| 11. |
- De Sloovere, Dries, et al.
(författare)
-
Phase Engineering via Aluminum Doping Enhances the Electrochemical Stability of Lithium-Rich Cobalt-Free Layered Oxides for Lithium-Ion Batteries
- 2024
-
Ingår i: Small. - 1613-6810 .- 1613-6829.
-
Tidskriftsartikel (refereegranskat)abstract
- Lithium-rich, cobalt-free oxides are promising potential positive electrode materials for lithium-ion batteries because of their high energy density, lower cost, and reduced environmental and ethical concerns. However, their commercial breakthrough is hindered because of their subpar electrochemical stability. This work studies the effect of aluminum doping on Li1.26Ni0.15Mn0.61O2 as a lithium-rich, cobalt-free layered oxide. Al doping suppresses voltage fade and improves the capacity retention from 46% for Li1.26Ni0.15Mn0.61O2 to 67% for Li1.26Ni0.15Mn0.56Al0.05O2 after 250 cycles at 0.2 C. The undoped material has a monoclinic Li2MnO3-type structure with spinel on the particle edges. In contrast, Al-doped materials (Li1.26Ni0.15Mn0.61-xAlxO2) consist of a more stable rhombohedral phase at the particle edges, with a monoclinic phase core. For this core-shell structure, the formation of Mn3+ is suppressed along with the material's decomposition to a disordered spinel, and the amount of the rhombohedral phase content increases during galvanostatic cycling. Whereas previous studies generally provided qualitative insight into the degradation mechanisms during electrochemical cycling, this work provides quantitative information on the stabilizing effect of the rhombohedral shell in the doped sample. As such, this study provides fundamental insight into the mechanisms through which Al doping increases the electrochemical stability of lithium-rich cobalt-free layered oxides.
|
|
| 12. |
|
|
| 13. |
- Graham, Lesley A, et al.
(författare)
-
Validation of Uromodulin as a Candidate Gene for Human Essential Hypertension
- 2014
-
Ingår i: Hypertension. - 0194-911X .- 1524-4563. ; 63:3, s. 551-558
-
Tidskriftsartikel (refereegranskat)abstract
- A recent genome-wide association study identified a locus on chromosome 16 in the promoter region of the uromodulin (UMOD) gene that is associated with hypertension. Here, we examined the hypertension signal with functional studies in Umod knockout (KO) mice. Systolic blood pressure was significantly lower in KO versus wild-type (WT) mice under basal conditions (KO: 116.6±0.3 mm Hg versus WT: 136.2±0.4 mm Hg; P<0.0001). Administration of 2% NaCl did not alter systolic blood pressure in KO mice, whereas it increased in WT mice by ≈33%, P<0.001. The average 24-hour urinary sodium excretion in the KO was greater than that of WT mice (P<0.001). Chronic renal function curves demonstrate a leftward shift in KO mice, suggesting that the relationship between UMOD and blood pressure is affected by sodium. Creatinine clearance was increased during salt loading with 2% NaCl in the KO mice, leading to augmented filtered Na(+) excretion and further Na(+) loss. The difference in sodium uptake that exists between WT and KO strains was explored at the molecular level. Urinary tumor necrosis factor-α levels were significantly higher in KO mice compared with WT mice (P<0.0001). Stimulation of primary thick ascending limb of the loop of Henle cells with exogenous tumor necrosis factor-α caused a reduction in NKCC2A expression (P<0.001) with a concurrent rise in the levels of UMOD mRNA (P<0.001). Collectively, we demonstrate that UMOD regulates sodium uptake in the thick ascending limb of the loop of Henle by modulating the effect of tumor necrosis factor-α on NKCC2A expression, making UMOD an important determinant of blood pressure control.
|
|
| 14. |
- Kanhed, Satish, et al.
(författare)
-
Microporous Hydroxyapatite Ceramic Composites as Tissue Engineering Scaffolds : An Experimental and Computational Study
- 2018
-
Ingår i: Advanced Engineering Materials. - : Wiley. - 1438-1656 .- 1527-2648. ; 20:7
-
Tidskriftsartikel (refereegranskat)abstract
- Bone‐tissue engineering mandates the development of multi‐functional bioactive porous hydroxyapatite (HAp) scaffolds. Herein, microwave sintered HAp/ZnO and HAp/Ag composite scaffolds with ≈5–19% porosity are developed using 0–30 vol% graphite as a porogen. The mechanical properties of the porous scaffold are analyzed in detail, revealing that even being more porous, the reinforcement of ZnO (9% porosity, hardness of 2.8 GPa, and toughness of 3.5 MPa.m1/2) has shown to have better hardness and fracture toughness when compared to Ag (5% porosity, hardness of 1.6 GPa, and toughness of 2.6 MPa.m1/2). The flexural strength obtained experimentally are complemented with a finite‐element technique that adopts microstructural features in visualizing the effect of porosity on stress distribution. The antibacterial efficacy and cytocompatibility of these composites are validated by increased metabolic activity and conspicuous cell‐matrix interactions. The anticipation of the results reveal that HAp/ZnO (9% porosity) and HAp/Ag (5% porosity) composites can be used as a potential multi‐functional bone implant scaffolds.
|
|
| 15. |
- Kawalkar, Rajat, et al.
(författare)
-
A review for advancements in standardization for additive manufacturing
- 2022
-
Ingår i: Materials today. - : Elsevier. - 2214-7853. ; , s. 1983-1990
-
Konferensbidrag (refereegranskat)abstract
- The need for standardization is important for all sectors starting from industrial manufacturers to delivering it to the consumers. The acceptance of AM in all aspects of manufacturing is always subjected to a lack of additive manufacturing standards. This issue is always being addressed by an eminent group of researchers, and scientists and organizations over the last three decades for developing the desired qualified standards in additive manufacturing. However, ASTM) and ISO along with different research groups have been working with high integrity to resolve this aspect to a greater extent across all sectors. The current research signifies the adoption of standards between ASTM and ISO for enforcing it globally by law with the inculcation of common AM standards. This work emphasizes recent development carried by such organizations and projects, depending on pathways laid by the conductance of several workshops with a focus on developing new standards in this field.
|
|
| 16. |
- Kawalkar, Rajat, et al.
(författare)
-
Wire arc additive manufacturing : A brief review on advancements in addressing industrial challenges incurred with processing metallic alloys
- 2022
-
Ingår i: Materials today. - : Elsevier. - 2214-7853. ; , s. 1971-1978
-
Konferensbidrag (refereegranskat)abstract
- Whenever there is a need for manufacturing products with higher deposition rates (usually more than 10 kg per hour) with different alloys of primary metal materials such as titanium, nickel, aluminum, steel and other superalloys, wire arc additive manufacturing is often considered the best AM (additive manufacturing) technology from the state of art technologies around practice. This practice usually incorporates usage of wire as a feedstock material with standard tools used for arc welding. The perks associated with higher deposition rates of material, low wastage and higher equipment costs combined with structure intactness makes it an irresistible process to override traditional billeting and forging methods ranging from low to medium complex manufacturing products. Large applications can be seen in existence with the help of this technology such as manufacturing assembly line for automobile sectors, wing ribs in aerospace industry, wind tunnels in hydraulic sector. This paper discusses the usual complexities faced with managing residual stress in manufactured product, also with prime focus on improving mechanical properties as compared to traditional methods while eliminating defects such as porosity and distortions are widely discussed in detail. Finally, the prospects of post machining operations carried over product such as non-destructive testing, in-situ process and monitoring are assessed.
|
|
| 17. |
- Kumar, T. K. Satish, et al.
(författare)
-
On the Traveling Salesman Problem with Simple Temporal Constraints
- 2013
-
Ingår i: Proceedings of the 10th Symposium on Abstraction, Reformulation, and Approximation (SARA). - : AAAI Press. - 9781577356301
-
Konferensbidrag (refereegranskat)abstract
- Many real-world applications require the successful combination of spatial and temporal reasoning. In this paper, we study the general framework of the Traveling Salesman Problem with Simple Temporal Constraints. Representationally, this framework subsumes the Traveling Salesman Problem, Simple Temporal Problems, as well as many of the frameworks described in the literature. We analyze the theoretical properties of the combined problem providing strong inapproximability results for the general problem, and positive results for some special cases.
|
|
| 18. |
- Kumar, T. K. Satish, et al.
(författare)
-
Simple Temporal Problems with Taboo Regions
- 2013
-
Ingår i: Proceedings of the Twenty-Seventh AAAI Conference on Artificial Intelligence (AAAI). - : AAAI Press.
-
Konferensbidrag (refereegranskat)abstract
- In this paper, we define and study the general framework of Simple Temporal Problems with Taboo regions (STPTs) and show how these problems capture metric temporal reasoning aspects which are common to many real-world applications. STPTs encode simple temporal constraints between events and user-defined taboo regions on the timeline, during which no event is allowed to take place. We discuss two different variants of STPTs. The first one deals with (instantaneous) events, while the second one allows for (durative) processes. We also provide polynomial-time algorithms for solving them. If all events or processes cannot be scheduled outside of the taboo regions, one needs to define and reason about "soft" STPTs. We show that even "soft" STPTs can be solved in polynomial time, using reductions to max-flow problems. The resulting algorithms allow for incremental computations, which is important for the successful application of our approach in real-time domains.
|
|
| 19. |
- Kumar, Varun, et al.
(författare)
-
Highly time-resolved chemical speciation and source apportionment of organic aerosol components in Delhi, India, using extractive electrospray ionization mass spectrometry
- 2022
-
Ingår i: Atmospheric Chemistry And Physics. - : Copernicus GmbH. - 1680-7316 .- 1680-7324. ; 22:11, s. 7739-7761
-
Tidskriftsartikel (refereegranskat)abstract
- In recent years, the Indian capital city of Delhi has been impacted by very high levels of air pollution, especially during winter. Comprehensive knowledge of the composition and sources of the organic aerosol (OA), which constitutes a substantial fraction of total particulate mass (PM) in Delhi, is central to formulating effective public health policies. Previous source apportionment studies in Delhi identified key sources of primary OA (POA) and showed that secondary OA (SOA) played a major role but were unable to resolve specific SOA sources. We address the latter through the first field deployment of an extractive electrospray ionization time-of-flight mass spectrometer (EESI-TOF) in Delhi, together with a high-resolution aerosol mass spectrometer (AMS). Measurements were conducted during the winter of 2018/19, and positive matrix factorization (PMF) was used separately on AMS and EESI-TOF datasets to apportion the sources of OA. AMS PMF analysis yielded three primary and two secondary factors which were attributed to hydrocarbon-like OA (HOA), biomass burning OA (BBOA-1 and BBOA-2), more oxidized oxygenated OA (MO-OOA), and less oxidized oxygenated OA (LO-OOA). On average, 40 % of the total OA mass was apportioned to the secondary factors. The SOA contribution to total OA mass varied greatly between the daytime (76.8 %, 10:00–16:00 local time (LT)) and nighttime (31.0 %, 21:00–04:00 LT). The higher chemical resolution of EESI-TOF data allowed identification of individual SOA sources. The EESI-TOF PMF analysis in total yielded six factors, two of which were primary factors (primary biomass burning and cooking-related OA). The remaining four factors were predominantly of secondary origin: aromatic SOA, biogenic SOA, aged biomass burning SOA, and mixed urban SOA. Due to the uncertainties in the EESI-TOF ion sensitivities, mass concentrations of EESI-TOF SOA-dominated factors were related to the total AMS SOA (i.e. MO-OOA + LO-OOA) by multiple linear regression (MLR). Aromatic SOA was the major SOA component during the daytime, with a 55.2 % contribution to total SOA mass (42.4 % contribution to total OA). Its contribution to total SOA, however, decreased to 25.4 % (7.9 % of total OA) during the nighttime. This factor was attributed to the oxidation of light aromatic compounds emitted mostly from traffic. Biogenic SOA accounted for 18.4 % of total SOA mass (14.2 % of total OA) during the daytime and 36.1 % of total SOA mass (11.2 % of total OA) during the nighttime. Aged biomass burning and mixed urban SOA accounted for 15.2 % and 11.0 % of total SOA mass (11.7 % and 8.5 % of total OA mass), respectively, during the daytime and 15.4 % and 22.9 % of total SOA mass (4.8 % and 7.1 % of total OA mass), respectively, during the nighttime. A simple dilution–partitioning model was applied on all EESI-TOF factors to estimate the fraction of observed daytime concentrations resulting from local photochemical production (SOA) or emissions (POA). Aromatic SOA, aged biomass burning, and mixed urban SOA were all found to be dominated by local photochemical production, likely from the oxidation of locally emitted volatile organic compounds (VOCs). In contrast, biogenic SOA was related to the oxidation of diffuse regional emissions of isoprene and monoterpenes. The findings of this study show that in Delhi, the nighttime high concentrations are caused by POA emissions led by traffic and biomass burning and the daytime OA is dominated by SOA, with aromatic SOA accounting for the largest fraction. Because aromatic SOA is possibly more toxic than biogenic SOA and primary OA, its dominance during the daytime suggests an increased OA toxicity and health-related consequences for the general public.
|
|
| 20. |
- Shanmugam, Vigneshwaran, et al.
(författare)
-
Introduction to lightweight materials
- 2022. - 1
-
Ingår i: Materials for Lightweight Constructions. - Boca Raton : CRC Press. - 9781003252108 ; , s. 1-15
-
Bokkapitel (övrigt vetenskapligt/konstnärligt)
|
|
