Behavior of steel reinforced concrete panels subjected to direct tension

Cracking of massive concrete structures like offshore and nuclear power plants structures is an important issue in designing and maintaining such structures. The low tensile strength of concrete can destroy the structural aesthetics and expose steel reinforcements to severe environmental conditions, leading to corrosion of reinforcement and other deterioration. -- The present research investigation ultimately aims to investigate the general behavior of steel-reinforced normal- and high-strength concrete panels subjected to uniaxial and biaxial direct tension loading taking into consideration the effect of the set of parameters that have the most significant effect on the cracking response. This investigation includes experimental, theoretical, and numerical modeling phases for the cracking response. -- The experimental study incorporates the effect of some important parameters such as the concrete strength, bar diameter, bar spacing, concrete cover, and reinforcement ratio on the cracking response of concrete panels. To conduct the current experimental investigation, a special test setup was designed and fabricated. The loading system was equipped to make it possible to simultaneously apply loads in both directions. Results of the experimental work will be presented in terms of cracking behavior (cracking load, crack spacing, crack width, and crack pattern and the mode of failure), stresses and strains in concrete and steel reinforcement before and after cracking. -- Compared with NSC panels, HSC panels showed lower strains and greater tension stiffening response at a given load level thanks to the corresponding improvement of the bond between the reinforcing steel bars and the high strength concrete matrix. The panels tested under biaxial loading conditions showed lower concrete tensile strength and tension stiffening response, compared with the panels subjected to uniaxial loading conditions. This reduction in the tensile strength of concrete panels subjected to biaxial loading was found to be equal to 5% - 15%. The reduction of the tension stiffening contribution of concrete between cracks due to applying the axial into biaxial direction became more significant as the reinforcing bar diameter was increased. -- An analytical study was conducted to study the bond characteristics between concrete and steel reinforcing bars. Also, a practical and new analytical model, which is capable of predicting the crack spacing of orthogonally reinforced concrete plate panels, was developed. Afterwards, this study developed a model for evaluating crack widths for thick reinforced concrete plates subjected to in-plane axial loading. The calculation procedure was supported by an evaluation of existing test data. -- Finally, the nonlinear analysis of reinforced concrete plates using the damage plasticity model was performed. The tension stiffening model developed in this study was implemented to simulate the cracking response of the concrete. The numerical results show reasonable accuracy in predicting the behavior of steel-reinforced concrete panels

The role of liquid ink transport in the direct placement of quantum dot emitters onto sub-micrometer antennas by dip-pen nanolithography

Dip‐pen nanolithography (DPN) is used to precisely position core/thick‐shell (“giant”) quantum dots (gQDs; ≥10 nm in diameter) exclusively on top of silicon nanodisk antennas (≈500 nm diameter pillars with a height of ≈200 nm), resulting in periodic arrays of hybrid nanostructures and demonstrating a facile integration strategy toward next‐generation quantum light sources. A three‐step reading‐inking‐writing approach is employed, where atomic force microscopy (AFM) images of the pre‐patterned substrate topography are used as maps to direct accurate placement of nanocrystals. The DPN “ink” comprises gQDs suspended in a non‐aqueous carrier solvent, o‐dichlorobenzene. Systematic analyses of factors influencing deposition rate for this non‐conventional DPN ink are described for flat substrates and used to establish the conditions required to achieve small (sub‐500 nm) feature sizes, namely: dwell time, ink‐substrate contact angle and ink volume. Finally, it is shown that the rate of solvent transport controls the feature size in which gQDs are found on the substrate, but also that the number and consistency of nanocrystals deposited depends on the stability of the gQD suspension. Overall, the results lay the groundwork for expanded use of nanocrystal liquid inks and DPN for fabrication of multi‐component nanostructures that are challenging to create using traditional lithographic techniques.F.D. and J.W. contributed equally to this work. F.D. was supported by postdoctoral funding of the Center for Integrated Nanotechnologies (CINT), an Office of Science (OS) Nanoscale Science Research Center (NSRC) and User Facility operated for the U.S. Department of Energy (DOE) by Los Alamos National Laboratory (LANL; Contract No. DE-AC52-06NA25396) and Sandia National Laboratories (Contract No. DE-NA-0003525), and the work was performed in large part at CINT and contributed to CINT User Project, C2013B0048. J.W., P.A.S., S.M., M.T., and J.A.H. acknowledge LANL Directed Research and Development Funds. C.J.S. is a CINT-funded technical specialist. M.R.B. was funded by an LANL Director's Postdoctoral Fellowship, and A.M.D. by a Single Investigator Small Group Research Grant (2009LANL1096), Division of Materials Science and Engineering (MSE), Office of Basic Energy Sciences (OBES), OS, DOE. Los Alamos National Laboratory, an affirmative action equal opportunity employer, is operated by Los Alamos National Security, LLC, for the National Nuclear Security Administration of the DOE under Contract No. DE-AC52-06NA25396. (Center for Integrated Nanotechnologies (CINT), an Office of Science (OS) Nanoscale Science Research Center (NSRC); DE-AC52-06NA25396 - U.S. Department of Energy (DOE); DE-NA-0003525 - U.S. Department of Energy (DOE); C2013B0048 - CINT User Project; LANL Directed Research and Development Funds; CINT; LANL Director's Postdoctoral Fellowship; 2009LANL1096 - Single Investigator Small Group Research Grant, Division of Materials Science and Engineering (MSE), Office of Basic Energy Sciences (OBES), OS, DOE; DE-AC52-06NA25396 - National Nuclear Security Administration of the DOE)Accepted manuscrip

Impact of opioid-free analgesia on pain severity and patient satisfaction after discharge from surgery: multispecialty, prospective cohort study in 25 countries

Background: Balancing opioid stewardship and the need for adequate analgesia following discharge after surgery is challenging. This study aimed to compare the outcomes for patients discharged with opioid versus opioid-free analgesia after common surgical procedures.Methods: This international, multicentre, prospective cohort study collected data from patients undergoing common acute and elective general surgical, urological, gynaecological, and orthopaedic procedures. The primary outcomes were patient-reported time in severe pain measured on a numerical analogue scale from 0 to 100% and patient-reported satisfaction with pain relief during the first week following discharge. Data were collected by in-hospital chart review and patient telephone interview 1 week after discharge.Results: The study recruited 4273 patients from 144 centres in 25 countries; 1311 patients (30.7%) were prescribed opioid analgesia at discharge. Patients reported being in severe pain for 10 (i.q.r. 1-30)% of the first week after discharge and rated satisfaction with analgesia as 90 (i.q.r. 80-100) of 100. After adjustment for confounders, opioid analgesia on discharge was independently associated with increased pain severity (risk ratio 1.52, 95% c.i. 1.31 to 1.76; P < 0.001) and re-presentation to healthcare providers owing to side-effects of medication (OR 2.38, 95% c.i. 1.36 to 4.17; P = 0.004), but not with satisfaction with analgesia (beta coefficient 0.92, 95% c.i. -1.52 to 3.36; P = 0.468) compared with opioid-free analgesia. Although opioid prescribing varied greatly between high-income and low- and middle-income countries, patient-reported outcomes did not.Conclusion: Opioid analgesia prescription on surgical discharge is associated with a higher risk of re-presentation owing to side-effects of medication and increased patient-reported pain, but not with changes in patient-reported satisfaction. Opioid-free discharge analgesia should be adopted routinely

The evolving SARS-CoV-2 epidemic in Africa: Insights from rapidly expanding genomic surveillance

INTRODUCTION Investment in Africa over the past year with regard to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) sequencing has led to a massive increase in the number of sequences, which, to date, exceeds 100,000 sequences generated to track the pandemic on the continent. These sequences have profoundly affected how public health officials in Africa have navigated the COVID-19 pandemic. RATIONALE We demonstrate how the first 100,000 SARS-CoV-2 sequences from Africa have helped monitor the epidemic on the continent, how genomic surveillance expanded over the course of the pandemic, and how we adapted our sequencing methods to deal with an evolving virus. Finally, we also examine how viral lineages have spread across the continent in a phylogeographic framework to gain insights into the underlying temporal and spatial transmission dynamics for several variants of concern (VOCs). RESULTS Our results indicate that the number of countries in Africa that can sequence the virus within their own borders is growing and that this is coupled with a shorter turnaround time from the time of sampling to sequence submission. Ongoing evolution necessitated the continual updating of primer sets, and, as a result, eight primer sets were designed in tandem with viral evolution and used to ensure effective sequencing of the virus. The pandemic unfolded through multiple waves of infection that were each driven by distinct genetic lineages, with B.1-like ancestral strains associated with the first pandemic wave of infections in 2020. Successive waves on the continent were fueled by different VOCs, with Alpha and Beta cocirculating in distinct spatial patterns during the second wave and Delta and Omicron affecting the whole continent during the third and fourth waves, respectively. Phylogeographic reconstruction points toward distinct differences in viral importation and exportation patterns associated with the Alpha, Beta, Delta, and Omicron variants and subvariants, when considering both Africa versus the rest of the world and viral dissemination within the continent. Our epidemiological and phylogenetic inferences therefore underscore the heterogeneous nature of the pandemic on the continent and highlight key insights and challenges, for instance, recognizing the limitations of low testing proportions. We also highlight the early warning capacity that genomic surveillance in Africa has had for the rest of the world with the detection of new lineages and variants, the most recent being the characterization of various Omicron subvariants. CONCLUSION Sustained investment for diagnostics and genomic surveillance in Africa is needed as the virus continues to evolve. This is important not only to help combat SARS-CoV-2 on the continent but also because it can be used as a platform to help address the many emerging and reemerging infectious disease threats in Africa. In particular, capacity building for local sequencing within countries or within the continent should be prioritized because this is generally associated with shorter turnaround times, providing the most benefit to local public health authorities tasked with pandemic response and mitigation and allowing for the fastest reaction to localized outbreaks. These investments are crucial for pandemic preparedness and response and will serve the health of the continent well into the 21st century

Precision additive nanofabrication: the role of liquid ink transport in the direct placement of quantum dot emitters onto sub-micrometer antennas by dip-pen nanolithography (Small 31/2018)

Back cover graphic.In article number 1801503 , Jennifer A. Hollingsworth and co‐workers demonstrate an advance in nanofabrication using dip‐pen nanolithography (DPN) to directly place nanocrystal quantum dots onto a three‐dimensional nanostructured optical antenna. The results lay the groundwork for the expanded use of DPN and other scanning probe technologies for the additive preparation of functional multi‐component systems and devices at the nanoscale.Published versio