Thermoelectric Characteristics of Flexible Reduced Graphene Oxide/Silver Selenide Nanowire Composites Prepared by a Facile Vacuum Filtration Process

The reduced graphene oxide/silver selenide nanowire (rGO/Ag2Se NW) composite powders were fabricated via a wet chemical approach, and then flexible rGO/Ag2Se NW composite film was prepared by a facile vacuum filtration method combined with cold-pressing treatment. A highest power factor of 228.88 μWm-1K-2 was achieved at 340 K for the cold-pressed rGO/Ag2Se NW composite film with 0.01 wt% rGO. The rGO/Ag2Se NW composite film revealed superior flexibility as the power factor retained 94.62% after bending for 500 times at a bending radius of 4 mm, which might be due to the interwoven network structures of Ag2Se NWs and pliability of rGO as well as nylon membrane. These results demonstrated the GO/Ag2Se NW composite film has a potential for preparation of flexible thermoelectric devices.

Lime/Sodium Carbonate Treated Seawater to Improve Flocculation and Sedimentation of Clay-Based Tailings

Seawater treated with lime and sodium carbonate in different proportions to reduce magnesium and calcium contents is used in flocculation and sedimentation tests of artificial quartz and kaolin tailings. Solid complexes were separated from water by vacuum filtration, and factors such as lime/sodium carbonate ratio, kaolin content, flocculation time, and flocculant dose are evaluated. The growth of the aggregates was captured in situ by a focused beam reflectance measurement (FBRM) probe. Solid magnesium and calcium complexes are formed in raw seawater at pH 11, impairing the performance of flocculant polymers based on polyacrylamides. The results show that the settling rate improved when the treatment’s lime/sodium carbonate ratio increased. That is, when a greater removal of magnesium is prioritized over calcium. The amount of magnesium required to be removed depends on the mineralogy of the system: more clay will require more significant removal of magnesium. These results respond to the structural changes of the flocs, achieving that the more magnesium is removed, the greater the size and density of the aggregates. In contrast, calcium removal does not significantly influence flocculant performance. The study suggests the necessary conditions for each type of tailing to maximize water recovery, contributing to the effective closure of the water cycle in processes that use seawater with magnesium control.

High-Performanced Hemicellulose Based Organic-Inorganic Films with Polyethyleneimine

For the high-value utilization of hemicellulose-based composite films, the poor film-forming and mechanical properties of hemicellulose-based composite films must be surmounted crucially. Based on this, hemicellulose-based organic-inorganic composite films with good mechanical properties were prepared from quaternized hemicelluloses (QH), bentonite, and polyethyleneimine (PEI). The QH/PEI/bentonite composite films were prepared by vacuum filtration, and the properties of the composite film were investigated. The results showed that the QH was inserted into bentonite nanosheets through hydrogen bonding and electrostatic interactions. PEI was cross-linked with hemicellulose by hydroxyl groups, electrostatically attracted by the bentonite flake layers. The mechanical properties of the composite films were significantly increased by the incorporation of PEI. When the PEI content was 20%, the tensile stress of the composite film was increased by 155.18%, and the maximum tensile stress was reached 80.52 MPa. The composite films had strong UV absorption ability with the transmittance was almost 0 in the UV region from 200 to 300 nm. The thermal property of composite film was also improved, and the residual mass increased by three times compared to QH. These results provide a theoretical basis for the use of hemicellulose-based composite films in packaging applications.

Flexible Tellurium-Based Electrode for High-Performance Lithium-Tellurium Battery

Low-dimensional nanomaterials have attracted considerable attention for next-generation flexible energy devices owing to their excellent electrochemical properties and superior flexibility. Herein, uniform Tellurium nanotubes (Te NTs) were prepared through a facile hydrothermal method, and then a flexible and freestanding electrode was fabricated with Te NTs as active materials and a small amount of nanofibrillated celluloses (NFCs) as a flexible matrix through a vacuum filtration method without adding extra conductive carbon or a binder. The resulting Te-based electrode exhibits a high volumetric capacity of 1512 mAh cm−3 at 200 mA g−1, and delivers admirable cyclic stability (capacity retention of 104% over 300 cycles) and excellent rate performance (833 mAh cm−3 at 1000 mA g−1), which benefits from the unique structure and intrinsically superior conductivity of Te NTs. After bending 50 times, the Te-based electrode delivers a desirable volumetric capacity of 1117 mAh cm−3, and remains 93% of initial capacity after 100 cycles. The results imply that the Te-based electrode exhibits excellent electrochemical properties and superior flexibility simultaneously, which can serve as a potential candidate for the flexible lithium batteries.

A New Approach for Determining Compressibility and Permeability Characteristics of Dredged Slurries with High Water Content

In the vacuum treatment of dredged slurries via prefabricated vertical drains (PVDs), both filtration and consolidation may happen to them when subjected to the vacuum gradient. Similar to the consolidation, the filtration may provide equally useful information on interpreting the constitutive behavior of the slurry. In this paper, a new approach utilizing the filtration process is devised to evaluate the constitutive behaviors of dredged slurries. The approach is composed of a vacuum filtration device and an iterative curve fitting algorithm. Two types of tests, namely step-vacuum filtration and constant-vacuum filtration followed by compression test, must be conducted on the slurry specimens, and only the time variations of the filtrate discharge should be recorded. On the basis of the recorded data, the curve fitting algorithm is adopted for determining the parameters of the constitutive equations. The effectiveness of the proposed approach is verified through comparing the obtained compressibility and permeability of the slurries with the data provided by the oedometer test and with the empirical relationships from different sources. The comparisons demonstrate that the constitutive relationships determined by the present approach can predict the compressibility and permeability characteristics of dredged slurries with an acceptable degree of accuracy.

Determining the Efficiency and Yield of Caffeine Extraction for Robusta and Arabica Coffee Beans

The objective of this review is to determine the difference in caffeine content in the coffee beans from different brands that are available in Costco. Two different popular coffee bean brands were bought and tested to determine which brand would have the highest caffeine content and their relative popularity among consumers. The extraction DMC method was conducted by using chemicals such as calcium carbonate, water, and DMC. The same amount of coffee beans were boiled with water until highly concentrated solutions were formed. Extraction funnel was utilized to wash out caffeine. Then, the recrystallization and vacuum filtration was utilized to obtain caffeine in solid form. The identity of the product along with the purity of the product was determined using melting temp, IR-spectroscopy, UV-vis spectrum, and TLC plating. The mass of caffeine produced from individual coffee brands were measured and compared. It was hypothesized that robusta coffee beans would yield more caffeine than arabica coffee beans. The expected results verify those claims as the data demonstrates that the amount of caffeine extracted from 10 grams of robusta coffee would be around .8021 grams, while the amount of caffeine extracted from 10 grams of arabica coffee would be around .4321 grams. The IR graph, UV-vis graph, and TLC plate were conducted to verify the identity of the product. The predicted IR graph, UV-vis graph, and TLC plate closely matched with the literature values, which indicates that the product produced is pure caffeine. One source of error that could skew the data could be the presence of impurities from the coffee beans that react in solution while we are trying to extract the caffeine. The broader impact of this review is that by understanding the caffeine content in different products, the medical and scientific field can further determine the difference in health effects between excess and optimal caffeine consumption to the human body. Additionally, scientists can research various medical usages of caffeine to help different patients with sleep disorders.

ENHANCEMENT OF REDUCED GRAPHENE OXIDE BOLOMETRIC PHOTORESPONSE VIA ADDITION OF GRAPHENE QUANTUM DOTS

Reduced graphene oxide (rGO) has attracted interest in its potential application in large area photodetectors owing to its ease of manufacture and wideband optical absorbance. Here, we report that thin rGO films produced via vacuum filtration of GO followed by reduction by immersion in L-ascorbic acid are capable of sensing light through a bolometric mechanism. The photoresponse of these rGO thin films can be further enhanced by dropcasting graphene quantum dots (GQDs) on the rGO surface. These GQDs were observed to increase the opacity of the rGO film and hence its absorptivity of light, thereby enabling a significant increase in the photoresponse of the device.

Optimizing Nannochloropsis Growing Conditions for Biodiesel Production Through Analysis of Lipid Content

<div><div><div><div><p>The algae are grown in two groups of three 2.5 L glass jugs spanning three concentration levels of nitrates and phosphates. A growing “f/2” medium is kept constant across trials. The algae are harvested using a flocculating solution of aluminum sulfate and vacuum filtration. The oven dry weight is obtained. Acid catalyzed in situ transesterification is used to achieve maximum conversion of fatty acids into fatty acid methyl esters (FAME), which are then analyzed using gas chromatography (GC) equipped with a flame ionization detector. Supelco 37-component FAME standards were used for identification and quantification of the FAMEs. Methyl pentadecanoate was used as an internal standard for quantification. HPLC-grade hexane used as solvent in GC analysis.</p></div></div></div></div>

Optimizing Nannochloropsis Growing Conditions for Biodiesel Production Through Analysis of Lipid Content

<div><div><div><div><p>The algae are grown in two groups of three 2.5 L glass jugs spanning three concentration levels of nitrates and phosphates. A growing “f/2” medium is kept constant across trials. The algae are harvested using a flocculating solution of aluminum sulfate and vacuum filtration. The oven dry weight is obtained. Acid catalyzed in situ transesterification is used to achieve maximum conversion of fatty acids into fatty acid methyl esters (FAME), which are then analyzed using gas chromatography (GC) equipped with a flame ionization detector. Supelco 37-component FAME standards were used for identification and quantification of the FAMEs. Methyl pentadecanoate was used as an internal standard for quantification. HPLC-grade hexane used as solvent in GC analysis.</p></div></div></div></div>