Internal Structure Of Particles Research Articles

Impacts of Revised Quantum Electrodynamics on Fundamental Physics

A revised quantum electrodynamic theory by the author is reconsidered, in respect to the basic concepts established by M. Planck and H.B.G. Casimir on the Zero Point Energy (ZPE) and by A. Einstein on Special Relativity. Attention is given to the new properties of its field equations and their applications. These equations include results not being available from conventional theory and the Standard Model. This concerns the internal structure of elementary particles, such as the photon, the electron, muon and tauon, the Z boson, and the so called Higgs particle detected in the experiments at the laboratory of CERN. A possible unification of electrodynamics and the strong nuclear force is further provided by the theory. Finally, there are aspects on the expanding universe represented by a new interpretation of dark matter and dark energy in terms of the ZPE.

Calcium based sorbent calcination and sintering reaction models overview

Several models considering the pulverized sorbent reactions with pollutant gases were developed over the past years. In this paper, we present a detailed overview of available models for direct furnace injection of pulverized calcium sorbent suitable for potential application in CFD codes, with respect to implementation difficulty and computational resources demand. Depending on the model, variations in result accuracy, data output, and computational power required may occur. Some authors separate the model of calcination reaction, combined with the sintering model, and afterwards model the sulfation. Other authors assume the calcination to be instantaneous, and focus the modelling efforts toward the sulfation reaction, adding the sintering effects as a parameter in the efficiency coefficient. Simple models quantify the reaction effects, while more complex models attempt to describe and explain internal particle reactions through different approaches to modelling of the particle internal structure.

Synthesis of Poly(N-vinylcaprolactam)-Based Microgels by Precipitation Polymerization: Process Modeling and Experimental Validation

The successful application of poly(N-vinylcaprolactam)-based microgels requires a profound understanding of their synthesis. For this purpose, a validated process model for the microgels synthesis by precipitation copolymerization with the cross-linker N,N′-methylenebis(acrylamide) is formulated. Unknown reaction rate constants, reaction enthalpies, and partition coefficients are obtained by quantum mechanical calculations. The remaining parameter values are estimated from reaction calorimetry and Raman spectroscopy measurements of experiments with different monomer/cross-linker compositions. Because of high cross-propagation reaction rate constants, simulations predict a fast incorporation of the cross-linker. This agrees with reaction calorimetry measurements. Furthermore, the gel phase is predicted as the major reaction locus. The model is utilized for a prediction of the internal particle structure regarding its cross-link distribution. The highly cross-linked core reported in the literature correspon...

Comparison of Seven Texture Analysis Indices for Their Applicability to Stereological Correction of Mineral Liberation Assessment in Binary Particle Systems

An effective correction method for stereological bias is required because of the importance of accurate assessment of mineral liberation of ore particles. Stereological bias is error caused by the estimation of a three-dimensional liberation state based on two-dimensional sectional measurements. Recent studies have proposed a stereological correction method based on sectional particle texture analysis, which employs numerical particle models. However, the applicability of this method to unfamiliar particle systems, with different shape and texture characteristics from the numerical particle model, has not been thoroughly investigated. In this study, the viability of the method for examination of the internal structure and shape of unfamiliar particles, was assessed using four types of particle systems, based on combinations of two types of internal structures (Boolean and Voronoi) and two types of particle shapes (spherical and irregular). Seven different texture analysis indices were utilized for composition distribution correction with regard to each of the four types of particle systems. The results suggested that a model based on the angular second moment and/or entropy, employed by the spatial gray level dependence method, showed the greatest viability for assessment of unfamiliar particle internal structure and/or shape.

Preparation of core-shell microspheres of lactose with flower-like morphology and tailored porosity

Flower-like lactose microparticles with tailored porosity on the core and the shell have been synthesized using sugars, such as sucrose, glucose and fructose as templating agents. The proposed mechanism for tailoring the porosity is based on the difference in the diffusion coefficients of templating sugars compared with that of lactose as the core material, resulting in the migration of template molecules to the core or the shell of spray-dried particles during the spray-drying process. Focused ion beam (FIB) and scanning electron microscopy (SEM) techniques have been used to investigate the internal structure of the porous lactose particles. It has been found that using sucrose, with a lower diffusion coefficient compared with lactose, resulted in a porous shell upon template removal by ethanol washing, since lactose molecules with higher diffusivity tend to migrate to the core. By contrast, glucose and fructose, with higher diffusion coefficients, led to a porous core due to their tendency to accumulate in the core of the spray-dried particles. Nitrogen physisorption tests showed that the flower-like lactose microspheres have a large surface area of 26–31m2/g and a high pore volume of 0.57–0.78cm3/g with a pore size distribution predominantly in the micro- and mesoporous range (1.6, 3.8 and 30nm). The pore size distributions of these flower-like lactose microparticles show that fructose, with the lowest glass-transition temperature (Tg) and consequently the highest crystallization rate during spray drying gave in larger pores, while the sucrose with the highest Tg led to smaller pores.

Uncovering the local inelastic interactions during manufacture of ductile cast iron: How the substructure of the graphite particles can induce residual stress concentrations in the matrix

Recent X-ray diffraction (XRD) measurements have revealed that plastic deformation and a residual elastic strain field can be present around the graphite particles in ductile cast iron after manufacturing, probably due to some local mismatch in thermal contraction. However, as only one component of the elastic strain tensor could be obtained from the XRD data, the shape and magnitude of the associated residual stress field have remained unknown. To compensate for this and to provide theoretical insight into this unexplored topic, a combined experimental-numerical approach is presented in this paper. First, a material equivalent to the ductile cast iron matrix is manufactured and subjected to dilatometric and high-temperature tensile tests. Subsequently, a two-scale hierarchical top-down model is devised, calibrated on the basis of the collected data and used to simulate the interaction between the graphite particles and the matrix during manufacturing of the industrial part considered in the XRD study. The model indicates that, besides the viscoplastic deformation of the matrix, the effect of the inelastic deformation of the graphite has to be considered to explain the magnitude of the XRD strain. Moreover, the model shows that the large elastic strain perturbations recorded with XRD close to the graphite–matrix interface are not artifacts due to e.g. sharp gradients in chemical composition, but correspond to residual stress concentrations induced by the conical sectors forming the internal structure of the graphite particles. In contrast to common belief, these results thus suggest that ductile cast iron parts cannot be considered, in general, as stress-free at the microstructural scale.

Effect of Particle Shape, Density, and Inhomogeneity on the Microwave Optical Properties of Graupel and Hailstones

Atmospheric ice particles can be rimed and contaminated (e.g., by soot attachments). Previous optical property calculations usually assume rimed particles such as graupel and hailstones to be homogeneous spheres with fixed densities. The relevant dielectric constants are estimated with the effective medium approximation (EMA), although such particles are predominately nonspherical, porous, and contain small interior grains. This paper assesses the effects of nonsphericity, density, and inhomogeneity of graupel and hailstones on their optical properties. The bicontinuous medium approximation (BMA) is employed to simulate the particle internal structure. Conical shapes are compared with spherical and spheroidal shapes to assess the effect of nonsphericity. At frequencies lower than 89 GHz, the optical properties are more sensitive to particle’s mass density than to overall particle shape, and the internal structure plays an insignificant role when the particle effective diameter (a quantity involving the particle size distribution) is smaller than approximately 10 mm, and the internal grain size is smaller than 0.2 mm. With a small grain size, the BMA phase function converges to the EMA phase function with an effective refractive index calculated with the Bruggeman formulation. Simulated top of atmosphere radiances at three microwave frequencies, 18.7, 36.5, and 89 GHz, are quite sensitive to ice particle effective diameter between 1 and 5 mm, ice fraction between 0.1 and 0.9, and ice water path between 1 and 5 kg/ $\text{m}^{2}$ . Thus, these frequencies are suitable for retrieving the microphysical properties.

Features of light absorption by an ensemble of microcapsules

Features of laser radiation scattering and absorption by an ensemble of two identical microcapsules are theoretically studied. Each capsule is modeled by a two-layer spherical micron-size particle consisting of water core and light absorbing polymer shell. By the numerical electrodynamics techniques, it is shown that the internal structure and mutual arrangement of particles affect the spatial distribution and amplitude characteristics of the power absorbed. The highest values of the absorbed power density in model microcapsules could be attained if the particles are shifted relative to each other by a distance of about their diameter (strongly absorbing particles) or if the particles are in the geometric shadow of each other (weak absorption).

Semiclassics for matrix Hamiltonians: The Gutzwiller trace formula with applications to graphene-type systems

We present a tractable and physically transparent semiclassical theory of matrix-valued Hamiltonians, i.e., those that describe quantum systems with internal degrees of freedoms, based on a generalization of the Gutzwiller trace formula for a $n\ifmmode\times\else\texttimes\fi{}n$ dimensional Hamiltonian $H(\stackrel{\ifmmode \hat{}\else \^{}\fi{}}{\mathbf{p}},\stackrel{\ifmmode \hat{}\else \^{}\fi{}}{\mathbf{q}})$. The classical dynamics is governed by $n$ Hamilton-Jacobi (HJ) equations that act in a phase space endowed with a classical Berry curvature encoding anholonomy in the parallel transport of the eigenvectors of $H(\mathbf{p},\mathbf{q})$; these vectors describe the internal structure of the semiclassical particles. At the $\mathcal{O}({\ensuremath{\hbar}}^{1})$ level and for nondegenerate HJ systems, this curvature results in an additional semiclassical phase composed of (i) a Berry phase and (ii) a dynamical phase resulting from the classical particles ``moving through the Berry curvature''. We show that the dynamical part of this semiclassical phase will, generally, be zero only for the case in which the Berry phase is topological (i.e., depends only on the winding number). We illustrate the method by calculating the Landau spectrum for monolayer graphene, the four-band model of AB bilayer graphene, and for a more complicated matrix Hamiltonian describing the silicene band structure. Finally, we apply our method to an inhomogeneous system consisting of a strain engineered one-dimensional moir\'e in bilayer graphene, finding localized states near the Dirac point that arise from electron trapping in a semiclassical moir\'e potential. The semiclassical density of states of these localized states we show to be in perfect agreement with an exact quantum mechanical calculation of the density of states.

Trends in analysis of gunshot residue for forensic purposes.

Detection and identification of organic and inorganic components of gunshot residue are well established within forensic chemistry because of highly characteristic and uncommon features of the products of ammunition discharge at the time and place of a shooting incident in comparison to other materials present in daily life of people. Both types of residue play an important role in establishing various circumstances of a shooting crime, though the most vital one concerns the possibility of relating a suspect with the activity of shooting. In this aspect, solid, inorganic particles, nowadays called characteristic, have been utilized. Their specific features result from the primer mixture composition, including compounds of heavy metals, lead, antimony, and barium, and from the extraordinarily dynamic conditions of their formation, taking place at the moment of the primer detonation. Scanning electron microscopy and X-ray microanalysis techniques proved to be necessary and sufficient to reveal the content and the spherical morphology of the particles for this purpose. Recently, the recommendation that the potential for lead exposure be minimized was followed in the production of ammunition cal. 9mm Luger, 0.40S&W, 0.380 Auto, and 0.38 Special. These modern types of ammunition expel less characteristic particles, the identification of which can be a challenge for the examiners. At least two solutions to strengthen the residue identity are taken into account: additional insights into the internal structure of inorganic particles, e.g., by means of electron backscattered diffraction and focused ion beam, as well as complementary examinations of organic residues with sensitive mass spectrometric techniques.

Research of the possibility of using an electrical discharge machining metal powder in selective laser melting

In this paper the research of a Ni-20Cr-10Fe-3Ti (heat-resistant) alloy metal powder conducted for use in a selective laser melting technology. This metal powder is the slime after electric discharge machining. The technology of cleaning and melting the powder discussed in this article. As a control input of the powder, immediately before 3D printing, dimensional analysis, surface morphology and the internal structure of the powder particles after the treatment were examined using optical and electron microscopes. The powder granules are round, oval, of different diameters with non-metallic inclusions. The internal structure of the particles is solid with no apparent defects. The content of the required diameter of the total volume of test powder granules was 15%. X-ray fluorescence analysis of the powder materials carried out. The possibility of powder melting was investigated in the selective laser melting machine ‘SLM 280HL’. A selection of the melting modes based on the physical properties of the Ni-20Cr-10Fe-3Ti alloy, data obtained from similar studies and a mathematical model of the process. Conclusions on the further investigation of the possibility of using electric discharge machining slime were made.

Quantum Mechanics, vacuum, particles, Gödel-Cohen incompleteness and the Universe

Are the standard laws of Physics really fundamental principles? Does the physical vacuum have a more primordial internal structure? Are quarks, leptons, gauge bosons… ultimate objects? These three basic questions are actually closely related. If the deep vacuum structure and dynamics turn out to be less trivial than usually depicted, the conventional elementary particles will most likely be excitations of such a vacuum dynamics that remains by now unknown. We then expect relativity and quantum mechanics to be low-energy limits of a more fundamental dynamical pattern that generates them at a deeper level. It may even happen that vacuum drives the expansion of the Universe from its own inner dynamics. Inside such a vacuum structure, the speed of light would not be the critical speed for vacuum constituents and propagating signals. The natural scenario would be the superbradyon (superluminal preon) pattern we postulated in 1995, with a new critical speed c s much larger than the speed of light c just as c is much larger than the speed of sound. Superbradyons are assumed to be the bradyons of a super-relativity associated to c s (a Lorentz invariance with c s as the critical speed). Similarly, the standard relativistic space-time with four real coordinates would not necessarily hold beyond low-energy and comparatively local distance scales. Instead, the spinorial space-time (SST) with two complex coordinates we introduced in 1996-97 may be the suitable one to describe the internal structure of vacuum and standard elementary particles and, simultaneously, Cosmology at very large distance scales. If the constituents of the preonic vacuum are superluminal, quantum entanglement appears as a natural property provided c s ≫ c . The value of c s can even be possibly found experimentally by studying entanglement at large distances. It is not excluded that preonic constituents of vacuum can exist in our Universe as particles (free superbradyons), in which case we expect them to be weakly coupled to standard matter. If a preonic vacuum is actually leading the basic dynamics of Particle Physics and Cosmology, and standard particles are vacuum excitations, the Godel-Cohen incompleteness will apply to vacuum dynamics whereas the conventional laws of physics will actually be approximate and have error bars. We discuss here the possible role of the superbradyonic vacuum and of the SST in generating Quantum Mechanics, as well as the implications of such a dynamical origin of the conventional laws of Physics and possible evidences in experiments and observations. Black holes, gravitational waves, possible free superbradyons or preonic waves, unconventional vacuum radiation… are considered from this point of view paying particular attention to LIGO, VIRGO and CERN experiments. This lecture is dedicated to the memory of John Bell

Викиди зважених часток від повітряних суден під час експлуатації в межах аеропорту

Мета: Викиди авіадвигунів в межах приземного граничного шару під час етапів зльоту та посадки призводять до значного погіршення якості повітря в межах аеропорту та на прилеглих житлових територіях. На сьогодні, основними об'єктами забруднення повітря в аеропортах є оксиди азоту і зважені частки (ЗЧ10, ЗЧ2.5 і ультрадісперсні ЗЧ), які спричиняють виникнення відповідно фотохімічного смогу та туману з наступними несприятливими наслідками для здоров’я населення. Аналіз результатів інвентаризації викидів ЗЧ у головних аеропортах Європи вказує на домінантність викидів авіадвигунів та допоміжної силової установки. Стаття спрямована на аналіз теоретичних та експериментальних досліджень із розподілу часток за розміром у викидах авіадвигунів, а також особливостей їх морфології та внутрішньої структури, оскільки зазначені властивості мають важливе значення для розуміння потенційного впливу ЗЧ на здоров'я населення. Стаття також надає детальний опис основних методів розрахунку викидів та дисперсії ЗЧ від авіадвигуна протягом злітно-посадкового циклу повітряного судна. Методи: аналітичне розв'язання рівняння атмосферної дифузії використовується для розрахунку максимальної концентрації ЗЧ від точкового джерела емісії. Концентрація ЗЧ змінюється обернено пропорційно швидкості вітру u1 і прямо пропорційно вертикальній складовій коефіцієнту турбулентного обміну k1/u1. Оцінка концентрації нелетучої ЗЧ враховує розмір і форму ЗЧ. Модель PolEmiCa обчислює розподіл фракцій ЗЧ у викидах від авіадвигунів та ДСУ (висота установки H = 4,5 м для Ту-154). Результати: Максимальна концентрація ЗЧ у викидах ДСУ вища, а відповідна відстань менша, у порівнянні з випадком для газу. Полідисперсність призводить до розподілу максимумів концентрацій в просторі для окремих фракцій за напрямком вітру, що призводить до зменшення загальної максимальної концентрації. Обговорення: Хоча емісія ДСУ сягає рівня авіадвигунів, викиди ДСУ не сертифіковані ІСАО. Отже, зазначена проблема є актуальною для місцевої якості повітря, зокрема для розробки моделі та визначення методів виявлення складової викидів авіадвигунів і ДСУ у загальне забруднення повітря аеропорту ЗЧ.

Inkjet Printed Polyelectrolytes for Microfluidic Paper-based Analytical Devices

Paper-based microfluidic devices can provide practical analytics platforms for applications such as point-of-care medical diagnostics. So far immobilisation or separation of analytes on such devices has received limited attention. This study introduces inkjet printed polyelectrolyte patterns as possible platforms for immobilisation of cationic and anionic compounds through surface charge interaction. Both cationic (polydiallyldimethylammonium chloride) and anionic (sodium polyacrylate) polyelectrolytes were inkjet printed on a custom designed porous pigment coating, having fine particle internal pore structure to ensure high surface contact between the analytical sample and modified pore walls. Printed polyelectrolyte patterns were themselves largely invisible, including under UV light. In a proof of principle test, a controllable degree of separation of anionic Uranine and Tartrazine dyes from aqueous solution passing through a printed cationic polyelectrolyte region could be observed. However, weakly cationic Rhodamine B could not be captured on anionic regions.

Mechanistic Studies on the Self-Assembly of PLGA Patchy Particles and Their Potential Applications in Biomedical Imaging.

Currently, several challenges prevent poly(lactic-co-glycolic acid) (PLGA) particles from reaching clinical settings. Among these is a lack of understanding of the molecular mechanisms involved in the formation of these particles. We have been studying in depth the formation of patchy polymeric particles. These particles are made of PLGA and lipid-polymer functional groups. They have unique patch-core-shell structural features: hollow or solid hydrophobic cores and a patchy surface. Previously, we identified the shear stress as the most important parameter in a patchy particle's formation. Here, we investigated in detail the role of shear stress in the patchy particle's internal and external structure using an integrative experimental and computational approach. By cross-sectioning the multipatch particles, we found lipid-based structures embedded in the entire PLGA matrix, which represents a unique finding in the PLGA field. By developing novel computational fluid dynamics and molecular dynamics simulations, we found that the shear stress determines the internal structure of the patchy particles. Equally important, we discovered that these particles emit a photoacoustic (PA) signal in the optical clinical imaging window. Our results show that particles with multiple patches emit a higher PA signal than single-patch particles. This phenomenon most likely is due to the fact that multipatchy particles absorb more heat than single-patchy particles as shown by differential scanning calorimetry analysis. Furthermore, we demonstrated the use of patchy polymeric particles as photoacoustic molecular probes both in vitro and in vivo studies. The fundamental studies described here will help us to design more effective PLGA carriers for a number of medical applications as well as to accelerate their medical translation.

Entangled Harmonic Oscillators and Space-Time Entanglement

The mathematical basis for the Gaussian entanglement is discussed in detail, as well as its implications in the internal space-time structure of relativistic extended particles. It is shown that the Gaussian entanglement shares the same set of mathematical formulas with the harmonic oscillator in the Lorentz-covariant world. It is thus possible to transfer the concept of entanglement to the Lorentz-covariant picture of the bound state, which requires both space and time separations between two constituent particles. These space and time variables become entangled as the bound state moves with a relativistic speed. It is shown also that our inability to measure the time-separation variable leads to an entanglement entropy together with a rise in the temperature of the bound state. As was noted by Paul A. M. Dirac in 1963, the system of two oscillators contains the symmetries of the O ( 3 , 2 ) de Sitter group containing two O ( 3 , 1 ) Lorentz groups as its subgroups. Dirac noted also that the system contains the symmetry of the S p ( 4 ) group, which serves as the basic language for two-mode squeezed states. Since the S p ( 4 ) symmetry contains both rotations and squeezes, one interesting case is the combination of rotation and squeeze, resulting in a shear. While the current literature is mostly on the entanglement based on squeeze along the normal coordinates, the shear transformation is an interesting future possibility. The mathematical issues on this problem are clarified.

Selective Sequence for the Peptide-Triggered Phase Transition of Lyotropic Liquid-Crystalline Structures.

A novel concept of using mixed lipids to construct selective peptide-sequence-sensing lyotropic liquid-crystalline (LLC) dispersion systems was investigated. The LLC systems were constructed using a mixture of phytantriol, a lipid that forms lyotropic liquid-crystalline phases, and a novel synthesized peptide-lipid (peplipid) for sensing a target peptide with the RARAR sequence. The internal structure of the dispersed LLC particles was converted from the lamellar structure (liposomes) to the inverse bicontinuous cubic phase (cubosomes) in the presence of the target peptide. The addition of common human proteins did not induce any structural change, indicating a high selectivity of interaction with the target peptide. The concept has potential for the design of targeted controlled release drug delivery agents.

Analysis of the chemical features of particles generated from ethylene and ethylene/2,5 dimethyl furan flames

Carbon particulate matter formed in fuel-rich atmospheric pressure premixed flames of ethylene and ethylene doped with 2,5 dimethyl furan (DMF) (20%) was analyzed in order to investigate the effect of fuel-borne oxygen on soot nanostructure and chemical functionalities. Particles were thermophoretically sampled on quartz plates and analyzed by techniques sensitive to the particle internal structure, namely FTIR, Raman and UV–vis spectroscopy. In nearly identical temperature, equivalence ratio and residence time conditions, the concentration of particulate generated in the biofuel-doped flame was found to be far less of the concentration of ethylene flame particulate. The similarity of UV–vis and Raman spectra showed that DMF addition to ethylene did not significantly change the aromatization process of carbon particulate in the flame. Complementary information on the functional groups located at the edge of the polyaromatic system was probed by FTIR analysis. FTIR spectra showed to be very similar regarding the carbon network in particles produced in both flames. However, the infrared spectrum of the particles produced in the ethylene/DMF flame presented less intense peaks of aromatic hydrogen (900–700cm−1) and a higher absorption in the 1300–1100cm−1 wavenumber range. These changes in the infrared spectra were attributed to a higher amount of oxygen atoms that substitute hydrogen atoms at the edges of aromatic clusters of the ethylene/DMF soot particles. Oxygen content was estimated to be larger by few percentages in particles from ethylene/DMF with respect to particles from pure ethylene. This could be the cause for the enhanced reactivity of soot particles generally found for biofuel-derived soot.

Exact and near backscattering measurements of the linear depolarisation ratio of various ice crystal habits generated in a laboratory cloud chamber

Ice clouds were generated in the Manchester Ice Cloud Chamber (MICC), and the backscattering linear depolarisation ratio, δ, was measured for a variety of habits. To create an assortment of particle morphologies, the humidity in the chamber was varied throughout each experiment, resulting in a range of habits from the pristine to the complex. This technique was repeated at three temperatures: −7°C, −15°C and −30°C, in order to produce both solid and hollow columns, plates, sectored plates and dendrites. A linearly polarised 532nm continuous wave diode laser was directed through a section of the cloud using a non-polarising 50:50 beam splitter. Measurements of the scattered light were taken at 178°, 179° and 180°, using a Glan–Taylor prism to separate the co- and cross-polarised components. The intensities of these components were measured using two amplified photodetectors and the ratio of the cross- to co-polarised intensities was measured to find the linear depolarisation ratio. In general, it was found that Ray Tracing over-predicts the linear depolarisation ratio. However, by creating more accurate particle models which better represent the internal structure of ice particles, discrepancies between measured and modelled results (based on Ray Tracing) were reduced.

Sculpting the internal architecture of fluorescent silica particles via a template-free approach

Particles with an open, porous structure can be used to deliver payloads. It is often of interest to detect such particles in tissue or materials, which is facilitated by addition of dye. A straightforward approach leading to fluorescent, porous silica particles is described. The particles are etched with 3mM aqueous sodium hydroxide, taking advantage of the etching rate difference between normal silica and an interior band of silica that contains covalently attached dye. No additional steps, such as dye labeling or thermal annealing, are required. Etching modeled the internal structure of the fluorescent silica particles by creating meso/macropores and voids, as reflected by nitrogen absorption measurements. In order to investigate whether a polymer shell influences etching, certain composite particles are top-coated with poly(l-lysine) representing neutral or positive charged surfaces under typical pH conditions in living systems. The polypeptide-coated fluorescent silica cores exhibit the same porous morphology as uncoated homologs. The polypeptide topcoat does little to alter the permeation by the etching agent. Preservation of size during etching, confirmed by dynamic light scattering, transmission electron microscopy and small-angle X-ray scattering, simplifies the use of these template-free porous fluorescent particles as platforms for drug encapsulation, drug carriers and in vivo imaging.