Effect of compaction on bisulfide diffusive transport through MX-80 bentonite

Canada's deep geological repository (DGR) design includes an engineered barrier system where highly compacted bentonite (HCB) surrounds the copper-coated used fuel containers (UFCs). Microbial-influenced corrosion is a potential threat to long-term integrity of UFC as bisulfide (HS-) may be produced by microbial activities under anaerobic conditions and transported via diffusion through the HCB to reach the UFC surface, resulting in corrosion of copper. Therefore, understanding HS- transport mechanisms through HCB is critical for accurate prediction of copper corrosion allowance. This study investigated HS- transport behaviour through MX-80 bentonite at dry densities 1070-1615 kg m-3 by performing through-diffusion experiments. Following HS- diffusion, bromide (Br-) diffusion and Raman spectroscopy analyses were performed to explore possible physical or mineralogical alterations of bentonite caused by interacting with HS-. In addition, accessible porosity ε was estimated using extended Archie's law. Effective diffusion coefficient of HS- was found 2.5 × 10-12 m2 s-1 and 5.0× 10-12 m2 s-1 for dry densities 1330 and 1070 kg m-3, respectively. No HS- breakthrough was observed for highly compacted bentonite (1535-1615 kg m-3) over the experimental timeframe (170 days). Raman spectroscopy results revealed that HS- reacted with iron in bentonite and precipitated as mackinawite and, therefore, it was immobilized. Finally, results of this study imply that HS- transport towards UFC will be highly controlled by the available iron content and dry density of the buffer material.

Visible light-based 3D bioprinted composite scaffolds of κ-carrageenan for bone tissue engineering applications

Three-dimensional (3D) printing of bone scaffolds using digital light processing (DLP) bioprinting technology empowers the treatment of patients suffering from bone disorders and defects through the fabrication of cell-laden patient-specific scaffolds. Here, we demonstrate the visible-light-induced photo-crosslinking of methacrylate-κ-carrageenan (MA-κ-CA) mixed with bioactive silica nanoparticles (BSNPs) to fabricate 3D composite hydrogels using digital light processing (DLP) printing. The 3D printing of complex bone structures, such as the gyroid, was demonstrated with high precision and resolution. DLP-printed 3D composite hydrogels of MA-κ-CA-BSNP were prepared and systematically assessed for their macroporous structure, swelling, and degradation characteristics. The viscosity, rheological, and mechanical properties were also investigated for the influence of nanoparticle incorporation in the MA-κ-CA hydrogels. The in vitro study performed with MC3T3-E1 pre-osteoblast-laden scaffolds of MA-κ-CA-BSNP revealed high cell viability, no cytotoxicity, and proliferation over 21 days with markedly enhanced osteogenic differentiation compared to neat polymeric scaffolds. Furthermore, no inflammation was observed in the 21-day study involving the in vivo examination of DLP-printed 3D composite scaffolds in a Wistar rat model. Overall, the observed results for the DLP-printed 3D composite scaffolds of MA-κ-CA and BSNP demonstrate their biocompatibility and suitability for bone tissue engineering.

Injectable Adhesive Hydrogels for Soft tissue Reconstruction: A Materials Chemistry Perspective

Injectable bioadhesives offer several advantages over conventional staples and sutures in surgery to seal and close incisions or wounds. Despite the growing research in recent years few injectable bioadhesives are available for clinical use. This review summarizes the key chemical features that enable the development and improvements in the use of polymeric injectable hydrogels as bioadhesives or sealants, their design requirements, the gelation mechanism, synthesis routes, and the role of adhesion mechanisms and strategies in different biomedical applications. It is envisaged that developing a deep understanding of the underlying materials chemistry principles will enable researchers to effectively translate bioadhesive technologies into clinically-relevant products.

Light-based 3D bioprinting of bone tissue scaffolds with tunable mechanical properties and architecture from photocurable silk fibroin

Three-dimensional (3D) bioprinting based on digital light processing (DLP) offers unique opportunities to prepare scaffolds that mimic the architecture and biomechanical properties of human tissues. Limited availability of biocompatible and biodegradable bioinks amenable for DLP-bioprinting is an impediment in this field. This study presents a bioink prepared from silk fibroin (SF) tailored for DLP bioprinting. Photocurable methacrylated-SF (SF-MA) was synthesized with 67.3% of methacrylation. Physical characterization of rheological and mechanical properties revealed that the 3D printed hydrogels of SF-MA (spanning from 10 to 25 wt%) exhibit bone tissue-like viscoelastic behavior and compressive modulus ranging from ≈12 kPa to ≈96 kPa. The gels exhibited favorable degradation (≈48 to 91% in 21 days). This SF-MA bioink afforded the printing of complex structures, with high precision. Pre-osteoblasts were successfully encapsulated in 3D bioprinted SF-MA hydrogels with high viability. 15% SF-MA DLP bioprinted hydrogels efficiently supported cell proliferation with favorable cell morphology and cytoskeletal organization. A progressive increase in cell-mediated calcium deposition up to 14 days confirmed the ability of the gels to drive osteogenesis, which was further augmented by soluble induction factors. This work demonstrates the potential of silk fibroin-derived bioinks for DLP-based 3D bioprinting of scaffolds for tissue engineering.

Production of lipid-containing microalgal biomass and simultaneous removal of nitrate and phosphate from synthetic wastewater

The major concerns of the modern society such as increasing population, climate change and economic development are imposing continuous stress on water and energy resources. The present work deals with the cultivation of green algae Desmodesmus abundans for optimum biomass productivity and lipid content as well as simultaneous removal of nitrate and phosphate from synthetic wastewater. The algal biomass is characterized by ultimate analysis, scanning electron microscopic analysis and thermogravimetric analysis. The effect of time, inoculum concentration and nitrate concentration on four responses (biomass productivity, lipid content, removal of nitrate and removal of phosphate) are studied by response surface methodology using central composite design. The quadratic models are found to be suitable for each response. At optimized experimental conditions, the algae showed biomass productivity of 46.96 mg L^-1 day^-1, lipid content of 16.23%, nitrate removal of 86.64% and phosphate removal of 87.52% after 27 days, when the initial inoculum concentration was 6% and nitrate concentration was 1.25 g L^-1.

Recent advancements and new perspectives in animal models for Neurocysticercosis immunopathogenesis

Neurocysticercosis (NCC), one of the most common parasitic diseases of the central nervous system, is caused by Taenia solium. This parasite involves two hosts, intermediate hosts (pig and human) and a definitive host (human) and has various stages in its complex life cycle (eggs, oncosphere, cysticerci and adult tapeworm). Hence, developing an animal model for T. solium that mimics its natural course of infection is quite challenging. We have reviewed here the animal models frequently used to study immunopathogenesis of cysticercosis and also discussed their usefulness for NCC studies. We found that researchers have used mice, rats, guinea pigs, dogs, cats and pigs as models for this disease with varying degrees of success. Mice and rats models have been utilized extensively for immunopathogenesis studies due to their relative ease of handling and abundance of commercially available reagents to study these small animal models. These models have provided some very exciting results for in-depth understanding of the disease. Of late, the experimentally/naturally infected swine model is turning out to be the best animal model as the disease progression closely resembles human infection in pigs. However, handling large experimental animals has its own challenges and limitations.

Direct experimental observation of salt induced aspect ratio tunable PFPT silver-nanowire formation: SERS-based ppt level Hg2+ sensing from ground water

A common salt induced aspect ratio tunable PFPT silver nanowire synthesis with a plausible explanation based on real-time direct experimental observation finds application as a potential assay for ppt level Hg(ii) sensing from ground water.

Hyper-Rayleigh scattering from gold nanoparticles: effect of size and shape

We report hyper-Rayleigh scattering (HRS) properties of gold nanoparticles (GNPs) of five different shapes, quasi-spherical (∼10 and ∼20 nm diameter), rod (aspect ratio ∼2), and branched shapes, tetrapod, flower and star with 800 nm, 150 fs laser excitation. Using ∼10 nm spherical GNPs as reference, the first hyperpolarizability (β) values were calculated for all other shapes. Star and flower shaped GNPs have the highest hyperpolarizability (∼130 and ∼52 times higher, respectively), while rod and tetrapod shaped GNPs only have modest enhancement (∼7 times), which is similar to ∼20 nm size quasi-spherical particles. These enhancements are attributed to reduced symmetry as well as the presence of sharp tips on GNP surface. When the β values are normalized with respect to the number of atoms per particle, the flower and star shaped GNPs still have the highest hyperpolarizability values. The polar plots of vertically polarized HRS signal as a function of the angle of polarization of the incoming incident light shows two lobes, indicating that excitation is predominantly dipolar in nature although the size of some GNPs are big enough to show a quadrupolar response. It is believed that the presence of sharp tips at the surface of these large sized GNPs is responsible for the observed dipolar response. This study shows that GNPs having sharp tips might be a better candidate when their nonlinear properties are used for sensing applications.

Formation of a gold–carbon dot nanocomposite with superior catalytic ability for the reduction of aromatic nitro groups in water

Probing on the synthesis of gold-carbon dot nanocomposite for catalytic reduction of aromatic nitrogroup.

Synthesis of Some New Isoxazoline Derivatives of Chalconised Indoline 2-one as a Potential Analgesic, Antibacterial and Anthelmimtic Agents

A series of novel 1[5”-(2”’-substituted phenyl)-4”,5”’-dihydro isoxazole-3”-yl]-3-[(4 substituted phenyl)imino]1-3-dihydro-2H-indole-2-one were synthesized from different substituted chalconised indole-2,3-dione was prepared from the different chalconised Isatin. The structures of the compounds were elucidated by elemental and spectral (IR, ¹H NMR, and MS) analysis. The synthesized compounds were screened for their analgesic activity by the acetic acid induced Writhing method and in vitro antimicrobial activity against the Gram-positive bacteria—Staphylococcus aureus and the Gram-negative bacteria—Pseudomonas auroginosa, Pseudomonas mirabilis, and E. coli by the cup plate agar diffusion method. Compounds 6a₁, 6a₃, 6b₃, and 6b₂ were found to be active against bacteria. The compounds 6a₁, 6b₃, and 6a₃ show a significant analgesic activity. Synthesized compounds also screened for anthelmintic activity against Pheretima posthuma. Compounds 6a₁, 6b₁, and 6b₃ show significant anthelmintic activity.

Hooch blindness: a community study report on a few indoor patients of toxic optic neuropathy following consumption of adulterated alcohol in West Bengal

INTRODUCTION

Hooch blindness following consumption of adulterated alcohol has been known for centuries.

OBJECTIVE

To study cases of mass alcohol intoxication followed by Hooch blindness in eastern India.

MATERIALS AND METHODS

Ten patients of toxic amblyopia collected from a community mass intoxication following consumption of adulterated alcohol were studied. The parameters studied were the findings of ocular examination, applanation tonometry, automated perimetry and visual-evoked potential (VEP). As a part of the special investigations fundus photography and OCT were done. Routine blood examination, fasting lipid profile, postprandial blood sugar estimation were done . All patients were treated with injections of methyl prednisolone and Hydroxy cobalamine, antioxidants and local neuro-protective agents.

RESULTS

Along with diminished vision (from NPL to 3/60), marked pallor of the disc without any other retinal change were noted. The amplitude on VEP was significantly reduced. However, visual improvement (up to 6/18) in 7 patients was observed within 6 weeks of treatment.

CONCLUSION

Hooch blindness in India can be prevented by creating awareness among the target population and reducing the cost of country liquor.

Synthesis and evaluation of 1,3 di-substituted schiff, mannich bases and spiro isatin derivatives

Schiff bases of isatin with aminothiazole, its N-mannich bases and Spiro isatin derivatives were synthesized. Their chemical structures were confirmed by Infrared, 1H-Nuclear Magnetic Resonance data and elemental analysis. Antimicrobial evaluation was performed by the agar diffusion method against four pathogenic bacteria and two pathogenic fungi. Anti-inflammatory activity was tested by carragenin-induced rat paw edema and compounds were evaluated for analgesic action by the acetic acid-induced writhing method; Compounds Aa, Ab and A5, A6 were found to be active against bacteria and fungi. The compounds A3, A6, Aa and Ab showed anti-inflammatory activity, having a percentage protection value of 34.69, 32.65, 38.77 and 36.73 as compared with that of indomethacin, with % protection of 46.93. Similarly, the compounds Aa, Ab and A6 showed analgesic activity, with % protection of 67.51, 64.78 and 49.81 as compared with the standard with % protection of 79.56.

A Recyclable Heterogeneous Copper(II) Schiff Base Catalyst for the O-Arylation Reaction of Phenols with Aryl Halides

Immobilisation of copper acetate onto a modified polystyrene provided a polymer-supported copper(II) Schiff base catalyst, which is effective in the O-arylation reaction of phenols with aryl halides to give diaryl ethers in high yields. This catalyst is air-stable and was recycled for five times with minimal loss of activity.

An efficient and reusable polymer-supported palladium catalyst for the Suzuki cross-coupling reactions of aryl halides

A reusable, air-stable polymer-anchored palladium (II) Schiff base complex catalyst, P-[{(NCH)C6H4}Pd(OAc)]2 was prepared and was found to be highly active in Suzuki cross-coupling reactions of aryl halides with phenyl boronic acid in an aqueous medium to give biaryl products in high yields.

Treatment of arsenic contaminated water in a laboratory scale up-flow bio-column reactor

The present paper describes the observations on the treatment of arsenic contaminated synthetic industrial effluent in a bio-column reactor. Ralstonia eutropha MTCC 2487 has been immobilized on the granular activated carbon (GAC) bed in the column reactor. The synthetic water sample containing As(T) (As(III):As(V)=1:1), Fe, Mn, Cu and Zn at the initial concentrations of 25, 10, 2, 5, 10 ppm, respectively, was used. Concentrations of all the elements have been found to be reduced below their permissible limits in the treated water. The significant effect of empty bed contact time (EBCT) and bed height on the arsenic removal was observed in the initial stage. However, after some time of operation (approximately 3-4 days) no such effect was observed. Removal of As(III) and As(V) was almost similar after approximately 2 days of operation. However, at the initial stage As(V) removal was slightly more than that of As(III). In absence of washing, after approximately 4-5 days of operation, the bio-column reactor was observed to act as a GAC column reactor based on physico-chemical adsorption. Like arsenic, the percent removals of Fe, Mn, Cu and Zn also attained minimum after approximately 1 day and increased significantly to the optimum value within 3-4 days of operation. Dissolved oxygen (DO) has been found to decrease along with the increasing bed height from the bottom. The pH of the solution in the reactor has increased slightly and oxidation-reduction potential (ORP) has decreased with the time of operation.

Treatment of arsenic contaminated water in a batch reactor by using Ralstonia eutropha MTCC 2487 and granular activated carbon

This paper presents the observations on the bio-removal of arsenic from contaminated water by using Ralstonia eutropha MTCC 2487 and activated carbon in a batch reactor. The effects of agitation time, pH, type of granular activated carbon (GAC) and initial arsenic concentration (As(o)) on the % removal of arsenic have been discussed. Under the experimental conditions, optimum removal was obtained at the pH of 6-7 with agitation time of 100 h. The % removal of As(T) increased initially with the increase in As(o) and after attaining the maximum removal (~86%) at the As(o) value of around 15 ppm, it started to decrease. Simultaneous adsorption bioaccumulation (SABA) was observed, when fresh GAC was used as supporting media for bacterial immobilization. In case of SABA, the % removal of As(III) was almost similar (only ~1% more) to the additive values of individual removal of As(III) obtained by only adsorption and only bio-adsorption. However, for As(V) the % removal was less (~8%) than the additive value of the individual % removals obtained by only adsorption and bio-adsorption. Percentage removal of Fe, Mn, Cu and Zn were 65.17%, 72.76%, 98.6% and 99.31%, respectively. Maximum regeneration (~99.4%) of the used bio-adsorbent was achieved by the treatment with 5NH(2)SO(4) followed by 1N NaOH and 30% H(2)O(2) in HNO(3). The fitness of the isotherms to predict the specific uptake for bio-adsorption/accumulation process has been found to decrease in the following order: Temkin isotherm>Langmuir isotherm>Freundlich isotherm. For the adsorption process with fresh GAC the corresponding order is Freundlich isotherm>Langmuir isotherm>Temkin isotherm for As(V) and As(T). However, for As(III) it was Langmuir>Temkin>Freundlich.

Effects of adsorbent dose, its particle size and initial arsenic concentration on the removal of arsenic, iron and manganese from simulated ground water by Fe3+ impregnated activated carbon

This paper presents the observations of the study on arsenic removal from a contaminated ground water (simulated) by adsorption onto Fe(3+) impregnated granular activated carbon (GAC-Fe). Fe(2+), Fe(3+) and Mn(2+) have also been considered along with arsenic species in the water sample. Similar study has also been done with untreated granular activated carbon (GAC) for comparison. The effects of adsorbent dose, particle size of adsorbent and initial arsenic concentration on the removal of As(T), As(III), As(V), Fe(2+), Fe(3+) and Mn(2+) have been discussed. Under the experimental conditions, the optimum adsorbent doses for GAC-Fe and GAC have been found to be 8 g/l and 24 g/l, respectively with an agitation time of 15 h. Particle size of the adsorbents (both GAC and GAC-Fe) has shown negligible effect on the removal of arsenic and Fe species. However, for Mn removal the effect of adsorbent particle size is comparatively more. Percentage removal of As(T), As(V) and As(III) increase with the decrease in initial arsenic concentration (As(0)). However, the increase in percentage removal of all the arsenic species with decrease in As(0) are less for higher value of As(0) (3000-500 ppb) than those of the lower value of As(0) (500-10 ppb). The % removal of As(T), As(III), As(V), Fe, and Mn were approximately 95%, 92.4%, 97.6%, 99% and 41.2%, respectively when 8 g/l GAC-Fe was used at the As(0) value of 200 ppb. However, for GAC these values were approximately 55.5%, 44%, 71%, 98% and 97%. The pH and temperature of the study were 7+/-0.1 and 30+/-1 degrees C, respectively.

Laboratory based approaches for arsenic remediation from contaminated water: recent developments

Arsenic contamination in water has posed severe health problems around the world. In spite of the availability of some conventional techniques for arsenic removal from contaminated water, development of new laboratory based techniques along with enhancement and cost reduction of conventional techniques are essential for the benefit of common people. This paper provides an overview of the arsenic issue in water such as modes of contamination of ground water as well as surface water by arsenic, its metabolism and health impacts, factors influencing arsenic poisoning, fundamentals of arsenic poisoning mechanism and world scenario of arsenic poisoning. It discusses and compares the conventional laboratory based techniques, like precipitation with alum, iron, Fe/Mn, lime softening, reverse osmosis, electro dialysis, ion exchanges, adsorption on activated alumina/carbon, etc., for arsenic removal from contaminated water. It also discusses the best available techniques and mentions the cost comparison among these techniques too. Recent developments in the research on the laboratory based arsenic removal techniques, like improvement of conventional techniques and advances in removal technology along with its scopes and limitations have also been reviewed.

The newer unconventional indications of permanent pacemakers

In recent years, the indications for permanent pacemakers have expanded. The interest has focussed on hypertrophic cardiomyopathy, dilated cardiomyopathy and a new entity called hypertensive hypertrophy with cavity obliteration (HHCO). Pacemaker therapy is establishing itself for the prevention of atrial fibrillation. Pacing for neurocardiogenic syncope with newer pacing mode has encouraging datas. Pacemaker for long QT syndrome, after cardiac transplant and for haemodynamic improvement in occasional cases of first degree atrio-ventricular block is getting attention. The AHA and ACC guidelines updated in 1998 for implantation of cardiac pacemakers, now include several of these newer indications.