Effects of Carbon Templates in Tetraethyl Orthosilicate-Derived Superhydrophobic Coatings.

Superhydrophobic coatings have garnered significant research interest due to their potential applications in areas such as ant-icing and windows. This study focuses on the development of superhydrophobic coatings using air-assisted electrospray and the effect of different carbon additives as templates in the coating. Carbon templates, with their unique topological varieties, offer a cost-effective alternative to other patterning technologies such as photolithography. By introducing dispersed carbon black, carbon nanotubes, and graphene additives in TEOS solution, silica is given the ability of localized secondary growth on or around the carbon surfaces as well as the building structure to provide adequate roughness on the substrate surface. The templated silica formations provide a thin coating with nano-scale roughness for heightened water resistance. As compared with the template-free coating that has small silica particles, a surface roughness of 135 nm, and a water contact angle (WCA) of 101.6° (non-superhydrophobic), the carbon templating effect allowed for increased silica particle size, a surface roughness as high as 845 nm, a WCA above 160°, and the ability to maintain superhydrophobicity over 30 abrasion cycles. The morphological characteristics that resulted from the templating effect correlate directly with heightened performance of the coatings. Herein, the carbon additives have been found to serve as cheap and effective templates for silica formation in thin TEOS-derived superhydrophobic coatings.

Achieving Superhydrophobic Surfaces via Air-Assisted Electrospray.

Superhydrophobic surface is an enabling technology in numerous emerging and practical applications such as self-cleaning, anticorrosion, antifouling, anti-icing coatings, and oil-water separation. Here, we report a facile air-assisted electrospray approach to achieve a superhydrophobic surface by systematically studying spray conditions and the chemistry of a coating precursor solution consisting of silicon dioxide nanoparticles, polyacrylonitrile, and N,N-dimethylformamide. The wettability behavior of the surface was analyzed with contact angle measurement and correlated with surface structures. The superhydrophobic coating exhibits remarkable water and oil repellent characteristics, as well as good robustness against abrasion and harsh chemical conditions. This air-assisted electrospray technique has shown great control over the coating process and properties and thus can be potentially used for various advanced industrial applications for self-cleaning and anticorrosion surfaces.

A Mini Review on Superhydrophobic and Transparent Surfaces.

In recent years, self-cleaning and transparent surfaces have been widely studied for application on smart windows, solar panels, camera lenses, and other optoelectronic devices. The self-cleaning properties can possibly extend the lifetime of these products and decrease, even eliminate, the requirement of chemical detergents and high labor costs of cleaning. It can also promote the overall efficiency of outdoor optoelectronic devices (e. g. solar cell panels) since dirt accumulation and bacteria growth can be slowed down, even inhibited on such surfaces. In this mini review, the fundamentals and conditions that govern superhydrophobicity and transparency are introduced, followed by the discussion of roughness as the competing factor for superhydrophobicity and transparency. Representative examples of the surface design and fabrication are introduced and future perspectives are shared. This mini review can help the research community better understand such surfaces and further accelerate its development for innovative practical applications.

Metal Doping Regulates Electrocatalysts Restructuring During Oxygen Evolution Reaction.

High-efficiency and low-cost catalysts for oxygen evolution reaction (OER) are critical for electrochemical water splitting to generate hydrogen, which is a clean fuel for sustainable energy conversion and storage. Among the emerging OER catalysts, transition metal dichalcogenides have exhibited superior activity compared to commercial standards such as RuO2, but inferior stability due to uncontrolled restructuring with OER. In this study, we create bimetallic sulfide catalysts by adapting the atomic ratio of Ni and Co in CoxNi1-xSy electrocatalysts to investigate the intricate restructuring processes. Surface-sensitive X-ray photoelectron spectroscopy and bulk-sensitive X-ray absorption spectroscopy confirmed the favorable restructuring of transition metal sulfide material following OER processes. Our results indicate that a small amount of Ni substitution can reshape the Co local electronic structure, which regulates the restructuring process to optimize the balance between OER activity and stability. This work represents a significant advancement in the development of efficient and noble metal-free OER electrocatalysts through a doping-regulated restructuring approach.

Investigating the Effects of Lithium Phosphorous Oxynitride Coating on Blended Solid Polymer Electrolytes.

Solid-state electrolytes are very promising to enhance the safety of lithium-ion batteries. Two classes of solid electrolytes, polymer and ceramic, can be combined to yield a hybrid electrolyte that can synergistically combine the properties of both materials. Chemical stability, thermal stability, and high mechanical modulus of ceramic electrolytes against dendrite penetration can be combined with the flexibility and ease of processing of polymer electrolytes. By coating a polymer electrolyte with a ceramic electrolyte, the stability of the solid electrolyte is expected to improve against lithium metal, and the ionic conductivity could remain close to the value of the original polymer electrolyte, as long as an appropriate thickness of the ceramic electrolyte is applied. Here, we report a bilayered lithium-ion conducting hybrid solid electrolyte consisting of a blended polymer electrolyte (BPE) coated with a thin layer of the inorganic solid electrolyte lithium phosphorous oxynitride (LiPON). The hybrid system was thoroughly studied. First, we investigated the influence of the polymer chain length and lithium salt ratio on the ionic conductivity of the BPE based on poly(ethylene oxide) (PEO) and poly(propylene carbonate) (PPC) with the salt lithium bis(trifluoromethanesulfonyl)imide (LiTFSI). The optimized BPE consisted of 100 k molecular weight PEO, 50 k molecular weight PPC, and 25(w/w)% LiTFSI, (denoted as PEO100PPC50LiTFSI25), which exhibited an ionic conductivity of 2.11 × 10-5 S/cm, and the ionic conductivity showed no thermal memory effects as the PEO crystallites were well disrupted by PPC and LiTFSI. Second, the effects of LiPON coating on the BPE were evaluated as a function of thickness down to 20 nm. The resulting bilayer structure showed an increase in the voltage window from 5.2 to 5.5 V (vs Li/Li+) and thermal activation energies that approached the activation energy of the BPE when thinner LiPON layers were used, resulting in similar ionic conductivities for 30 nm LiPON coatings on PEO100PPC50LiTFSI25. Coating BPEs with a thin layer of LiPON is shown to be an effective strategy to improve the long-term stability against lithium.

Fine grade engineered microcrystalline cellulose excipients for direct compaction: Assessing suitability of different dry coating processes.

Recent work showed that contrary to conventional wisdom, fine surface engineered excipients outperform their larger counterparts in blends of highly loaded blends of cohesive drug powders in terms of their packing, flowability and tablet tensile strength. Here, two continuous devices, fluid-energy mill (FEM) and conical mill (Comil), are compared with LabRAM, a batch device used in previous work, for nano-silica dry coating of microcrystalline cellulose (MCC) excipients, 20 and 30 µm. Coated MCCs from all three devices had higher bulk densities and flow function coefficients (FFCs) compared with Avicel PH-102. Silica coating quality was best with LabRAM, but also good with FEM and Comil, although Comil was less effective for the finer MCC. However, the better coating quality of LabRAM had a downside of having poorer compaction properties. The most surprising outcome was that multi-component blends of 17 wt% coated MCC with 60 wt % Ibuprofen 50 had higher bulk density, higher or similar flowability, higher tablet tensile strength, and comparable Ibuprofen dissolution from tablets, compared to those with Prosolv 50, a silicified excipient. The FEM dry coated MCC blends, having only 0.17 wt% silica, performed the best, having desirable bulk density, FFC, and tensile strength that could facilitate high-speed direct compression tableting. In summary, considering that achieving best coating quality need not be the primary objective, FEM may be the best option for producing desired sized dry coated fine excipients.

Single Cobalt Sites Dispersed in Hierarchically Porous Nanofiber Networks for Durable and High-Power PGM-Free Cathodes in Fuel Cells.

Increasing catalytic activity and durability of atomically dispersed metal-nitrogen-carbon (M-N-C) catalysts for the oxygen reduction reaction (ORR) cathode in proton-exchange-membrane fuel cells remains a grand challenge. Here, a high-power and durable Co-N-C nanofiber catalyst synthesized through electrospinning cobalt-doped zeolitic imidazolate frameworks into selected polyacrylonitrile and poly(vinylpyrrolidone) polymers is reported. The distinct porous fibrous morphology and hierarchical structures play a vital role in boosting electrode performance by exposing more accessible active sites, providing facile electron conductivity, and facilitating the mass transport of reactant. The enhanced intrinsic activity is attributed to the extra graphitic N dopants surrounding the CoN4 moieties. The highly graphitized carbon matrix in the catalyst is beneficial for enhancing the carbon corrosion resistance, thereby promoting catalyst stability. The unique nanoscale X-ray computed tomography verifies the well-distributed ionomer coverage throughout the fibrous carbon network in the catalyst. The membrane electrode assembly achieves a power density of 0.40 W cm-2 in a practical H2 /air cell (1.0 bar) and demonstrates significantly enhanced durability under accelerated stability tests. The combination of the intrinsic activity and stability of single Co sites, along with unique catalyst architecture, provide new insight into designing efficient PGM-free electrodes with improved performance and durability.

Surface engineered excipients: III. Facilitating direct compaction tableting of binary blends containing fine cohesive poorly-compactable APIs.

Direct compaction tableting, a desired manufacturing option, is infeasible for blends containing fine cohesive poorly-compactable APIs at higher drug loadings. In this study, the feasibility of using fine, dry coated excipients is investigated instead of dry coating of the APIs, as was done previously. Avicel PH-105 (20.1 µm) dry coated with 1 wt% hydrophilic silica A200 as an engineered excipient was blended with fine (11.3 µm) or semi-fine (30.2 µm) Acetaminophen, or Ibuprofen 50 (55.4 µm) in binary blends at low, medium and high drug loadings (10%, 30%, 60%). The blend uniformity, bulk density, flowability, as well as tablet properties such as friability, weight variation and strength demonstrate overall better performance compared to blends with Avicel PH-105, Prosolv 50 or Prosolv 90 as the excipient. These results along with processability maps of bulk density vs. FFC and tablet tensile strength vs. FFC indicate dry coated Avicel PH-105 could enable direct compaction for IBU50 and cAPAP at all drug loadings, and up to 30% drug loading for mAPAP. In contrast, Prosolv 90 failed for IBU50 at 60% drug loading, and for mAPAP at all drug loadings. Prosolv 50 could only enable direct compaction for IBU50 at all drug loadings. These unexpected outcomes suggest that for direct compaction of very fine, cohesive APIs at higher drug loadings, surface modified fine excipients perform better. A surprising outcome is the improvement in tablet strength for blends with dry coated Avicel PH-105 compared to uncoated Avicel PH-105 at higher drug loading, especially considering parts I and II showed that silica dry coating decreases the placebo tablet tensile strength.

Congenital Cystic Adenomatoid Malformation Volume Ratio in Prenatal Assessment of Prognosis of Fetal Pulmonary Sequestrations.

This study aimed to evaluate the prognosis of pulmonary sequestration (PS) by measuring congenital cystic adenomatoid malformation volume ratio (CVR) value in fetal congenital PS. The fetal CVR in 49 cases of fetal PS diagnosed by prenatal ultrasound in Xiangyang No. 1 People's Hospital from March 2010 to June 2017 were measured, and the clinical outcomes were observed. According to the prenatal ultrasound CVR value, 49 fetuses diagnosed with PS were divided into 2 groups: group 1 with CVR≥1.26, and group 2 with CVR<1.26. The incidence rate of fetal edema, respiratory distress symptoms and survival rate were compared between the two groups. The risk factors of the fetal PS were evaluated by single and multiple Logistic regression analysis. The correlation between CVR and fetal prognosis was analyzed. Of the 49 fetuses, there were 34 cases of PS (ILS) type (69.39%, 34/49), 10 cases of PS (ELS) type I (20.41%, 10/49) and 5 cases of PS (ELS) type II (10.20%, 5/49). Forty-six cases (93.88%, 46/49) were born alive, there was 1 case (CVR ≥1.26) (2.04%, 1/49) of induced abortion, and 2 cases (CVR ≥1.26) (4.08%, 2/49) of stillbirths. In group 1 (n=24), 21 cases were born alive, and the incidence rate of newborn respiratory distress and fetal edema was 100% (21/21) and 79.17% (19/24) respectively. In group 2 (n=25), there were 3 cases (12%,3/25) of newborn respiratory distress, 3 cases (12%, 3/25) of fetal edema, and the rate of live birth was 100%. There were statistically significant differences between the two groups in the incidence of fetal edema, postpartum respiratory symptoms and survival rate. CVR was a risk factor for PS and was associated with fetal prognosis. CVR in the midtrimester of pregnancy is an effective index to evaluate the prognosis of fetal PS. CVR ≥1.26 is associated with an increased risk of fetal edema, infant respiratory distress and intrauterine or postnatal death.

Surface engineered excipients: I. improved functional properties of fine grade microcrystalline cellulose.

Excipients with good flowability, bulk density as well as compaction properties are desired for use in tableting since they play important roles in formulation development and processing, including, handling, mixing, feeding and compaction. The objective of this paper is to examine the feasibility of using dry coating based surface modification of microcrystalline cellulose, Avicel PH-105, to produce an engineered fine grade (<30 µm) excipient that has all three desired properties. Using a material sparing high-intensity vibrational mixer, Avciel PH-105 is dry coated with 1 wt% Aerosil 200, selected due to its relatively higher dispersive surface energy and lower particle size amongst other silica choices. The results indicated that as expected, the bulk density and flowability are significantly improved, while there was an appreciable loss of compaction. To minimize the loss of compaction, attributed to decreased surface energy after coating, while maintaining improved bulk density and flowability, the effect of reduced silica amount was examined. Remarkably, at reduced levels (0.5 wt% to 0.7 wt%) of Aerosil 200, significant improvements in bulk density and flowability were attained with only 9%-12% compaction reduction. The properties of the surface-engineered excipients were compared with several other commercially available pharmaceutical excipients using two different processibility or regime maps; tablet tensile strength versus bulk density or flow function coefficient (FFC). The surface engineered excipients exhibited the best overall performance establishing a promising pathway to engineer excipients using dry processing instead of complex processes such as spray drying.

Surface engineered excipients: II. Simultaneous milling and dry coating for preparation of fine-grade microcrystalline cellulose with enhanced properties.

A solventless process for simultaneously milling and dry coating microcrystalline cellulose (MCC) was investigated for producing fine excipients in five different sizes (∼20, 25, 30, 35, 40 µm) having high bulk density (BD), good flow function coefficient (FFC), and excellent compaction. Avicel PH-102, used as the starting material, was milled and coated with two grades of silicas, hydrophobic and hydrophilic (R972P and A200), using a fluid energy mill (FEM). Through judicious selection of the FEM feed rate, feeding pressure, and grinding pressure, five desired milled sizes were produced. The bulk density of all the milled-coated (1 wt% A200) excipients was significantly better than uncoated-milled MCC, Avicel PH-102, and Prosolv 50 and 90. Whereas the FFC values were greater than uncoated-milled MCC, Avicel PH-102, and Prosolv 50 (latter for ∼30, 35, and 40 µm sizes). The tablet compaction testing was used to evaluate compactibility (tensile strength vs tablet porosity), compressibility (tablet porosity vs compaction pressure), and tabletibility (tensile strength vs compaction pressure). The results indicate that all finer grade milled and A200 coated MCC had lower porosity and higher tablet strengths than Prosolv 50 and 90 at all compaction pressures. Surprisingly, the BD and FFC were better for A200 than for R972P coated-milled MCCs; explained through analyzing inter-particle contact models. Finally, milling did not increase the moisture content but coating with silica led to a slight increase; A200 higher than R972P. It is hoped that these engineered excipients would help formulators with a multitude of options for finer excipients without loss of flow and bulk density.