surface areas
Recently Published Documents





Polymers ◽  
2022 ◽  
Vol 14 (2) ◽  
pp. 340
Marina I. Voronova ◽  
Darya L. Gurina ◽  
Oleg V. Surov

Poly(3-hydroxybutyrate-co-3-hydroxyvalerate)/polycaprolactone (PHBV/PCL) polymer mixtures reinforced by cellulose nanocrystals (CNCs) have been obtained. To improve the CNC compatibility with the hydrophobic PHBV/PCL matrix, the CNC surface was modified by amphiphilic polymers, i.e., polyvinylpyrrolidone (PVP) and polyacrylamide (PAM). The polymer composites were characterized by FTIR, DSC, TG, XRD, microscopy, BET surface area, and tensile testing. The morphological, sorption, thermal, and mechanical properties of the obtained composites have been studied. It was found out that with an increase in the CNC content in the composites, the porosity of the films increased, which was reflected in an increase in their specific surface areas and water sorption. An analysis of the IR spectra confirms that hydrogen bonds can be formed between the CNC hydroxyl- and the –CO– groups of PCL and PHBV. The thermal decomposition of CNC in the PHBV/PCL/CNC composites starts at a much higher temperature than the decomposition of pure CNC. It was revealed that CNCs can either induce crystallization and the polymer crystallite growth or act as a compatibilizer of a mixture of the polymers causing their amorphization. The CNC addition significantly reduces the elongation and strength of the composites, but changes Young’s modulus insignificantly, i.e., the mechanical properties of the composites are retained under conditions of small linear deformations. A molecular-dynamics simulation of several systems, starting from simplest binary (solvent-polymer) and finishing with multi-component (CNC—polymer mixture—solvent) systems, has been made. It is concluded that the surface modification of CNCs with amphiphilic polymers makes it possible to obtain the CNC composites with hydrophobic polymer matrices.

2022 ◽  
Mohammed El Hadi Attia ◽  
Fadl Abdelmonem Essa ◽  
Mohamed Abdelgaied ◽  
Abd elnaby Kabeel

Abstract Numerous studies are being conducted on solar desalination systems with creating new designs to improve the efficiency and yield of these systems. Hemispherical solar still has a relatively large throughput because of its large exposure and evaporation surface areas compared to the other distiller designs. To get the optimal conditions of the parameters that provide the highest productivity of the hemispherical still, three hemispherical basin stills were fabricated and tested. The experiments were performed in three stages: In the first one, the traditional hemispherical solar still THSS (a reference distiller) was compared by THSS with internal reflective mirrors (THSS-IRM). In the second stage, the effect of using different basin metals (THSS with basin metal of zinc (THSS-IRMZ) and basin metal of copper (THSS-IRMC)) with internal reflective mirrors was studied. In the third stage, the two distillers were investigated under using energy storage medium (30 g/L sand grains for each). The THSS with internal reflective mirrors, basin metal of zinc, and energy storage medium is abbreviated by THSS-IRMZSG. Also, THSS with internal reflective mirrors, basin metal of copper, and energy storage medium is abbreviated by THSS-IRMCSG. Moreover, THSS with internal reflective mirrors and energy storage medium is abbreviated by THSS-IRMSG. The results showed that the combination of using internal reflective mirrors, basin material (copper) and energy storage medium provided the best improvement of hemispherical distillation device. The maximum cumulative yield of THSS-IRMCSG was 11.9 L/m².day, while the reference distillation device gave a total yield of 4.65 L/m².day. So, the productivity was improved by around 156%.

Gels ◽  
2022 ◽  
Vol 8 (1) ◽  
pp. 57
Zhongxin Zhang ◽  
Yurui Deng ◽  
Zhiyi Lun ◽  
Xiao Zhang ◽  
Mingyuan Yan ◽  

Polyimide (PI) aerogels were prepared using self-designed silicone polymer cross-linkers with multi-amino from low-cost silane coupling agents to replace conventional small-molecule cross-linkers. The long-chain structure of silicone polymers provides more crosslinking points than small-molecule cross-linkers, thus improving the mechanical properties of polyimide. To investigate the effects of amino content and degree of polymerization on the properties of silicone polymers, the different silicone polymers and their cross-linked PI aerogels were prepared. The obtained PI aerogels exhibit densities as low as 0.106 g/cm3 and specific surface areas as high as 314 m2/g, and the maximum Young’s modulus of aerogel is up to 20.9 MPa when using (T-20) as cross-linkers. The cross-linkers were an alternative to expensive small molecule cross-linkers, which can improve the mechanical properties and reduce the cost of PI aerogels.

Insects ◽  
2022 ◽  
Vol 13 (1) ◽  
pp. 83
Marek Golian ◽  
Tanja Bien ◽  
Sebastian Schmelzle ◽  
Margy Alejandra Esparza-Mora ◽  
Dino Peter McMahon ◽  

Most of our knowledge on insect cuticular hydrocarbons (CHCs) stems from analytical techniques based on gas-chromatography coupled with mass spectrometry (GC-MS). However, this method has its limits under standard conditions, particularly in detecting compounds beyond a chain length of around C40. Here, we compare the CHC chain length range detectable by GC-MS with the range assessed by silver-assisted laser desorption/ionization mass spectrometry (Ag-LDI-MS), a novel and rarely applied technique on insect CHCs, in seven species of the order Blattodea. For all tested species, we unveiled a considerable range of very long-chain CHCs up to C58, which are not detectable by standard GC-MS technology. This indicates that general studies on insect CHCs may frequently miss compounds in this range, and we encourage future studies to implement analytical techniques extending the conventionally accessed chain length range. Furthermore, we incorporate 3D scanned insect body surface areas as an additional factor for the comparative quantification of extracted CHC amounts between our study species. CHC quantity distributions differed considerably when adjusted for body surface areas as opposed to directly assessing extracted CHC amounts, suggesting that a more accurate evaluation of relative CHC quantities can be achieved by taking body surface areas into account.

Antibiotics ◽  
2022 ◽  
Vol 11 (1) ◽  
pp. 91
Sofía C. Santamarina ◽  
Daniel A. Heredia ◽  
Andrés M. Durantini ◽  
Edgardo N. Durantini

The widespread use of antibiotics has led to a considerable increase in the resistance of microorganisms to these agents. Consequently, it is imminent to establish new strategies to combat pathogens. An alternative involves the development of photoactive polymers that represent an interesting strategy to kill microbes and maintain aseptic surfaces. In this sense, a conjugated polymer (PZnTEP) based on Zn(II) 5,10,15,20-tetrakis-[4-(ethynyl)phenyl]porphyrin (ZnTEP) was obtained by the homocoupling reaction of terminal alkyne groups. PZnTEP exhibits a microporous structure with high surface areas allowing better interaction with bacteria. The UV-visible absorption spectra show the Soret and Q bands of PZnTEP red-shifted by about 18 nm compared to those of the monomer. Also, the conjugate presents the two red emission bands, characteristic of porphyrins. This polymer was able to produce singlet molecular oxygen and superoxide radical anion in the presence of NADH. Photocytotoxic activity sensitized by PZnTEP was investigated in bacterial suspensions. No viable Staphylococcus aureus cells were detected using 0.5 µM PZnTEP and 15 min irradiation. Under these conditions, complete photoinactivation of Escherichia coli was observed in the presence of 100 mM KI. Likewise, no survival was detected for E. coli incubated with 1.0 µM PZnTEP after 30 min irradiation. Furthermore, polylactic acid surfaces coated with PZnTEP were able to kill efficiently these bacteria. This surface can be reused for at least three photoinactivation cycles. Therefore, this conjugated photodynamic polymer is an interesting antimicrobial photoactive material for designing and developing self-sterilizing surfaces.

2022 ◽  
Vol 11 (1) ◽  
pp. 46
Adalet Dervisoglu

Deltas and lagoons, which contain many flora and fauna, have rich coastal ecological and biological environments, and are wetlands of vital importance for humans. In this study, the current problems in all coastal Ramsar sites in Turkey are summarized, and changes in water surface areas are investigated using Landsat and Sentinel 1/2 satellite images on the Google Earth Engine (GEE) cloud computing platform. Landsat TM and OLI images were used in the long-term analysis, and time series were created by taking annual and July to September averages between 1985 and 2020. In the short-term analysis, monthly averages were determined using Sentinel 2 images between 2016 and 2020. Sentinel-1 Synthetic Aperture Radar (SAR) images were used in the months when optical data were not suitable for use in monthly analysis. The Normalized Difference Water Index (NDWI) was used to extract water surface areas from the optical images. Afterwards, a thresholding process was used for both optical and radar images to determine the changes. The changes were analyzed together with the meteorological data and the information obtained from the management plans and related studies in the literature. Changes in the water surface areas of all coastal Ramsar sites in Turkey were determined from 1985 to 2020 at different rates. There was a decreasing trend in the Goksu and Kızılırmak Deltas, which also have inland wetlands. The decreasing rates from 1985 to 2020 were −24.52% and −2.86%, for annual average water surfaces for the Goksu and Kızılırmak Deltas, respectively, and −21.64% and −6.34% for the dry season averages, respectively. However, Akyatan Lagoon, which also has inland wetlands, showed an increasing trend. Observing the annual average surface area from 1985 to 2020, an increase of 438 ha was seen, corresponding to 7.65%. Every year, there was an increasing trend in the Gediz Delta and Yumurtalık Lagoons, that do not have inland wetlands. The increasing rates from 1985 to 2020 were 46.01% and 17.31% for the annual average surface area, for the Gediz Delta and Yumurtalık Lagoons, respectively, and 38.34% and 21.04% for the dry season average, respectively. The obtained results reveal the importance of using remote sensing methods in formulating strategies for the sustainable management of wetlands.

2022 ◽  
Alexson Filgueiras Dutra ◽  
Rafael Fausto de Lima ◽  
Francisco de Alcântara Neto ◽  
Guilherme Botega Torsoni ◽  

Abstract BACKGROUND:The presente paper aims to compute climatological zones apt for the cultivation of pitaya based on trends in the occurrence of climate change events from the IPCC in Brazil. We used temperature and precipitation data from 4,942 cities collected on the NASA / POWER platform from 1990 to 2020 to elaborate on the current scenario. The climate change scenarios were obtained using the CHELSA platform (Climatologies at high resolution for the earth's land surface areas) and corresponded to the periods 2041-2060 and 2061-2080 associated with four IPCC climate change scenarios. The spatialization and interpolation of data occurred according to the aptitude classes designed to meet the thermal and water needs of the crop. RESULTS: Forecasts of increase in temperature indices and reduction in accumulated rainfall were found in all Brazil, but with greater impact in the North and Northeast regions, which had the greatest reduction in areas at low risk for the cultivation of pitaya. In the South and Southeast regions, a large part of the areas remained suitable for the production of this fruit until 2080. CONCLUSION:The results suggest that climate change does not benefit the cultivation of pitaya in some regions of Brazil because the dimensions of the areas apt for economic production be restricted.

2022 ◽  
Vol 5 (1) ◽  
pp. 90
Maria Kouroutzi ◽  
Antonios Stratidakis ◽  
Marianthi Kermenidou ◽  
Spyros Karakitsios ◽  
Dimosthenis Sarigiannis

A novel roofing tile was developed containing various types of nanoparticles of titanium dioxide (TiO2). Experiments were conducted using three types of TiO2 nanoparticles with and without polyethylene glycol (PEG). All types of newly developed nanomaterials were characterized using X-ray diffractometry. Particle size distribution analysis was performed and specific surface area was determined using the Brunauer–Emmet–Teller method. SEM imaging was used for the morphological characterization of nanoparticles. Commercial ceramic roofing tiles underwent a dip-coating procedure to obtain the desired photocatalytic surface. The TiO2 anatase samples exhibited greater surface areas of nanoparticles, thus providing potentially the highest photocatalytic efficiency.

2022 ◽  
Hefeng Sun ◽  
Pengfei Sun ◽  
Haiyue Jiang ◽  
Qinghua Yang ◽  
Tongtong Li ◽  

Abstract The tissue expansion technique is the most suitable procedure for Chinese patients with microtia. However, it is difficult to determine whether the expanded flap is sufficient, and there are no clear or objective guidelines for determining the volume of the expander for different sizes of auricles. One hundred patients with unilateral microtia who visited our department in 2021 were randomly selected for auricular data collection using 3D scanning. The auricle length, width, projection, perimeter, and surface area were measured. Eight different volumes of expanders underwent CT and the surface areas of these expanders were measured. The surface areas of the auricles and expanders were compared and the correlation between them was explored. The average auricle parameters were calculated. The scatter plot showed a linear relationship between auricle length and auricle surface area (R2 = 0.9913), which demonstrated that the auricle area was approximately equal to the auricle length multiplied by 76.921. Additionally, the surface area of the expanders was measured and made into a table for selection against the surface area of the auricles. Using our equation, the auricle surface could be estimated by simply measuring the non-defective auricle length; therefore, the suitable volume of the expander could be determined.

2022 ◽  
zhikai hong ◽  
yingjiao dong ◽  
ruijie wang ◽  
Guanhua Wang

Covalent organic framework materials (COFs), a kind of porous organic material, have excellent potential application in the field of sample pretreatment due to their high surface areas and thermal stability....

Sign in / Sign up

Export Citation Format

Share Document