Impact Strength of Preplaced Aggregate Concrete Comprising Glass Fibre Mesh and Steel Fibres: Experiments and Modeling

Concrete is the most widely used and most affordable construction material. The structural damage that concrete cracks and fractures may cause can be severe. These concerns have lately been alleviated by new developments in fibre concretes. Recent advancements in fibrous concrete and its evolution have been rapidly drawing researchers’ attentions worldwide, which motivates the development of a new type of composite with superior impact resistance. Preplaced aggregate fibrous concrete (PAFC) is a revolutionary composite comprising a higher dosage of fibres. It has outstanding impact resistance that surpasses those of traditional fibrous concrete. The impact behaviour of PAFC in addition to glass fibre mesh (GFM) has not been investigated thoroughly. To fill this research gap, this study investigates the impact performance of three-layered PAFC comprising steel fibres and GFM insertion. Eight different mixtures were prepared and can be divided into two groups. In the first group, specimens were made with 4% fibres and two single, double and triple layers of GFM insertion between the three-layered concrete. The second group of specimens was reinforced with 5, 2 and 5% steel fibres at the top, middle and bottom layers, respectively. However, the GFM insertion scheme for the second group was the same as the first. Rectangular specimens of size 500 × 100 × 100 mm were cast and tested against drop weight impact. The parameters studied were cracking impact numbers, failure impact number, ductility index and failure patterns. In addition, an analytical model was used to evaluate the impact failure energies. Results indicate that the combined action of steel fibre and GFM exhibited an excellent impact resistance. Increasing the number of GFM insertions between the specimen layer led to increased impact strength. The dose of the fibres utilized in the outer layer of the PAFC was increased, resulting in the material having a higher impact resistance. The cracking impact numbers improved from 28 to 40%, and failure impact numbers ranged from 58.8 to 92.2% when the GFM insertion numbers increased from one to three.     

Predictors of all‐cause mortality among patients hospitalized with influenza,respiratory syncytial virus,or SARS‐CoV‐2

BackgroundShared and divergent predictors of clinical severity across respiratory viruses may support clinical and community responses in the context of a novel respiratory pathogen.MethodsWe conducted a retrospective cohort study to identify predictors of 30‐day all‐cause mortality following hospitalization with influenza (N = 45,749; 2010‐09 to 2019‐05), respiratory syncytial virus (RSV; N = 24 345; 2010‐09 to 2019‐04), or severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2; N = 8988; 2020‐03 to 2020‐12; pre‐vaccine) using population‐based health administrative data from Ontario, Canada. Multivariable modified Poisson regression was used to assess associations between potential predictors and mortality. We compared the direction, magnitude, and confidence intervals of risk ratios to identify shared and divergent predictors of mortality.ResultsA total of 3186 (7.0%), 697 (2.9%), and 1880 (20.9%) patients died within 30 days of hospital admission with influenza, RSV, and SARS‐CoV‐2, respectively. Shared predictors of increased mortality included older age, male sex, residence in a long‐term care home, and chronic kidney disease. Positive associations between age and mortality were largest for patients with SARS‐CoV‐2. Few comorbidities were associated with mortality among patients with SARS‐CoV‐2 as compared with those with influenza or RSV.ConclusionsOur findings may help identify patients at greatest risk of illness secondary to a respiratory virus, anticipate hospital resource needs, and prioritize local prevention and therapeutic strategies to communities with higher prevalence of risk factors.     

Spondyloarthropathy presenting at a young age: case report and review

The diagnosis of juvenile spondyloarthritis (JSA) is rarely entertained in young children who present with back and leg pain. We present a case of a 6-year-old male who presented with a 3-year history of severe back and leg pain and a positive Gower’s sign, and was given a presumed diagnosis of muscular dystrophy. Presenting serologic evaluation included a mildly elevated sedimentation rate and C-reactive protein (CRP). Computed tomography of the pelvis demonstrated large erosions affecting both sacro-iliac joints. Despite the unusually young age of this patient, ankylosing spondylitis seemed the most plausible diagnosis. Following rheumatological evaluation and treatment for JSA, he showed significant clinical improvement. His disease, however, has not entirely remitted with signs of enthesitis at the Achilles tendon and knees. We present this case to illustrate that JSA could account for symptoms at an early age and not considering it could lead to multiple medical visits and diagnoses. To our knowledge, based on a search of the World literature, this would appear to be the youngest case of JSA reported with demonstrable severe sacroiliitis. Presented at the 31st Annual members Meeting of the International Skeletal Society in Malta, September 2004.     

Influence of extremely low frequency magnetic fields on Ca2+ signaling and NMDA receptor functions in rat hippocampus

The nervous tissue of many vertebrates, including humans, can synthesize beta-alanyl-L-histidine (carnosine). The biological functions of carnosine are still open to question, although several theories supported by strong experimental data have been proposed. The objective of this study was to examine the effects of carnosine on neurotoxicity in differentiated rat pheochromocytoma (PC12) cells. Neurotoxicity was induced by N-methyl-D-aspartate (NMDA), which caused time- and concentration-dependent cell death as measured by MTT and LDH assays. Pretreatment with carnosine significantly prevented the neurotoxicity in a concentration-dependent manner. The protective effect of carnosine was antagonized by the H1 receptor antagonist pyrilamine, but not by the H2 receptor antagonist cimetidine. In addition, alpha-fluoromethylhistidine, a histidine decarboxylase inhibitor, slightly reversed the protective action of carnosine. These results indicate that carnosine can effectively protect against NMDA-induced necrosis in PC12 cells, and its protection may in part be due to the activation of the postsynaptic histamine H1 receptor. The study suggests that carnosine may be an endogenous protective factor and calls for its further study as a new anti-excitotoxic agent.     

Multi-chorionic pregnancies following single embryo transfer at the blastocyst stage: a case series and review of the literature

Objective

To report cases of in vitro fertilization-frozen embryo transfer (IVF-FET) with single blastocyst transfer resulting in di- or tri-chorionic pregnancies, and to review the literature on monozygotic, multi-chorionic pregnancies originating at the blastocyst stage.

Design

Retrospective case series and literature review.

Materials and methods

All in vitro fertilization cycles (fresh, frozen, autologous, and donor oocyte) performed between June 2012 and June 2017 at the University of California, San Francisco Center for Reproductive Health, were reviewed retrospectively. Cycles with cleavage-stage embryos or transfer of more than one blastocyst were excluded. Cycles were analyzed to determine if clinical pregnancy occurred with the presence of two or more gestational sacs noted on initial ultrasound. An in-depth chart review was performed with further exclusions applied that would lend credence to dizygosity rather than monozygosity such as fetal/neonatal sex discordance, fresh embryo transfer, and natural cycle FET (in which concomitant spontaneous pregnancy could have occurred). Demographic, clinical and IVF-FET cycle characteristics of the resulting patients were collected. Additionally, a review of the English language literature was performed (PUBMED, PMC) using the search words monozygotic twins, dichorionic diamniotic, in vitro fertilization, and single embryo transfer in order to identify cases of DC-DA monozygotic twinning from 1978 to 2017. Resulting articles were reviewed to eliminate all cases of dizygosity and day 3 embryo transfers. We obtained the following data from the literature search: basic patient demographics, type of fertilization, type and day of embryo transferred, number of embryos transferred, gestational ultrasound details, presence of any genetic testing if performed after delivery, and number of live births.

Result(s)

Two thousand four hundred thirty-four women underwent fresh or frozen single embryo transfer between June 2012 and June 2017 at the University of California, San Francisco Center for Reproductive Health. Of these, 11 women underwent a single blastocyst transfer with subsequent clinical pregnancies identified as multi-chorionic gestations. Four were in downregulated controlled FET cycles, in which concomitant spontaneous pregnancy could not have been possible. We then reviewed all cases of monozygotic dichorionic-diamniotic (DC-DA) splitting in IVF patients reported in the literature from 1978 to 2017. These eight cases demonstrate monozygotic splitting after the blastocyst stage, which challenges the existing dogma that only monochorionic twins can develop after day 3 post-fertilization.

Conclusion(s)

The accepted theory of monozygotic twinning resulting from the splitting of an embryo per a strict post-fertilization timing protocol must be re-examined with the advent of observed multi-chorionic pregnancies resulting from single blastocyst transfer in the context of IVF.

     

Vitamin K status of preterm infants with a prolonged prothrombin time

AIM: To investigate the vitamin K status of preterm infants who have a prolonged prothrombin time (PT) in the first month of life. METHODS: Measures of vitamin K status were assessed in 21 preterm infants who were found to have an abnormal PT, despite 0.2-0.5 mg vitamin K(1) prophylaxis at birth. RESULTS: All infants had normal or supraphysiological vitamin K(1) concentrations and undetectable or, in one infant, insignificant PIVKA-II, indicating adequate vitamin K status. CONCLUSION: In preterm infants born at <32 wk gestation who received > or = 0.2 mg vitamin K(1) after delivery, a prolonged PT in the first month of life is unlikely to be due to vitamin K deficiency.     

Cytolysis of neuraminidase-treated autochthonous lymphoid cells by autologous serum.

Rabbit lymph node cells treated with bacterial neuraminidase become susceptible to cytolysis by autologous antibody and complement. Cytolysis of cells can be prevented by absorbing out the antibodies, probably IgM antibodies, from the autologous serum using neuraminidase-treated autochthonous lymph node cells. The significance of this mechanism is discussed.