A Comparative Study to Evaluate the Essential Work of Fracture to Measure the Fracture Toughness of Quasi-Brittle Material

In the present work, three different woven composite laminates were fabricated using the hand lay-up method. The woven reinforcement fibres were carbon fibres (CFRP), glass fibres (GFRP-W) and (GFRP-R) in combination with epoxy resin. Then, the central notch specimen tensile test (CNT) was used to measure the fracture toughness and the corresponding surface release energy (GIC). Then, the data were compared with the essential work of fracture (we) values based on the stored energy of the body to obtain a new standard fracture toughness test for composite laminates using relatively simple techniques. In addition to an extended finite element model, XFEM was implemented over a central notch specimen geometry to obtain a satisfactory validation of the essential work of fracture concepts. Therefore, the average values of (GIC) were measured with CNT specimens 25.15 kJ/m², 32.5 kJ/m² and 20.22 kJ/m² for CFRP, GFRP-W and GFRP-R, respectively. The data are very close as the percentage error for the surface release energy measured by the two methods was 0.83, 4.6 and 5.16 for carbon, glass and random fibre composite laminates, respectively. The data for the fracture toughness of XFEM are also very close. The percentage error is 4.6, 5.25 and 2.95 for carbon, glass and random fibre composite laminates, respectively. Therefore, the fundamental work of the fracture concept is highly recommended as a fracture toughness test for composite laminates or quasi-brittle Material.     

Surface Integrity of Dimethacrylate Composite Resins with Low Shrinkage Comonomers

The goal of current research was to investigate the influence of adding low shrinkage “Phene” like comonomers hexaethylene glycol bis(carbamate-isoproply-α-methylstyrene) (HE-Phene) and triethylene glycol bis(carbamate-isoproply-α-methylstyrene) (TE-Phene) on the surface and color characteristics of composite resin. A range of weight fractions (0, 10, 20, 30, 40 wt.%) of HE/TE-Phene monomers were mixed with bisphenol A glycidyl methacrylate (GMA)/triethylene glycol dimethacrylate (TEGDMA) monomer. Experimental composite resins were made by mixing 71 wt.% of silica fillers to 29 wt.% of the resin matrix. A Vickers indenter and glossmeter were used for testing surface hardness (SH) and gloss (SG) at 60°. A chewing-simulator was used to evaluate the surface wear after 15,000 cycles. Color change (∆E) and translucency parameter (TP) were measured using a spectrophotometer. Data showed that HE/TE-Phene monomer had no negative impact (p > 0.05) on surface gloss, wear, color change and translucency of experimental composite resins. Surface hardness was in a reducing direction with the increas in HE/TE-Phene weight fraction (p < 0.05). The study results suggested that incorporating HE/TE-Phene monomers up to 30 wt.% with Bis-GMA/TEGDMA resin did not negatively influence the surface integrity of composite resins except for SH.     

Fatigue failure load of immature anterior teeth: influence of different fiber post-core systems

Odontology - The aim was to explore the fracture-behavior, survival and marginal-microgaps within the root-canal of immature anterior teeth restored with different fiber-reinforced post-core...     

Single visit replacement of maxillary canine using fiber-reinforced composite resin

Missing a canine is of serious concern in social life of a patient in most of societies. While conventional fixed partial dentures and implant-supported restorations may often be the treatment of choice, fiber-reinforced composite (FRC) resins offer a conservative, fast and cost-effective alternative for single and multiple teeth replacement. This clinical report presents two cases where FRC technology was successfully used to restore canine edentulous area in terms of esthetic-cosmetic values and functionality.     

Characterization of a new fiber-reinforced flowable composite

Odontology - This study aimed to evaluate certain physical properties including surface wear of a new experimental short fiber-reinforced flowable resin composite (SFRC) in comparison with...     

Home Use of Mini-Dose Glucagon As a Novel Treatment for Hypoglycemia Following Repeated,Prolonged Fasts in Type 1 Diabetes During Ramadan

OBJECTIVEWe determined the efficacy of self-administered subcutaneous mini-dose glucagon (MDG) to treat fasting-induced hypoglycemia in type 1 diabetes (T1D).RESEARCH DESIGN AND METHODSThis was a 4-week randomized, controlled crossover trial of 2-week MDG or 2-week oral glucose tablets (OG, control) involving 17 adults with T1D during Ramadan.RESULTSCompared with OG, MDG demonstrated a significant higher change in blood glucose from baseline to 30 min (Δ^t30, P < 0.001) and 1 h (Δ^t60, P = 0.02). The efficacy of MDG was preserved following ≥8 h fasting with significantly higher Δ^t30 in MDG (P = 0.01). Over the entire 2 weeks, MDG period had increased time in 70–180 mg/dL (P = 0.009) and less time <70 mg/dL (P = 0.04). MDG use resulted in higher completion of fasts compared with OG (P < 0.001).CONCLUSIONSMDG administration is an effective alternative to OG for prevention and treatment of fasting-induced hypoglycemia, offering improved glycemic control and promoting successful completion of prolonged fasts.     

Tension pneumomediastinum and diffuse subcutaneous emphysema with severe acute respiratory syndrome coronavirus 2 infection requiring operative management for impending airway collapse: A case report

Tension pneumomediastinum is a rare complication of severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) infection that has increased in incidence with the novel coronavirus disease 2019 pandemic. Although traditionally managed with conservative measures, we present the indications and methods for the first operative management of tension pneumomediastinum with concomitant SARS‐CoV‐2 infection.     

A real-world study of user characteristics,safety and efficacy of open-source closed-loop systems and Medtronic 670G

We report a real-world evaluation of the first commercially approved automated insulin delivery (AID) system, MiniMed 670G (670G), and open source-automated insulin delivery (OS-AID) systems. This was undertaken as a retrospective observational study in adults with type 1 diabetes using AID systems for 6 months or longer in a publicly funded health service using clinically validated data. Sixty-eight adults (38 670G, 30 OS-AID systems) were included. OS-AID system users were younger, had a shorter diabetes duration and a higher education status. OS-AID systems displayed a significantly better change in HbA1c (median −0.9% [−0.4%, −1.1%] vs. −0.1% [IQR −0.7%, 0.2%], P = .004) and time in range 3.9-10 mmol/L (mean 78.5%, SD ± 12.0% vs. 68.2% ± 14.7%, P = .024) compared with 670G. Both systems showed minimal hypoglycaemia, with OS-AID systems revealing significantly improved secondary outcomes of mean glucose and percentage of time more than 10 mmol/L, with a higher percentage of time of less than 3 mmol/L. OS-AID system users displayed improved glycaemic outcomes with no clinical safety concerns compared with 670G, although higher weight-adjusted insulin dose and weight gain were noted. The study highlights key differences in OS-AID system user characteristics that are important for interpreting real-world findings from recent OS-AID system studies.     

Short fiber‐reinforced composite restorations: A review of the current literature

A newly‐recommended method for restoring large cavities is the biomimetic approach of using short fiber‐reinforced composite (SFRC) as dentine‐replacing material. The aim of the current review was to present an overview of SFRC and to give the clinician a detailed understanding of this new material and treatment strategy based on available‐literature review. A thorough literature search was done up to December 2017. The range of relevant publications was surveyed using PubMed and Google Scholar. From the search results, articles related to our search terms were only considered. The search terms used were “short fiber‐reinforced composite”, “everX posterior”, and “fiber‐reinforced composite restorations”. Of the assessed articles selected (N = 70), most were laboratory‐based research with various test specimen designs prepared according to the ISO standard or with extracted teeth; only four articles were clinical reports. A common finding was that by combining the SFRC as a bulk base with conventional composite, the load‐bearing capacity and failure mode of the material combination were improved, as compared to plain conventional composite restoration. In the reviewed studies, the biomimetic restoration technique of using SFRC showed promising characteristics, and therefore, might be recommended as an alternative treatment option for large cavities.