A Comparative Study on the Flexural Behaviour of Rubberized and Hybrid Rubberized Reinforced Concrete Beams

This paper aims to investigate the flexural behaviour of the rubberized and hybrid rubberized reinforced concrete beams. A total of fourteen beams, 150×200 mm in cross-section with 1000 mm in length, were subject to a laboratory test over an effective span of 900 mm. The sand river aggregate was replaced by 10%, 12.5%, and 15% of crumb rubber (volume).   The hybrid structure contained two double layers: 1) rubberized reinforcement concrete at the top layer of the beam and 2) reinforcement concrete at the bottom layer of the concrete beam. The static responses by the flexural test of all the beams were evaluated in terms of their fresh properties, failure patterns, total energy, flexural strength, stiffness, and ultimate deflection, modulus of rupture, strain capacity, and ductility index. The results showed that there were improvements when the hybrid beams were used in most cases such as failure pattern, ultimate load, stiffness, modulus of rupture, and stress. The rubberized concrete beams showed improvements in the strain capacity as illustrated in strain gauges and stress-strain curves, toughness, ultimate deflection, and ductility index. The findings of the study revealed an improved performance with the use of the hybrid beams. This has resulted in the implementation of innovative civil engineering applications in the engineering sustainable structures

AlN overgrowth of nano-pillar-patterned sapphire with different offcut angle by metalorganic vapor phase epitaxy

We present overgrowth of nano-patterned sapphire with different offcut angles by metalorganic vapor phase epitaxy. Hexagonal arrays of nano-pillars were prepared via Displacement Talbot Lithography and dry-etching. 6.6 µm crack-free and fully coalesced AlN was grown on such substrates. Extended defect analysis comparing X-ray diffraction, electron channeling contrast imaging and selective defect etching revealed a threading dislocation density of about 109 cm−2. However, for c-plane sapphire offcut of 0.2° towards m direction the AlN surface shows step bunches with a height of 10 nm. The detrimental impact of these step bunches on subsequently grown AlGaN multi-quantum-wells is investigated by cathodoluminescence and transmission electron microscopy. By reducing the sapphire offcut to 0.1° the formation of step bunches is successfully suppressed. On top of such a sample an AlGaN-based UVC LED heterostructure is realized emitting at 265 nm and showing an emission power of 0.81 mW at 20 mA (corresponds to an external quantum efficiency of 0.86%)

AlN overgrowth of nano-pillar-patterned sapphire with different offcut angle by metalorganic vapor phase epitaxy

We present overgrowth of nano-patterned sapphire with different offcut angles by metalorganic vapor phase epitaxy. Hexagonal arrays of nano-pillars were prepared via Displacement Talbot Lithography and dry-etching. 6.6 µm crack-free and fully coalesced AlN was grown on such substrates. Extended defect analysis comparing X-ray diffraction, electron channeling contrast imaging and selective defect etching revealed a threading dislocation density of about 109 cm-2. However, for c-plane sapphire offcut of 0.2° towards m direction the AlN surface shows step bunches with a height of 10 nm. The detrimental impact of these step bunches on subsequently grown AlGaN multi-quantum-wells is investigated by cathodoluminescence and transmission electron microscopy. By reducing the sapphire offcut to 0.1° the formation of step bunches is successfully suppressed. On top of such a sample an AlGaN-based UVC LED heterostructure is realized emitting at 265 nm and showing an emission power of 0.81 mW at 20 mA (corresponds to an external quantum efficiency of 0.86 %)

Structural and luminescence imaging and characterisation of semiconductors in the scanning electron microscope

The scanning electron microscopy techniques of electron backscatter diffraction (EBSD), electron channelling contrast imaging (ECCI) and hyperspectral cathodoluminescence imaging (CL) provide complementary information on the structural and luminescence properties of materials rapidly and non-destructively, with a spatial resolution of tens of nanometres. EBSD provides crystal orientation, crystal phase and strain analysis, whilst ECCI is used to determine the planar distribution of extended defects over a large area of a given sample. CL reveals the influence of crystal structure, composition and strain on intrinsic luminescence and/or reveals defect-related luminescence. Dark features are also observed in CL images where carrier recombination at defects is non-radiative. The combination of these techniques is a powerful approach to clarifying the role of crystallography and extended defects on a materials' light emission properties. Here we describe the EBSD, ECCI and CL techniques and illustrate their use for investigating the structural and light emitting properties of UV-emitting nitride semiconductor structures. We discuss our investigations of the type, density and distribution of defects in GaN, AlN and AlGaN thin films and also discuss the determination of the polarity of GaN nanowires

Scanning electron microscope as a flexible tool for investigating the properties of UV-emitting nitride semiconductor thin films

In this paper we describe the scanning electron microscopy techniques of electron backscatter diffraction, electron channeling contrast imaging, wavelength dispersive X-ray spectroscopy, and cathodoluminescence hyperspectral imaging. We present our recent results on the use of these non-destructive techniques to obtain information on the topography, crystal misorientation, defect distributions, composition, doping, and light emission from a range of UV-emitting nitride semiconductor structures. We aim to illustrate the developing capability of each of these techniques for understanding the properties of UV-emitting nitride semiconductors, and the benefits were appropriate, in combining the techniques

Expanding the genetic heterogeneity of intellectual disability

Intellectual disability (ID) is a common morbid condition with a wide range of etiologies. The list of monogenic forms of ID has increased rapidly in recent years thanks to the implementation of genomic sequencing techniques. In this study, we describe the phenotypic and genetic findings of 68 families (105 patients) all with novel ID-related variants. In addition to established ID genes, including ones for which we describe unusual mutational mechanism, some of these variants represent the first confirmatory disease-gene links following previous reports (TRAK1, GTF3C3, SPTBN4 and NKX6-2), some of which were based on single families. Furthermore, we describe novel variants in 14 genes that we propose as novel candidates (ANKHD1, ASTN2, ATP13A1, FMO4, MADD, MFSD11, NCKAP1, NFASC, PCDHGA10, PPP1R21, SLC12A2, SLK, STK32C and ZFAT). We highlight MADD and PCDHGA10 as particularly compelling candidates in which we identified biallelic likely deleterious variants in two independent ID families each. We also highlight NCKAP1 as another compelling candidate in a large family with autosomal dominant mild intellectual disability that fully segregates with a heterozygous truncating variant. The candidacy of NCKAP1 is further supported by its biological function, and our demonstration of relevant expression in human brain. Our study expands the locus and allelic heterogeneity of ID and demonstrates the power of positional mapping to reveal unusual mutational mechanisms

Advances in electron channelling contrast imaging and electron backscatter diffraction for imaging and analysis of structural defects in the scanning electron microscope

In this article we describe the scanning electron microscopy (SEM) techniques of electron channelling contrast imaging and electron backscatter diffraction. These techniques provide information on crystal structure, crystal misorientation, grain boundaries, strain and structural defects on length scales from tens of nanometres to tens of micrometres. Here we report on the imaging and analysis of dislocations and sub-grains in nitride semiconductor thin films (GaN and AlN) and tungsten carbide-cobalt (WC-Co) hard metals. Our aim is to illustrate the capability of these techniques for investigating structural defects in the SEM and the benefits of combining these diffraction-based imaging techniques

Effects of chronic inhalation of electronic cigarettes containing nicotine on glial glutamate transporters and α-7 nicotinic acetylcholine receptor in female CD-1 mice

Alteration in glutamate neurotransmission has been found to mediate the development of drug dependence, including nicotine. We and others, through using western blotting, have reported that exposure to drugs of abuse reduced the expression of glutamate transporter-1 (GLT-1) as well as cystine/glutamate antiporter (xCT), which consequently increased extracellular glutamate concentrations in the mesocorticolimbic area. However, our previous studies did not reveal any changes in glutamate/aspartate transporter (GLAST) following exposure to drugs of abuse. In the present study, for the first time, we investigated the effect of chronic exposure to electronic (e)-cigarette vapor containing nicotine, for one hour daily for six months, on GLT-1, xCT, and GLAST expression in frontal cortex (FC), striatum (STR), and hippocampus (HIP) in outbred female CD1 mice. In this study, we also investigated the expression of alpha-7 nicotinic acetylcholine receptor (α-7 nAChR), a major pre-synaptic nicotinic receptor in the glutamatergic neurons, which regulates glutamate release. We found that inhalation of e-cigarette vapor for six months increased α-7 nAChR expression in both FC and STR, but not in the HIP. In addition, chronic e-cigarette exposure reduced GLT-1 expression only in STR. Moreover, e-cigarette vapor inhalation induced downregulation of xCT in both the STR and HIP. We did not find any significant changes in GLAST expression in any brain region. Finally, using liquid chromatography-tandem mass spectrometry (LC-MS/MS) techniques, we detected high concentrations of nicotine and cotinine, a major metabolite of nicotine, in the FC tissues of e-cigarette exposed mice. These data provide novel evidence about the effects of chronic nicotine inhalation on the expression of key glial glutamate transporters as well as α-7 nAChR. Our work may suggest that nicotine exposure via chronic inhalation of e-cigarette vapor may be mediated in part by alterations in the glutamatergic system

Association between preoperative statin therapy and postoperative infectious complications in patients undergoing cardiac surgery: a systematic review and meta-analysis.

Infectious complications of cardiac surgery are often severe and life threatening. Statins having both immunomodulatory and anti-inflammatory effects were intuitively thought to influence the development of postsurgical infections. We sought to systematically examine whether any association exists between statin use and risk of infectious complications in patients undergoing cardiac surgery. We searched Ovid MEDLINE, Ovid EMBASE, Thomson Scientific Web of Science, and Elsevier Scopus from inception through February 2011 for comparative studies examining the association between statin use and risk of postoperative infections in patients undergoing cardiac surgery. We contacted a study's author for missing information. We conducted a random-effects meta-analysis of individual studies' odds ratios (adjusted for potential confounders). We identified 6 cohort studies for inclusion, 3 of which were conducted in Canada and 3 of which were conducted in the United States. Four were single-center studies, and 2 were population based. Exposure ascertainment was based on a review of admission medication list or prescription databases. Infectious outcomes were heterogeneous and included surgical site infections within 30 days, serious infections (sepsis), or any other postoperative infection. Statin use in the preoperative period was associated with a trend toward reduction in the incidence of postoperative infections in patients who underwent cardiac surgery (odds ratio, 0.81 [95% confidence interval, 0.64–1.01]; P = .06; I2 = 75%). Heterogeneity was explained by country effect. Studies performed in Canada showed weaker associations than studies performed in the United States. This difference could not be attributed to study quality alone. We did not find good evidence to support an association between statin use and postoperative infectious complications. However, the trend toward statistical significance for this association indicates that further investigation is warranted

Substance Use and Misuse among Adults with Chronic Obstructive Pulmonary Disease in the United States, 2015–2019: Prevalence, Association, and Moderation

Background: Despite the advancements in chronic obstructive pulmonary disease (COPD) treatment, complications related to COPD exacerbation remain challenging. One associated factor is substance use/misuse among adults with COPD. Fewer studies, however, examined the prevalence and association between COPD and substance use and misuse. In addition, limited knowledge existed about the moderation effects of serious psychological distress and gender among adults with COPD and substance use/misuse. We aimed, therefore, to measure such prevalence, association, and moderation from nationally representative samples in the United States. Method: Data were drawn from the 2015–2019 National Survey on Drug Use and Health. Weighted logistic regressions were used to measure the associations of last-month tobacco (cigarettes, cigars, pipe, and smokeless tobacco products), other licit and illicit substance use (alcohol, marijuana, cocaine, crack, heroin, hallucinogens, and inhalants), and substance misuse (pain relievers, tranquilizers, stimulants, and sedatives) among adults with COPD. Serious psychological distress and gender were tested as moderators in the association between COPD and substance use/misuse. Results: The findings revealed that adults with COPD [Weighted N = 53,115,718) revealed greater odds of cigarettes [adjusted odds ratio (aOR) = 2.48 (95%CI = 1.80–3.42)) and smokeless tobacco (aOR = 3.65 (95%CI = 1.75–7.65)). However, they were less likely to use alcohol (aOR = 0.61 (95%CI = 0.45–0.84)). Adults with COPD who had serious psychological distress were more likely to use pipe tobacco and alcohol; however, they were less likely to use hallucinogens and inhalants. Finally, males compared to females with COPD were less likely to use smokeless tobacco. Conclusion: Adults with COPD in the United States were more likely to use tobacco products and less likely to use alcohol. In addition, serious psychological distress and gender were moderators in associations between COPD and substance use but not in substance misuse. Future studies should longitudinally assess the factors that may contribute to the initiation and progression of substance use and misuse among adults with COPD