bluuebunny/crossref_metadata_2025 huggingface dataset:
Preoperative facet joint arthropathy does not impact long-term clinical outcomes after lumbar-stability-preserving decompression and dynesys fixation
Authors: Chou Po-Hsin , Lin Hsi-Hsien , Yao Yu-Cheng , Wang Shih-Tien , Chang Ming-Chau , Liu Chien-Lin
Published: May 2021

To evaluate the impact of the preoperative severity of facet joint arthropathy on long-term functional outcomes and spinopelvic parameters in patients undergoing lumbar-stability-preserving decompression and Dynesys fixation. In this retrospective study, 88 patients undergoing combined surgery at our hospital from 2008 to 2015 were included. The patients were divided into two groups, the less and more than mean degeneration groups, based on preoperative facet joint arthropathy of the index level(s). The clinical outcomes were the Visual Analogue Scale (VAS) score, the Oswestry Disability Index (ODI) score and spinopelvic parameters. The mean follow-up durations for the less and more than mean degeneration groups were 84.83 ± 27.58 and 92.83 ± 20.45 months, respectively. The combined surgery significantly improved VAS and ODI scores, and increased sacral slope (SS) regardless of preoperative arthropathy severity. In addition, facet joint arthropathy at adjacent levels continued to worsen after surgery in both arthropathy severity groups. Preoperative facet joint arthropathy did not influence most long-term clinical outcomes in patients undergoing lumbar-stability-preserving decompression and Dynesys fixation. This combined surgery may be suitable for patients with facet joint arthropathy regardless of disease severity.
Controlled deposition of nanoparticles with critical Casimir forces
Authors: Marino Emanuele , Vasilyev Oleg A. , Kluft Bas B. , Stroink Milo J. B. , Kondrat Svyatoslav , Schall Peter
Published: May 2021

Nanocrystal assembly represents the key step to develop next-generation optoelectronic devices with properties defined from the bottom-up. In this paper, we show that the critical Casimir effect allows direct control over superstructure morphology.
Trapped interfacial redox introduces reversibility in the oxygen reduction reaction in a non-aqueous Ca2+ electrolyte
Authors: Lu Yi-Ting , Neale Alex R. , Hu Chi-Chang , Hardwick Laurence J.
Published: May 2021

An interlayer product of oxygen reduction with Ca2+/TBA+ yields a quasi-reversible oxygen evolution reaction by inducing a trapped interfacial redox process.
Enzyme-responsive fluorescent nanoemulsion based on lipophilic dye liquid
Authors: Oishi Ryoutarou , Maki Kaho , Mizuta Tatsumi , Sueyoshi Kenji , Endo Tatsuro , Hisamoto Hideaki
Published: May 2021

An enzyme-responsive fluorescent nanoemulsion (NE) based on lipophilic dye liquid (LDL) was developed for alkaline phosphatase (ALP).
Thermal equilibria between conformers enable highly reliable single-fluorophore ratiometric thermometers
Authors: Shen Tianruo , Wu Xia , Tan Davin , Xu Zhaochao , Liu Xiaogang
Published: May 2021

We proposed a simple method to establish the single-fluorophore ratiometric thermometers based on the conversion between conformers of fluorophores in the ground state. This design method is applicable to many widely available fluorophores.
Investigation of the mechanical effects of targeted drugs on cancerous cells based on atomic force microscopy
Authors: Zhu Jiajing , Tian Yanling , Wang Zuobin , Wang Ying , Zhang Wenxiao , Qu Kaige , Weng Zhankun , Liu Xianping
Published: May 2021

Morphology and adhesion characterization for SMMC-7721 cells based on the AFM.
Encapsulating an acid-activatable phthalocyanine–doxorubicin conjugate and the hypoxia-sensitive tirapazamine in polymeric micelles for multimodal cancer therapy
Authors: Guo Xuejiao , Jin Honglin , Lo Pui-Chi
Published: May 2021

A multicomponent nanodrug based on polymeric micelles has been fabricated and examined for its potential in combined photodynamic therapy, chemotherapy and hypoxia-activated therapy of cancer.
Glass transition and dynamics of semiflexible polymer brushes
Authors: Huang Jian-Hua , Sun Dan-Dan , Lu Rong-Xing
Published: May 2021

The glass transition of semiflexible polymer brushes is in synchronism with an abrupt change in chain conformation and segment dynamics.
Sequence-selective recognition of cationic amphipathic tripeptides with similar structures in aqueous solutions by cucurbit[7]uril
Authors: Ma Fenfen , Zheng Xiaoyan , Li Zesheng
Published: May 2021

CB[7] can differentiate WGR and WGK with similar structures efficiently because of their eight orders of magnitude difference in Ka.
Correction: Antiviral drug design based on the opening mechanism of spike glycoprotein in SARS-CoV-2
Authors: Mao Ruichao , Bie Lihua , Xu Maofeng , Wang Xiaocong , Gao Jun
Published: May 2021

Correction for ‘Antiviral drug design based on the opening mechanism of spike glycoprotein in SARS-CoV-2’ by Ruichao Mao et al., Phys. Chem. Chem. Phys., 2021, DOI: 10.1039/d1cp01045j.
Photochemical radical cyclization reactions with imines, hydrazones, oximes and related compounds
Authors: Latrache Mohammed , Hoffmann Norbert
Published: May 2021

Photochemical reactions of imines, hydrazones, oximes and related compounds provides an efficient access to radical intermediates in the synthesis of heterocycles.
A mechanistic investigation of the Suzuki polycondensation reaction using MS/MS methods
Authors: Ting Michelle Y. C. , Yunker Lars P. E. , Chagunda Ian C. , Hatlelid Katherine , Vieweg Meghan , McIndoe J. Scott
Published: May 2021

The Suzuki polycondensation can be studied in real time using MS/MS methods, even with the molecular weight of the reaction components changing with every turnover.
Coordination networks for the recognition of oxo-anions
Authors: Kaur Harpreet , Sinha Sougata , Krishnan Venkata , Koner Rik Rani
Published: May 2021

Utilization of luminescent crystalline coordination networks (LCPs/LMOFs) for the recognition of various oxo-anions in aqueous environment has received significant interest in the context of environmental remediation.
Mechanochromic luminescence properties of fluoro-substituted pinene-containing cyclometalated platinum(ii) complexes with multiple triplet excited states
Authors: Yang Qian-Ying , Zhang Hua-Hong , Qi Xiao-Wei , Sun Shi-Shu , Zhang Da-Shuai , Han Li-Zhi , Zhang Xiao-Peng , Shi Zai-Feng
Published: May 2021

The distinct and reversible mechanochormic luminescence of as-prepared yellow solids of (−)-2 are displayed. The interplay of 3π,π* monomer and excimer/3MMLCT excited states is supposed to be the key for mechanochromic luminescence.
The comparative studies on the magnetic relaxation behaviour of the axially-elongated pentagonal-bipyramidal dysprosium and erbium ions in similar one-dimensional chain structures
Authors: Wang Fei , Gong Hui-Wen , Zhang Yan , Xue An-Qi , Zhu Wen-Hua , Zhang Yi-Quan , Huang Zhen-Na , Sun Hao-Ling , Liu Bei , Fang Yue-Yi , Gao Song
Published: May 2021

Comparative studies on magnetic properties were conducted for the axially-elongated pentagonal-bipyramidal dysprosium and erbium ions in a family of cyano-bridged 3d–4f one-dimensional chain compounds.
Rapid and mild synthesis of Au–NHC complexes in a simple two-phase flow reactor
Authors: Jónsson Helgi Freyr , Fiksdahl Anne , Harvie Andrew J.
Published: May 2021

We demonstrate a flow reactor capable of synthesising Au–NHC complexes rapidly and with minimal workup.
Effect of dandelion root polysaccharide on the pasting, gelatinization, rheology, structural properties and in vitro digestibility of corn starch
Authors: Gao Jingyu , Zhu Ling , Huang Jing , Li Lianyu , Yang Yu , Xu Yaqin , Wang Yabin , Wang Libo
Published: May 2021

The influence of dandelion root polysaccharide (DRP) on the gelatinization properties and in vitro digestibility of corn starch was investigated.
A mathematical analysis of carbon fixing materials that grow, reinforce, and self-heal from atmospheric carbon dioxide
Authors: Parviz Dorsa , Lundberg Daniel J. , Kwak Seonyeong , Kim Hyunah , Strano Michael S.
Published: May 2021

Carbon fixing materials use ambient CO2 to add to an extending carbon backbone. Here, reaction engineering and materials analysis answer questions about the maximum growth rate, photocatalytic requirements, and limits of applicable materials.
Catalyst- and solvent-free Csp2–H functionalization of 4-hydroxycoumarins via C-3 dehydrogenative aza-coupling under ball-milling
Authors: Brahmachari Goutam , Karmakar Indrajit , Karmakar Pintu
Published: May 2021

A mechanochemistry-driven green and efficient synthetic protocol for bio-relevant coumarin-hydrazones from a one-pot three-component reaction between 4-hydrocoumarins, primary aromatic amines and tert-butyl nitrite under ball-milling has been developed.
Nucleation and growth of blue phase liquid crystals on chemically-patterned surfaces: a surface anchoring assisted blue phase correlation length
Authors: Li Xiao , Park Kangho , Guzmán Orlando , Martínez-González José A. , Dolan James A. , de Pablo Juan J. , Nealey Paul F.
Published: May 2021

The correlation length of blue phases—defined as the distance over which the same BP-lattice orientation is maintained—is revealed along different kinetic pathways and time evolution by liquid epitaxial growth.
Recent advances in graphite carbon nitride-based nanocomposites: structure, antibacterial properties and synergies
Authors: Yan Kai , Mu Chenglong , Meng Lingjie , Fei Zhaofu , Dyson Paul J.
Published: May 2021

In this review, the research progress for enhanced photocatalytic antibacterial performance of g-C3N4 based nanocomposites is discussed through different topologies, noble metal decoration, non-noble metal doping and heterojunction construction.
Contribution of nitrogen configurations to the adsorption of Cd(ii) in nitrogen-enriched biochar
Authors: Jiang Yu , Yang Chen , Yao Qian , Deng Yurong , Yang Jingjing , Liu Yanjun , Ouyang Zhuozhi , Huang Weilin , Dang Zhi
Published: May 2021

Graphitic-N in a carbon framework can form cationic–π interactions with Cd(ii) to promote adsorption.
Controlled individual and partial polyethylene nanofibers with high Tm2 prepared by PPM-supported Cp2TiCl2 catalysts
Authors: Wang Kui , Shen Lu , Zhou Guangyuan
Published: May 2021

Controlled individual and partial nanofibrous polyethylenes with high second melting point (Tm2) were obtained through ethylene-confined polymerization using a porous polymer microsphere (PPM)-supported Cp2TiCl2 catalyst.
Flaky cobalt phosphide-modified manganese iron oxide as a highly efficient OER catalyst
Authors: Li Shumei , Lei Xiang , Hu Huixia , Fu Liwen , Peng Ruzhen , Huang Haiping , Wang Jinliang
Published: May 2021

Novel CoP modified manganese ferrite was synthesized by a new strategy, showing efficient OER catalytic performance.
Psidguajones A and B, a pair of complex meroterpenoid epimers from the leaves of Psidium guajava
Authors: Liu Qing , Wang Zhichao , He Jianming , Liu Zhenling
Published: May 2021

Psidguajones A and B, a pair of dimeric sesquiterpene-based meroterpenoid epimers, have been isolated from the leaves of Psidium guajava for the first time.
Unusual C3-acetylation of quinoxalin-2(1H)-one via oxidative C–C and C–O bond cleavages of PEG-400
Authors: Kudale Vishal Suresh , Mutra Mohana Reddy , Chu Ching-Piao , Wang Jeh-Jeng
Published: May 2021

Aerobic oxidative tandem conversion of PEG-400 to acetyl radical via C–C and C–O bond cleavages followed by silver-catalyzed menisci-type addition to the C3 position of quinoxalin-2(1H)-one is described.
Higher-order interfiber interactions in the self-assembly of benzene-1,3,5-tricarboxamide-based peptides in water
Authors: Zagorodko Oleksandr , Melnyk Tetiana , Rogier Olivier , Nebot Vicent J. , Vicent María J.
Published: May 2021

Benzene-1,3,5-tricarboxamide-based di- and tripeptide derivatives can form various higher-order structures in aqueous solution depending on the order, hydrophobicity, and bulkiness of the amino acids in the substituent.
Sodium ion intercalation and multi redox behavior of a Keggin type polyoxometalate during [PMo10V2O40]5−to [PMo10V2O40]27−as a cathode material for Na-ion rechargeable batteries
Authors: Priyadarshini Marimuthu , Shanmugan Swaminathan , Kirubakaran Kiran Preethi , Thomas Anoopa , Prakash Muthuramalingam , Vediappan Kumaran
Published: May 2021

The versatile property of the Keggin type POM is the multi-electron transfer that happens during the switching between [PMo10V2O40]5−to [PMo10V2O40]27−. This tunable behavior makes it unique, efficient material as a cathode for Na-ion batteries.
Recovery of rare earth elements by nanometric CeO2 embedded into electrospun PVA nanofibres
Authors: Comandella Daniele , Bonani Walter , Ciscar Jorge Bañuls , Ponti Jessica , Cologna Marco , Popa Karin , Gilliland Douglas
Published: May 2021

Electrospun poly(vinyl alcohol) membranes with nano CeO2 could effectively recover rare earth ions from model water solutions.
A simple method for the preparation of a nickel selenide and cobalt selenide mixed catalyst to enhance bifunctional oxygen activity for Zn–air batteries
Authors: Peng Li-Juan , Huang Jie-Ping , Pan Qiu-Ren , Liang Ying , Yin Na , Xu Hang-Chang , Li Nan
Published: May 2021

The mixture Ni0.85Se/Co0.85Se-NHCS-2 displayed superior electrocatalytic performance to that of Ni0.85Se-NHCS or Co0.85Se-NHCS alone. This provided a simple approach to develop ORR/OER bifunctional electrocatalysts for zinc–air batteries.
Incorporating concept development activities into a flipped classroom structure: using PhET simulations to put a twist on the flip
Authors: Wu Hoi-Ting , Mortezaei Kiana , Alvelais Teresa , Henbest Grace , Murphy Courtney , Yezierski Ellen J. , Eichler Jack F.
Published: May 2021

Implementation of the flipped classroom approach into STEM courses has been popularized in the last decade and has generally been reported to improve student performance outcomes. In a flipped classroom setting, students typically first encounter course content in the online format and subsequently engage in some form of active learning during the in-person class meetings. Although the flipped classroom approach can promote increased student engagement and provide an opportunity to apply content encountered in the classroom, this structure does not generally give students opportunities for discrete concept development prior to the application phase of learning. In an effort to build concept development activities into a flipped classroom structure, five learning cycle activities were implemented in a large enrollment first-term general chemistry course that has previously implemented the flipped classroom design. Four of these learning cycle activities incorporated PhET simulations as part of the exploration phase of learning, and all five activities were facilitated during the in-person class meetings to initiate the learning cycle. The activities were designed to help students explore models and engage in concept development. The application phase of the learning cycle was facilitated by flipped classroom modules or in-person classroom activities that included whole-class questioning coupled with collaborative think-pair-share discussion. Performance gains in conceptual understanding were evaluated by employing a one-group, pre-post-post research design. Non-parametric Friedman's tests indicate a significant main effect across time for each concept development activity, and post hoc Wilcoxon signed rank tests indicate the post-test and final exam scores are significantly higher than the pre-test scores for each activity (p < 0.001 for each pre-post and pre-final pairwise comparison). The findings reported herein demonstrate that concept development activities can be successfully integrated with flipped classroom modules and the combination of the introductory learning cycle activities and flipped classroom application activities led to knowledge gains that persisted through the end of the course. In total, creating this type of blended learning environment appears to help students achieve understanding of core general chemistry concepts.
A dual-caged resorufin probe for rapid screening of infections resistant to lactam antibiotics
Authors: Xie Jinghang , Mu Ran , Fang Mingxi , Cheng Yunfeng , Senchyna Fiona , Moreno Angel , Banaei Niaz , Rao Jianghong
Published: May 2021

This work reports a dual-caged fluorogenic probe and its demonstration for rapid and sensitive screening of as low as 1000 clinically isolated β-lactamase-expressing bacteria per milliliter urine samples within 2 hours.
Olivine LiMnxFe1−xPO4 cathode materials for lithium ion batteries: restricted factors of rate performances
Authors: Yang Li , Deng Wentao , Xu Wei , Tian Ye , Wang Anni , Wang Baowei , Zou Guoqiang , Hou Hongshuai , Deng Weina , Ji Xiaobo
Published: May 2021

The research progress on the factors restricting of LMFP rate performance has been comprehensively elaborated with respect to three aspects: intrinsic properties, interface structure and cell preparation.
Ultrafast fabrication of organohydrogels with UV-blocking, anti-freezing, anti-drying, and skin epidermal sensing properties using lignin–Cu2+ plant catechol chemistry
Authors: Sun Dan , Li Nan , Rao Jun , Jia Siyu , Su Zhenhua , Hao Xiang , Peng Feng
Published: May 2021

Motivated by plant catechol chemistry, we demonstrated a self-catalytic lignin/Cu2+ system to rapidly fabricate multifunctional organohydrogels at room temperature without the removal of oxygen.
A new strategy of nanocompositing vanadium dioxide with excellent durability
Authors: Zhou Xin , Meng Yun , Vu Tuan Duc , Gu Deen , Jiang Yadong , Mu Qian , Li Yatao , Yao Bingqing , Dong Zhili , Liu Qing , Long Yi
Published: May 2021

We developed a new strategy to fabricate a VO2 coating with long-term stability, a low τc (42.4 °C heating, 36.5 °C cooling), significantly enhanced thermochromic performance (Tlum of 35.7% and ΔTsol of 13.2%) and low fabrication cost.
Investigating Acoustic Correlates of Intelligibility Gains and Losses During Slowed Speech: A Hybridization Approach
Authors: van Brenk Frits , Kain Alexander , Tjaden Kris
Published: May 2021

Purpose

This exploratory study sought to identify acoustic variables explaining rate-related variation in intelligibility for speakers with dysarthria secondary to multiple sclerosis.

Method

Seven speakers with dysarthria due to multiple sclerosis produced the same set of Harvard sentences at habitual and slow rates. Speakers were selected from a larger corpus on the basis of rate-related intelligibility characteristics. Four speakers demonstrated improved intelligibility and three speakers demonstrated reduced intelligibility when rate was slowed. A speech analysis resynthesis paradigm termedhybridizationwas used to create stimuli in which segmental (i.e., short-term spectral) and suprasegmental variables (i.e., sentence-level fundamental frequency, energy characteristics, and duration) of sentences produced at the slow rate were donated individually or in combination to habitually produced sentences. Online crowdsourced orthographic transcription was used to quantify intelligibility for six hybridized sentence types and the original habitual and slow productions.

Results

Sentence duration alone was not a contributing factor to improved intelligibility associated with slowed rate. Speakers whose intelligibility improved with slowed rate showed higher intelligibility scores for duration spectrum hybrids and energy hybrids compared to the original habitual rate sentences, suggesting these acoustic cues contributed to improved intelligibility for sentences produced with a slowed rate. Energy contour characteristics were also found to play a role in intelligibility losses for speakers with decreased intelligibility at slowed rate. The relative contribution of speech acoustic variables to intelligibility gains and losses varied considerably between speakers.

Conclusions

Hybridization can be used to identify acoustic correlates of intelligibility variation associated with slowed rate. This approach has further elucidated speaker-specific and individualized speech production adjustments when slowing rate.
Simulation of positive streamer propagation in an air gap with a GFRP composite barrier
Authors: He Hengxin , Xia Dezhi , Luo Bin , Chen Weijiang , Bian Kai , Xiang NianWen
Published: May 2021

The puncture of glass fibre reinforced polymer (GFRP) laminate is a primary damage pattern of wind turbine blades due to lightning strikes. A numerical simulation model of positive streamer propagation in a needle‐to‐plate air gap with a GFRP laminate is established to investigate the breakdown mechanism of GFRP laminate. The model not only considers the dynamics of charged particles in the air and the composite laminate, but also the current continuity at gas–solid interfaces. The simulated streamer discharge pattern and the surface streamer length are in good agreement with the observation results. The distributions and evolutions of the electron number density, electric field, and surface charge densities during streamer propagation are obtained. It is found that the enhancement of the electric field on the GFRP laminate is caused by the rapid deposition of positive and negative space charges on the GFRP laminate after a secondary streamer incepts on the lower surface of the GFRP laminate. The effects of the applied voltage, relative permittivity, and thickness of the GFRP laminate on the electric field on the GFRP laminate are investigated. The obtained results could assist in further understanding of the mechanism of GFRP wind blade breakdown due to lightning strikes.
Cosmic radio dipole: Estimators and frequency dependence
Authors: Siewert Thilo M. , Schmidt-Rubart Matthias , Schwarz Dominik J.
Published: May 2021

The cosmic radio dipole is of fundamental interest to studies of cosmology. Recent works have put forth open questions about the nature of the observed cosmic radio dipole. In the current work, we use simulated source count maps to test a linear and a quadratic estimator for possible biases in the estimated dipole amplitude with respect to the masking procedure. We find a superiority on the part of the quadratic estimator, which we used to analyse the TGSS-ADR1, WENSS, SUMSS, and NVSS radio source catalogues, spread over a decade of frequencies. We applied the same masking strategy to all four surveys to produce comparable results. In order to address the differences in the observed dipole amplitudes, we cross-matched the two surveys located at both ends of the analysed frequency range. For the linear estimator, we identified a general bias in the estimated dipole directions. The positional offsets of the quadratic estimator to the cosmic microwave background (CMB) dipole for skies with 107 simulated sources is found to be below one degree and the absolute accuracy of the estimated dipole amplitudes is better than 10−3. For the four radio source catalogues, we find an increasing dipole amplitude with decreasing frequency, which is consistent with results from the literature and the results of the cross-matched catalogue. We conclude that for all analysed surveys, the observed cosmic radio dipole amplitudes exceed the expectations derived from the CMB dipole, which cannot strictly be explained by a kinematic dipole alone.
An update of the correlation between polarimetric and thermal properties of cometary dust
Authors: Kwon Yuna G. , Kolokolova Ludmilla , Agarwal Jessica , Markkanen Johannes
Published: May 2021

Context.Comets are conglomerates of ice and dust particles, the latter of which encode information on changes in the radiative and thermal environments. Dust displays distinctive scattered and thermal radiation in the visible and mid-infrared (MIR) wavelengths, respectively, based on its inherent characteristics.

Aims.We aim to identify a possible correlation between the properties of scattered and thermal radiation from dust and the principal dust characteristics responsible for this relationship, and therefrom gain insights into comet evolution.

Methods.We use the NASA/PDS archival polarimetric data on cometary dust in the red (0.62−0.73 μm) and K (2.00−2.39 μm) domains to leverage the relative excess of the polarisation degree of a comet to the average trend at the given phase angle (Pexcess) as a metric of the dust’s scattered light characteristics. The flux excess of silicate emissions to the continuum around 10 μm (FSi/Fcont) is adopted from previous studies as a metric of the dust’s MIR feature.

Results.The two observables –PexcessandFSi/Fcont– show a positive correlation whenPexcessis measured in the K domain (Spearman’s rank correlation coefficientρ= 0.71−0.19+0.10). No significant correlation was identified in the red domain (ρ= 0.13−0.15+0.16). The gas-rich comets have systematically weakerFSi/Fcontthan the dust-rich ones, and yet both groups retain the same overall tendency with different slope values.

Conclusions.The observed positive correlation between the two metrics indicates that composition is a peripheral factor in characterising the dust’s polarimetric and silicate emission properties. The systematic difference inFSi/Fcontfor gas-rich versus dust-rich comets would instead correspond to the difference in their dust size distribution. Hence, our results suggest that the current MIR spectral models of cometary dust, which search for a minimumχ2fit by considering various dust properties simultaneously, should prioritise the dust size and porosity over the composition. With light scattering being sensitive to different size scales in two wavebands, we expect the K-domain polarimetry to be sensitive to the properties of dust aggregates, such as size and porosity, which might have been influenced by evolutionary processes. On the other hand, the red-domain polarimetry reflects the characteristics of sub-micrometre constituents in the aggregate.
Modification of polyvinylchloride by the silicates on the base of rice husk
Authors: Gotlib Elena , Sadykova Dilyara , Yamaleeva Ekaterina , Sokolova Alla
Published: May 2021

As a modifying additive in PVC-compositions, silicates produced by means of rice husk processing are of practical interest. Rice husk ash obtained by burning at 350°C, along with synthetic and naturally occurring wollastonite, significantly reduce plasticizer’s migration from the PVC-composition due to their porosity. This is due to the fact that the part of hydroxyl components of the plasticizer EDOS has adsorbed on the surface or retained by the silicates pores. Along with that, Miwoll 10-97 ensures a greater decrease in plasticizer’s migration than synthetic calcium silicate on the base of rice husk ash. When all the researched silicates are modified by the rice husk and naturally occurring wollastonite, heat stability of PVC-compositions grows. This is preconditioned by the alkaline origin of the surface of filling compounds that allows their possible reaction with chlorine hydride released from PVC during thermal decomposition. Synthetic and naturally occurring wollastonite enhance strain-strength properties of PVC-compositions whereas silicates on the case of rice husk reduce these parameters.
Modified high-strength concrete with the addition of CONPLAST SP430
Authors: Kalbaev Baxauatdin , Utegenova Gulzar , Ilyasov A. , Gandjuntsev Mikhail
Published: May 2021

In most high-strength concrete technologies, high-quality Portland cements are used, which is not always achievable in conditions of a shortage of such binders.

The research’s purpose is to obtain high-strength concrete based on ordinary Portland cement of the M400 brand. To achieve this goal, the possibility of using the superplasticizer Conplast SP430 was studied.

The research was carried out using standard methods, like using mathematical planning and result’s analytical processing.

The implementation of the experiment allowed us to determine the optimal values of the basic composition of concrete: the consumption of superplasticizer-1.0 % of the mass of cement; the consumption of cement-485 kg/m3, the ratio of sand/crushed stone-0.36. At the optimal value of the parameters, the achieved maximum compressive strength was 58.8 MPa.

The novelty is the justification of the possibility of obtaining high-strength concretes using Portland cement with an activity not exceeding 40 MPa based on the use of a new generation superplasticizer and the development of the basics of the method for selecting the composition of concrete.

The significance of the result is due to the expansion of the possibility of using ordinary Portland cement for the production of products and structures with the use of high-strength concrete.
Building a nomogram to predict maximum temperature in mass concrete at an early age
Authors: Nguyen Trong - Chuc , Nguyen Van - Quang , Aniskin Nikolay , Phung Ba - Thang , Hoang Quoc - Long
Published: May 2021

During the construction of massive concrete structures, the main factor that affects the structure is temperature. The resulting temperature is the result of hydration of the cement and some other factors, which leads to the formation of thermal cracks at an early age. So, the prediction of temperature history in massive concrete structures has been a very important problem. In this study, with the help of numerical methods, a temperature nomogram was built to quickly determine the maximum temperature in concrete structures with different parameters such as size, cement content, and the initial temperature of the concrete mixture. The obtained temperature nomogram has been compared with the results of the finite element method and the model experiment gives reliable results. It can be used to predict maximum temperature in mass concrete structures to prevent the formation of thermal cracks.
Shredding of polyethylene terephthalate waste
Authors: Fomina Natalya , Khozin Vadim , Strakhov Aleksandr , Ismagilov Artur
Published: May 2021

Methods of recycling polyethylene terephthalate waste are analyzed. Thermoplastic waste has great potential for mechanical recycling. Lack of information on the quality of recycled products and their applicability for specific purposes hinders their use. Shredding is a main process in mechanical recycling. Due to the viscoelastic properties, the cost of grinding polymer waste is several times higher than for most brittle mineral materials. Cutting and impact equipment is often used to shred plastic waste. To obtain micron-sized polymer particles, the technologies of cryogenic grinding and wet grinding in solvents are used, which is followed by high operating costs. The purpose of this work was to develop an economical method for producing fine powders from polyethylene terephthalate waste. The specific surface of the powders has been investigated. To investigate the destruction, differential thermal analysis and infrared spectroscopy were used. The technology of secondary mechanical recycling is proposed: crushing, melting of waste, natural or water cooling of the melt, grinding on equipment typical for brittle materials. A dispersed product with a proportion of micronized fraction of about 50% was obtained for use as filler in composites. The resulting product is more degraded in comparison with the feedstock. Therefore, its use as binders is advisable in applications where a decrease in initial properties is permissible, in products with a long lifecycle, for example, in the production of building materials. The use of waste thermoplastic in applications other than the original one does not always reduce the value of the technology.
Prospects for the use of sandwich panels in the construction industry of Kazakhstan
Authors: Omarov Zhumabek , Zhukenova Gulnara , Bulyga Leonid , Beisembaev Murat
Published: May 2021

One of the main priorities for the implementation of the tasks set in the Address of the Head of State Nursultan Nazarbayev to the people of Kazakhstan “Kazakhstan’s way - 2050: common goal, common interests, common future” is the transition of traditional industries of Kazakhstan to the production of high value added products.

Structural insulated panel (SIP) in common people is a sandwich panel. Aside from the architectural and aesthetic requirements for building projects, sandwich panels could be called the ideal building material.

The shell of sandwich panels is made with a good and reliable anti-corrosion coating, the insulation material has a low thermal conductivity, minimal moisture absorption, sufficient mechanical strength, and high durability. And the sandwich panel itself is resistant to harmful ultraviolet radiation, atmospheric and mechanical influences. In addition, any communications are easily laid through sandwich panels: drilling or cutting this structure is much easier than reinforced concrete panels.
Calculations of compressed rods considering experiments over last 100 years
Authors: Konin Denis
Published: May 2021

The article presents the results of testing and FE-modelling of rods calculated for the central and eccentric compressive load. More than 600 tests have been analysed over the past 100 years, including made by author, in a wide range of slenderness made of steels with a yield strength of up to 1000 MPa. It is established that the existing Russian calculation methods allow us to accurately determine the bearing capacity of the rod for steel of any strength. Verification of calculation method was carried out not only by stresses and ultimate load-bearing capacity, but also by the deformations of the tested rods. It is established that for H-beams and thin- walled pipes, clarification of the design codes is required to be able to design cost-effective designs, since the code formulas give a margin. This is especially true for elements of low flexibility with small eccentricities. To clarify the codes, a method for modelling a three-line diagram of steel operation, verified with the test results, is proposed.
Solution of Thermal Conductivity Problem of a Finite Dimensions Plate with Two Heat Sources
Authors: Gulkanov Aleksandr , Modestov Konstantin , Usikov Sergey
Published: May 2021

Research in the basic sciences is a critical factor in the development of the civil engineering industry. Solving the problems of radiation-convective heat transfer from heated surfaces has always aroused interest from the point of view of science and practical engineering application of knowledge. However, analytical solutions to these problems are obtained for elementary cases, for example, for infinite plates heated uniformly, or the propagation of heat waves in them obeys certain laws. The solution of the coupled problem of radiation-convective transfer from the surface of these panels is complicated not only by the geometric shape, but also by the openness of the entire thermophysical system, which includes the transfer of thermal energy from the coolant (coolant for cooling systems) to the surface of the thermal panel, from the panel to the room air by convection, and radiation to surrounding bodies (enclosing structures, furniture, people). In turn, additional heat exchange by convection occurs between the air and the enclosing structures. This article considers the possibility of obtaining an analytical solution to the problem of temperature distribution on the surface of a plate with two heat sources. When deriving the formulas, the classical equations of thermodynamics (Newton-Richmann, Fourier’s law, Helmholtz equation) were used. The general solution of the differential equation, in this case, is a linear combination of the Infeld and MacDonald functions. The research results can be applied to various areas of technical sciences: cooling of microprocessors, renewable sources of thermal energy, thermal and cooling panels for industrial production, automotive, marine shipbuilding, and of course heating and air conditioning systems for buildings and transport.
Research of a third-order nonlinear differential equation in the vicinity of a moving singular point for a complex plane
Authors: Orlov Victor , Gasanov Magomedyusuf
Published: May 2021

This article generalizes the previously obtained results of existence and uniqueness theorems for the solution of a third-order nonlinear differential equation in the vicinity of moving singular points in the complex domain, as well as constructs an analytical approximate solution, and obtains a priori estimates of the error of this approximate solution. The study was carried out using the modified method of majorants to solve this equation, which differs from the classical theory, in which this method is applied to the right-hand side of the equation The final point of the article is to conduct a numerical experiment to test the theoretical positions obtained.
Formation of harmful volatile substances in sewage systems and their neutralization
Authors: Orlov Vladimir , Zotkin Sergey
Published: May 2021

The study of the ways of harmful volatile substance formation in sewerage systems, as well as a rapid and economical neutralization of these substances by construction, mechanical, physical and chemical, hydrodynamic and other methods is an urgent task that contributes to the protection of humans and the environment from toxic pollutants. The purpose of the presented studies is evaluation of the effectiveness of the impact on harmful volatile substances, through application of various methods designed to completely eliminate the conditions for the occurrence of odors harmful to human health or significantly reduce their amount to the maximum permissible concentrations in the airspace of cities. The methods have considered the description of the available ways of the odor identification by chemical and organoleptic analysis. The results provide a description of methods for blocking the formation of volatile substances. The operational works (methods of pipeline cleaning, ventilation, dosing of chemicals in waste waters) have been considered as the blocking measures, and the construction design ones (reconstruction of networks and facilities, biological, thermal, catalytic, electro-physical and other gas treatment methods) have been considered as the ways to reduce the spread of noxious odors. As a conclusion, it is noted that the complete elimination of the harmful volatile substance problem is possible by taking comprehensive measures to eliminate (minimize) the emission of gases into the environment.
Coagulation of waste water from the point of view of physic-chemical interactions
Authors: Alekseev Evgeny , Shambina Svetlana
Published: May 2021

The widespread use of reagent coagulation in the technology of purification of natural and waste waters is due to the complexity of the chemical composition and phase-dispersed state of the aqua systems of these waters, on the one hand, and the multifactorial action of coagulants on them, on the other. The mechanisms of interaction between coagulants and pollutants of wastewater which are in different phase-dispersed states include the physicochemical phenomena of coagulation, heterocoagulation, adagulation and sorption. The physicochemical concept “coagulation” reflects only one mechanism of coagulants’ action on pollutants. This leads to the appearing of the problem in terminological description of the physicochemical processes’ combined action when adding coagulants to the water being cleaned. The purpose of the study is to justify the use of universal indicators characterizing the multifactorial nature of the coagulation process, its formalization and quantitative assessment. The solution of the problem is to use the concept of “coasorption”, which determines the multifactorial nature of the interaction between coagulants and pollutants, and to use the technological indicator “specific coasorption”, which establishes a quantitative relationship between the pollutants’ indicators and the dose of coagulant. The test coagulation’s results of two different types of synthetic dyes’ solutions using aluminum salts reflect the difference in the mechanisms of their interaction with the coagulant. The formula for coasorption isotherm can be used to determine the required doses of reagents for coagulation of water basing on the initial and residual content of pollutants in the purified waters.
Specifying DHW heat demand profiles according to operational data: enhancing quality of a DH system model
Authors: Chicherin Stanislav , Zhuikov Andrey , Kolosov Mikhail , Junussova Lyazzat , Aliyarova Madina , Yelemanova Aliya
Published: May 2021

For a DH network a meticulous analysis is required to detect a correlation of a reduction in energy demand from one year to another. The factors, which lead to such inconsistency, force an energy company (1) to modernize equipment at a consumer side and (2) to lower network operating temperatures. It results into so called fourth generation district heating (4GDH). The current research focuses on large-scale DH systems and DHW as second largest share of heat demand. The heat delays, thermal inertia and DHW consumption patterns are specified further since they might represent a natural heating accumulator. In this case, daily flow changes are considered, as they influence a DH system performance and desirable TES capacity. However, more precise profiles can be achieved by detecting the actual flow curve, and measuring the temperature difference between substation supply and return line. The dimensioning of DH systems requires comprehensive understanding of simultaneity factors. Thus, we consider substations with DHW preparation to choose the optimal size of the heat distribution network according to the new method. Case study is a DH system in Omsk, which includes residential houses (both SH and DHW coverage), and university buildings (more demand results from process heat). The operation of the system was studied for the period from the 1st of January to 31st of December 2020. We suggest a TES with a capacity of 0.04 MWh; based on the traditional temperature range, the volume is about 0.5 m3. Daily compensation time is 2-3 hours, when there is a reduction in the supply flow rate of 1500 t/h with minimum DH plant make-up. The entire DH system requires about 400 t of hot water make-up to reach the quasi-steady state conditions after the night DHW shutdown. Using the threshold of the traditional model, it hardly fits an operational value - it is better set according to novel method (0.1 MW). For similar relations between circulation and DHW flow rates, the systems with a HE result in higher circulating flows than the substations with no one. The consumer benefit from consuming DHW and heat according to more accurate profiles accounts 1.72 billion USD. It is quantified by considering avoiding using a back-up electricity source to ensure DHW service when a DH plant supplies enough heat. Moreover, if a TES is controlled according to the method detailed, it alleviates the stress for intermittent operation by compensating the transients of SH and DHW loads. 4GDH concept should be considered according to: (1) the operational data, (2) new DHW demand assessments, and (3) using TES to buffer peaks.
Evaluation of the effectiveness of additional thermal insulation of the basement floor of frame-monolithic buildings in extreme operating conditions
Authors: Kornilov Terentii , Fedotov Petr , Nikiforov Aleksandr
Published: May 2021

The issues of saving energy resources are of particular relevance for the regions of Russia with an extremely cold climate. The increased air pressure difference in winter and the presence of volumetric cold bridges in the form of pile and column grillages, basement slabs and concrete block masonry often leads to a violation of the temperature regime of the first floors of multi-storey buildings with a monolithic reinforced concrete frame. Thermal analysis of fragments of basement floors in areas with columns and grillages with additional thermal insulation from the outside was carried out. The low efficiency of the external thermal insulation of the basement elements of the operated frame-monolithic buildings is shown.
Spring diagrams for the visualization of construction project dynamics
Authors: Undozerov Vadim
Published: May 2021

Construction projects are very dynamic, so change management is crucial there. Changes in schedule and in stakeholders relationships are among the most important change management areas. Making decisions on such changes is an extremely difficult task. It can be facilitated by special visualization techniques. The existing techniques are analyzed and their drawbacks revealed. In order to address these drawbacks, new techniques are proposed for the visualization of both schedule and stakeholders relationships changes. They are based on the application of the spring image used in mechanics to the visualization of the project’s dynamics. The performance of the techniques is shown in examples. The results are discussed and further research is outlined.
Using of building information modeling for existing buildings assessment
Authors: Garyaev Nikolay , Ayoub Fadi
Published: May 2021

The use BIM technology for new buildings have been proving his efficiency since the technology had established, the efficiency in costs estimation, construction management, resource saving incresed the interest to use BIM for existing building. The researchers covered a wide range of potential benefits for BIM in existing buildings such as: Facilities management, restoration and retrofit planning, deconstruction process, assessment and monitoring, maintenance and energy efficiency. In this paper the use of BIM for estimating the degree of physical deterioration is covered, based on the method included in the literature in Russian federation.
Modernization of telecommunication networks on the basis of studying demographic processes using GIS
Authors: Narbaev Sharafatdin , Abdurahmanov Sarvar , Allanazarov Olimjon , Talgatovna Albina , Aslanov Ilhomjon
Published: May 2021

The article studies and analyzes the geographical position of households, educational institutions, enterprises and organizations in settlements of the southern region of the Republic of Uzbekistan and their exact number in order to provide the population with telecommunication networks and Internet systems in the republic, as well as to improve the efficiency of fiber-optic cables. We have developed a special methodology for the analysis and study of demographic processes, consisting of six stages, based on cartographic methods. On their basis, a large-scale digital electronic sitemap was created using data from the State Statistics Committee.