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In spite of the global advancements in science and technology, the disparity in the quality of life across the globe continues to increase, particularly so in terms of the access to cutting-edge medical technologies. Opportune transfer of technologies across the rich-poor divide lessens the global economic inequalities and fosters the sustainability of the global economy, but not all technologies are equally transferrable across this gap. Here, a method for quantifying the transferability of technologies has been postulated and preliminarily tested by considering twelve state-of-the-art medical technologies and three comparatively impoverished regions of the world: West Bengal in India, Xinjiang in China, and the former Yugoslav state of Montenegro. The results of the analysis demonstrate that neither the gross economic productivity of the region of interest nor its level of poverty can be the sole determinants of the transferability of technologies. Rather, a complex network of scientific, technological, infrastructural, socioeconomic, and cultural factors defines the extent of transferability of new technologies across the rich-poor divide. The proposed model helps to discern which of these factors represent the most critical hindrances in the transfer of technologies. It is argued that the most dependable technologies to transfer are old and proven ones, but the best ones for ameliorating the rich-poor divide are juvenile technologies in formative stages of their development, which also happen to be employing simplistic ingenuity and resourcefulness in their design. The analysis performed here makes it apparent that models for assessing the social value of technologies should inextricably tie the scientific factors with the socioeconomic and humanistic. Countless technical models of various natures could be devised with this holistic principle in mind. [ABSTRACT FROM AUTHOR]

Ferrites count among the most functionally versatile magnetic materials in use in high technologies. In this study, synthesis, characterization and assessment of potential for use in water remediation of two different types of nanostructured ferrites were performed. Barium hexaferrite (BaFe12O19, BHF) and strontium hexaferrite (SrFe12O19, SHF) nanoparticle preparation using a flash-combustion method was successful. The prepared samples were thoroughly characterized for their microstructure, morphology, elemental composition, functional groups, surface charge density and magnetic, dielectric and optical properties. The hexagonal phase was detected as the primary one in X-ray diffraction patterns, while vibrational spectrophotometry analyses demonstrated the presence of an M-type hexagonal structure. Temperature-dependent ferromagnetic behavior of the nanoparticles was indicated from the χ-T curves, with a slightly higher single transition temperature, Tc, for BHF than for SFH: 675 °C vs. 650 °C. Despite having nanocrystalline structures, both BHF and SHF were identified as hard magnetic materials, with saturation magnetizations of 56.7 and 54.3 emu/g, respectively, and anisotropy fields greater than 9 kOe. Finally, batch adsorption studies were used to remove Pb(II) ions from aqueous solutions at various pHs and contact times using the as-prepared materials as fresh sorbents. The highest adsorption capacity was achieved at pH 7 and after 60 min of the contact time, equivalent to 84% and 80% for BHF and SHF, respectively. Extrinsic microstructural factors, such as particle morphology, surface area and porosity, proved to be more important for promoting the sequestration of Pb(II) than the intrinsic, crystallographic factors. Consequently, BHF performed better as an adsorbent than SHF under all of the tested conditions. The investigated nanostructured hexaferrites also demonstrated an exceptional recycling capacity. [ABSTRACT FROM AUTHOR]

Scientific papers written as dialogues evoke Platonist philosophical discourses and are foreseen as elementary forms of expression in neoclassical scientific renaissance. Here we report on a study of the Brazil nut effect in a series of macroscopic and microscopic systems in the form of a play in three acts. The nut effect predicting the segregation of smaller grains at the bottom of the mixture and larger ones at the top was observed in a polydisperse mix of manually shaken playground pebbles, albeit following different kinetics than in an agitated pile of chess pieces. Common sense predicts that vertical, gravity-driven segregation in colloidal dispersions with heterogeneous particle size distributions is such that larger particles would settle toward the bottom and the lighter ones cream at the top. Here we refute this expectation and demonstrate that segregation of colloidal particles in the vertical direction conforms to the Brazil nut effect when the agitation is delivered in the forms of vortex mixing or audio vibration, but not when the colloids are manually shaken. The effect is demonstrated on aqueous dispersions of hydroxyapatite and iron oxide nanoparticles. Kinetic experiments showed that segregation increases with the agitation time in mixtures of pebbles and with the post-agitation aging time in fine particle colloids. The particle size gradient established due to agitation-induced segregation led to a corresponding gradient in optoelectronic properties—band gap, conductivity, lattice acoustics—in the vertical direction of the colloidal column for both types of nanoparticles. Such morphological gradients induced by the Brazil nut effect can be harnessed as affordable and facile templates for the synthesis of functionally gradient materials. Discussion of the mechanism and the application potential of the observed effect in colloidal and coarse systems is enriched with a literature review of this curious effect and entwined with the literary elements of the dramaturgical narrative involving a family of scientist in exile from mainstream scientific institutions: the mother, the father, an elementary school boy and a kindergarten girl. The narrative conforms in its structure to the shape of a Brazil nut and presents the first research study whose findings are enacted through a dream. The play questions the humaneness and creative prospects of modern science and celebrates children's science projects performed with meager resources and a plentiful of imagination, showing that they could be gateways to important scientific discoveries. [ABSTRACT FROM AUTHOR]

Purpose: SN-38 is an antineoplastic drug with a three orders of magnitude higher activity than its prodrug, irinotecan, a common chemotherapeutic of choice in the treatment of colorectal cancer. A considerable number of genes are known to alter their expression under the influence of free SN-38, but no studies have looked at the gene expression effects of SN-38 delivered via poly(D-L-lactide-co-caprolactone) (PLCL) nanoparticles yet. Method: We evaluated changes to expression levels of genes encoding for ubiquitin D (UBD), fibroblast growth factor 3 (FGF3), histone (HIST), and regulator of cell cycle (RGCC) in SW-480 colon cancer cells in response to free SN-38 and two types of poloxamer-coated PLCL (PEO-PPO-PEO/PLCL) nanoparticles as carriers for SN-38, containing different conformations of the hydrophilic stealth corona: dense or collapsed. Results: Both the free drug and the two drug-loaded nanoformulations upregulated UBD and RGCC and downregulated FGF3 and HIST, which was consistent with the pharmacological activity of SN-38. Still, there was a clear difference in gene expression levels in SW-480 cells depending on whether they were challenged with free SN-38 or with nanoparticles loaded with SN-38. Most critically, the delivery of SN-38 with the nanoparticles prolonged its mode of action and, in the case of genes such as UBD, FGF3, and HIST, provided for a more intense effect on gene expression alteration than that achieved by the drug alone. Conclusions: Nanoparticles comprising the collapsed PEO-PPO-PEO corona produced a more intense effect on gene expression alteration than the nanoparticles with the dense PEO-PPO-PEO corona. [ABSTRACT FROM AUTHOR]

Dental caries and periodontal disease are responsible for the most frequent set of chronic diseases in humans, for which no perfectly regenerative solutions are available yet. As a result, materials combining an intrinsic antibacterial activity with tissue regeneration properties for minimally invasive dental therapies are in high demand. Here we report on the fabrication and characterization of a novel nanocomposite material for such dental applications. The material is composed of narrowly disperse Na2O–CaO–P2O5–SiO2 bioglass-ceramic nanoparticles, 30–70 nm in diameter, doped with antibacterial and osteogenic zinc and niobium ions, and hybridized with chitosan. These systems were characterized for their particle size, morphology, atomic and phase composition, and glass-ceramic/polymer interface with the use of transmission electron microscopy, energy-dispersive X-ray analysis, X-ray diffraction and Fourier transform infrared spectroscopy. After annealing at 680 °C, amorphous silica in the bioglass-ceramic coexisted with silicalite-1 and combeite, the average crystallite size of which was 20–40 nm. In spite of the significantly better incorporation of zinc than of niobium inside the glass-ceramic network, zinc did not affect the particle size and shape distribution, while niobium lowered the average particle size. Chitosan increased the hydration capacity of the bioglass-ceramic and it formed a continuous interface around the bioglass-ceramic nanoparticles, devoid of micropores. This intimacy of the interface was confirmed by the downshift of the critical Si–O(–Si) vibration modes in the bioglass-ceramic upon hybridization with chitosan. The addition of zinc ions hampered the partial recrystallization during annealing by interfering with the Si–O network restructuring, in direct proportion with its concentration. Niobium ions produced a similar structure-breaking effect, which was evidenced, as in the case of zinc, by upshifting the antisymmetric Si–O–Si stretch of the bridging oxygen and increasing the full-width at half maxima for all the major Si–O(–Si) vibration modes. The effective electrostatic attraction between the aminated hydrocarbon chains of chitosan and the negatively charged silanol groups of silica may extend to the interaction with dentin collagen fibrils decalcified due to caries, making the material of potential interest for adhesive fillers of cariogenic lesions in teeth. Both the undoped and the doped bioactive glass-ceramics interacted favorably with odontoblast-like cells, accentuating their potential for further research for applications in minimally invasive reparative dentistry. Highlights: Chitosan-coated Zn- or Nb-doped Na2O–CaO–P2O5–SiO2 bioglass ceramic was synthesized and characterized. Chitosan increased the hydration capacity and formed a continuous interface around the nanoparticles. Zn hampered the recovery during annealing and Nb promoted it. Both Zn and Nb exhibited structure-breaking effects on the Si–O–Si glassy network. Zn-doped material was less viable to odontoblasts than the control and the Nb-doped one at low dosages. [ABSTRACT FROM AUTHOR]

Substituting small molecule drugs with abundant and easily affordable ions may have positive effects on the way countless disease treatments are approached. The interest in strontium cation in bone therapies soared in the wake of the success of strontium ranelate in the treatment of osteoporosis. A new method for producing thin strontium-containing hydroxyapatite (Sr-HA, Ca9Sr(PO4)6(OH)2) films as coatings that render bioinert titanium implant bioactive is reported here. The method is based on the combination of a mechanochemical synthesis of Sr-HA targets and their deposition in form of thin films on top of titanium with the use of laser ablation at low pressure. The films were 1–2 μm in thickness and their formation was studied at different temperatures, including 25, 300, and 500 °C. Highly crystalline Sr-HA target transformed during pulsed laser deposition to a fully amorphous film, whose degree of long-range order recovered with temperature. Particle edges became somewhat sharper and surface roughness moderately increased with temperature, but the (Ca+Sr)/P atomic ratio, which increased 1.5 times during the film formation, remained approximately constant at different temperatures. Despite the mostly amorphous structure of the coatings, their affinity for capturing atmospheric carbon dioxide and accommodating it as carbonate ions that replace both phosphates and hydroxyls of HA was confirmed in an X-ray photoelectron spectroscopic analysis. As the film deposition temperature increased, the lattice voids got reduced in concentration and the structure gradually "closed," becoming more compact and entailing a linear increase in microhardness with temperature, by 0.03 GPa/°C for the entire 25–500 °C range. Biocompatibility and bioactivity of Sr-HA thin films deposited on titanium were confirmed in an interaction with dental pulp stem cells, suggesting that these coatings, regardless of the processing temperature, may be viable candidates for the surface components of metallic bone implants. [ABSTRACT FROM AUTHOR]

To test if the transit of a nanoparticle across different organs in the body affects its properties at the final destination, we devised an in vitro system that mimics the passage of nanoparticles from the blood to the lung to the brain and, occasionally, back to the blood. Each of the three media provided a unique corona to the nanoparticles, comprising mainly secreted, blood-specific proteins in the plasma and membrane proteins in the lung and the brain. The hard corona changed during the transit of the nanoparticle between different organs. Cellular uptake, antibacterial activity, and drug release kinetics were analyzed to assess the difference in the biological response to nanoparticles depending on the transit route. Drug release assays most consistently demonstrated the effects of the history of the nanoparticle passage across different media on its present properties. Both the uptake analysis and antibacterial assays showed that the key proteins for these two processes in the brain replace their analogues from the lung, but are ineffective in replacing the blood plasma content from the nanoparticle surface. Notwithstanding that some routes can erase the history of the passage of the nanoparticle across different organs, the route traversed by it mostly affects the properties it displays at the destination. A nanoparticle sent to a circular journey through an array of media can have different properties upon its return to the point of origin. History is an essential determinant of the properties of nanoparticles in biological milieus, the memory of which is inscribed in the nanoparticle corona. [ABSTRACT FROM AUTHOR]

Scientific articles have been traditionally written from single points of view. In contrast, new knowledge is derived strictly from a dialectical process, through interbreeding of partially disparate perspectives. Dialogues, therefore, present a more veritable form for representing the process behind knowledge creation. They are also less prone to dogmatically disseminate ideas than monologues, alongside raising awareness of the necessity for discussion and challenging of differing points of view, through which knowledge evolves. Here we celebrate 250 years since the discovery of the chemical identity of the inorganic component of bone in 1769 by Johan Gottlieb Gahn through one such imaginary dialogue between two seasoned researchers and aficionados of this material. We provide the statistics on ups and downs in the popularity of this material throughout the history and also discuss important achievements and challenges associated with it. The shadow of Samuel Beckett's Waiting for Godot is cast over the dialogue, acting as its frequent reference point and the guide. With this dialogue presented in the format of a play, we provide hope that conversational or dramaturgical compositions of scientific articles—albeit virtually prohibited from the scientific literature of the day—may become more pervasive in the future. [ABSTRACT FROM AUTHOR]

This review presents thoughts on some of the fundamental features of conceptual models applied in the design of fine particles in the frames of colloid and soft chemistry. A special emphasis is placed on the limitations of these models, an acknowledgment of which is vital in improving their intricacy and effectiveness in predicting the outcomes of the corresponding experimental settings. Thermodynamics of self-assembly phenomena illustrated on the examples of protein assembly and micellization is analyzed in relation to the previously elaborated thesis that each self-assembly in reality presents a co-assembly, since it implies a mutual reorganization of the assembling system and its immediate environment. Parameters used in the design of fine particles by precipitation are discussed while referring to solubility product, various measures of supersaturation levels, induction time, nucleation and crystal growth rates, interfacial energies, and the Ostwald-Lussac law of phases. Again, the main drawbacks and inadequacies of using the aforementioned parameters in tailoring the materials properties in a soft and colloidal chemical setting were particularly emphasized. The basic and practical limitations of zeta-potential analyses, routinely used to stabilize colloidal dispersions and initiate specific interactions between soft chemical entities, were also outlined. The final section of the paper reiterates the unavoidable presence of practical qualitative models in the design and control of nanoparticulate colloids, which is supported by the overwhelming complexity of quantitative relationships that govern the processes of their formation and assembly. [ABSTRACT FROM AUTHOR]

Indications exist that paramagnetic calcium phosphates may be able to promote regeneration of bone faster than their regular, diamagnetic counterparts. In this study, analyzed was the influence of paramagnetic cobalt-substituted hydroxyapatite nanoparticles on osteoporotic alveolar bone regeneration in rats. Simultaneously, biocompatibility of the material was tested in vitro, on osteoblastic MC3T3-E1 and epithelial Caco-2 cells in culture. The material was shown to be biocompatible and nontoxic when added to epithelial monolayers in vitro, while it caused a substantial decrease in the cell viability as well as deformation of the cytoskeleton and cell morphology when incubated with the osteoblastic cells. In the course of 6 months after the implantation of the material containing different amounts of cobalt, ranging from 5 to 12 wt%, in the osteoporotic alveolar bone of the lower jaw, the following parameters were investigated: histopathological parameters, alkaline phosphatase and alveolar bone density. The best result in terms of osteoporotic bone tissue regeneration was observed for hydroxyapatite nanoparticles with the largest content of cobalt ions. The histological analysis showed a high level of reparatory ability of the nanoparticulate material implanted in the bone defect, paralleled by a corresponding increase in the alveolar bone density. The combined effect of growth factors from autologous plasma admixed to cobalt-substituted hydroxyapatite was furthermore shown to have a crucial effect on the augmented osteoporotic bone regeneration upon the implantation of the biomaterial investigated in this study. [ABSTRACT FROM AUTHOR]

A simple and green chemical method has been developed to synthesize stable bare and capped silver nanoparticles based on the reduction of silver ions by glucose and capping by poly(α,γ, l-glutamic acid) (PGA). The use of ammonia during synthesis was avoided. PGA has had a dual role in the synthesis and was used as a capping agent to make the silver nanoparticle more biocompatible and to protect the nanoparticles from agglomerating in the liquid medium. The synthesized PGA-capped silver nanoparticles in the size range 5-45 nm were stable over long periods of time, without signs of precipitation. Morphological examination has shown that the silver nanoparticles had a nearly spherical, multiply twinned structure. The effects of the reaction temperature and the reaction time during the synthesis were investigated too. The biocompatibility of the PGA-capped silver nanoparticles is discussed in terms of in vitro toxicity with human intestinal Caco-2 cells. The samples were characterized by UV-Visible spectroscopy, field emission scanning electron microscopy, transmission electron microscopy, and zeta potential measurements. [ABSTRACT FROM AUTHOR]

In the past few hundred years, science has exerted an enormous influence on the way the world appears to human observers. Despite phenomenal accomplishments of science, science nowadays faces numerous challenges that threaten its continued success. As scientific inventions become embedded within human societies, the challenges are further multiplied. In this critical review, some of the critical challenges for the field of modern chemistry are discussed, including: (a) interlinking theoretical knowledge and experimental approaches; (b) implementing the principles of sustainability at the roots of the chemical design; (c) defining science from a philosophical perspective that acknowledges both pragmatic and realistic aspects thereof; (d) instigating interdisciplinary research; (e) learning to recognize and appreciate the aesthetic aspects of scientific knowledge and methodology, and promote truly inspiring education in chemistry. In the conclusion, I recapitulate that the evolution of human knowledge inherently depends upon our ability to adopt creative problem-solving attitudes, and that challenges will always be present within the scope of scientific interests. [ABSTRACT FROM AUTHOR]