The role of biochar, natural iron oxides, and nanomaterials as soil amendments for immobilizing metals in shooting range soil

Rajapaksha, A. U.,Ahmad, M.,Vithanage, M.,Kim, K. R.,Chang, J. Y.,Lee, S. S.,Ok, Y. S. Springer Science + Business Media 2015 Environmental geochemistry and health Vol.37 No.6

<P>High concentration of toxic metals in military shooting range soils poses a significant environmental concern due to the potential release of metals, such as Pb, Cu, and Sb, and hence requires remediation. The current study examined the effectiveness of buffalo weed (Ambrosia trifida L.) biomass and its derived biochars at pyrolytic temperatures of 300 and 700 A degrees C, natural iron oxides (NRE), gibbsite, and silver nanoparticles on metal immobilization together with soil quality after 1-year soil incubation. Destructive (e.g., chemical extractions) and non-destructive (e.g., molecular spectroscopy) methods were used to investigate the immobilization efficacy of each amendment on Pb, Cu, and Sb, and to explore the possible immobilization mechanisms. The highest immobilization efficacy was observed with biochar produced at 300 A degrees C, showing the maximum decreases of bioavailability by 94 and 70 % for Pb and Cu, respectively, which were attributed to the abundance of functional groups in the biochar. Biochar significantly increased the soil pH, cation exchange capacity, and P contents. Indeed, the scanning electron microscopic elemental dot mapping and X-ray absorption fine structure spectroscopic (EXAFS) studies revealed associations of Pb with P (i.e., the formation of stable chloropyromorphite [Pb-5(PO4)(3)Cl]) in the biomass- or biochar-amended soils. However, no amendment was effective on Sb immobilization.</P>

Development of PCR Assay for Identification of Buffalo Meat

Rajapaksha, W.R.A.K.J.S.,Thilakaratne, I.D.S.I.P.,Chandrasiri, A.D.N.,Niroshan, T.D. Asian Australasian Association of Animal Productio 2003 Animal Bioscience Vol.16 No.7

A polymerase chain reaction (PCR) assay was developed to differentiate buffalo meat from the meat of Ceylon spotted deer (Axis axis ceylonensis), Ceylon sambhur (Cervus unicolor unicolor), cattle (Bovine), goat (Caprine), pig (Porcine), and sheep (Ovine). A set of primers were designed according to the sequence of the mitochondrial cytochrome b gene of bubalus bubalis and by PCR amplification a band of approximately 242 bp band was observed with buffalo DNA. These primers did not cross-react with DNA of other animal species tested in the study under the specified reaction conditions. A band of 649 bp was observed for all animal species tested when DNA was amplified with the universal primers indicating the presence of mitochondrial DNA in the samples. The technique was sensitive enough to identify rotten (10 days post slaughter), dried and cooked buffalo meat. The absence of a cross reaction with human DNA using the buffalo specific primers eliminates possible false positive reactions.

Shikonin Isolated from Lithospermum erythrorhizon Downregulates Proinflammatory Mediators in Lipopolysaccharide-Stimulated BV2 Microglial Cells by Suppressing Crosstalk between Reactive Oxygen Species and NF-κB

( Rajapaksha Gedara Prasad ),( Yung Hyun Choi ),( Gi Young Kim ) 한국응용약물학회 2015 Biomolecules & Therapeutics(구 응용약물학회지) Vol.23 No.2

According to the expansion of lifespan, neuronal disorder based on inflammation has been social problem. Therefore, we isolated shikonin from Lithospermum erythrorhizon and evaluated anti-inflammatory effects of shikonin in lipopolysaccharide (LSP)- stimulated BV2 microglial cells. Shikonin dose-dependently inhibits the expression of the proinflammatory mediators, nitric oxide (NO), prostaglandin E2 (PGE2), and tumor necrosis factor-α (TNF-α) as well as their main regulatory genes and products such as inducible NO synthase (iNOS), cyclooxygenase-2 (COX-2), and TNF-α in LPS-stimulated BV2 microglial cells. Additionally, shikonin suppressed the LPS-induced DNA-binding activity of nuclear factor-κB (NF-κB) to regulate the key regulatory genes of the proinflammatory mediators, such as iNOS, COX-2, and TNF-α, accompanied with downregulation of reactive oxygen species (ROS) generation. The results indicate that shikonin may downregulate the expression of proinflammatory genes involved in the synthesis of NO, PGE2, and TNF-α in LPS-treated BV2 microglial cells by suppressing ROS and NF-κB. Taken together, our results revealed that shikonin exerts downregulation of proinflammatory mediators by interference the ROS and NF-κB signaling pathway.

Cr(VI) Formation Related to Cr(III)-Muscovite and Birnessite Interactions in Ultramafic Environments

Rajapaksha, Anushka Upamali,Vithanage, Meththika,Ok, Yong Sik,Oze, Christopher American Chemical Society 2013 Environmental science & technology Vol.47 No.17

<P>Chromium is abundantly and primarily present as Cr(III) in ultramafic rocks and serpentine soils. Chromium(III) oxidation involving chromite (FeCr<SUB>2</SUB>O<SUB>4</SUB>) via interactions with birnessite has been shown to be a major pathway of Cr(VI) production in serpentine soils. Alternatively, Cr(III)-bearing silicates with less Cr(III) may provide higher Cr(VI) production rates compared to relatively insoluble chromite. Of the potential Cr(III)-bearing silicates, Cr(III)-muscovite (i.e., fuchsite) commonly occurs in metamorphosed ultramafic rocks and dissolution rates may be comparable to other common Cr(III)-bearing phyllosilicates and clays. Here, we examine the formation of Cr(VI) related to Cr(III)-muscovite and birnessite (i.e., acid birnessite) interactions with and without humic matter (HM) via batch experiments. Experimentally, the fastest rate of Cr(VI) production involving Cr(III)-muscovite was 3.8 × 10<SUP>–1</SUP> μM h<SUP>–1</SUP> (pH 3 without HM). Kinetically, Cr(III)-muscovite provides a major pathway for Cr(VI) formation and Cr(VI) production rates may exceed those involving chromite depending on pH, available mineral surface areas in solution, and the abundance of Cr(III) present. However, when HM is introduced to the system, Cr(VI) production rates decrease by as much as 80%. This highlights that HM strongly decreases but may not completely suppress the formation and mobilization of Cr(VI). A Sri Lankan serpentine soil was utilized to provide context with regards to the experimental results. Despite Cr(VI) in the soil solids and Cr(VI) formation being favorable from Cr(III)-bearing minerals, no detectable Cr(VI) was released into soil solutions potentially due to the abundance of HM. Overall, the dynamic interactions of Cr(III)-bearing silicates and birnessite provide a kinetically favorable route of Cr(VI) formation which is tempered by humic matter.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/esthag/2013/esthag.2013.47.issue-17/es4015025/production/images/medium/es-2013-015025_0006.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/es4015025'>ACS Electronic Supporting Info</A></P>

Removal of hexavalent chromium in aqueous solutions using biochar: Chemical and spectroscopic investigations

Rajapaksha, Anushka Upamali,Alam, Md. Samrat,Chen, Ning,Alessi, Daniel S.,Igalavithana, Avanthi Deshani,Tsang, Daniel C.W.,Ok, Yong Sik Elsevier BV 2018 Science of the Total Environment Vol.625 No.-

<P><B>Abstract</B></P> <P>Biochar is an emerging low-cost sorbent used for removing trace metals from water. In this study, we evaluated the removal potential of aqueous hexavalent chromium (Cr(VI)) by biochars produced from soybean (<I>Glycine</I> <I>max</I> L.) and burcucumber (<I>Sicyos angulatus</I> L.) residues. The highest Cr(VI) removal from solution occurred at low pH values (pH2–5), and adsorption decreased approximately tenfold when the pH increased from 2 to 10. Synchrotron-based X-ray absorption spectroscopy (XAS) investigations showed that Cr(VI) species were reduced to trivalent chromium (Cr(III)) at the biochar surface following Cr(VI) adsorption. Linear combination fitting (LCF) of X-ray absorption near edge structure (XANES) data indicated that approximately 90% of the total Cr(VI) (962μM) was reduced to Cr(III). Extended X-ray absorption fine structure (EXAFS) fitting results yielded interatomic chromium (CrCr) distances consistent with the formation of Cr(III) precipitates as Cr(OH)<SUB>3</SUB>. Trivalent chromium is far less soluble than Cr(VI) and typically precipitates as amorphous Cr(III) solids. Thus, biochars produced by soybean and burcucumber residues are a promising technique for both adsorbing and reductively immobilizing Cr(VI) from aqueous solutions.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Removal potential of aqueous Cr(VI) by biochar was evaluated. </LI> <LI> The highest Cr(VI) removal occurred at low pH values. </LI> <LI> Cr(VI) species can be reduced to Cr(III) at the biochar surface. </LI> <LI> Biochar properties determine the coordination environment of Cr(III) products. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Steam activation of biochars facilitates kinetics and pH-resilience of sulfamethazine sorption

Rajapaksha, A. U.,Vithanage, M.,Lee, S. S.,Seo, D. C.,Tsang, D. C.,Ok, Y. S. Springer Science + Business Media 2016 Journal of soils and sediments Vol.16 No.3

<P>Sulfamethazine (SMT) is increasingly detected in environmental matrices due to its versatile use as antibiotics. We aimed to investigate the benefits and roles of steam activation of biochars with respect to SMT sorption kinetics and equilibrium sorption. Biochars were produced from burcucumber plant and tea waste using a pyrolyzer at a temperature of 700 A degrees C for 2 h. The biochar samples were treated with 5 mL min(-1) of steam for an additional 45 min for post-synthesis steam activation. The SMT sorption on the unmodified and steam activated biochars were compared. The time taken to reach equilibrium was significantly less for steam activated biochars (similar to 4 h) than non-activated biochars (> 24 h). Up to 98 % of SMT could be removed from aqueous solutions by steam activated biochars. The sorption kinetic behaviors were well described by the pseudo-second model and SMT sorption rates of steam activated biochars (k (2) similar to aEuro parts per thousand 1.11-1.57 mg g(-1) min(-1)) were significantly higher than that of the unmodified biochars (k (2) similar to aEuro parts per thousand 0.04-0.11 mg g(-1) min(-1)) because of increased availability of accessible porous structure with averagely larger pore diameters. Moreover, the equilibrium sorption on the unmodified biochars was significantly influenced by increasing solution pH (similar to 30-50 % reduction) because of speciation change of SMT, whereas steam activated biochars manifested much stronger sorption resilience against pH variation (similar to 2-4 % reduction only) because the enhanced porosity offset the effect of unfavorable electrostatic repulsion. The observed features of steam activated biochars would render their applications more versatile and reliable in field throughout changeable environmental conditions.</P>

Camptothecin enhances c-Myc-mediated endoplasmic reticulum stress and leads to autophagy by activating Ca²⁺-mediated AMPK

Jayasooriya, Rajapaksha Gedara Prasad Tharanga,Dilshara, Matharage Gayani,Karunarathne, Wisurumuni Arachchilage Hasitha Maduranga,Molagoda, Ilandarage Menu Neelaka,Choi, Yung Hyun,Kim, Gi-Young Elsevier 2018 Food and chemical toxicology Vol.121 No.-

<P><B>Abstract</B></P> <P>Camptothecin (CPT) from <I>Camptotheca acuminate</I> was discovered for anticancer drugs, which targets topoisomease I. However, whether CPT regulates c-Myc expression has not been understood in endoplasmic reticulum (ER) stress and autophagy. In this study, we found that CPT enhanced c-Myc expression and that the transient knockdown of <I>c-Myc</I> abrogated reactive oxygen species (ROS) generation, which resulted in the accumulation of ER stress-regulating proteins, such as PERK, eIF2α, ATF4, and CHOP. Moreover, the transfection of <I>eIF2α</I>-targeted siRNA attenuated CPT-induced autophagy and decreased the levels of Beclin-1 and Atg7, which indicated that CPT upregulated ER stress-mediated autophagy. In addition, CPT phosphorylated AMPK in response to intracellular Ca<SUP>2+</SUP> release. Ca<SUP>2+</SUP> chelators, ethylene glycol tetraacetic acid and a CaMKII inhibitor, K252a, decreased CPT-induced Beclin-1 and Atg7, and downregulated AMPK phosphorylation, which suggested that CPT-induced Ca<SUP>2+</SUP> release leads to the activation of autophagy through CaMKII-mediated AMPK phosphorylation. CPT also phosphorylated JNK and activated the DNA-binding activity of AP-1; furthermore, knockdown of <I>JNK</I> abolished the expression level of Beclin-1 and Atg7, which implied that the JNK-AP-1 pathway was a potent mediator of CPT-induced autophagy. Our findings indicated that CPT promoted c-Myc-mediated ER stress and ROS generation, which enhances autophagy via the Ca<SUP>2+</SUP>-AMPK and JNK-AP-1 pathways.</P> <P><B>Highlights</B></P> <P> <UL> <LI> CPT induces c-Myc-mediated ROS formation, leading to CHOP expression. </LI> <LI> c-Myc positively regulates CPT-induced ER stress by increasing ROS generation. </LI> <LI> CPT promotes autophagy formation as a result of ER stress. </LI> <LI> CPT promotes autophagy through increased intracellular Ca2+ release. </LI> <LI> CPT induces JNK-mediated autophagy by enhancing AP-1 activity. </LI> </UL> </P>

Analysis of electrochemical double-layer capacitors using a Natural Rubber-Zn based polymer electrolyte

Nanditha Rajapaksha,Kumudu S. Perera,Kamal P. Vidanapathirana Techno-Press 2022 Advances in energy research Vol.8 No.1

Electrochemical double-layer capacitors (EDLCs) based on solid polymer electrolytes (SPEs) have gained an immense recognition in the present world due to their unique properties. This study is about preparing and characterizing EDLCs using a natural rubber (NR) based SPE with natural graphite (NG) electrodes. NR electrolyte was consisted with 49% methyl grafted natural rubber (MG49) and zinc trifluoromethanesulfonate ((Zn(CF₃SO₃)₂-ZnTF). It was characterized using electrochemical impedance spectroscopy (EIS) test, dc polarization test and linear sweep voltammetry (LSV) test. NG electrodes were made using a slurry of NG and acetone. EIS test, cyclic voltammetry (CV) test and galvanostatic charge discharge (GCD) test have been done to characterize the EDLC. Optimized electrolyte composition with NR: 0.6 ZnTF (weight basis) exhibited a conductivity of 0.6 x 10^-4 Scm^-1 at room temperature. Conductivity was predominantly due to ions. The electrochemical stability window was found to be from 0.25 V to 2.500 V. Electrolyte was sandwiched between two identical NG electrodes to fabricate an EDLC. Single electrode specific capacitance was about 2.26 Fg^-1 whereas the single electrode discharge capacitance was about 1.17 Fg^-1. The EDLC with this novel NR-ZnTF based SPE evidences its suitability to be used for different applications with further improvement.

Combined treatment with verrucarin A and tumor necrosis factor-α sensitizes apoptosis by overexpression of nuclear factor-kappaB-mediated Fas

Jayasooriya, Rajapaksha Gedara Prasad Tharanga,Moon, Dong-Oh,Park, Sang Rul,Choi, Yung Hyun,Asami, Yukihiro,Kim, Mun-Ock,Jang, Jae-Hyuk,Kim, Bo Yeon,Ahn, Jong Seog,Kim, Gi-Young Elsevier 2013 Environmental toxicology and pharmacology Vol.36 No.2

<P><B>Abstract</B></P> <P>Verrucarin A (VA) is a member of the family of macrocyclic trichothecenes, which exhibit anti-cancer and immune-modulating activities. However, VA has not yet been demonstrated to be involved in the sensitization of tumor necrosis factor-alpha (TNF-α)-mediated apoptosis. In the present study, we found that VA triggers TNF-α-induced apoptosis in human breast cancer MDA-MB-231 and MCF-7 cells. In particular, activation of caspas-3 and caspase-8 as well as release of cytochrome <I>c</I> were significantly enhanced in response to the combined treatment with VA and TNF-α (VA/TNF-α) and the pan-caspase inhibitor z-VAD-fmk completely reversed the apoptosis, suggesting that caspases are the main effector molecules in VA/TNF-α-induced apoptosis via the intrinsic and extrinsic pathway. Moreover, we confirmed that enhanced Fas expression plays a critical role, because the Fas-blocking antibody partially inhibited VA/TNF-α-induced apoptosis. VA also increased specific DNA-binding activity of nuclear factor-kappaB (NF-κB) via nuclear translocation of p50 and p65. In addition, pretreatment with the NF-κB inhibitor MG132 blocked VA/TNF-α-induced apoptosis by suppression of NF-κB-dependent Fas expression. These results indicated that VA enhances TNF-α-induced apoptosis via NF-κB-dependent Fas overexpression.</P> <P><B>Highlights</B></P> <P> <UL> <LI> VA sensitizes TNF-α-induced apoptosis in human breast cancer cells. </LI> <LI> VA enhances TNF-α-dependent nuclear translocation of p50 and p65. </LI> <LI> VA/TNF-α triggers NF-κB-dependent Fas-induced cell death. </LI> </UL> </P>

Fulvic acid promotes extracellular anti-cancer mediators from RAW 264.7 cells, causing to cancer cell death <i>in vitro</i>

Jayasooriya, Rajapaksha Gedara Prasad Tharanga,Dilshara, Matharage Gayani,Kang, Chang-Hee,Lee, Seungheon,Choi, Yung Hyun,Jeong, Yong Kee,Kim, Gi-Young Elsevier 2016 INTERNATIONAL IMMUNOPHARMACOLOGY Vol.36 No.-

<P><B>Abstract</B></P> <P>Fulvic acid (FA) is known to promote electrochemical balance as a donor or a receptor possessing many biomedical functions. Nevertheless, the effect of FA on the anti-cancer activity has not been elucidated. In the current study, we first isolated FA from humus and investigated whether FA regulates immune-stimulating functions, such as production of nitric oxide (NO), in RAW 264.7 cells. Our data showed that FA slightly enhances cell viability in a dose-dependent manner and secretion of NO from RAW 264.7 cells. It upregulated the protein and mRNA expression of inducible NO synthesis (iNOS). In addition, FA enhanced the DNA-binding activity of nuclear factor-κB (NF-κB) in RAW 264.7 cells; the NF-κB inhibitor, pyrrolidine dithiocarbamate (PDTC) effectively attenuated the expression of FA-stimulated iNOS, suggesting that FA stimulates NF-κB to promote iNOS and NO production. Finally, FA-stimulated culture media (FA-CM) from RAW 264.7 cells were collected and MCA-102 fibrosarcoma cells were cultured in this media. The FA-CM augmented MCA-102 fibrosarcoma cell apoptosis; however, an NO inhibitor <I>N</I> <SUP>G</SUP>-monomethyl-<SMALL>L</SMALL>-arginine (NMMA) slightly inhibited the FA-CM-mediated MCA-102 fibrosarcoma cell apoptosis, which was accompanied by low levels of NO. In the present study, we found that FA induces the generation of NO and iNOS in RAW 264.7 cells by inducing NF-κB activation; however, NO did not significantly stimulate MCA-102 fibrosarcoma cell apoptosis in the current study. In addition, FA-CM enhanced cell death in various human cancer cells such as Hep3B, LNCaP, and HL60. Taken together, FA most likely stimulates immune-modulating molecules such as NO and induces cancer cell apoptosis.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Fulvic acid is isolated from humus by acid-base extraction methods. </LI> <LI> Fulvic acid increases proliferation of RAW 264.7 macrophage cells. </LI> <LI> Fulvic acid upregulates the expression of <I>iNOS</I> and NO by inducing NF-κB activity. </LI> <LI> Fulvic acid-stimulated medium of RAW 264.7 macrophages increases apoptosis of MCA-102 fibrosarcoma cells. </LI> </UL> </P>