Domain Adaptation for Inertial Measurement Unit-based Human Activity Recognition: A Survey

Machine learning-based wearable human activity recognition (WHAR) models enable the development of various smart and connected community applications such as sleep pattern monitoring, medication reminders, cognitive health assessment, sports analytics, etc. However, the widespread adoption of these WHAR models is impeded by their degraded performance in the presence of data distribution heterogeneities caused by the sensor placement at different body positions, inherent biases and heterogeneities across devices, and personal and environmental diversities. Various traditional machine learning algorithms and transfer learning techniques have been proposed in the literature to address the underpinning challenges of handling such data heterogeneities. Domain adaptation is one such transfer learning techniques that has gained significant popularity in recent literature. In this paper, we survey the recent progress of domain adaptation techniques in the Inertial Measurement Unit (IMU)-based human activity recognition area, discuss potential future directions

Correlation of structure and ionic-conductivity in phosphate glass using MAS-NMR and impedance spectroscopy: Influence of sodium salt

In the process of diminishing the safety concerns of sodium-ion batteries, the development of glass-based solid electrolyte materials has received adequate interest. Nevertheless, achieving a high ionic-conductivity at room temperature for glass materials remains a challenging task because of the poor correlation between the conductivity and the glass structure. Here, we attempt to understand the effective influence of NaC1 on the structure and ionic-conductivity of the phosphate-based glass network. For this study, xNaCl-(100-x) (31.725 Na2O-12.69 Al2O3-31.725 P2O5-8.46 NaF-5.40 Na2SO4-10 MoO3) glass systems (mol %) were selected, where x = 0, 5, 10, 15, and 20 mol %. To investigate structural changes with the addition of different NaCl concentrations, Al-27, Na-23, P-31 magic angle spinning nuclear magnetic resonance (MAS-NMR), P-31 two-dimensional (2D) phase-adjusted spinning sideband (PASS), and P-31 2D J-resolved NMR techniques and Raman spectroscopic techniques were utilized. Impedance spectroscopy and ac conductivity spectra were used to assess ionic-conductivity and sodium-ion dynamics, respectively. Impedance spectral analysis reveals that the ionic-conductivity of the base glass is increased by 2.4 times (from 1.85 x 10(-7) to 4.44 x 10(-7) S/cm at 373 K) with the addition of 20 mol % of NaCl. Raman spectra confirm the presence of P-O-Mo and the absence of Mo-O-Mo bonds in these glass systems, and P-31 2D J-resolved spectra indicate the absence of P-O-P bonds. Upon increasing the NaCl concentration, significant changes in the shapes of P-31 and Al-27 MAS-NMR spectra were observed, indicating the effective influence of NaCl on the distribution of alumina and phosphorus structural units. Irrespective of the temperature, sodium-ion dynamic studies show that the mean-square displacement decreases with increasing NaCl concentration up to 10 mol % and then increases with a further increase in NaCl concentration. This investigation aids in understanding the sodium-ion dynamics and the structural information of a multicomponent glass system to enhance the room-temperature conductivity

Structure and Conductivity Correlation in NASICON Based Na3Al2P3O12 Glass: Effect of Na2SO4

Identifying the factors influencing the movement of sodium cations (Na+) in glasses accelerates the possible options of glass-based solid electrolyte materials for their applications as a promising electrolyte material in sodium-ion batteries. Nevertheless, due to the poor correlation between the structure and conductivity in glass materials, identifying the factors governing the conductivity still exists as a challenging task. Herein, we have investigated the DC-conductivity variations by correlating the structure and conductivity in sodium superionic conductor (NASICON) based Na3Al2P3O12 (NAP) glass (mol%: 37.5 P2O5-25.0 Al2O3-37.5 Na2O) due to the successive substitution of Na2SO4 for Al2O3. Structural variations have been identified using the Raman and magic-angle spinning nuclear magnetic resonance (MAS-NMR) (for P-31, Na-23, and Al-27 nuclei) and conductivity measurements have been done using the impedance spectroscopy. From the ac-conductivity spectra, the correlations between mean square displacement (MSD) and dc-conductivity and between the Na+ concentration and dc-conductivity have also been evaluated. Raman spectra reveal that the increase in the Na2SO4 concentration increases the number of isolated SO42- sulfate groups that are charge compensated by the Na+ cations in the NAP glass. MAS-NMR spectra reveal that the increase in Na2SO4 concentration increases the concentration of non-bridging oxygens and further neither S-O-P nor S-O-Al bonds are formed. Impedance spectroscopy reveals that, at 373 K, the DC conductivity of the NAP glass increases with increasing the Na2SO4 up to 7.5 mol% and then decreases with the further increase. In the present study, we have shown that the mobility of sodium cations played a significant role in enhancing the ionic-conductivity. Further, we have shown that inter-ionic Coulombic interactions and the structural modification with the formation of SO42- units significantly influence the critical hopping length of the sodium cations and consequently the mobility and the ionic conductivity. The present study clearly indicates that, based on the compositions, glass materials can also be treated as strong-electrolyte materials

Early mobilization in complete spinal cord injury under conservative treatment in a developing country

Background: Spinal cord injury (SCI) management requires extended acute care and life-long chronic care. Aims: The present study was conducted to mobilize complete SCI patients early during conservative treatment and follow them up at the same time weekly for 6 weeks. Materials and Methods: This study was conducted in a time span of 2 years in a tertiary care hospital of Eastern India. All SCI patients admitted in the hospital for the treatment were assessed clinicoradiologically for the level of lesion. Those complete SCI patients who did not recover within 3 weeks of conservative treatment were mobilized with orthosis and efforts were done to recover the activities of daily living (ADL). The effects of early mobilization were monitored and noted at weekly interval with serial radiographs for increasing vertebral collapse and displacement and neurologically up to 6 weeks in the hospital and monthly for a time span of 1 year. Results: Results clearly indicated that guarded mobilization with braces on does not further aggravate the deformity. Bed sores occurred in 8% of cervical cord injury (CCI) and 7% of D-L injury. Respiratory infections occurred in 8% of CCI and 5% of D-L injury. Urinary tract infection affected 12% of CCI and 10% of D-L injury, and the incidences were lower when compared to previous studies, and this may be attributed to early mobilization. Conclusions: Complete SCI patients may be discharged from the hospital within 6 weeks of sustaining an injury with added training for ADL to reduce the social burden in developing countries

Sulfenylnitrene-Mediated Nitrogen-Atom Insertion into Pyrroles, Indoles, and Imidazoles

In this study, we harness the distinct reactivity of sulfenylnitrenes, which insert a single nitrogen atom to transform readily available pyrroles, indoles, and imidazoles into synthetically challenging pyrimidines, quinazolines, and triazines, respectively. Our additive-free method for skeletal editing employs easily accessible, benchtop-stable sulfenylnitrene precursors as a source of a single nitrogen atom. This chemical approach is compatible with free pyrroles, indoles, and imidazoles with diverse functional groups, including oxidation-sensitive functionalities like phenol and thioether. Additionally, this approach facilitates the selective incorporation of a single nitrogen atom into various natural products, amino acids, and pharmaceuticals. Furthermore, we have conducted mechanistic studies and explored regioselectivity outcomes through DFT calculations

Iron-Carbene Initiated O–H Insertion/Aldol Cascade for the Stereoselective Synthesis of Functionalized Tetrahydrofurans

Given its earth abundance, cost-effectiveness, and ecofriendly qualities, iron serves as a promising alternative to precious metals in catalysis. This article presents an iron carbene-initiated cascade approach for synthesizing highly substituted tetrahydrofurans at the gram scale. This cascade reaction utilizes readily accessible β-hydroxyketones and diazo compounds and works with iron catalyst loading as low as 5 mol %. This reaction proceeds through an O–H insertion into diazo-derived iron carbenes, followed by an intramolecular aldol reaction to access functionalized tetrahydrofurans in high yields and diastereoselectivity. The versatile nature of this domino sequence accommodates diverse β-hydroxyketones and diazo compounds, streamlining access to synthetically challenging spiroethers. Furthermore, this cascade process offers a route to enantiopure tetrahydrofurans by utilizing a diazo ester bearing a chiral auxiliary, 8-phenylmenthol. Postmodifications of the tetrahydrofuran product provide access to various analogues, including a medicinally relevant oxetane motif. Density functional theory (DFT) calculations substantiate a stereospecific mechanism wherein the intramolecular aldol reaction proceeds via a fused six- and five-membered iron–oxygen transition-state complex, yielding the contrathermodynamic cis-aldol product

Catalytic Stereoselective 1,2-<i>cis</i>-Furanosylations Enabled by Enynal-Derived Copper Carbenes

1,2-cis-Furanosides are present in various biomedically relevant glycosides, and their stereoselective synthesis remains a significant challenge. In this vein, we have developed a stereoselective approach to 1,2-cis-furanosylations using earth-abundant copper catalysis. This protocol proceeds under mild conditions at room temperature and employs readily accessible benchtop stable enynal-derived furanose donors. This chemistry accommodates a variety of alcohols, including primary, secondary, and tertiary, as well as mannosyl alcohol acceptors, which have been incompatible with most known methods of furanosylation. The resulting 1,2-cis-furanoside products exhibit high yields and anomeric selectivity with both the ribose and arabinose series. Furthermore, the anomeric selectivity is independent of the C2 oxygen-protecting group and the anomeric configuration of the starting donor. Experimental evidence and computational studies support our hypothesis that copper chelation between the C2 oxygen of the furanose donor and an incoming alcohol nucleophile is responsible for the observed 1,2-cis-stereoselectivity

Iron-Carbene Initiated O–H Insertion/Aldol Cascade for the Stereoselective Synthesis of Functionalized Tetrahydrofurans

Given its earth abundance, cost-effectiveness, and ecofriendly qualities, iron serves as a promising alternative to precious metals in catalysis. This article presents an iron carbene-initiated cascade approach for synthesizing highly substituted tetrahydrofurans at the gram scale. This cascade reaction utilizes readily accessible β-hydroxyketones and diazo compounds and works with iron catalyst loading as low as 5 mol %. This reaction proceeds through an O–H insertion into diazo-derived iron carbenes, followed by an intramolecular aldol reaction to access functionalized tetrahydrofurans in high yields and diastereoselectivity. The versatile nature of this domino sequence accommodates diverse β-hydroxyketones and diazo compounds, streamlining access to synthetically challenging spiroethers. Furthermore, this cascade process offers a route to enantiopure tetrahydrofurans by utilizing a diazo ester bearing a chiral auxiliary, 8-phenylmenthol. Postmodifications of the tetrahydrofuran product provide access to various analogues, including a medicinally relevant oxetane motif. Density functional theory (DFT) calculations substantiate a stereospecific mechanism wherein the intramolecular aldol reaction proceeds via a fused six- and five-membered iron–oxygen transition-state complex, yielding the contrathermodynamic cis-aldol product

Role of Sodium-Ion Dynamics and Characteristic Length Scales in Ion Conductivity in Aluminophosphate Glasses Containing Na2SO4

Achieving high ion conductivity in glass-based Na-ion conducting materials for their applications as solid electrolytes in batteries is still challenging owing to the vague knowledge on the factors governing Na-ion dynamics. In the present study, an attempt has been made to identify the factors affecting the sodium-ion dynamics through structure and conductivity property correlation for the 37.5Na(2)O-37.5P(2)O(5)-15Al(2)O(3)-10NaF (FS-0; mol %) glass system with varied concentrations of Na2SO4. P-31, Al-27, and Na-23 MAS NMR (magic-angle spinning nuclear magnetic resonance) and Raman spectroscopy are employed to assess the structural modifications, and impedance spectroscopy is used to measure the variations in ionic conductivity on the addition of Na2SO4 in the FS-0 glass. Raman spectra and MAS NMR analysis indicate that the quantity of P-O-Na bonds and sulfate (SO42-) units surrounded by sodium increase with increasing Na2SO4 concentration. Impedance analysis reveals that the conductivity of FS-0 glass enhances by 1 order with the addition of 6 mol % Na2SO4. We identify from the ac-conductivity spectral analysis that the concentration of charge carriers and the critical hopping length of mobile cations increase with the addition of 6 mol % Na2SO4. Overall, we reveal that the structural modifications, Na-ion concentration, and the shallower potential well that is created for sodium due to its interaction with the nearest neighboring cations affect the Na-ion dynamics. The information obtained from the present study certainly helps to optimize the chemical composition of glasses demonstrating high ionic conductivity