Impact of Nickel Doping on Hydrogen Storage in Porous Metal-Organic Frameworks

A supply of clean, carbon neutral and sustainable energy is the most scientific and technical challenge that humanity is facing in the 21st century. Though there is enough fossil fuels available for a few centuries, their use would increase the level of CO2 in the atmosphere. This would lead to global warming and may pose serious threats such as rising of sea level, change in hydrological cycle, etc. Hence there is a need for an alternative source of fuel that is clean and sustainable. Among the many resources considered as an alternative power source, hydrogen is considered one of the most promising candidates. To use hydrogen commercially, appropriate hydrogen storage system is required. Various options to store hydrogen for onboard use include gaseous form in high-pressure tanks, liquid form in cryogenic conditions, solid form in chemical or metal hydrides, or by physisorption of hydrogen on porous materials. One of the emerging porous materials are metal-organic frameworks (MOFs) which provide several advantages over zeolites and carbon materials because the MOFs can be designed to possess variable pore size, dimensions, and metrics. In general, MOFs adsorb hydrogen through weak interactions such as London dispersion and electrostatic potential which lead to low binding enthalpies in the range of 4 to 10 kJ/mol. As a result, cryogenic conditions are required to store sufficient amounts of hydrogen inside MOFs. Up to date several MOFs have been designed and tested for hydrogen storage at variable temperature and pressure levels. The overall results thus far suggest that the use of MOFs for hydrogen storage without chemical and electronic modifications such as doping with electropositive metals or incorporating low density elements such as boron in the MOFs backbone will not yield practical storage media. Such modifications are required to meet gravimetric and volumetric constraints. With these considerations in mind, we have selected a Cr-based MOF (MIL-101; Cr(F,OH)-(H2O)2O[(O2C)-C6H4-(CO2)]3•nH2O (n ≈ 25)) to investigate the impact of nickel inclusion inside the pores of MIL-101 on its performance in hydrogen storage. MIL-101 has a very high Langmuir surface area (5900 m2/g) and two types of mesoporous cavities (2.7 and 3.4 nm) and exhibits exceptional chemical and thermal stabilities. Without any modifications, MIL-101 can store hydrogen reversibly with adsorption enthalpy of 10 kJ/mol which is the highest ever reported among MOFs. At 298 K and 86 bar, MIL-101 can store only 0.36 wt% of hydrogen. Further improvement of hydrogen storage to 5.5 wt% at 40 bar was achieved only at low temperatures (77.3 K). As reported in the literature, hydrogen storage could be improved by doping metals such as Pt. Doping is known to improve hydrogen storage by spillover mechanism and Kubas interaction. Hence we proposed that doping MIL-101 with a relatively light metal possessing large electron density could improve hydrogen adsorption. Preferential Ni doping of the MIL-101’s large cavities which usually do not contribute to hydrogen uptake is believed to improve hydrogen uptake by increasing the potential surface in those cavities. We have used incipient wetness impregnation method to dope MIL-101 with Ni nanoparticles (NPs) and investigated their effect on hydrogen uptake at 77.3 K and 298 K, at 1 bar. In addition, the impact of metal doping on the surface area and pore size distribution of the parent MIL-101 was addressed. Metal content and NPs size was investigated by ICP and TEM, respectively. Furthermore, crystallinity of the resulting doped samples was confirmed by Powder X-ray Diffraction (PXRD) technique. The results of our studies on the successful doping with Ni NPs and their impact on hydrogen adsorption are discussed

Energy efficiency analysis of selected public key cryptoschemes

Public key cryptosystems in both classical and post-quantum settings usually involve a lot of computations. The amount as well as the type of computations involved vary among these cryptosystems. As a result, when the computations are performed on processors or devices, they can lead to a wide range of energy consumption. Since a lot of devices implementing these cryptosystems might have a limited source of power or energy, energy consumption by such schemes is an important aspect to be considered. The Diffie-Hellman key exchange is one of the most commonly used technique in the classical setting of public key cryptographic shceme, and elliptic curve based Diffie-Hellman (ECDH) has been in existence for more than three decades. An elliptic curve based post-quantum version of Diffie-Hellman, called supersingular isogeny based Diffie-Hellman (SIDH) was developed in 2011. For computations involved in ECDH and SIDH, elliptic curve points can be represented in various coordinate systems. In this thesis, a comparative analysis of energy consumption is carried out for the affine and projective coordinate based elliptic curve point addition and doubling used in ECDH and SIDH. We also compare the energy consumption of the entire ECDH and SIDH schemes. SIDH is one of the more than sixty algorithms currently being considered by NIST to develop and standardize quantum-resistant public key cryptographic algorithms. In this thesis, we use a holistic approach to provide a comprehensive report on the energy consumption and power usage of the candidate algorithms executed on a 64-bit processor

Dietary acid load and chronic kidney disease among adults in the United States

Abstract Background Diet can markedly affect acid-base status and it significantly influences chronic kidney disease (CKD) and its progression. The relationship of dietary acid load (DAL) and CKD has not been assessed on a population level. We examined the association of estimated net acid excretion (NAEes) with CKD; and socio-demographic and clinical correlates of NAEes. Methods Among 12,293 U.S. adult participants aged >20 years in the National Health and Nutrition Examination Survey 1999–2004, we assessed dietary acid by estimating NAEes from nutrient intake and body surface area; kidney damage by albuminuria; and kidney dysfunction by eGFR < 60 ml/min/1.73m2 using the MDRD equation. We tested the association of NAEes with participant characteristics using median regression; while for albuminuria, eGFR, and stages of CKD we used logistic regression. Results Median regression results (β per quintile) indicated that adults aged 40–60 years (β [95% CI] = 3.1 [0.3–5.8]), poverty (β [95% CI] = 7.1 [4.01–10.22]), black race (β [95% CI] = 13.8 [10.8–16.8]), and male sex (β [95% CI] = 3.0 [0.7- 5.2]) were significantly associated with an increasing level of NAEes. Higher levels of NAEes compared with lower levels were associated with greater odds of albuminuria (OR [95% CI] = 1.57 [1.20–2.05]). We observed a trend toward greater NAEes being associated with higher risk of low eGFR, which persisted after adjustment for confounders. Conclusion Higher NAEes is associated with albuminuria and low eGFR, and socio-demographic risk factors for CKD are associated with higher levels of NAEes. DAL may be an important target for future interventions in populations at high risk for CKD.http://deepblue.lib.umich.edu/bitstream/2027.42/109474/1/12882_2014_Article_829.pd

Mechanistic Insight into the role of Vitamin D and Zinc in Modulating Immunity Against COVID-19: A View from an Immunological Standpoint

The pathophysiology of coronavirus disease-19 (COVID-19) is characterized by worsened inflammation because of weakened immunity, causing the infiltration of immune cells, followed by necrosis. Consequently, these pathophysiological changes may lead to a life-threatening decline in perfusion due to hyperplasia of the lungs, instigating severe pneumonia, and causing fatalities. Additionally, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection can cause mortality due to viral septic shock, resulting from unrestrained and backfiring immune reactions to the pathogen. Sepsis can cause premature organ failure in COVID-19 patients, as well. Notably, vitamin D and its derivatives and minerals, such as zinc and magnesium, have been reported to improve the immune system against respiratory illnesses. This comprehensive review aims to provide updated mechanistic details of vitamin D and zinc as immunomodulators. Additionally, this review also focuses on their role in respiratory illnesses, while specifically delineating the plausibility of employing them as a preventive and therapeutic agent against current and future pandemics from an immunological perspective. Furthermore, this comprehensive review will attract the attention of health professionals, nutritionists, pharmaceuticals, and scientific communities, as it encourages the use of such micronutrients for therapeutic purposes, as well as promoting their health benefits for a healthy lifestyle and wellbeing

In-Hospital and 1-Year Mortality Trends in a National Cohort of US Veterans with Acute Kidney Injury

BACKGROUND AND OBJECTIVES: AKI, a frequent complication among hospitalized patients, confers excess short- and long-term mortality. We sought to determine trends in in-hospital and 1-year mortality associated with AKI as defined by Kidney Disease Improving Global Outcomes consensus criteria. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: This retrospective cohort study used data from the national Veterans Health Administration on all patients hospitalized from October 1, 2008 to September 31, 2017. AKI was defined by Kidney Disease Improving Global Outcomes serum creatinine criteria. In-hospital and 1-year mortality trends were analyzed in patients with and without AKI using Cox regression with year as a continuous variable. RESULTS: We identified 1,688,457 patients and 2,689,093 hospitalizations across the study period. Among patients with AKI, 6% died in hospital, and 28% died within 1 year. In contrast, in-hospital and 1-year mortality rates were 0.8% and 14%, respectively, among non-AKI hospitalizations. During the study period, there was a slight decline in crude in-hospital AKI-associated mortality (hazard ratio, 0.98 per year; 95% confidence interval, 0.98 to 0.99) that was attenuated after accounting for patient demographics, comorbid conditions, and acute hospitalization characteristics (adjusted hazard ratio, 0.99 per year; 95% confidence interval, 0.99 to 1.00). This stable temporal trend in mortality persisted at 1 year (adjusted hazard ratio, 1.00 per year; 95% confidence interval, 0.99 to 1.00). CONCLUSIONS: AKI associated mortality remains high, as greater than one in four patients with AKI died within 1 year of hospitalization. Over the past decade, there seems to have been no significant progress toward improving in-hospital or long-term AKI survivorship

Markers of mineral metabolism and vascular access complications: The Choices for Healthy Outcomes in Caring for ESRD (CHOICE) study

Introduction: Vascular access dysfunction is a major cause of morbidity in patients with end‐stage renal disease (ESRD) on chronic hemodialysis. The effects of abnormalities in mineral metabolism on vascular access are unclear. In this study, we evaluated the association of mineral metabolites, including 25‐hydroxy vitamin D (25(OH)D) and fibroblast growth factor‐23 (FGF‐23), with vascular access complications.Methods: We included participants from the Choices for Healthy Outcomes in Caring for ESRD (CHOICE) Study who were using an arteriovenous fistula (AVF; n = 103) or arteriovenous graft (AVG; n = 116). Serum levels of 25(OH)D, FGF‐23, parathyroid hormone (PTH), calcium, phosphorus, C‐reactive protein (CRP) and interleukin‐6 (IL‐6) were assessed from stored samples. Participants were followed for up to 1 year or until a vascular access intervention or replacement.Findings: A total of 24 participants using an AVF and 43 participants using an AVG experienced access intervention. Those with 25(OH)D level in the lowest tertile (3750 RU/mL) was associated with greater risk of AVF intervention (aHR = 2.56; 95% CI: 1.06, 6.18). Higher PTH was associated with higher risk of AVF intervention (aHR = 1.64 per SD of log(PTH); 95% CI: 1.02, 2.62). These associations were not observed in participants using an AVG. None of the other analytes were significantly associated with AVF or AVG intervention.Discussion: Low levels of 25(OH)D and high levels of FGF‐23 and PTH are associated with increased risk of AVF intervention. Abnormalities in mineral metabolism are risk factors for vascular access dysfunction and potential therapeutic targets to improve outcomes.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/153726/1/hdi12798_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/153726/2/hdi12798.pd

Exploring reasons for state-level variation in incidence of dialysis-requiring acute kidney injury (AKI-D) in the United States

Background: There is considerable state-level variation in the incidence of dialysis-requiring acute kidney injury (AKI-D). However, little is known about reasons for this geographic variation. Methods: National cross-sectional state-level ecological study based on State Inpatient Databases (SID) and the Behavioral Risk Factor Surveillance System (BRFSS) in 2011. We analyzed 18 states and six chronic health conditions (diabetes mellitus [diabetes], hypertension, chronic kidney disease [CKD], arteriosclerotic heart disease [ASHD], cancer (excluding skin cancer), and chronic obstructive pulmonary disease [COPD]). Associations between each of the chronic health conditions and AKI-D incidence was assessed using Pearson correlation and multiple regression adjusting for mean age, the proportion of males, and the proportion of non-Hispanic whites in each state. Results: The state-level AKI-D incidence ranged from 190 to 1139 per million population. State-level differences in rates of hospitalization with chronic health conditions (mostly \u3c 3-fold difference in range) were larger than the state-level differences in prevalence for each chronic health condition (mostly \u3c 2.5-fold difference in range). A significant correlation was shown between AKI-D incidence and prevalence of diabetes, ASHD, and COPD, as well as between AKI-D incidence and rate of hospitalization with hypertension. In regression models, after adjusting for age, sex, and race, AKI-D incidence was associated with prevalence of and rates of hospitalization with five chronic health conditions - diabetes, hypertension, CKD, ASHD and COPD - and rates of hospitalization with cancer. Conclusions: Results from this ecological analysis suggest that state-level variation in AKI-D incidence may be influenced by state-level variations in prevalence of and rates of hospitalization with several chronic health conditions. For most of the explored chronic conditions, AKI-D correlated stronger with rates of hospitalizations with the health conditions rather than with their prevalences, suggesting that better disease management strategies that prevent hospitalizations may translate into lower incidence of AKI-D