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"Isa, M"
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Heavy metal transport with adsorption for instantaneous and exponential attenuation of concentration
2024
Heavy metal pollutant is a serious problem in environmental pollution, and it is very difficult to eradicate once it enters the soil. As heavy metal adsorption has been proven to occur, the heavy metal’s behaviour can be modeled as a transport equation with adsorption. Previous adsorption term mostly due to the concentration alone, while in here, the desorption effect given by the rate of change of the concentration is also included. Also, the heavy metals are frequently considered to enter the soil after being dumped into the soil for a certain period of time. But, quick dumping onto the soil can introduce heavy metal instantaneously. Heavy metals entering the soil through leaching or when their concentration in the soil is influenced by chemical reactions, can all lead to the exponential decay of heavy metals entering the soil. Based on two-dimensional advection diffusion equation (ADE) with the new adsorption term, analytical solutions are obtained for the cases of instantaneous and exponential attenuation of heavy metals emission to soil by the method of Laplace transform. The results highlight the significant influence of emission type on the peak concentrations. If heavy metals are instantaneously enter the soil, the peak occurs in the range of 1–3 m radius from the point of emission on the first day, while for exponential attenuation the peak occurs close to the point of emission. Furthermore, there exists a correlation between retardation factors and heavy metal concentrations, where a decrease in retardation factors leads to an increase in heavy metal concentration. It is essential to investigate both types of heavy metals emission to provide valuable information for proper pollution management, effective environmental regulations and enforcement.
Journal Article
Novel Proton Conducting Solid Bio-polymer Electrolytes Based on Carboxymethyl Cellulose Doped with Oleic Acid and Plasticized with Glycerol
2016
The plasticized solid bio-polymer electrolytes (SBEs) system has been formed by introducing glycerol (Gly) as the plasticizer into the carboxymethyl cellulose (CMC) doped with oleic acid (OA) via solution casting techniques. The ionic conductivity of the plasticized SBEs has been studied using Electrical Impedance Spectroscopy. The highest conductivity achieved is 1.64 × 10
−4
S cm
−1
for system containing 40 wt. % of glycerol. FTIR deconvolution technique had shown that the conductivity of CMC-OA-Gly SBEs is primarily influenced by the number density of mobile ions. Transference number measurement has shown that the cation diffusion coefficient and ionic mobility is higher than anion which proved the plasticized polymer system is a proton conductor.
Journal Article
Enhancing thermo-mechanical properties of Honckenya fiber-reinforced polypropylene composites: a comparative study of novel potash salt and NaOH treatments
2026
Focus is gradually shifting from complete reliance on chemical-based treatment, toward eco-friendly alternatives for natural fiber treatment in composite development. This study introduces, for the first time, natural potash salt (KTN) as a multicomponent, sustainable treatment for natural fibers. The thermo-mechanical behavior of Honckenya fiber-reinforced polypropylene composites (HFRPPCs) treated with potash, NaOH, and untreated fibers was investigated using differential thermal analysis (DTA) and dynamic mechanical analysis (DMA). Fiber characterization was performed via FTIR and SEM. Results indicate that treated composites exhibited significantly enhanced properties. Potash-treated HFRPPC demonstrated superior performance with the highest storage modulus (1431.79 MPa), loss modulus (129.57 MPa), and tanδ (0.16). DTA and DMA analyses confirm that potash treatment yields better thermo-mechanical properties than NaOH treatment, offering an eco-friendly alternative for enhancing thermal stability and expanding service temperature ranges in sustainable automotive, interior, and construction materials.
Journal Article
Global meta-analysis shows action is needed to halt genetic diversity loss
2025
Mitigating loss of genetic diversity is a major global biodiversity challenge
1
,
2
,
3
–
4
. To meet recent international commitments to maintain genetic diversity within species
5
,
6
, we need to understand relationships between threats, conservation management and genetic diversity change. Here we conduct a global analysis of genetic diversity change via meta-analysis of all available temporal measures of genetic diversity from more than three decades of research. We show that within-population genetic diversity is being lost over timescales likely to have been impacted by human activities, and that some conservation actions may mitigate this loss. Our dataset includes 628 species (animals, plants, fungi and chromists) across all terrestrial and most marine realms on Earth. Threats impacted two-thirds of the populations that we analysed, and less than half of the populations analysed received conservation management. Genetic diversity loss occurs globally and is a realistic prediction for many species, especially birds and mammals, in the face of threats such as land use change, disease, abiotic natural phenomena and harvesting or harassment. Conservation strategies designed to improve environmental conditions, increase population growth rates and introduce new individuals (for example, restoring connectivity or performing translocations) may maintain or even increase genetic diversity. Our findings underscore the urgent need for active, genetically informed conservation interventions to halt genetic diversity loss.
A comprehensive meta-analysis of global terrestrial and marine genetic diversity covering more than three decades of research demonstrates rapid loss of genetic diversity and identifies conservation interventions that could mitigate this process.
Journal Article
Proton-Conducting Biopolymer Electrolytes Based on Carboxymethyl Cellulose Doped with Ammonium Formate
2022
In this work, CMC-AFT biopolymer electrolytes system was developed using Carboxymethyl cellulose (CMC) doped with varied amount (10–50 wt.%) of ammonium formate (AFT) in order to study the effect of AFT on the biopolymer-salt system. The chemical structure of the biopolymer was studied using Fourier-Transform infrared (FTIR) and X-ray diffraction (XRD). The interaction between the COO− of CMC and the weakly-bound H+ of NH4+ AFT occurred at 1573 cm−1 as seen in FTIR analysis and the amorphous phase was found to increase with the addition of AFT as seen from XRD pattern. Both FTIR and XRD testing indicates that the AFT had disrupted the CMC crystalline structure. The ionic conductivity of the CMC-AFT biopolymer electrolytes increases and achieved the highest value of 1.47 × 10−4 S·cm−1 with the addition of AFT. The impedance measurement showed that the capacitive and resistive behavior inside the biopolymer diminished when 50 wt.% of AFT was added. Dielectric analysis confirmed the increased number of charge carriers is due to the increase in AFT composition. Further dielectric analysis showed the occurrence of conductivity relaxation peak thus affirmed the charge carriers’ ability to travel further to a longer distances when AFT composition increases from 10 to 50 wt.%. The dielectric properties confirmed the non-Debye behavior of the CMC-AFT biopolymer electrolytes.
Journal Article
Living in a post-industrial landscape
by
Bruford, Michael W.
,
King, R. Andrew
,
Osmond, Daniel R.
in
Adaptation
,
Aquatic ecosystems
,
Barriers
2024
Aim The British Isles have been worked for millennia to extract metal ores to feed industrial development, leaving a legacy of mine water pollution that continues to impact freshwater communities in many regions. Brown trout (Salmo trutta L.) have long been observed to persist in these metal‐impacted systems as apex predators, with previous studies showing a small number of impacted populations to be highly genetically divergent. We sought to understand the scale of genetic diversity across regions and the repeatability of genetic divergence in trout populations affected by metal pollution. Location We examined four mine water‐impacted regions across the British Isles: west Wales, northeast England, southwest England and southeast Ireland. Methods We employed a panel of 95 SNP loci to screen 1236 individuals from 71 sites representing paired metal‐impacted and clean sites from across the four regions. From these, we obtained diversity statistics, assessed genetic structuring of populations and modelled historical demographic scenarios to understand which factors most credibly explain genetic variation in divergent populations. Results We evidenced hierarchical population structure in the regions studied, in line with expectations from phylogeographic history. However, in a hierarchical analysis of genetic structuring the first level of differentiation was driven by the divergence of the metal‐impacted trout of Cornwall in southwest England. Within regions we observed reduced genetic diversity and repeated patterns of local genetic sub‐structuring between paired samples from metal‐impacted and relatively clean sites. Demographic history analyses suggested the timing of these splits to be relatively recent and to be associated with periods of peak mining activity. Main conclusions Our findings demonstrate distinct patterns of genetic isolation and reduced diversity arising from legacy pollution in freshwater ecosystems, with impacts being most apparent where both chemical pollution and physical barriers are present. Management should focus on the amelioration of mine water wash‐out and the removal of barriers to fish movement to safeguard genetic diversity in impacted populations.
Journal Article
Prevalence, capsular types, antimicrobial resistance and risk factors associated with pneumococcal carriage among children after long-term 10-valent pneumococcal conjugate vaccine use in Brazil
by
Cardoso-Marques, Nayara T.
,
Antunes, Isa M.F.
,
Cabral, Amanda S.
in
Allergy and Immunology
,
Anti-Bacterial Agents - pharmacology
,
Anti-Bacterial Agents - therapeutic use
2023
The 10-valent pneumococcal conjugate vaccine (PCV10) was introduced for childhood vaccination in Brazil’s National Immunization Program in 2010. After nine years of PCV10 use, we investigated the carriage prevalence, capsular types, antimicrobial resistance and risk factors among children living in Niterói city, RJ, Brazil.
Between September and December 2019, we conducted a cross-sectional study and recruited children under 6 years of age. Antimicrobial susceptibility was evaluated by the disk-diffusion method and MICs to beta-lactams and macrolides were determined by E-test®. Capsular types were deduced by multiplex PCR. Logistic regression was used to predict risk factors for pneumococcal carriage.
Seventy-five (17.4%) of the 430 children were pneumococcal carriers. The most frequent capsular types were 6C/D (14.7%), 11A/D (13.3%), and 23B (9.3%). PCV10 serotypes represented 5.3%. All isolates were susceptible to levofloxacin, linezolid, rifampicin, and vancomycin. Penicillin non-susceptible pneumococci (PNSP) made up 37.3%, with penicillin and ceftriaxone MICs ranging from 0.12 to 4.0 μg/ml and 0.064–4.0 μg/ml, respectively. Of the 19 (25.3%) erythromycin-resistant (ERY-R) isolates (macrolide MICs of 6 to >256 μg/ml), most had the cMLSB phenotype (84.2%) and carried the erm(B) gene (73.7%). We detected 17 (22.6%) multidrug-resistant (MDR) isolates, strongly associated with serotype 6C/D. Presence of any symptoms, chronic diseases, childcare center attendance, living with young siblings, slum residence, and unstable income were predictors of pneumococcal carriage.
Long-term universal childhood use of PCV10 has nearly eliminated carriage with PCV10 serotypes, but the high frequency of MDR isolates, especially associated with serotype 6C/D, remains a concern. Replacing PCV10 with PCV13 should reduce the proportion of ERY-R isolates and PNSP by at least 14% and 18%, respectively.
Journal Article
Synthesis and physicochemical characterization of organomodified halloysite/epoxidized natural rubber nanocomposites: a potential flame-resistant adhesive
by
Salehabadi, A
,
Abu Bakar, M
,
Abu Bakar, N. H. H
in
Analysis
,
Characterization and Evaluation of Materials
,
Chemical properties
2016
The physicochemical properties of organomodified halloysite nanotubes (OHNT)/epoxidized natural rubber with 50 % epoxidation level (ENR-50) were subjected for evaluation in this study. Several OHNT/ENR-50 nanocomposites with different weight ratios of OHNT to ENR-50 were prepared via solvent casting technique. The influence of OHNT on the physicochemical profile of the nanocomposites was elucidated via thermal, morphological, and nanoindentation characterizations. Both XRD and FTIR analyses suggested that the ENR-50 was mainly absorbed onto the surface of HNT via hydrogen bonding. SEM analyses revealed complete homogenous dispersion of OHNTs in the presence of ENR-50. The thermal decomposition profiles of the nanocomposites indicated an improvement in the maximum decomposition temperature (T ₘₐₓ) upon increasing the OHNT content. The mechanical aspect of the nanocomposites showed that the hardness (H) and reduce modulus (E ᵣ) of ENR-50 were also increased with incorporation of OHNT. Limited oxygen index test reveals that the prepared OHNT/ENR-50 nanocomposites are classified as self-extinguish materials. The OHNT/ENR-50 nanocomposites hold potential application in flame-resistant coatings.
Journal Article
Hybrids Along a Natural‐Anthropogenic Gradient: Improving Policy and Management Across All Levels of Biodiversity
by
Bruford, Michael W.
,
Hoban, Sean
,
Bishop von Wettberg, Eric
in
Adaptation
,
Biodiversity
,
Breeding
2025
Hybridization has long been a central topic in evolution and conservation. Recent developments in genomics have increased the ability to detect hybridization, defined here as breeding between species, subspecies or distinct populations, and assess levels of introgression between taxa. For decades, hybrids directly or indirectly created and/or spread by humans have typically been considered as threats to conservation, reflected by current regional and national environmental policies that focus largely on potential negative effects. In the context of the latest global conservation policy goals, and increasing evidence of historic natural hybridization events, we call for science‐based, reflective and context‐dependent management of hybrids, applying a framework that shifts focus towards measuring the impact of hybrids, and assessing potential risks and benefits. Alongside demographic and ecological information, it is crucial for impact assessments to consider genetic information, and conservation management of hybrids needs to be more case‐specific.
Journal Article
Walking in a heterogeneous landscape: Dispersal, gene flow and conservation implications for the giant panda in the Qinling Mountains
by
Bruford, Michael W.
,
Hu, Yibo
,
Russo, Isa‐Rita M.
in
Animal behavior
,
Data processing
,
Demography
2018
Understanding the interaction between life history, demography and population genetics in threatened species is critical for the conservations of viable populations. In the context of habitat loss and fragmentation, identifying the factors that underpin the structuring of genetic variation within populations can allow conservationists to evaluate habitat quality and connectivity and help to design dispersal corridors effectively. In this study, we carried out a detailed, fine‐scale landscape genetic investigation of a giant panda population from the Qinling Mountains for the first time. With a large microsatellite data set and complementary analysis methods, we examined the role of isolation‐by‐barriers (IBB), isolation‐by‐distance (IBD) and isolation‐by‐resistance (IBR) in shaping the pattern of genetic variation in this giant panda population. We found that the Qinling population comprises one continuous genetic cluster, and among the landscape hypotheses tested, gene flow was found to be correlated with resistance gradients for two topographic factors, slope aspect and topographic complexity, rather than geographical distance or barriers. Gene flow was inferred to be facilitated by easterly slope aspect and to be constrained by topographically complex landscapes. These factors are related to benign microclimatic conditions for both the pandas and the food resources they rely on and more accessible topographic conditions for movement, respectively. We identified optimal corridors based on these results, aiming to promote gene flow between human‐induced habitat fragments. These findings provide insight into the permeability and affinities of giant panda habitats and offer important reference for the conservation of the giant panda and its habitat.
Journal Article