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Dental Materials : Official Publication... Jun 2016A systematic review was conducted to assess the effects of air-particle abrasion procedures on the mechanical strength and phase transformation of yttria-stabilized... (Meta-Analysis)
Meta-Analysis Review
OBJECTIVES
A systematic review was conducted to assess the effects of air-particle abrasion procedures on the mechanical strength and phase transformation of yttria-stabilized tetragonal zirconia polycrystal (Y-TZP).
DATA
This report followed the PRISMA Statement. From 1013 eligible studies, 78 were selected for full-text analysis, from which 37 were excluded. The 41 remaining papers were included for the systematic review; hand-searching yielded three papers. The review comprised a total of 44 studies; 21 were included in the meta-analysis.
SOURCES
Searches were performed with no publication year limit through November 2015 in PubMed/MEDLINE, Web of Science (Core Collection) and Scopus databases.
STUDY SELECTION
In vitro studies evaluating the effect of air-particle abrasion protocols on the mechanical strength and/or phase transformation of Y-TZP zirconia specimens, immediately or after aging. For the meta-analysis, flexural strength data of air-particle abrasion vs. control (nonabraded) were globally and subgroup analyzed. Subgroup analyses assessed blasting parameters (particle size, pressure, or time duration) and the effect of aging. Statistical analyses were conducted using RevMan 5.1 (Cochrane Collaboration, Copenhagen, Denmark). Comparisons were performed with random-effect models at a 5% significance level. Phase transformation data were included only in the systematic review, as insufficient data were available for meta-analysis.
CONCLUSIONS
Airborne-particle abrasion improved flexural strength of Y-TZP, regardless of abrasion parameters and the presence or lack of aging (p≤0.05). Phase transformation tended to be increased by air abrasion immediately or with up to 2h of aging. However, after aging for 12h or more, the abraded Y-TZP showed less monoclinic content than the control.
Topics: Humans; Materials Testing; Pressure; Surface Properties; Tooth Abrasion; Yttrium; Zirconium
PubMed: 27083253
DOI: 10.1016/j.dental.2016.03.021 -
Environmental Pollution (Barking, Essex... Nov 2022Exposure measurement error is an important source of bias in epidemiological studies. We assessed the validity of employing ambient (outdoor) measurements as proxies of... (Meta-Analysis)
Meta-Analysis Review
Exposure measurement error is an important source of bias in epidemiological studies. We assessed the validity of employing ambient (outdoor) measurements as proxies of personal exposures at individual levels focusing on fine particles (PM) and black carbon (BC)/elemental carbon (EC) on a global scale. We conducted a systematic review and meta-analysis and searched databases (ISI Web of Science, Scopus, PubMed, Ovid MEDLINE®, Ovid Embase, and Ovid BIOSIS) to retrieve observational studies in English language published from 1 January 2006 until 5 May 2021. Correlation coefficients (r) between paired ambient (outdoor) concentration and personal exposure for PM or BC/EC were standardized as effect size. We used random-effects meta-analyses to pool the correlation coefficients and investigated the causes of heterogeneity and publication bias. Furthermore, we employed subgroup and meta-regression analyses to evaluate the modification of pooled estimates by potential mediators. This systematic review identified thirty-two observational studies involving 1744 subjects from ten countries, with 28 studies for PM and 11 studies for BC/EC. Personal PM exposure is more strongly correlated with ambient (outdoor) concentrations (0.63, 95% confidence interval [CI]: 0.57-0.68) than personal BC/EC exposure (0.49, 95% CI: 0.38-0.59), with significant differences in ṝ (0.14, 95% CI: 0.03-0.25; p < 0.05). The results demonstrated that the health status of participants was a significant modifier of pooled correlations. In addition, the personal to ambient (P/A) ratio for PM and average ambient BC/EC levels were potential effect moderators of the pooled ṝ. The funnel plots and Egger's regression test indicated inevident publication bias. The pooled estimates were robust through sensitivity analyses. The results support the growing consensus that the validity coefficient of proxy measures should be addressed when interpreting results from epidemiological studies to better understand how strong health outcomes are affected by different levels of PM and their components.
Topics: Air Pollutants; Carbon; Databases, Factual; Environmental Exposure; Humans; Particulate Matter; Regression Analysis; Soot
PubMed: 36037851
DOI: 10.1016/j.envpol.2022.120030 -
Ecological Applications : a Publication... Mar 2020As a consequence of the global ubiquity of plastic pollution, scientists, decision-makers, and the public often ask whether macroplastics (>5 mm) and microplastics... (Meta-Analysis)
Meta-Analysis
As a consequence of the global ubiquity of plastic pollution, scientists, decision-makers, and the public often ask whether macroplastics (>5 mm) and microplastics (<5 mm) have a realized ecological threat. In 2016, we conducted a systematic review of the literature and made a call for further research testing hypotheses about ecological effects. In the subsequent years, the amount of relevant research has risen tremendously. Here, we reassess the literature to determine the current weight of evidence about the effects of plastic pollution across all levels of biological organization. Our data spans marine, freshwater, and terrestrial environments. We extracted data from 139 lab and field studies testing 577 independent effects across a variety of taxa and with various types, sizes, and shapes of plastic. Overall, 59% of the tested effects were detected. Of these, 58% were due to microplastics and 42% were due to macroplastics. Of the effects that were not detected, 94% were from microplastics and 6% were from macroplastics. We found evidence that whether or not an effect is detected, as well as the severity and direction of the effect, is driven by dose, particle shape, polymer type, and particle size. Based on our analyses, there is no doubt that macroplastics are causing ecological effects, however, the effects of microplastics are much more complex. We also assessed the environmental relevancy of experimental studies by comparing the doses used in each exposure to the concentrations and sizes of microplastics found in the environment. We determined that only 17% of the concentrations used in experimental studies have been found in nature, and that 80% of particle sizes used in experiments fall below the size range of the majority of environmental sampling. Based on our systematic review and meta-analysis, we make a call for future work that recognizes the complexity of microplastics and designs tests to better understand how different types, sizes, shapes, doses, and exposure durations affect wildlife. We also call for more ecologically and environmentally relevant studies, particularly in freshwater and terrestrial environments.
Topics: Environmental Monitoring; Environmental Pollution; Fresh Water; Microplastics; Plastics; Water Pollutants, Chemical
PubMed: 31758826
DOI: 10.1002/eap.2044 -
A systematic review on the composting of green waste: Feedstock quality and optimization strategies.Waste Management (New York, N.Y.) Jul 2018Green waste (GW) is an important fraction of municipal solid waste (MSW). The composting of lignocellulosic GW is challenging due to its low decomposition rate.... (Review)
Review
Green waste (GW) is an important fraction of municipal solid waste (MSW). The composting of lignocellulosic GW is challenging due to its low decomposition rate. Recently, an increasing number of studies that include strategies to optimize GW composting appeared in the literature. This literature review focuses on the physicochemical quality of GW and on the effect of strategies used to improve the process and product quality. A systematic search was carried out, using keywords, and 447 papers published between 2002 and 2018 were identified. After a screening process, 41 papers addressing feedstock quality and 32 papers on optimization strategies were selected to be reviewed and analyzed in detail. The GW composition is highly variable due to the diversity of the source materials, the type of vegetation, and climatic conditions. This variability limits a strict categorization of the GW physicochemical characteristics. However, this research established that the predominant features of GW are a C/N ratio higher than 25, a deficit in important nutrients, namely nitrogen (0.5-1.5% db), phosphorous (0.1-0.2% db) and potassium (0.4-0.8% db) and a high content of recalcitrant organic compounds (e.g. lignin). The promising strategies to improve composting of GW were: i) GW particle size reduction (e.g. shredding and separation of GW fractions); ii) addition of energy amendments (e.g. non-refined sugar, phosphate rock, food waste, volatile ashes), bulking materials (e.g. biocarbon, wood chips), or microbial inoculum (e.g. fungal consortia); and iii) variations in operating parameters (aeration, temperature, and two-phase composting). These alternatives have successfully led to the reduction of process length and have managed to transform recalcitrant substances to a high-quality end-product.
Topics: Composting; Nitrogen; Phosphorus; Soil; Solid Waste
PubMed: 29709309
DOI: 10.1016/j.wasman.2018.04.037 -
Odontology Oct 2023This systematic review evaluated the effects of nano-sized cement particles on the properties of calcium silicate-based cements (CSCs). Using defined keywords, a... (Review)
Review
This systematic review evaluated the effects of nano-sized cement particles on the properties of calcium silicate-based cements (CSCs). Using defined keywords, a literature search was conducted to identify studies that investigated properties of nano-calcium silicate-based cements (NCSCs). A total of 17 studies fulfilled the inclusion criteria. Results indicated that NCSC formulations have favourable physical (setting time, pH and solubility), mechanical (push out bond strength, compressive strength and indentation hardness) and biological (bone regeneration and foreign body reaction) properties compared with commonly used CSCs. However, the characterization and verification for the nano-particle size of NCSCs were deficient in some studies. Furthermore, the nanosizing was not limited to the cement particles and a number of additives were present. In conclusion, the evidence available for the properties of CSC particles in the nano-range is deficient-such properties could be a result of additives which may have enhanced the properties of the material.
Topics: Oxides; Materials Testing; Calcium Compounds; Silicates; Dental Cements; Glass Ionomer Cements; Drug Combinations
PubMed: 36864211
DOI: 10.1007/s10266-023-00786-0 -
Heliyon Apr 2021Metal-organic frameworks (MOFs) are a fascinating class of crystalline porous materials composed of metal ions and organic ligands. Due to their attractive properties,... (Review)
Review
Metal-organic frameworks (MOFs) are a fascinating class of crystalline porous materials composed of metal ions and organic ligands. Due to their attractive properties, MOFs can potentially offer biomedical field applications, such as drug delivery and imaging. This study aimed to systematically identify the affecting factors on the MOF characteristics and their effects on structural and biological characteristics. An electronic search was performed in four databases containing PubMed, Scopus, Web of Science, and Embase, using the relevant keywords. After analyzing the studies, 20 eligible studies were included in this review. As a result, various factors such as additives and organic ligand can influence the size and structure of MOFs. Additives are materials that can compete with ligand and may affect the nucleation and growth processes and, consequently, particle size. The nature and structure of ligand are influential in determining the size and structure of MOF. Moreover, synthesis parameters like the reaction time and initial reagents ratio are critical factors that should be optimized to regulate the size and structure. Of note is that the nature of the ligand and using a suitable additive can control the porosity of MOF. The more extended ligands aid in forming large pores. The choice of metallic nodes and organic ligand, and the MOF concentration are important factors since they can determine toxicity and biocompatibility of the final structure. The physicochemical properties of MOFs, such as hydrophobicity, affect the toxicity of nanoparticles. An increase in hydrophobicity causes increased toxicity of MOF. The biodegradability of MOF, as another property, depends on the organic ligand and metal ion and environmental conditions like pH. Photocleavable ligands can be served for controlled degradation of MOFs. Generally, by optimizing these affecting factors, MOFs with desirable properties will be obtained for biomedical applications.
PubMed: 33997421
DOI: 10.1016/j.heliyon.2021.e06914 -
Radiotherapy and Oncology : Journal of... Oct 2022Recently, a number of clinical studies have explored links between possible Relative Biological Effectiveness (RBE) elevations and patient toxicities and/or image... (Review)
Review
Recently, a number of clinical studies have explored links between possible Relative Biological Effectiveness (RBE) elevations and patient toxicities and/or image changes following proton therapy. Our objective was to perform a systematic review of such studies. We applied a "Problem [RBE], Intervention [Protons], Population [Patients], Outcome [Side effect]" search strategy to the PubMed database. From our search, we retrieved studies which: (a) performed novel voxel-wise analyses of patient effects versus physical dose and LET (n = 13), and (b) compared image changes between proton and photon cohorts with regard to proton RBE (n = 9). For each retrieved study, we extracted data regarding: primary tumour type; size of patient cohort; type of image change studied; image-registration method (deformable or rigid); LET calculation method, and statistical methodology. We compared and contrasted their methods in order to discuss the weight of clinical evidence for variable proton RBE. We concluded that clinical evidence for variable proton RBE remains statistically weak at present. Our principal recommendation is that proton centres and clinical trial teams collaborate to standardize follow-up protocols and statistical analysis methods, so that larger patient cohorts can ultimately be considered for RBE analyses.
Topics: Humans; Relative Biological Effectiveness; Proton Therapy; Protons; Linear Energy Transfer; Radiotherapy Planning, Computer-Assisted
PubMed: 35988776
DOI: 10.1016/j.radonc.2022.08.014 -
Ecotoxicology and Environmental Safety Feb 2024The extensive application of amorphous silica nanoparticles (aSiNPs) in recent years has resulted in unavoidable human exposure in daily life, thus raising widespread... (Review)
Review
The extensive application of amorphous silica nanoparticles (aSiNPs) in recent years has resulted in unavoidable human exposure in daily life, thus raising widespread concerns regarding the safety of aSiNPs on human health. The particle size is one of the important characteristics of nanomaterials that could influence their toxicity. For the reason that particles with smaller sizes possess larger surface area, which may lead to higher surface activity and biological reactivity. However, due to the complexity of experimental conditions and biological systems, the relationship between the particle size and the toxic effect of aSiNPs remains unclear. Therefore, this systematic review aims to investigate how particle size influences the toxic effect of aSiNPs in vivo and to analyze the relevant experimental factors affecting the size-dependent toxicity of aSiNPs in vivo. We found that 83.8% of 35 papers included in the present review came to the conclusion that smaller-sized aSiNPs exhibited stronger toxicity, though a few papers (6 papers) put forward different opinions. The reasons for smaller aSiNPs manifested greater toxicity were summarized. In addition, certain important experimental factors could influence the size-dependent effects and in vivo toxicity of aSiNPs, such as the synthesis method of aSiNPs, disperse medium of aSiNPs, administration route of aSiNPs, species or strain of experimental animals, sex of experimental animals, aggregation/agglomeration and protein corona of aSiNPs.
Topics: Animals; Humans; Silicon Dioxide; Nanoparticles; Particle Size
PubMed: 38199222
DOI: 10.1016/j.ecoenv.2023.115910 -
The American Journal of Clinical... Oct 2021LDL particle size and number (LDL-P) are emerging lipid risk factors. Nonsystematic reviews have suggested that diets lower in carbohydrates and higher in fats may... (Meta-Analysis)
Meta-Analysis
Effect of carbohydrate-restricted dietary interventions on LDL particle size and number in adults in the context of weight loss or weight maintenance: a systematic review and meta-analysis.
BACKGROUND
LDL particle size and number (LDL-P) are emerging lipid risk factors. Nonsystematic reviews have suggested that diets lower in carbohydrates and higher in fats may result in increased LDL particle size when compared with higher-carbohydrate diets.
OBJECTIVES
This study aimed to systematically review available evidence and conduct meta-analyses of studies addressing the association of carbohydrate restriction with LDL particle size and LDL-P.
METHODS
We searched 6 electronic databases on 4 January, 2021 for randomized trials of any length that reported on dietary carbohydrate restriction (intervention) compared with higher carbohydrate intake (control). We calculated standardized mean differences (SMDs) in LDL particle size and LDL-P between the intervention and control groups of eligible studies, and pooled effect sizes using random-effects models. We performed prespecified subgroup analyses and examined the effect of potential explanatory factors. Internal validity and publication bias were assessed using Cochrane's risk-of-bias tool and funnel plots, respectively. Studies that could not be meta-analyzed were summarized qualitatively.
RESULTS
This review summarizes findings from 38 randomized trials including a total of 1785 participants. Carbohydrate-restricted dietary interventions were associated with an increase in LDL peak particle size (SMD = 0.50; 95% CI: 0.15, 0.86; P < 0.01) and a reduction in LDL-P (SMD = -0.24; 95% CI: -0.43, -0.06; P = 0.02). The effect of carbohydrate-restricted dietary interventions on LDL peak particle size appeared to be partially explained by differences in weight loss between intervention groups and exploratory analysis revealed a shift from small dense to larger LDL subclasses. No statistically significant association was found between carbohydrate-restricted dietary interventions and mean LDL particle size (SMD = 0.20; 95% CI: -0.29, 0.69; P = 0.37).
CONCLUSIONS
The available evidence indicates that dietary interventions restricted in carbohydrates increase LDL peak particle size and decrease the numbers of total and small LDL particles.This review was registered at www.crd.york.ac.uk/prospero/ as CRD42020188745.
Topics: Cholesterol, LDL; Dietary Carbohydrates; Humans; Weight Loss
PubMed: 34159352
DOI: 10.1093/ajcn/nqab212 -
The Science of the Total Environment Feb 2023Microplastics (<5 mm) (MPs) are widely distributed throughout the world, and their accumulation and migration in the environment have caused health and safety concerns.... (Review)
Review
Microplastics (<5 mm) (MPs) are widely distributed throughout the world, and their accumulation and migration in the environment have caused health and safety concerns. Currently, most of the reviewed literatures mainly focus on the distribution in various environmental media, adsorption mechanisms with different pollutants, and characterization of MPs. Therefore, the present review mainly highlights the characterization techniques of MPs and the underlying mechanisms of their combination with conventional coexisting substances (heavy metals, organic pollutants, and nutrients). We observed that massive MP pollution has been found in many areas, especially in Africa, Asia, India, South Africa, North America and Europe. The separation methods of MPs in different environmental media are basically similar, including sampling, pre-treatment, flotation, filtration and digestion. The combination of multiple characterization technologies can more precisely identify the shape, abundance, colour, and particle size of MPs. Notably, although recent reports have confirmed that MPs can act as carriers of heavy metals and carry them into organisms to cause harm, MPs have different adsorption and desorption characteristics for various heavy metals. The adsorption capacity of organic pollutants onto MPs is closely related to their hydrophobicity, specific surface area and functional group characteristics. The relative abundance of MPs in sediments and lakes had a significantly positive correlation with the mass concentration of total nitrogen in lake water, but this finding still needs to be further verified. Based on current research, we suggest that future MP research should focus on characterization technology, environmental migration, ecological effects, health risks and degradation methods.
Topics: Microplastics; Plastics; Environmental Pollutants; Water Pollutants, Chemical; Metals, Heavy; South Africa
PubMed: 36423843
DOI: 10.1016/j.scitotenv.2022.160151