Recovery of cobalt sulfate from spent lithium ion batteries by reductive leaching and solvent extraction with Cyanex 272

Cobalt sulfate was recovered from crushed and screened prismatic type spent lithium ion batteries (LIBs) containing 5-20% Co, 5-7% Li, 5-10% Ni, 15% organic chemicals, and 7% plastics together with Cu, Al, Fe, and Mn. Cobalt was reductively leached from the - 16 mesh fraction in 1 h by stirring with 2 M H2SO4 and 6 vol.% H2O2, at 60 °C and 300 rpm using a solid/liquid ratio of 100 g/L to give a cobalt concentration of 28 g/L, corresponding to a leaching efficiency of > 99%. Metal ion impurities such as copper, iron, and aluminium were precipitated as hydroxides from solution by adjusting pH to 6.5. Cobalt was then selectively extracted from the purified aqueous phase by equilibrating with 50% saponified 0.4 M Cyanex 272 at an equilibrium pH ∼ 6. The McCabe-Thiele plot predicted 99.9% cobalt extraction in a 2 stage counter-current operation with A/O ratio of 1/2. Separation factors for the extraction of Co/Li and Co/Ni at pH 6 were close to 750. The stripping of the loaded organic phase with 2 M H2SO4 produced a solution of 96 g/L Co from which pure pigment grade cobalt sulfate could be recovered by evaporation/recrystallisation. Overall, 92% cobalt could be recovered from the spent lithium ion batteries

Android source code vulnerability detection: a systematic literature review

The use of mobile devices is rising daily in this technological era. A continuous and increasing number of mobile applications are constantly offered on mobile marketplaces to fulfil the needs of smartphone users. Many Android applications do not address the security aspects appropriately. This is often due to a lack of automated mechanisms to identify, test, and fix source code vulnerabilities at the early stages of design and development. Therefore, the need to fix such issues at the initial stages rather than providing updates and patches to the published applications is widely recognized. Researchers have proposed several methods to improve the security of applications by detecting source code vulnerabilities and malicious codes. This Systematic Literature Review (SLR) focuses on Android application analysis and source code vulnerability detection methods and tools by critically evaluating 118 carefully selected technical studies published between 2016 and 2022. It highlights the advantages, disadvantages, applicability of the proposed techniques and potential improvements of those studies. Both Machine Learning (ML) based methods and conventional methods related to vulnerability detection are discussed while focusing more on ML-based methods since many recent studies conducted experiments with ML. Therefore, this paper aims to enable researchers to acquire in-depth knowledge in secure mobile application development while minimizing the vulnerabilities by applying ML methods. Furthermore, researchers can use the discussions and findings of this SLR to identify potential future research and development directions

Uncertainty-Aware Online Merge Planning with Learned Driver Behavior

Safe and reliable autonomy solutions are a critical component of next-generation intelligent transportation systems. Autonomous vehicles in such systems must reason about complex and dynamic driving scenes in real time and anticipate the behavior of nearby drivers. Human driving behavior is highly nuanced and specific to individual traffic participants. For example, drivers might display cooperative or non-cooperative behaviors in the presence of merging vehicles. These behaviors must be estimated and incorporated in the planning process for safe and efficient driving. In this work, we present a framework for estimating the cooperation level of drivers on a freeway and plan merging maneuvers with the drivers' latent behaviors explicitly modeled. The latent parameter estimation problem is solved using a particle filter to approximate the probability distribution over the cooperation level. A partially observable Markov decision process (POMDP) that includes the latent state estimate is solved online to extract a policy for a merging vehicle. We evaluate our method in a high-fidelity automotive simulator against methods that are agnostic to latent states or rely on $\textit{a priori}$ assumptions about actor behavior

Reductive atmospheric acid leaching of lateritic smectite/nontronite ores in H2SO4/Cu(II)/SO2 solutions

Despite the success of reductive atmospheric acid leaching (RAAL) of limonitic nickel laterite ores in recent studies limited attempt has been made to apply this method to smectite/nontronite ores of different mineralogies. A comparative study of four smectite/nontronite ores in this study showed that the use of 700 kg H2SO4/ton dry ore leaches only 74-86% Ni, 37-76% Co, 47-58% Fe and 24-66% Mn at 90 °C from slurries of 20-35% (w/w) pulp density even after 10 h, depending upon the mineralogy. These values increased to 90-97% Ni, 94-97% Co, 92-98% Mn and 72-85% Fe in the presence of Cu(II)/SO2. The first order dependence of initial fraction of iron, aluminium and nickel leached from a typical smectite ore in the first 0.5 h on the initial acid concentration provides evidence for the involvement of hydrogen ions in the surface reaction. Low activation energy of 10 kJ/mol based on the fraction of nickel leached in the first 0.5 h indicates a diffusion controlled reaction. This is supported by the applicability of a shrinking core kinetic model for metal dissolution over the first 2 h, with different apparent rate constants (kap) depending upon the iron oxide content, mineralogy and porosity. A log-log plot of kap for ores with high iron content as a function of acid concentration agrees reasonably well with the correlation already established for the leaching of nickel from limonitic laterite and manganese nodules. Thus, initial fast leaching can be related to the higher porosity and a rate controlling step which involves the diffusion of H+ through a thickening solid layer. The slow leaching at latter stages is a result of low remnant acid, thickening solid layer and changes in mineral composition

Composition and physicochemical properties of oat starches

Starches from two new oat varieties namely AC Stewart (Avena sativa L.) and NO 753-2 (Avena nuda L.) were isolated and some of their characteristics determined. The total amount of starch lipids (TSL) extracted by acid hydrolysis was 1.60% (w/w) in both starches. The free lipid content (extracted by chloroform-methanol (CM) 2:1 v/v at 25°C) was 0.36 and 0.30% (w/w) in NO 753-2 and AC Stewart starches, respectively. The bound lipid content (extracted by hot n-propanol-water 3:1 v/v from the residue left after CM extraction) was 1.27 and 1.37% (w/w) in NO 753-2 and AC Stewart starches, respectively. The total amylose contents were nearly the same (~23%, w/w) in both starches, of which 14.1 (NO 753-2) and 15.3% (AC Stewart) were complexed by native lipids. The starches differed widely in their degree of swelling, gelatinization transition temperatures and enthalpy, susceptibility towards acid and enzyme hydrolysis, gel strength, paste viscosity, thermal stability and retrogradation characteristics. The results suggest that the extent of interaction of starch chains within the amorphous and crystalline regions of the granule was stronger in NO 753-2 than in AC Stewart

Enzyme-assisted synthesis of structured lipids containing long-chain omega-3 and omega-6 polyunsaturated fatty acids

Lipase-catalyzed acidolysis of borage (Borago officinalis L.) and evening primrose (Oenothera biennis L.) oils with long-chain ω3-polyunsaturated fatty acids (LCω3-PUFA), namely docosahexaenoic acid (DHA) and/or eicosapentaenoic acid (EPA), in organic solvents was studied. Six microbial lipases from Candida antarctica, Mucor miehei, Pseudomonas sp., Aspergillus niger, Candida rugosa and Thermomyces lanuginosus were initially used as biocatalysts for the acidolysis reaction. Among the enzymes tested, an immobilized lipase, Novozym-435 from Candida antarctica showed the highest degree of DHA incorporation (25.8-28.7%, after 24 h) in borage oil (BO) and evening primrose oil (EPO). However, the maximum incorporation of EPA (28.7-30.7%, after 24 h) in both oils was achieved with lipase PS-30 from Pseudomonas sp. In another study, incorporation of EPA+DHA into BO and EPO was carried out by first screening of lipases listed above; lipase PS-30 from Pseudomonas sp. was the most efficient enzyme examined (31.7-32.7% EPA+DHA incorporation, after 24 h). -- Effects of variation of reaction parameters, namely enzyme load, temperature, time course, mole ratio of substrates and type of organic solvents were monitored for the most effective enzymes, those from Candida antarctica and Pseudomonas sp., as the biocatalysts of choice. Incorporation of DHA and/or EPA increased significantly (p ≤ 0.05) with increasing the amount of enzyme. As the incubation time progressed, incorporation of these fatty acids was also increased, similar to that observed when the temperature and mole ratio of substrates increased. The highest DHA (37.4-39.7%) or EPA (37.4-39.9%) incorporation occurred at a mole ratio of 1:3 (oil/ DHA or EPA). However, maximum incorporation of EPA+DHA (54-57.5%) occurred at a mole ratio of 1:2:2 (oil/EPA/DHA) and then remained constant between mole ratios of 1:2:2 and 1:3:3. Among solvents examined, n-hexane served best in giving rise to 25.5-27.4% DHA, 25.2-26.8% EPA and 27.8-33.3% EPA+DHA incorporation in the oils. However, solvent-free reactions also gave satisfactory incorporation of 18.1-20.5% DHA, 18.6-20.4% EPA and 23.4-28.8% EPA+DHA in the oils tested. -- Response surface methodology (RSM) was used to obtain a maximum yield of DHA, EPA and EPA+DHA incorporation while using the minimum amount of enzyme possible. Process parameters studied were the amount of enzyme (100-350 units), reaction temperature (20-60°C) and reaction time (6-30 h). All experiments were carried out according to a face-centred cube design. Under optimum conditions (162-165 units of Candida antarctica enzyme: 43-50°C; 25-27 h), incorporation of DHA was 35.6% in BO and 33.5% in EPO. Optimization of acidolysis of oils with EPA, gave rise to a maximum of 35.4 and 33.9% EPA incorporation in BO and EPO, respectively, at 299-309 units of Pseudomonas sp. enzyme, reaction temperature of 40-44°C and reaction time of 25-27 h. Similarly, maximum incorporation of EPA+DHA in BO (35.5%) and EPO (33.6%) was attained at 278-299 units of Pseudomonas sp enzyme, at 42-43°C after 24-26 h. -- In another study, enzymatically modified oils, produced under optimum reaction conditions, were classified using thin-layer chromatography-flame ionization detection (TLC-FID). The results showed that the content of TAG (85.1-95.1%) was much higher than that of the DAG (2.4-11.2%) and MAG (0.3-9.7%) in the structured lipids so produced. Because free fatty acids were removed by NaOH after the acidolysis reaction, they were not detected by TLC-FID. The products were also separated by TLC and the fatty acid compositions of their corresponding isolated bands analyzed by gas chromatography. Results showed that DHA and/or EPA were mainly located in TAG fractions of enzymatically modified oils (33.2-35.4% DHA; 32.5-33.2% EPA and 33.6-35.5% EPA+DHA in DHA, EPA and EPA+DHA-enriched oils, respectively). The TAG fractions also contained appreciable proportions of γ-linolenic acid (GLA) (11.0-17.1 and 7.5-7.6% in DHA, EPA and EPA+DHA-enriched BO and EPO, respectively). -- Stereospecific analysis was carried out to establish positional distribution of fatty acids in the TAG of DHA, EPA and EPA+DHA-enriched oils. In DHA-enriched BO, DHA was randomly distributed over the three positions of TAG while GLA was mainly esterified at the sn-2 and sn-3 positions. In DHA-enriched EPO, however, DHA and GLA were concentrated in the sn-2 position. In EPA-enriched BO, EPA was randomly distributed over the three positions of TAG, similar to that observed for DHA. In EPA-enriched EPO, however, this fatty acid was mainly located at the primary positions (sn-1 and sn-3) of TAG. In both oils, GLA was preferentially esterified at the sn-2 position. In EPA+DHA-enriched BO, EPA and DHA were mainly esterified at the sn-1 and sn-3 positions of TAG while GLA was mainly located at the sn-2 position. In EPA+DHA-enriched EPO, GLA was mainly located at the sn-2 and sn-3 positions; EPA was preferentially esterified at the sn-1 and sn-3 positions, while DHA was found mainly at the sn-3 position. -- The oxidative stability of enzymatically modified oils as well as their unmodified counterparts was evaluated under Schaal oven conditions at 60°C over a 96 h storage period. Conjugated dienes (CD), 2-thiobarbituric acid reactive substances (TBARS) and headspace volatiles were determined. In addition, proton nuclear magnetic resonance (¹H NMR) spectroscopy was used to monitor relative changes in the proton absorption pattern of the fatty acids of oils during storage. Among the oils examined, enzymatically modified products gave rise to higher CD and TBARS as compared to those of their unmodified counterparts. The main volatile compounds identified in enzymatically modified oils were acetaldehyde, propanal, butanal, pentanal, hexanal, heptanal, octanal and nonanal. However, the main volatile compound found in unmodified oils was hexanal. The contents of propanal and hexanal produced by enzymatically modified oils were significantly higher (p ≤ 0.05) than those produced by their unmodified counterparts. These results suggested that the modified oils were more prone to oxidation than their unmodified counterparts. -- The double bond index (DBI) and methylene bridge index (MBI), represent the number of double bonds and bis allylic methylene bridge positions in PUFA, respectively, were calculated. DBI and MBI of enzymatically modified oils were significantly (p ≤ 0.05) higher than those of their unmodified counterparts. During oxidation of oils, DBI and MBI were decreased. Regression analysis was carried out to correlate various parameters of oxidation (CD, TBARS, hexanal and propanal contents) with DBI and MBI of oils; a negative correlation (r = 0.574-0.975; p ≤ 0.1-0.05) existed between these variables. -- Relative changes of aliphatic to olefinic (Rao) and aliphatic to diallylmethylene (Rad) protons ratios, during oil oxidation, were determined by ¹H NMR spectroscopy. An increase in Rao and Rad values was obtained over the entire storage period. A highly significant correlation (r = 0.930-0.992; p ≤ 0.005) existed between the CD values and changes in Rao and Rad during oxidation of all oils. The correlation coefficient between TBARS and changes in Rao and Rad values was in the range of 0.779 -0.983 (p ≤ 0.05). A high correlation (r = 0.948-0.996; p ≤ 0.005) was found between hexanal content and Rao and Rad of oils. Propanal content was also highly correlated (r = 0.950-0.990; p ≤ 0.005) with Rao and Rad. This suggests that ¹H NMR could be used to simultaneously estimate both primary and secondary oxidation changes in native and enzymatically modified oils

Visible light-driven H2 production over highly dispersed Ruthenia on Rutile TiO2 nanorods

The immobilization of miniscule quantities of RuO2 (~0.1%) onto one-dimensional (1D) TiO2 nanorods (NRs) allows H2 evolution from water under visible light irradiation. Rod-like rutile TiO2 structures, exposing preferentially (110) surfaces, are shown to be critical for the deposition of RuO2 to enable photocatalytic activity in the visible region. The superior performance is rationalized on the basis of fundamental experimental studies and theoretical calculations, demonstrating that RuO2(110) grown as 1D nanowires on rutile TiO2(110), which occurs only at extremely low loads of RuO2, leads to the formation of a heterointerface that efficiently adsorbs visible light. The surface defects, band gap narrowing, visible photoresponse, and favorable upward band bending at the heterointerface drastically facilitate the transfer and separation of photogenerated charge carriers.Peer ReviewedPostprint (published version

Long term outcome of acute kidney injury due to leptospirosis? A longitudinal study in Sri Lanka

BACKGROUND: Leptospirosis is an important zoonotic disease of variable severity and is a common cause of acute kidney injury (AKI) in tropics. However the knowledge on long term renal outcome in leptospirosis is scarce. This study aims to assess the long-term renal outcome of AKI caused by leptospirosis. FINDINGS: Hospital records of patients who had developed AKI following leptospirosis (Serologically confirmed) presented to two Teaching Hospitals in Kandy district over 3 years from 2007 were studied. A total of 44 patients were included and they had been followed up at least for one year in out patient clinics with regular assessment including renal status. Renal histology was studied in two patients. The primary outcome measure was normalization of renal function at one year. Of the 44 patients, 31 were in the risk and injury stage (Group 1), and the rest of them were in the failure stage (Group 2) under RIFLE criteria. Of group 2 patients, 11 had abnormal renal functions on discharge. Their mean serum creatinine and GFR values on discharge were 392 mmol/l and 20 ml/min/1.73 m(2). Other two patients had full renal recovery whilst in the hospital. Nine in the group 2 required renal replacement therapy by means of peritoneal dialysis, intermittent haemodialysis or haemofiltration. Seventeen out of the total had persistently abnormal renal functions on discharge. Of them 13 recovered their renal functions to normal. Four patients (9%) who belonged to group 2, had persistently abnormal renal functions after first year compatible with stage 3 chronic kidney disease (CKD). Renal histology of two patients showed tubulointerstitial lymphocyte infiltrate, tubular atrophy and interstitial fibrosis. CONCLUSION: The long term renal outcome of AKI following leptospirosis is satisfactory as only 9% of patients had abnormal renal functions compatible with early stage of CKD. Even among them, advanced CKD or dialysis dependency had not been observed