Alloys based on NiAl for high temperature applications

The NiAl alloys for potential high temperature applications were studied. Alloys were prepared by powder metallurgy techniques. Flow stress values at slow strain rates and high temperatures were measured. Some ternary alloying additions (Hf, Ta and Nb) were identified. The mechanism of strengthening in alloys containing these additions appears to be a form of particle dislocation interaction. The effects of grain size and stoichiometry in binary alloys are also presented

Predictors of impending acute chest syndrome in patients with sickle cell anaemia.

Acute chest syndrome (ACS) is a major complication of sickle cell anaemia (SCA) and a leading cause for hospital admissions and death. We aimed to study the spectrum of clinical and laboratory features of ACS and to assess the predisposing factors and predictors of severity. A retrospective case-control cohort was studied by retrieving patient information from electronic medical records after ethical approval. One hundred adolescents and adults with SCA and hospital admissions for ACS were identified through the discharge summaries, along with 20 additional patients presenting with VOC, but without ACS (controls). Among the patients with ACS, fever (\u3e38.5 °C), reduced oxygen saturation (\u3c95) and asplenia significantly differed when compared to those of controls (p \u3c 0.05, chi-squared test). The degree of severity was reflected in the use of non-invasive ventilation (NIV), simple and exchange transfusions, and the presence of bilateral pleural effusions and multi-lobar atelectasis/consolidation, which were significantly higher in the cases with ACS than in the controls. Lower haemoglobin (Hb) and high WBC counts were also significantly different between the two groups (p \u3c 0.05, Student’s t test). Using logistic regression, our study further demonstrated that asplenia, fever, and reduced O2 saturation, along with low Hb and leukocytosis, were important predictors for the development of ACS

A review of issues and challenges

Determining the ages of young planetary surfaces relies on using populations of small, often sub-km diameter impact craters due to the higher frequency at which they form. Smaller craters however can be less reliable for estimating ages as their size-frequency distribution is more susceptible to alteration with debate as to whether they should be used at all. With the current plethora of meter-scale resolution images acquired of the lunar and Martian surfaces, small craters have been widely used to derive model ages to establish the temporal relation of recent geologic events. In this review paper, we discuss the many factors that make smaller craters particularly challenging to use and should be taken into consideration when crater counts are confined to small crater diameters. Establishing confidence in a model age ultimately requires an understanding of the geologic context of the surface being dated as reliability can vary considerably and limitations of the dating technique should be considered in applying ages to any geologic interpretation

The role of C. elegans NHR-49 in regulating global lipid homeostasis

Mammalian nuclear receptors broadly influence metabolic fitness and serve as popular targets for developing drugs to treat cardiovascular disease, obesity and diabetes. However, the molecular mechanisms and regulatory pathways that govern lipid metabolism, one of the primary energy sources in physiological settings, remain poorly understood. I chose the model organism C elegans to elucidate how nuclear receptors and their regulatory partners maintain global metabolic homeostasis and coordinate multiple signals from different tissues under different contexts to modulate the appropriate transcriptional programs. I set out to explore the impact of the C elegans lipid sensing nuclear receptor NHR-49 on global animal metabolism and physiology. Genome-wide gene expression studies revealed that NHR-49 broadly regulates target genes that fall into several physiological categories including energy balance, lipid binding, lipid degradation, sphingolipid breakdown, lipid remodeling, yolk synthesis/transfer and mitochondrial biogenesis. Worms lacking nhr-49 function display a host of phenotypes that very closely mirror its gene expression profile. I identified NHR-49 co-factors that influence NHR-49 gene regulation and demonstrated that each receptor accounts for a specific subset of NHR-49 targets. Furthermore, I used deletion mutants of these individual co-factors to delineate their specific contribution to distinct phenotypes of nhr-49-/- animals. This work has identified genes and pathways that were previously not known to be regulated by NHR-49. In addition, ultrastructural analysis revealed that NHR-49 and its partner proteins participate in the orchestration of the influx and efflux of global energy stores into and from different tissues. And, finally, I discovered a previously uncharacterized role for NHR-49 in influencing mitochondrial physiology. Taken together, my findings in C. elegans not only provide novel insights into how nuclear receptor transcriptional networks coordinate to regulate global energy metabolism but also reveal the breadth of their influence on different aspects of animal physiology

Grass and herb photosynthesis and productivity in a resource-limited Eucalyptus woodland under elevated atmospheric CO2

It has been suggested that plant species from the warmer ecosystems will show different and potentially larger photosynthesis and productivity responses to elevated CO2 (eCO2, ambient + 150 ppm) compared to those from the cold temperate ecosystems, on the basis of higher average annual temperature and greater water deficits in the former ecosystems. Based on these expectations, it has further been predicted that the warm water-limited ecosystems may have a greater potential to sequester the extra C that has been assimilated under eCO2. However, empirical evidences testing these expectations are scarce. The overall aim of this thesis was to investigate the effects of eCO2 on photosynthesis and productivity responses of the evergreen C3 herbaceous species from the understory of a periodically water-limited warm-temperate Eucalyptus woodland. In a three-year field study conducted at the Eucalyptus free-air CO2 enrichment experiment (EucFACE), I investigated how eCO2-induced enhancement of photosynthetic rates (Anet) in herbaceous species varied with seasonal water availability. During the second and third year of CO2 fertilisation at EucFACE, I measured the seasonal photosynthetic acclimation responses to eCO2 in two dominant species- a C3 forb and a C3 grass, and measured responses of peak above-ground biomass to eCO2 for total forbs and grasses. In a glasshouse experiment, I tested whether the species or functional groups growing under similar water inputs and nutrient availability differed in their photosynthetic or biomass allocation and growth responses to eCO2 for two C3 forbs and two C3 grasses. also evidence of photosynthetic acclimation under eCO2 in the dominant C3 herbaceous species, especially during the peak growing season of spring. Also, there was no proportional stimulation of peak above-ground biomass in the understory grasses and forbs, which may have been a result of lack of a ‘water-savings effect’ of eCO2 and/or higher soil nutrient limitation. C3 grasses and C3 forbs differed in their photosynthetic and biomass allocation responses to eCO2. Differences in leaf N content, N allocation and changes in above-ground biomass allocation likely affected the CO2 responsiveness in these functional groups. In particular, there was an ability to maintain greater leaf area index, N allocation to photosynthesis and avoid down-regulation under eCO2 by the grasses but not by the forbs. Findings from the current study suggest that interactions between seasonal water-availability eCO2 will be critical in determining relative Anet enhancement response in herbaceous species from a water-limited ecosystem. However, the enhancement response may not be mediated via a ‘water-savings effect’ of eCO2, which contrasts with the earlier findings from cold temperate ecosystems. Furthermore, evidence of photosynthetic capacity down-regulation in the dominant species and lack of relative increase in biomass under eCO2, suggest a limited capacity of the understory herbaceous species from a grassy woodland to respond to eCO2 and ultimately act as an aboveground C sink in future

Online Mode: A challenge for students and teachers

The COVID pandemic situation led to a new phase of learning throughout the world – the online learning mode (Gamage et al., 2020). The use of online platforms (e.g. Zoom, Microsoft Teams, Google meet) became mandatory for all schools and colleges. These platforms enabled teachers to deliver the academic content to the students to meet the curriculum requirements. The methods of conducting the assessments also were revamped (Montenegro-Rueda et al., 2021). Though the effectiveness of this content transfer is questioned at many academic forums (Dung, 2020), it certainly opened an alternative to maintain a certain minimum amount of exchange of information between a teacher and a student. In India, the lecture sessions were being conducted online, albeit with reduced duration. The contents of the curricula were being reduced. Though these changes ensured teacher-student interaction to some extent, they brought about significant impact on the teaching-learning process. One of the authors, who was a teacher at a reputed IB curriculum school during the pandemic situation, observed some of the challenges faced by the student and teacher communities. One of these challenges was the lack of physical interaction between teacher and student communities. Students were confined to computer screens and fixed environment for interactions. Lack of physical interaction led to some decline in their attention span during the classes. It also reflected in the form of behavioral changes in some students. Teachers adopted different methods and resources to gain their attention and deliver the academic content as efficiently as possible. Alternatives had to be used to compensate for the unavailability of laboratories. There were also some positive results of the online mode. The safety of student-teacher community was one of the main outcomes. Significant attention was given to maintain the health and fitness of students by the school as well as by the Government. The authors, therefore, felt the need to probe the outcomes of the online mode of learning based on the observations mentioned earlier. The sample chosen for the study was from grade XII (N = 38) of the IB curriculum. Students responded to a google form questionnaire. Interviews were conducted with some of the students (N = 15) in an online format. We also discuss some of the responses where students realized the importance of the offline mode of learning, and they expressed a sense of respect and belongingness towards their academic institutions. REFERENCES Dung, D. T. H. (2020). The advantages and disadvantages of virtual learning. IOSR Journal of Research & Method in Education, 10(3), 45-48. Gamage, K. A., Wijesuriya, D. I., Ekanayake, S. Y., Rennie, A. E., Lambert, C. G., & Gunawardhana, N. (2020). Online delivery of teaching and laboratory practices: Continuity of university programmes during COVID-19 pandemic. Education Sciences, 10(10), 291. Montenegro-Rueda, M., Luque-de la Rosa, A., Sarasola Sánchez-Serrano, J. L., & Fernández-Cerero, J. (2021). Assessment in higher education during the COVID-19 pandemic: A systematic review. Sustainability, 13(19), 10509

Dust Devil Tracks

Dust devils that leave dark- or light-toned tracks are common on Mars and they can also be found on the Earth’s surface. Dust devil tracks (hereinafter DDTs) are ephemeral surface features with mostly sub-annual lifetimes. Regarding their size, DDT widths can range between ∼1 m and ∼1 km, depending on the diameter of dust devil that created the track, and DDT lengths range from a few tens of meters to several kilometers, limited by the duration and horizontal ground speed of dust devils. DDTs can be classified into three main types based on their morphology and albedo in contrast to their surroundings; all are found on both planets: (a) dark continuous DDTs, (b) dark cycloidal DDTs, and (c) bright DDTs. Dark continuous DDTs are the most common type on Mars. They are characterized by their relatively homogenous and continuous low albedo surface tracks. Based on terrestrial and martian in situ studies, these DDTs most likely form when surficial dust layers are removed to expose larger-grained substrate material (coarse sands of ≥500 μm in diameter). The exposure of larger-grained materials changes the photometric properties of the surface; hence leading to lower albedo tracks because grain size is photometrically inversely proportional to the surface reflectance. However, although not observed so far, compositional differences (i.e., color differences) might also lead to albedo contrasts when dust is removed to expose substrate materials with mineralogical differences. For dark continuous DDTs, albedo drop measurements are around 2.5 % in the wavelength range of 550–850 nm on Mars and around 0.5 % in the wavelength range from 300–1100 nm on Earth. The removal of an equivalent layer thickness around 1 μm is sufficient for the formation of visible dark continuous DDTs on Mars and Earth. The next type of DDTs, dark cycloidal DDTs, are characterized by their low albedo pattern of overlapping scallops. Terrestrial in situ studies imply that they are formed when sand-sized material that is eroded from the outer vortex area of a dust devil is redeposited in annular patterns in the central vortex region. This type of DDT can also be found in on Mars in orbital image data, and although in situ studies are lacking, terrestrial analog studies, laboratory work, and numerical modeling suggest they have the same formation mechanism as those on Earth. Finally, bright DDTs are characterized by their continuous track pattern and high albedo compared to their undisturbed surroundings. They are found on both planets, but to date they have only been analyzed in situ on Earth. Here, the destruction of aggregates of dust, silt and sand by dust devils leads to smooth surfaces in contrast to the undisturbed rough surfaces surrounding the track. The resulting change in photometric properties occurs because the smoother surfaces have a higher reflectance compared to the surrounding rough surface, leading to bright DDTs. On Mars, the destruction of surficial dust-aggregates may also lead to bright DDTs. However, higher reflective surfaces may be produced by other formation mechanisms, such as dust compaction by passing dust devils, as this may also cause changes in photometric properties. On Mars, DDTs in general are found at all elevations and on a global scale, except on the permanent polar caps. DDT maximum areal densities occur during spring and summer in both hemispheres produced by an increase in dust devil activity caused by maximum insolation. Regionally, dust devil densities vary spatially likely controlled by changes in dust cover thicknesses and substrate materials. This variability makes it difficult to infer dust devil activity from DDT frequencies. Furthermore, only a fraction of dust devils leave tracks. However, DDTs can be used as proxies for dust devil lifetimes and wind directions and speeds, and they can also be used to predict lander or rover solar panel clearing events. Overall, the high DDT frequency in many areas on Mars leads to drastic albedo changes that affect large-scale weather patterns

Field Measurements of Terrestrial and Martian Dust Devils

Surface-based measurements of terrestrial and martian dust devils/convective vortices provided from mobile and stationary platforms are discussed. Imaging of terrestrial dust devils has quantified their rotational and vertical wind speeds, translation speeds, dimensions, dust load, and frequency of occurrence. Imaging of martian dust devils has provided translation speeds and constraints on dimensions, but only limited constraints on vertical motion within a vortex. The longer mission durations on Mars afforded by long operating robotic landers and rovers have provided statistical quantification of vortex occurrence (time-of-sol, and recently seasonal) that has until recently not been a primary outcome of more temporally limited terrestrial dust devil measurement campaigns. Terrestrial measurement campaigns have included a more extensive range of measured vortex parameters (pressure, wind, morphology, etc.) than have martian opportunities, with electric field and direct measure of dust abundance not yet obtained on Mars. No martian robotic mission has yet provided contemporaneous high frequency wind and pressure measurements. Comparison of measured terrestrial and martian dust devil characteristics suggests that martian dust devils are larger and possess faster maximum rotational wind speeds, that the absolute magnitude of the pressure deficit within a terrestrial dust devil is an order of magnitude greater than a martian dust devil, and that the time-of-day variation in vortex frequency is similar. Recent terrestrial investigations have demonstrated the presence of diagnostic dust devil signals within seismic and infrasound measurements; an upcoming Mars robotic mission will obtain similar measurement types

DEVELOPMENT AND VALIDATION OF ANALYTICAL METHOD FOR ISOSULFAN BLUE BY LIQUID CHROMATOGRAPHY

Objective: To develop and validate new, simple and rapid analytical method for determination of related impurities in isosulfan blue drug substances by the liquid chromatographic method as per ICH guidelines.Methods: The chromatographic separation obtained between drug substance i.e. isosulfan blue and its related impurities (Impurity-A, Impurity-B and Impurity-C) on C18 (100 x 2.00 mm) 1.9µ UPLC column using a mobile phase system containing 0.1 % perchloric acid in water (Mobile phase A) and 0.1 % perchloric acid in mixture of 30 volumes of water and 70 volumes of acetonitrile (Mobile Phase B) with gradient program; detector wavelength 220 nm and column temperature 30 °C. The developed method was extensively validated according to ICH guidelines.Results: Good linearity was observed for isosulfan blue, impurity-A, impurity-B and impurity-C, linearity was calculated from loq Level To 150%with respect to specification level. The correlation coefficient R = 0.999 was proved and showed that the method is robust. The limit of detection of isosulfan blue, impurity-A, impurity-B and impurity-C were found to be 0.010%, 0.015%, 0.030% and 0.0075 % respectively and limit of quantitation of isosulfan blue, impurity-A, impurity-B and impurity-C were found to be 0.030%, 0.030%, 0.045% and 0.015% respectively for 2ml injection volume. The percentage recovery of isosulfan blue and its related impurities were ranged from 94.0 to 108.0 in bulk drug samples. Isosulfan blue sample solution and mobile phase were found to be stable for at least 72 h. The proposed method was found to be suitable and accurate for the quantitative determination of impurity-A, impurity-B, impurity-C and other unknown impurities in isosulfan blue drug substances.Conclusion: A new, simple and rapid method has been developed and validated for separation and determination of impurity-A, impurity-B, impurity-C and unknown impurities of isosulfan blue by the reverse-phase liquid chromatographic method. Analytical method was developed and validated as per ICH guidelines.The developed method can be used for the quantitative determination of impurity A, impurity B, impurity C and unknown impurities in isosulfan blue drug substances in pharmaceutical industry

ENANTIOMERIC SEPARATION OF ETODOLAC IN A BULK DRUG SUBSTANCE BY REVERSE-PHASE CHIRAL LIQUID CHROMATOGRAPHY METHOD

Objective: To develop novel, simple and rapid enantiomeric separation of Etodolac by reverse-phase high-performance liquid chromatographic method as per ICH guidelines.Methods: The R-isomer and S-isomer were baseline resolved on a CHIRAL-AGP, (100 x 4.0 mm i. d, 5 mm) column using a mobile phase system containing 0.1 M sodium dihydrogen phosphate dihydrate pH 4.0 buffer: Isopropanol (85:15 v/v.) at detector wavelength 225 nm and column temperature 25 °C. The chromatographic resolutions between R-isomer and S-isomer were found three. The developed method was extensively validated according to ICH guidelines.Results: Good linearity was observed for R-isomer over the concentration range of 300–3000 ng/ml, with the linear regression (Correlation coefficient R = 0.999) and proved to be robust. The limit of detection and limit of quantification of R-isomer was found to be 300 and 900 ng/ml, respectively for 10 ml injection volume. The percentage recovery of R-isomer was ranged from 98.0 to 102.0 in bulk drug samples of Etodolac. Etodolac sample solution and mobile phase were found to be stable for at least 48 hours. The proposed method was found to be suitable and accurate for the quantitative determination of R-isomer in bulk drugs.Conclusion: A novel, simple and rapid enantiomeric separation of Etodolac by reverse-phase high-performance liquid chromatographic method was developed and validated as per ICH guidelines. The developed method can be used for the quantitative determination R-isomer in bulk drug materials in pharmaceutical industry.Â