Direct Construction Research Articles

3D-Bioprinting for Precision Microtissue Engineering: Advances, Applications, and Prospects.

Microtissues, engineered to emulate the complexity of human organs, are revolutionizing the fields of regenerative medicine, disease modelling, and drug screening. Despite the promise of traditional microtissue engineering, it has yet to achieve the precision required to fully replicate organ-like structures. Enter 3D bioprinting, a transformative approach that offers unparalleled control over the microtissue's spatial arrangement and mechanical properties. This cutting-edge technology enables the detailed layering of bioinks, crafting microtissues with tissue-like 3D structures. It allows for the direct construction of organoids and the fine-tuning of the mechanical forces vital for tissue maturation. Moreover, 3D-printed devices provide microtissues with the necessary guidance and microenvironments, facilitating sophisticated tissue interactions. The applications of 3D-printed microtissues are expanding rapidly, with successful demonstrations of their functionality in vitro and in vivo. This technology excels at replicating the intricate processes of tissue development, offering a more ethical and controlled alternative to traditional animal models. By simulating in vivo conditions, 3D-printed microtissues are emerging as powerful tools for personalized drug screening, offering new avenues for pharmaceutical development and precision medicine.

Constructing the internal Voronoi diagram of a polygonal figure using the sweep method

The article considers the problem of constructing the internal Voronoi diagram of a polygonal figure – a polygon with polygonal holes. A method based on the flat sweeping paradigm is proposed. Direct construction of only the internal part of the Voronoi diagram allows us to reduce the amount of calculations and increase robustness compared to known solutions. Another factor in reducing computational complexity is the use of the property of pairwise incidence of linear segments formed by the sides of a polygonal figure. To take these features into account, it is proposed to build the data structure Status of the sweeping line in the form of an ordered set of sites’ areas of responsibility. The structure is implemented as a combination of a balanced tree and a bidirectional list. Computational experiments illustrate the numerical reliability and efficiency of the proposed method.

Automated Parametrization Approach for Coarse-Graining Soil Organic Matter Molecules.

Investigating the molecular structure of soil organic matter (SOM), along with its intramolecular interactions and interactions with other soil components and xenobiotics, is essential due to its ecological importance. However, the complexity and heterogeneity of SOM present significant challenges for systematic studies. While experimental methods are commonly employed, atomistic simulations provide a complementary approach to exploring molecular-level processes. The Vienna Soil Organic Matter Modeler 2 (VSOMM2) facilitates the construction of molecular models of SOM systems with various compositions at the atomistic scale, which can then be examined through molecular dynamics (MD) simulations. This study introduces a parametrization strategy that enables the conversion of VSOMM2-generated structures into a coarse-grained representation, thus allowing larger time and length scales to be explored. By employing a conformer search technique, direct construction and analysis of coarse-grained SOM models with diverse compositions were made possible, eliminating the need for atomistic MD simulations. To demonstrate this approach, coarse-grained SOM models were created based on selected samples from the International Humic Substances Society, considering different water content levels for each model. Comprehensive analyses, including density and potential energy profile calculations, revealed a partial correlation with the SOM compositions and demonstrated that electrostatic interactions govern the structural packing. Moreover, a local phase separation process, particularly the formation of SOM voids, was observed over several microseconds, underscoring the advantages of the coarse-graining technique.

Ligand‐Tuning Metallic Sites in Molecular Complexes for Efficient Water Oxidation

Metal‐organic hybrid catalysts with highly tunable single‐sites are promising for oxygen‐evolution reaction (OER), but molecular‐scale understanding of underlying reaction mechanisms still remain elusive on these bulk materials. Herein, we report a direct construction of heterogenized molecular complexes stabilized on carbon substrates via coordinating Fe‐Ni sites with four aromatic carboxylate ligands (FeNi‐Lx). The ligands‐tuning π‐π stacking interaction between aromatic carboxylate ligands and carbon supports promote the oxidative charge accumulation on Fe‐Ni sites via fast electron transferring, thus the optimized FeNi‐Lx rendering a mass activity of 6680 A gFe/Ni‐1 at 0.3 V overpotential. In situ characteristics and theoretical analysis demonstrate that the OH‐ nucleophilic attack on hypervalent iron sites induce the reconstruction of active Fe‐O‐Ni species, accompanying with fast valence increasing. Whereas, during OER, the unexpected valence reduction of Fe‐O‐Ni sites would be attributed to the oxygen‐generating from OOH* intermediates. These findings would establish an essential understanding of the origin of active centers in molecular complexes catalysts for oxygen‐evolution.

Ligand-Tuning Metallic Sites in Molecular Complexes for Efficient Water Oxidation.

Metal-organic hybrid catalysts with highly tunable single-sites are promising for oxygen-evolution reaction (OER), but molecular-scale understanding of underlying reaction mechanisms still remain elusive on these bulk materials. Herein, we report a direct construction of heterogenized molecular complexes stabilized on carbon substrates via coordinating Fe-Ni sites with four aromatic carboxylate ligands (FeNi-Lx). The ligands-tuning π-π stacking interaction between aromatic carboxylate ligands and carbon supports promote the oxidative charge accumulation on Fe-Ni sites via fast electron transferring, thus the optimized FeNi-Lx rendering a mass activity of 6680 A gFe/Ni-1 at 0.3 V overpotential. In situ characteristics and theoretical analysis demonstrate that the OH- nucleophilic attack on hypervalent iron sites induce the reconstruction of active Fe-O-Ni species, accompanying with fast valence increasing. Whereas, during OER, the unexpected valence reduction of Fe-O-Ni sites would be attributed to the oxygen-generating from OOH* intermediates. These findings would establish an essential understanding of the origin of active centers in molecular complexes catalysts for oxygen-evolution.

Stochastic integration respect a cylindrical martingale-Lévy process with second moments

Abstract In this work we present an easy and direct construction of a Stochastic integral respect a cylindrical martingale-Lévy process. To do this, we apply the radonification technique. The radonification technique has been very useful to define an genuine stochastic process starting from a cylindrical process combine with Hilbert–Schmidt operators. With this work we present a self-contained construction, easy to follow to understand this new integration theories that are getting strong nowadays.

Cost Performance Comparison of Road Construction Projects Considering Bidding Condition and Project Characteristics

Developing road infrastructure facilities is important because it directly affects national competitiveness and has significant socio-economic ripple effects throughout the country. However, road construction projects are vulnerable to various risks and prone to cost overruns because they are funded by large-scale national budgets and conducted over long time periods. Therefore, tracking the changes in construction costs from planning to completion and providing insights for similar future projects is essential for successful project planning and management. Considering the bidding conditions and project characteristics of road construction projects, this study comparatively analyzed the construction cost growth of 170 road construction projects based on the bid award rate and facility-specific project characteristics, such as construction type, contract method, facility capacity, and construction cost components. This study analyzed the differences in cost performance between various sample groups using non-parametric tests (Mann–Whitney U test and Kruskal–Wallis test), considering the non-normality of the collected sample. In addition, this study conducted multiple regression analysis to examine the causal relationship between all variables used in the analysis and cost performance and to identify critical factors. The results indicated that the construction cost growth of the group with a bid award rate of less than 70% was higher compared to that of other groups. Furthermore, the differences in construction cost growth based on project characteristics were more pronounced in the following groups: construction types (expansion/renovation and complex), contract method (long-term continuous), road length (≥7.5 km), % of bridge/tunnel length (<10%), construction cost (≤USD 100 mil.), % of direct construction cost (≥70%), and % of bridge/tunnel cost (both less and more than 50%). Furthermore, the regression model showed that % of direct construction cost, bid award rate, total road length, and contract method were shown to be critical factors in construction cost growth, which implies the importance of indirect cost management, PDS selection decisions that affect bid award rates, and risk management for complex projects from the perspective of construction cost growth management. These results empirically demonstrate that bidding conditions and project characteristics are key to understanding the pattern of construction cost growth in road construction projects. Hence, this study provides significant references that can be used by policy makers and clients to estimate cost buffers for future road projects.

Silyl Radical‐Participated Silylfunctionalization of Alkenes and Alkynes

AbstractAlkenes and alkynes are inexpensive and readily available basic chemicals. Silyl radical‐participated silylation of alkenes and alkynes provides a powerful tool for the direct construction of organosilicon compounds. Compared to hydrosilylation reactions, silylfunctionalization reactions are more attractive and advantageous in building diverse organosilicon compounds, which has led to their becoming a research focus in organic synthesis. Herein, we provide a comprehensive overview of recent advances in silyl radical‐participated silylfunctionalization of alkenes and alkynes.

Group frames via magic states with applications to SIC-POVMs and MUBs

We connect magic (non-stabilizer) states, symmetric informationally complete positive operator valued measures (SIC-POVMs), and mutually unbiased bases (MUBs) in the context of group frames, and study their interplay. Magic states are quantum resources in the stabilizer formalism of quantum computation. SIC-POVMs and MUBs are fundamental structures in quantum information theory with many applications in quantum foundations, quantum state tomography, and quantum cryptography, etc. In this work, we study group frames constructed from some prominent magic states, and further investigate their applications. Our method exploits the orbit of discrete Heisenberg–Weyl group acting on an initial fiducial state. We quantify the distance of the group frames from SIC-POVMs and MUBs, respectively. As a simple corollary, we reproduce a complete family of MUBs of any prime dimensional system by introducing the concept of MUB fiducial states, analogous to the well-known SIC-POVM fiducial states. We present an intuitive and direct construction of MUB fiducial states via quantum T-gates, and demonstrate that for the qubit system, there are twelve MUB fiducial states, which coincide with the H-type magic states. We compare MUB fiducial states and SIC-POVM fiducial states from the perspective of magic resource for stabilizer quantum computation. We further pose the challenging issue of identifying all MUB fiducial states in general dimensions.

Research on the microscopic mechanism and model applicability differences of CH4 and CO2 adsorption based on molecular dynamics

To verify the accuracy and rationality of the molecular simulation model, the microscopic mechanism of gas adsorption was analyzed and clarified from a microscopic perspective. The effect of molecular models created by direct construction and supercell expansion on the adsorption capacities of CH4 and CO2 has been analyzed. Eight coal-based molecular configurations were created to simulate the isothermal adsorption process of CH4 and CO2 using various coal-based molecular configurations. Using physical experiments, the validity of different construction methods for coal-based molecular structures was verified. The direct construction method was chosen to simulate the effect of various coal-based molecular numbers on the adsorption capacity of CH4 and CO2. The results show that the adsorption capacity of CO2 on coal is greater than that of CH4. The isothermal adsorption curves of CH4 and CO2 in coal-based molecular systems constructed using different methods reveal that the adsorption of methane on coal molecules adheres to the Langmuir monolayer adsorption theory. The adsorption sites for methane increase with the rise in free volume. The structure directly constructed and the supercell expansion directly determines the amount of methane adsorbed by each coal based molecule. The adsorption constants of CH4 and CO2 on the supercell extended structure are more volatile than those on the directly constructed structure, and the structure constructed directly for different coal based molecules is better than the supercell extended structure. The simulation using the direct construction method shows that as the number of coal-based molecules in the molecular configuration increases, The isothermal adsorption quantities of CH4 and CO2 increase linearly. The molecular configuration is not affected by the number of anthracite molecules. Molecular configuration is not affected by the number of anthracite molecules. The rationality of model construction has no obvious relationship with the number of coal based molecules.

Catalytic N‐Formylation of CO2 by Atomically Precise Au8Pd1(DPPF)42+ Clusters into a Two‐Dimensional Metal–Organic Framework

AbstractBy highly efficient ligand‐exchange strategy, atomically precise Au8Pd1(PPh3)82+ (PPh3=triphenylphosphine) cluster can be transformed into a Au8Pd1(DPPF)42+ (DPPF=1,1′‐bis(diphenylphosphino)ferrocene) cluster that can maintain the atomic‐packing structure but overcome the lability of Au8Pd1(PPh3)82+. Catalytic evaluation for the CO2 hydrogenation coupled with o‐phenylenediamine demonstrates that the Au8Pd1(DPPF)42+ catalyst can remarkably enhance both activity and stability compared to the Au8Pd1(PPh3)82+ catalyst. More notably, the direct construction of a two‐dimensional metal–organic framework (2D MOF) can be elaborately accomplished in the formylation process of o‐phenylenediamine, CO2 and H2 with zinc nitrate enabled by the Au8Pd1(DPPF)42+ catalyst. The 2D MOF further enables the capture and transformation of CO2 to combine in the organic synthesis with epoxides under mild conditions. This work provides opportunities for creating highly active cluster sites for the chemical recycling of CO2.

Acidic Extracellular pH-Activated Allosteric DNA Nanodevice for Fluorescence Imaging of APE1 Activity in Tumor Cells.

Allostery is a phenomenon where the binding of a ligand at one allosteric site influences the affinity for another ligand at an active site. Different from orthosteric regulation, it allows for more precise control of biomolecular activity and enhances the stability of the molecules. Inspired by allosteric regulation of natural molecules, we present a Y-shaped allosteric DNA nanodevice, termed YssAP, that was pH-responsive and functionalized with the AS1411 aptamer for accurate fluorescence imaging of human apurinic/apyrimidinic endonuclease (APE1) activity in tumor cells. With rational design, YssAP could not be cut by APE1, and Cy5 was in the proximity of BHQ2, leading to suppressed signal emission. In contrast, since acidic pH acted as an allosteric effector, YssAP underwent a conformational change into an activated DNA probe (YdsAP) at acidic extracellular pH. After entering the tumor cell via the specific recognition of AS1411 aptamer, the overexpressed APE1 in the tumor cell cut the AP site on YdsAP. Cy5 moved far away from BHQ2, resulting in a strong signal output. Compared with the direct construction of the APE1 substrate, allosteric DNA nanodevices have more accurate imaging effects, which can be precisely adjusted by changing the switching state. We anticipate that this strategy will be applied in the screening of APE1 inhibitors and precise tumor diagnosis.

Catalytic N-Formylation of CO2 by Atomically Precise Au8Pd1(DPPF)4 2+ Clusters into a Two-Dimensional Metal-Organic Framework.

By highly efficient ligand-exchange strategy, atomically precise Au8Pd1(PPh3)8 2+ (PPh3=triphenylphosphine) cluster can be transformed into a Au8Pd1(DPPF)4 2+ (DPPF=1,1'-bis(diphenylphosphino)ferrocene) cluster that can maintain the atomic-packing structure but overcome the lability of Au8Pd1(PPh3)8 2+. Catalytic evaluation for the CO2 hydrogenation coupled with o-phenylenediamine demonstrates that the Au8Pd1(DPPF)4 2+ catalyst can remarkably enhance both activity and stability compared to the Au8Pd1(PPh3)8 2+ catalyst. More notably, the direct construction of a two-dimensional metal-organic framework (2D MOF) can be elaborately accomplished in the formylation process of o-phenylenediamine, CO2 and H2 with zinc nitrate enabled by the Au8Pd1(DPPF)4 2+ catalyst. The 2D MOF further enables the capture and transformation of CO2 to combine in the organic synthesis with epoxides under mild conditions. This work provides opportunities for creating highly active cluster sites for the chemical recycling of CO2.

Direct constructions of column-orthogonal strong orthogonal arrays

Strong orthogonal arrays have better space-filling properties than ordinary orthogonal arrays for computer experiments. Strong orthogonal arrays of strengths two plus, two star and three minus can improve the space-filling properties in low dimensions and column orthogonality plays a vital role in computer experiments. In this paper, we use difference matrices and generator matrices of linear codes to present several constructions of column-orthogonal strong orthogonal arrays of strengths two plus, two star, three minus and t. Our constructions can provide larger numbers of factors of column-orthogonal strong orthogonal arrays of strengths two plus, two star, three minus and t than those in the existing literature, enjoy flexible run sizes. These constructions are convenient, and the resulting designs are good choices for computer experiments.

SHRM Dimensions, Work Engagement and Intention to Quit: LinkedIn As a Data Source

The purpose of this study is to investigate the impact of strategic human-resource management (SHRM) on employees' intention to quit, mediated by work engagement in the construction sector in GCC countries. The major findings of this study indicate that strategic human-resource management (SHRM) has a direct positive impact on work engagement and an indirect negative impact on employees' intention to quit through work engagement. The study also indicated that work engagement has a direct negative impact on employees' intention to quit. Structural equation modeling was employed to analyze data collected from 612 participants via a LinkedIn dataset. All participants work in the construction sector in Gulf States (GCC countries) and are members at LinkedIn as a professional social-networking site. Social-media network LinkedIn was employed to collect the data required for analysis. The study offers evidence and guidance for HRM practitioners for direct HRM practices and SHRM constructs in fostering work engagement and managing employees’ intention to quit. There is a lack of research examining the impact of SHRM and its components on employees’ intention to quit, mediated by work engagement. Thus, this study confirms the argument that SHRM can be an effective approach to influence employees' intention to quit through work engagement.

Nestings of BIBDs with block size four

AbstractIn a nesting of a balanced incomplete block design (or BIBD), we wish to add a point (the nested point) to every block of a ‐BIBD in such a way that we end up with a partial ‐BIBD. In the case where the partial ‐BIBD is in fact a ‐BIBD, we have a perfect nesting. We show that a nesting is perfect if and only if . Perfect nestings were previously known to exist in the case of Steiner triple systems (i.e., ‐BIBDs) when , as well as for some symmetric BIBDs. Here we study nestings of ‐BIBDs, which are not perfect nestings. We prove that there is a nested ‐BIBD if and only if , . This is accomplished by a variety of direct and recursive constructions.

Enantioselective iridium-catalyzed allylic substitution with a Reformatsky reagent: direct construction of β-stereogenic homoallylic esters

Enantioselective iridium-catalyzed allylic substitution with a Reformatsky reagent: direct construction of β-stereogenic homoallylic esters

Direct construction of imidazoles via oxidative C(sp3)–H amination and annulation of aryethylamines by a Single-Atom cobalt catalyst

The development of reusable catalytic systems for achieving site-selective functionalization of C(sp3)-H bond remains a significant challenge. Herein, we designed a modified metal–organic framework (MOF)-derived N, P co-doped carbon supported single-atom cobalt catalyst, which was successfully applied in oxidative C(sp3)–H amination and cyclization of aryethylamines for construction of polysubstituted imidazoles. The advantages of the present method include: broad substrate scope, recyclable base metal catalyst, and naturally abundant O2 as green oxidant. The structural − activity relationship of the catalyst indicated that the atomically dispersed CoN3P1 is the active species responsible for the catalytic process. Furthermore, the synthesized imidazoles exhibited exceptional insecticidal activity against wheat pests, and may become lead molecules in the development of novel agricultural pesticide candidates, with significant application potential.

Desulfonation-associated direct amide bond formation between N-sulfonyl-1,2,3-triazoles with carboxylic acids

We have developed a highly N2-regioselective method for direct construction of amide bond from N-sulfonyl-1,2,3-triazoles and carboxylic acids in the presence of bases at 60 °C in air. The developed reaction provides the corresponding products with high yields (up to 90 %) and a broad substrate compatibility including aryl acids, heterocyclic acids, and alkyl acids. Mechanistic studies show that the reaction proceeds through a direct nucleophilic attack of N-sulfonyl-1,2,3-triazoles to carboxylate anions via a base- and water-involved synergistic desulfonation process. This work presents an unusual water-involved example for direct synthesis of amides utilizing readily available starting materials under mild conditions.

Accurate Simulation of Efimov Physics in Ultracold Atomic Gases with Realistic Three-Body Multichannel Interactions

We give a detailed and self-contained description of a recently developed theoretical and numerical method for the simulation of three identical bosonic alkali-metal atoms near a Feshbach resonance, where the Efimov effect is induced. The method is based on a direct construction of the off-shell two-body transition matrix from exact eigenfunctions of the embedded two-body Hamiltonians, obtained using realistic parameterizations of the interaction potentials which accurately reproduce the molecular energy levels. The transition matrix is then inserted into the appropriate three-body integral equations, which may be efficiently solved on a computer. We focus especially on the power of our method in including rigorously the effects of multichannel physics on the three-body problem, which are usually accounted for only by various approximations. We demonstrate the method for 7Li, where we recently showed that a correct inclusion of this multichannel physics resolves the long-standing disagreement between theory and experiment regarding the Efimovian three-body parameter. We analyze the Efimovian enhancement of the three-body recombination rate on both sides of the Feshbach resonance, revealing strong sensitivity to the spin structure of the model thus indicating the prevalence of three-body spin-exchange physics. Finally, we discuss an extension of our methodology to the calculation of three-body bound-state energies.