Effect of Cooling Conditions, Retrofitting on Strength of Concrete Subjected to Elevated Temperature

Concrete has a high degree of fire resistance at moderate temperatures. High temperatures, however, cause concrete to lose its stiffness and strength. The effects of cooling techniques and retrofitting on the strength of concrete exposed to high temperatures have not been synchronized in previous studies. This experimental research aims to evaluate the effect of cooling conditions and the effectiveness of retrofitting concrete subjected to elevated temperatures. Four types of concrete: M 20 normal concrete (NC); M 20 metakaolin concrete (MC); M 40 standard concrete (SC); and M 40 self-compacting concrete (SCC) are considered in this study. A total of 864 samples consisting of cube, beam, and cylinder specimens are subjected to sustained elevated temperatures of 400oC, 600oC, and 800oC for 2 hours rating. The weight and strength of half of the heat-damaged samples are assessed following natural air cooling (NAC) and water jet cooling (WJC). The remaining 50% of samples retrofitted with carbon fiber reinforced polymer (CFRP) are tested to evaluate the upgraded strength. The experimental findings demonstrate that water jet cooling (WJC) causes more strength degradation, and CFRP proves to be effective in restoring the strength of heat-deteriorated specimens. Overall, self-compacting concrete (SCC) has shown high resistance to elevated temperatures. Doi: 10.28991/CEJ-2023-09-07-013 Full Text: PD

Third-generation RNA-sequencing analysis : graph alignment and transcript assembly with long reads

The information contained in the genome of an organism, its DNA, is expressed through transcription of its genes to RNA, in quantities determined by many internal and external factors. As such, studying the gene expression can give valuable information for e.g. clinical diagnostics. A common analysis workflow of RNA-sequencing (RNA-seq) data consists of mapping the sequencing reads to a reference genome, followed by the transcript assembly and quantification based on these alignments. The advent of second-generation sequencing revolutionized the field by reducing the sequencing costs by 50,000-fold. Now another revolution is imminent with the third-generation sequencing platforms producing an order of magnitude higher read lengths. However, higher error rate, higher cost and lower throughput compared to the second-generation sequencing bring their own challenges. To compensate for the low throughput and high cost, hybrid approaches using both short second-generation and long third-generation reads have gathered recent interest. The first part of this thesis focuses on the analysis of short-read RNA-seq data. As short-read mapping is an already well-researched field, we focus on giving a literature review of the topic. For transcript assembly we propose a novel (at the time of the publication) approach of using minimum-cost flows to solve the problem of covering a graph created from the read alignments with a set of paths with the minimum cost, under some cost model. Various network-flow-based solutions were proposed in parallel to, as well as after, ours. The second part, where the main contributions of this thesis lie, focuses on the analysis of long-read RNA-seq data. The driving point of our research has been the Minimum Path Cover with Subpath Constraints (MPC-SC) model, where transcript assembly is modeled as a minimum path cover problem, with the addition that each of the chains of exons (subpath constraints) created from the long reads must be completely contained in a solution path. In addition to implementing this concept, we experimentally studied different approaches on how to find the exon chains in practice. The evaluated approaches included aligning the long reads to a graph created from short read alignments instead of the reference genome, which led to our final contribution: extending a co-linear chaining algorithm from between two sequences to between a sequence and a directed acyclic graph.Transkriptiossa organismin geenien mallin mukaan luodaan RNA-molekyyleja. Lukuisat tekijät, sekä solun sisäiset että ulkoiset, määrittävät mitä geenejä transkriptoidaan, ja missä määrin. Tämän prosessin tutkiminen antaa arvokasta tietoa esimerkiksi lääketieteelliseen diagnostiikkaan. Yksi yleisistä RNA-sekvensointidatan analyysitavoista koostuu kolmesta osasta: lukujaksojen (read sequences) linjaus referenssigenomiin, transkriptien kokoaminen, ja transkriptien ekspressiotasojen määrittäminen. Toisen sukupolven sekvensointiteknologian kehityksen myötä sekvensoinnin hinta laski huomattavasti, mikä salli RNA-sekvensointidatan käytön yhä useampaan tarkoitukseen. Nyt kolmannen sukupolven sekvensointiteknologiat tarjoavat kertaluokkaa pidempiä lukujaksoja, mikä laajentaa analysointimahdollisuuksia. Kuitenkin suurempi virhemäärä, korkeampi hinta ja pienempi määrä tuotettua dataa tuovat omat haasteensa. Toisen ja kolmannen sukupolven teknologioiden käyttäminen yhdessä, ns. hybridilähestymistapa, on tutkimussuunta joka on kerännyt paljon kiinnostusta viimeaikoina. Tämän tutkielman ensimmäinen osa keskittyy toisen sukupolven, eli ns. lyhyiden RNA-lukujaksojen (short read), analyysiin. Näiden lyhyiden lukujaksojen linjausta referenssigenomiin on tutkittu jo 2000-luvulla, joten tällä alueella keskitymme olemassaolevaan kirjallisuuteen. Transkriptien kokoamisen alalta esittelemme metodin, joka käyttää vähimmäiskustannusvirtauksen (minimum-cost flow) mallia. Vähimmäiskustannusvirtauksen mallissa lukujaksoista luotu verkko peitetään joukolla polkuja, joiden kustannus on pienin mahdollinen. Virtausmalleja on käytetty myös muiden tutkijoiden kehittämissä analyysityökaluissa. Tämän tutkielman suurin kontribuutio on toisessa osassa, joka keskittyy ns. pitkien RNA-lukujaksojen (long read) analysointiin. Tutkimuksemme lähtökohtana on ollut malli, jossa pienimmän polkupeitteen (Minimum Path Cover) ongelmaan lisätään alipolkurajoitus (subpath constraint). Jokainen alipolkurajoitus vastaa eksoniketjua (exon chain), jotka jokin pitkä lukujakso peittää, ja jokaisen alipolkurajoituksen täytyy sisältyä kokonaan johonkin polkupeitteen polkuun. Tämän konseptin toteuttamisen lisäksi testasimme kokeellisesti erilaisia lähestymistapoja eksoniketjujen löytämiseksi. Näihin testattaviin lähestymistapoihin kuului pitkien lukujaksojen linjaaminen suoraan lyhyistä lukujaksoista luotuun verkkoon referenssigenomin sijaan. Tämä lähestymistapa johti tämän tutkielman viimeiseen kontribuutioon: kolineaarisen ketjun (co-linear chaining) algoritmin yleistäminen kahden sekvenssin sijasta sekvenssiin ja suunnattuun syklittömään verkkoon

Evaluation of three lidar scanning strategies for turbulence measurements

Several errors occur when a traditional Doppler beam swinging (DBS) or velocity–azimuth display (VAD) strategy is used to measure turbulence with a lidar. To mitigate some of these errors, a scanning strategy was recently developed which employs six beam positions to independently estimate the <i>u</i>, <i>v</i>, and <i>w</i> velocity variances and covariances. In order to assess the ability of these different scanning techniques to measure turbulence, a Halo scanning lidar, WindCube v2 pulsed lidar, and ZephIR continuous wave lidar were deployed at field sites in Oklahoma and Colorado with collocated sonic anemometers.</br></br>Results indicate that the six-beam strategy mitigates some of the errors caused by VAD and DBS scans, but the strategy is strongly affected by errors in the variance measured at the different beam positions. The ZephIR and WindCube lidars overestimated horizontal variance values by over 60 % under unstable conditions as a result of variance contamination, where additional variance components contaminate the true value of the variance. A correction method was developed for the WindCube lidar that uses variance calculated from the vertical beam position to reduce variance contamination in the <i>u</i> and <i>v</i> variance components. The correction method reduced WindCube variance estimates by over 20 % at both the Oklahoma and Colorado sites under unstable conditions, when variance contamination is largest. This correction method can be easily applied to other lidars that contain a vertical beam position and is a promising method for accurately estimating turbulence with commercially available lidars

Effect of physiotherapy on single breath count and breath holding time in COVID-19 patients

Background: The novel Coronavirus is known to primarily affect the respiratory system and physiotherapy treatment is integral to combat this infection. However, the assessment of pulmonary function poses a difficult challenge considering the risk of spread of infection and sanitisation of the devices used. Single breath count (SBC) and breath holding time (BHT) can be thus adopted as bedside assessment tests for pulmonary function following physiotherapy treatment.Method: In this a retrospective observational study of 51 COVID-19 patients, mean age 51.7±14.56 years, on room air, admitted in the step-down units of a tertiary care hospital. Patients received standard physiotherapy treatment, within safe hemodynamic limits. Pre and post treatment session SBC was recorded in 32 patients and BHT in 19 patients. Three reading were noted and the best of three readings were used for analysis.Results: The paired t test was used to analyse SBC and BHT. Mean pre and post SBC was 18.25±8.96 and 23.31±9.96 respectively with a mean difference of 5.06 and p<0.0001. Mean pre and post BHT were 19.37 and 23.05 seconds respectively with a mean difference of 3.68 and p<0.0001.  Statistically significant difference in the pre and post treatment session SBC and BHT was observed, indicating a positive effect of physiotherapy treatment on pulmonary function.Conclusion: Physiotherapy treatment shows significant improvement in the pulmonary function in COVID-19 patients. SBC and BHT tests can be used as assessment and prognostic tools for pulmonary function in COVID-19 patients

Kinetically Decoupled Electrical and Structural Phase Transitions in VO2

Vanadium dioxide (VO2) has drawn significant attention for its near room temperature insulator to metal transition and associated structural phase transition. The underlying Physics behind the temperature induced insulator to metal and concomitant structural phase transition in VO2 is yet to be fully understood. We have investigated the kinetics of the above phase transition behaviors of VO2 with the help of resistivity measurements and Raman spectroscopy. Resistance thermal hysteresis scaling and relaxation measurements across the temperature induced insulator to metal transition reveal the unusual behaviour of this first-order phase transition, whereas Raman relaxation measurements show that the temperature induced structural phase transition in VO2 follows usual behaviour and is consistent with mean field prediction. At higher temperature sweeping rates decoupling of insulator to metal transition and structural phase transition have been confirmed. The observed anomalous first order phase transition behavior in VO2 is attributed to the unconventional quasi particle dynamics, i.e. significantly lowered electronic thermal conductivity across insulator to metal transition, which is confirmed by ultrafast optical pump-probe time domain thermoreflectance measurements.Comment: 25 pages, 8 figure

Multiple exciton generation in VO2

Multiple exciton generation (MEG) is a widely studied phenomenon in semiconductor nanocrystals and quantum dots, aimed at improving the energy conversion efficiency of solar cells. MEG is the process wherein incident photon energy is significantly larger than the band gap, and the resulting photoexcited carriers relax by generating additional electron-hole pairs, rather than decaying by heat dissipation. Here, we present an experimental demonstration of MEG in a prototype strongly correlated material, VO2, through photocurrent spectroscopy and ultrafast transient reflectivity measurements, both of which are considered the most prominent ways for detecting MEG in working devices. The key result of this paper is the observation of MEG at room temperature (in a correlated insulating phase of VO2), and the estimated threshold for MEG is 3Eg. We demonstrate an escalated photocurrent due to MEG in VO2, and quantum efficiency is found to exceed 100%. Our studies suggest that this phenomenon is a manifestation of expeditious impact ionization due to stronger electron correlations and could be exploited in a large number of strongly correlated materials.Comment: 6 pages, 5 figures, Physical Review

Transverse Electronic Transport through DNA Nucleotides with Functionalized Graphene Electrodes

Graphene nanogaps and nanopores show potential for the purpose of electrical DNA sequencing, in particular because single-base resolution appears to be readily achievable. Here, we evaluated from first principles the advantages of a nanogap setup with functionalized graphene edges. To this end, we employed density functional theory and the non-equilibrium Green's function method to investigate the transverse conductance properties of the four nucleotides occurring in DNA when located between the opposing functionalized graphene electrodes. In particular, we determined the electrical tunneling current variation as a function of the applied bias and the associated differential conductance at a voltage which appears suitable to distinguish between the four nucleotides. Intriguingly, we observe for one of the nucleotides a negative differential resistance effect.Comment: 19 pages, 7 figure

High electromechanical response in the non morphotropic phase boundary piezoelectric system PbTiO3-Bi(Zr1/2Ni1/2)O-3

There is a general perception that a large piezoelectric response in ferroelectric solid solutions requires a morphotropic/polymorphic phase boundary (MPB/PPB), i.e., a composition driven interferroelectric instability. This correlation has received theoretical support from models which emphasize field driven polarization rotation and/or interferroelectric transformations. Here, we show that the ferroelectric system ( 1 − x ) PbTi O 3 − ( x ) Bi ( Zr 1 / 2 Ni 1 / 2 ) O 3 (PT-BNZ), which shows d 33 ( ∼ 400 p C / N ) comparable to the conventional MPB/PPB systems, does not belong to this category. In the unpoled state the compositions of PT-BNZ showing large d 33 exhibit a coexistence of tetragonal and cubiclike (CL) phases on the global length scale. A careful examination of the domain strucures and global structures (both in the unpoled and poled states) revealed that the CL phase has no symptom of average rhombohedral distortion even on the local scale. The CL phase is rather a manifestation of tetragonal regions of short coherence length. Poling increases the coherence length irreversibly which manifests as poling induced CL → P 4 m m transformation on the global scale. PT-BNZ is therefore qualitatively different from the conventional MPB piezoelectrics. In the absence of the composition and temperature driven interferroelectric instability in this system, polarization rotation and interferroelectric transformation are no longer plausible mechanisms to explain the large electromechanical response. The large piezoelectricity is rather associated with the increased structural-polar heterogeneity due to domain miniaturization without the system undergoing a symmetry change. Our study proves that attainment of large piezoelectricity does not necessarily require interferroelectric instability (and hence morphotropic/polymorphic phase boundary) as a criterion

Erratum Ground state potential energy surfaces around selected atoms from resonant inelastic x ray scattering

Scientific Reports6 20054; doi 10.1038 srep20054; published online 29 January 2016; updated 30 June 2017The original HTML version of this Article listed an incorrect volume number. This has now been corrected in the HTML version; the PDF version was correct at the time of publicatio

Innate immunodeficiency following genetic ablation of Mcl1 in natural killer cells

The cytokine IL-15 is required for natural killer (NK) cell homeostasis; however, the intrinsic mechanism governing this requirement remains unexplored. Here we identify the absolute requirement for myeloid cell leukaemia sequence-1 (Mcl1) in the sustained survival of NK cells in vivo. Mcl1 is highly expressed in NK cells and regulated by IL-15 in a dose-dependent manner via STAT5 phosphorylation and subsequent binding to the 3'-UTR of Mcl1. Specific deletion of Mcl1 in NK cells results in the absolute loss of NK cells from all tissues owing to a failure to antagonize pro-apoptotic proteins in the outer mitochondrial membrane. This NK lymphopenia results in mice succumbing to multiorgan melanoma metastases, being permissive to allogeneic transplantation and being resistant to toxic shock following polymicrobial sepsis challenge. These results clearly demonstrate a non-redundant pathway linking IL-15 to Mcl1 in the maintenance of NK cells and innate immune responses in vivo