Hydrothermal carbonisation of microalgae: Feedstock characterisation, model compound decomposition, and assessment of product recovery methods

Australia presents a reasonable contribution to the World’s greenhouse gas emissions because of its heavy reliance on fossil fuels for energy production. Coal is the primary founder of energy in Australia with the secondary sourcing from oil, gas, solar, wind, biomass and hydro. Bioenergy currently offers only 1 % of the total energy produced in Australia with anticipated uplift to 8 % by 2030 that demands active research on biofuel resources and production processes. Australia lavishes with land, sunlight, and brackish water, necessary for the growth of algal biomass, the unique composition (carbohydrates, lipids, proteins, nucleic acid and moisture) of which makes it an excellent feedstock for hydrothermal processing. Hydrothermal treatment of algal biomass for the production of biofuels and value-added products is an attractive route towards increasing the bio-energy contribution in Australia to meet the challenges of growing greenhouse gas emissions. Hydrothermal treatment of algal biomass at high temperatures (280 – 700 °C) to produce energy-dense liquid and gaseous fuels are extensively researched for the last three decades with the exceptional attributes achieved in the field. However, the low temperature (180 – 260 °C) hydrothermal carbonisation (HTC) of algal biomass, which essentially serves as an intermediate stage of intense hydrothermal processing, has received less attention. Hydrothermal carbonisation produces hydrochar as a primary product along with biocrude and aqueous phase as co-products, all of which possess exceptional traits to be employed directly or indirectly as biofuels and/or as advanced carbon materials. Despite the rationale research on hydrothermal carbonisation of algal biomass, there are still significant research gaps in assessing the feasibility of hydrothermal carbonisation process for microalgae in the context of an Algal Biorefinery, including (i) the lack of standardised conditions for the characterisation (e.g., proximate analysis) of algal biomass; (ii) detailed mechanisms for the evolution of nitrogen-containing species from thermal decomposition of algal biomass; (iii) the impacts product recovery methods on the yields and properties of hydrochar from HTC of algal biomass; and (iv) detailed characterisation of the biocrude and aqueous phase from HTC of algal biomass. The present study aims to address the aforementioned research gaps, with the following specific objectives: (1) to validate the applicability of the conventional proximate analysis methods, which are developed for solid biofuels, for algal biomass, using Spirulina and Chlorella as model algal samples, and then develop an analytical procedure for the proximate analysis of algal biomass; (2) to study the thermo-kinetics of the most plausible reactions encountered during thermal decomposition of ‘Leucine’ as an algal biomass model compound and establish a robust kinetic model accounting for the emission of nitrogen-containing species; (3) to investigate the impact of the product recovery methods on the yield and properties of hydrochar from HTC of Chlorella under the identical reaction conditions; and (4) to characterise the biocrude and aqueous phase from HTC of Chlorella and evaluate the impact of reaction temperature and holding time on the recovery of metals in biocrude and aqueous phase, which is essential for recycling and re-use of these products. These research objectives have been successfully fulfilled in this study, with the key findings outlined below. Firstly, the widely employed ASTM E870–82 designed for woody biomass modified by thermogravimetric analysis (TGA) is found to be inapplicable for the proximate analysis of Spirulina and Chlorella, as indicated by the presence of unburnt carbon and quaternary nitrogen in the resulting ashes, although it accurately determines the contents of volatile matter. While Spirulina can be entirely ashed at 600°C in air, complete oxidation of Chlorella requires the aid of hydrogen peroxide (H2O2) under a similar condition. An analytical procedure is developed for the proximate analysis of algal biomass, using Spirulina and Chlorella as a case study. The procedure consists of three steps: (1) application of the TGA–ASTM E870–82 method to algal biomass followed by observing the colour of the ash residue; (2) direct ashing of algal biomass at 600 ºC in the air to get a fully oxidised ash residue and thereby determine ash content; and (3) oxidation of algal biomass in air at 600 °C for 4 h, with the aid of H2O2. The number of steps required to perform a complete proximate analysis depends on the properties of algal biomass. Secondly, we map out the potential energy surface for a wide array of unimolecular and self-condensation reactions operating in the thermal decomposition of leucine, which was elected as an algal biomass surrogate compound. Decarboxylation, dehydration, and deamination ensue by eliminating CO2, –OH, and NH2, respectively, from α-carbon of leucine. The reaction rate constants indicated comparable branching ratios for decarboxylation and dehydration channels with a minimal contribution from the deamination route. The calculated kinetic parameters served to model a plug-flow reactor that demonstrates species profiles in the gas phase and shows that conversion of leucine attains 100 % in the temperature range 700 – 950 K with a residence time of 10 s. Our kinetics model predicts the formation of isoamylamine (C5H13N), 3-methyl butane-1-imine (C5H11N), 3-methylbutane nitrile (C5H9N), CO2, NH3, H2O, C3H6, and C2H4 as significant products from thermal decomposition of leucine. Kinetic analysis of the plausible channels concluded that the dehydration constitutes the dominant pathway and self-condensation reactions contributed marginally to thermal decomposition of leucine in the gas phase. Thirdly, the hydrochar produced from HTC of Chlorella with 10.0 wt % of solid loading at 180 – 220 °C for holding time of 15 and 60 min was recovered from the batch reactor by two methods that have been commonly employed in literature. The first method involved direct filtration of the product mixture and subsequent drying of the hydrochar, without the use of solvent, whereas the second method used dichloromethane (DCM) to rinse the reactor contents, which recovered hydrochar from the aqueous phase and biocrude, followed by drying of the hydrochar. These two methods are hereafter termed as “direct filtration” and “DCM-aided filtration”, respectively. We found that direct filtration retains heavy biocrude on the hydrochar surface, which results in high mass and energy yields, high carbon levels, low ash contents, low reactivity and improved higher heating values (HHVs) of the hydrochars, in comparison with their counterparts from DCM-aided filtration. The adsorption of biocrude on hydrochar surface leads to blockage of the pores and gives higher intensities of functional groups on the hydrochar surface, both of which strongly influence the retentions of inorganic elements in the hydrochar. Finally, we performed the detailed characterisation of the biocrude and aqueous phase from HTC of Chlorella at 180 – 220 °C for holding time of 15 and 60 min. As the reaction proceeds from mild to severe conditions, mass yield and energy recovery of biocrude increase, and molecular weight distribution of constituent compounds shifts to the smaller size. The highest yield of biocrude was found to be 34.6 wt % on a dry basis of algae at 220 ºC and 60 min with a corresponding heating value of 34.0 MJ/kg. The mass yield of aqueous phase first increases, and then slightly reduces, showing decomposition to biocrude and gaseous products. The relative abundance of N-containing heterocyclic compounds (e.g. 3,6-Diisopropylpiperazin-2,5-dione) in the biocrude increase and oxygenates (such as 1-Hexadecen-3-ol,3,7,11,15-tetramethyl) decrease with an increase of reaction temperature and holding time. The recovery of different metals (Na, K, Mg, Ca, Fe, and Zn) in the biocrude appears to be a strong function of reaction temperature and holding time. For instance, iron in the biocrude decreases from 800.23 to 564.45 mg/kg with an increase in temperature from 180 – 220 °C at 15 min, and a substantial reduction is observed at 60 min (i.e. from 1111.87 to 238.71 mg/kg). The aqueous phase contains most of the essential macronutrients e.g. Na+, K+, CH3COO-, H2PO4- and NH4+, and micronutrients such as Mn, Fe, and Zn, which can be recycled as cultivation media for the growth of algal biomass

The Assessment of Pattern of Injuries Due to Road Traffic Accidents

The increase of the traffic on the roads of Pakistan has drastically increased the rate of accidents. Such accidents have effect on the life of several families as they have lost their family members loved one and faced the long-life disability. Therefore, the current study examines the pattern of injuries due to RTA among the patients of public hospitals so that the root causes and injury types and mortality rate can be assessed. The descriptive and cross-sectional study design have been utilized in this study. The self-administered questionnaire was adopted, and data was collected from 120 patients affected from RTA. The results reveal that the accident rate is high among the males and injury level is moderate. The poor road condition, lack of awareness and poor implementation of traffic rules are the major causes of road traffic accidents. The study also presents the limitations and recommendation at the end

Screening for triazole resistance in clinically significant aspergillus species; report from Pakistan

Background: Burden of aspergillosis is reported to be significant from developing countries including those in South Asia. The estimated burden in Pakistan is also high on the background of tuberculosis and chronic lung diseases. There is concern for management of aspergillosis with the emergence of azole resistant Aspergillus species in neighbouring countries in Central and South Asia. Hence the aim of this study was to screen significant Aspergillus species isolates at the Microbiology Section of Aga Khan Clinical Laboratories, Pakistan, for triazole resistance.Methods: A descriptive cross-sectional study, conducted at the Aga Khan University Laboratories, Karachi, from September 2016-May 2019. One hundred and fourteen, clinically significant Aspergillus isolates [A. fumigatus (38; 33.3%), A. flavus (64; 56.1%), A. niger (9; 7.9%) A. terreus (3; 2.6%)] were included. The clinical spectrum ranged from invasive aspergillosis (IA) (n = 25; 21.9%), chronic pulmonary aspergillosis (CPA) (n = 58; 50.9%), allergic bronchopulmonary aspergillosis (ABPA) (n = 4; 3.5%), severe asthma with fungal sensitization (SAFS) (n = 4; 3.5%), saprophytic tracheobronchial aspergillosis (n = 23; 20.2%). Screening for triazole resistance was performed by antifungal agar screening method. The minimum inhibitory concentration (MIC) of 41 representative isolates were tested and interpreted according to the Clinical and Laboratory Standards Institute broth microdilution method.Results: All the isolates were triazole-susceptible on agar screening. MICs of three azole antifungals for 41 tested isolates were found to be ≤1 ml/L; all isolates tested were categorized as triazole-susceptible, including 4 isolates from patients previously on triazole therapy for more than 2 weeks. The minimum inhibitory concentration required to inhibit the growth of 90% organisms (MIC90) of itraconazole, voriconazole and posaconazole of the representative Aspergillus isolates was 1 mg/L, 1 mg/L and 0.5 mg/L, respectively.Conclusion: Triazole resistance could not be detected amongst clinical Aspergillus isolates from the South of Pakistan. However, environmental strains remain to be tested for a holistic assessment of the situation. This study will set precedence for future periodic antifungal resistance surveillance in our region on Aspergillus isolates

Characterization of cypermethrin degrading bacteria: A hidden micro flora for biogeochemical cycling of xenobiotics

 Background: Cypermethrin is a Synthetic Pyrethroid (SP) having widespread applications in agriculture and industrial sector especially in sheep dip formulations and tanneries. Rhizoremediation offers a sustainable, environment-friendly and cost-effective means to carry out remediation of contaminated soils.Methods: Six bacterial strains were screened out and characterized at various doses of cypermethrin, heavy metal salts and antibiotics. The optimum growth conditions were determined for these bacterial isolates. The degradation of cypermethrin was confirmed through the growth of bacteria on minimal media (BHB) with cypermethrin and thin layer chromatographic analysis; retention factor values (Rf) were calculated and compared with standard Rf values.Results: Growth curve experiments revealed that three bacterial isolates were able to grow in the presence of cypermethrin. Tolerance to the high concentration of heavy metal salts (300µgmL-1) and resistance towards different antibiotics was observed in all three bacterial isolates indicating a positive correlation between pesticide degradation and tolerance to metals and antibiotics. Bacterial strains A-C1 and B-B2 were identified as Xanthomonas maltophilia and B-C2 as Acinetobacter sp. Cypermethrin degradation occurred concomitant with bacterial growth reaching an optical density (OD600) up to 0.869.Conclusion: Microbes present in rhizosphere have potential to mineralize the pesticides. A significant biodegradation of the cypermethrin was observed based on above mentioned lab parameters. These results paved the way for designing a multi-resistant bacterium that can be used to reverse the altered environment

Effect Of Zinc And Ingredients Of Protein Supplement On Sperm Parameters And Male Reproductive Hormones- An RCT Study

Abstract Objective: The purpose of this study was to assess the protective effects of zinc against injury to sperm parameters and male reproductive hormones brought on by toxic protein supplement constituents. Methods: 30 male Sprague Dawley rats were used in the study, of which 10 were in Group 1 (given standard laboratory food), 10 were in Group 2, fed standard laboratory food nutritional supplement powder and 10 were in Group 3, fed standard laboratory food, nutritional supplement powder and zinc. Semen Analysis of Male Sprague Dawley rats of all 3 groups was evaluated after 8 weeks. Sperm parameters and serum levels of Male Reproductive Hormones were measured at the beginning and the end of the study. Results: There was a significant decrease (P<0.05) in Mean ± SEM of sperm count millions /ml, sperm motility (%), and normal sperm morphology (%) in Group 2 rats when compared with Group 1. Zinc supplement in Group 3 caused a significant increase (P<0.05) in Mean ± SEM of sperm parameters including sperm count millions /ml, sperm motility (%) and normal sperm morphology (%) as compared to Group 2 rats. Mean ± SEM of serum level of testosterone Hormone, Follicle Stimulating Hormone(FSH), and Luteinizing Hormone(LH) of Group 2 rats showed a significant (P<0.05) decrease when compared with Group 1 rats. However, the use of Zinc in Group 3 rats significantly (P<0.05) increased serum Testosterone, FSH, and LH levels when compared to Group 2. No significant difference was noted between serum levels of Testosterone, in Group 1 and Group 3. Serum levels of FSH and LH in Group 3 rats (484.81+ 78.17 ng/ml) were significantly increased (P<0.05) as compared to Group 1 rats. Conclusion: Regular addition of antioxidant Zinc with protein supplements has the potential to restore normal functions of the male reproductive system.

Kinetic & Equilibrium Modelling of Copper Biosorption

A thorough examination focused around  linear and non-linear regression of various kinetic models (Pseudo 1st Order and Pseudo 2nd Order), two parameter isotherm models (Freundlich, Langmuir, Tempkin, Duninin-Radushjevich and Hill) and three parameter isotherm models (Redlich-Peterson, Radke-Prausnitz, Koble-Corrigan, Sips and Toth) were analyzed to investigate different aspects of Cu(II) biosorption onto dead immobilized Rhizopus Arrhizus (DIRA). Batch sorption studies were made at 30±2 ºC and Optimum pH for Cu (II) biosorption on DIRA was 6.5. Coefficient of determination (R2) was utilized to demonstrate the integrity of the fit of a model. Sum of the square of the errors (SSE), mean square error (MSE), root mean square error (RMSE), sum of the absolute error (SAE) and average relative error (ARE) were likewise utilized. Non-linear method found to be more proper technique for getting parameters. Based on R2, SSE, MSE, RMSE, SAE and ARE among two parameters models Langmuir isotherm enumerated the experimental data best and among three parameters models Redlich-Peterson & Radke-Prausnitz isotherm models gave the best depiction of the work directed. Pseudo 2nd order kinetic enumerated the biosorption of Cu+2 using DIRA best

Spiritual Leadership in Organizational Context: A Research Gap in South Asia

There is an emerging research area related to vision, hope, faith and intrinsic motivation as ―spiritual leadership‖. Researchers are presently in quest of publication channels as knockers argue whether this novel leadership theory is ominously discrete, practical, and valued for organizational triumph. The purpose of this research was to find research studies that discovered ―spiritual leadership‖ theory to evaluate and produce the instruments, dimensions, consequences, and effects of ―spiritual leadership‖. Therefore, we pursued to offer an evidence well-versed solution that by what means ―spiritual leadership‖ work, and in what way can we put on it? We led a ―SLR‖ (Systematic Literature Review), an approach embraced from the medicinal disciplines to synthesize research in an organized, clear, and reproducible way. A well-organized screening procedure stemmed in an ultimate sample population of 62 fitting research studies. The synthesis of these empirical research studies shown: (a) there is no agreement on the definition of ―spiritual leadership‖ (b) The investigation discloses that there are merely three frequently cited (73%) dimensions which have been verified empirically by means of both Quantitative and Qualitative Methods. These are Altruistic Love, Hope and Faith proposed by Fry et al 2003; 2005; 2008 (Table 3). Rest of the 27% dimensions have been least tested empirically and cited. (c) Empirical authentication of ―spiritual leadership‖ models other than Fry 2003; 2005; 2008 which are contributing 27% of empirical and 75% of the conceptual/review studies needs to be done in establishments like schools, cities, police, military units, and for profit officialdoms with numerous sample dimensions for authentication of these models (d) ―Spiritual Leadership‖ theory is being examined crossways in a diversity of settings and cultures but there is a significant research gap in this area of research (where the Spiritual Leadership is being studied in organizational contexts) in South Asian countries including Pakistan India, and Sri Lanka etc. (e) ―spiritual leadership‖ is a practical leadership theory that aids organizations and mends the well-being of groups. This scholarship backs to the advancement of ―spiritual leadership‖ notion and practice. Also, this scholarship contributes to the practice for piloting Systematic Literature Reviews in the arena of management, stressing an operative process for plotting out thematically, and inspecting holistically, novel research themes

Higher Sensitivity of Female Cells to Ethanol: Methylation of DNA Lowers Cyp2e1, Generating more ROS

Background: Cells taken from mouse embryos before sex differentiation respond to insults according to their chromosomal sex, a difference traceable to differential methylation. We evaluated the mechanism for this difference in the controlled situation of their response to ethanol. Methods: We evaluated the expression of mRNA for alcohol dehydrogenase (ADH), aldehyde dehyrogenases (ALDH), and a cytochrome P450 isoenzyme (Cyp2e1) in male and female mice, comparing the expressions to toxicity under several experimental conditions evaluating redox and other states. Results: Females are more sensitive to ethanol. Disulfiram, which inhibits alcohol dehydrogenase (ADH), increases cell death in males, eliminating the sex dimorphism. The expressions ADH Class 1 to 4 and ALDH Class 1 and 2 do not differ by sex. However, females express approximately 8X more message for Cyp2e1, an enzyme in the noncanonical pathway. Female cells produce approximately 15% more ROS (reactive oxygen species) than male cells, but male cells contain approximately double the concentration of GSH, a ROS scavenger. Scavenging ROS with Nacetyl cysteine reduces cell death and eliminates sex dimorphism. Finally, since many of the differences in gene expression derive from methylation of DNA, we exposed cells to the methyltransferase inhibitor 5-aza- 2- deoxycytidine; blocking methylation eliminates both the difference in expression of Cyp2e1 and cell death. Conclusion: We conclude that the sex-differential cell death caused by ethanol derives from sex dimorphic methylation of Cyp2e1 gene, resulting in generation of more ROS. Keywords: Sex differences, Cyp450, ROS, Cell death, Methylatio

Anatomical success of tectonic keratoplasty in children at a tertiary care eye hospital

Objective: To evaluate the anatomical outcome of tectonic grafts performed in children with perforated or melted corneas. Method: The prospective study was conducted at the Department of Paediatric Ophthalmology, Al-Shifa Trust Eye Hospital, Rawalpindi, Pakistan, from January to December 2017, and comprised children of either gender aged 3mm.  The causes of corneal perforation, size of perforation, post-operative graft outcome and globe integrity were noted. Periodic follow-ups were done till December 2019. Data was analysed using SPSS 22. Results: Of the 27 patients, 9(33.3%) were girls and 18(66.7%) were boys. The overall mean age was 47.7±43.5 months. The most common indication was corneal perforation 19(70.4%), followed by descemetocele 8(29.6%). The most frequent cause was infectious keratitis 13(48.2%), followed by trauma 8(29.6%) and vitamin A deficiency 5(18.5%). The mean size of perforation/descemetocele was 5.5±1.5mm. Post-operatively, graft failure occurred in 5(18.5%) eyes and required repeat grafts. Globe integrity was restored in all 27(100%) cases, and 24(88.8%) eyes maintained their size and intraocular pressure, while 3(11.1%) became phthisical. Post-operative visual acuity was better than 6/36 in 3(11.1%) eyes, between 6/36 and 6/60 in 10(37%) and counting finger in 14(51.8%). Conclusion: Tectonic graft was found to be a valuable therapeutic option in emergency globe-threatening corneal thinning and perforation and in maintaining the anatomical integrity of eyes. Key Words: Keratoplasty, Corneal perforation, Corneal grafting