Sulfur deficiency mediated visible emission of ZnS QDs by magnesium dopant and their application in waste water treatment

The photocatalyst with antimicrobial activity serves as a better candidate material for wastewater treatment, as wastewater contains microbes, hazardous dyes, and heavy metals. Hence, the present study extensively examines the photocatalytic and antibacterial activities against two waterborne bacterial strains, namely Salmonella typhi and Escherichia coli. Pure and Mg-doped ZnS (Mg:ZnS) quantum dots (QDs) were synthesized using a low-cost and simple co-precipitation method. The QDs' structural, surface morphology, chemical purity, and optical characteristics were analyzed through XRD, SEM, EDAX, TEM, UV-visible, and photoluminescence spectra. The incorporation of Mg dopants did not introduce significant alterations to the cubic blende structure of ZnS, nor did it induce substantial changes in the structural parameters. However, the QDs exhibited a slight sulfur deficiency, which was further increased by the presence of Mg dopant. The Mg dopant, due to its dominant compositional effect, reduced the band gap. Several optical emission bands were observed in the UV, violet, blue, and green regions, corresponding to NBE emission, sulfur-related defects, and Zn-related defects. Initially, Mg doping enhanced visible emission related to defects, while NBE emission was suppressed by the Mg dopant. However, increasing the concentration of the Mg dopant led to a slight increase in NBE emission. The Mg dopant enhanced the photocatalytic activity of the QDs, and a strong correlation was found between photocatalytic activity and NBE emission. The presence of the Mg dopant led to an increased rate of ROS-based decolorization by reducing the electron-hole recombination rate.

Greater efficiency of polyherbal drug encapsulated biosynthesized chitosan nano-biopolymer on diabetes and its complications

Diabetes is a highly complex disease that has an adverse impact on the lives of individuals, and the current medicines used to manage diabetes have obvious side effects. Medicinal plants, on the other hand, may serve as an alternate source of anti-diabetic drugs. A polyherbal combination has a higher and more extensive therapeutic potential than a single herb. Yet, due to deterioration during the absorption process, the usage of this drug still yields inadequate results. Encapsulation of polyherbal drug with chitosan nanoparticles is one of the key ways to solve this problem due to its biocombatibilty, slow and targeted drug delivery characteristics. In the present study, the chitosan was derived from prawn shell and the chitosan nanoparticles had been prepared by ionic-gelation method. The anti-diabetic polyherbal drug (Andrographis paniculata, Andrographis alata, Adhatoda zeylanica, Gymnema sylvestre, Syzygium cumini, and Justicia glabra) was encapsulated with a bio-derived chitosan biopolymer. The drug loading efficiency was about 85 %. The chemical and physical properties of the chitosan and drug-loaded chitosan nanoparticles had been analyzed by FT-IR absorption, XRD, SEM, TEM and EDAX analysis. The antidiabetic efficiency, hepatoprotective activity and antihyperlipedimic activity of the chitosan nanoparticles, polyherbal drug and polyherbal drug encapsulated with chitosan nanoparticles were assessed in a group of rats. The polyherbal drug reduced the serum glucose level from 306.4 mg/dL to 134.47 mg/dL, while the polyherbal drug encapsulated with chitosan nanoparticles reduced to 127.017 mg/dL. This was very close to the serum glucose level of non-diabetic rat (124.65 mg/dL). Further, it considerably increased the insulin level close to that of non-diabetic rat. Thus, the polyherbal drug encapsulated with chitosan nanoparticles showed superior efficiency in antidiabetic and also diabetic complications.

Weight-imposed Elite Hybrid Binary Cuckoo Search (EHBCS)-based clustering for improving network lifetime longevity

In Wireless Sensor Networks (WSNs), Clustering aids in maximizing the lifetime of the network with sustained energy stability in the sensor nodes during data dissemination. In this clustering process, the sensor nodes are organized into clusters with the potential fitness node designated as Cluster Heads (CHs) for collecting and forwarding the data to the sink. In specific, the energy consumption of sensor nodes during their role as CH is maximized with great impact over the network lifespan. In this paper, a Weight-imposed Elite Hybrid Binary Cuckoo Search (EHBCS)-based Clustering Mechanism is proposed for facilitating potent data transmission with minimized energy consumption and improved network lifetime. This EHBCS is proposed as a novel energy-sensitive CH selection framework based on the process of hierarchical routing through the inclusion of hybrid optimization algorithm. It selected CH depending on the parameters of Quality of Service (QoS), delay, distance, and energy into account. It integrated the merits of Binary Cuckoo Search and Elite Mechanism for selecting CHs and performing effective processes by preventing sinkhole issues in WSNs. The results of EHBCS confirmed better throughout by 11.32%, minimized energy consumption by 13.84%, and minimized delay by 16.12% with an increasing number of sensor nodes, compared to the baseline CH selection approaches used for exploration.

Molecular detection of Candidatus Rickettsia asembonensis in fleas collected from pets and domestic animals in Puducherry, India

Rickettsia are obligate intracellular pathogens transmitted by arthropod vectors. The re-emergence of several rickettsioses imposes severe global health burden. In addition to the well-established rickettsial pathogens, newer rickettsial species and their pathogenic potentials are being uncovered. There are many reports of spotted and typhus fever caused by rickettsiae in India. Hence, in this study we screened the ectoparasites of pet and domestic animals for the presence of rickettsia using polymerase chain reaction. Nine cat flea samples (Ctenocephalides felis felis), that tested positive for the presence of rickettsia were subjected to Multi Locus Sequence Typing. Nucleotide sequencing and Phylogenetic analysis of gltA, ompB and 16rrs genes revealed that the rickettsiae detected in cat fleas was Rickettsia asembonensis. Further studies are required to assess Rickettsia asembonensis pathogenic potential to human and its enzootic maintenance of in various hosts and vectors.

An assessment of human-elephant conflict and associated ecological and demographic factors in Nilambur, Western Ghats of Kerala, southern India

Elephant conservation carries cost in the form of human-elephant conflict and affects the wellbeing of people living near ecologically important areas.  Conflicts impart serious challenges towards the survival of Asian Elephants, which are categorized as Endangered in the IUCN Red List of Threatened Species.  Issues of wildlife conservation are least addressed in areas with less restricted categories of protection.  Hence an attempt was made to evaluate the intensity of elephant conflict and factors associated with its occurrence in villages with forest fringes of North and South Forest Divisions of Nilambur, Kerala, southern India.  It was hypothesized that variables such as number of houses, area of village, livestock population, forest frontage, and presence of water source along the forest boundary abutting the village to be the underlying correlates of conflict.  Field studies were conducted fortnightly from June 2014 to May 2015, by visiting farms and households of 17 selected forest fringe villages.  Observational methods, questionnaire surveys and secondary data collection were employed for this purpose.  A total of 277 incidents of crop depredation, 12 incidents of property damage, three human injuries, and one human death due to conflict were recorded during this period.  Crop raiding was highest during post monsoon season and it was low during pre-monsoon and monsoon seasons.  Multiple linear regression results suggest that forest frontage and livestock population were significant predictors of conflict incidence.  Information regarding the prime causes of conflict will be helpful for planning strategies for the establishment of appropriate mitigation methods.  The present study serves as baseline information which will be helpful for formulating prospective management plans.

Structural, optical, dielectric and antibacterial studies of Mn doped Zn0.96Cu0.04O nanoparticles

Zn(0.96-x)Cu0.04Mn(x)O (0⩽x⩽0.04) nanoparticles were synthesized by sol-gel method. The X-ray diffraction pattern indicated that doping of Mn and Cu did not change the ZnO hexagonal wurtzite structure. The Mn doped nanoparticles had smaller average crystallite size than un-doped Zn0.96Cu0.04O nanoparticles due to the distortion in the host ZnO lattice. This distortion prevented the subsequent growth and hence the size reduced by Mn doping. The changes in lattice parameters, average crystallite size, peak position and peak intensity confirmed the Mn substitution in Zn-Cu-O lattice. The Mn and Cu co-doping increased the charge carrier density in ZnO nanoparticles which led to increase the dielectric constant. The dielectric constant also varied by depend the size of the nanoparticles. The change in morphology by Mn-doping was studied by transmission electron microscope. The optical absorption and band gap were changed with respect to both compositional and size effects. The band gap was initially increased from 3.65 to 3.73 eV at 1% of Mn doping, while decreasing trend in band gap was noticed for further increase of Mn. The band gap was decreased from 3.73 to 3.48 eV when Mn concentration was increased from 2% to 4%. Presence of chemical bonding and purity of the nanoparticles were confirmed by FTIR spectra. The antibacterial study revealed that that the antibacterial activity of Zn0.96Cu0.04O is enhanced by Mn doping.

Hot topic: sonication increases the heat stability of whey proteins

The thickening or gelling of protein-based dairy streams and ingredients upon exposure to heat has been an ongoing problem in dairy processing for many decades. This phenomenon can restrict the range of dairy product options and reduce manufacturing efficiencies by limiting the type and extent of heat treatment that can be used. In this report, we outline a novel approach to overcoming this problem. The use of preheating treatments to induce whey protein aggregate formation in whey products is well known in the field. However, we show that the application of ultrasound for a very short duration after such a heating step breaks down these aggregates and prevents their reformation on subsequent heating, thereby reducing the viscosity increase that is usually associated with this process. This novel technique has the potential to provide significant economic benefit to the dairy manufacturing industry.

Minimising oil droplet size using ultrasonic emulsification

The efficient production of nanoemulsions, with oil droplet sizes of less than 100nm would facilitate the inclusion of oil soluble bio-active agents into a range of water based foods. Small droplet sizes lead to transparent emulsions so that product appearance is not altered by the addition of an oil phase. In this paper, we demonstrate that it is possible to create remarkably small transparent O/W nanoemulsions with average diameters as low as 40nm from sunflower oil. This is achieved using ultrasound or high shear homogenization and a surfactant/co-surfactant/oil system that is well optimised. The minimum droplet size of 40nm, was only obtained when both droplet deformability (surfactant design) and the applied shear (equipment geometry) were optimal. The time required to achieve the minimum droplet size was also clearly affected by the equipment configuration. Results at atmospheric pressure fitted an expected exponential relationship with the total energy density. However, we found that this relationship changes when an overpressure of up to 400kPa is applied to the sonication vessel, leading to more efficient emulsion production. Oil stability is unaffected by the sonication process.

Ultrasonic enhancement of the supercritical extraction from ginger

This work examines the concurrent use of power ultrasound during the extraction of pungent compounds from a typical herb (ginger) with supercritical CO(2). A power ultrasonic transducer with an operating frequency of 20 kHz is connected to an extraction vessel and the extraction of gingerols from freeze-dried ginger particles (4-8 mm) is monitored. In the presence of ultrasound, we find that both the extraction rate and the yield increase. The higher extraction rate is attributed to disruption of the cell structures and an increase in the accessibility of the solvent to the internal particle structure, which enhances the intra-particle diffusivity. While cavitation would readily account for such enhancement in ambient processes, the absence of phase boundaries should exclude such phenomena above the critical point. Possible alternate mechanisms for the cell structure damage are discussed.

Ultrasonic treatment of Cryptosporidium oocysts

The effect of 20 kHz ultrasound on the viability of Cryptosporidium oocysts was investigated. More than 90% of the dispersed Cryptosporidium oocysts could be deactivated in about 1.5 min of continuous sonication. In order to apply this technique to large quantities of contaminated water, quantitative filtration and redispersion of Cryptosporidium oocysts were investigated and found to be easily achievable. The estimated cost of sonication showed that the ultrasound treatment of Cryptosporidium oocysts contaminated water could be a very effective means of "deactivating" Cryptosporidium oocysts.

The effect of surface active solutes on bubbles exposed to ultrasound

A review of the effects of a range of surface active solutes, aliphatic alcohols, alkyl amines, carboxylic acids and surfactants on bubbles exposed to ultrasound is presented. The solutes are shown to affect the phenomenon of sonoluminescence (SL) in quite a number of different ways. Ionic surfactants have a strong influence on interbubble interactions which at low concentrations (1 mM) results in an enhancement in SL. Alcohols and the neutral forms of the organic acids and amines induce SL quenching. The SL quenching is attributed to the formation and accumulation of decomposition products in the hot core of an oscillating bubble resulting from the evaporation of volatile solute adsorbed at the bubble interface. Some results are presented on the influence of low concentrations of alcohol on the SL generated from a single bubble and on the bubble dynamics, when exposed to ultrasound. These results add support to the interpretation given for solute-induced effects observed in multibubble systems. It is also shown that SL can be used as an internal light source to excite aromatic solutes that subsequently fluoresce, a process referred to as sonophotoluminescence.

Multibubble sonoluminescence in aqueous salt solutions

The sonoluminescence from aqueous solutions containing various salts in the concentration range of 0 to 7 M has been examined using 3.5 ms pulses of 515 kHz ultrasound. In almost all cases the sonoluminescence intensity recorded increased with increasing salt level until a critical concentration (in the range of 1-2 M) was reached. At salt levels above the critical concentration the signal intensity decreased sharply with increasing salt concentration. It is not possible to satisfactorily account for the trends in terms of changes in solution viscosity, rate of bubble coalescence, water vapour pressure, air/water interfacial tension or ionic strength. However, a good correlation of the increase in the signal with the extent of gas solubilisation in the solutions with changing salt concentration was observed. Possible reasons for the signal increase with the addition of salts and the marked decrease at high salt concentrations are discussed.

Sonophotoluminescence from aqueous and non-aqueous solutions

The sonoluminescence generated in air-saturated aqueous and non-aqueous solutions using 515 kHz ultrasound has been used to vibronically excite several fluorescent solutes, namely fluorescein, eosin, pyranine and pyrene. Emission, referred to as 'sonophotoluminescence', was generated in situ with emission spectra that closely matched those obtained by direct photoexcitation of the solutes by an external light source. In the case of pyranine, experiments were also conducted in the presence of the surfactant, sodium dodecyl sulphate (SDS). The presence of 1 mM SDS enhances the sonoluminescence and sonophotoluminescence signals above that seen in pure water by a factor of about 2. Pyrene sonophotoluminescence was observed in ethylene glycol. The emission was quenched by the addition of I-, providing good evidence that emission was from pyrene in bulk solution and not within, or on the surface of cavitation bubbles.