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Low dimensional sp3 carbon nanostructures have attracted increasing attention recently, due to their unique properties and appealing applications. Based on in silico studies, this work exploits the impacts from functional groups on the tensile properties of carbon nanothreads (NTH) – a new sp3 carbon nanostructure. It is found that functional groups will alter the local bond configuration and induce initial stress concentration, which significantly reduces the fracture strain/strength of NTH. Different functional types lead to different local bond re-configurations, and introduce different impacts on NTH. Further studies reveal that the tensile properties decreases generally when the content of functional groups increases. However, some NTHs with higher content of functional groups exhibit higher fracture strain/strength than their counterparts with lower percentage. Such observations are attributed to the synergetic effects from the sample length, self-oscillation, and distribution of functional groups. Simulations show that the tensile behaviour of NTH with the same functional percentage differs when the distribution pattern varies. Overall, ethyl groups are found to induce larger degradation on the tensile properties of NTH than methyl and phenyl groups. This study provides a comprehensive understanding of the influence from functional groups, which should be beneficial to the engineering applications of NTH.

Low-dimensional nanostructures have been widely used as reinforcements for polymer nanocomposites. However, a majority of studies have considered the samples containing a single nanofiller or perfe...

The mechanical performance of nanomaterial-reinforced polymer nanocomposites is a prerequisite for their engineering implementations, which is largely determined by the interfacial load transfer efficiency. This work investigates the role of the nanofillers via molecular dynamics simulations under different deformation scenarios, mimicking a maximum and minimum load transfer scenario from the polymer matrix. On the basis of the polyethylene (PE) nanocomposite reinforced by a new nanofiller-carbon nanothread (NTH), we find that the loading conditions dominantly determine its enhancement effect on the mechanical properties of the PE nanocomposite. Under tensile deformation, the ultimate tensile strength of the PE nanocomposite receives around 61 to 211% increment when the filler deforms simultaneously with the PE matrix. However, such enhancement is largely suppressed when the NTH is deforming nonsimultaneously. Similar results are observed from the compressive deformation. Specifically, both morphology and functionalization are found to alter the enhancement effect from the NTH fillers, while also relying on the loading directions. Overall, this work provides an in-depth understanding of the role of the nanofiller. The observations signify the importance of establishing effective load transfer at the interface, which could benefit the design and fabrication of high-performance polymer nanocomposites.

Two-dimensional (2D) materials integrated with anisotropy and ferroelasticity are highly desired for controllable polarization-sensitive devices and ferroelastic memorizers but are rarely reported. Herein, using the particle swap optimization (PSO) method and first-principles calculations, we theoretically predicted the coexistence of single-direction auxeticity, anisotropic carrier mobility, and intrinsic ferroelasticity in 2D silver oxide (AgO). Linear and square–planar Ag–O ligands align vertically in 2D AgO, leading to remarkable in-plane anisotropy. 2D AgO exhibits a large out-of-plane negative Poisson's ratio (NPR) of −0.47 which can only be triggered by the uniaxial strain along the y-direction. The electrons/holes favor the transport along the x-direction with mobilities of up to ∼6000/4000 cm2 V−1 s−1, which is around 10/17 times higher than that along the y-direction. Moreover, a strain-driven 90° lattice rotation is found in 2D AgO with a record high reversal strain of 107.6%. Such integration allows us to tune the direction of the anisotropic properties, and at the same time enables the efficient identification of the bi-stable states during the ferroelastic transition, thus promising the versatile applications of 2D AgO in controllable mechanic/electronic devices and non-volatile information storage.

Polymer nanocomposites with high thermal conductivity have been increasingly sought after in the electronic industry. Based on molecular dynamics simulations, this work assesses the thermal transport in polyethylene (PE) nanocomposites with the presence of a new one-dimensional nanofiller-a carbon nanothread (NTH). It is found that the axial thermal conductivity of PE nanocomposites increases linearly with the content of regularly aligned NTH fillers, while the aggregated pattern suppresses the enhancement effect. This phenomenon is explained by a stronger filler-filler interaction that reduces the intrinsic thermal conductivity of the NTH. Results show that the randomly dispersed NTHs can hardly promote heat transfer because effective heat transfer channels are lacking. Strikingly, surface functionalization has an adverse effect on the thermal conductivity due to the presence of additional voids. The presence of voids answers a long-standing open question that functionalization of the heat conductive filler only slightly improves the thermal conductivity of the polymer composite. Additionally, the transverse thermal conductivity degrades in the presence of the NTH and exhibits no clear correlation with the filler content or the distribution pattern. Overall, this study provides an in-depth understanding of the heat transfer within the polymer nanocomposites, which opens up possibilities for the preparation of highly conductive polymers.

Three-dimensional (3D) printing technologies are widely applied in various industries and research fields and are currently the subject of intensive investigation and development. However, high-performance materials that are suitable for 3D printing are still in short supply, which is a major limitation for 3D printing, particularly for biomedical applications. The physicochemical properties of single constituent materials may not be sufficient to meet the needs of modern biotechnology development and production. To enhance the materials' performance and broaden their applications, this work designed and tested a series of titanate nanofiller (nanowire and nanotube)-enhanced polycaprolactone (PCL) composites that were 3D-printable and provided superior mechanical properties. By grafting two different functional groups (phenyl- and thiol-terminated ligands), the nanofiller surface showed improved hydrophobicity, which significantly improved their dispersion in the PCL matrix. After characterizing the surface modification, we evaluated the significance of the homogeneity of the ceramic nanofiller in terms of printability, formability, and mechanical strength. Melt electrowriting additive manufacturing was used to fabricate microfibers of PCL and PCL/nanofiller composites. Improved nanofiller dispersion enabled intact and uniform sample morphology, and in contrast, nanofiller aggregation greatly varied the viscosity during the printing process, which could result in poorly printed structures. Importantly, the modified ceramic/PCL composite delivered enhanced and stable mechanical properties, where its Young's modulus was measured to be 1.67 GPa, which is more than 7 times higher compared to that of pristine PCL (0.22 GPa). Retaining the cell safety properties (comparable to PCL), the concept of enhancing biocompatible polymers with modified nanofillers shows great potential in the field of customized 3D printing for biomedicine.

Chitosan has been considered attractive in polymer electrolyte membrane fuel cells (PEMFCs) due to its excellent film forming and fuel barrier properties. Reflecting the limitation of its low proton conductivity, various materials were used to improve the proton conductivity of chitosan, through combination with inorganic materials like graphene oxide. We present an ideal molecular model for bio-nanocomposites and their mechanism of proton conductivity in PEMFCs. In this study, the diffusion behavior of hydronium ions in chitosan/graphene complex systems at various temperatures, concentrations and pH values were studied systematically using 3 ns long molecular dynamics (MD) simulations with an aim to provide the mechanisms of proton conductivity of chitosan/graphene composite at an atomistic scale. Various amounts of water content (10%, 20%, 30% and 40%), pH values (achieved by adjusting the protonation degree of amino groups of chitosan by 20%, 40%, 60%, 80% and 100%) and numbers of graphene sheets (1, 2, and 3) were considered during MD simulations at 4 temperatures (298 K, 320 K, 340 K and 360 K). Our results indicated that the chitosan system containing 40% water was the most suitable polymer electrolyte membrane and temperature was a key factor affecting diffusion proton. Adding graphene to the chitosan system and adjusting the pH values of chitosan were demonstrated to have a significant effect on improving the proton conductivity of the membrane.

To ensure reliable performance and lifetime of electronics, effective and efficient heat removal is essential, which relies heavily on the high thermal conductivity of the packaging substrates and thermal interface materials (TIMs). Highly conductive fillers have been commonly applied to enhance the thermal conductivity of TIMs, while the enhancement effect has been significantly impeded by the interfacial thermal resistance. This work reveals that the new type of ultra-thin carbon nanomaterial – carbon nanothreads, possess a much smaller interfacial thermal resistance (3.1 ± 0.4 × 10−9 Km2/W) between each other compared with that of the (4,0) carbon nanotubes (8.8 ± 4.6 × 10−9 Km2/W). Similar as found for carbon nanotubes, the interfacial thermal resistance decreases when the interfacial crossing angle decreases or the contact area increases. Surprisingly, both compressive and stretching interfacial distance are found to enhance the interfacial thermal conductance. It is found that different carbon nanothreads exhibit an interfacial thermal conductance between 60 and 110 pW/K, which can be remarkably enhanced by introducing interfacial cross-linkers. Combining with the ultra-thin nature of carbon nanothreads, our work suggests that carbon nanothreads can be an excellent alternative nanofillers for polymer composites with enhanced thermal conductivity.

Targeted tumor imaging in vivo has been one of the main challenges in the early stage of cancer diagnosis and therapy. However, few contrast probes are available to specifically respond to tumor environments. The aim was to investigate porphyrin-1,8-naphthalimide derivative (APTSPP-2NI) as a potential tumor-targeting fluorescent probe in vitro and in vivo. A tumor-targeting APTSPP-2NI was synthesized by the incorporation of water-soluble 5-(4’-aminophenyl)-10,15,20-tris(4’-sulfonato-phenyl) porphyrin (APTSPP) as a tumor-targeting group into N-butyl-4-ethyldiamino-1,8-naphthalene imide (NI) fluorescence molecule herein. The derivative was further characterized and its properties in vitro and in vivo including the cell cytotoxicity, cell uptake of tumor cells and fluorescent imaging were also evaluated. Experiment results indicated that APTSPP-2NI possessed the low cell cytotoxicity and good tumor-targeting property to the B16F10 melanoma cells. Moreover, APTSPP-2NI can be taken up highly by B16F10 melanoma tumors and then achieve the good green and red fluorescent imaging in B16F10 melanoma tumors. Therefore APTSPP-2NI can be considered as a potential tumor-targeting dual-mode enhanced probe in fluorescent imaging in vitro and in vivo.

Titanium dioxide (TiO2) nanowires (NWs) are usually considered to be brittle semiconductor materials, which limits their use in strain-related applications, even though they are already widely appl...

Transition-metal-doping can improve some physical properties of titanium dioxide (TiO2) nanowires (NWs), which leads to important applications in miniature devices. Here, we investigated the elastic moduli of single-crystalline pristine and Fe-doped rutile TiO2 NWs using the three-point bending method, which is taken as a case study of impacts on the elastic properties of TiO2 NWs caused by transition-metal-doping. The Young's modulus of the pristine rutile TiO2 NWs decreases when the cross-sectional area increases (changing from 246 GPa to 93.2 GPa). However, the elastic modulus of the Fe-doped rutile NWs was found to increase with the cross-sectional area (changing from 91.8 GPa to 200 GPa). For NWs with similar geometrical size, the elastic modulus (156.8 GPa) for Fe-doped rutile NWs is 24% smaller than that (194.5 GPa) of the pristine rutile TiO2 NWs. The vacancies generated by Fe-doping are supposed to cause the reduction of elastic modulus of rutile TiO2 NWs. This work provides a fundamental understanding of the effects of transition-metal-doping on the elastic properties of TiO2 NWs.

Carbon nanothread (C-NTH) is a new ultrathin one-dimensional sp3 carbon nanostructure, which exhibits promising applications in novel carbon nanofibers and nanocomposites. Recently, researchers have successfully developed a new alternative structure - ultrathin carbon nitride nanothread (CN-NTH). In this work, we investigate the mechanical properties of CN-NTHs through large-scale molecular dynamics simulations. Comparing with their C-NTH counterparts, CN-NTHs are found to exhibit a higher tensile and bending stiffness. In particular, because of the bond redistribution, the CN-NTHs in the polymer I group and tube (3,0) group are found to possess a higher failure strain than their C-NTH counterparts. However, the CN-NTH in the polytwistane group has a smaller failure strain compared with the pristine C-NTH. According to the atomic configurations, the presence of nitrogen atoms always leads to stress/strain concentrations for the nanothreads under tensile deformation. This study provides a comprehensive understanding of the mechanical properties of CN-NTHs, which should shed light on their potential applications such as fibers or reinforcements for nanocomposites.

3D Printed biodegradable polymeric scaffolds are critical to repair a bone defect, which can provide the individual porous and network microenvironments for cell attachment and bone tissue regeneration. Biodegradable PCL/HA composites were prepared with the blending of poly(ε-caprolactone) (PCL) and hydroxyapatite nanoparticles (HA). Subsequently, the PCL/HA scaffolds were produced by the melting deposition-forming method using PCL/HA composites as the raw materials in this work. Through a serial of in vitro assessments, it was found that the PCL/HA composites possessed good biodegradability, low cell cytotoxicity, and good biocompatibility, which can improve the cell proliferation of osteoblast cells MC3T3-E1. Meanwhile, in vivo experiments were carried out for the rats with skull defects and rabbits with bone defects. It was observed that the PCL/HA scaffolds allowed the adhesion and penetration of bone cells, which enabled the growth of bone cells and bone tissue regeneration. With a composite design to load an anticancer drug (doxorubicin, DOX) and achieve sustained drug release performance, the multifunctional 3D printed PCL/HA/DOX scaffolds can enhance bone repair and be expected to inhibit probably the tumor cells after malignant bone tumor resection. Therefore, this work signifies that PCL/HA composites can be used as the potential biodegradable scaffolds for bone repairing.

Janus two-dimensional materials with large Rashba spin splitting and high electron mobility are rarely reported but highly desired for nanoscale spintronics. Herein, using density functional theory calculations, we predicated Janus Sb2SexTe3–x (x = 1 or 2) monolayers simultaneously harboring these fascinating properties. The predicated monolayers are indirect semiconductors with great dynamical, thermal, and mechanical stability. The spin–orbital coupling (SOC) and the out-of-plane asymmetry lead to Rashba spin splitting at the conduction band minimum (CBM), which can be effectively tuned by the small uniaxial strain. The strong band dispersion at the CBM leads to small electron effective mass, consequently enabling a high electron mobility that reaches up to 6816.63 cm2 V–1 s–1. Moreover, Janus Sb2SexTe3–x monolayers possess great light absorption capability within the visible and infrared regions of solar light. Our findings highlight promising candidates for high-speed spintronic devices and may motivate more research efforts on carrier transport and SOC effects in Janus group V and VI monolayers.

High-risk arsenic contamination found in aqueous system is reported across the world and causing severe environmental issues. In this study, the Mg-Al Layered Double Hydroxide (LDH) modified by sulphur species (LDH-S) was found exhibiting high effectivity and selectivity in As(V) removal owing to the strong interaction between embedded HS- and AsO43-. The LDH-S with Mg to Al ratio 2–1 give the best performance with As(V) adsorption capacity 40.8 mg/g, which is 715% higher than that of pristine LDH (2–1). The adsorbent exhibits a high tolerance to concentrated competitive anions. In the continuous flow test, the adsorbent can reduce the As(V) concentration from 20 ppm to below-ppb-level indicating the potential in industry application. The adsorption mechanism is experimentally investigated and examined by Density Function Theory (DFT) calculation. The result illustrates that, differ from the traditional ion exchange mechanism of LDH, the enhanced removal capacity and selectivity of LDH-S for As(V) is attributed to the strong affinity between H atom from HS- ion (in the interlayer region of LDH) and the O atom from AsO43-.

© 2019 Elsevier B.V. Inhaled nanoparticles (NPs) are experienced by the first biological barrier inside the alveolus known as lung surfactant (LS), a surface tension reducing agent, consisting of phospholipids and proteins in the form of the monolayer at the air-water interface. The monolayer surface tension is continuously regulated by the alveolus compression and expansion and protects the alveoli from collapsing. Inhaled NPs can reach deep into the lungs and interfere with the biophysical properties of the lung components. The interaction mechanisms of bare gold nanoparticles (AuNPs) with the LS monolayer and the consequences of the interactions on lung function are not well understood. Coarse-grained molecular dynamics simulations were carried out to elucidate the interactions of AuNPs with simplified LS monolayers at the nanoscale. It was observed that the interactions of AuNPs and LS components deform the monolayer structure, change the biophysical properties of LS and create pores in the monolayer, which all interfere with the normal lungs function. The results also indicate that AuNP concentrations >0.1 mol% (of AuNPs/lipids) hinder the lowering of the LS surface tension, a prerequisite of the normal breathing process. Overall, these findings could help to identify the possible consequences of airborne NPs inhalation and their contribution to the potential development of various lung diseases.

Nanomaterials are currently the state-of-the-art in the development of advanced biomedical devices and applications where classical approaches have failed. To date, majority of the literature on nanomaterial interaction with cells have largely focused on the biological responses of cells obtained via assays, with little interest on their biophysical responses. However, recent studies have shown that the biophysical responses of cells, such as stiffness and adhesive properties, play a significant role in their physiological function. In this paper, we investigate cell biophysical responses after uptake of nanoparticles. Atomic force microscopy was used to study changes in cell stiffness and adhesion upon boron nitride (BN) and hydroxyapatite (HAP) nanoparticle uptake. Results show increase in cell stiffness with varying nanoparticle (BN and HAP) concentration, while a decrease in cell adhesion trigger by uptake of HAP. In addition, changes in the biochemical response of the cell membrane were observed via Raman spectroscopy of nanoparticle treated cells. These findings have significant implications in biomedical applications of nanoparticles, e.g. in drug delivery, advanced prosthesis and surgical implants.

Nanotechnology has quickly emerged as a promising research field with potential effects in disease treatments. For example, gold nanoparticles (AuNPs) have been extensively used in diagnostics and therapeutics. When administrated into human tissues, AuNPs first encounter extracellular matrix (ECM) molecules. Amongst all the ECM components, collagen is the main tension-resisting constituent, whose biofunctional and mechanical properties are strongly dependent on its hierarchical structure. Therefore, an in-depth understanding of the structural response of collagen to the presence of gold nanosurfaces (AuNS) and AuNPs is crucial in terms of clinical applications of AuNPs. However, detailed understanding of the molecular-level and atomic-level interaction between AuNS/AuNPs and collagen in the ECM is elusive. In this study, comprehensive molecular dynamics (MD) simulations have been performed to investigate the molecular behaviour of a collagen molecule segment (CMS) in the presence of AuNS/AuNPs in explicit water, aiming to explore the interaction of AuNS/AuNPs with collagen triple helices at the molecular and atomic levels. The results show that the CMS forms a rapid association with AuNS/AuNPs and undergoes a severe unfolding upon adsorption on AuNS/AuNPs, indicating an unfolding propensity of gold surfaces. We conclude that collagen triple helices unfold readily on AuNS and bare AuNPs, due to the interaction of gold surfaces with the protein backbone. The revealed clear unfolding nature and the unravelled atomic-level unfolding mechanism of collagen triple helices onto AuNPs contribute to the development of AuNPs for biomedical and therapeutic applications, and the design of gold-binding proteins.

The "titanium fire" as produced during high pressure and friction is the major failure scenario for aero-engines. To alleviate this issue, Ti-V-Cr and Ti-Cu-Al series burn resistant titanium alloys have been developed. However, which burn resistant alloy exhibit better property with reasonable cost needs to be evaluated. This work unveils the burning mechanisms of these alloys and discusses whether burn resistance of Cr and V can be replaced by Cu, on which thorough exploration is lacking. Two representative burn resistant alloys are considered, including Ti14(Ti-13Cu-1Al-0.2Si) and Ti40(Ti-25V-15Cr-0.2Si)alloys. Compared with the commercial non-burn resistant titanium alloy, i.e., TC4(Ti-6Al-4V)alloy, it has been found that both Ti14 and Ti40 alloys form "protective" shields during the burning process. Specifically, for Ti14 alloy, a clear Cu-rich layer is formed at the interface between burning product zone and heat affected zone, which consumes oxygen by producing Cu-O compounds and impedes the reaction with Ti-matrix. This work has established a fundamental understanding of burning resistant mechanisms for titanium alloys. Importantly, it is found that Cu could endow titanium alloys with similar burn resistant capability as that of V or Cr, which opens a cost-effective avenue to design burn resistant titanium alloys., 6 figures

The contribution of the proteoglycan to the strain-rate-dependent mechanical behaviour of cartilage tissues has been suggested to decrease with an increase in the strain-rate. On the other hand, the contribution from the collagen network has been suggested to increase as the strain-rate increases. These conclusions are drawn mainly based on numerical studies conducted on high-load-bearing knee cartilage tissues, while experimental evidence of these behaviours have not been demonstrated previously. Further, in contrast to the reported findings on high-load bearing knee cartilage, our previous study on the low-load-bearing kangaroo shoulder cartilage indicated that proteoglycan and collagen contribution remained steady as the strain-rate increases. Therefore, in the present study, we experimentally investigate the contribution of proteoglycan and collagen network to the strain-rate-dependent behaviour of the kangaroo knee cartilage, and plausible reasons for the differences observed in relation to the kangaroo shoulder cartilage. Firstly, in order to quantify the contribution of proteoglycans and collagen network, the indentation testings on normal, proteoglycan, and collagen-degraded kangaroo knee cartilage were conducted at different strain-rates. Then, structural and compositional differences between the kangaroo knee and shoulder cartilage were assessed qualitatively through polarised light microscopy (PLM) imaging and histological staining. Identified differences in the collagen architecture and proteoglycan composition were incorporated in a fibril-reinforced porohyperelastic Finite Element (FE) model with the objective of explaining the mechanisms underlying differences observed between the two tissues. Experimental results on knee cartilage indicated that when the strain-rate increases, proteoglycan contribution decreases while collagen contribution increases, where statistically significant differences were identified at each strain-rate (p 0.05). PLM images revealed a sizable deep zone in the kangaroo knee cartilage where collagen fibrils were oriented perpendicular to the subchondral bone. On the other hand, no such apparent deep zone was observed in the shoulder cartilage. FE model confirmed that the biomechanical differences observed in the knee and shoulder cartilage are due to the differences in the collagen fibril arrangement in the deep zone. From these results, it can be concluded that in high-load-bearing cartilage tissues, the collagen network in the deep zone assists in increasing the stiffness of tissue with strain-rate and plays a significant role in supporting transient loads. This, in turn, helps protect the solid matrix against large distortions and strains at the subchondral junction, pointing to the importance of the collagen network in deep zone in assisting high-load-bearing cartilage tissues.

Red blood cells (RBCs) are the main component of the blood and comprise about 45% of the total volume of blood. The key role of RBCs is to transfer oxygen from pulmonary capillaries to tissue capillaries, and transfer carbon dioxide from tissues to lungs. While some of these capillaries have uniform cross-sections, some non-uniform capillaries are also present. Often the diameters of these cross sections are smaller than the diameter of the RBCs. Yet because of the high deformability of its viscoelastic membrane, the RBCs are able to flow through these capillaries. The purpose of this analysis is therefore to investigate the flow activity of RBCs during their passage through a non-uniform capillary using the Lattice Boltzmann – Immersed Boundary (LB-IB) method.

As a typical class of single‐atom catalysts (SACs) possessing prominent advantages of high reactivity, high selectivity, high stability, and maximized atomic utilization, emerging metal‐nitrogen‐doped carbon (M‐N‐C) materials, wherein dispersive metal atoms are coordinated to nitrogen atoms doped in carbon nanomaterials, have presented a high promise to replace the conventional metal or metal oxides‐based catalysts. In this work, recent progress in M‐N‐C‐based materials achieved in both theoretical and experimental investigations is summarized and general principles for novel catalysts design from electronic structure modulating are provided. Firstly, the applications and mechanisms on the advantages and challenges of M‐N‐C‐based materials for a variety of sustainable fuel generation and bioinspired reactions, including the oxygen reduction reaction (ORR), oxygen evolution reaction (OER), hydrogen evolution reaction (HER), carbon dioxide reduction reaction (CO2RR), nitrogen reduction reaction (NRR), and nanozyme reactions are reviewed. Then, strategies toward enhancing the catalytic performance by engineering the nature of metal ion centers, coordinative environment of active centers, carbon support, and their synergistic cooperation, are proposed. Finally, prospects for the rational design of next generation high‐performance M‐N‐C‐based catalysts are outlined. It is expected that this work will provide insights into high‐performance catalysts innovation for sustainable and environmental technologies.

Storage lesion is a critical issue facing transfusion treatments, and it adversely affects the quality and viability of stored red blood cells (RBCs). RBC deformability is a key indicator of cell health. Deformability measurements of each RBC unit are a key challenge in transfusion medicine research and clinical haematology. In this paper, a numerical study, inspired from the previous research for RBC deformability and morphology predictions, is conducted for the first time, to investigate the deformability and morphology characteristics of RBCs undergoing storage lesion. This study investigates the evolution of the cell shape factor, elongation index and membrane spicule details, where applicable, of discocyte, echinocyte I, echinocyte II, echinocyte III and sphero-echinocyte morphologies during 42 days of in-vitro storage at 4 &deg, C in saline-adenine-glucose-mannitol (SAGM). Computer simulations were performed to investigate the influence of storage lesion-induced membrane structural defects on cell deformability and its recoverability during optical tweezers stretching deformations. The predicted morphology and deformability indicate decreasing quality and viability of stored RBCs undergoing storage lesion. The loss of membrane structural integrity due to the storage lesion further degrades the cell deformability and recoverability during mechanical deformations. This numerical approach provides a potential framework to study the RBC deformation characteristics under varying pathophysiological conditions for better diagnostics and treatments.

Collagen undergoes many types of post-translational modifications (PTMs), including intracellular modifications and extracellular modifications. Among these PTMs, glycosylation of hydroxylysine (Hyl) is the most complicated. Experimental studies demonstrated that this PTM ceases once the collagen triple helix is formed and that Hyl-O-glycosylation modulates collagen fibrillogenesis. However, the underlying atomic-level mechanisms of these phenomena remain unclear. In this study, we first adapted the force field parameters for O-linkages between Hyl and carbohydrates and then investigated the influence of Hyl-O-glycosylation on the structure of type I collagen molecule, by performing comprehensive molecular dynamic simulations in explicit solvent of collagen molecule segment with and without the glycosylation of Hyl. Data analysis demonstrated that (i) collagen triple helices remain in a triple-helical structure upon glycosylation of Hyl; (ii) glycosylation of Hyl modulates the peptide backbone conformation and their solvation environment in the vicinity and (iii) the attached sugars are arranged such that their hydrophilic faces are well exposed to the solvent, while their hydrophobic faces point towards the hydrophobic portions of collagen. The adapted force field parameters for O-linkages between Hyl and carbohydrates will aid future computational studies on proteins with Hyl-O-glycosylation. In addition, this work, for the first time, presents the detailed effect of Hyl-O-glycosylation on the structure of human type I collagen at the atomic level, which may provide insights into the design and manufacture of collagenous biomaterials and the development of biomedical therapies for collagen-related diseases.

Homochirality is very important in the formation of advanced biological structures, but the origin and evolution mechanisms of homochiral biological structures in complex hierarchical process is not clear at the single-molecule level. Here we demonstrate the single-molecule investigation of biological homochirality in the hierarchical peptide assembly, regarding symmetry break, chirality amplification, and chirality transmission. We find that homochirality can be triggered by the chirality unbalance of two adsorption configuration monomers. Co-assembly between these two adsorption configuration monomers is very critical for the formation of homochiral assemblies. The site-specific recognition is responsible for the subsequent homochirality amplification and transmission in their hierarchical assembly. These single-molecule insights open up inspired thoughts for understanding biological homochirality and have general implications for designing and fabricating artificial biomimetic hierarchical chiral materials., Most chiral molecules and structures in living organisms exist as single enantiomers, but why? Here, the authors investigated surface-mediated homochirality on the single-molecule level and show that it can be triggered by the chirality unbalance of two adsorption configuration monomers.

Metal–organic frameworks (MOFs) combining the merits of both organic and inorganic functional building structures are fundamentally important and can meet the requirement of vast scientific and technological applications. Intrigued from the fact that transition metals (TMs) are widely embedded in the carbon sp2 network or strongly interact with a bare graphene edge, the single transition metal atom may work as a linker to connect carbon chains to build nanoarchitectures. A new MOF building structure, [Metal–Carbon–(Benzene)i–Chain]n ring abbreviated as [M-CBiC]n (M = Ti, V, and Cr), with increasing carbon chain length i (= 0, 1, 2, ···), was proposed as carbon chains CBiC connected by a single transition metal atom M to form a ring structure with multiedges n (= 2–6), based on advanced computational methods. They are thermodynamically stable and chemically and physically versatile with ring shape, electronic structures, optical response, as well as hydrogen adsorption energy that vary by changing the leng...

From first-principles calculations based on density functional theory, we find that the recently synthesized β12 boron sheet is a perfect candidate for calcium-decoration and hydrogen storage application. In contrast to graphene where defects are required to capture Ca, the naturally formed hexagonal hollow ring in β12 boron sheet provides the ideal site for Ca adsorption, and up to 6H2 molecules for each Ca atom can be captured with a desirable binding energy of ∼0.2 eV/H2. The gravimetric hydrogen density for Ca decorated boron sheet can reach up to 8.92 wt%. From the electronic analysis, it is found that both the orbital hybridizations and polarization mechanism play significant roles in H2 adsorption and storage.

To facilitate the biomedical applications of biocomposites, researchers have used different types of fillers to enhance their mechanical properties. However, the addition of fillers not only changes the mechanical performance of the biocomposites, but also affects their printability, that is, their rheological properties. With the aid of atomistic simulations, this work investigates the influence of graphene size and aggregation on the rheological properties of polycaprolactone (PCL) composites. For the same weight ratio, increasing the graphene size causes the viscosity of the PCL composite to increase until a threshold edge length equal to PCL's average radius of gyration. After this threshold value, the viscosity decreases with increasing edge length. The PCL composite with multilayered graphene exhibits a lower viscosity compared with its counterpart with monolayer graphene. Specifically, the addition of graphene is shown to augment the shear-thinning effect. The findings in this work provide a fundamental understanding of the rheological property of PCL composites with the addition of 2D nanofillers, which shed light on the ink design for bioprinting.

Low-dimensional carbon nanostructures are ideal nanofillers to reinforce the mechanical performance of polymer nanocomposites due to their excellent mechanical properties. Through molecular dynamics simulations, the mechanical performance of poly(vinyl alchohol) (PVA) nanocomposites reinforced with a single-layer diamond – diamane is investigated. It is found the PVA/diamane exhibits similar interfacial strengths and pull-out characteristics with the PVA/bilayer-graphene counterpart. Specifically, when the nanofiller is fully embedded in the nanocomposite, it is unable to deform simultaneously with the PVA matrix due to the weak interfacial load transfer efficiency, thus the enhancement effect is not significant. In comparison, diamane can effectively promote the tensile properties of the nanocomposite when it has a laminated structure as it deforms simultaneously with the matrix. With this configuration, the interlayer sp3 bonds endows diamane with a much higher resistance under compression and shear tests, thus the nanocomposite can reach very high compressive and shear stress. Overall, enhancement on the mechanical interlocking at the interface as triggered by surface functionalization is only effective for the fully embedded nanofiller. This work provides a fundamental understanding of the mechanical properties of PVA nanocomposites reinforced by diamane, which can shed lights on the design and preparation of next generation high-performance nanocomposites.

"Titanium fire" can cause catastrophic consequences for machinery components made of titanium alloys, especially in the case of aero-engines. As such, there is continuing interests in developing burn resistant titanium alloys. The burn resistant functionality and mechanical strength of titanium alloys rely on their microstructural characteristics that are significantly determined by the alloying components. This work investigated the burn resistant performance of Ti-Cu alloy and analyzed the role of alloying Cu. With sufficient content of Cu in the system, the formation of Cu rich layer cuts off the oxygen transfer pathway and hinders the burning process. Meanwhile, the addition of Cu results in the reduction of chemical kinetics. For the Ti-Cu alloy with insufficient Cu content, the burn resistance is sacrificed by the discontinuous Cu-rich clusters, among which oxygen penetration prolongs the burning process. Apart from the Cu-rich protective layer, various burning processes accompanied with oxidation products are detected via reduced area X-ray diffraction along the burnt cross section. This work provides a comprehensive understanding of the impacts of Cu content on the burn resistant characteristics of Ti-Cu alloy, which offers theoretical foundation of burn resistant mechanism to the design and fabrication of high-performance titanium alloys.

Highlights - Advanced numerical model for micro-particle TD in the human lung is developed. - This study is conducted for 17-generation lung geometry for the first time. - The particle diameter effects are investigated for different breathing conditions. - This study will help pharmaceutical companies to design new drug delivery tools. Abstract The major problem in understanding the therapeutically targeted drug delivery system in the deeper airways of the human lung is the lack of adequate data of particle transport and deposition (TD) in the transitional and respiratory zones (deeper airways) of the human lung. An understanding of the morphometry of the pulmonary airways and the lungs forms the primary step in a study of pulmonary aerosol deposition. The present study is the first-ever approach to explore the pulmonary aerosol TD in a digital 17-generation human pulmonary airway model. The present numerical study achieved the lack of the particle TD data in the deeper airways of the human lung. This paper presents a 3-D (3-dimensioanl) CFD (Computational Fluid Dynamics) study of an anatomically realistic 17-generation lung bronchial tree model based on the high-resolution computer tomography (HRCT) data by Schmidt et al., (2004). Physical morphometry is necessary for sufficiently calculating air and particle dynamics in human pulmonary airways with available data on a large number of generations. A Lagrangian-based Discrete Phase Model (DPM) is used to study the particle TD in the 17-generation of the lung airways. The numerical results demonstrate that inertial impaction is dominant in the upper airways and a large percentage of particles is deposited in the upper airways. The numerical results also illustrate that a large percentage of smaller diameter particles leaves through the airway outlet boundary at the 17th generation irrespective of breathing patterns. The escaped particles are considered to continue to follow the airway flow field further downstream after the 17th generation till the 23rd generation and some of them will reach the alveolar sacs region. This computational model could potentially aid in overcoming the nanobiotechnology toxicity problem for drug delivery in the deeper airways.

Hydrogen purification from a mixture of gas is a critical step in hydrogen production as an energy source and other clean energy applications. Recently gas purification using membranes with sub-nanometer pores, such as porous graphene has offered an attractive option which purifies the targeted gas from other impurity gases based on size exclusion exploiting the differences in the gases' molecular size. Using a combination of density functional theory (DFT) and molecular dynamic (MD) simulations, we demonstrate that graphitic carbon nitride (g-C3N4), a graphene like 2-dimensional nanomaterial can effectively purify H2 from CO2 and CH4. However, under neutral conditions the H2 flux across the membrane is comparatively weak, and our theoretical analysis shows that the flux can be significantly improved by widening the pore area via applying biaxial strains as low as 2.5% and 5% on the membrane. Interestingly, the strain tuning only improves the membranes H2 permeability, while its excellent H2/CO2 and H2/CH4 selectivity is not compromised.

Carbon fibers, especially those constructed from carbon nanotubes (CNTs), have attracted intensive interests from both scientific and engineering communities due to their outstanding physical properties. In this workHere we report, we find that the recently synthesized recently synthesized ultrathin diamond nanothread (DNT) not only possesses excellent torsional deformation capability, but also has excellent interfacial load transfer efficiency. Comparing with the (10,10) carbon nanotube bundles, (1) By considering a seven strand fiber, the flattening of nanotubes as observed in (10,10) CNT bundles is not observed in DNTdiamond nanothread bundle, which . This endows the DNT bundle withleads to a high torsional elastic limit that is almost three times higherfour times as obtained from the (10,10) CNT bundle. Pull-out tests reveal that (2) Pull-out tests reveal that tthe DNT diamond nanothread bundle has has an interface transfer load of more than twice that of the CNT carbon naontube bundle, corresponding to an order of magnitude higher in terms of . (3) Tthe interfacial shear strength of the DNT bundle is an order of magnitude higher than that of the CNT bundle. Such high interface load transfer efficiency is attributed to the zigzag morphology of DNT, which introduces a strong mechanical interlocking effect at the interface through the stick-slip motion (totally different from the load transfer mechanism in CNT bundle). The aforementioned three aspects are commonly used to gauge the performance of fibers. Obviously,These intriguing features enable DNT diamond nanothread as exhibits excellent potential candidate for constructing next generation carbon fibers., Comment: 6 figures, published, Nature Communications, 2017

Currently, fluorescent imaging is one of the most promising diagnostic approaches for facile detection of cancers in situ in thanks to a fluorescent probe. Two novel polypeptide-based fluorescent probes for different biomarkers to cancers are reported here. These probes focused on tyrosine-isoleucine-glycine-serine-arginine (YIGSR) and arginine-glycine-aspartic (RGD), which receptors play an important role in the extracellular matrix and are overexpressed in tumor cells and then can be used as tumor-targeting groups in fluorescent imaging. In this work, the pentpeptide-rhodamine B derivative (YIGSR-RhB) and tripeptide-rhodamine B derivative (RGD-RhB) were synthesized respectively by using the solid phase synthesis methods. These derivatives were further characterized by 1HNMR, MS, UV and IR, etc. Their fluorescent and biocompatibility properties, such as the cell cytotoxicity, cell uptake and fluorescent imaging of tumor cells, and fluorescent imaging in BALB/c female mice with 4T1 tumors and C57 mice with B16F10 tumor in vivo, were also measured. Experiment results demonstrated that YIGSR-RhB and RGD-RhB possessed the low cell cytotoxicity, good tumor-targeting property and fluorescent properties similar to rhodamine B. Moreover, YIGSR-RhB and RGD-RhB can be taken up highly by the B16F10 melanoma cells and 4T1 breast cancer cells, and then achieve the good fluorescent imaging in these tumor cells in vitro and tumors of mice in vivo. Therefore, YIGSR-RhB and RGD-RhB can be used as the potential tumor-targeting probes for fluorescent imaging. They can directly attach the cell membrane and specifically target to the tumor cells.

The molecular behavior of proteins in the presence of inorganic surfaces is of fundamental biological significance. Examples include extracellular matrix proteins interacting with gold nanoparticles and metallic implant biomaterials, such as titanium and stainless steels. Uncharged inorganic surfaces that interact strongly with the solution phase (hydrophilic surfaces) have been commonly used in disease treatments. A deep understanding of the molecular behavior of body proteins in the presence of hydrophilic surfaces is important in terms of clinical applications. However, the adsorption mechanism of proteins onto hydrophilic surfaces remains not fully understood. Here, comprehensive molecular dynamics simulations are carried out to study the molecular response of a human collagen molecule segment (CMS) to the presence of a planar gold surface (AuNS) in explicit solvent, aiming to unravel the adsorption mechanism of proteins onto hydrophilic surfaces. The results demonstrate that in the presence of AuNS, the CMS first biasedly diffuses toward AuNS, followed by anchoring to the gold surface, and finally adsorbs stepwise onto AuNS, where the protein adjusts its structure to maximize the interaction with AuNS. We conclude that adsorption of proteins onto hydrophilic surfaces adheres to three steps, namely, biased diffusion, anchoring, and stepwise adsorption accompanied by structural adaptation. The obtained adsorption mechanism provides insights into the development of inorganic surfaces for biomedical and therapeutic applications.

Mineralization of bone is a dynamic process, involving a complex interplay between cells, secreted macromolecules, signaling pathways, and enzymatic reactions; the dysregulation of bone mineralization may lead to serious skeletal disorders, including hypophosphatemic rickets, osteoporosis, and rheumatoid arthritis. Very few studies have reported the role of osteocytes - the most abundant bone cells in the skeletal system and the major orchestrators of bone remodeling in bone mineralization, which is owed to their nature of being deeply embedded in the mineralized bone matrix. The Wnt/β-catenin signaling pathway is actively involved in various life processes including osteogenesis; however, the role of Wnt/β-catenin signaling in the terminal mineralization of bone, especially in the regulation of osteocytes, is largely unknown. This research demonstrates that during the terminal mineralization process, the Wnt/β-catenin pathway is downregulated, and when Wnt/β-catenin signaling is activated in osteocytes, dendrite development is suppressed and the expression of dentin matrix protein 1 (DMP1) is inhibited. Aberrant activation of Wnt/β-catenin signaling in osteocytes leads to the spontaneous deposition of extra-large mineralized nodules on the surface of collagen fibrils. The altered mineral crystal structure and decreased bonding force between minerals and the organic matrix indicate the inferior integration of minerals and collagen. In conclusion, Wnt/β-catenin signaling plays a critical role in the terminal differentiation of osteocytes and as such, targeting Wnt/β-catenin signaling in osteocytes may serve as a potential therapeutic approach for the management of bone-related diseases.

Two-dimensional (2D) magnetic materials are essential to developing high-performance spintronic devices. Recent experimental discoveries of several atomic thin 2D ferromagnetic materials have stimulated great interest in further exploring this fascinating class of materials. Here, combining an advanced crystal structure search method and extensive first-principles energetic and dynamic calculations, we have identified a planar ${\mathrm{CoB}}_{6}$ monolayer as a stable 2D ferromagnet. We show that the ferromagnetic ground state of the ${\mathrm{CoB}}_{6}$ monolayer remains robust in the ambient environment, and the magnetic stability and moment can be remarkably enhanced and tuned by external strain. Moreover, we propose feasible synthesis routes for the the newly predicted ${\mathrm{CoB}}_{6}$ monolayer, either by Co atom adsorption on the recently proposed ${\ensuremath{\delta}}_{4}$ boron sheet or by direct chemical growth. The present results establish a fundamental material and physics basis for synthesis and characterization of the ${\mathrm{CoB}}_{6}$ monolayer among the emerging 2D ferromagnetic materials.

Two dimensional boron nanosheets have been proposed theoretically for a decade, but were not experimentally synthesized until very recently. Research into their fundamental properties and device applications has since seen exponential growth. In this perspective, we review recent research progress related to 2D boron sheets, touching upon the topics of fabrication, properties, and applications, as well as discussing challenges and future research directions. We highlight the intrinsic electronic and mechanical properties of boron sheets, resulting from their diverse structures. Their facile fabrication and novel properties have inspired the design and demonstration of new nanodevices; however, further progress relies on resolving technical obstructions, like non-scalable fabrication techniques. We also briefly describe some feasible schemes that can address the associated challenges. It is expected that this fascinating material will offer tremendous opportunities for research and development in the foreseeable future.

By first-principle calculations, we have systematically studied the effect of strain/pressure on the electronic structure of rutile lead/stannic dioxide (PbO2/SnO2). We find that pressure/strain has a significant impact on the electronic structure of PbO2/SnO2. Not only can the band gap be substantially tuned by pressure/strain, but also a transition between a semiconductor and a gapless/band-inverted semimetal can be manipulated. Furthermore, the semimetallic state is robust under strain, indicating a bright perspective for electronics applications. In addition, a practical approach to realizing strain in SnO2 is then proposed by substituting tin (Sn) with lead (Pb), which also can trigger the transition from a large-band-gap to a moderate-gap semiconductor with enhanced electron mobility. This work is expected to provide guidance for full utilization of the flexible electronic properties in PbO2 and SnO2.

This work explores the application of a new one-dimensional carbon nanomaterial, the diamond nanothread (DNT), as a reinforcement for nanocomposites. Owing to the existence of Stone-Wales transformation defects, the DNT intrinsically possesses irregular surfaces, which is expected to enhance the non-covalent interfacial load transfer. Through a series of in silico pull-out studies of the DNT in polyethylene (PE) matrix, we found that the load transfer between DNT and PE matrix is dominated by the non-covalent interactions, in particular the van der Waals interactions. Although the hydrogenated surface of the DNT reduces the strength of the van der Waals interactions at the interface, the irregular surface of the DNT can compensate for the weak bonds. These factors lead to an interfacial shear strength of the DNT/PE interface comparable with that of the carbon nanotube (CNT)/PE interface. Our results show that the DNT/PE interfacial shear strength remains high even as the number of Stone-Wales transformation defects decreases. It can be enhanced further by increasing the PE density or introduction of functional groups to the DNT, both of which greatly increase the non-covalent interactions., in press, early view online in Advanced Functional Materials, 2016

It has been demonstrated that most cells of the body respond to osmotic pressure in a systematic manner. The disruption of the collagen network in the early stages of osteoarthritis causes an increase in water content of cartilage which leads to a reduction of pericellular osmolality in chondrocytes distributed within the extracellular environment. It is therefore arguable that an insight into the mechanical properties of chondrocytes under varying osmotic pressure would provide a better understanding of chondrocyte mechanotransduction and potentially contribute to knowledge on cartilage degeneration. In this present study, the chondrocyte cells were exposed to solutions with different osmolality. Changes in their dimensions and mechanical properties were measured over time. Atomic force microscopy (AFM) was used to apply load at various strain-rates and the force-time curves were logged. The thin-layer elastic model was used to extract the elastic stiffness of chondrocytes at different strain-rates and at different solution osmolality. In addition, the porohyperelastic (PHE) model was used to investigate the strain-rate-dependent responses under the loading and osmotic pressure conditions. The results revealed that the hypo-osmotic external environment increased chondrocyte dimensions and reduced Young's modulus of the cells at all strain-rates tested. In contrast, the hyper-osmotic external environment reduced dimensions and increased Young's modulus. Moreover, using the PHE model coupled with inverse FEA simulation, we established that the hydraulic permeability of chondrocytes increased with decreasing extracellular osmolality which is consistent with previous work in the literature. This could be due to a higher intracellular fluid volume fraction with lower osmolality.

Recent years have witnessed a large volume of works on the modification of graphene; however, an understanding of the associated morphology or mechanical properties changes is still lacking, which is vital for its engineering implementation. By taking the C4F fluorination as an example, we find that the morphology of both graphene sheet (GS) and graphene nanoribbon (GNR) can be effectively tailored by fluorination patterning via molecular dynamics simulations. The fluorine atom produces out-of-plane forces which trigger several intriguing morphology changes to monolayer graphene, including zigzag, folded, ruffle, nanoscroll, and chain structures. Notably, for multilayer GNR, the delamination and climbing phenomena of the surface layer are observed. Further studies show that the fluorination pattern can also be utilized to modulate the mechanical properties of graphene, e.g., about 40% increase of the effective yield strain is observed for the examined GNR with fluorination patterns. This study not only de...

The knowledge of respiratory particle transport in the extra-thoracic pathways is essential for the estimation of lung health-risk and optimization of targeted drug delivery. The published literature reports that a significant fraction of the inhaled aerosol particles are deposited in the upper airways, and available inhalers can deliver only a small amount of drug particles to the deeper airways. To improve the targeted drug delivery efficiency to the lungs, it is important to reduce the drug particle deposition in the upper airways. This study aims to minimize the unwanted aerosol particle deposition in the upper airways by employing a gas mixture model for the aerosol particle transport within the upper airways. A helium&ndash, oxygen (heliox) mixture (80% helium and 20% oxygen) model is developed for the airflow and particle transport as the heliox mixture is less dense than air. The mouth&ndash, throat and upper airway geometry are extracted from CT-scan images. Finite volume based ANSYS Fluent (19.2) solver is used to simulate the airflow and particle transport in the upper airways. Tecplot software and MATLAB code are employed for the airflow and particle post-processing. The simulation results show that turbulence intensity for heliox breathing is lower than in the case of air-breathing. The less turbulent heliox breathing eventually reduces the deposition efficiency (DE) at the upper airways than the air-breathing. The present study, along with additional patient-specific investigation, could improve the understanding of particle transport in upper airways, which may also increase the efficiency of aerosol drug delivery.

Hydrotalcite materials are generally utilized for anionic pollutants due to its interlayered anion exchange ability. Their potentiality for cationic contaminants is rarely explored. In this study, disulfide ( ) intercalated LDH material demonstrated capability to remove both heavy metal cations and oxyanions simultaneously from water. The intercalation of LDH significantly improved its adsorption capability towards both heavy metal cations ( and ) and oxyanion ( ). The adsorption amount of S-LDH towards and reached 88.6mg/g and 76.2mg/g, which are 405% and 281% higher than that of pristine LDH. For removal, the adsorption amount reached 34.7mg/g, 402% higher than that of pristine LDH. The cations capture mechanism mainly depends on the novel layer sheet cation substitution mechanism based on irreversible precipitation and the generation of metal sulfide precipitates. Meanwhile, the interlayered can be easily replaced by to realize the simultaneous removal of both heavy metal cations and oxyanions. In the fixed-bed column experiments, 448 bed volume (BV) (672 mL) of simulating electroplating wastewater can be efficiently treated by yielding only 1 BV(15 mL) of chemical sludge, which is practically acceptable. This work provided a highly practical adsorption technology based on the modification hydrotalcite material for the purification of heavy metal ions contaminated wastewater. Keywords: hydrotalcite heavy metal contaminants cation removal anion removal wastewater treatment