Universality in the three-dimensional random bond quantum Heisenberg antiferromagnet

The three-dimensional quenched random bond diluted $(J_1-J_2)$ quantum Heisenberg antiferromagnet is studied on a simple-cubic lattice. Using extensive stochastic series expansion quantum Monte Carlo simulations, we perform very long runs for $L \times L \times L$ lattice up to $L=48$. By employing standard finite-size scaling method, the numerical values of the N\'eel temperature are determined with high precision as a function of the coupling ratio $r=J_2/J_1$. Based on the estimated critical exponents, we find that the critical behavior of the considered model belongs to the pure classical $3D$ $O(3)$ Heisenberg universality class.Comment: 8 pages, 7 figure

Retinal neurodegeneration in metabolic syndrome: a spectral optical coherence tomography study

• AIM: To evaluate the effects of metabolic syndrome (MetS) on retinal neurodegeneration by optical coherence tomography (OCT). • METHODS: Patients diagnosed as MetS were compared with the age and sex-matched healthy control group (CG). Waist circumference measurements, fasting serological biochemical tests, and systemic blood pressures of all participants were evaluated. The MetS group was divided into 3 subgroups according to the number of MetS components: hypertension, diabetes mellitus, dyslipidemia (low-, high-density lipoprotein, hypertriglyceridemia), and visceral obesity findings; 3-component MetS3, 4-component MetS4, and all-component MetS5. All patients underwent complete eye examination and spectral OCT retinal imaging. • RESULTS: Totally 58 eyes of 58 patients were included in the MetS group and 63 eyes of 63 age and sex-matched healthy subjects were included in CG. MetS group was composed of 22 subjects in MetS3, 21 subjects in MetS4, and 15 subjects in the MetS5 subgroup. Mean foveal thickness (MetS, 218.7±23.1 µm vs CG, 228.8±21.9 µm, P=0.015), mean inferior (MetS, 283.4±17.0 µm vs CG, 288.7±38.4 µm, P=0.002), superior (MetS, 287.0±18.5 µm vs CG 297.3±17.1 µm, P=0.001), nasal (MetS 287.3±16.7 µm vs CG 297.9±13.9 µm, P=0.000) and temporal (274.5±17.6 µm vs CG 285.6±13.6 µm, P=0.000) thickness in the 3 mm Early Treatment of Diabetic Retinopathy Study (ETDRS) circle was significantly lower in the MetS group. There was no statistically significant difference in the mean inferior, superior, nasal, and temporal thickness of 6 mm ETDRS circle, total macular volume, peripapillary and macular retinal nerve fiber layer, macular ganglion cell layer with inner plexiform layer, and ganglion cell complex. No statistically significant difference was found in these values between the MetS3, MetS4, and the MetS5 groups. • CONCLUSION: A significant reduction in central macular region thickness in MetS is detected and macular thickness is more susceptible to MetS induced neurodegeneration than peripapillary retinal nerve fiber layer. © 2023 International Journal of Ophthalmology (c/o Editorial Office). All rights reserved.Authors’ contributions: Polat E was responsible for designing the study protocol, supervision the study, conducting the search, screening potentially eligible studies, data collection, updating reference lists, and creating all tables. Celik E was responsible for designing the study protocol, contributed to writing the report, extracting and analyzing data, interpreting results, and creating all tables. Togac M was responsible for writing the protocol and report, contributed to data extraction, and provided feedback on the report. Sahin A was responsible for writing the literature review, data collection

Ultrasound-mediated transdermal drug delivery: Mechanisms, scope, and emerging trends

The use of ultrasound for the delivery of drugs to, or through, the skin is commonly known as sonophoresis or phonophoresis. The use of therapeutic and high frequencies of ultrasound (≥ 0.7 MHz) for sonophoresis (HFS) dates back to as early as the 1950s, while low-frequency sonophoresis (LFS, 20–100 kHz) has only been investigated significantly during the past two decades. Although HFS and LFS are similar because they both utilize ultrasound to increase the skin penetration of permeants, the mechanisms associated with each physical enhancer are different. Specifically, the location of cavitation and the extent to which each process can increase skin permeability are quite dissimilar. Although the applications of both technologies are different, they each have strengths that could allow them to improve current methods of local, regional, and systemic drug delivery. In this review, we will discuss the mechanisms associated with both HFS and LFS, specifically concentrating on the key mechanistic differences between these two skin treatment methods. Background on the relevant physics associated with ultrasound transmitted through aqueous media will also be discussed, along with implications of these phenomena on sonophoresis. Finally, a thorough review of the literature is included, dating back to the first published reports of sonophoresis, including a discussion of emerging trends in the field.National Institutes of Health (U.S.) (Grant EB-00351)Massachusetts Institute of Technology. Institute for Soldier Nanotechnologies (Grant DAAD-19-02-D-002

A physical mechanism to explain the delivery of chemical penetration enhancers into skin during transdermal sonophoresis — Insight into the observed synergism

The synergism between low-frequency sonophoresis (LFS) and chemical penetration enhancers (CPEs), especially surfactants, in transdermal enhancement has been investigated extensively since this phenomenon was first observed over a decade ago. In spite of the identifying that the origin of this synergism is the increased penetration and subsequent dispersion of CPEs in the skin in response to LFS treatment, to date, no mechanism has been directly proposed to explain how LFS induces the observed increased transport of CPEs. In this study, we propose a plausible physical mechanism by which the transport of all CPEs is expected to have significantly increased flux into the localized-transport regions (LTRs) of LFS-treated skin. Specifically, the collapse of acoustic cavitation microjets within LTRs induces a convective flux. In addition, because amphiphilic molecules preferentially adsorb onto the gas/water interface of cavitation bubbles, amphiphiles have an additional adsorptive flux. In this sense, the cavitation bubbles effectively act as carriers for amphiphilic molecules, delivering surfactants directly into the skin when they collapse at the skin surface as cavitation microjets. The flux equations derived for CPE delivery into the LTRs and non-LTRs during LFS treatment, compared to that for untreated skin, explain why the transport of all CPEs, and to an even greater extent amphiphilic CPEs, is increased during LFS treatment. The flux model is tested with a non-amphiphilic CPE (propylene glycol) and both nonionic and ionic amphiphilic CPEs (octyl glucoside and sodium lauryl sulfate, respectively), by measuring the flux of each CPE into untreated skin and the LTRs and non-LTRs of LFS-treated skin. The resulting data shows very good agreement with the proposed flux model.National Institutes of Health (U.S.) (Grant EB-00351)Massachusetts Institute of Technology. Institute for Soldier Nanotechnologies (Grant DAAD-19-02-D-002

Structural, optical and magnetic properties of Zn1−xMnxO micro-rod arrays synthesized by spray pyrolysis method

Undoped and Mn-doped ZnO micro-rod arrays were fabricated by the spray pyrolysis method on glass substrates. X-ray diffraction and scanning electron microscopy showed that these micro-rod arrays had a polycrystalline wurtzite structure and high c-axis preferred orientation. Photoluminescence studies at 10 K show that the increase of manganese content leads to a relative decrease in deep level band intensity with respect to undoped ZnO. Magnetic measurements indicated that undoped ZnO was diamagnetic in nature whereas Mn-doped ZnO samples exhibited ferromagnetic behavior at room temperature, which is possibly related to the substitution of Mn ions (Mn2+) for Zn ions in the ZnO lattice

Role of cavitation, surfactants, and their synergism in transdermal sonophoresis

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemical Engineering, 2011.Cataloged from PDF version of thesis.Includes bibliographical references.The research described in this thesis represents a significant advancement in the current mechanistic understanding of low-frequency ultrasound-mediated transdermal drug delivery. Specifically, while prior research has focused on a more general understanding of the mechanisms associated with low-frequency sonophoresis (LFS), this thesis directly investigates the mechanisms associated with phenomena that occur due to LFS skin treatment. These include a deeper understanding of: i) the reasons for heterogeneous perturbation of skin treated with LFS, ii) the physical mechanism that causes synergism between LFS and chemical penetration enhancers (CPEs), iii) the interactions between traditional and non-traditional surfactants in LFS skin treatments, and iv) the effects of LFS and LFS/CPEs on skin structural perturbation. In the first study of this thesis, the intrinsic properties and formation mechanisms of localized-transport regions (LTRs), and the surrounding less-perturbed non-LTRs, of lowfrequency sonophoresis-treated skin are investigated. By independently analyzing LTR, non- LTR, and total skin samples treated at multiple LFS frequencies, it was found that the pore radii (rpore) within non-LTRs are frequency-independent, ranging from 18.2 - 18.5 A, but significantly larger than rpore of native skin samples (13.6 A). Conversely, rpore within LTRs increases significantly with decreasing frequency from 161 A, to 276 A, and to ao (>300 A) for LFS/SLStreated skin at 60 kHz, 40 kHz, and 20 kHz, respectively. These findings suggest that different mechanisms contribute to skin permeability enhancement within each skin region. Therefore, it was proposed that the enhancement mechanism within LTRs is the frequency-dependent process of cavitation-induced microjet collapse at the skin surface, while the increased rpore values in non-LTRs are likely due to SLS perturbation, with enhanced penetration of SLS into the skin resulting from the frequency-independent process of acoustic streaming. Next, the effects of a non-traditional surfactant on LFS treatment were analyzed through a case study with the commonly used fluorescent dye sulforhodamine B (SRB). SRB is often considered to be a purely hydrophilic molecule, having no impact on bulk or interfacial properties of aqueous solutions. However, it was demonstrated that SRB is in fact an amphiphile, with the ability to adsorb at an air/water interface and to incorporate into sodium lauryl sulfate (SLS) micelles. In fact, SRB reduced the surface tension of water by up to 23 mN/m, and the addition of SRB to an aqueous SLS solution was found to induce a significant decrease in the critical micelle concentration (cmc) of SLS. Molecular dynamics revealed that SRB has defined polar "head" and non-polar "tail" regions when adsorbed at the air/water interface as a monomer. These findings have significant implications into LFS-mediated transdermal drug delivery, as the inclusion of SRB into an LFS coupling solution can cause a synergistic increase in skin permeability enhancement. However, in the presence of SLS, SRB actually causes an antagonistic effect due to the resulting change in bulk and interfacial properties.(cont.) The next investigation of this thesis focused on understanding the synergism between LFS and CPEs (e.g., surfactants). In spite of identifying that the origin of this synergism is the increased penetration and subsequent dispersion of CPEs in the skin in response to LFS treatment, no prior study had proposed a mechanism to explain how LFS induces the observed increased transport of CPEs. In this study, a physical mechanism by which the transport of all CPEs is expected to have significantly increased flux into the localized-transport regions (LTRs) of LFS-treated skin was proposed. Specifically, the collapse of acoustic cavitation microjets within LTRs was shown to induce a convective flux. In addition, because amphiphilic molecules are able to adsorb onto the gas/water interface of cavitation bubbles, amphiphiles were shown to have an additional adsorptive flux. In this sense, the cavitation bubbles were shown to effectively act as carriers for amphiphilic molecules, delivering surfactants directly into the skin when they collapse at the skin surface as cavitation microjets. The flux equations derived for the LTRs and non-LTRs of LFS-treated skin, compared to that for untreated skin, explained how the transport of all CPEs, and to an even greater extent amphiphilic CPEs, increases during LFS treatment. The flux model was supported with experiments involving a non-amphiphilic CPE (propylene glycol) and both nonionic and ionic amphiphilic CPEs (octyl glucoside and SLS), by measuring the flux of each CPE into untreated skin and the LTRs and non-LTRs of LFS-treated skin. Data showed excellent agreement with the expected trends from the flux model. The final study of this thesis investigated the effect of SLS on skin structural perturbation when utilized simultaneously with LFS. Pig full-thickness skin (FTS) and pig split-thickness skin (STS) treated with LFS/SLS and LFS were analyzed in the context of the aqueous porous pathway model to quantify skin perturbation through changes in skin pore radius and porosity-totortuosity ratio (e/t). In addition, skin treatment times required to attain specific levels of skin electrical resistivity were analyzed to draw conclusions about the effect of SLS on reproducibility and predictability of skin perturbation. It was found that LFS/SLS-treated FTS, LFS/SLS-treated STS, and LFS-treated FTS exhibited similar skin perturbation. However, LFStreated STS exhibited significantly higher skin perturbation, suggesting greater structural changes to the less robust STS induced by the purely physical enhancement mechanism of LFS. Evaluation of c/c values revealed that LFS/SLS-treated FTS and STS have similar transport pathways, while LFS-treated FTS and STS have lower cF/ values. In addition, LFS/SLS treatment times were much shorter than LFS treatment times for both FTS and STS. Moreover, the simultaneous use of SLS and LFS not only results in synergistic enhancement, as reflected in the shorter skin treatment times, but also in more predictable and reproducible skin perturbation. In conclusion, the research conducted in this thesis has contributed to the advancement of the molecular and cellular-level understanding of phenomena associated with LFS-mediated transdermal skin permeability enhancement. Additionally, the insights provided by this thesis could lead to the development of optimized LFS treatment protocols and improved LFS coupling solution formulations. This would permit attaining the desired skin permeability using milder LFS treatment conditions and smaller skin treatment areas. This could also lead to lower power requirements of LFS devices, thereby leading to miniaturization of devices and the creation of more commercially-viable LFS equipment.by Baris E. Polat.Ph.D

Effects of ultrasound and sodium lauryl sulfate on the transdermal delivery of hydrophilic permeants: Comparative in vitro studies with full-thickness and split-thickness pig and human skin

The simultaneous application of ultrasound and the surfactant sodium lauryl sulfate (referred to as US/SLS) to skin enhances transdermal drug delivery (TDD) in a synergistic mechanical and chemical manner. Since full-thickness skin (FTS) and split-thickness skin (STS) differ in mechanical strength, US/SLS treatment may have different effects on their transdermal transport pathways. Therefore, we evaluated STS as an alternative to the well-established US/SLS-treated FTS model for TDD studies of hydrophilic permeants. We utilized the aqueous porous pathway model to compare the effects of US/SLS treatment on the skin permeability and the pore radius of pig and human FTS and STS over a range of skin electrical resistivity values. Our findings indicate that the US/SLS-treated pig skin models exhibit similar permeabilities and pore radii, but the human skin models do not. Furthermore, the US/SLS-enhanced delivery of gold nanoparticles and quantum dots (two model hydrophilic macromolecules) is greater through pig STS than through pig FTS, due to the presence of less dermis that acts as an artificial barrier to macromolecules. In spite of greater variability in correlations between STS permeability and resistivity, our findings strongly suggest the use of 700 μm-thick pig STS to investigate the in vitro US/SLS-enhanced delivery of hydrophilic macromolecules.National Institutes of Health (U.S.) (Grant EB-00351)Massachusetts Institute of Technology. Institute for Soldier Nanotechnologies (Grant DAAD-19-02-D-002)National Science Foundation (U.S.). Graduate Research FellowshipConselho Nacional de Pesquisas (Brazil)Fundacao de Amparo a Pesquisa do Estado de Sao Paul

Mask-Associated Dry Eye (MADE) in healthcare professionals working at COVID-19 pandemic clinics

Background: Healthcare professionals working at COVID-19 pandemic clinics have to work with masks during long hours. After the widespread use of masks in the community, many mask-related side effects were reported to clinics. The increase in the number of applicants with dry eye symptoms due to mask use in ophthalmology clinics has led to the emergence of the concept of mask-associated dry eye (MADE). We think that it would be valuable to evaluate ocular surface tests with a comparative study using healthcare professionals working in pandemic clinics, which we think is the right study group to examine the effects of long-term mask use. Aims: We aimed to evaluate the mask-associated dry eye (MADE) symptoms and findings in healthcare professionals who have to work prolonged time with face masks in coronavirus disease 2019 (COVID-19) pandemic clinics. Patients and Methods: In this prospective, observational comparative clinical study, healthcare professionals who use the mask for a long time and work in COVID-19 pandemic clinics were compared with an age and sex-matched control group consisting of short-term masks users, from April 2021 to November 2021. All participants underwent the Ocular Surface Disease Index (OSDI) questionnaire, tear film break-up time (T-BUT), Oxford staining score, Schirmer's test I, and meibography with infrared transillumination. Results: The long-term mask user group consisted of 64 people, while the short-term mask user group consisted of 66 people (260 eyes, total). The OSDI score and Schirmer I measurement were not statistically different between the two groups. T-BUT was statistically significantly shorter in the long-term group (P: 0.008); lid parallel-conjunctival fold, Oxford staining score, and upper and lower lid meibography score were found to be significantly higher in the long-term group (P < 0.001, P: 0.004, P: 0.049, P: 0.044, respectively). Conclusion: Healthcare professionals with longer mask-wearing times are at greater risk of ocular surface damage. It may be considered to prevent this damage by blocking airflow to the ocular surface, such as by wearing a face mask properly or fitting it over the nose with surgical tape. Those who have to work with a mask for a long time during the COVID-19 pandemic should keep in mind the ophthalmology follow-up for eye comfort and ocular surface health