scholarly journals A mechanically adaptive hydrogel with a reconfigurable network consisting entirely of inorganic nanosheets and water

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Koki Sano ◽  
Naoki Igarashi ◽  
Yasuo Ebina ◽  
Takayoshi Sasaki ◽  
Takaaki Hikima ◽  
...  
Keyword(s):  
Room Temperature ◽  
Soft Materials ◽  
Inorganic Materials ◽  
Thermally Induced ◽  
3D Network ◽  
Abrupt Changes ◽  
Van Der Waals Attraction ◽  
Living Organisms ◽  
Restricted Mobility ◽  
Gel Transition

AbstractAlthough various biomimetic soft materials that display structural hierarchies and stimuli responsiveness have been developed from organic materials, the creation of their counterparts consisting entirely of inorganic materials presents an attractive challenge, as the properties of such materials generally differ from those of living organisms. Here, we have developed a hydrogel consisting of inorganic nanosheets (14 wt%) and water (86 wt%) that undergoes thermally induced reversible and abrupt changes in its internal structure and mechanical elasticity (23-fold). At room temperature, the nanosheets in water electrostatically repel one another and self-assemble into a long-periodic lamellar architecture with mutually restricted mobility, forming a physical hydrogel. Upon heating above 55 °C, the electrostatic repulsion is overcome by competing van der Waals attraction, and the nanosheets rearrange into an interconnected 3D network of another hydrogel. By doping the gel with a photothermal-conversion agent, the gel-to-gel transition becomes operable spatiotemporally on photoirradiation.

A bioprinted composite hydrogel with controlled shear stress on cells

2020 ◽  
pp. 095441192097668
Author(s):  
Amirhossein Bakhtiiari ◽  
Rezvan Khorshidi ◽  
Fatemeh Yazdian ◽  
Hamid Rashedi ◽  
Meisam Omidi
Keyword(s):  
Shear Stress ◽  
Cell Viability ◽  
Room Temperature ◽  
Degradation Rate ◽  
Diffusion Rate ◽  
Sol Gel ◽  
Three Dimensional ◽  
Simulation Software ◽  
Sol Gel Transition ◽  
Gel Transition

In recent decades, three dimensional (3D) bio-printing technology has found widespread use in tissue engineering applications. The aim of this study is to scrutinize different parameters of the bioprinter – with the help of simulation software – to print a hydrogel so much so that avoid high amounts of shear stress which is detrimental for cell viability and cell proliferation. Rheology analysis was done on several hydrogels composed of different percentages of components: alginate, collagen, and gelatin. The results have led to the combination of percentages collagen:alginate:gelatin (1:4:8)% as the best condition which makes sol-gel transition at room temperature possible. The results have shown the highest diffusion rate and cell viability for the cross-linked sample with 1.5% CaCl2 for the duration of 1 h. Finally, we have succeeded in printing the hydrogel that is mechanically strong with suitable degradation rate and cell viability.

Evolution of crystal structure of dual layered molecular conductor (ET)4ZnBr4(C6H4Cl2) with temperature

CrystEngComm ◽  
2021 ◽  
Author(s):  
Gennady V. Shilov ◽  
Elena I. Zhilyaeva ◽  
Sergey M. Aldoshin ◽  
Alexandra M Flakina ◽  
Rustem B. Lyubovskii ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Electrical Resistivity ◽  
Single Crystal ◽  
Room Temperature ◽  
Organic Conductor ◽  
X Ray Diffraction ◽  
X Ray ◽  
Resistivity Measurements ◽  
Molecular Conductor ◽  
Abrupt Changes

Electrical resistivity measurements of a dual layered organic conductor (ET)4ZnBr4(1,2-C6H4Cl2) above room temperature show abrupt changes in resistivity at 320 K. Single-crystal X-ray diffraction studies in the 100-350 K range...

Thiol-mediated etching of gold nanorods as a neoteric strategy for room-temperature and multicolor detection of nitrite and nitrate

2021 ◽  
Author(s):  
Marzieh Sepahvand ◽  
Forough Ghasemi ◽  
Hossein Mirseyed Hosseini
Keyword(s):  
Human Health ◽  
Gold Nanorods ◽  
Room Temperature ◽  
Scientific Communities ◽  
Negative Impacts ◽  
Living Organisms

The excessive presence of nitrite and nitrate in the environmental matrixes has raised concerns among the scientific communities due to their negative impacts on human health and living organisms. Considering...

Iron(II) and Nickel(II) Complexes of 2,6-Di(thiazol-2-yl)pyridine and Related Ligands

1991 ◽  
Vol 44 (8) ◽  
pp. 1041 ◽  
Author(s):  
AT Baker ◽  
P Singh ◽  
V Vignevich
Keyword(s):  
High Spin ◽  
Room Temperature ◽  
Spin Transition ◽  
Magnetic Behaviour ◽  
Diethyl Acetal ◽  
Thermally Induced ◽  
Field Strengths

2,6-Di(thiazol-2-yl]pyridine (1a), 2,6-di(4-methylthiazol-2-yl)pyridine (1b) and 2,6-di(2-imid-azolin-2-yl)pyridine (3) have been prepared by the reaction of pyridine-2,6-dicarbothioamide with bromoacetaldehyde diethyl acetal, bromoacetone and ethylenediamine, severally. Bis ( ligand ) iron(II) and nickel(II) complexes of all ligands have been prepared. The bis ( ligand ) iron(II) complexes of (1a) and (3) are low-spin whereas that of (1b) is high-spin at room temperature and undergoes a thermally induced spin transition. The field strengths of the ligands , determined from the spectra of their nickel(II) complexes, correlate well with the observed magnetic behaviour of their iron(II) complexes. The field strengths of (1a) and (1b) are found to be marginally less than those of the isomeric ligands 2,6-di(thiazol-4-yl)pyridine (2a) and 2,6-di(2-methylthiazol-4-yl)pyridine (2b).

scholarly journals Metal-organic magnets with large coercivity and ordering temperatures up to 242°C

Science ◽  
2020 ◽  
Vol 370 (6516) ◽  
pp. 587-592 ◽  
Author(s):  
Panagiota Perlepe ◽  
Itziar Oyarzabal ◽  
Aaron Mailman ◽  
Morgane Yquel ◽  
Mikhail Platunov ◽  
...  
Keyword(s):  
Metal Ions ◽  
Room Temperature ◽  
Building Blocks ◽  
Inorganic Materials ◽  
Coordination Networks ◽  
Critical Temperatures ◽  
Considerable Success ◽  
Organic Magnets ◽  
Metal Organic ◽  
Constituent Elements

Magnets derived from inorganic materials (e.g., oxides, rare-earth–based, and intermetallic compounds) are key components of modern technological applications. Despite considerable success in a broad range of applications, these inorganic magnets suffer several drawbacks, including energetically expensive fabrication, limited availability of certain constituent elements, high density, and poor scope for chemical tunability. A promising design strategy for next-generation magnets relies on the versatile coordination chemistry of abundant metal ions and inexpensive organic ligands. Following this approach, we report the general, simple, and efficient synthesis of lightweight, molecule-based magnets by postsynthetic reduction of preassembled coordination networks that incorporate chromium metal ions and pyrazine building blocks. The resulting metal-organic ferrimagnets feature critical temperatures up to 242°C and a 7500-oersted room-temperature coercivity.

scholarly journals Development of Photocrosslinkable Urethane-Doped Polyester Elastomers for Soft Tissue Engineering

2011 ◽  
Vol 1 (1) ◽  
pp. 18-31 ◽  
Author(s):  
Yi Zhang ◽  
Richard T. Tran ◽  
Dipendra Gyawali ◽  
Jian Yang
Keyword(s):  
Mechanical Properties ◽  
Tissue Engineering ◽  
Soft Tissue ◽  
Hexamethylene Diisocyanate ◽  
Elongation At Break ◽  
Thermally Induced ◽  
Molar Ratios ◽  
3D Network ◽  
Soft Tissue Engineering

Finding an ideal biomaterial with the proper mechanical properties and biocompatibility has been of intense focus in the field of soft tissue engineering. This paper reports on the synthesis and characterization of a novel crosslinked urethane-doped polyester elastomer (CUPOMC), which was synthesized by reacting a previously developed photocrosslinkable poly (octamethylene maleate citrate) (POMC) prepolymers (pre-POMC) with 1,6-hexamethylene diisocyanate (HDI) followed by thermo- or photo-crosslinking polymerization. The mechanical properties of the CUPOMCs can be tuned by controlling the molar ratios of pre-POMC monomers, and the ratio between the prepolymer and HDI. CUPOMCs can be crosslinked into a 3D network through polycondensation or free radical polymerization reactions. The tensile strength and elongation at break of CUPOMC synthesized under the known conditions range from 0.73±0.12MPa to 10.91±0.64MPa and from 72.91±9.09% to 300.41±21.99% respectively. Preliminary biocompatibility tests demonstrated that CUPOMCs support cell adhesion and proliferation. Unlike the pre-polymers of other crosslinked elastomers, CUPOMC pre-polymers possess great processability demonstrated by scaffold fabrication via a thermally induced phase separation method. The dual crosslinking methods for CUPOMC pre-polymers should enhance the versatile processability of the CUPOMC used in various conditions. Development of CUPOMC should expand the choices of available biodegradable elastomers for various biomedical applications such as soft tissue engineering.

Thermally induced transformations of Fe oxide-stabilized residues from waste incineration

2001 ◽  
Vol 65 (5) ◽  
pp. 635-643 ◽  
Author(s):  
M. A. Sørensen ◽  
C. Bender Koch
Keyword(s):  
Heavy Metals ◽  
Room Temperature ◽  
Waste Incineration ◽  
Oxide Phase ◽  
Waste Incinerator ◽  
Air Pollution Control ◽  
Fe Oxide ◽  
Thermally Induced ◽  
Co Precipitation ◽  
Reducing Gases

AbstractAir pollution control (APC) facilities at waste incinerator plants produce large quantities of solid residues rich in salts and heavy metals. Heavy metals are readily released to water from the residues and it has, therefore, been found suitable to apply a rapid co-precipitation/adsorption process as a means to immobilize the toxic elements. In the ‘Ferrox process’, this immobilization is based on co-precipitation with an Fe(III) oxide formed by oxidation of Fe(II) by air in an aqueous slurry with the APC residue at alkaline pH. In this work we have undertaken a Mössbauer spectroscopy study of the Fe oxide phase formed by precipitation at room temperature and of the oxides present after heating to 600 and 900°C. The only Fe oxide observed in the Ferrox product at room temperature is a very poorly crystalline ferrihydrite. Analytical transmission electron microscopy showed that the main elements associated with the ferrihydrite are Si and Ca. Following heating to 600°C the oxide is still characterized as an amorphous Fe oxide, and it is probable that Si associated with the ferrihydrite is decisive in preventing crystallization. After the 900°C treatment a transformation into defect maghemite is observed. Reducing gases produced from carbon in the samples probably induces this transformation. It eases, thus, the reduction of Fe(III) and the consequent formation of magnetite that eventually oxidizes to maghemite during cooling in air.

Time course of bronchoconstriction induced by dry gas hyperpnea in guinea pigs

1991 ◽  
Vol 70 (2) ◽  
pp. 504-510 ◽  
Author(s):  
D. W. Ray ◽  
A. Garland ◽  
C. Hernandez ◽  
S. Eappen ◽  
L. Alger ◽  
...  
Keyword(s):  
Guinea Pigs ◽  
Room Temperature ◽  
Time Course ◽  
Random Order ◽  
Quiet Breathing ◽  
Mechanically Ventilated ◽  
Abrupt Changes ◽  
Respiratory System Resistance ◽  
Humidified Air ◽  
Isocapnic Hyperpnea

We examined the effects of hyperpnea duration and abrupt changes in inspired gas heat and water content on the magnitude and time course of hyperpnea-induced bronchoconstriction (HIB) in anesthetized mechanically ventilated male Hartley guinea pigs. In 12 animals subjected to 5, 10, and 15 min (random order) of dry gas isocapnic hyperpnea [tidal volume (VT) 4-6 ml, 150 breaths/min) followed by quiet breathing of humidified air (VT 2-3 ml, 60 breaths/min), severe bronchoconstriction developed only after the cessation of hyperpnea; the magnitude of respiratory system resistance (Rrs) increased with the duration of dry gas hyperpnea [peak Rrs 1.0 +/- 0.2, 1.8 +/- 0.3, and 2.3 +/- 0.3 (SE) cmH2O.ml-1.s, respectively]. Seven other guinea pigs received, in random order, 10 min of warm humidified gas hyperpnea, 10 min of room temperature dry gas hyperpnea, and 5 min of dry gas hyperpnea immediately followed by 5 min of warm humidified gas hyperpnea. After each hyperpnea period, the animal was returned to quiet breathing of humidified gas. Rrs rose appreciably after the 10 min of dry and 5 min of dry-5 min of humidified hyperpnea challenges (peak Rrs 1.3 +/- 0.2 and 0.7 +/- 0.2 cmH2O.ml-1.s, respectively) but not after 10 min of humidified hyperpnea (0.2 +/- 0.04 cmH2O.ml-1.s). An additional five animals received 10 min of room temperature dry gas hyperpnea followed by quiet breathing of warm humidified air and 10 min of room temperature dry gas hyperpnea followed by 30 min of warm humidified gas hyperpnea in random order.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals Synthesis and Investigation of Thermo-Induced Gelation of Partially Cross-Linked Poly-2-isopropyl-2-oxazoline in Aqueous Media

Polymers ◽  
2020 ◽  
Vol 12 (3) ◽  
pp. 698 ◽  
Author(s):  
Alina Amirova ◽  
Serafim Rodchenko ◽  
Mikhail Kurlykin ◽  
Andrey Tenkovtsev ◽  
Illia Krasnou ◽  
...  
Keyword(s):  
Self Assembly ◽  
Sol Gel ◽  
Aqueous Media ◽  
Water Soluble ◽  
Thermally Induced ◽  
Thermosensitive Gel ◽  
Step Procedure ◽  
Physical Gel ◽  
Sol Gel Transition ◽  
Gel Transition

Water-soluble, partially cross-linked poly-2-isopropyl-2-oxazoline combining the properties of chemical and physical gels was synthesized by a two-step procedure. Thermally induced sol-gel transition in its aqueous solution was studied by rheology, light scattering, and turbidimetry. It was demonstrated that the synthesized product is bimodal; it consists of linear and cross-linked components. The cross-linked components are responsible for the gelation, while the linear ones abate the viscosity growth. Heating the solution above the phase transition temperature leads to the self-assembly of the particles into a physical gel. The combination of chemical and physical cross-linking was found to be a prospective route for thermosensitive gel development.

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