The aim of this work was to assess the uptake of citrate-coated magnetite nanoparticles (NPs) by wheat plants and its effect on the bioaccumulation and toxicity of individual and joint Cd2+ and Cr6+ ...levels. Seven-day assays were conducted using quartz sand as the plant growth substrate. The endpoints measured were seed germination, root and shoot lengths, and heavy metal accumulation. Magnetite exhibited very low toxicity, regardless of the wheat seedling NP uptake and distribution into roots and shoots. The seed germination and shoot length were not sensitive enough, while the root length was a more sensitive toxicity endpoint. The root length of wheat seedlings exposed to individual metals decreased by 50% at 2.67mgCd2+kg−1 and 5.53mgCr6+kg−1. However, when magnetite NPs (1000mgkg−1) were added, the root length of the plants increased by 25 and 50%. Cd2+ and Cr6+ showed similar and noninteractive joint action, but strongly impaired the wheat seedlings. In contrast, an interactive infra-additive or antagonistic effect was observed upon adding magnetite NPs. Thus, cadmium and chromium accumulation in vegetable tissues was considerately diminished and the toxicity alleviated.
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•We assessed the effect of nanomagnetite on heavy metal toxicity in wheat plants.•Citrate-coated magnetite nanoparticles (NPs) exerted very low toxicity to plants.•Cadmium was more toxic than chromium and toxicity was mitigated by magnetite NPs.•Cadmium and chromium had a similar and noninteractive joint action on plants.•Metals showed an interactive infra-additive joint effect by adding magnetite NPs.
Cobalt ferrite nanoparticles (NPs) have received increasing attention due to their widespread therapeutic and agricultural applicability. In the environmental field, dry powder- and ...ferrofluid-suspended cobalt ferrite NPs were found to be useful for removing heavy metals and metalloids from water, while diluted suspensions of cobalt ferrite NP have been promisingly applied in medicine. However, the potential toxicological implications of widespread exposure are still unknown. Since cobalt ferrite NPs are considered residual wastes of environmental or medical applications, plants may serve as a point-of-entry for engineered nanomaterials as a result of consumption of these plants. Thus, the aim of this study was to assess the effects of dry powder and fresh cobalt ferrite NP on wheat plants. Seven-day assays were conducted, using quartz sand as the plant growth substrate. The toxicity end points measured were seed germination, root and shoot lengths, total cobalt (Co) and iron (Fe) accumulation, photosynthetic pigment production, protein (PRT) production, and activities of catalase (CAT), ascorbate peroxidase (APX), and guaiacol peroxidase (GPX). Increasing total Co and Fe in plant tissues indicated that wheat plants were exposed to cobalt ferrite NP. Seed germination and shoot length were not sufficiently sensitive toxicity end points. The effective concentration (EC
50
) that diminished root length of plants by 50% was 1963 mg/kg for fresh ferrite NPs and 5023 mg/kg for powder ferrite NP. Hence, fresh ferrite NPs were more toxic than powder NP. Plant stress was indicated by a significant decrease in photosynthetic pigments. CAT, APX, and GPX antioxidant enzymatic activity suggested the generation of reactive oxygen species and oxidative damage induced by cobalt ferrite NP. More studies are thus necessary to determine whether the benefits of using these NPs outweigh the risks.
Cost Model for CubeSat Projects in Mexico Jiménez Navarro, E N; Solís Santomé, A; Padilla Pérez, D A ...
Journal of physics. Conference series,
04/2023, Letnik:
2475, Številka:
1
Journal Article
Recenzirano
Odprti dostop
Abstract
This work focused on designing a cost estimation model in the area of space engineering for the development of nanosatellite projects in Mexico. See employed the use of methodologies such as ...Hall and Jenkins, software engineering cost estimating methodology, as well as project management methodology. Similarly, the COSYSMO methodology and parametric cost methodology were incorporated to guide this research towards the space sector. The estimation results are based on satellite engineering equations and forecasts of the inflation factor. Finally, a graphical user interface named SACANI was obtained. Allowing the estimating a nanosatellite project by ”integration of components” or by ”research and development”. The first asks the user for the components by subsystem through drop-down lists, giving a breakdown of the estimated costs for the CubeSat, development phases and ground station, according to the data provided by the interested party. The second model is more robust because it requests the type of project, the category, the amount of CubeSat required, the year to estimate the cost, the mass of the payload, among other data. Similarly, both models yield a previous result of the estimate made according to the data entered by the project estimator.
Phytoremediation is a technology for extracting or inactivating pollutants.
Echinochloa polystachya (H.B.K.) Hitchcock (Poaceae) is a fast-growing perennial grass that is common in tropical areas and ...is often found in oil-polluted soils that contain high concentrations of heavy metals. However, its tolerance to heavy metals, and its ability to accumulate them, has yet to be investigated. Here we test the hypothesis that
E. polystachya is able to accumulate high concentrations of cadmium (Cd). Plants were grown hydroponically with different levels of Cd
2+ (0, 0.25, 1, 2, 10, 50, and 100
mg
L
−1), and were found to be tolerant to Cd
2+ at all levels. No metal-toxicity symptoms were observed at any Cd
2+ level. Root and leaves Cd concentrations were 299
±
13.93 and 233
±
8.77
mg
kg
−1 (on a dry weight basis), respectively. Scanning electron microscopy showed the inclusion of Cd within the xylem; this result was confirmed by energy dispersive X-ray spectrometry. Leaf tissues also accumulated Cd, especially within the bulliform cells of the epidermis. We conclude that
E. polystachya is a hyperaccumulator of Cd. While data for other metals are not yet available,
E. polystachya shows promise in the phytoextraction of Cd from polluted tropical sites.
Echinoderms associated with coral communities in the Easter Pacific compose a conspicuous assemblage that alters their ecosystem structure and composition. The environmental conditions in the ...transitional region of Central Mexican Pacific (CMP) present high variability associated with climatic seasons and El Niño-Southern Oscillation (ENSO) events. In order to understand it, a research was held during four years (2011-2014) throughout the CMP region with seven conspicuous echinoderm indicator species. Echinoderms diversity, distribution, and density were measured, and also their relation with benthic coverage, depth, rugosity, and temperature. The echinoderm assemblages changed in density and diversity among localities and regions over the years. Their presence was positive related with the occurrence of algal turf and corals, but absent in the presence of coral rubble and fleshy macro-algae. Also, during the negative phase of ENSO/2011, the increase of algal turf favored the abundance of echinoids. Subsequent to ENSO, their density decreased but the richness of the echinoderm assemblage remained stable, suggesting that coral communities in the study area possess a strong resilience, where local abiotic and biotic factors maintain a dynamic balance in echinoderm populations.
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•Echinoderm community affects the composition and structure of coral reefs.•Changes in density and diversity can be observed at local and inter-annual level.•The cover of benthic groups determines the refuge and food for echinoderms.•ENSO events have ephemeral effect on the echinoderm dynamic at regional level.•Echinoderms have a balance linked the environmental variability of the region.
Summary
Background
The most commonly used second‐line Helicobacter pylori eradication regimens are bismuth‐containing quadruple therapy and levofloxacin‐containing triple therapy, both offering ...suboptimal results. Combining bismuth and levofloxacin may enhance the efficacy of rescue eradication regimens.
Aims
To evaluate the efficacy and tolerability of a second‐line quadruple regimen containing levofloxacin and bismuth in patients whose previous H. pylori eradication treatment failed.
Methods
This was a prospective multicenter study including patients in whom a standard triple therapy (PPI–clarithromycin–amoxicillin) or a non‐bismuth quadruple therapy (PPI–clarithromycin–amoxicillin–metronidazole, either sequential or concomitant) had failed. Esomeprazole (40 mg b.d.), amoxicillin (1 g b.d.), levofloxacin (500 mg o.d.) and bismuth (240 mg b.d.) was prescribed for 14 days. Eradication was confirmed by 13C‐urea breath test. Compliance was determined through questioning and recovery of empty medication envelopes. Incidence of adverse effects was evaluated by questionnaires.
Results
200 patients were included consecutively (mean age 47 years, 67% women, 13% ulcer). Previous failed therapy included: standard clarithromycin triple therapy (131 patients), sequential (32) and concomitant (37). A total of 96% took all medications correctly. Per‐protocol and intention‐to‐treat eradication rates were 91.1% (95%CI = 87–95%) and 90% (95%CI = 86–94%). Cure rates were similar regardless of previous (failed) treatment or country of origin. Adverse effects were reported in 46% of patients, most commonly nausea (17%) and diarrhoea (16%); 3% were intense but none was serious.
Conclusions
Fourteen‐day bismuth‐ and levofloxacin‐containing quadruple therapy is an effective (≥90% cure rate), simple and safe second‐line strategy in patients whose previous standard triple or non‐bismuth quadruple (sequential or concomitant) therapies have failed.
In the present work, we analyzed the linear and nonlinear model suitabilities for adsorption data from aqueous As(III) removal by manganese ferrite nanoparticles (NPs). Hence, As(III) adsorption onto ...ferrite NPs was formerly analyzed by the intraparticle diffusion model (IPD). Then, adsorption kinetics was described by the pseudo-first-order (PFO), pseudo-second-order (PSO), and Elovich models, while equilibrium adsorption was fitted to the Freundlich and Langmuir isotherms. Linear and nonlinear kinetic and isotherm models were solved and compared. The nonlinear data fitting was applied through the
lsqcurvefit
user-defined function (Matlab ver. 7.10.0). The initial adsorption rate was influenced by intraparticle diffusion and surface or film diffusion from the arsenic bulk solution to ferrite NPs, according to the IPD model. Adsorption kinetics of As(III) on manganese ferrite NPs was better described by the PSO model, followed by the Elovich model and then the PFO model. Equilibrium adsorption data were only worthily described by the Freundlich isotherm model. While the PSO, Elovich and Freundlich linear models showed even better fit than the nonlinear models, determinant bias was depicted for the PFO and Langmuir linear models. Thus, to use nonlinear adsorption models is highly advisable, having the Matlab
lsqcurvefit
function been proven very useful to face such task.
Summary
Employing genetic transformation using an Atcys‐3A cDNA construct expressing the cytosolic O‐acetylserine(thiol)lyase (OASTL), we obtained two Arabidopsis lines with different capabilities ...for supplying cysteine under metal stress conditions. Lines 1‐2 and 10‐10, grown under standard conditions, showed similar levels of cysteine and glutathione (GSH) to those of the wild‐type. However, in the presence of cadmium, line 10‐10 showed significantly higher levels. The increased thiol content allowed line 10‐10 to survive under severe heavy metal stress conditions (up to 400 µm of cadmium in the growth medium), and resulted in an accumulation of cadmium in the leaves to a level similar to that of metal hyperaccumulator plants. Investigation of the epidermal leaf surface clearly showed that most of the cadmium had accumulated in the trichomes. Furthermore, line 10‐10 was able to accumulate more cadmium in its trichomes than the wild‐type, whereas line 1‐2 showed a reduced capacity for cadmium accumulation. Our results suggest that an increased rate of cysteine biosynthesis is responsible for the enhanced cadmium tolerance and accumulation in trichome leaves. Thus, molecular engineering of the cysteine biosynthesis pathway, together with modification of the number of leaf trichomes, may have considerable potential in increasing heavy metal accumulation for phytoremediation purposes.
► In this study we developed a method to obtain human neural precursors by exfoliation. ► We obtained neural precursors from schizophrenic and bipolar disease patients. ► We cryo-preserved olfactory ...neural precursors in banks. ► Neural precursors showed cytoskeletal phenotypes typical of developing neurons. ► Neural precursors differentiate morphofunctionally and maintain voltage-operated Ca2+ currents.
Brain imaging and histopathological studies suggest that neurodevelopmental anomalies play a key role in the etiology of schizophrenia (SZ) and bipolar disorder (BD). New neuron formation and maturation occur in human olfactory epithelium throughout life. Therefore, the olfactory epithelium has been proposed as a model to study alterations in neurodevelopment, particularly in some psychiatric diseases. However, former studies were done with olfactory epithelium biopsies taken post mortem or under anesthesia from patients with SZ and BD. In this work we have developed a new method to obtain viable neural precursors by exfoliation of the anterior region of the medial lateral turbinate of the nasal cavity from healthy controls, and ambulatory patients. Cells were propagated to establish neural precursor banks. Thawed cells showed cytoskeletal phenotypes typical of developing neurons. They also conserved the ability to differentiate in presence of 2mM dibutyril-cyclic adenosine monophosphate, and maintained voltage-operated Ca2+ currents in culture. Moreover, proportions of neuronal maturation stages were maintained in cultured exfoliates obtained from SZ and BD patients. Data support that neural precursors obtained from a nasal exfoliate are an excellent experimental model to later approach studies on biomarkers, neural development and cellular alterations in the pathophysiology of SZ and BD.
Colorectal cancer (CRC) is one of the main causes of mortality. Recent studies suggest that cancer stem cells (CSCs) can survive after chemotherapy and promote tumor invasiveness and aggression. ...According to a higher hierarchy complexity of CSC, different protocols for isolation, expansion, and characterization have been used; however, there are no available resistance biomarkers that allow predicting the clinical response of treatment 5‑fluorouracil (5FU) and oxaliplatin. Therefore, the primary aim of the present study was to analyze the expression of gene resistance on tumors and CSC‑derived isolates from patients CRC. In the present study, adenocarcinomas of the colon and rectum (CRAC) were classified based on an
adenosine triphosphate‑based chemotherapy response assay, as sensitive and resistant and the percentage of CD24 and CD44 markers are evaluated by immunohistochemistry. To isolate resistant colon‑CSC, adenocarcinoma tissues resistant to 5FU and oxaliplatin were evaluated. Finally, all samples were sequenced using a custom assay with chemoresistance‑associated genes to find a candidate gene on resistance colon‑CSC. Results showed that 59% of the CRC tissue analyzed was resistant and had a higher percentage of CD44 and CD24 markers. An association was found in the expression of some genes between the tumor‑resistant tissue and CSC. Overall, isolates of the CSC population CD44
resistant to 5FU and oxaliplatin demonstrated different expression profiles; however, the present study was able to identify overexpression of the
gene, in most of the isolates. In conclusion, the results of the present study showed overexpression of
in CD44
cells is associated with chemoresistance to 5FU and oxaliplatin in CRAC.
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