bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Supervisory Model for Emerging PhDs in Basic Medical Sciences on the African Continent: A Perspective
Authors: Owolabi Joshua Oladele 
Published: April 2021

Aim/Purpose: This article- a perspective, is an attempt to critically review the African scenario with respect to doctoral supervision for Basic Medical Sciences and proffer potential solutions in the form of a supervisory model.
Background: There is a need to develop supervisory models for emerging PhDs in Basic Medical Sciences [BMS] in Africa. There has been continuous evolutions and rapid advancements as further compounded by continuous sophistication in research tools, methods, and technologies. These have resulted in newer fields emerging from the traditional fields. A major fallout of this is a shortage or rather unavailability of supervisors to train younger scientists in these new fields. The available supervisors were mostly trained in a more traditional fields or in the context of the relatively traditional paradigm of scholarship. Thus, Africa currently, suffers from a lack of supervisory capacity to train younger scientists in the emerging fields of Basic Medical Sciences.
Methodology: This article is a perspective that included a narrative review of literature, critical appraisal of the current prevalent scenario, and proposition of a supervisory model. Relevant literature sources were considered. Effort was made to provide a practical supervisory model that might guide African doctoral schools to train doctoral candidates in emerging fields, leveraging on available resources while making strategic adaptions. It is important to note that this should be done in an evidence-based manner, hence standard practices were reviewed and considered.
Contribution: There is currently a paucity of data and information on doctoral scholarship and supervision in Africa. There is a need to conduct research on relevant subjects to provide further insight into the prevalent scenarios, the root cause of the problems and postulate potential solutions to the problems. This article presents a model that might employ effective, innovative, and practical approaches to address the current situation. Otherwise, lack of adequate supervisory capacity could contribute perpetually to impeding adequate advancements in BMS in Africa, through scholarship, particularly in line with global trends and current realities. The article proposes a collaborative model for supervising emerging and novel PhDs.
Growth and Yield Characteristics of Five Different Sweet Potato Varieties Grown in the Guinea Savanna Ecological Zone of Ghana
Authors: Ayimbire Abonuusum , Asumboya Gabriel , Atinga Christina Abi , Akazotiyele Richard , Marcellinus Bodieu 
Published: April 2021

Aim: To determine the growth characteristics of five sweet potato varieties on different soil types as well as how they each relates to tuber yield. This investigation will help guide farmers from resource-limited areas to select varieties that grow well in austere soils to produce good yield of tubers, thereby boosting global food security.
Study Design: Randomized complete block design (RCBD) with five treatments and three replications.
Place and Duration of Study: Experimental field of Bolgatanga Technical University for five months.
Methodology: Planting was done by inserting 10 cm length of each 30 cm long soft wood vine cutting into the soil, followed by watering. Five vine cuttings planted per ridge at a spacing of 60cm. Vine cuttings were transplanted in the same order on each ridge. There were 15 plants per treatment, so seventy-five (75) for the five treatments.
Results: Analysis of the soil showed sandy loamy soil with suitable pH of 6.05. The Orange flesh and Agric white varieties had the largest and smallest leaf areas of 177.76 cm2 and 110.74 cm2 respectively. Leaf area was positively correlated with root tuber mass in only the Red local variety (r = 0.026). Petiole length of the Orange flesh variety (19.08 cm) was significantly longer than that of the Agric white (13.55 cm, p = 0.02), Agric orange flesh (13.85 cm, p = 0.04), Red skin (11.84 cm, p = 0.00) and Red local (12.18 cm, p = 0.00) varieties. Petiole length was positively correlated with tuber yield in only the Orange flesh variety (r = 204). The Red skin (174.28 cm) and Red local (172.46 cm) varieties had the longest vines than all the rest, though not statistically significant (p = 0.241). Root tuber yield of the five varieties were Agric white (1.22 Kg), Agric orange flesh (1.40 Kg), Red skin (4.27 Kg), Red local (2.96 Kg) and Orange flesh (5.72 Kg), which were significantly different from each other (p=0.05).
Conclusion: The Orange flesh variety had the largest leaf area, longest petioles and the highest root tuber mass. On the other hand, the Agric white variety recorded the least Leaf area, Vine length and Tuber mass while the Red skin variety had the shortest Petioles.
Phytochemical Profiling and Antioxidant Activity of Aqueous Leaf Extract of Vitex negundo
Authors: Umamaheswari Govindarajan , Selvam Kuppusamy , Prakash Palanisamy 
Published: April 2021

Natural products from plants, animals and minerals are the basis for treating human diseases. The present investigation explains that the antioxidant potential of aqueous extract of vitex negundo leaves. Phytochemical constituents, total phenolic and flavanoid content of aqueous analysis and vitro methods such as 1,1-diphenyl-2picrylhydrazyl (DPPH), 2,2-azino-bis(3-ethylbenzthiazoline-6-sulphonic acid) (ABTS) radical scavenging assays and GC_MS studies are reported. In addition, TPC and TFC of the extract were evaluated. It was observed that the leaf extract total phenol (14.3 mg) and flavanoids (8.5 mg) Quercetin equivalent (Q/g) high level of Phenolic and flavonoid content that might have accounted for the strong activity observed ABTS 62% of inhibition µg/ mL almost equivalent to that of standard vitamin C and DPPH value of 66.32 µg/ mL almost equivalent to that of standard vitamin C results revealed that leaves of vitex negundo have Since this investigation is a preliminary study, a detailed study of the antioxidant mechanisms of specific phenol components is an absolute necessity. Many phytochemical constituents which may be responsible for many pharmacological activities.
Stretchable Mesh‐Patterned Organic Semiconducting Thin Films on Creased Elastomeric Substrates
Authors: Kim Seong Won , Park Sangsik , Lee Siyoung , Kim Daegun , Lee Giwon , Son Jonghyun , Cho Kilwon 
Published: April 2021

AbstractRecently, many researchers have tried to develop stretchable semiconducting thin films that can maintain their electrical performance under stretching. However, the fabrication processes have not been sufficiently practical and feasible to be used for soft electronics. Here, a stretchable high‐performance organic semiconducting thin film is fabricated by exploiting simultaneous patterning and pinning of a polymer semiconductor solution on an elastomeric substrate in which creasing‐instability has occurred. As a result, a mesh‐like polymer semiconducting thin film having vacant regions in the crease centers and surrounding crystalline regions near them can be fabricated. Due to the mesh‐like morphology and the percolated crystalline regions, the polymer semiconducting thin film shows superior stretchability and charge‐transport performance compared to the reference flat polymer thin film. When incorporated into organic thin‐film transistors, the DPP‐DTT polymer semiconducting thin film maintains its high field‐effect carrier mobility (0.53 ± 0.03 cm2 (V s)−1) under a strain ε of 80% and is highly stable under repeated stretching cycles at an ε of 50%.
High Yield Electrosynthesis of Hydrogen Peroxide from Water Using Electrospun CaSnO3@Carbon Fiber Membrane Catalysts with Abundant Oxygen Vacancy
Authors: Zhang Chaoqi , Lu Ruihu , Liu Chao , Yuan Ling , Wang Jing , Zhao Yan , Yu Chengzhong 
Published: April 2021

AbstractHydrogen peroxide (H2O2) production by electrochemical two‐electron water oxidation reaction (2e‐WOR) is a promising approach, where high‐performance electrocatalysts play critical roles. Here, the synthesis of nanostructured CaSnO3 confined in conductive carbon fiber membrane with abundant oxygen vacancy (OV) as a new generation of 2e‐WOR electrocatalyst is reported. The CaSnO3@carbon fiber membrane can be directly used as a self‐standing electrode, exhibiting a record‐high H2O2 production rate of 39.8 µmol cm−2 min−1 and a selectivity of ≈90% (at 2.9 V vs reversible hydrogen electrode). The CaSnO3@carbon fiber membrane design improves not only the electrical conductivity and stability of catalysts but also the inherent activity of CaSnO3. Density functional theory calculation further indicates the crucial role of OV in increasing the adsorption free energy toward oxygen intermediates associated with the competitive four‐electron water oxidation reaction pathway, thus enhancing the activity and selectivity of 2e‐WOR. The findings pave a new avenue to the rational design of electrocatalysts for H2O2 production from water.
Bipyridine Modified Conjugated Carbon Aerogels as a Platform for the Electrocatalysis of Oxygen Reduction Reaction
Authors: Peles‐Strahl Leigh , Zion Noam , Lori Oran , Levy Naomi , Bar Galit , Dahan Adi , Elbaz Lior 
Published: April 2021

AbstractAerogels offer a great platform for heterogeneous electrocatalysis owing to their high surface area and porosity. Atomically dispersed transition metal ions can be imbedded in these platforms at ultra‐high site density to make them catalytically active for various reactions. Herein, the synthesis of a new class of conjugated microporous organic aerogels that are used as covalent 3D frameworks for the electrocatalysis of oxygen reduction reaction (ORR) is reported. Modified aerogels functionalized with bipyridine ligands enable copper ion complexation in a single‐step synthesis. The aerogels’ structures are fully characterized using a wide array of spectroscopic and microscopic methods, and heat‐treated in order to make them electronically conductive. After heat treatment at 600 °C, the aerogels maintained their macrostructure and became active ORR catalysts in alkaline environment, showing high mass activity and ultra‐high site density.
Synthesis of 0D Manganese‐Based Organic–Inorganic Hybrid Perovskite and Its Application in Lead‐Free Red Light‐Emitting Diode
Authors: Yan Siyu , Tian Wanli , Chen Hua , Tang Kaixin , Lin Tingting , Zhong Gaoyu , Qiu Longzhen , Pan Xiaoyong , Wang Weizhi 
Published: April 2021

AbstractLead‐based perovskite light‐emitting diodes (PeLEDs) have exhibited excellent purity, high efficiency, and good brightness. In order to develop nontoxic, highly luminescent metal halide perovskite materials, tin, copper, germanium, zinc, bismuth, and other lead‐free perovskites have been developed. Here, a novel 0D manganese‐based (Mn‐based) organic–inorganic hybrid perovskite with the red emission located at 629 nm, high photoluminescence quantum yield of 80%, and millisecond level triplet lifetime is reported. When applied as the emissive layer in the PeLEDs, the maximum recording brightness of devices after optimization is 4700 cd m−2, and the peak external quantum efficiency is 9.8%. The half‐life of the device reaches 5.5 h at 5 V. The performance and stability of Mn‐based PeLEDs are one order of magnitude higher than those of other lead‐free PeLEDs. This work clearly shows that the Mn‐based perovskite will provide another route to fabricate stable and high‐performance lead‐free PeLEDs.
A Decade of Progress on Solid‐State Electrolytes for Secondary Batteries: Advances and Contributions
Authors: Sheng Ouwei , Jin Chengbin , Ding Xufen , Liu Tiefeng , Wan Yuehua , Liu Yujing , Nai Jianwei , Wang Yao , Liu Chuntai , Tao Xinyong 
Published: April 2021

AbstractCompared with conventional liquid batteries, all‐solid‐state batteries (ASSBs) show great promise for enabling higher safety in electric vehicles without compromising operational durability and range. As a key component of ASSBs, solid‐state electrolytes (SSEs) need high ionic conductivity and favorable interfacial compatibility between electrodes and SSEs. In the recent decade, numerous efforts have been devoted to SSE advancement and fruitful achievements have been made, particularly regarding metal anode‐oriented SSEs with high energy density. This review focuses on the historical process of SSEs employed in ASSBs. The new understanding and origins for the enhanced ionic conductivity and mechanical properties of SSEs are first summarized. As to the cathode/SSE interface, its decomposition mechanism and modification strategies are analyzed. As to the interfacial issues of SSEs with anodes, the mechanisms of dendrite formation and penetration into the SSEs are discussed in detail. Additionally, assisted by a library of big data sources, contributions are systematically highlighted from different countries, institutions, and corresponding authors to significantly advance SSE progress, and certain insights are provided into the underlying relationships between various items in a collective manner. Finally, current challenges and potential strategies are identified for the future development of SSEs in ASSBs.
High‐Q and Tailorable Fano Resonances in a One‐Dimensional Metal‐Optical Tamm State Structure: From a Narrowband Perfect Absorber to a Narrowband Perfect Reflector
Authors: Wang Zhiyu , Ho Ya‐Lun , Cao Tun , Yatsui Takashi , Delaunay Jean‐Jacques 
Published: April 2021

AbstractFano resonances giving rise to a rich variety of asymmetric spectral shapes have been investigated in optical nanostructures with multidimensional configurations. However, 1D nanostructure realizing Fano resonances with well‐controlled spectral shapes are yet to be demonstrated. Here, the authors present both numerically and experimentally a 1D nanostructure exhibiting rich Fano resonances induced by interference between a lossy background (continuum) provided by a metal thin film and a discrete optical Tamm state (OTS). A drastic change in the Fano line shape occurs from a narrowband perfect absorber into a narrowband perfect reflector by controlling the metal thin film. Independent from the metal‐related Fano profile, the OTS component determines the resonance frequency and guarantees a sharp resonance (with quality factors over 1000) on the flat mirror background. Taking advantage of its high‐Q property, the structure can be developed into a dispersion device with subnanometer spectral resolution, which even enables a direct imaging of spectral information of molecular fingerprint. The authors believe that this work not only demonstrates a planar nanostructure with versatile Fano resonances for various applications but also provides physical insights into how a metal thin film can induce and significantly affect the Fano resonances in 1D optical resonators.
Cellulose: A Contribution for the Zero e‐Waste Challenge
Authors: Nandy Suman , Goswami Sumita , Marques Ana , Gaspar Diana , Grey Paul , Cunha Inês , Nunes Daniela , Pimentel Ana , Igreja Rui , Barquinha Pedro , Pereira Luís , Fortunato Elvira , Martins Rodrigo 
Published: April 2021

AbstractThe world in the 21st century is confronted with multifaceted challenges against rapid climate change and continuous ecological disturbances caused by revolutionary socio‐economic developments, accelerated expansion of disposable electronic gadgets, and growing dependence on unrecyclable raw materials, among others. The ever‐increasing consumer demand for electronic devices is significantly contributing to the world's fastest‐growing waste stream, known as electronic waste (e‐waste), which is becoming an environmental threat at an alarming rate due to its toxic legacy. The ever‐shortening lifespan of smart technologies has created a “tsunami of e‐waste,” as the United Nations has characterized it, with 50 million tons accumulated each year, of which only 20% undergo formal e‐recycling. Therefore, the challenge of optimizing the current resources management models with an aim of improving the manufacturing processes and lifecycles of electronic devices, as well as building a circular economy, has become significantly prominent. Paper/cellulose, which covers a wide range of essential needs in everyday scenarios (from packaging to writing utilities), constitutes promising candidates for the effective achievement of a circular economy. Particularly, cellulose is revealed as an advantageous material for electronic applications because of its abundant availability, which contributes to its cost‐effectiveness, straightforward fabrication process, and high recyclability and reproducibility.
Tailoring Circular Dichroism for Simultaneous Control of Amplitude and Phase via Ohmic Dissipation Metasurface
Authors: Wang He , Jing Yao , Li Yongfeng , Huang Lingling , Feng Maochang , Yuan Qi , Bai Hui , Wang Jiafu , Zhang Jieqiu , Qu Shaobo 
Published: April 2021

AbstractCircular dichroism, as one of the exotic phenomena, derives from chirality biomolecules in nature, expressing differential absorption of spin angular momentum. The concept of dichroism has been migrated to the field of artificial materials and acquired adequate development. However, there is still a lack of a flexible strategy to tailor circular dichroism for providing another promising level to achieve spin‐selective multi‐dimensional manipulation of electromagnetic waves. In this work, a paradigm of reflective chiral metasurface is proposed to promote this aspect of exploration. By introducing loss resistors into the chiral meta‐atoms, the magnitude of differential absorption effect can be tailored by varying the corresponding resistance, leading to the variation of co‐polarization reflection amplitude. Combining with the Pancharatnam–Berry phases of chiral meta‐atom, both the reflective amplitude and phase are flexibly controlled in independent manners. Accordingly, the pattern of reflection fields can be theoretically shaped into arbitrary forms through Fourier transform in spatial domain. Here, metasurfaces for achieving rectangular‐shaped beam and complex‐amplitude hologram are demonstrated as two proofs‐of‐principle. Encouragingly, this effort provides an alternative approach for simultaneous control of amplitude and phase, which may pave a new route in the fields of beam‐forming technology and spin‐selective integrated systems.
Polarization‐Modulated Photovoltaic Effect at the Morphotropic Phase Boundary in Ferroelectric Ceramics
Authors: Wu Liyan , Burger Aaron M. , Bennett‐Jackson Andrew L. , Spanier Jonathan E. , Davies Peter K. 
Published: April 2021

AbstractFerroelectric materials, which exhibit switchable polarization, are potential candidates for photovoltaic applications owing to their intriguing charge carrier separation mechanism associated with polarization and breaking of inversion symmetry. To overcome the low photocurrent of ferroelectrics, extensive efforts have focused on reducing their bandgaps to increase the optical absorption of the solar spectrum and thus the power conversion efficiency. Here, a new avenue of enhancing photovoltaic performance via engineering the polarization across a morphotropic phase boundary (MPB) is reported. Tetragonal compositions in the vicinity of the MPB in a PbTiO3‐Bi(Ni1/2Ti1/2)O3 solid solution are shown to generate up to 3.6 kV cm−1 photoinduced electric field and 6.2 µA cm−2 short‐circuit photocurrent, multiple times higher than its pseudocubic counterpart under the same illumination conditions with excellent polarization retention. This enhancement allows the investigation of the correlation between the polarization switching and photovoltaic switching, which enables a controllable multistate photocurrent. Combined with a bandgap of 2.2 eV, this material exhibits a sizable photoresponse over a broad spectral range. These findings provide a new approach to improve the photovoltaic performance of ferroelectric materials and can expand their potential applications in optoelectronic devices.
Balancing Charge Extraction for Efficient Back‐Contact Perovskite Solar Cells by Using an Embedded Mesoscopic Architecture
Authors: Lin Xiongfeng , Lu Jianfeng , Raga Sonia. R. , McMeekin David P. , Ou Qingdong , Scully Andrew D. , Tan Boer , Chesman Anthony S. R. , Deng Siqi , Zhao Boya , Cheng Yi‐Bing , Bach Udo 
Published: April 2021

AbstractAs the performance of organic–inorganic halide perovskite solar cells approaches their practical limits, the use of back‐contact architectures, which eliminate parasitic light absorption, provides an effective route toward higher device efficiencies. However, a poor understanding of the underlying device physics has limited further performance improvements. Here a mesoporous charge‐transporting layer is introduced into quasi‐interdigitated back‐contact perovskite devices and the charge extraction behavior with an increased interfacial contact area is studied. The results show that the incorporation of a thin mesoporous titanium dioxide layer significantly shortens the charge‐transfer lifetime and results in more efficient and balanced charge extraction dynamics. A high short‐circuit current density of 21.3 mA cm–2 is achieved using a polycrystalline perovskite layer on a mesoscopic quasi‐interdigitated back‐contact electrode, a record for this type of device architecture.
Structural and quantitative evolution of organic matters in oil shale during two different retorting processes
Authors: Wang Dan , Liu Yunyi , Zhang Tao , Christopher Daniel Happy , Bature Nafiu Sadi , Fan Tianbo , Guo Hongfan 
Published: April 2021

AbstractIn this study, traditional strongly endothermic anaerobic retorting (AR) and relatively novel self‐heating retorting (SHR) processes for oil shale (OS) were investigated and compared in detail. These studies mainly involve the structural and quantitative evolution of organic matters in OS during retorting, including varieties of crystallite parameters, carbon framework structure, amounts of various structural carbons and toxic polycyclic aromatic hydrocarbons, and so on. The obtained results well elucidate some reaction pathways in AR and SHR as well as certain differences between the two retorting processes. Moreover, based on our former work that verifies SHR greatly simplifies retorting operation by in situ generating heat to replace external heat carrier/provision, this study further demonstrates that SHR also alleviates the environmental effect of organic toxic residues as compared to AR. The present study provides some critical results not only for penetrating the reaction mechanism but also for assessing or controlling the environmental impact of both retorting processes.