Rheological Behavior of High-Performance Shotcrete Mixtures Containing Colloidal Silica and Silica Fume Using the Bingham Model

There have been numerous studies on shotcrete based on strength and durability. However, few studies have been conducted on rheological characteristics, which are very important parameters for evaluating the pumpability and shootability of shotcrete. In those studies, silica fume has been generally used as a mineral admixture to simultaneously enhance the strength, durability, pumpability, and shootability of shotcrete. Silica fume is well-known to significantly increase the viscosity of a mixture and to prevent material sliding at the receiving surface when used in shotcrete mixtures. However, the use of silica fume in shotcrete increases the possibility of plastic shrinkage cracking owing to its very high fineness, and further, silica fume increases the cost of manufacturing the shotcrete mixture because of its cost and handling. Colloidal silica is a new material in which nano-silica is dispersed in water, and it could solve the above-mentioned problems. The purpose of this research is to develop high-performance shotcrete with appropriate levels of strength and workability as well as use colloidal silica for normal structures without a tunnel structure. Thereafter, the workability of shotcrete with colloidal silica (2, 3, and 4%) was evaluated with a particle size of 10 nm and silica fume replacement (4 and 7%) of cement. In this study, an air-entraining agent for producing high-performance shotcrete was also used. The rheological properties of fresh shotcrete mixtures were estimated using an ICAR rheometer and the measured rheological parameters such as flow resistance and torque viscosity were correlated with the workability and shootability. More appropriate results will be focusing on the Bingham model properties such that the main focus here is to compare all data using the Bingham model and its performance. The pumpability, shootability, and build-up thickness characteristics were also evaluated for the performance of the shotcrete. This research mainly focuses on the Bingham model for absolute value because it creates an exact linear line in a graphical analysis, which provides more appropriate results for measuring the shotcrete performance rather than ICAR rheometer relative data.     

Patterns of attendances to the hospital emergency eye care service: a multicentre study in England

Background/ObjectivesTo characterise the patterns of presentation and diagnostic frequencies in Hospital Emergency Eye Care Services (HEECS) across 13 hospitals in England.MethodsRetrospective, cross-sectional, observational multi-centre (n = 13) study to assess HEECS attendances over a 28-day study period. Data derived included: number of consecutive attendances, patient demographics and diagnoses. Age and gender variations, the impact of day of the week on attendance patterns, diagnostic frequencies and estimates of the annual incidence and attendance rates were evaluated.ResultsA total of 17,667 patient (mean ± standard deviation age = 49.6 ± 21.8 years) attendances were identified with an estimated HEECS annual new attendance rate of 31.0 per 1,000 population. Significantly more females (53%) than males (47%) attended HEECS (p < 0.001). Female attendances were 13% higher in those ≥50 years of age. Weekends were associated with a significant reduction in attendances compared to weekdays (χ² = 6.94, p < 0.001). Among weekdays, Mondays and Fridays were associated with significantly higher attendances compared with midweek (χ² = 2.20, p = 0.032). Presenting pathologies involving the external eye, cornea and conjunctiva accounted for 28.6% of the caseload.ConclusionThis is the largest multicentre study assessing attendance patterns in HEECS in England. We have, for the first time, observed a “weekend effect” in relation to attendance to HEECS. Differences in health-seeking behaviour and lack of awareness of HEECS weekend services may be partly attributed to the differences observed. Our findings, along with the type of presentations, have the potential to guide commissioners with future planning of HEECS.Subject terms: Epidemiology, Epidemiology     

Incongruent Expression of Brain-Derived Neurotrophic Factor and Cortisol in Schizophrenia: Results from a Randomized Controlled Trial of Laughter Intervention

ObjectiveSchizophrenia has been associated with dysfunction of the hypothalamic-pituitary-adrenal axis. Furthermore, alterations in neurotrophic factors might contribute to the pathogenesis of schizophrenia. We aimed to evaluate the effects of a simulated laughter intervention on the levels of cortisol and BDNF and to determine whether the effects associated with simulated laughter could be sustained after discontinuation of the intervention.MethodsIn this randomized controlled study, patients with schizophrenia according to DSM-IV clinical criteria were randomly assigned to receive either 8-week-long simulated laughter intervention (n=32) or treatment-as-usual group (control group, n=27). The serum levels of BDNF and cortisol were measured at baseline, week 8, and four weeks after discontinuation (week 12) of the intervention program. ResultsAfter an 8-week simulated laughter intervention, the laughter group had significantly higher levels of BDNF; however, four weeks after discontinuation of the intervention, the levels of BDNF significantly dropped. Interestingly, the levels of cortisol did not change significantly at week 8, but they were significantly elevated at week 12. The levels of BDNF and cortisol in the control group did not change significantly between week 0 and week 8. ConclusionThese findings suggest that the simulated laughter intervention has an early effect on neurogenesis with a significant delayed effect on stress regulation in subjects with schizophrenia.     

Severity of Daytime Sleepiness and Parkinsonian-Like Symptoms in Korean Adults Aged 50–64 Years

Background and PurposeWhile excessive daytime sleepiness can predate Parkinson’s disease in late-life, its association with parkinsonian-like (P-L) symptoms in middle age are unknown. Since neurodegeneration can appear decades before a diagnosis of Parkinson’s disease, identifying clinical features associated with this early progression is important. The purpose of this study was to determine the association of daytime sleepiness with P-L symptoms in a population-based sample of middle-aged Korean adults.MethodsDuring 2013 and 2014, daytime sleepiness and P-L symptoms were assessed in 2,063 males and females aged 50–64 years who were participating in the Korean Genome and Epidemiology Study. The severity of daytime sleepiness was quantified by the score on the Epworth Sleepiness Scale (ESS). Self-reported P-L symptoms included nine motor disorders commonly associated with Parkinson’s disease. Participants with parkinsonism and related conditions are excluded.ResultsThe prevalence of excessive daytime sleepiness (ESS score >10) was 7.0%. The frequencies of P-L symptoms ranged from 0.5% (for “trouble buttoning buttons”) to 18.4% (for “handwriting smaller than it once was”). After adjustment for covariates and multiple testing, the relative odds of P-L symptoms comparing the 80th and 20th percentiles of ESS scores was 1.6 (p=0.001) for “voice is softer than it once was,” 2.1 (p<0.001) for “balance when walking is poor,” and 1.5 (p=0.002) for “loss of facial expression.” The prevalence of excessive daytime sleepiness increased from 6.3% to 19.8% when the number of symptoms increased from zero to three (p=0.004).ConclusionsIn Korean adults aged 50–64 years, daytime sleepiness is significantly associated with P-L symptoms. Whether coexisting daytime sleepiness and P-L symptoms predate extrapyramidal and other impairments in later life warrants further investigation.     

The −22c/t polymorphism in presenilin 1 gene is not connected with late-onset and early-onset familial Alzheimer’s disease in Poland

Summary. The –22c/t polymorphism in the promoter of the presenilin 1 gene is associated with increased risk for Alzheimers disease (AD) in some populations. It was shown that –22c allele is connected with two-fold decrease in promoter activity. We studied the impact of the polymorphism in groups of Polish late-onset and early-onset AD patients. Our results suggest that –22c/t polymorphism is not connected with AD in Polish population. The –22t allele showed a high degree of linkage disequilibrium with –2797 insertion of 13bp. An additional –2923g/t polymorphism is also not connected with –22c/t and is not a risk factor for AD.     

Ordering Behavior of Layered Silicate Nanocomposites with a Cylindrical Triblock Copolymer

Summary: The ordering behavior of the nanocomposites of organically modified montmorillonite (OMMT) with a cylindrical triblock copolymer of polystyrene‐block‐poly(ethylene‐co‐butylene)‐block‐polystyrene (SEBS) has been investigated by temperature‐resolved small‐angle X‐ray scattering (SAXS) and rheometry. X‐Ray diffraction (XRD) confirms that the polymer chains are successfully intercalated with the interlayer gallery of the silicates. The data obtained from the SAXS and rheological measurements show that the addition of OMMT leads to a change in the microphase separation behavior of SEBS in the nanocomposites. The molecular interaction between OMMT and the polystyrene (PS) chains of SEBS decreases the structural perfection of the self‐assembling, phase‐separated domain structure of the nanocomposites. Rheological data exhibit that the order‐order (T_OOT) and order‐disorder transitions (T_ODT) of the SEBS/OMMT nanocomposites decrease with the addition of OMMT. The highest elongation at break is obtained at approximately 2% OMMT and its further addition to the mixture leads to decreases in tensile strength and elongation.

The change in the storage modulus (G′) of a) SEBS, b) S98M2, c) S95M5, and d) S90M10, as a function of temperature in the range of 150 ≤ T (°C) ≤ 260.     

Effects of butylated hydroxyanisole on the development and functions of reproductive system in rats

Butylated hydroxyanisol (BHA) is a widely used antioxidant for long preservation of food products, cosmetics and pharmaceuticals. Although BHA is generally recognized as safe, it is classified as a suspected endocrine-disrupting compound. We investigated the effects of BHA on reproductive function and development by the treatment of mature male and female SD rats (F0) through pre-gestation, gestation and lactation period and of their offspring (F1) until 13 weeks old via gavage with BHA 0 (corn oil, vehicle control), 10, 100 and 500 mg/kg bw/day. Organ weights of liver, adrenal gland and thyroid gland of F0 rats were increased by BHA 500 mg/kg but those of spleen and ventral prostate were decreased without significant difference in terminal body weight. Reduced serum testosterone and thyroxine (T4) were observed with dose-dependent manner in F0 male rats. Mating rate was decreased and cohabitation duration for conception was longer without differences in the number, motility and morphology of sperm by BHA 500 mg/kg. Body weight of F1 offspring was significantly decreased with change of relative weight of liver and brain by BHA 500 mg/kg at PND21. Sexual maturation indicated by vaginal opening and preputial separation was delayed by BHA 500 mg/kg. The weights of liver and adrenal gland were increased while those of spleen, vagina, testes and ventral prostate were decreased in F1 rats exposed to BHA 100 or 500 mg/kg for 13 weeks. Also, BHA 500 mg/kg reduced the velocity of sperm motion and number with smaller-sized sperm head in F1 male rats and slightly shortened estrous cycle length with higher frequency of estrus and lower frequency of diestrus stages in F1 female rats. Lower serum T4 and testosterone contents with higher serum cholesterol levels were also observed by BHA 500 mg/kg. Increased follicular cell height, and exfoliated and vacuolated follicular epithelial cells were observed in thyroids of F1 female and males rats exposed to BHA 500 mg/kg. This study elucidates that high dose of BHA induce weak dysfunction and underdevelopment of reproductive system of male and female rats with the change of T4 and testosterone levels, sex organ weights and sexual maturation and histological lesions of thyroid gland.     

Modified Split‐Cast Technique: A New,Timesaving Clinical Remount Technique

Interocclusal discrepancies can be eliminated by a clinical remount procedure, but most practitioners avoid it because of the time involved. This article introduces a new timesaving method, the modified split‐cast technique. It uses a semi‐adjustable articulator, tin foil as plaster separator, and an addition‐type, silicone bite‐registration material. The technician does most of the remounting procedures before the denture delivery appointment, so the dentist spends very little time chairside to complete the clinical remount procedure. Compared with the conventional and two other remounting techniques, the new technique is faster and easier to manipulate.