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1.
Angew Chem Int Ed Engl ; : e202405307, 2024 Jun 14.
Artigo em Inglês | MEDLINE | ID: mdl-38874082

RESUMO

Metal-organic framework (MOF) glasses, known for their potential in gas separation, optics, and solid-state electrolytes, benefit from the processability of their (supercooled) liquid state. Traditionally, MOF glasses are produced by heating MOF crystals to their melting point and then cooling the liquid MOF to room temperature under an inert atmosphere. While effective, this melt-quenching technique requires high energy due to the high temperatures involved. It also limits the scope of new material development by restricting the compositional range to only those combinations of metal ions and linkers that are highly thermally stable. An alternative, mechanical milling at room temperature, has demonstrated its capability to transform MOF crystals into amorphous phases. However, the specific conditions under which these amorphous phases exhibit glass-like behavior remain uncharted. In this study, we explore the mechanochemical amorphization and vitrification of a variety of zeolitic imidazolate frameworks (ZIFs) with diverse linkers and different metal ions (Zn2+, Co2+ and Cu2+) at room temperature. Our findings demonstrate that ZIFs capable of melting can be successfully converted into glasses through ball-milling. Remarkably, some non-meltable ZIFs can also be vitrified using the ball-milling technique, as highlighted by the preparation of the first Cu2+-based ZIF glass.

2.
Nano Lett ; 22(23): 9372-9379, 2022 12 14.
Artigo em Inglês | MEDLINE | ID: mdl-36441580

RESUMO

We investigated a mechanism of crystal melting and crystallization behavior of a two-dimensional coordination polymer [Ag2(L1)(CF3SO3)2] (1, L1 = 4,4'-biphenyldicarbonitrile) upon heating-cooling processes. The crystal showed melting at 282 °C, and the following gentle cooling induced the abrupt crystallization at 242 °C confirmed by DSC. A temperature-dependent structural change has been discussed through calorimetric, spectroscopic, and mechanical measurements. They indicated that the coordination-bond networks are partially retained in the melt state, but the melt showed a significantly low viscosity of 9.8 × 10-2 Pa·s at Tm which is six orders lower than that of ZIF-62 at Tm (435 °C). Rheological studies provided an understanding of the fast relaxation dynamics for the recrystallization process, along with that the high Tm provides enough thermal energy to crossover the activation energy barrier for the nucleation. The isothermal crystallization kinetics through calorimetric measurements with applying the Avrami equation identified the nature of the nuclei and its crystal growth mechanism.


Assuntos
Polímeros , Cristalização , Cinética , Polímeros/química , Varredura Diferencial de Calorimetria , Transição de Fase
3.
Environ Monit Assess ; 195(10): 1158, 2023 Sep 06.
Artigo em Inglês | MEDLINE | ID: mdl-37673826

RESUMO

Identifying groundwater contamination sources and supervising groundwater quality conditions are urgently needed to protect the groundwater resources of coastal areas like Contai of India, as communities here are heavily relying on groundwater which deteriorates progressively. So current research aims to address in detail about origins and influencing factors of groundwater contamination, status, and monitoring water quality by employing extremely useful leading technologies like principal component and factor analyses (PCA/FA), groundwater quality index (GWQI), and multiple linear regression (MLR) that helps to simplify complicated works instead of the conventional methods. Eight groundwater quality parameters were evaluated here, such as pH, TH (total hardness), Tur (turbidity), EC (electrical conductivity), TDS (total dissolved solids), Mn (manganese), Fe (iron), and Cl (chloride) for 38 sites. Three principal components with ~ 81% of the total variance were extracted from the PCA/FA analysis. The origin of maximum loadings of each factor is identified as a result of saline water, disintegration and leaching process, organic or else biogenic activities, and lithogenic or otherwise non-lithogenic links through percolating water. GWQI results show that ~ 87% of the samples fall into the good category and ~ 13% of the samples fall into the poor to very poor category. A model consisting of Tur, Fe, EC, Mn, TH, and Cl as independent parameters is more feasible and is proposed to predict GWQI obtained from MLR analysis. This MLR model also suggests that turbidity with the highest beta coefficient (0.820) is a key contributor relative to the entire groundwater class in this affected area. The findings relating to this research may support the designer and officials in monitoring and protecting coastal groundwater resources like selected areas.


Assuntos
Monitoramento Ambiental , Água Subterrânea , Modelos Lineares , Análise de Componente Principal , Cloretos , Índia , Ferro
4.
Phys Chem Chem Phys ; 24(2): 982-994, 2022 Jan 04.
Artigo em Inglês | MEDLINE | ID: mdl-34918013

RESUMO

The thermal spin transition and the photo-induced high-spin → low-spin relaxation of the prototypical [Fe(ptz)6](BF4)2 spin-crossover compound (ptz = 1-propyltetrazole) diluted in the isostructural ruthenium host lattice [Ru(ptz)6](BF4)2, which stabilizes the Fe(II) low-spin state, have been investigated. We demonstrate the presence of a crystallographic phase transition around 145 K (i.e. from the high-temperature ordered high-spin phase to a low-temperature disordered low-spin phase) upon slow cooling from room temperature. This crystallographic phase transition is decoupled from the thermal spin transition. A supercooled ordered low-spin phase is observed as in the pure Fe(II) analogue upon fast cooling. A similar order-disorder phase transition is also observed for pure [Ru(ptz)6](BF4)2 but at relatively higher temperature (i.e. at around 150 K) without involving any spin transition. For Ru-diluted [Fe(ptz)6]2+, the crystallographic phase transition as well as strong cooperative effects involving various degrees of elastic frustration are at the origin of stepped sigmoidal high-spin → low-spin relaxation curves, which are modelled in the framework of a classical mean field model, considering both the tunnelling and thermally activated regimes. Optical microscopy studies performed on two different single crystals showed the existence of hysteretic thermal transitions with slight domain formation, hardly visible in the static crystal images. This behavior is attributed to the double effect upon Ru dilution, which decreases the cooperative character of the transition and simultaneously reduces the optical contrast between the LS and HS states. Moreover, the transition temperature revealed to be slightly crystal dependent, highlighting the crucial role of the spatial distribution of Ru from one crystal to another, in addition to the well-known effects of crystal shape and size.

5.
Angew Chem Int Ed Engl ; 61(14): e202117261, 2022 Mar 28.
Artigo em Inglês | MEDLINE | ID: mdl-35104379

RESUMO

The discovery of a universal memory that exhibits fast access speed, high-density storage, and non-volatility has fuelled research into phase-change materials over the past decades. In spite of the efficiency of the inorganic chalcogenides for phase-change random access memory (PCRAM), they still have some inherent drawbacks, such as high temperature required for phase change and difficulty to control the domain size of the phase change, because of their brittleness. Here we present a AuI -thiolate coordination polymer which undergoes two successive phase changes on application of mild heating (<200 °C) from amorphous-to-crystalline1-to-crystalline2 phases. These transitions are reversible upon soft hand grinding. More importantly, each phase exhibits different photoluminescent properties for an efficient optical read-out. We believe that the ability of the AuI -thiolate coordination polymer to have reversible phase changes under soft conditions and at the same time to display distinct optical signals, can pave the way for the next generation of PCRAM.

6.
Faraday Discuss ; 225: 403-413, 2021 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-33103691

RESUMO

A three-dimensional (3D) metal-organic framework [Ag(pL2)(CF3SO3)]·2C6H6 (pL2 = 1,3,5-tris(4-cyanophenylethynyl)benzene), composed of Ag+ and tripodal nitrile ligands, was prepared to enable the investigation of its crystal melting and vitrification behaviors. The guest-free state showed a crystal melting at 271 °C, and the liquid state transformed into a glassy state via cooling. The vitrification of the crystalline compound into an amorphous glassy state was also obtained by mechanical hand-grinding. The structure of the glassy state retained the 3D networked structure, confirmed by FT-IR, X-ray absorption, and scattering measurements. The mechanically induced glass showed a small uptake of CO2 and a strong affinity for benzene and H2O vapors, confirmed by gas sorption isotherms. Powder X-ray diffraction studies have revealed that the vitrified structure returned to the original 3D crystalline structure by exposure to these vapors.

7.
Nat Mater ; 22(7): 809-810, 2023 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-37169975

Assuntos
Fumaça
8.
Inorg Chem ; 58(9): 6257-6267, 2019 May 06.
Artigo em Inglês | MEDLINE | ID: mdl-31009214

RESUMO

The reaction of [Ni(COD)2] (COD; cyclooctadiene) in THF with the NNN-pincer ligand bis(imino)pyridyl (L1) reveals a susceptibility to oxidation in an inert atmosphere ([O2] level <0.5 ppm), resulting in a transient Ni:dioxygen adduct. This reactive intermediate abstracts a hydrogen atom from THF and stabilizes an uncommon Ni(III) complex. The complex is crystallographically characterized by a molecular formula of [NiIII(L1··)2-(OH)] (1). Various isotopically labeled experiments (16O/18O) assertively endorse the origin of terminal oxygen based ligand in 1 due to the activation of molecular dioxygen. The presence of proton bound to the terminal oxygen in 1 is well supported by NMR, IR spectroscopy, DFT calculations, and hydrogen atom transfer (HAT) reactions promoted by 1. The observation of shakeup satellite peaks for the primary photoelectron lines of Ni(2p) in the X-ray photoelectron spectroscopy (XPS) unambiguously confirms the paramagnetic signature associated with the distorted square planar nickel ion, which is consistent with the trivalent oxidation state assigned for the nickel ion in 1. The variable temperature magnetic susceptibility data of 1 shows dominant antiferromagnetic interactions exist among the paramagnetic centers, resulting in an overall S = 1/2 ground state. Variable temperature X-band EPR studies performed on 1 show evidence for the S = 1/2 ground state, which is consistent with magnetic data. The unusual g-tensor extracted for the ground state S = 1/2 is analyzed under a strong exchange limit of spin-coupled centers. The electronic structure predicted for 1 is in good agreement with theoretical calculations.

9.
Inorg Chem ; 57(15): 9002-9011, 2018 Aug 06.
Artigo em Inglês | MEDLINE | ID: mdl-30010328

RESUMO

Controlling quantum tunneling of magnetization (QTM) is a persistent challenge in lanthanide-based single-molecule magnets. As the exchange interaction is one of the key factors in controlling the QTM, we targeted lanthanide complexes with an increased number of radicals around the lanthanide ion. On the basis of our targeted approach, a family of pseudo-octahedral lanthanide/transition-metal complexes were isolated with the general molecular formula of [M(L•-)3] (M = Gd (1), Dy (2), Er (3), Y (4)) using the redox-active iminopyridyl (L•-) ligand exclusively, which possess the highest ratio of radicals to lanthanide reported for discrete metal complexes. Direct current magnetic susceptibility studies suggest that dominant antiferromagnetic interactions exist between the radical and lanthanide ions in all of the complexes, which is strongly corroborated by magnetic data fitting using a Heisenberg-Dirac-Van Vleck (HDVV) Hamiltonian (-2 J Hamiltonian). A good agreement between the fit and the experimental magnetic data obtained using g = 2, Jrad-rad = -111.9 cm-1 for 4 and g = 1.99, Jrad-rad = -111.9 cm-1, JGd-rad = -1.85 cm-1 for 1. Complex 2 shows frequency-dependent slow magnetization relaxation dynamics in the absence of an external magnetic field, while 3 shows field-induced frequency-dependent χM'' signals. An ideal octahedral geometry around the lanthanide ion is predicted to be unsuitable for the design of a single-molecule magnet (SMM); nevertheless, complex 2 exhibits slow relaxation of magnetization with a record high anisotropy barrier for a six-coordinate Dy(III) complex. A rationale for this unusual behavior is detailed and reveals the strength of the synthetic methodology developed.

10.
Inorg Chem ; 57(11): 6584-6598, 2018 Jun 04.
Artigo em Inglês | MEDLINE | ID: mdl-29767530

RESUMO

Two lanthanide-containing structurally analogous porous coordination polymers (PCPs) have been isolated with the general molecular formula [Ln2(L1)2(H2O)4(ox)] n.4 nH2O (where L1 = fumarate, ox = oxalate; Ln = Dy (1), Gd (2)). Thermogravimetric analysis (TGA) and TG-MS measurements performed on 1 and 2 suggest that not only the solvated water molecules in the crystal lattice but also the four coordinated water molecules on the respective lanthanides in 1 and 2 are removed upon activation. Due to the removal of the waters, 1 and 2 lost their crystallinity and became amorphous, as confirmed by powder X-ray diffraction (PXRD). We propose the molecular formula [Ln2(L1)2(ox)] n for the amorphous phase of 1 and 2 (where Ln = Dy (1'), Gd (2')) on the basis of XANES, EXAFS, and other experimental investigations. Magnetization relaxation dynamics probed on 1 and 1' reveal two different relaxation processes with effective energy barriers of 53.5 and 7.0 cm-1 for 1 and 45.1 and 6.4 cm-1 for 1', which have been rationalized by detailed ab initio calculations. For the isotropic lanthanide complexes 2 and 2', magnetocaloric effect (MCE) efficiency was estimated through detailed magnetization measurements. We have estimated -Δ S m values of 52.48 and 41.62 J kg1- K-1 for 2' and 2, respectively, which are one of the largest values reported for an extended structure. In addition, a 26% increase in -Δ Sm value in 2' in comparison to 2 is achieved by simply removing the passively contributing (for MCE) solvated water molecule in the lattice and coordinated water molecules.

11.
Inorg Chem ; 57(23): 14967-14982, 2018 Dec 03.
Artigo em Inglês | MEDLINE | ID: mdl-30418745

RESUMO

Three structurally analogous hexanuclear ruthenium(III) complexes were isolated with the general molecular formula of [Ru6III(O)2(µ4-η2-η2-CH2O2)( t-BuCO2)12(L)2] where L = pyridine (1) or 4-dimethylamino pyridine (DMAP; 2) or 4-cyanopyridine (3). Complexes 1 and 3 were solved in the tetragonal I4̅c2 and P41212 space group, respectively, while 2 crystallized in the monoclinic system with P21 /c space group. In all three complexes, two oxo-centered Ru(III) triangles were bridged by a unique and a rare methylenediolate (CH2O2)2-) ligand. This (CH2O2)2- group is reported to be an intermediate, which is not isolated in its metal-free form, to date, as it is unstable. Control experiments performed evidently reveal that the unique reaction condition followed is mandatory to isolate 1-3 and the origin of (CH2O2)2- is unknown at the moment, as no precursor was used to form this intermediate. The presence of (CH2O2)2- identified through X-ray diffraction was further unambiguously confirmed by various 1D (1H and 13C) and 2D-NMR (HSQC, TOCSY, NOESY, and DEPT) spectroscopies. Direct current (dc) magnetic susceptibility measurements performed on 1 and 2 reveal the predominant antiferromagnetic exchange interaction between the Ru(III) centers result in a diamagnetic ground state at 2.0 K. The paramagnetic influence of 1-3 at room temperature evidently felt by the 1H nuclei of the (CH2O2)2- unit predominates compared to other NMR active nuclei in the complexes. The presence of an electron donating or withdrawing substituent on the terminal pyridine results in significant change in the dihedral angle of two oxo-centered triangular (Ru3O-) planes. The change in the structural parameters of 1-3 due to the substituents markedly reflected on the absorption profile and redox behavior, which are systematically investigated. Preliminary galvanostatic charge/discharge cycling experiments performed on a representative complex (3) suggest that 3 can be a promising candidate to employ as an effective multiple electron charge carrier in a nonaqueous redox flow battery.

12.
Chemistry ; 23(20): 4903-4916, 2017 Apr 06.
Artigo em Inglês | MEDLINE | ID: mdl-28177539

RESUMO

Four complexes containing DyIII and PrIII ions and their LnIII -ZnII analogs have been synthesized in order to study the influence that a diamagnetic ZnII ion has on the electronic structure and hence, the magnetic properties of the DyIII and PrIII single ions. Single-crystal X-ray diffraction revealed the molecular structures as [DyIII (HL)2 (NO3 )3 ] (1), [PrIII (HL)2 (NO3 )3 ] (2), [ZnII DyIII (L)2 (CH3 CO2 )(NO3 )2 ] (3) and [ZnII2 PrIII (L)2 (CH3 CO2 )4 (NO3 )] (4) (where HL=2-methoxy-6-[(E)-phenyliminomethyl]phenol). The dc and ac magnetic data were collected for all four complexes. Compounds 1 and 3 display frequency dependent out-of-phase susceptibility signals (χM "), which is a characteristic signature for a single-molecule magnet (SMM). Although 1 and 3 are chemically similar, a fivefold increase in the anisotropic barrier (Ueff ) is observed experimentally for 3 (83 cm-1 ), compared to 1 (16 cm-1 ). To rationalize the larger anisotropic barrier (1 vs. 3), detailed ab initio calculations were performed. Although the ground state Kramer's doublet in both 1 and 3 are axial in nature (gzz =19.443 for 1 and 18.82 for 3), a significant difference in the energy gap (Ueff ) between the ground and first excited Kramer's doublet is calculated. This energy gap is governed by the electrostatic repulsion between the DyIII ion and the additional charge density found for the phenoxo bridging ligand in 3. This extra charge density was found to be a consequence of the presence of the diamagnetic ZnII ion present in the complex. To explore the influence of diamagnetic ions on the magnetic properties further, previously reported and structurally related Zn-DyIII complexes were analyzed. These structurally analogous complexes unambiguously suggest that the electrostatic repulsion is found to be maximal when the Zn-O-Dy-O dihedral angle is small, which is an ideal condition to maximize the anisotropic barrier in DyIII complexes.

13.
Inorg Chem ; 56(22): 14260-14276, 2017 Nov 20.
Artigo em Inglês | MEDLINE | ID: mdl-29087710

RESUMO

A series of monomeric lanthanide Schiff base complexes with the molecular formulas [Ce(HL)3(NO3)3] (1) and [Ln(HL)2(NO3)3], where LnIII = Tb (2), Ho (3), Er (4), and Lu (5), were isolated and characterized by single-crystal X-ray diffraction (XRD). Single-crystal XRD reveals that, except for 1, all complexes possess two crystallographically distinct molecules within the unit cell. Both of these crystallographically distinct molecules possess the same molecular formula, but the orientation of the coordinating ligand distinctly differs from those in complexes 2-5. Alternating-current magnetic susceptibility measurement reveals that complexes 1-3 exhibit slow relaxation of magnetization in the presence of an optimum external magnetic field. In contrast to 1-3, complex 4 shows a blockade of magnetization in the absence of an external magnetic field, a signature characteristic of a single-ion magnet (SIM). The distinct magnetic behavior observed in 4 compared to other complexes is correlated to the suitable ligand field around a prolate ErIII ion. Although the ligand field stabilizes an easy axis of anisotropy, quantum tunnelling of magnetization (QTM) is still predominant in 4 because of the low symmetry of the complex. The combination of low symmetry and an unsuitable ligand-field environment in complexes 1-3 triggers faster magnetization relaxation; hence, these complexes exhibit field-induced SIM behavior. In order to understand the electronic structures of complexes 1-4 and the distinct magnetic behavior observed, ab initio calculations were performed. Using the crystal structure of the complexes, magnetic susceptibility data were computed for all of the complexes. The computed susceptibility and magnetization are in good agreement with the experimental magnetic data [χMT(T) and M(H)] and this offers confidence on the reliability of the extracted parameters. A tentative mechanism of magnetization relaxation observed in these complexes is also discussed in detail.

15.
Chemistry ; 21(44): 15639-50, 2015 Oct 26.
Artigo em Inglês | MEDLINE | ID: mdl-26383786

RESUMO

Three cationic [Ln4 ] squares (Ln=lanthanide) were isolated as single crystals and their structures solved as [Dy4 (µ4 -OH)(HL)(H2 L)3 (H2 O)4 ]Cl2 ⋅(CH3 OH)4 ⋅(H2 O)8 (1), [Tb4 (µ4 -OH)(HL)(H2 L)3 (MeOH)4 ]Cl2 ⋅(CH3 OH)4 ⋅(H2 O)4 (2) and [Gd4 (µ4 -OH)(HL)(H2 L)3 (H2 O)2 (MeOH)2 ]Br2 ⋅(CH3 OH)4 ⋅(H2 O)3 (3). The structures are described as hydroxo-centered squares of lanthanide ions, with each edge of the square bridged by a doubly deprotonated H2 L(2-) ligand. Alternating current magnetic susceptibility measurements show frequency-dependent out-of-phase signals with two different thermally assisted relaxation processes for 1, whereas no maxima in χM " appears above 2.0 K for complex 2. For 1, the estimated effective energy barrier for these two relaxation processes is 29 and 100 K. Detailed ab initio studies reveal that complex 1 possesses a toroidal magnetic moment. The ab initio calculated anisotropies of the metal ions in complex 1 were employed to simulate the magnetic susceptibility by using the Lines model (POLY_ANISO) and this procedure yields J1 =+0.01 and J2 =-0.01 cm(-1) for 1 as the two distinct exchange interactions between the Dy(III) ions. Similar parameters are also obtained for complex 1 (and 2) from specific heat measurements. A very weak antiferromagnetic super-exchange interaction (J1 =-0.043 cm(-1) and g=1.99) is observed between the metal centers in 3. The magnetocaloric effect (MCE) was estimated by using field-dependent magnetization and temperature-dependent heat-capacity measurements. An excellent agreement is found for the -ΔSm values extracted from these two measurements for all three complexes. As expected, 3 shows the largest -ΔSm variation (23 J Kg(-1) K(-1) ) among the three complexes. The negligible magnetic anisotropy of Gd indeed ensures near degeneracy in the (2S+1) ground state microstates, and the weak super-exchange interaction facilitates dense population of low-lying excited states, all of which are likely to contribute to the MCE, making complex 3 an attractive candidate for cryogenic refrigeration.

16.
Chemistry ; 20(44): 14235-9, 2014 Oct 27.
Artigo em Inglês | MEDLINE | ID: mdl-25214152

RESUMO

Four isostructural [Ni2 Ln2 (CH3 CO2 )3 (HL)4 (H2 O)2 ](3+) (Ln(3+) =Dy (1), Tb (2), Ho (3) or Lu (4)) complexes and a dinuclear [NiGd(HL)2 (NO3 )3 ] (5) complex are reported (where HL=2-methoxy-6-[(E)-2'-hydroxymethyl-phenyliminomethyl]-phenolate). For compounds 1-3 and 5, the Ni(2+) ions are ferromagnetically coupled to the respective lanthanide ions. The ferromagnetic coupling in 1 suppresses the quantum tunnelling of magnetisation (QTM), resulting in a rare zero dc field Ni-Dy single-molecule magnet, with an anisotropy barrier Ueff of 19 K.

17.
Environ Sci Pollut Res Int ; 31(13): 19439-19457, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-38355860

RESUMO

The water quality index (WQI) is a globally accepted guideline to indicate the water quality standard of any groundwater resource. Water levels in existing groundwater sources are declining in several coastal zones. Therefore, for monitoring water quality and improving water management, the prediction and identification of groundwater status by an effective technique with higher accuracy is urgently needed. Therefore, this research aims to find an effective model for WQI prediction by comparing entropy and critic weight-based WQI (ENW-WQI and CRITIC-WQI) with multi-layer perceptron artificial neural network (MLP-ANN) technique and also to identify contaminated zones using GIS. Initially, 1000 water sampling datasets with concentrations of several water quality parameters of different coastal blocks of eastern India during 2018 to 2022 are considered for the estimation of ENW-WQI and CRITIC-WQI. It shows 65% and 67% of the samples are excellent to good for drinking. ENW-WQI and CRITIC-WQI-based MLP-ANN models have been established considering different data portioning and hidden neuron numbers. Input variables and appropriate dataset partitioning with hidden neurons for models obtained from correlation and trial-error analysis. Spatial distribution maps are also produced for calculated WQIs using inverse distance weighted interpolation approaches. Three fitting models are obtained: ENW-WQI-MLP-ANN, CRITIC-WQI-MLP-ANN-I and CRITIC-WQI-MLP-ANN-II. CRITIC-WQI-MLP-ANN-II model (data ratio 85:15, network structure 6-12-1, R2 = 0.986, NSE = 0.98, and error rate 0.49%) provides the best accuracy in WQI prediction. The GIS-based WQI maps record several areas related to drinking water quality. The results of this research can help in planning the provision of safe drinking water in the future.


Assuntos
Água Potável , Água Subterrânea , Poluentes Químicos da Água , Qualidade da Água , Monitoramento Ambiental/métodos , Água Potável/análise , Água Subterrânea/química , Aprendizado de Máquina , Poluentes Químicos da Água/análise
18.
3D Print Addit Manuf ; 11(1): 347-362, 2024 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-38389691

RESUMO

The wide development in biomedical, regenerative medicine, and surgical techniques has ensured that new technologies are developed to improve patient-specific treatment and care. Tissue engineering is a special field in biomedical engineering that works toward cell development using scaffolds. Bone tissue engineering is a separate branch of tissue engineering, in which the construction of bone, functionalities of bone, and bone tissue regeneration are studied in detail to repair or regenerate new functional bone tissues. In India alone, people suffering from bone diseases are extensive in numbers. Almost 15% to 20% of the population suffers from osteoporosis. Bone scaffolds are proving to be an excellent solution for osseous abnormalities or defect treatment. Scaffolds are three dimensional (3D) and mostly porous structures created to enhance new tissue growth. Bone scaffolds are specially designed to promote osteoinductive cell growth, expansion, and migration on their surface. This review article aims to provide an overview of possible bone scaffolding materials in practice, different 3D techniques to fabricate these scaffolds, and effective bone scaffold characteristics targeted by researchers to fabricate tissue-engineered bone scaffolds.

19.
Chem Sci ; 15(19): 7198-7205, 2024 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-38756817

RESUMO

Hybrid organic-inorganic perovskites (HOIPs) occupy a prominent position in the field of materials chemistry due to their attractive optoelectronic properties. While extensive work has been done on the crystalline materials over the past decades, the newly reported glasses formed from HOIPs open up a new avenue for perovskite research with their unique structures and functionalities. Melt-quenching is the predominant route to glass formation; however, the absence of a stable liquid state prior to thermal decomposition precludes this method for most HOIPs. In this work, we describe the first mechanochemically-induced crystal-glass transformation of HOIPs as a rapid, green and efficient approach for producing glasses. The amorphous phase was formed from the crystalline phase within 10 minutes of ball-milling, and exhibited glass transition behaviour as evidenced by thermal analysis techniques. Time-resolved in situ ball-milling with synchrotron powder diffraction was employed to study the microstructural evolution of amorphisation, which showed that the crystallite size reaches a comminution limit before the amorphisation process is complete, indicating that energy may be further accumulated as crystal defects. Total scattering experiments revealed the limited short-range order of amorphous HOIPs, and their optical properties were studied by ultraviolet-visible (UV-vis) spectroscopy and photoluminescence (PL) spectroscopy.

20.
Indian J Orthop ; 57(Suppl 1): 33-41, 2023 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-38107805

RESUMO

Osteoporosis and sarcopenia are major health issues which are going to have a significant impact in an aging global population. Osteoporosis, which reduces bone density and increases fracture risk, and sarcopenia, which causes muscle loss and strength loss, have a complicated risk profile with consequences that go beyond bone and muscle health. This chapter illuminates the complex link between osteoporosis and sarcopenia, including overlapping causes, clinical consequences, and new treatments. This chapter covers bone and muscle biology, age-related changes that cause osteoporosis and sarcopenia, and the importance of physical exercise and diet in their prevention and management. It also discusses clinical evaluation methods, risk assessment and diagnostic criteria for early diagnosis and intervention. Novel therapies and continuing research in the management of osteoporosis and sarcopenia are also discussed. Medications, exercise, and nutrition can promote bone and muscle health. This chapter aims to explore the recent concepts by elucidating the complex relationship between osteoporosis and sarcopenia and advocating for integrated care paradigms.

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