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201 result(s) for "Ahmed, Amgad S."
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Comparison of transverse dimensional and incisor changes between wide and narrow orthodontic archwires: a randomized controlled trial
Objectives To clinically compare the effects of broader archwires to standard archwires, using conventional brackets in both cases, on the transverse and incisor changes in maxillary and mandibular arches during leveling and alignment. Materials and methods Fifty-two patients presenting with crowding were allocated into two groups; one group received the broad Damon archwires while the other received standard 3M OrthoForm III Ovoid archwires. All participants were treated with conventional brackets using similar archwire sequences (0.014, 0.018, 0.016 × 0.022/0.016 × 0.025, 0.019 × 0.025 NiTi/CuNiTi archwires). Digital casts were obtained from alginate impressions before treatment (T0) and six weeks after inserting 0.019 × 0.025 NiTi archwires (T1). Pretreatment (T0) and post-alignment (T1) lateral cephalograms were obtained for each patient. The primary outcomes were the changes in the transverse arch dimensions and incisor inclination. The secondary outcomes were the horizontal and vertical linear changes in incisor position. Results Complete data were collected for 47 patients. There was a significant increase in arch width during treatment within each group, except for upper inter-molar width in 3M group ( P  = 0.071). Damon wire induced a statistically significant increase in maxillary inter-second premolar width ( P  = 0.042), and mandibular inter-first premolar ( P  = 0.043), inter-second premolar ( P  = 0.008) and inter-molar widths ( P  = 0.033) compared to 3M group. The increase in incisor proclination and the linear change in incisor position were significant within each group, with less mandibular incisor proclination ( P  = 0.004) and horizontal advancement ( P  = 0.038) in the Damon group. Conclusions Damon archwires created a comparatively greater increase in the maxillary inter-second premolar width and the mandibular inter-first premolar, inter-second premolar, and inter-molar widths, and less proclination and horizontal advancement in mandibular incisors. The study provides invaluable evidence that using broad archwires with self-ligating brackets is the reason behind any greater expansion observed in this system rather than the unique mechanical and biological features exerted by the self-ligating system. Clinical relevance Our results suggest that Damon archwire might be a better alternative compared to the narrower standard archwires that are usually used with conventional brackets, especially in the mandibular arch, in cases where mild to moderate crowding is planned to be resolved with a non-extraction approach. However, as arch expansion in the absence of posterior crossbites raises the question of long-term stability, the reported advantage of the use of wide wires should be interpreted with caution and should be considered in the retention phase, bearing in mind that achieving a good post-treatment occlusion is important for enhancing post-treatment stability.
Recovery of oxidized two-dimensional MXenes through high frequency nanoscale electromechanical vibration
MXenes hold immense potential given their superior electrical properties. The practical adoption of these promising materials is, however, severely constrained by their oxidative susceptibility, leading to significant performance deterioration and lifespan limitations. Attempts to preserve MXenes have been limited, and it has not been possible thus far to reverse the material’s performance. In this work, we show that subjecting oxidized micron or nanometer thickness dry MXene films—even those constructed from nanometer-order solution-dispersed oxidized flakes—to just one minute of 10 MHz nanoscale electromechanical vibration leads to considerable removal of its surface oxide layer, whilst preserving its structure and characteristics. Importantly, electrochemical performance is recovered close to that of their original state: the pseudocapacitance, which decreased by almost 50% due to its oxidation, reverses to approximately 98% of its original value, with good capacitance retention ( ≈ 93%) following 10,000 charge–discharge cycles at 10 A g −1 . These promising results allude to the exciting possibility for rejuvenating the material for reuse, therefore offering a more economical and sustainable route that improves its potential for practical translation. Despite their vast potential, the practical deployment of MXenes has been hampered by their tendency to be oxidized. Here, the authors show that simply vibrating MXene films in just a minute can remove the oxide layer formed and restore their electrochemical performance close to its original state.
Novel Cold Cure Acrylic Denture Base with Recycled Zirconia Nano-Fillers That Were Functionalized by HEMA Agent Incorporation: Using the Sprinkle Approach
Background: Though acrylic resins possess many useful properties, denture fracture is nevertheless a familiar issue. Objective: This study aimed to determine the effect of low-percent recycled Zirconia nanoparticles as filler on the transverse strength, impact strength, surface hardness, water sorption, and solubility of resin using the sprinkle cold-curing technique. Materials and Methods: Various formulae were prepared and mixed with PMMA (polymer) powder containing varying percentages (0.01%, 0.1%, 0.3%, and 0.5%) of recycled Zr[O.sub.2]NPs to mono-methyl methacrylate (MMA monomer). A 2-hydroxyethylmethacrylate (HEMA) agent was used to functionalize recycled zirconia (Zr[O.sub.2]) nano-fillers. X-ray diffraction, field emission scanning electron microscopy, high-resolution transmission electron microscopy, energy-dispersive X-ray spectroscopy, and dynamic light scattering were used to characterize the samples. For mechanical tests, standard metallic moulds (according to American Dental Association specification no. 27) were machined for 60 specimens' preparation, 12 for each percent (zero, 0.01%, 0.1%, 0.3%, and 0.5%). A one-way ANOVA test was used to compare the five groups for parametric data, while the Kruskal-Wallis test was employed for nonparametric data. The P 0.05 value was accepted as the significance level. All formulae were tested for cytotoxicity at 24 and 48 hours on WI38 normal lung cell lines. Results: The XRD analysis demonstrated the tetragonal crystallographic structure of the recycled zirconia nanoparticles. Incorporating a low percentage of recycled Zr[O.sub.2] nanoparticles (0.01%, 0.1%, 0.3%, and 0.5%) improved the tested properties of PMMA to different degrees in a significant and non-significant pattern, while the optimal tested percent was 0.3%. Conclusion: The 0.3% percentage of recycled zirconia nanoparticles maintained and improved the physical and mechanical properties of acrylic resin. Recycled Zr[O.sub.2]/PMMA nanocomposite is a synergistic candidate due to its economic return and clinical application safety. Keywords: acrostone, cold cure, novel, recycled zirconia, sprinkle
Exploiting the Biosynthetic Potency of Taxol from Fungal Endophytes of Conifers Plants; Genome Mining and Metabolic Manipulation
Endophytic fungi have been considered as a repertoire for bioactive secondary metabolites with potential application in medicine, agriculture and food industry. The biosynthetic pathways by fungal endophytes raise the argument of acquisition of these machineries of such complex metabolites from the plant host. Diterpenoids “Taxol” is the most effective anticancer drug with highest annual sale, since its discovery in 1970 from the Pacific yew tree, Taxus brevifolia. However, the lower yield of Taxol from this natural source (bark of T. brevifolia), availability and vulnerability of this plant to unpredicted fluctuation with the ecological and environmental conditions are the challenges. Endophytic fungi from Taxus spp. opened a new avenue for industrial Taxol production due to their fast growth, cost effectiveness, independence on climatic changes, feasibility of genetic manipulation. However, the anticipation of endophytic fungi for industrial Taxol production has been challenged by the loss of its productivity, due to the metabolic reprograming of cells, downregulating the expression of its encoding genes with subculturing and storage. Thus, the objectives of this review were to (1) Nominate the endophytic fungal isolates with the Taxol producing potency from Taxaceae and Podocarpaceae; (2) Emphasize the different approaches such as molecular manipulation, cultural optimization, co-cultivation for enhancing the Taxol productivities; (3) Accentuate the genome mining of the rate-limiting enzymes for rapid screening the Taxol biosynthetic machinery; (4) Triggering the silenced rate-limiting genes and transcriptional factors to activates the biosynthetic gene cluster of Taxol.
Impact of tumor size on the outcomes of hepatic resection for hepatocellular carcinoma: a retrospective study
Background To evaluate the impact of tumor size on the perioperative and long-term outcomes of liver resection for hepatocellular carcinoma (HCC). Methods We reviewed the patients’ data who underwent liver resection for HCC between November 2009 and 2019. Patients were divided into 3 groups according to the tumor size. Group I: HCC < 5 cm, Group II: HCC between 5 to 10 cm, and Group III: HCC ≥ 10 cm in size. Results Three hundred fifteen patients were included in the current study. Lower platelets count was noted Groups I and II. Higher serum alpha-feto protein was noted in Group III. Higher incidence of multiple tumors, macroscopic portal vein invasion, nearby organ invasion and presence of porta-hepatis lymph nodes were found in Group III. More major liver resections were performed in Group III. Longer operation time, more blood loss and more transfusion requirements were found in Group III. Longer hospital stay and more postoperative morbidities were noted in Group III, especially posthepatectomy liver failure, and respiratory complications. The median follow-up duration was 17 months (7–110 months). Mortality occurred in 100 patients (31.7%) and recurrence occurred in 147 patients (46.7%). There were no significant differences between the groups regarding recurrence free survival (Log Rank, p  = 0.089) but not for overall survival (Log Rank, p  = 0.001). Conclusion HCC size is not a contraindication for liver resection. With proper selection, safe techniques and standardized care, adequate outcomes could be achieved.
Phenylboronic Acid-Grafted Chitosan Nanocapsules for Effective Delivery and Controllable Release of Natural Antioxidants: Olive Oil and Hydroxytyrosol
Olives and virgin olive oil (VOO) are a staple of Mediterranean diets and are rich in several beneficial phenolic compounds, including hydroxytyrosol (HT). Therefore, VOO was extracted from Koroneiki olive fruits, and its volatile as well as phenolic components were identified. Meanwhile, in order to upgrade the pharmaceutical capabilities of VOO and HT, a new conjugate phenylboronic acid-chitosan nanoparticles (PBA-CSNPs, NF-1) was fabricated and applied as nanocapsules for implanting high loading and efficient delivery of VOO and HT nanoformulations (NF-2 and NF-3). Due to the H-bonding interactions and boronate ester formation between the hydroxyl groups of the phenolic content of VOO or HT and the PBA groups in the nanocapsules (NF-1), VOO and HT were successfully loaded into the PBA-CSNPs nanocapsules with high loading contents and encapsulation efficacies. The NF-2 and NF-3 nanoformulations demonstrated physicochemical stability, as revealed by their respective zeta potential values, and pH-triggered drug release characteristics. The in vitro studies demonstrated that the nascent nanocapsules were almost completely nontoxic to both healthy and cancer cells, whereas VOO-loaded (NF-2) and HT-loaded nanocapsules (NF-3) showed efficient anti-breast cancer efficiencies. In addition, the antimicrobial and antioxidant potentials of VOO and HT were significantly improved after nanoencapsulation.
High Frequency Sonoprocessing: A New Field of Cavitation‐Free Acoustic Materials Synthesis, Processing, and Manipulation
Ultrasound constitutes a powerful means for materials processing. Similarly, a new field has emerged demonstrating the possibility for harnessing sound energy sources at considerably higher frequencies (10 MHz to 1 GHz) compared to conventional ultrasound (⩽3 MHz) for synthesizing and manipulating a variety of bulk, nanoscale, and biological materials. At these frequencies and the typical acoustic intensities employed, cavitation—which underpins most sonochemical or, more broadly, ultrasound‐mediated processes—is largely absent, suggesting that altogether fundamentally different mechanisms are at play. Examples include the crystallization of novel morphologies or highly oriented structures; exfoliation of 2D quantum dots and nanosheets; polymer nanoparticle synthesis and encapsulation; and the possibility for manipulating the bandgap of 2D semiconducting materials or the lipid structure that makes up the cell membrane, the latter resulting in the ability to enhance intracellular molecular uptake. These fascinating examples reveal how the highly nonlinear electromechanical coupling associated with such high‐frequency surface vibration gives rise to a variety of static and dynamic charge generation and transfer effects, in addition to molecular ordering, polarization, and assembly—remarkably, given the vast dimensional separation between the acoustic wavelength and characteristic molecular length scales, or between the MHz‐order excitation frequencies and typical THz‐order molecular vibration frequencies. Recent work has shown that high‐frequency acoustic vibration at MHz‐order frequencies offers vast opportunities for manipulating bulk/2D crystals and biological materials distinct from conventional sonochemical processes at lower frequencies, therefore opening up a new field of cavitation‐free materials synthesis and processing.
Molecular Docking and Dynamics Simulation Study of Hyrtios erectus Isolated Scalarane Sesterterpenes as Potential SARS-CoV-2 Dual Target Inhibitors
Presently, the world is under the toll of pandemic coronavirus disease-2019 (COVID-19) outbreak caused by SARS-CoV-2. Lack of effective and safe therapeutics has stressed the scientific community for developing novel therapeutics capable of alleviating and stopping this pandemic. Within the presented study, molecular docking, ADME properties and all-atom molecular dynamic (MD) simulation, along with two standard antiviral agents (lopinavir and benzopurpurin-4B), were applied to investigate 15 scalaranes sesterterpenes natural compounds, purified from the Red Sea marine sponge Hyrtios erectus, as potential COVID-19 dual-target inhibitors. Following multi-step docking within COVID-19 main protease and Nsp15 endoribonuclease cavities, nine promising drug-like compounds exhibited higher docking scores as well as better interactions with the target’s crucial residues than those of reference ligands. Compounds 2, 6, 11, and 15, were predicted to simultaneously subdue the activity of the two COVID-19 targets. Dynamics behavior of the best-docked molecules, compounds 15 and 6, within COVID-19 target pockets showed substantial stability of ligand-protein complexes as presented via several MD simulation parameters. Furthermore, calculated free-binding energies from MD simulation illustrated significant ligand’s binding affinity towards respective target pockets. All provided findings supported the utility of scalarane-based sesterterpenes, particularly compounds 15 and 6, as promising lead candidates guiding the development of effective therapeutics against SARS-CoV-2.
Migraine and the risk of cardiovascular and cerebrovascular events: a meta-analysis of 16 cohort studies including 1 152 407 subjects
ObjectivesTo perform an updated meta-analysis to evaluate the long-term cardiovascular and cerebrovascular outcomes among migraineurs.SettingA meta-analysis of cohort studies performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines.Data sourcesThe MEDLINE, Web of Science and Cochrane Central Register of Controlled Trials databases were searched for relevant articles.ParticipantsA total of 16 cohort studies (18 study records) with 394 942 migraineurs and 757 465 non-migraineurs were analysed.Primary and secondary outcome measuresMajor adverse cardiovascular and cerebrovascular events (MACCE), stroke (ie, ischaemic, haemorrhagic or non-specified), myocardial infarction (MI) and all-cause mortality. The outcomes were reported at the longest available follow-up.Data analysisSummary-adjusted hazard ratios (HR) were calculated by random-effects Der-Simonian and Liard model. The risk of bias was assessed by the Newcastle-Ottawa Scale.ResultsMigraine was associated with a higher risk of MACCE (adjusted HR 1.42, 95% confidence interval [CI] 1.26 to 1.60, P<0.001, I2=40%) driven by a higher risk of stroke (adjusted HR 1.41, 95% CI 1.25 to 1.61, P<0.001, I2=72%) and MI (adjusted HR 1.23, 95% CI 1.03 to 1.43, P=0.006, I2=59%). There was no difference in the risk of all-cause mortality (adjusted HR 0.93, 95% CI 0.78 to 1.10, P=0.38, I2=91%), with a considerable degree of statistical heterogeneity between the studies. The presence of aura was an effect modifier for stroke (adjusted HR aura 1.56, 95% CI 1.30 to 1.87 vs adjusted HR no aura 1.11, 95% CI 0.94 to 1.31, P interaction=0.01) and all-cause mortality (adjusted HR aura 1.20, 95% CI 1.12 to 1.30 vs adjusted HR no aura 0.96, 95% CI 0.86 to 1.07, Pinteraction<0.001).ConclusionMigraine headache was associated with an increased long-term risk of cardiovascular and cerebrovascular events. This effect was due to an increased risk of stroke (both ischaemic and haemorrhagic) and MI. There was a moderate to severe degree of heterogeneity for the outcomes, which was partly explained by the presence of aura.PROSPERO registration number CRD42016052460.
Optimizing greenhouse microclimate for plant pathology: challenges and cooling solutions for pathogen control in arid regions
Crop production using greenhouse technology has become increasingly essential for intensifying agricultural output, particularly in regions with challenging climatic conditions. More so, greenhouses do not only support continuous crop supply but also provide a controlled environment crucial for studying plant-pathogen interaction. Likewise, pests and diseases are a constant threat to crop production, which requires innovative control methods. Providing a suitable and sustainable control method requires a detailed probe into the relationship between plants and biotic disturbance under controlled settings. Therefore this review explores the relationships between plants and pathogens, highlighting the impact of extreme greenhouse microclimates on plant pathology assays. Given the extreme weather conditions in the Arabian peninsula, the efficiency of greenhouses, especially during summer, is compromised without adequate cooling systems. This review discusses the current strategies employed to optimize greenhouse conditions in hot arid regions, aiming to enhance plant health by mitigating pathogen activity while minimizing energy, and water consumption. The review also provides an overview of how microclimatic parameters within greenhouses influence plant-pathogen dynamics, ensuring conditions that are conducive to managing both biotic and abiotic diseases. Additionally, the review aims to evaluate various cooling techniques available and most widely accepted in hot arid regions. Moreover, the performance indicators, principles, and effectiveness of each technique are discussed. Promising advances in the manipulations and combination of these techniques have proven to maintain an appropriate greenhouse microclimate with minimal resource use.