Interconnected Capillary Channels Research Articles

Development of xanthan gum-based solid desiccants for the extraction of water vapors from humid air

A xanthan gum-acrylamide desiccant with interconnected capillary channels was prepared and showed 1.38 g g−1 water adsorption at 90% RH and 25 °C, retaining 70% capacity over 20 cycles, proving its effectiveness as a salt-free desiccant.

Highly porous double network hydrogel having fast responding time and high mechanical strength via emulsion template polymerization

AbstractPorous polymer hydrogels with high mechanical properties and response time is such a unique coalition that may open up many new application avenues especially in biomaterials, nevertheless which is a challenging task to achieve. This work highlighted a novel yet simple approach on developing highly porous, fast swelling hydrogels having high mechanical performance by slightly twisting the traditional double network concept following emulsion template polymerization. The fabricated acrylamide hydrogel structure entails 40–70 micrometer size pores while having ultimate compressive strength of 5–7 MPa. Further, it exhibited approximately 400 wt% water absorptivity compared to the dry weight of the sample in 15 s at 30°C. Such enhanced swelling properties of the developed hydrogel are due to the surface roughness of interconnected capillary channels.

Capturing water vapors from atmospheric air using superporous gels

Dehumidification performance of most polymer desiccant materials is unsatisfactory because of the complex adsorption mechanism on polymer surface and non-porous structure. A viable alternative of solid desiccants, especially existing polymer desiccants, for capturing water vapors from moist air is the super-porous gels (SPGs). The presence of interconnected channels of pores in its structure facilitates the transfer of water molecules to the internal structure of SPGs. Therefore, in this research work, we are proposing N-isopropylacrylamide (NIPAM) and acrylamide (AM) based thermoresponsive SPGs as a potential alternative to the existing conventional solid desiccants. To ensure the formation of interconnected capillary channels, the SPGs were synthesized via gas blowing and foaming technique. Surface morphology of the SPGs was studied using scanning electron microscopy (SEM) and the other physio-chemical characteristics were studied using different techniques like fourier Transform Infrared Spectroscopy (FTIR), X-ray diffraction (XRD) and thermo-gravimetric analysis (TGA). Water vapors adsorption properties of the SPGs were explored via adsorption isotherm and kinetics. The adsorption isotherm was found to be of type-III isotherm with a maximum adsorption capacity of 0.75 gw/gads at 25 °C and 90% relative humidity. Experimental isotherm data correlated well with BET, FHH and GAB isotherm models. Adsorption kinetics suggested that the water vapors diffusion followed intraparticle diffusion and liquid field driving mechanisms collectively. SPGs exhibited very good regeneration and reusability for ten continuous adsorption/desorption cycles. Therefore, the dehumidification efficiency of synthesized SPGs shows that they have potential to replace most of the conventional solid desiccant materials in use.

Bio-inspired Microfluidic Devices for Passive, Directional Liquid Transport: Model-based Adaption for Different Materials

The Texas Horned lizard has the ability to harvest moisture from ambience with its skin and to transport water directionally to its snout; at the same time water is hindered to flow in opposite direction. We present a passive microfluidic device for directional liquid transport which is inspired by this natural role model. To this end, we deduce a subnatural capillary network from the measurement data of the Texas Horned lizard's skin. We adapt the network to various liquid-polymer combinations with the help of a mathematical model. Applying a CO2 laser we engrave the structures into poly(methyl methacrylate) (PMMA). By distance measurements we verify that our devices transport liquids of different contact angles in a preferential direction, while stopping it in opposite direction. The applied network of interconnected capillary channels is advantageous, when it comes to defects during production or when particles block part of the capillary channels. The proposed concept is thought to be useful for micro-analysis devices and lubrication.

Topical vaginal drug delivery system based on superporous hydrogel hybrids.

In this investigation a novel approach based on mucoadhesive superporous hydrogel hybrids (SPHHs) for topi- cal vaginal drug delivery for Metronidazole was tried. SPHHs were synthesized by solution polymerization tech- nique. The synthesized SPHHs were characterized for tensile strength, swelling behavior, porosity, density, mucoadhesion time, SEM, DSC and FT-IR studies. In vitro drug release study from prepared vaginal formulation based on SPHH was performed in simulated vaginal fluid. Different mathematical models were applied to ascertain the drug release mecha- nism. SPHHs have shown good tensile strength, mucoadhesion time and drug release for 24 hour. SEM images reflected the formation of pores and interconnected capillary channels. The release kinetic of drug from the prepared system was best explained by Korsmeyer-Peppas and Higuchi models and shown anomalous transport. The proposed novel drug de- livery system based on SPHH was successfully prepared and SPHH-DDS might be promising candidate for topical vagi- nal delivery of Metronidazole.

Angiolipoma of the Female Breast: Clinicomorphological Correlation of 52 Cases

The authors analyzed 52 cases of female breast angiolipoma (AL). Age distribution was 25 to 80 years of age (56.81 ± 12.78). Most cases showed vascularity below 50%, and 14 cases had vascularity >50%. Cellular and low-vascularity ALs had different clinical and radiological presentations. The mean size was 7.00 ± 3.62 mm for cellular ALs and 19.61 ± 7.58 mm for low-vascularity ALs. In any paucicellular area, the authors could identify a cluster of at least 3 interconnected vessels. The endothelium was mostly flat with uniform, hyperchromatic nuclei, and mitoses and nucleoli were absent. Fibrin thrombi in proliferating capillaries were noted in 96% of cases. Low-vascularity AL can be reliably distinguished on needle core biopsy from other lipomatous and vascular tumors of the breast. Tortuosity and proliferation of capillaries with at least 3 interconnected capillary channels in 1 focus with associated fibrin thrombi constitute a very strong clue for the diagnosis of AL on a breast needle core biopsy. Definite diagnosis of cellular AL is not always feasible because of rare cases with mitotic activity and cellular atypia. Excision is often recommended for cellular AL.

Leukocyte Margination in Alveolar Capillaries: Interrelationship with Functional Capillary Geometry and Microhemodynamics

The pulmonary capillary microvasculature harbors a large pool of intravascularly marginated leukocytes. In this study, we investigated the interrelationship of leukocyte margination with characteristics of functional capillary geometry and microhemodynamics in alveolar capillary networks. In 22 anesthetized rabbits we assessed functional capillary density, average capillary length, red blood cell velocity and leukocyte kinetics in alveolar capillary networks in vivo by intravital fluorescence microscopy. In alveolar wall areas of 12,800 ± 1,800 μm², we detected 3.6 ± 0.5 sticking leukocytes and 21.0 ± 1.9 functional capillary segments with an average capillary length of 35.7 ± 2.1 μm. We calculated that approximately 15% of functional capillary segments are blocked by marginated leukocytes. Leukocyte margination was predominantly observed in capillary networks characterized by a high functional capillary density, short capillary segments and low red blood cell velocities. The multitude of interconnected capillary channels in these networks may allow alveolar blood flow to bypass marginated leukocytes. Hence, this interrelationship may be relevant for maintenance of adequate alveolar perfusion and low capillary network resistance despite excessive leukocyte margination in the pulmonary microvasculature. Local microhemodynamic factors may play a regulatory role in the spatial distribution of leukocyte margination.