The level of tungstate in freshwater is disturbing due to its toxicity and its impact to human health. Thus, the current study explores the use of Ag nanoparticle (AgNP)–treated activated carbon ...(AgNPs/AC) nanocomposite as solid phase extractor (SPE) for removal of trace levels of tungstate ions in water. The AgNPs/AC was synthesized by chemical binding of Ag nanoparticles onto AC. The microstructure image indicated that the AgNPs were uniformly dispersed on AC surface and thus maintaining high surface area. Scanning electron micrographs of AgNPs/AC revealed a three-dimensional structure which is suitable as SPE. The AgNPs/AC nanocomposite was used as a low-cost and effective SPE for tungstate removal from water. Adsorption of tungstate from aqueous media reached maximum at pH ≈ 4 and reached equilibrium in < 20 min. Tungstate sorption followed pseudo-second-order kinetic with an overall rate constant (
k
) of 0.72 min.
−1
The negative values of Δ
H
and Δ
G
are interpreted as exothermic and spontaneous reaction of tungstate sorption by the adsorbent, respectively. The positive value of Δ
S
(
R
2
= 0.999) reflected good absorption and/or adsorption of the oxyanion WO
4
2−
as an ion associate with the bulky cations and the surface area available in the nanocomposite. The sorbent AgNPs/AC was also packed column for preconcentration of trace levels of tungstate in tap water samples. Tungstate species were satisfactorily recovered with NaOH (1.0 mol L
−1
) and subsequently ICP-OES analyzed.
The physics laboratory has long been a distinctive feature of physics education. It has been given a central role in the teaching and learning of physics at school and undergraduate levels in ...universities. The literature indicates that science educators have suggested that there are academically rich benefits in the learning and understanding of physics based on laboratory work. However, some educators have begun to raise serious and valid questions about the effectiveness of the learning through laboratory work in science subjects and the heavy cost for the establishment and maintenance of laboratories. This research paper provides perspectives on these issues through a brief review of the history, goals and objectives related to the physics undergraduate laboratory. An empirical research study was conducted to determine the university students' perceptions, views and opinions with regard to physics learning during undergraduate laboratory work. This involved 143 students from first and higher years and the evidence was gathered by survey and focus group interviews, the former using a variety of types of questions. The evidence from the students is positive and suggests that undergraduate physics laboratory work may well be contributing towards the achievement of specific desirable goals. (Contains 8 tables.)
The present study was conducted to test the possible teratogenic and toxic effects of anti-cancer drug heptaplatin (SKI 2053) on developing embryos and fetuses in gestating SWR/J mice. Dose levels of ...5.0, 10.0 and 12.5 mg heptaplatin/kg b.wt. were intraperitoneally administered to pregnant mice on days 6-8, 9-11 and 12-14 of gestation. On day 17 of gestation, all fetuses were removed and examined for toxic phenomena (embryo-fetal toxicity) by taking observation on live fetuses and embryonic resorption. Fetuses were also examined for external, internal and skeletal malformations. None of the dams treated with heptaplatin at any of the dose levels used in the present study died during the experimental period. Higher doses of heptaplatin caused greater embryonic resorption and reduced number of live fetuses. However, no loss of body weight was noticed in fetuses at any of the dose levels administered. At highest dose of heptaplatin (12.5 mg kg(-1)), tail deformity was observed in the form of short and curve tails whereas no other anatomical or skeletal malformations were noticed in any of the fetuses. In addition to mild embryo-fetotoxicity, the study indicates mild teratogenic effects of hetaplatin as reflected in fetal abnormalities at low frequency. These results have significant implications for protracted use of this drug.
Objective: To green synthesize and characterize copper nanoparticles (CuNPs) using Astragalus sinicus, as well as evaluate the acaricidal, larvacidal, and repellent activities of CuNPs against ...Hyalomma anatolicum (H. anatolicum), one of the most prevalent ticks infesting cattle in Saudi Arabia. Methods: CuNPs were green synthesized by adding the Astragalus sinicus extract to a copper sulfate solution. The acaricidal, larvicidal, and repellent activities of CuNPs against H. anatolicum were assessed via the adult immersion test, the larval packet test, and the vertical movement behavior of tick larvae, respectively. The effects of CuNPs on acetylcholinesterase as well as oxidative enzyme activities were examined. Results: The green synthesized CuNPs displayed a spherical form with a size range of 15-75 nm. After exposure of adult H. anatolicum to different concentrations of CuNPs, the viability rate of adult H. anatolicum and the mean number, weight, and hatchability of eggs were noticeably reduced, in comparison to the control group (P<0.001). In addition, the viability rate of larvae considerably declined (P<0.001) with the LC50 and LC90 values of 11.30 and 20.34 μg/mL, respectively. The maximum repellent activity of CuNPs was observed at 50, 100, and 200 μg/mL with complete repellent activity after 60, 120, and 180 min of exposure, respectively. CuNPs, mainly at ½LC50 and LC50 concentrations, markedly suppressed the acetylcholinesterase activity of the larval stage of H. anatolicum (P<0.001). Moreover, CuNPs, mainly at LC50 dose, significantly elevated malondialdehyde level while declining glutathione-S-transferase level in H. anatolicum larvae (P<0.001). Conclusions: CuNPs show potent acaricidal, larvicidal, and repellent activities against adults and larvae of H. anatolicum. However, further studies must be performed to clarify the precise mechanisms and the efficacy of CuNPs in practical use.
In this research, cell-free extracts from magnesite mine-isolated actinobacterial strain (M10A62) were used to produce silver sulfide nanoparticles (Ag
SNPs).
JX905302, actinobacteria capable of ...producing Ag
SNPs, was used to synthesize Ag
NPs. The UV–vis range was used to confirm the biosynthesized Ag
NPs; Fourier transform infrared spectroscopy (FT-IR), atomic force microscopy (AFM), transmission electron microscopy (TEM), X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDAX), and dynamic light scattering analysis were employed to characterize them further. Surface resonance plasma (SRP) for Ag
SNPs was obtained at 355 nm using UV–visible spectroscopy; FT-IR detected bimolecular and eventually microbial-reduced Ag
SNPs from
culture extract. Furthermore, AFM and TEM analysis confirms that the synthesized Ag
SNPs were spherical in shape. Dynamic light scattering revealed a negatively charged Ag
NPs surface with a diameter of 10 nm. The XRD spectrum showed the crystalline nature of the obtained particles. EDAX revealed a pure crystalline nature, and a significant silver particle signal confirms the presence of metallic silver and sulfide nanoparticles together with the signals of Cu and C atoms. After 40 and 48 h of treatment at 150–200 µg·ml
, Ag
SNPs produced the highest mortality in
,
, and
larvae. Hence, the biosynthesized Ag
SNPs may be useful for potential pest control in integrated pest management and vector control program as a safer, cost-effective, selective, and environmentally friendly approaches.
Ixodid ticks are hematophagous obligatory ectoparasites that occur worldwide and transmit pathogens to humans and other vertebrates, causing economic livestock losses. The Arabian camel (Camelus ...dromedarius Linnaeus, 1758) is an important livestock animal in Saudi Arabia that is vulnerable to parasitism by ticks. The diversity and intensity of ticks on Arabian camels in certain localities in the Medina and Qassim regions of Saudi Arabia were determined. One hundred forty camels were examined for ticks, and 106 were infested (98 females, 8 males). A total of 452 ixodid ticks (267 males, 185 females) were collected from the infested Arabian camels. The tick infestation prevalence was 83.1% and 36.4% in female and male camels, respectively (female camels harbored significantly more ticks than did male camels). The recorded tick species were Hyalomma dromedarii Koch, 1844 (84.5%); Hyalomma truncatum Koch, 1844 (11.1%); Hyalomma impeltatum Schulze and Schlottke, 1929 (4.2%); and Hyalomma scupense Schulze, 1919 (0.22%). Hyalomma dromedarii was the predominant tick species in most regions, with a mean intensity of 2.15 ± 0.29 ticks/camel (2.5 ± 0.53 male ticks/camel, 1.8 ± 0.21 female ticks/camel). The proportion of male ticks was higher than that of female ticks (59.1 vs. 40.9%). To the best of our knowledge, this is the first survey of ixodid ticks on Arabian camels in Medina and Qassim, Saudi Arabia.
Fifty strains of different microorganisms with ability to degrade chitin were isolated during a screening program. One of the most potent isolates (strain JK1) was identified as Aeromonas sp. and was ...deposited in Persian Type Culture Collection (PTCC 1691). Identification was carried out using morphological and biochemical properties along with 16S rRNA partial sequence analysis. This strain was able to produce high levels of extracellular chitinase in media containing chitin as sole carbon source. The effects of medium composition and physical parameters on chitinase production by this organism were studied. The optimized medium was found to contain colloidal chitin 0.75% (w/v), ammonium sulfate 0.15% (w/v), magnesium chloride 7.5 mM and Triton X-100 0.2% (v/v). The highest enzyme production by Aeromonas sp. JK1 was obtained at pH 8,30 degree C and after 48 h growth. With respect to high amount of chitinase production by this strain in a simple medium and the relatively short time, this strain could be a suitable candidate for production of chitinase on an industrial scale and merits further investigation into its structure and characteristics.
Visible light communications (VLC) is gaining interest as one of the enablers of short-distance, high-data-rate applications, in future beyond 5G networks. Moreover, non-orthogonal multiple-access ...(NOMA)-enabled schemes have recently emerged as a promising multiple-access scheme for these networks that would allow realization of the target spectral efficiency and user fairness requirements. The integration of NOMA in the widely adopted orthogonal frequency-division multiplexing (OFDM)-based VLC networks would require an optimal resource allocation for the pair or the cluster of users sharing the same subcarrier(s). In this paper, the max-min rate of a multi-cell indoor centralized VLC network is maximized through optimizing user pairing, subcarrier allocation, and power allocation. The joint complex optimization problem is tackled using a low-complexity solution. At first, the user pairing is assumed to follow the divide-and-next-largest-difference user-pairing algorithm (D-NLUPA) that can ensure fairness among the different clusters. Then, subcarrier allocation and power allocation are solved iteratively through both the Simulated Annealing (SA) meta-heuristic algorithm and the bisection method. The obtained results quantify the achievable max-min user rates for the different relevant variants of NOMA-enabled schemes and shed new light on both the performance and design of multi-user multi-carrier NOMA-enabled centralized VLC networks.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
This study focused on testing manufactured silver nanoparticles (AgNPs) against the malaria pathogen
and the malaria vector
using the plant filtrate from
. The
leaf extracts were used to synthesize ...the AgNPs, which were then subjected to several physicochemical methods to determine their characteristics. To evaluate the effectiveness of the green produced AgNP therapy, the mosquitocidal activity of
, cytotoxicity assay in Vero cells, and antiplasmodial activity assay were performed. The larval and pupal toxicity of biosynthesized AgNPs against the malarial vector
is 90% promising in laboratory settings at low dosages (10 ppm). When tested on African green monkey kidney cells, the cytotoxic effect of biosynthesized materials was found to be inappropriately damaging up to 100 g·mL
. The antimalarial efficacy of AgNPs was evaluated against
strains. The parasites that were restrained by AgNPs at 100 ppm had the highest parasitemia restraint rate (80.4%). AgNPs then showed significant
antimalarial activity against
. Our findings suggested that the biosynthesized AgNPs might function as a novel antimalarial agent that is both safer for the environment and a barrier to infections spread by mosquitoes.
Illustration of AgNP synthesis in the fight against malaria.
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