Internal Hollow Research Articles

Electrochemical behaviors of porous spherical spinel H1.6Mn1.6O4 with high Li+ adsorption capacity

A self-assembled spherical H1.6Mn1.6O4 adsorbent with surface porous and internal hollow structure was successfully synthesized. Due to the special surface porous and internal hollow structure, the adsorbent exposes channels and interfaces for ions migration and ad/desorption, and also provides sites for charge transfer. At an initial Li+ concentration of 400 mg/L, the spherical adsorbent adsorption capacity of lithium can efficiently reach an extreme 47.54 mg/g in 360 min (the traditional adsorption route is 44.36 mg/g at 2880 min) without alkaline assistance by applying the electrochemical adsorption technique. In the multiple MCl (M = Li, Na, K, Rb, Cs) solution with each metal ion molar concentration of 14.41 mmol/L, the adsorbent adsorption capacity keeps 89.71% of a single LiCl solution. After the 5th cycle, the adsorption capacity to lithium remains at 94.98% (the traditional adsorption route is 86.65%) of the initial adsorption value. According to the analysis of cyclic voltammetry (CV) curves, it is found that the key kinetic factor limiting the adsorption rate is that the ions migration rate cannot catch up with the electrons transfer rate during the adsorption process. Furthermore, the electric field self-promotes the pH of the solution, and the corresponding alkaline environment is favorable for the adsorption behaviors. In the actual salt lakes brine, the 1st electrochemical adsorption capacity of the adsorbent for lithium is 3.26 mmol/g (Salt lake B), and the 5th adsorption capacity is 83.74% of the 1st adsorption value.

Enzyme-Powered Hollow Nanorobots for Active Microsampling Enabled by Thermoresponsive Polymer Gating.

Achieving molecular sample capture at micro/nanoscales while integrating functions of controllable loading and real-time monitoring of cargo molecules is of great significance in the development of intelligent micro/nanorobots. Herein, we prepare a temperature-responsive microsampling nanorobot by encapsulating metal (Au) nanodots inside hollow mesoporous silica nanoparticles and grafting a temperature-responsive polymer, poly(N-isopropylacrylamide), on their external surface. The molecular gate of nanochannels accessing the internal hollow reservoir can be switched between "open" and "closed" states by regulating the temperature, allowing on-demand loading and releasing of small molecules. The internally embedded surface-enhanced Raman scattering hotspots of gold nanodots can serve as sensing probes for real-time detection of the molecular cargo load inside the hollow nanorobots. Furthermore, we demonstrate temperature-dependent self-propulsion behavior of the nanorobots driven by enzymatic reactions. The active motion behavior can favorably regulate the loading efficiency of molecular cargos. In addition, by further introducing the magnetic component Ni, the nanorobots can accomplish effective transportation of cargo molecules by magnetic guidance under real-time Raman monitoring. The current strategy is expected to provide a manipulable nanorobot platform for precise biomedical sampling, which holds promising potential for disease diagnosis or controlled drug delivery in precision medicine.

Effective adsorption and acceleration redox conversion towards lithium polysulfide by nanorod-like Sb-doped SnO2 nanofibers for high-performance lithium-sulfur battery

Lithium-sulfur batteries (LSBs) have attracted increasing attention due to high theoretical energy density and low cost of sulfur. However, there are still many challenges regarding sulfur cathodes such as the “shuttle effect” of polysulfides, insulating properties of sulfur and Li2S2/Li2S, and the sluggish redox kinetics. In this study, the nanorod-like Sb-doped SnO2 nanofibers (ATO NFs) with hollow structure were prepared by the electro-blown spinning technology and calcination processes, and used as a sulfur host for cathode materials. The internal hollow structure and the nanorod-like structure on the surface of the nanofibers with the increased specific surface area are beneficial to load sulfur and improve transport channels of electrons and lithium ions. And the hollow nanofibers also can well accommodate to huge volume changes in the reaction process. More importantly, the ATO NFs with hollow structure have good physical confinement and chemical adsorption performance to polysulfides. Based on these merits, the ATO NFs composite cathode exhibits a high initial discharge specific capacity of 765.3 mAh g−1 and maintains 550.6 mAh g−1 after 900 cycles at a rate of 2 C with 1.9 mg cm−2 sulfur loading. More importantly, high initial area discharge specific capacity of the electrode is 5.5 mAh cm−2 at 0.1 C with sulfur loading of 5.6 mg cm−2. Even, at a rate of 0.2 C, the area capacity still is stabilized at 3.5 mAh cm−2 after 100 cycles. The work illustrates that the ATO NFs for LSBs exhibit good cycling stability over a long period of time, entering the ranks of high performance and ultra-stable capacity. And it also facilitate to expand the scope of application of ATO NFs in other related energy storage fields.

Fundamental understanding and catalytic applications of hollow MFI-type zeolites

In this review, we summarize the fundamental understanding and recent progresses on hollow MFI-type zeolite synthesis, hollow cavity formation mechanism, and mass transport/catalytic performance intensification, especially from the viewpoints of industrial application. Obviously, introduction of hollow cavities into the micropores of MFI-type zeolites significantly facilitates both internal mass transport and catalytic performance in many Brönsted or Lewis acid catalyzed reactions, i.e. catalytic oxidation, methanol to hydrocarbons and catalytic cracking reaction. It is majorly assigned to the shortened diffusion path length within zeolite crystal, while there is no change of external surface, thus leading to lower mass transport energy barrier. In general, hollow zeolites are synthesized by two strategies, including selective desilication method and in-situ dissolution-recrystallization (also remarked as crystalline rearrangement) method, ascribing to the reassembly of dissolved species with low aggregation under the effect of organic templates in hydrothermal conditions in latter process. Notably, selective dissolution is the driving force of these two synthesis routes, thus it is key to tune the composition and dispersion of framework elements and intracrystalline defects for controlling the size and distribution of internal hollow cavities. Moreover, through rearrangement, previously impregnated metal nanoparticles with tunable composition and size can be encapsulated within zeolite crystal, thus showing relatively high thermal stability and catalytic activity in catalytic oxidation reactions, selective hydrogenation, cross-coupling, esterification, and C1 transformation.

Polypyrrole Modified MoS2 Nanorod Composites as Durable Pseudocapacitive Anode Materials for Sodium-Ion Batteries.

As a typical two-dimensional layered metal sulfide, MoS2 has a high theoretical capacity and large layer spacing, which is beneficial for ion transport. Herein, a facile polymerization method is employed to synthesize polypyrrole (PPy) nanotubes, followed by a hydrothermal method to obtain flower-rod-shaped MoS2/PPy (FR-MoS2/PPy) composites. The FR-MoS2/PPy achieves outstanding electrochemical performance as a sodium-ion battery anode. After 60 cycles under 100 mA g−1, the FR-MoS2/PPy can maintain a capacity of 431.9 mAh g−1. As for rate performance, when the current densities range from 0.1 to 2 A g−1, the capacities only reduce from 489.7 to 363.2 mAh g−1. The excellent performance comes from a high specific surface area provided by the unique structure and the synergistic effect between the components. Additionally, the introduction of conductive PPy improves the conductivity of the material and the internal hollow structure relieves the volume expansion. In addition, kinetic calculations show that the composite material has a high sodium-ion transmission rate, and the external pseudocapacitance behavior can also significantly improve its electrochemical performance. This method provides a new idea for the development of advanced high-capacity anode materials for sodium-ion batteries.

The forewing of a black cicada Cryptotympana atrata (Hemiptera, Homoptera: Cicadidae): Microscopic structures and mechanical properties.

Insects in nature flap their wings to generate lift force and driving torque to adjust their attitude and control stability. An insect wing is a biomaterial composed of flexible membranes and tough veins. In this paper, we study the microscopic structures and mechanical properties of the forewing of the black cicada, Cryptotympana atrata. The thickness of the wing membranes and the diameter of veins varied from the wing root to the tip. The thickness of the wing membranes ranged from 6.0 to 29.9μm, and the diameter of the wing veins decreased in a gradient from the wing root to the tip, demonstrating that the forewing of the black cicada is a nonuniform biomaterial. The elastic modulus of the membrane near the wing root ranged from 4.45 to 5.03 GPa, which is comparable to that of some industrial membranes. The microstructure of the wing vein exhibited a hollow tubular structure with flocculent structure inside. The "fresh" sample stored more water than the "dry" sample, resulting in a significant difference in the elastic modulus between the fresh and dried veins. The different membrane thicknesses and elastic moduli of the wing veins near the root and tip resulted in varied degrees of deformation on both sides of the flexion line of the forewing during twisting. The measurements of the forewing of the cicada may serve as a guide for selecting airfoil materials for the bionic flapping-wing aircraft and promote the design and manufacture of more durable bionic wings in the future. RESEARCH HIGHLIGHTS: The distribution of the wing vein diameter and the wing membrane thickness indicated that the forewing of Cryptotympana atrata is composed of heterogeneous materials. The wing membrane and the outer wall of the wing vein are the layered structure with multilayer fibers, which has a great significance for improving the ability of the forewing to sustain aerodynamic loads. The elastic modulus of the wing membrane near the wing root is in the range of 4.45-5.03GPa, which is comparable to that of membranes manufactured by industries. This is a suitable reference for selecting materials for making bionic aircraft wings. We proved that the elastic moduli of the "fresh" and "dry" wing veins differ greatly compared with those of the wing membrane. Because the wing vein microstructure exhibits an internal hollow tubular structure with flocculent structure inside, the "fresh" sample stores more water than the "dry" sample. The wing membrane near the wing root is thicker and reinforced by the main wing vein with a high elastic modulus. This renders the region near the wing root difficult to deform. The membrane far from the wing root is thinner and the elastic modulus of the nearby wing veins is smaller, making them more flexible.

PH-responsive mesoporous Fe2O3–Au nanomedicine delivery system with magnetic targeting for cancer therapy

Chemotherapy is the prime tool for the clinical treatment of cancer. The efficiency of treatment has been greatly improved with the assistance of nanomedicine delivery systems. However, it still meets the challenge of inefficient drug delivery and damage to normal tissues caused by uncontrolled drug release. Considering the various processes of nanomedicine acting on cancer cells, a pH-responsive mesoporous Fe2O3–Au nanomedicine delivery system with magnetic targeting was designed to achieve controlled drug release and improve the safety and efficiency. Fe2O3 particles were constructed with external mesopores and internal hollow structures, while Au nanoparticles were connected on the surface of Fe2O3 particles through pH-responsive valence bonds to encapsulate the drug. The Fe2O3–Au nanomedicine delivery system was equipped with magnetic targeting function, which could be induced by an external magnetic field to increase the drug concentration to kill cancer cells as well as reduce damage to normal cells. Meanwhile, based on the pH-responsive feature, the drug embedded could only be released in the weakly acidic condition of the cancer environment, while the nanomedicine delivery system remained closed in normal tissues. The Fe2O3–Au nanomedicine delivery system possessed the functions of pH responsiveness and magnetic targeting, enhancing safety and efficiency and providing a promising method for cancer therapy.

Concurrent thermal conductivity measurement and internal structure observation of individual one-dimensional materials using scanning transmission electron microscopy

The thermal conductivity of individual nanomaterials can vary from sample to sample due to the difference in geometries and internal structures, and thus, concurrent structure observation and thermal conductivity measurement at the nanoscale are highly desired but challenging. Here, we have developed an experimental method that allows concurrently the in situ thermal conductivity measurement and the real-time internal structure observation of a single one-dimensional (1D) material using scanning transmission electron microscopy (STEM) in a scanning electron microscope. In this method, the two ends of the 1D nanomaterial are bonded on a tungsten probe and a suspended platinum nanofilm, respectively. The platinum nanofilm serves simultaneously as a heater and a resistance thermometer, ensuring highly sensitive thermal measurements. The platinum nanofilm is fabricated on the edge of the silicon wafer so that the electron beam can transmit through the 1D material and be detected by the STEM detector, which caters for real-time observation of the inner nanostructure. Using this method, we in situ measured the thermal conductivities of two cup-stacked carbon nanotubes and concurrently observed the internal hollow structures. We found that the sample with more structural disorders had a lower thermal conductivity. Our measurement method can pave the way to the sample-by-sample elucidation of the structure–property relationship for 1D materials.

Preparation of Li1.2Ni0.2Mn0.6O2 hollow stratified sphere by self-template method and surface vulcanization

As promising cathode materials in Li-ion batteries, Li-rich layered oxides still suffer from unsatisfactory first Coulomb efficiency and cyclic stability. Herein, the hollow structure of Li1.2Mn0.6Ni0.2O2 was purposefully designed by a self-template method with MnO2 as the precursor. Then, the Ni-Mn sulfides coated layers was formed on the surface of the material by avulcanization with thioacetamide. It is proved that the Ni-Mn sulfides are evenly distributed on the surface, and the vulcanization process enlarges the internal hollow volume, which greatly improved the electrochemical performance of cathode materials. The optimal sample was delivered an initial discharge specific capacities of 270.2 mA h g−1 with highest coulomb efficiency (79.3 %) and remarkable cycling stability of 95.6% capacity retention after 100 cycles at 0.1C.

Enzymeless copper microspheres@carbon sensor design for sensitive and selective acetylcholine screening in human serum

Follow up of neuronal disorders, such as Alzheimer’s and Parkinson’s diseases using simple, sensitive, and selective assays is urgently needed in clinical and research investigation. Here, we designed a sensitive and selective enzymeless electrochemical acetylcholine sensor that can be used in human fluid samples. The designed electrode consisted of a micro spherical construction of Cu-metal decorated by a thin layer of carbon (CuMS@C). A simple and one-pot synthesis approach was used for Cu-metal controller formation with a spherical like structures. The spherical like structure was formed with rough outer surface texture, circular build up, homogeneous formation, micrometric spheres size (0.5 −1 µm), and internal hollow structure. The formation of a thin layer of carbon materials on the surface of CuMS sustained the catalytic activity of Cu atoms and enriched negatively charge of the surface. CuMS@C acted as a highly active mediator surface that consisted of Cu metal as a highly active catalyst and carbons as protecting, charge transport, and attractive surface. Therefore, the CuMS@C surface morphology and composition played a key role in various aspects such as facilitated ACh diffusion/loading, increased the interface surface area, and enhanced the catalytic activity. The CuMS@C acted as an electroactive catalyst for ACh electrooxidation and current production, due to the losing of two electrons. The fabricated CuMS@C could be a highly sensitive and selective enzymeless sensor for detecting ACh with a detection limit of 0.1 µM and a wide linear range of 0.01 – 0.8 mM. The designed ACh sensor assay based on CuMS@C exhibited fast sensing property as well as sensitivity, selectivity, stability, and reusability for detecting ACh in human serum samples. This work presents the design of a highly active electrode surface for direct detection of ACh and further clinical investigation of ACh levels.

Asymmetric polymersomes, from the formation of asymmetric membranes to the application on drug delivery

Nano drug delivery systems have attracted researchers' growing attention and are gradually emerging into the public views. More and more nano-formulations are being approved for marketing or clinical use, representing the field's booming development. Copolymer self-assembly systems such as micelles, nanoparticles, polymersomes occupy a prominent position in the field of nano-drug delivery carriers. Among them, polymersomes, unlike micelles or nanoparticles, resemble liposomes' structure and possess large internal hollow hydrophilic reservoirs, allowing them to carry hydrophilic drugs. Nevertheless, their insufficient drug loading efficiency and unruly self-assembly morphology have somewhat constrained their applications. Especially for the delivery of biomacromolecule such as peptides, the encapsulation efficiency is always considered to be a formidable obstacle, even if the enormous hydrophilic core would render the polymersomes to have considerable potential in this regard. Reassuringly, the emergence of asymmetric polymersomes holds the prospect of solving this problem. With the development of synthetic technology and a deeper understanding of the self-assembly process, the asymmetric polymersomes which are with different inner and outer shell composition have been gradually recognized by researchers. It has made possible elevated drug loading, more controllable assembly processes and release performance. The internal hydrophilic blocks different from the outer shell could be engineered to have a more remarkable affinity to the cargos or could contain a non-watery aqueous phase to enable the thermodynamically preferred encapsulation of cargos, which would allow for a substantial improvement in drug encapsulation efficiency compared to the conventional approach. In this paper, we aim to deepen the understanding to asymmetric polymersomes and lay the foundation for the development of this field by describing four main elements: the mechanism of their preparation and asymmetric membrane formation process, the characterization of asymmetric membranes, the efficient drug loading, and the special stimulus-responsive release mechanism.

Flammulina velutipes-like Co@NCNTs enhancing the electromagnetic wave absorption performance

Magnetic nitrogen-doped carbon nanotubes have been recognized as promising microstructures for electromagnetic wave absorption, benefiting from the internal hollow structure, excellent electrical conductivity and easy functionalization. Herein, a new composite composed of the thin-wall carbon nanotubes coated with the cobalt nanoparticles (hereafter labelled as: Co@NCNTs) on the tip was designed and synthesized through high temperature pyrolysis process. Revealed by scanning electron microscopy and X-ray photoelectron spectroscopy, the geometric and electronic structures of product were susceptible to the carbonization temperature. With the multiple dielectric polarization relaxations, higher magnetism and good impedance matching, the flammulina velutipes-like Co@NCNTs-700 exhibited the strongest dielectric loss, magnetic loss and electromagnetic wave absorption performance. The minimum reflection loss value and effective absorption bandwidth was determined to be −21.0 dB at 4.96 GHz and 5.28 GHz, respectively, superior to the previous reports. Furthermore, the thickness is at 2 mm and the filler mass loading is only 10%. Therefore, our present Co@NCNTs materials will be an ultralight material as potential high-efficiency EMW absorber.

A hybrid molecular peapod of sp2- and sp3-nanocarbons enabling ultrafast terahertz rotations

The internal hollow space of carbon nanotubes provides a unique nanometre-sized space to capture various molecular entities. The inner space circumfused by sp2-carbon networks can also encapsulate diamondoid molecules to afford sp2/sp3-hybrid nanocarbon peapods that have recently emerged as unique nanostructures. In this study, the sp2/sp3-hybrid peapods have been mimicked by adopting a cylindrical molecule and the smallest diamondoid, i.e., adamantane, to demonstrate the existence of ultrafast rotational motion. The solid-state rotational frequency is measured by NMR spectroscopy to record 1.06 THz that is, to the best of our knowledge, the largest value recorded for solid-state rotations of molecules. Theoretical calculations reveal that multivalent CH-π hydrogen bonds anchored the diamondoid guest on the π-wall of the cylindrical host. The weak hydrogen bonds are prone not only to cleave but also to regenerate at the interfaces, which give freedom to the guest for ultrafast isotropic rotations in the inertial regime.

Size-Dependent Synthesis of Hollow Co3O4 Nanocubes Derived from Co-Fe PBA as Battery-Type Electrode Materials for Hybrid Supercapacitors

Hollow nanostructures with enlarged surface areas are highly attractive electrode materials for supercapacitors. In this work, the size-dependent synthesis of hollow Co3O4 nanocubes via a facile ionic exchange reaction between Co-Fe Prussian blue analogues (PBAs) and alkali solution is reported. By adjusting the concentration of sodium citrate to control the reaction kinetics during nucleation and growth, four different sizes of Co-Fe PBAs were synthesized. It was also found that a Co-Fe PBA of about 140 nm can be easily converted into a well-defined internal hollow structure, while Co-Fe PBAs with smaller or larger sizes are challenged in generating a hollow structure. Benefitting from the inner voids and thin shell architecture, the derived hollow Co3O4 nanocubes exhibit a high specific capacity of 296.6C cm−2 at 2 mA cm−2, and a rate capability of 64.5% when the current density is increased to 60 mA cm−2. Furthermore, a hybrid supercapacitor (HSC) was fabricated with hollow Co3O4 nanocubes as the cathode and activated carbon as the anode, respectively. The HSC provided a maximum energy density of 14.1 Wh kg−1 at 464.7 W kg−1. Moreover, it retained the excellent cycling stability of 85.7% of the original capacity over 5000 continuous charging and discharging processes.

Flexural behaviour of hollow concrete beams under three points loading: Experimental and numerical study

This study examines the flexural behaviour of hollow reinforced concrete (RC) beams experimentally, numerically, and analytically. The experimental work was accompanied to study the influence of internal concrete hollow core size on the flexural response of RC beams. A control beam with a solid section and three other specimens having a hollow core area of 3%, 7%, and 10% of the beam cross-section area were tested. During loading, the crack patterns for all the specimens were recorded. The results indicated that using less than 10% of the beam cross-section as the hollow part didn’t considerably affect the failure load of the RC beams. In conclusion, the concrete core didn’t contribute to the capacity of the RC beams; however, it affected the cracking pattern, i.e. size and height. A numerical model was implemented using ABAQUS to simulate the behaviour of the hollow RC beams. The numerical model accurately expected the response of the tested RC beams. Using the validated model, a parametric study was complemented to study the influence of the hollow size and location on the RC beam response.

Improving Na+ transport kinetics and Na+ storage of hierarchical rhenium-nickel sulfide (ReS2@NiS2) hollow architecture by assembling layered 2D-3D heterostructures

Mixed metal sulfides have been widely used as anode material of sodium-ion batteries (SIBs) because of their excellent conductivity and sodium ion storage performance. Herein, ReS2@NiS2 heterostructures have been triumphantly designed and prepared through anchoring ReS2 nanosheet arrays on the surface of NiS2 hollow nanosphere. Specifically, the carbon nanospheres was used as hard template to synthesize NiS2 hollow spheres as the substrate and then the ultrathin two-dimensional ReS2 nanosheet arrays were uniformly grown on the surface of NiS2. The internal hollow property provides sufficient space to relieve the volume expansion, and the outer two-dimensional nanosheet realizes the rapid electron transport and insertion/extraction of Na+. Owing to the great improvement of the transport kinetics of Na+, NiS2@ReS2 heterostructure electrode can achieve a high specific capacity of 400 mAh/g at the high current density of 1 A/g and still maintain a stable cycle stability even after 220 cycles. This hard template method not only paves a new way for the design and construct binary metal sulfide heterostructure electrode materials with outstanding electrochemical performance for Na+ batteries but also open up the potential applications of anode materials of SIBs.

Migration of mineral oil hydrocarbons from food contact papers into food simulants and extraction from their raw materials

ABSTRACT To determine the occurrence of mineral oil hydrocarbons (MOH) in food contact papers in China, and to investigate the potential sources of MOH contamination, a total of 159 food contact papers and raw materials were analysed by off-line solid-phase extraction-gas chromatography flame ionisation detection (SPE-GC-FID) and a GC-MS method. The migration of MOH from food contact papers into Tenax, olive oil or 50% ethanol under the worst foreseeable conditions of use was determined. The results indicated that the occurrence of MOH in China is of a potential health risk concerning the migration of mineral oil saturated hydrocarbons (MOSH) and mineral oil aromatic hydrocarbons (MOAH) which were detected in 82.6% and 50.4% of samples, respectively. Migration of MOSH from 47.9% of samples was higher than 2 mg/kg and migration of MOAH from 32.2% samples exceeded 0.5 mg/kg in case of the worst foreseeable condition of use. The highest mean migration of MOSH and MOAH were found in packaging papers for long-term storage (more than 6 months), with mean migration of 91.2 mg/kg and 1.4 mg/kg, respectively. Migration of MOH from printed paper was considerably higher than that of unprinted paper, validating previous findings that the printing ink is the predominant source of MOH contamination in food contact papers. Migration of MOH from paper bowls used for packing instant noodles was relatively low, suggesting the internal hollow layer may be acting as a functional barrier that could block the transfer of MOH (up to C28) through the gas phrase, even though the outer layer was made from recycled paper. High concentrations of MOSH and MOAH were also detected in de-foamers, adhesives and rosin sizing agents, indicating that the MOH contamination caused by the use of raw materials and additives should also be taken into consideration.

Sculpturing solid polymer spheres into internal gridded hollow carbon spheres under controlled pyrolysis micro-environment

Porous carbon spheres with an internal gridded hollow structure and microporous shell have always been attractive as carbon hosts for electrochemical energy storage. Such carbon hosts can limit active species loss and enhance electronic conductivity throughout the entire framework. Herein, a synthesis approach of internal gridded hollow carbon spheres is developed from solid polymer spheres rather than originally gridded polymer spheres under a controlled pyrolysis micro-environment. The crucial point of this approach is the fabrication of a silica fence around solid polymer spheres, under which the free escaping of the pyrolysis gas will be partly impeded, thus offering a reconstitution opportunity for an internal structure of solid polymer spheres. As a result, the interior of carbon spheres is sculptured into a gridded hollow structure with microporous skin. Furthermore, the size and density of carbon-bridge grids can be modulated by altering the crosslinking degree of polymer spheres and varying pyrolysis conditions. Such gridded hollow carbon spheres show good performance as sulfur hosts for Li-S battery.

EXPERIMENTAL AND NUMERICAL STUDY OF INSERTING AN INTERNAL HOLLOW CORE TO FINNED HELICAL COIL TUBE-SHELL HEAT EXCHANGER

In the present study, an experimental study and a numerical method are used to simulate the effect of utilizing finned helical coil heat exchanger horizontally oriented with and without internal hollow core inside the shell and monitoring the heat transfer intensification behavior and performance enhancement, by using ANSYS FLUENT 2019R3 package. The working fluid in the inlet side of the coil will be superheated vapor refrigerant (R410a) after the compression stage of the air conditioner (1TR) split type, the working fluid in the shell side is water with various flow rates (1,2 and 3) LPM. Found that when using a heat exchanger with internal hollow core reduces the time needed to reach the steady-state outlet temperature and directly proportional to the size of the core by 20% and slightly increasing the water outlet temperature by 5%.

Construction of protein-loadable protein cages using the hybrid proteins of the oleosin hydrophobic domain and hydrophilic dimeric coiled-coil

We successfully designed the bilayer-capsule-formable OLE-ZIP proteins by fusing the dimeric coiled coil motif (NZ and CZ) [1] and the hydrophobic domain OLE(56–106) of the sunflower-derived oleosin. In order to improve handling in a buffer, we characterized the fusion protein with thioredoxin, Trx-OLE-ZIP as an alternative. Based on the emulsion method, Trx-OLE-ZIP could successfully form stable liposome-kind bilayer capsules, with empty hollow. Furthermore, it could encapsulate other water-soluble proteins, such as GFP, to the internal hollow with a buffer of inner aqueous phase. By mutating four conserved Thr residues (Thr59, Thr66, Thr97, and Thr104) in the OLE(56–106) domain with Asp residues, we further successfully constructed the pH-sensitive mutant, Trx-OLE-D-ZIP. Under weakly acidic conditions at pH = 5, Trx-OLE-D-ZIP could maintain a spherical cage-morphology. By shifting the solution pH to basic (pH = 9), the protein-cages spontaneously collapsed and released the loaded proteins.