul Islam; Sheikh Mohammed Shariful Islam; Farhad Islami; Nahlah Elkudssiah Ismail; Gaetano Isola; Masao Iwagami; Chidozie C.D. Iwu; Chinwe Juliana Iwu-Jaja; Mahalaxmi Iyer; Linda Merin; Jalil Jaafari; Louis Jacob; Kathryn H. Jacobsen; Farhad Jadidi-Niaragh; Morteza Jafarinia; Khushleen Jaggi; Kasra Jahankhani; Nader Jahanmehr; Haitham Jahrami; Akhil Jain; Nityanand Jain; Ammar Abdulrahman Jairoun; Mihajlo Jakovljevic; Reza Jalilzadeh Yengejeh; Elham Jamshidi; Chinmay T. Jani; Mark M. Janko; Abubakar Ibrahim Jatau; Sathish Kumar Jayapal; Shubha Jayaram; Jayakumar Jeganathan; Alelign Tasew Jema; Digisie Mequanint Jemere; Wonjeong Jeong; Anil K. Jha; Ravi Prakash Jha; John S. Ji; Heng Jiang; Yingzhao Jin; Yinzi Jin; Olatunji Johnson; Nabi Jomehzadeh; Darwin Phan Jones; Tamas Joo; Abel Joseph; Nitin Joseph; Charity Ehimwenma Joshua; Jacek Jerzy Jozwiak; Mikk Jürisson; Billingsley Kaambwa; Ali Kabir; Hannaneh Kabir; Zubair Kabir; Vidya Kadashetti; Farima Kahe; Pradnya Vishal Kakodkar; Rizwan Kalani; Leila R. Kalankesh; Feroze Kaliyadan; Sanjay Kalra; Ashwin Kamath; Arun Kamireddy; Thanigaivelan Kanagasabai; Himal Kandel; Edmund Wedam Kanmiki; Kehinde Kazeem Kanmodi; Rami S. Kantar; Neeti Kapoor; Mehrdad Karajizadeh; Behzad Karami Matin; Shama D. Karanth; Ibraheem M. Karaye; Asima Karim; Hanie Karimi; Salah Eddin Karimi; Arman Karimi Behnagh; Samad Karkhah; Ajit K. Karna; Faizan Zaffar Kashoo; Hengameh Kasraei; Nigussie Assefa Kassaw; Nicholas J. Kassebaum; Molly B. Kassel; Adarsh Katamreddy; Srinivasa Vittal Katikireddi; Patrick D.M.C. Katoto; Joonas H. Kauppila; Navjot Kaur; Neda Kaydi; Jeanne Françoise Kayibanda; Gbenga A. Kayode; Foad Kazemi; Sina Kazemian; Sara Kazeminia; Leila Keikavoosi-Arani; Cathleen Keller; John H. Kempen; Jessica A. Kerr; Emmanuelle Kesse-Guyot; Mohammad Keykhaei; Mohamad Mehdi Khadembashiri; Mohammad Amin Khadembashiri; Morteza Abdullatif Khafaie; Himanshu Khajuria; Mohammad Khalafi; Amirmohammad Khalaji; Nauman Khalid; Ibrahim A. Khalil; Faham Khamesipour; Asaduzzaman Khan; Gulfaraz Khan; Ikramullah Khan; Imteyaz A. Khan; Maseer Khan; Moien A.B. Khan; Taimoor Khan; Mahammed Ziauddin Khan Suheb; Shaghayegh Khanmohammadi; Khaled Khatab; Fatemeh Khatami; Armin Khavandegar; Hamid Reza Khayat Kashani; Khalid A. Kheirallah; Feriha Fatima Khidri; Elaheh Khodadoust; Moein Khormali; Mahmood Khosrowjerdi; Jagdish Khubchandani; Helda Khusun; Zemene Demelash Kifle; Grace Kim; Jihee Kim; Ruth W. Kimokoti; Kasey E. Kinzel; Girmay Tsegay Kiross; Adnan Kisa; Sezer Kisa; Juniper Boroka Kiss; Mika Kivimäki; Desmond Klu; Ann Kristin Skrindo Knudsen; Ali-Asghar Kolahi; Farzad Kompani; Gerbrand Koren; Soewarta Kosen; Karel Kostev; Ashwin Laxmikant Kotnis; Parvaiz A. Koul; Sindhura Lakshmi Koulmane Laxminarayana; Ai Koyanagi; Michael A. Kravchenko; Kewal Krishan; Hare Krishna; Vijay Krishnamoorthy; Yuvaraj Krishnamoorthy; Kris J. Krohn; Barthelemy Kuate Defo; Connor M. Kubeisy; Burcu Kucuk Bicer; Md Abdul Kuddus; Mohammed Kuddus; Ilari Kuitunen; Omar Kujan; Mukhtar Kulimbet; Vishnutheertha Kulkarni; Ashish Kumar; Harish Kumar; Nithin Kumar; Rahul Kumar; Shiv Kumar; Madhulata Kumari; Almagul Kurmanova; Om P. Kurmi; Asep Kusnali; Dian Kusuma; Tezer Kutluk; Ambily Kuttikkattu; Evans F. Kyei; Ilias Kyriopoulos; Carlo La Vecchia; Muhammad Awwal Ladan; Lucie Laflamme; Chandrakant Lahariya; Abdelilah Lahmar; Daphne Teck Ching Lai; Tri Laksono; Dharmesh Kumar Lal; Ratilal Lalloo; Tea Lallukka; Judit Lám; Demetris Lamnisos; Tuo Lan; Francesco Lanfranchi; Berthold Langguth; Van Charles Lansingh; Ariane Laplante-Lévesque; Bagher Larijani; Anders O. Larsson; Savita Lasrado; Kamaluddin Latief; Mahrukh Latif; Kaveh Latifinaibin; Paolo Lauriola; Long Khanh Dao Le; Nhi Huu Hanh Le; Thao Thi Thu Le; Trang Diep Thanh Le; Munjae Lee; Paul H. Lee; Sang-Woong Lee; Seung Won Lee; Wei-Chen Lee; Yo Han Lee; Samson Mideksa Legesse; James Leigh; Jacopo Lenzi; Elvynna Leong; Temesgen L. Lerango; Ming-Chieh Li; Wei Li; Xiaopan Li; Yichong Li; Zhihui Li; Massimo Libra; Virendra S. Ligade; Andrew Tiyamike Makhiringa Likaka; Lee-Ling Lim; Ro-Ting Lin; Shuzhi Lin; Vasileios-Arsenios Lioutas; Stefan Listl; Jue Liu; Simin Liu; Xiaofeng Liu; Katherine M. Livingstone; Erand Llanaj; Chun-Han Lo; Arianna Maever Loreche; László Lorenzovici; Mojgan Lotfi; Masoud Lotfizadeh; Rafael Lozano; Jailos Lubinda; Giancarlo Lucchetti; Alessandra Lugo; Raimundas Lunevicius
Background: Estimates of demographic metrics are crucial to assess levels and trends of population health outcomes. The profound impact of the COVID-19 pandemic on populations worldwide has underscored the need for timely estimates to understand this unprecedented event within the context of long-term population health trends. The Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2021 provides new demographic estimates for 204 countries and territories and 811 additional subnational locations from 1950 to 2021, with a particular emphasis on changes in mortality and life expectancy that occurred during the 2020–21 COVID-19 pandemic period. Methods: 22 223 data sources from vital registration, sample registration, surveys, censuses, and other sources were used to estimate mortality, with a subset of these sources used exclusively to estimate excess mortality due to the COVID-19 pandemic. 2026 data sources were used for population estimation. Additional sources were used to estimate migration; the effects of the HIV epidemic; and demographic discontinuities due to conflicts, famines, natural disasters, and pandemics, which are used as inputs for estimating mortality and population. Spatiotemporal Gaussian process regression (ST-GPR) was used to generate under-5 mortality rates, which synthesised 30 763 location-years of vital registration and sample registration data, 1365 surveys and censuses, and 80 other sources. ST-GPR was also used to estimate adult mortality (between ages 15 and 59 years) based on information from 31 642 location-years of vital registration and sample registration data, 355 surveys and censuses, and 24 other sources. Estimates of child and adult mortality rates were then used to generate life tables with a relational model life table system. For countries with large HIV epidemics, life tables were adjusted using independent estimates of HIV-specific mortality generated via an epidemiological analysis of HIV prevalence surveys, antenatal clinic serosurveillance, and other data sources. Excess mortality due to the COVID-19 pandemic in 2020 and 2021 was determined by subtracting observed all-cause mortality (adjusted for late registration and mortality anomalies) from the mortality expected in the absence of the pandemic. Expected mortality was calculated based on historical trends using an ensemble of models. In location-years where all-cause mortality data were unavailable, we estimated excess mortality rates using a regression model with covariates pertaining to the pandemic. Population size was computed using a Bayesian hierarchical cohort component model. Life expectancy was calculated using age-specific mortality rates and standard demographic methods. Uncertainty intervals (UIs) were calculated for every metric using the 25th and 975th ordered values from a 1000-draw posterior distribution. Findings: Global all-cause mortality followed two distinct patterns over the study period: age-standardised mortality rates declined between 1950 and 2019 (a 62·8% [95% UI 60·5–65·1] decline), and increased during the COVID-19 pandemic period (2020–21; 5·1% [0·9–9·6] increase). In contrast with the overall reverse in mortality trends during the pandemic period, child mortality continued to decline, with 4·66 million (3·98–5·50) global deaths in children younger than 5 years in 2021 compared with 5·21 million (4·50–6·01) in 2019. An estimated 131 million (126–137) people died globally from all causes in 2020 and 2021 combined, of which 15·9 million (14·7–17·2) were due to the COVID-19 pandemic (measured by excess mortality, which includes deaths directly due to SARS-CoV-2 infection and those indirectly due to other social, economic, or behavioural changes associated with the pandemic). Excess mortality rates exceeded 150 deaths per 100 000 population during at least one year of the pandemic in 80 countries and territories, whereas 20 nations had a negative excess mortality rate in 2020 or 2021, indicating that all-cause mortality in these countries was lower during the pandemic than expected based on historical trends. Between 1950 and 2021, global life expectancy at birth increased by 22·7 years (20·8–24·8), from 49·0 years (46·7–51·3) to 71·7 years (70·9–72·5). Global life expectancy at birth declined by 1·6 years (1·0–2·2) between 2019 and 2021, reversing historical trends. An increase in life expectancy was only observed in 32 (15·7%) of 204 countries and territories between 2019 and 2021. The global population reached 7·89 billion (7·67–8·13) people in 2021, by which time 56 of 204 countries and territories had peaked and subsequently populations have declined. The largest proportion of population growth between 2020 and 2021 was in sub-Saharan Africa (39·5% [28·4–52·7]) and south Asia (26·3% [9·0–44·7]). From 2000 to 2021, the ratio of the population aged 65 years and older to the population aged younger than 15 years increased in 188 (92·2%) of 204 nations. Interpretation: Global adult mortality rates markedly increased during the COVID-19 pandemic in 2020 and 2021, reversing past decreasing trends, while child mortality rates continued to decline, albeit more slowly than in earlier years. Although COVID-19 had a substantial impact on many demographic indicators during the first 2 years of the pandemic, overall global health progress over the 72 years evaluated has been profound, with considerable improvements in mortality and life expectancy. Additionally, we observed a deceleration of global population growth since 2017, despite steady or increasing growth in lower-income countries, combined with a continued global shift of population age structures towards older ages. These demographic changes will likely present future challenges to health systems, economies, and societies. The comprehensive demographic estimates reported here will enable researchers, policy makers, health practitioners, and other key stakeholders to better understand and address the profound changes that have occurred in the global health landscape following the first 2 years of the COVID-19 pandemic, and longer-term trends beyond the pandemic. Funding: Bill & Melinda Gates Foundation. © 2024 The Author(s). Published by Elsevier Ltd. This is an Open Access article under the CC BY 4.0 license
Imagined Ethnography and Cultural Strategies: A Study of Easterine Kire's Sky is My Father and Don't Run, My Love
(Aesthetics Media Services, 2022) Shiv Kumar
Stuart Hall, in his 1983 lectures states, "people have to have a language to speak about where they are and what other possible futures are available to them .These futures may not be real; if you try to concretize them immediately, you may find there is nothing there. But what is there, what is real, is the possibility of being someone else, of being in some other social space from the one in which you have already been placed." (Hall, 2016, p.205) The literature from Northeast India puts forward the issue of systematic erasure and structural exclusion [institutionalized through legal mechanisms like the Armed Forces Special Powers Act.] from the mainstream national imagination and literary space. Easterine Kire's primary agenda is to revitalize cultural practices that have been facing "historical elision." (Sarkar, 1997, p.359) This elision threatens the poly-ethnic, culturally vibrant, and tribal cultures by constructing and presenting the northeastern region of India as a conflict-ridden space. Situated within this ontology of existence, reality, and becoming, Easterine Kire's Don't Run, My Love (2017) and Sky is My Father: A Naga Village Remembered (2018) revive and revitalize the folktales and cultural practices to assert the cultural economy of the Naga tribes. Her writings represent a politically conscious positionality of the characters, context, and the plot to assert the culturally constituted identity through the revival of vibrant cultural practices and tribal epistemologies. © 2022 Aesthetics Media Services. All rights reserved.
Impedance spectroscopy and conductivity analysis of multiferroic BFO–BT solid solutions
(Elsevier B.V., 2017) Manish Kumar; S. Shankar; Brijmohan; Shiv Kumar; O.P. Thakur; Anup K. Ghosh
We report the investigations on the impedance and conductivity analysis of BiFeO3–BaTiO3 (BFO–BT) system prepared by solid state reaction route. The impedance studies reveal the presence of grain and grain boundary effects as confirmed from the single and double arc in the complex Cole–Cole plots. The impedance measurements confirm the temperature dependent electrical relaxation processes in the material for all compositions of BFO–BT attributing to the presence of immobile species at low temperature and defects/vacancies at higher temperatures. The BFO–BT systems exhibit non-Debye type of electric relaxation with concentration x=0.10, 0.15 and 0.30. The thermal variation of impedance parameters reflects a negative temperature coefficient of resistance behavior of the material analogous to semiconductor. The electrical conductivity studies obtained the activation energies related to grain contribution as 1.108, 0.795, 0.164 eV for (1−x)BFO–xBT (x=0.10, 0.15 and 0.30) and grain boundary as 0.708, 0.453 eV for (1−x)BFO–xBT (x=0.15 and 0.30) which is related to various factors including oxygen vacancies, mobility of defects, conduction via hopping and presence of same species responsible for conducting nature via grain and grain boundary. © 2016 Elsevier B.V.
Insight into the origin of ferromagnetism in Fe-doped ZnO diluted magnetic semiconductor nanocrystals: an EXFAS study of local structure
(Royal Society of Chemistry, 2015) Shiv Kumar; Nidhi Tiwari; S.N. Jha; S. Chatterjee; D. Bhattacharyya; N.K. Sahoo; Anup K. Ghosh
In this paper we have studied the structural, local structural and magnetic properties of sol-gel derived Zn1-xFexO (0 ≤ x ≤ 0.06) nanoparticles. The crystalline structure and crystallite size have been estimated by X-ray diffraction with Rietveld refinement and high-resolution transmission electron microscopy (HRTEM). Other structural and local structural properties have been studied by extended X-ray absorption fine structure (EXAFS)-, X-ray absorption near edge structure (XANES)- and Raman-analysis. Weak ferromagnetism is observed at room temperature and magnetization increases with increasing Fe-concentration. The oxygen vacancy assisted bound magnetic polarons (BMPs) and possibly the grain boundaries are responsible for this room temperature ferromagnetism. Variation of resistivity with temperature has also been studied. Appearance of ferromagnetism in ZnO: Fe nanoparticles may open the potential in bio-imaging and drug-delivery applications. © The Royal Society of Chemistry.
Investigation of multi-mode spin-phonon coupling and local B-site disorder in Pr2CoFeO6 by Raman spectroscopy and correlation with its electronic structure by XPS and XAS studies
(Institute of Physics Publishing, 2019) Arkadeb Pal; Surajit Ghosh; Amish G. Joshi; Shiv Kumar; Swapnil Patil; Prince K. Gupta; Prajyoti Singh; V.K. Gangwar; P. Prakash; Ranjan K. Singh; Eike F. Schwier; M. Sawada; K. Shimada; A.K. Ghosh; Amitabh Das; Sandip Chatterjee
Electronic structure of Pr2CoFeO6 (at 300 K) was investigated by x-ray photoemission spectroscopy (XPS) and x-ray absorption spectroscopy techniques. All three cations, i.e. Pr, Co and Fe were found to be trivalent in nature. XPS valance band analysis suggested the system to be insulating in nature. The analysis suggested that Co3+ ions exist in low spin state in the system. Moreover, Raman spectroscopy study indicated the random distribution of the B-site ions (Co/Fe) triggered by same charge states. In temperature-dependent Raman study, the relative heights of the two observed phonon modes exhibited anomalous behaviour near magnetic transition temperature TN ∼ 270 K, thus indicating towards interplay between spin and phonon degrees of freedom in the system. Furthermore, clear anomalous softening was observed below TN which confirmed the existence of strong spin-phonon coupling occurring for at least two phonon modes of the system. The line width analysis of the phonon modes essentially ruled out the role of magnetostriction effect in the observed phonon anomaly. The investigation of the lattice parameter variation across TN (obtained from the temperaturedependent neutron diffraction measurements) further confirmed the existence of the spin- phonon coupling. © 2019 IOP Publishing Ltd Printed in the UK.
Investigation of the physical properties of Fe:TiO2-diluted magnetic semiconductor nanoparticles
(Royal Society of Chemistry, 2017) Brijmohan Prajapati; Shiv Kumar; Manish Kumar; S. Chatterjee; Anup K. Ghosh
The structural, optical, magnetic, and electrical properties of sol-gel-derived Ti1-xFexO2 (0.00 ≤ x ≤ 0.05) nanoparticles were investigated. Rietveld refinement of the X-ray diffraction data and TEM measurements were carried out to analyze the crystalline structure and quality of all the samples. Raman spectroscopy revealed a decrease in intensity and broadening of the characteristics peaks of Fe-doped TiO2 with respect to those of the pristine sample, which signifies a structural distortion of the lattices. FT-IR, UV-vis, and PL spectroscopy were used to investigate the optical properties. Magnetic measurements showed a weak ferromagnetism at room temperature in both the pristine and Fe-doped TiO2 (x = 0, 0.02, and 0.05) nanoparticles. Temperature-dependent resistivity measurements showed the semiconducting nature of the samples and revealed that the thermally activated conduction (Arrhenius) mechanism is valid in the high-temperature region, whereas Mott variable range hopping (VRH) mechanism is valid in the low-temperature region. Dielectric properties of the samples were studied as a function of temperature in the frequency range of 1 kHz to 1 MHz. © 2017 The Royal Society of Chemistry.
Investigations on structural and optical properties of Al-modified ZnO nanoparticles
(Springer, 2020) Shiv Kumar; Manish Kumar; Arvind Kumar; Subhash Sharma; Prashant Shahi; Sandip Chatterjee; Anup Kumar Ghosh
The current studies are concentrated on the synthesis of Al-modified ZnO nanoparticles prepared through sol–gel method for their structural and optical properties. The wurtzite structure with single phase formation for all the samples was confirmed from the Rietveld analysis on XRD data. Nano-crystalline nature (having particle size (~ 10 to 30 nm)) of all the synthesized samples have been examined by XRD and TEM data. Optical properties were carried out from UV–Vis, FTIR and Raman spectroscopy techniques. FTIR and Raman analysis also confirms the wurtzite structure and tetrahedral configuration with coordination of oxygen ions nearby the zinc ions. The UV–Vis measurement confirms that the bandgap is blue-shifted and slow red shift for lower and higher Al-concentrations in ZnO, respectively. Visible emission spectra of PL confirms the photo generated holes with deep-level emission, which is ascribed to recombination of electrons intensely spellbound in oxygen vacancies and zinc interstitials. © 2020, Springer Science+Business Media, LLC, part of Springer Nature.