Critical Role Research Articles

Leading in times of crisis and remote work: perceived consideration leadership behavior and its effect on follower work engagement

Based on the job-demands resources theory, we examine whether leadership behavior affects followers' work engagement in the context of remote work during times of crisis, and how this effect can be explained. We focus on consideration leadership and its impact on followers' engagement under conditions of enforced remote work during the COVID-19 pandemic. Therein, we examine the role of optimism as a potential mediator. To better understand how the impact of consideration leadership behavior unfolds during crises, we examine whether being new to remote work and feeling personally impacted by COVID-19 amplified the proposed relationship between consideration leadership and followers' engagement. A sample of 729 German employees participated in a three-wave study across 6 weeks in May and June 2020. Longitudinal structural equation modeling uncovered direct positive effects of consideration leadership on changes in followers' work engagement in the second time lag (T2 to T3), while optimism did not mediate this effect. Multigroup comparisons revealed that employees who worked from home were particularly responsive to consideration leadership. No moderating effects were found for whether the COVID-19 pandemic personally impacted employees. The discussion highlights the critical role of leadership in followers' motivation and wellbeing in times of crisis and remote work.

O3‐Type Cathodes for Sodium‐Ion Batteries: Recent Advancements and Future Perspectives

AbstractOver recent decades, rapid advancements in energy technology have transformed human life. Lithium‐ion batteries (LIBs) have played a pivotal role nevertheless concerns about limited lithium resources and price fluctuations underscore the need for sustainability. Sodium‐ion batteries (SIBs), operating on principles akin to LIBs, have emerged as promising candidates for rechargeable batteries in the next generation of energy storage systems, primarily due to their cost‐effectiveness and sustainable attributes. Analogous to LIBs, the cathode in SIBs assumes a critical role in dictating the electrochemical performance of the battery. Therefore, the research and development of cathode materials for SIBs take on paramount significance. O3‐type SIB cathodes, inspired by the successful O3‐type LIB cathodes (e. g., LiCoO2 and NMC variants), hold promise for commercial applications. This comprehensive overview offers an in‐depth exploration of various unary‐metal oxide cathode materials characterized by an O3‐layered structure. Subsequently, nickel (Ni), manganese (Mn), and Ni/Mn‐based O3 cathode materials are conducted a comprehensive study, assessing the effects of element substitution and doping on capacity, phase transitions, and cycle life. In light of the current challenges, advancing SIB cathode materials of future directions will propose, addressing key considerations in the pursuit of enhanced performance and sustainable energy storage solutions.

Lipoteichoic acids influence cell shape and bacterial division of Streptococcus suis serotype 2, but play a limited role in the pathogenesis of the infection

Streptococcus suis serotype 2 is a major swine pathogen and a zoonotic agent, causing meningitis in both swine and humans, responsible for substantial economic losses to the swine industry worldwide. The pathogenesis of infection and the role of bacterial cell wall components in virulence have not been fully elucidated. Lipoproteins, peptidoglycan, as well as lipoteichoic acids (LTA) have all been proposed to contribute to virulence. In the present study, the role of the LTA in the pathogenesis of the infection was evaluated through the characterisation of a mutant of the S. suis serotype 2 strain P1/7 lacking the LtaS enzyme, which mediates the polymerization of the LTA poly-glycerolphosphate chain. The ltaS mutant was confirmed to completely lack LTA and displayed significant morphological defects. Although the bacterial growth of this mutant was not affected, further results showed that LTA is involved in maintaining S. suis bacterial fitness. However, its role in the pathogenesis of the infection appears limited. Indeed, LTA presence reduces self-agglutination, biofilm formation and even dendritic cell activation, which are important aspects of the pathogenesis of the infection caused by S. suis. In addition, it does not seem to play a critical role in virulence using a systemic mouse model of infection.

Role of Microtubule Network in the Passive Anisotropic Viscoelasticity of Healthy Right Ventricle.

Cardiomyocytes are viscoelastic and key determinants of right ventricle (RV) mechanics. Intracellularly, microtubules are found to impact the viscoelasticity of isolated cardiomyocytes or trabeculae; whether they contribute to the tissue-level viscoelasticity is unknown. Our goal was to reveal the role of the microtubule network in the passive anisotropic viscoelasticity of the healthy RV. Equibiaxial stress relaxation tests were conducted in healthy RV free wall (RVFW) under early (6%) and end (15%) diastolic strain levels, and at sub- and physiological stretch rates. The viscoelasticity was assessed at baseline and after the removal of microtubule network. Furthermore, a quasi-linear viscoelastic (QLV) model was applied to delineate the contribution of microtubules to the relaxation behavior of RVFW. After removing the microtubule network, RVFW elasticity and viscosity were reduced at the early diastolic strain level and in both directions. The reduction in elasticity was stronger in the longitudinal direction, whereas the degree of changes in viscosity were equivalent between directions. There was insignificant change in RVFW viscoelasticity at late diastolic strain level. Finally, the modeling showed that the tissue's relaxation strength was reduced by the removal of the microtubule network, but the change was present only at a later time scale. These new findings suggest a critical role of cytoskeleton filaments in RVFW passive mechanics in physiological conditions.

PAK1 Promotes Inflammation Induced by Sepsis through the Snail/CXCL2 Signaling Pathway.

Sepsis is a severe syndrome characterized by organ dysfunction, resulting from a systemic imbalance in response to infection. PAK1 plays a critical role in various diseases. The present study aimed to explore and delineate the mechanism of PAK1 in inflammation induced by sepsis. Bioinformatics analysis was performed to assess PAK1, snail, and CXCL2 expression in the whole blood of septic patients and the pathways enriched with PAK1. To simulate the sepsis model, THP-1 cells were stimulated with lipopolysaccharide. Gene expression was evaluated using qRT-PCR, while cell viability was assessed using CCK-8 assay. Cell apoptosis was tested with flow cytometry. Expression of inflammatory factors in cells following different treatments was analyzed using the enzyme linked immunosorbent assay (ELISA). Dual-luciferase and chromatin immunoprecipitation assays were conducted to verify the binding relationship between PAK1 and the snail. Mouse models of cecal ligation and puncture were established, and hematoxylin and eosin staining and ELISA were employed to detect the infiltration levels of inflammatory cells and the expression of related protective factors in lung, liver, and kidney tissues. The results demonstrated upregulation of PAK1, snail, and CXCL2 in the whole blood of septic patients, with PAK1 being enriched in the chemokine-related pathway. Knockdown of PAK1 significantly promoted the apoptosis of LPS-stimulated THP-1 cells and inhibited the expression of inflammatory factors. PAK1 upregulated the expression of the snail, which in turn promoted the expression of CXCL2. Thus, PAK1 mediated the sepsis-induced inflammatory response through the snail/CXCL2 pathway. In conclusion, PAK1 played a role in promoting inflammation induced by sepsis through the snail/CXCL2 axis, thereby providing a potential therapeutic target for the management of sepsis.

Environment-driven evolution analysis of a product: A case study of braking system evolution

In response to evolving societal and technical demands, this research explores the dynamic landscape of product evolution, focusing on the case study of braking systems. Acknowledging the critical role of product evolution analysis in design phases, the study introduces the Environment-Based Design (EBD) methodology. EBD emphasizes environmental analysis before delving into product specifics, employing tools like Recursive Object Model (ROM) diagrams and questioning-and-answering analyses. The paper systematically unfolds with a literature review highlighting various design methodologies, followed by the EBD application in a braking system evolution analysis. Trends in environment components are dissected, emphasizing the increasing influence of the human environment. The discussion underlines the significance of analyzing environment components in product evolution and asserts EBD’s applicability. Despite limitations, such as the exclusive focus on braking systems, the study contributes to understanding product evolution dynamics and advocates for the continued exploration of EBD across diverse products and cultural contexts.

Highly pathogenic PRRSV upregulates IL-13 production through nonstructural protein 9–mediated inhibition of N6-methyladenosine demethylase FTO

Porcine reproductive and respiratory syndrome virus (PRRSV), a highly infectious and causes severe losses in the swine industry by regulating the inflammatory response, inducing tissue damage, suppressing the innate immune response, and promoting persistent infection in hosts. Interleukin-13 (IL-13) is a cytokine that plays a critical role in regulating immune responses and inflammation, particularly in immune-related disorders, certain types of cancer, and numerous bacterial and viral infections; however, the underlying mechanisms of IL-13 regulation during PRRSV infection are not well understood. In this study, we demonstrated that PRRSV infection elevates IL-13 levels in porcine alveolar macrophages (PAMs). PRRSV enhances m6A methylated RNA levels while reducing the expression of fat mass and obesity associated protein (FTO, an m6A demethylase), thereby augmenting IL-13 production. PRRSV nonstructural protein 9 (nsp9) was a key factor for this modulation. Furthermore, we found that the residues Asp567, Tyr586, Leu593, and Asp595 were essential for nsp9 to induce IL-13 production via attenuation of FTO expression. These insights delineate PRRSV nsp9's role in FTO-mediated IL-13 release, advancing our understanding of PRRSV's impact on host immune and inflammatory responses.

Corneal Neurotization: Essentials for The Facial Paralysis Surgeon.

Deficits in corneal innervation lead to neurotrophic keratopathy (NK). NK is frequently associated with facial palsy, and corneal damage can be accelerated by facial palsy deficits. Corneal nerves are important regulators of limbal stem cells, which play a critical role in epithelial maintenance and healing. Nonsurgical treatments of NK have undergone recent innovation, and growth factors implicated in corneal epithelial renewal are a promising therapeutic avenue. However, surgical intervention with corneal neurotization (CN) remains the only definitive treatment of NK. CN involves the transfer of unaffected sensory donor nerve branches to the affected cornea, and a variety of donor nerves and approaches have been described. CN can be performed in a direct or indirect manner; employ the supraorbital, supratrochlear, infraorbital, or great auricular nerves; and utilize autograft, allograft, or nerve transfer alone. Unfortunately, comparative studies of these factors are limited due to the procedure's novelty and varied recovery timelines after CN. Regardless of the chosen approach, CN has been shown to be a safe and effective procedure to restore corneal sensation and improve visual acuity in patients with NK.

Non‐turbulent motion identified from properties of transport and its influence on the calculation of turbulent flux

AbstractTurbulent fluxes play a critical role in atmospheric science and are usually calculated from the eddy covariance system. However, the presence of motions of larger scale and the bias from observational instruments often affects the procurement of turbulent fluxes. Based on the Hilbert–Huang transform, the properties of transport can be defined and used to distinguish non‐turbulent motions from the observational data, and a new way of decomposing the variables is thereby put forward to reconstruct the turbulent flux series. To quantify the influence of non‐turbulent motions on the calculation of turbulent flux, the non‐turbulent motions extracted from the five‐level turbulence data of the Tianjin 255‐m meteorological tower from July 1 to August 31, 2017 are examined. The results reveal that the presence of non‐turbulent motion can lead to a universal overestimation of turbulent flux, and the degree of overestimation increases with the complexity and the intensity of non‐turbulent motion. According to the consequences above, an empirical relationship, together with the corresponding coefficients, is given to provide a guidance on the correction of turbulent fluxes in practical use, such as the simulation of atmospheric turbulence and the parameterization in meteorological and climate models.

Mechanism study of ubiquitination in T cell development and autoimmune disease.

T cells play critical role in multiple immune processes including antigen response, tumor immunity, inflammation, self-tolerance maintenance and autoimmune diseases et. Fetal liver or bone marrow-derived thymus-seeding progenitors (TSPs) settle in thymus and undergo T cell-lineage commitment, proliferation, T cell receptor (TCR) rearrangement, and thymic selections driven by microenvironment composed of thymic epithelial cells (TEC), dendritic cells (DC), macrophage and B cells, thus generating T cells with diverse TCR repertoire immunocompetent but not self-reactive. Additionally, some self-reactive thymocytes give rise to Treg with the help of TEC and DC, serving for immune tolerance. The sequential proliferation, cell fate decision, and selection during T cell development and self-tolerance establishment are tightly regulated to ensure the proper immune response without autoimmune reaction. There are remarkable progresses in understanding of the regulatory mechanisms regarding ubiquitination in T cell development and the establishment of self-tolerance in the past few years, which holds great potential for further therapeutic interventions in immune-related diseases.

The Mediating Role of Emotional Arousal and Donation Anxiety on Blood Donation Intentions: Expanding on the Theory of Planned Behavior.

Blood donation is essential in health-care systems worldwide, dealing with the demand for transfusions, and for the treatment of a variety of medical conditions. A major obstacle is raising the rate of blood donations by recruiting and retaining donors in an efficient manner. This paper presents a comprehensive analysis of blood donation, utilizing an enhanced framework based on the theory of planned behavior with an emphasis on emotional arousal (positive and negative), attitudes towards advertisements, and blood donation anxiety, revealing critical psychological and communicative determinants of blood donation intention. To achieve this, a quantitative non-experimental correlational technique was employed to collect data from 414 individuals using an online questionnaire circulated across Greek society. The data were analyzed using structural equation modelling, with a focus on the direct impacts on donation intentions and the role of emotional arousal as a mediator. The findings indicate that attitudes and anxiety have strong direct impacts on the behavioral intention to donate, underlining the important barriers generated by donation anxieties as well as the efficacy of positive attitudes and successful advertising. Furthermore, the study demonstrates emotional arousal as a partial mediator, implying that both cognitive assessments and emotional responses play a role in influencing donation intentions. This study takes on a new approach to give emphasis and provide evidence of the mediating effect of emotional arousal on donation intention, utilizing structural equation modeling. Despite the critical role of marketing as a primary source of blood donors, the implementation of emotional marketing techniques has been one aspect less addressed throughout marketing professionals and communication efforts. Our results demonstrate the significance of emotional arousal on blood donation intentions, thus suggesting a more emotionally resonant approach of attracting potential donors.

SUSTAINABLE SMART CITIES: THE ROLE OF FINTECH IN PROMOTING ENVIRONMENTAL SUSTAINABILITY

Sustainable smart cities are at the forefront of urban development, striving to balance economic prosperity with environmental sustainability. This Review delves into the critical role played by Financial Technology (Fintech) in advancing environmental sustainability within smart city initiatives. Fintech innovations are instrumental in optimizing resource management, enhancing citizen engagement, and fostering collaborative governance models, thereby contributing to the overarching goal of creating sustainable urban ecosystems. Through a historical perspective, this Review traces the evolution of sustainable smart cities, highlighting the transformative impact of technological advancements and the integration of Fintech solutions. From early urban planning concepts to the emergence of smart technologies in the 21st century, the evolution of sustainable smart cities underscores the importance of leveraging innovation to address urban challenges. The rise of Fintech has further accelerated this evolution, offering innovative financial services tailored to support green finance, renewable energy investment, and sustainable infrastructure development. Fintech platforms enable efficient allocation of resources, facilitate transparent and secure transactions, and empower citizens to participate in sustainable initiatives. By integrating Fintech solutions into urban development strategies, cities can unlock new opportunities for environmental sustainability while fostering economic growth and social equity. Looking ahead, the integration of sustainable smart cities and Fintech holds immense potential to address pressing environmental challenges such as climate change, pollution, and resource depletion. As cities continue to embrace digital transformation and adopt data-driven approaches, the role of Fintech in promoting environmental sustainability will become increasingly crucial. By leveraging historical insights and embracing emerging technologies, cities can chart a path towards a more resilient, inclusive, and environmentally sustainable future. This Review underscores the importance of collaboration among stakeholders, including governments, businesses, academia, and civil society, to drive collective action and accelerate the transition towards sustainable smart cities.
 Keywords: Sustainable, Smart Cities, Fintech, Promoting, Environmental.

Vietnam's Long-run Growth: Connecting the Dots through Climate Damage Spillovers

We propose to examine how climate damage may transform Vietnam's long-run growth rate. Because of cross-country linkages forged by bilateral trade, there are two channels through which international damage spillovers may occur. First, the dynamics of partners' growth determine future trends in Vietnam's volume of exports. Second, since the domestic impact of climate change may be heterogeneous across countries, there will be a differentiated impact on export and import market shares. Both terms play a critical role in changing trade patterns that are likely to shift Vietnam's external constraint. This demand-side view of growth based on the balance-of-payments constraint is a powerful predictor of inter-country growth differences. Our study show that the consequences of climate change could equate to a 2.5% reduction in Vietnam's growth rate over the period 2020-2060. Our decomposition exercise by effect and by partner area shows that international damage spillovers result from very different individual behaviours.

Inflation adjustments of financial statements: Implication to price index and performance

This paper examines the critical role of inflation accounting in adjusting financial statements to accurately reflect the impact of inflation on the economy. The primary objectives are twofold: examine the process of restating balance sheets and income statements, emphasizing the limitations inherent in historical cost accounting; and investigate the practical usefulness of price indices in identifying complex changes in the value of monetary and non-monetary assets and liabilities. It uses a systematic analysis of the restatement process, delving into the application of the Constant Purchasing Power Accounting (CPPA) method. The study used Royal Dutch Airlines Company for the years 2018-2019 financial data, including varying different inflation levels. The results of the analysis reveal that indexing revenues under the CPPA method improves liquidity, profitability, and solvency ratios. This improvement is particularly evident in the cash flow statement analysis, where corrections are minimized compared to historical cost accounting. The CPPA method appears to be a powerful solution to the limitations imposed by historical costing in inflationary environments. It is worth noting that the research reveals differences in the practical application of inflation calculations between countries, depending on economic and regulatory factors. This paper calls for continued research efforts to delve deeper into the implications of inflation for different industries, economies and financial reporting frameworks.

Holistic dielectric and buffer interfacial layers enable high-efficiency perovskite solar cells and modules

Suppressing the interfacial non-radiative recombination plays a critical role in reducing the voltage loss of perovskite solar cells. Herein, we develop a holistic interfacial regulation using dielectric materials of Al2O3 and PEABr/PMMA, and a buffer layer of compact SnOX to manipulate the multiple interfaces. A compact SnOX is inserted to reduce the charge accumulation at the interface of electron transport layer/Ag. Through this multiple interfacial design, the power conversion efficiency is greatly increased from 22.66% to 25.70% (certified 24.23%), mainly attributing to much enhancement in open circuit voltage and fill factor. The fill factor of 86.41% is the highest among the self-assembled-monolayers-based inverted devices. Both perovskite film and resulting device show increased thermal stability due to the incorporation of compact SnOX, which inhibits the escape of volatile species from perovskite, infiltration of moisture and the suppression of ion migration. Scaling up this strategy delivers an efficiency for a minimodule as high as 21.56%. More importantly, we discovered that the PEABr passivation could induce the collapse of morphology under continuous illumination, thus leading to worse operational stability. This work provides a path towards omnibearing modification for minimizing the trap-assisted recombination at the interface through the synergetic effects of dielectric materials.

A Global Climatology of Diabatic Heating in Tropical Easterly Waves

Abstract Tropical easterly waves (TEWs) play a critical role in regulating convection and precipitation across the global tropics. TEWs act as seed disturbances for tropical cyclogenesis, serve as an essential component in monsoon precipitation, and produce large amounts of rainfall and diabatic heating that can strongly affect the large-scale circulation. To help improve our knowledge of a more elusive type of tropical wave, we use satellite and reanalysis estimates of the diabatic heating associated with TEWs that are identified by a tracking algorithm based on low-level curvature vorticity. This study uses the Tropical Rainfall Measuring Mission (TRMM) version 6 convective–stratiform heating (CSH) and spectral latent heating (SLH) orbital products to create a global climatology (1998–2015) of TEW diabatic heating. TEW-specific composites for the satellite-observed vertical structure of diabatic heating are compared to similar terms from MERRA-2 across a variety of tropical regions. There are striking differences between the reanalysis and satellite heating with MERRA-2 having much stronger background heating, especially at low levels. Both the satellite-observed and reanalysis heating profiles show stronger midlevel heating associated with TEWs relative to the unconditional background. Similar patterns of mid- and bottom-heaviness emerge in two-dimensional composites of TEW latent heating as stronger heating rates and percent contributions to the background are generally higher at 500 hPa than at 850 hPa. Although TEWs only represent a few percent of the background heating across the global tropics, they comprise 30%–50% of the heating in the prominent TEW tracks over the northeastern Atlantic and Pacific Oceans.

Critical Role of Aromatic C(sp2)-H in Boosting Lithium-Ion Storage.

Exploring high-sloping-capacity carbons is of great significance in the development of high-power lithium-ion batteries/capacitors (LIBs/LICs). Herein, an ion-catalyzed self-template method is utilized to synthesize the hydrogen-rich carbon nanoribbon (HCNR), achieving high specific and rate capacity (1144.2/471.8 mAh g-1 at 0.1/2.5 A g-1). The Li+ storage mechanism of the HCNR is elucidated by in situ spectroscopic techniques. Intriguingly, the protonated aromatic sp2-hybridized carbon (C(sp2)-H) can provide additional active sites for Li+ uptake via reversible rehybridization to sp3-C, which is the origin of the high sloping capacity. The presence of this sloping feature suggests a highly capacitance-dominated storage process, characterized by rapid kinetics that facilitates superior rate performance. For practical usage, the HCNR-based LIC device can deliver high energy/power densities of 198.3 Wh kg-1/17.9 kW kg-1. This work offers mechanistic insights on the crucial role of aromatic C(sp2)-H in boosting Li+ storage and opens up new avenues to develop such sloping-type carbons for high-performance rechargeable batteries/capacitors.

Applying the MIMO BP Neural Network and Cloud-Based Monitoring of Thermal Behavior for High-Speed Motorized Spindle Units

Understanding the temperature–working condition relationship is crucial for optimizing machining processes to ensure dimensional accuracy, surface finish quality, and overall spindle longevity. Monitoring and controlling spindle temperature through appropriate cooling systems and operational parameters are essential for efficient and reliable machining operations. This paper presents an in-depth analysis of the thermal equilibrium and deformation characteristics of a high-speed motorized spindle unit utilized in grinding machine tools. Through a series of thermal equilibrium experiments and meticulous data acquisition, the study investigates the nuanced influence of various working conditions, including spindle speeds, coolant types, and coolant flow rates, on spindle temperatures and thermal deformations. Leveraging the power of Artificial Neural Networks (ANNs), predictive models are meticulously developed to accurately forecast spindle behavior. Subsequently, the models are seamlessly transitioned to a cloud computing infrastructure to ensure remote accessibility and scalability, facilitating real-time monitoring and forecasting of spindle performance. The validity and reliability of the predictive models are rigorously assessed through comparison with experimental data, demonstrating excellent agreement and high accuracy in forecasting spindle thermal behavior. Furthermore, the study underscores the critical role of key working condition variables as precise predictors of spindle temperature and thermal deformation, emphasizing their significance in optimizing overall spindle efficiency and performance. This comprehensive analysis offers valuable insights and practical implications for enhancing spindle operation and advancing the field of grinding machine tools.

Electronic transport properties of WS2 using ensemble Monte Carlo method

The electronic transport characteristics of tungsten disulfide (WS2) sheets are studied using the ensemble Monte Carlo technique in the presence of intrinsic scattering mechanisms only. The transport properties of the material are obtained in a two-valley model where intra- and inter-valley scatterings are considered in K and Q valleys. The velocity overshoot effect is observed for some applied field values. Negative differential phenomena are seen for some values of the energy difference between K and Q valleys ( ΔEKQ ), therefore ΔEKQ and the effective mass of carriers in the Q valley has a critical role in the transport and mobility characteristics of WS2. The mobility of carriers is calculated as a function of temperature and the results are compatible with some existing theoretical and experimental predictions.

A Combination of Flexible Modified Plant Virus Nanoparticles Enables Additive Effects Resulting in Improved Osteogenesis.

Plant virus nanoparticles (VNPs) genetically engineered to present osteogenic cues provide a promising method for biofunctionalizing hydrogels in bone tissue engineering. Flexible Potato virus X (PVX) nanoparticles substantially enhance the attachment and differentiation of human mesenchymal stem cells (hMSCs) by presenting the RGD motif, hydroxyapatite-binding peptide (HABP), or consecutive polyglutamates (E8) in a concentration-dependent manner. Therefore, it is hypothesized that Tobacco mosaic virus nanoparticles, which present 1.6 times more functional peptides than PVX, will meliorate such an impact. This study hypothesizes that cultivating hMSCs on a surface coated with a combination of two VNPs presenting peptides for either cell attachment or mineralization can achieve additionally enhancing effects on osteogenesis. Calcium minerals deposited by differentiating hMSCs increases two to threefold for this combination, while the Alkaline Phosphatase activity of hMSCs grown on the PVX-RGD/PVX-HABP-coated surface significantly surpasses any other VNP combination. Superior additive effects are observed for the first time by employing a combination of VNPs with varying functionalities. It is found that the flexible VNP geometry plays a more critical role than the concentration of functional peptides. In conclusion, various peptide-presenting plant VNPs exhibit an additive enhancing effect offering significant potential for effectively functionalizing cell-containing hydrogels in bone tissue engineering.