Mesoporous silica nanoparticles (MSNPs) are synthesized in the various forms of porous structures according to an application’s needs, while their zeta potentials play a major role in their function. We show that variation in pore size and/or porosity yields a substantial decrease in MSNP zeta potential up to 25% lower than the theoretical zeta potential predictions for a flat surface at the corresponding ionic conditions in moderate pH range. By considering surface chemistry as a function of local ionic conditions (charge regulation), we calculated local zeta potentials around the MSNP which showed variation between pore openings and solid surfaces. Through a systematic study, we evaluated an average three-dimensional zeta potential for MSNPs with various conditions, based on the ratio of the area covered by pore openings to the rest of the MSNP surface area as a function of three-dimensional porosity and pore size. Results show that the high overlap of ionic layers inside the pores creates electric potentials close to zeta potential of the remaining surface, but large pore size and/or high ionic salt concentration yields divergence. We characterized the variation of MSNP zeta potential in terms of porosity (ε 3D), pore size (D pore), and ionic condition quantified by Debye length (λ) and obtained unified behavior as a function of the nondimensional group of ε 3D(D pore/λ). For ε 3D(D pore/λ) < 0.01, MSNP zeta potential remains similar to flat plate predictions, but it decreases by increasing ε 3D(D pore/λ) value. The influence of pore entrances on surface zeta potential increases nonlinearly by the increase of porosity and/or decrease of EDL overlap, similar to a change of area to volume ratio. The current findings are important for the understanding and further control of mesoporous particle transport in various promising and groundbreaking applications such as targeted drug delivery.

Transport inside nano-channels and tubes is highly dependent on their surface charge properties. While previous studies assume that the charge density of a surface is a material property and independent of confinement size, this study properly characterized the surface charge of a nanochannel as a function of channel height and length under various solution conditions. By calculating the local surface charge based on local ionic concentrations, the surface charge of a nano-channel was studied by considering the effects of both overlapping electrical double layers (EDLs) and inlet/outlet regions. First, the surface charge of silica decreased with the increase in EDL overlap, which is characterized by the ratio of EDL thickness to channel height. Second, the local surface charge showed variation at the inlet/outlet regions where the channel's electrokinetics was in development. We defined a general entrance length as a function of EDL thickness for the electrokinetically developing part of different cases, after which the surface charge reached its equilibrium value and remained constant. Based on such length scales, we extended the existing theory to include nano-effects. A phenomenological model was developed, which can predict the average nano-channel surface charge as a function of EDL thickness, pH, channel length and channel height.

Mesoporous silica is an emerging technology to solve problems of existing and to support projected revolutionary applications ranging from targeted drug delivery to artificial kidney. However, one of the major driving mechanisms, electric charging of internal mesoporous surfaces, has not been characterized yet. In the nanoscale confinements of mesoporous structures made of pore throats and pore voids, surface charges diverge from existing theoretical calculations and show local variation due to two occurrences. First, when the size of pore throat becomes comparable with the thickness of ionic layering forming on throats’ surfaces, ionic layers from opposite surfaces overlap so that ionic concentration on the surface becomes different than Boltzmann distribution predicts, and there will no longer be an equilibrium of zero electric potential at pore throat centers. Second, when this non zero potential inside throats becomes different than the potential of pore voids, ionic diffusion from void to throat creates axial ionic variation on surfaces. For such a case, we performed a pore level analysis on mesoporous internal surface charge at various porosities and ionic conditions. Pore parameters strongly affected the average internal charge which we characterized as a function of overlap ratio and porosity, first time in literature. Using this, a phenomenological model was developed as an extension of the existing theory to include nano-effects, to predict the average mesoporous internal surface charge as a function of EDL thickness, pore size and porosity.

Nano-scale confinements within mesoporous systems develop overlapping electric double layers (EDL) such that the existing theoretical models cannot predict the electric potential distributions and resulting surface charges. In addition, ionic conditions undergo local variation through connections between the pore voids and pore throats. For the first time in literature, we studied the charging behavior of mesoporous silica in terms of the pore to throat size ratio (R pt ) to characterize the pore connectivity effects, in addition to porosity (є) and pore size (H). Both local and average surface charge densities inside mesoporous silica were examined by varying these parameters systematically. Results showed that the magnitude of surface charge density decreased with increasing EDL overlap and decreasing connectivity effects. We formulized this behavior and developed an extended model to predict mesoporous silica's internal charge as a function of porosity, pore size, and pore to throat size ratio.

Bu çalışma, bulanık mantık algoritması oluşturularak, örnek seçilen devlet hastanelerinin hasta bakım ve tedavi alanlarının tasarım verimliliklerine göre sınıflandırılması için yürütülmüştür. Hasta bakım ve tedavi ünitelerinin kat planlarından hasta kullanım alanları ve dolaşım alanları elde edilerek bulanık mantık modeli alt kümeleri için üyelik fonksiyonları oluşturulmuştur. Girdi değişkenleri olarak hasta kullanım alanları ve dolaşım alanları modellenmiştir. Girdi değişkenleri ile çıktı değişkeni olan tasarım verimliliği arasındaki ilişkiler bulanık mantık kuralları ile ortaya çıkarılmıştır. Mevcut olan hasta bakım ünitelerini incelemek için, verimlilik çıktı değerleri modelden elde edilmiştir. Genel tasarım normları, tasarım kriterleri ve önceki çalışmalar ışığında ve de bu model aracılığıyla verimlilik sınıfları oluşturulmuştur. Verimlilik sınıflandırılması hastanelerin karşılaştırılarak incelenmesiyle sonuçlanmıştır.