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There is a great deal of interest in interactions between biomolecules and high frequency electromagnetic (EM) fields. To investigate these interactions, a variety of simulation methods are available. For small length and time scales (approximately $< $ $1 \,\mathrm{\mu }\mathrm{s}$ and $100 \,\mathrm{n}\mathrm{m}$), All-Atom Molecular Dynamics simulates every atom in the system. This captures the relevant physics to a high degree of accuracy. Phenomena such as electric field screening by counter-ions are emergent properties from the collective interactions of these atoms. For larger systems on longer time scales, however, this method is too computationally expensive. To reduce complexity, other simulation techniques such as Brownian Dynamics treat the solvent as a continuum, instead of explicitly. One typical assumption is that electric field interactions are electrostatic and subjected to Debye screening. Once charges start moving at high frequencies and velocities, however, charges are able to outrun the counter-ion cloud and this assumption breaks down. We propose a method of removing the electrostatic assumption without explicitly modeling the solvent or imposing a grid on the simulation. We demonstrate the charged wake can be modeled using a finite trail of charges. Interactions can be computed using electrostatic expressions only, but still capture electrodynamics.

Melanin is ubiquitous in living organisms across different biological kingdoms of life, making it an important, natural biomaterial. Its presence in nature from microorganisms to higher animals and plants is attributed to the many functions of melanin, including pigmentation, radical scavenging, radiation protection, and thermal regulation. Generally, melanin is classified into five types—eumelanin, pheomelanin, neuromelanin, allomelanin, and pyomelanin—based on the various chemical precursors used in their biosynthesis. Despite its long history of study, the exact chemical makeup of melanin remains unclear, and it moreover has an inherent diversity and complexity of chemical structure, likely including many functions and properties that remain to be identified. Synthetic mimics have begun to play a broader role in unraveling structure and function relationships of natural melanins. In the past decade, polydopamine, which has served as the conventional form of synthetic eumelanin, has dominated the literature on melanin-based materials, while the synthetic analogues of other melanins have received far less attention. In this perspective, we will discuss the synthesis of melanin materials with a special focus beyond polydopamine. We will emphasize efforts to elucidate biosynthetic pathways and structural characterization approaches that can be harnessed to interrogate specific structure–function relationships, including electron paramagnetic resonance (EPR) and solid-state nuclear magnetic resonance (ssNMR) spectroscopy. We believe that this timely Perspective will introduce this class of biopolymer to the broader chemistry community, where we hope to stimulate new opportunities in novel, melanin-based poly-functional synthetic materials.

The functions of secreted animal mucuses are remarkably diverse and include lubricants, wet adhesives, protective barriers, and mineralizing agents. Although present in all animals, many open questions related to the hierarchical architectures, material properties, and genetics of mucus remain. Here, we summarize what is known about secreted mucus structure, describe the work of research groups throughout the world who are investigating various animal mucuses, and relate how these studies are revealing new mucus properties and the relationships between mucus hierarchical structure and hydrogel function. Finally, we call for a more systematic approach to studying animal mucuses so that data sets can be compared, omics-style, to address unanswered questions in the emerging field of mucomics. One major result that we anticipate from these efforts is design rules for creating new materials that are inspired by the structures and functions of animal mucuses.

The clingfish attaches to rough surfaces with considerable strength using an intricate suction disc, which displays complex surface geometries from structures called papillae. However, the exact role of these structures in adhesion is poorly understood. To investigate the relationship between papillae geometry and adhesive performance, we developed an image processing tool that analyzed the surface and structural complexity of papillae, which we then used to model hydrodynamic adhesion. Our tool allowed for the automated analysis of thousands of papillae in specimens across a range of body sizes. The results led us to identify spatial trends in papillae across the complex geometry of the suction disc and to establish fundamental structure–function relationships used in hydrodynamic adhesion. We found that the surface area of papillae changed within a suction disc and with fish size, but that the aspect ratios and channel width between papillae did not. Using a mathematical model, we found that the surface structures can adhere considerably when subjected to disturbances of moderate to high velocities. We concluded that a predominant role of the papillae is to leverage hydrodynamic adhesion and wet friction to reinforce the seal of the suction disc. Overall, the trends in papillae characteristics provided insights into bioinspired designs of surface microstructures for future applications in which adhesion is necessary to attach to diverse surfaces (in terrestrial or aquatic environments), even when subjected to disturbance forces of randomized directionality.

Objective To compare the weight, height, BMI and nutritional status of patients with and without cleft lip and/or cleft palate (CLP).Design Cross-sectional studySetting Lagos University Teaching HospitalPatients, participants Patients with CLP and a control group of participants without CLP aged between 1 month and 6 years. All patients in the CLP group had not received surgical or nutritional intervention.Outcome measures Weight, height, BMI, their respective percentiles, and nutritional status according to the WHO 2006 growth curves of participantsResults Patients with CLP (n = 60, 21 males, 39 females, mean age: 19.1 months) had significantly lower percentile weight and height compared to those of controls (n = 60, 26 females, mean age, 23.6 months) in univariate analyses (all p < 0.01). Multivariate linear regression revealed significant interactions with age group for weight. In addition, proportions of underweight and short stature were significantly higher in the CLP group compared to the control group (all p < 0.05), and these significant differences were dependent on the age group with between-group significant differences only in age groups less than 25 months.Conclusions Overall, patients with CLP had significantly lower weight, height, BMI and nutritional status than their unaffected peers, and these differences were dependent on age group. Significantly lower nutritional status was seen in patients with CLP up to 24 months of age, which highlights the need for early nutritional intervention in the management of CLP.

Nanoparticles of elemental germanium have interesting optical and electronic properties and relatively low toxicity, making them attractive materials for biological and optoelectronic applications. The most common routes to colloidal Ge nanoparticles include metathesis reactions involving Zintl salts, hydride reduction of Ge halides, and thermal decomposition of organogermane precursors. Here we describe an alternative “heat-up” method for the synthesis of size- and shape-tunable Ge nanoparticles that are both crystalline and air stable. The readily available reagents GeI4, oleylamine, oleic acid, and hexamethyldisilazane are combined in one pot and heated to 260 °C, where a rapid nucleation event occurs and multifaceted nanoparticles of crystalline Ge form. By varying the concentration of GeI4, the nanoparticle size can be tuned from 6 to 22 nm with narrow size distributions. Adding trioctylphosphine yields cube-shaped particles, and switching the solvent to octadecene yields one-dimensional nanostructures. The Ge nanoparticles, which are fully air stable for more than 6 months, were characterized by XRD, TEM, HRTEM, EDS, XPS, DRIFT, and UV−visible spectroscopy.

A new modular, hybrid solar power system is designed to generate both electrical and thermal energy by utilizing the full solar spectrum. The key element, an infrared-transparent concentrator photovoltaic (CPV) module, acts as a spectrum splitter, dividing solar radiation into two parts. The ultraviolet and visible light (“in-band”) are converted to electricity with high efficiency in CPV cells, while the infrared light (“out-of-band”) is transmitted directly to a thermal receiver, where thermal power may be converted to electricity by a suitable heat engine or used directly for industrial process heat applications whenever needed. Here, we describe the optical design, modeling, fabrication, and performance validation of this novel spectrum splitting CPV module. A transfer matrix style approach, cumulative transmission model, is built to study the reflection, absorption, and transmission in each layer of the CPV module. To optimize the optical performance, different materials for module superstrate/substrate, encapsulant, cell substrate, and cooling fluids are compared in order to enhance the transmission of out-of-band light through the CPV module by minimizing absorption. Six antireflection coatings along with front and backside electrical contact grids are designed to maximize transmittance of in-band light to the cell and out-of-band light to the thermal receiver. The final design, currently being prototyped, predicts out-of-band light transmission to the thermal receiver of 74.1% (for the passively cooled version) and 65.3% (for the actively cooled version). When epitaxial liftoff technology is applied, the transmission will change to 80.8% (passively cooled) and 71.9% (actively cooled). Experimental prototypes show good agreement with modeled optical performance.

L’amiotrofia è un motivo raro di consultazione medica. Se ne rilevano quattro meccanismi principali: l’immobilizzazione, certe patologie sistemiche, i danni del sistema nervoso periferico e le patologie primitive del muscolo. Le caratteristiche semeiologiche dell’amiotrofia, particolarmente importanti nella diagnosi di numerose patologie neuromuscolari, saranno esposte in questo articolo.

Structural colors arising from interactions of light with submicron scale periodic structures have been found in many species across all taxa, serving multiple biological functions including sexual signaling, camouflage, and aposematism. Directly inspired by the extensive use of self-assembled melanosomes to produce colors in avian feathers, we set out to synthesize and assemble polydopamine-based synthetic melanin nanoparticles in an effort to fabricate colored films. We have quantitatively demonstrated that synthetic melanin nanoparticles have a high refractive index and broad absorption spanning across the UV–visible range, similar to natural melanins. Utilizing a thin-film interference model, we demonstrated the coloration mechanism of deposited films and showed that the unique optical properties of synthetic melanin nanoparticles provide advantages for structural colors over other polymeric nanoparticles (i.e., polystyrene colloidal particles).

Methane‐producing hollow nanocubes: Hybrid CuO‐TiO2−xNxhollow nanocubes have been synthesized by first depositing TiO2onto Cu3N nanocube templates, then heating in air to oxidize the Cu3N to CuO while concomitantly incorporating nitrogen into the TiO2. The nanostructured CuO‐TiO2−xNxmaterial photocatalytically converts CO2into methane under solar irradiation.

Kubische Methanproduzenten: Hohle CuO‐TiO2−xNx‐Hybridnanowürfel wurden durch Abscheidung von TiO2auf Cu3N‐Nanowürfeltemplaten und anschließendes Erhitzen an Luft synthetisiert, um Cu3N zu CuO zu oxidieren und zugleich Stickstoff in TiO2zu inkorporieren. Das nanostrukturierte CuO‐TiO2−xNx‐Material wirkt unter Sonnenbestrahlung als Photokatalysator für die Umwandlung von CO2in Methan.

The availability of high-quality colloidal nanosheets underpins a diverse range of applications and investigations into dimension-dependent physical properties. To facilitate this, synthetic methods that yield single-crystal colloidal nanosheets with regular shapes, uniform lateral dimensions, and tunable thicknesses are critically important. Most strategies that yield colloidal nanosheets achieve some, but not all, of these morphological characteristics. Here, we describe a synthetic pathway that generates colloidal nanosheets of SnSe with uniform lateral dimensions and tunable thicknesses. SnSe represents an excellent prototype system for studying the formation of colloidal nanosheets because of its layered crystal structure and the growing interest in its potential application as an absorption layer in low-cost photovoltaic devices. Freestanding colloidal SnSe nanosheets were synthesized by slowly heating a one-pot reaction mixture of SnCl2, oleylamine, trioctylphosphine selenide (TOP-Se), and hexamethyldisilazane (HMDS) to 240 °C. The SnSe nanostructures adopt a uniform square-like morphology with lateral dimensions of approximately 500 nm ×500 nm, and the average nanosheet thicknesses can be tuned from approximately 10 to 40 nm by adjusting the concentrations of the SnCl2and TOP-Se reagents. Aliquot studies reveal fundamental insights into how the nanosheets form: they first “grow out” laterally viacoalescence of individual nanoparticle building blocks to yield a single-crystal nanosheet template and then “grow up” vertically (through nanoparticle attachment to the nanosheet template) in a pseudo layer-by-layer fashion. Vertical growth is therefore limited, and can be controlled, by reagent concentration. Drop-cast films of the SnSe nanosheets are photoactive and have a bandgap of approximately 1 eV. These studies, demonstrated for SnSe but potentially applicable to other systems, establish a straightforward pathway for tuning the thicknesses of colloidal nanosheets while maintaining lateral uniformity.

The effects of hydrogen on the growth kinetics of Si(0 0 1) during gas-source molecular-beam epitaxy from disilane are investigated with kinetic Monte Carlo simulations. The growth model includes the surface decomposition of disilane, which requires four mobile and reactive surface species: Si, H, SiH2and SiH3. Based on recent reflectance anisotropy measurements, the desorption of hydrogen is presumed to occur preferentially from step edges. Below approximately 400°C (where the model allows surface reactions to occur) the accumulation of surface hydrogen is found to prevent growth, but for temperatures above 600°C, where the surface lifetime of the hydrogen is relatively short, we find no significant differences in the overall growth features in comparison with a solid-source (no hydrogen) growth model of Si(0 0 1). At intermediate temperatures, where surface hydrogen atoms are present but do not prevent growth, we find a higher density of smaller islands and rougher propagating step edges in comparison with those of the solid-source model. Anisotropic morphological features, which are characteristic signatures in the solid-source model, are suppressed by the surface hydrogen atoms in the gas-source model.

Conflicting data have been reported regarding the presence or absence of a predominant variable (V) region T-cell receptor (TCR) gene in the peripheral blood or synovial fluid of patients with rheumatoid arthritis (RA). In this study we have used the polymerase chain reaction (PCR) to compare the level of TCR Vβ gene expression by peripheral blood mononuclear cells (PBMC) and by synovial fluid cells obtained from HLA DRB1 *0401 and *0404 RA patients. PCR was performed using cDNA synthesized from freshly obtained cells (not stimulated in vitro). The pattern of expression observed for most of the Vβ genes studied showed either preferential expression by PBMC or similar levels of expression between PBMC and synovial fluid T-cells. However, among individual patients (N = 5), several Vβ genes were identified that were expressed to a significantly greater degree by synovial fluid cells. Vβ14 expression was detected in PBMC of all patients and the level of transcripts encoding Vβ14 increased following stimulation with immobilized anti-CD3 and IL-2. In vitro manipulation of populations of T-cells was found to alter the level of expressed Vβ gene products. A Vβ gene common to all patients that was consistently deleted from PBMC or expressed to a greater degree by resident, unsorted synovial fluid cells compared to PBMC was not identified. Copyright 1993, 1999 Academic Press

Patients who have extensive stricture disease, those in whom hypospadias repair fails and those who sustain significant urethral trauma pose a reconstructive challenge for genitourinary surgeons. We developed an additional reconstructive option for men with a severely diseased urethra when grafting procedures and local tissue flaps have failed or are otherwise contraindicated.

The housing tube material of the marine worm Chaetopterussp.exhibits thermal stability up to 250°C, similar to other biological materials such as mulberry silkworm cocoons. Interestingly, however, dynamic mechanical thermal analysis conducted in both air and water elucidated the lack of a glass transition in the organic tube wall material. In fact, the viscoelastic properties of the anhydrous and undried tube were remarkably stable (i.e. constant and reversible) between –75°C and 200°C in air, and 5°C and 75°C in water, respectively. Moreover, it was found that hydration and associated-water plasticization were key to the rubber-like flexible properties of the tube; dehydration transformed the material behaviour to glass-like. The tube is made of bionanocomposite fibrils in highly oriented arrangement, which we argue favours the biomaterial to be highly crystalline or cross-linked, with extensive hydrogen and/or covalent bonds. Mechanical property characterization in the longitudinal and transverse directions ascertained that the tubes were not quasi-isotropic structures. In general, the higher stiffness and strength in the transverse direction implied that there were more nanofibrils orientated at ±45° and ±65° than at 0° to the tube axis. The order of the mechanical properties of the soft–tough tubes was similar to synthetic rubber-like elastomers and even some viscid silks. The complex structure–property relations observed indicated that the worm has evolved to produce a tubular housing structure which can (i) function stably over a broad range of temperatures, (ii) endure mechanical stresses from specific planes/axes, and (iii) facilitate rapid growth or repair.

The enhancer of human papillomavirus type 18 consists of two functionally redundant domains, one is partially conserved between HPV18 and HPV16, both mediate strong transcriptional enhancement. In contrast, short fragments of the enhancer mediate low transcriptional enhancement, suggesting that there Is functional cooperation between HPV enhancer binding factors. Previously interactions of the enhancer with NF-1, AP1 and steroid receptors were shown by EMSA. Here we show by binding site blotting, that four novel sequence specific proteins p110, p92, p42 and p40 bind to the enhancer. Nuclear proteins p110 and p92 bind at repeated sites In the enhancer, proteins p42 and p40 only at one site. Recognition sequences for p110 and p92 were identified in a TTGCTTGCATAA sequence motif and consist of an overlapping p110 and p92 recognition site. The specific interaction of p110 with G residues of this 12 nucleotlde long sequence was demonstrated by a mutant recognition site. Single recognition sites for p42 and p40 were localized in the enhancer by the use of overlapping oligonucleotides. In addition, electrophoretlc mobility shift analysis identified Oct-1 and AP2 interactions with the enhancer. The AP2 binding site was mapped to a AGGCACATATT motif. The p92 protein binds to enhancer oligonucleotides, containing at least one copy of Oct-1 like recognition sequences, these oligonucleotides also bind synthetic Oct-1 protein.During serum starvation or at high saturation density, p92 moves from the nucleus into the cytoplasm. Immunoblots of cytoplasmic extracts with anti-Oct-1 antisera showed, that p92 is a novel octamer binding factor, which is not immunologically related to the Oct-1 protein. The intracellular p92 distribution Is regulated at the G0/G1 boundary of the cell cycle, by nucleo-cytoplasmic translocation.

YB-1 cDNA clones were isolated by binding site screening of a Hela expression library using a human papillomavirus type 18 enhancer oligonucleotlde. YB-1 belongs to a family of transcription factors which bind to recognition sequences containing a core CCAAT element. YB-1 bound to its single stranded recognition sequence on the sense strand but not to the anti-sense strand. A synthetic peptide antiserum derived from the predicted YB-1 amino acid sequence identified a 42kD nuclear protein in immunoblots. A protein with the same size was detected by binding site blotting experiments using the HPV18 enhancer oligonucleotide which bound YB-1. YB-1 gene expression was restricted in tissues from a human 24 week old fetus. High levels of YB-1 mRNA were present in heart, muscle, liver, lung, adrenal gland and the brain, in contrast, low amounts of YB-1 mRNA were found in thymus, kidney, bone marrow and spleen. In pancreas, bladder, stomach and testis YB-1 mRNA could not be detected by Northern hybridization. Finally, we have identified four YB-1 related loci in the mouse genome and have mapped these loci to four different mouse chromosomes by interspecific backcross analysis.