Experimental High-Resolution Observation of the Truncated Double-Icosahedron Structure: A Stable Twinned Shell in Alloyed Au-Ag Core@Shell Nanoparticles.

Given the binary nature of nanoalloy systems, their properties are dependent on their size, shape, structure, composition, and chemical ordering. When energy and entropic factors for shapes and structure variations are considered in nanoparticle growth, the spectra of shapes become so vast that even metastable arrangements have been reported under ambient conditions. Experimental and theoretical variations of multiply twinned particles have been observed, from the Ino and Marks decahedra to polyicosahedra and polydecahedra with comparable energetic stability among them. Herein, we report the experimental production of a stable doubly truncated double-icosahedron structure (TdIh) in Au-Ag nanoparticles, in which a twinned Ag-rich alloyed shell is reconstructed on a Au-Ag alloyed Ino-decahedral core. The structure, chemical composition, and growth pathway are proposed on the basis of high-angle annular dark-field scanning transmission electron microscopy analysis and excess energy calculations, while its structural stability is estimated by large-scale atomic molecular dynamics simulations. This novel nanostructure differs from other structures previously reported.

Production of activated carbon from agave residues and its synergistic application in a hybrid adsorption-AOPs system for effective removal of sulfamethazine from aqueous solutions.

Tequila production in Mexico generates large quantities of agave bagasse (AB), a waste that could be used more efficiently. AB has a high cellulose, hemicellulose, and lignin content, which allows its use as a precursor for synthesizing carbonaceous materials. In the present work, the synthesis of activated carbon impregnated with Fe2+ (AG-Fe-II) and Fe3+ (AG-Fe-III) was carried out and evaluated in a hybrid adsorption-AOP (advanced oxidation process) methodology for sulfamethazine removal (SMT). The materials were characterized before and after the process to determine their morphological, textural, and physicochemical properties. Subsequently, the effect of the main operational variables (pH, initial SMT concentration, mass, and activator dosage) on the hybrid adsorption-degradation process was studied. The Fenton-like reaction was selected as the AOP for the degradation step, and potassium persulfate (K2S2O8) was used as an activating agent. The main iron crystallographic phases in AG-Fe-II were FeS, with a uniform distribution of iron particles over the material's surface. The main crystallographic phase for AG-Fe-III was Fe3O4. The hybrid process achieved 61% and 78% removal efficiency using AG-Fe-II and AG-Fe-III samples, respectively. The pH and initial SMT concentration were the most critical factors for removing SMT from an aqueous phase. Finally, the material was successfully tested in repeated adsorption-degradation cycles.

Application of artificial intelligence for the optimization of advanced oxidation processes to improve the water quality polluted with pharmaceutical compounds.

Sulfamethoxazole and metronidazole are emerging pollutants commonly found in surface water and wastewater. These compounds have a significant environmental impact, being necessary in the design of technologies for their removal. Recently, the advanced oxidation process has been proven successful in the elimination of this kind of compounds. In this sense, the present work discusses the application of UV/H2O2 and ozonation for the degradation of both molecules in single and binary systems. Experimental kinetic data from O3 and UV/H2O2 process were adequately described by a first and second kinetic model, respectively. From the ANOVA analysis, it was determined that the most statistically significant variables were the initial concentration of the drugs (0.03 mmol L-1) and the pH = 8 for UV/H2O2 system, and only the pH (optimal value of 6) was significant for degradation with O3. Results showed that both molecules were eliminated with high degradation efficiencies (88-94% for UV/H2O2 and 79-98% for O3) in short reaction times (around 30-90 min). The modeling was performed using a quadratic regression model through response surface methodology representing adequately 90 % of the experimental data. On the other hand, an artificial neural network was used to evaluate a non-linear multi-variable system, a 98% of fit between the model and experimental data was obtained. The identification of degradation byproducts was performed by high-performance liquid chromatography coupled to a time mass detector. After each process, at least four to five stable byproducts were found in the treated water, reducing the mineralization percentage to 20% for both molecules.

Spiers Memorial Lecture: Nanoalloys of multiple components; the road to advance the field and experimental and theoretical challenges.

The field of nanoalloys has been advancing at a rapid pace in the last two decades. Many new characterization methods and theoretical advances have produced a substantial knowledge of the nanoalloys' properties and structure. Most of the work has been limited to binary alloys. A path forward for the field will be the study of nanoalloys with three or more metals. Adding new components will produce new properties and possibly more fabrication controls. In this paper, we will discuss the challenges that will arise in multi-metallic nanoalloys. We will show that entropy and twin boundaries play a dominant role in multi-metallic alloys.

Two new species of Scotinella Banks, 1911 (Araneae: Phrurolithidae) from Mexico, with a discussion on the female genitalic morphology and intraspecific variation.

The taxonomy of the spider family Phrurolithidae in western Mexico remains poorly investigated. In this work, based on both sexes, we describe Scotinella garman sp. nov. and S. poncei sp. nov. from Michoacn. Specimens of the two new species were collected using pitfall traps in a pine forest, organic avocado orchard, and tropical deciduous forest. The two species seem to be sister species as they resemble each other in several morphological characteristics. Females of Scotinella poncei sp. nov. display a striking variability in the size and depth of the atrium and copulatory openings. Moreover, we discuss the female genitalia conformation of Scotinella, specifically the homology of the secondary spermathecae, and record the genus Phonotimpus Gertsch & Davis, 1940 in western Mexico for the first time.

Evaluation of the Environmental Performance of Adsorbent Materials Prepared from Agave Bagasse for Water Remediation: Solid Waste Management Proposal of the Tequila Industry.

In the present research work, the use of agro-industrial waste such as agave bagasse from the tequila industry was carried out. The agave bagasse was treated to obtain biosorbent and hydrochar materials. Direct Blue 86 was used as an adsorbate model to evaluate the performance of both materials. The adsorption studies showed an adsorption capacity of 6.49 mg g−1 in static and 17.7 mg g−1 in dynamic, associated with a physisorption process between functional groups of the material and the dye. The characterization of the biosorbent showed that the material was mainly composed of macroporous fibers with a surface area <5.0 m2 g−1. Elemental analysis showed a majority composition of C (57.19 wt%) and O (37.49 wt%). FTIR and XPS analyses showed that the material had C-O, C=O, -OH, O-C=O, and -NH2 surface groups. RAMAN and TGA were used to evaluate the composition, being cellulose (40.94%), lignin (20.15%), and hemicellulose (3.35%). Finally, the life-cycle assessment at a laboratory scale showed that the proposed biosorbent presents a 17% reduction in several environmental aspects compared to hydrochar, showing promise as an eco-friendly and highly efficient method for the remediation of water contaminated with dye, as well as being a promising alternative for the responsible management of solid waste generated by the tequila industry.

Male Sexual Health and Reproduction in Cutaneous Immune-Mediated Diseases: A Systematic Review.

INTRODUCTION: Information about the possible effects of cutaneous immune-mediated diseases (cIMDs) on male sexual function and reproduction is scarce. Factors known to impair sexual health and reproduction, such as inflammation, medication use, and hypogonadism, can be present in a significant proportion of male patients with cIMD. OBJECTIVES: To systematically review the literature for the influence of paternal cIMD on many aspects of male sexual and reproductive health, such as sexual function, reproductive hormones, fertility, and pregnancy and offspring outcomes. METHODS: A systematic literature search was performed. The searches combined keywords regarding male sexual function and fertility, pregnancy outcomes, and offspring's health with a list of cIMDs. RESULTS: The majority of the identified studies included patients with psoriasis (22 of 27), and sexual function was the most common outcome of interest (20 of 27). For patients diagnosed with psoriasis, the prevalence of male sexual dysfunction reported in these studies ranged from 34 to 81%. Hypogonadism in patients with psoriasis was reported in 2 of 3 studies. Sperm analysis abnormalities in patients with psoriasis were reported in 3 of 4 studies. No information about the effect of paternal disease on pregnancy and offspring outcomes was identified. CONCLUSIONS: Disease activity in psoriasis might play an important role in the development of sexual dysfunction, hypogonadism, and abnormal sperm quality. For the other cIMD included in this review, there is insufficient information regarding male sexual and reproductive health to draw firm conclusions. More research is needed to understand the association between cIMD and impaired male sexual and reproductive health. Perez-Garcia LF, Dolhain R, te Winkel B, et al. Male Sexual Health and Reproduction in Cutaneous Immune-Mediated Diseases: A Systematic Review. Sex Med Rev 2021;9:423-433.

The Decmon: a new nanoparticle shape along the truncation path from the icosahedron to the decahedron.

The idea that shape and structure determines functionality is one of the leiv-motifs that drives research and applications on fields such as catalysis and plasmonics. The growth and stability of metallic clusters is extensively discussed through faceting and energy minimization mechanisms, respectively. Facet truncations on the regular Mackay-icosahedron (m-Ih) give rise to two sub-families exhibiting five-fold symmetry and external decahedral shape. Such successive truncations made to the regular m-Ih, led to a decahedral motif called 'Decmon' (Montejano's decahedron). This structure expose facets (111) and (100), that after a total energy minimization through molecular dynamics simulations using the embedded atom model, proved to be thermally stable. This result has been confirmed by using nano-thermodynamics. The surface energy competition between the (111) and (100) facets explains its stability at some given cluster sizes, and this truncation path permits to glimpse the potential energy surface in the growth path of nanoparticles from the decahedral (s-Dh) to icosahedral (m-Ih) structures.

Antimycotic Activity Potentiation of Allium sativum Extract and Silver Nanoparticles against Trichophyton rubrum.

A natural and biocompatible extract of garlic as a support, decorated with silver nanoparticles, is a proposal to generate an effective antifungal agent against dermatophytes at low concentrations. Silver nanoparticles (AgNPs) with a diameter of 26±7 nm were synthesized and their antimycotic activity was examined against Trichophyton rubrum (T. rubrum), inhibiting 94 % of growth at a concentration of 0.08 mg ml-1 . Allium sativum (garlic) extract was also obtained (AsExt), and its MIC was 0.04 mg ml-1 . To increase the antifungal capacity of those systems, AsExt was decorated with AgNPs, obtaining AsExt-AgNPs. Using an AsExt concentration of 0.04 mg ml-1 in independent experiments with concentrations from 0.01 to 0.08 mg ml-1 of AgNPs, it was possible to inhibit T. rubrum at all AgNPs concentrations; it proves a synergistic effect between AgNPs and AsExt. Even if 1 % of the minimum inhibitory concentration of AsExt (0.0004 mg ml-1 ) is used, it was possible to inhibit T. rubrum at all concentrations of AgNPs, demonstrating the successful antimycotic activity potentiation when combining AsExt and AgNPs.

The Presence of Alpha-Synuclein in Skin from Melanoma and Patients with Parkinson's Disease.

BACKGROUND: The misfolding and prion-like propagation of the protein α-synuclein (α-syn) is the leading molecular signature in Parkinson's disease (PD). There is a significant coincidence of PD and melanoma that may suggest a shared pathophysiology. This study compared the presence of α-syn in neural crest-derived tissues, such as nevi, melanoma, skin tags, and skin biopsies from patients with PD and healthy controls. METHODS: Biopsies from participants with PD were obtained from patients from a tertiary referral center for dermatology and neurology in Mexico and a private dermatopathology center in Florida between January 2015 and March 2016. Biopsies from 7 patients with melanoma, 15 with nevi, 9 with skin tags, 8 with PD, and 9 skin biopsies from healthy volunteers were analyzed for immunohistochemical determination of α-syn and tyrosinase. All analyses were performed by pathologists who were blinded with respect to the clinical diagnosis. RESULTS: In healthy controls, positive α-syn status was restricted to scattered cells in the basal layer of the epidermis and accounted for 1 ± 0.8% of the analyzed area. In patients with PD, there was increased staining for α-syn PD (3.3 ± 2.3%), with a higher percentage of positive cells in nevi (7.7 ± 5.5%) and melanoma (13.6 ± 3.5%). There was no increased staining in skin tags compared with healthy controls. CONCLUSION: Patients with PD and melanoma have increased staining for α-syn in their skin. The authors propose that neurons and melanocytes, both derived from neuroectodermal cells, may share protein synthesis and regulation pathways that become dysfunctional in PD and melanoma.

Parkinson disease and progressive supranuclear palsy: protein expression in skin.

OBJECTIVE: This study characterizes the expression of tau (p-tau) and α-synuclein (α-syn) by immunohistochemistry in the skin of three different populations: healthy control (HC), Parkinson disease (PD), and progressive supranuclear paralysis (PSP) subjects, with the purpose of finding a biomarker that could differentiate between subjects with PD and PSP. MATERIAL AND METHODS: We evaluated the presence of p-tau and α-syn in a pilot study in the skin of three distinct groups of patients: 17 healthy subjects, 17 patients with PD, and 10 patients with PSP. Four millimeters punch biopsies were obtained from the occipital area and analyzed by immunohistochemistry using antibodies against α-syn and phosphorylated species of tau. PHF (paired helical filaments) antibody identifies p-tau in both normal and pathological conditions and AT8 recognizes p-tau characteristic of pathological conditions. Differences between the three groups were assessed by quantification of immunopositive areas in the epidermis. RESULTS: The immunopositivity pattern of p-tau and α-syn was significantly different among the three groups. Healthy subjects showed minimal staining using AT8 and α-syn. The PD group showed significantly higher α-syn and AT8 immunopositivity, while the PSP group only expressed higher AT8 immunopositivity than HCs. CONCLUSION: These data suggest that the skin reflects brain pathology. Therefore, immunohistochemical analysis of p-tau and α-syn in the skin can be useful for further characterization of PD and PSP.

Electrum, the Gold-Silver Alloy, from the Bulk Scale to the Nanoscale: Synthesis, Properties, and Segregation Rules.

The alloy Au-Ag system is an important noble bimetallic phase, both historically (as "Electrum") and now especially in nanotechnology, as it is applied in catalysis and nanomedicine. To comprehend the structural characteristics and the thermodynamic stability of this alloy, a knowledge of its phase diagram is required that considers explicitly its size and shape (morphology) dependence. However, as the experimental determination remains quite challenging at the nanoscale, theoretical guidance can provide significant advantages. Using a regular solution model within a nanothermodynamic approach to evaluate the size effect on all the parameters (melting temperature, melting enthalpy, and interaction parameters in both phases), the nanophase diagram is predicted. Besides an overall shift downward, there is a "tilting" effect on the solidus-liquidus curves for some particular shapes exposing the (100) and (110) facets (cube, rhombic dodecahedron, and cuboctahedron). The segregation calculation reveals the preferential presence of silver at the surface for all the polyhedral shapes considered, in excellent agreement with the latest transmission electron microscopy observations and energy dispersive spectroscopy analysis. By reviewing the nature of the surface segregated element of different bimetallic nanoalloys, two surface segregation rules, based on the melting temperatures and surface energies, are deduced. Finally, the optical properties of Au-Ag nanoparticles, calculated within the discrete dipole approximation, show the control that can be achieved in the tuning of the local surface plasmon resonance, depending of the alloy content, the chemical ordering, the morphology, the size of the nanoparticle, and the nature of the surrounding environment.

Coalescence and Collisions of Gold Nanoparticles.

We study the assembling of small gold clusters subject to collisions and close contact coalescence by using molecular dynamics simulations to simulate events that occur typically in the sputtering process of synthesis. Our results support the notion that the kinetics of coalescence processes strongly determine the geometry and structure of the final particle. While impact velocities, relative orientations, and the initial shape of the interacting particles are unlikely to strictly determine the structural details of the newly formed particle, we found that high initial temperatures and/or impact velocities increase the probability of appearance of icosahedral-like structures, Wulff polyhedra are likely to be formed as a product of the interactions between nanospheres, while the appearance of fcc particles of approximately cuboctahedral shape is mainly due to the interaction between icosahedra.

Two-stage melting of Au-Pd nanoparticles.

Several series of molecular dynamics runs were performed to simulate the melting transition of bimetallic cuboctahedral nanoparticles of gold-palladium at different relative concentrations to study their structural properties before, in, and after the transition. The simulations were made in the canonical ensemble, each series covering a range of temperatures from 300 to 980 K, using the Rafii-Tabar version of the Sutton and Chen interatomic potential for metallic alloys. We found that the melting transition temperature has a strong dependence on the relative concentrations of the atomic species. We also found that, previous to the melting transition, the outer layer of the nanoparticle gets disordered in what can be thought as a premelting stage, where Au atoms near the surface migrate to the surface and remain there after the particle melts as a whole. The melting of the surface below Tm is consistent with studies of the interaction of a TEM electron beam with Au and Au-Pd nanoparticles.