Magnetic resonance imaging (MRI) inherently requires considerable time for data acquisition, but obtaining multi-contrast MRI data further prolongs this process, thereby increasing susceptibility to motion artifacts. It is worth noting that the multi-contrast MR images have both structural similarities and unique contrast information. Therefore, to take advantage of their similarities while preserving their distinctive characteristics, we proposed a new method called high-dimensional subsets embedding (HDSE). This novel approach is based on the frame of low-rank modeling of local k-space neighborhoods with parallel imaging (P-LORAKS). Specifically, our approach utilizes the structural similarity of multi-contrast MR images to process different k-space data through two independent channels. In one channel, we individually separate the complementary T1-T2 k-space data and directly construct a new subset of local k-space, allowing the model to better capture structural correlations between multiple contrasts. In another channel, we provide global under-sampled T2-weighted k-space data further constrain image acquisition in high-dimensional space to maintain image consistency and reduce noise amplification. These two different channels information is fused together to form high-dimensional feature objects. Besides, we embed the constructed objects into P-LORAKS in various ways to enhance the reconstruction performance. Experimental results demonstrated that the aided reconstruction of local subsets fusion and the high-dimensional reconstruction of adaptive global constraints can improve the accuracy of image reconstruction and enhance the robustness of the model.
Physical and theoretical chemistry, Analytical chemistry
Teddy X. Cai, Nathan H. Williamson, Peter J. Basser
The field of diffusion microstructural magnetic resonance (MR) aims to probe time-dependent diffusion, i.e., an ensemble-averaged mean-squared displacement ⟨r2(t)⟩ that is not linear in time. This time-dependence contains rich information about the surrounding microenvironment. MR methods to measure time-dependent diffusion quantitatively, however, require either non-standard pulse sequences, such as oscillating gradients, or make non-physical assumptions, such as infinitely narrow gradient pulses. Here, we argue that standard spin echo and stimulated echo MR sequences can be used to probe ⟨r2(t)⟩ directly. In particular, we propose a framework in which the log-signal ratio obtained from a pair of measurements with different inter-pulse spacing Δ is proportional to the MSD between these two Δ values along the gradient direction x: ⟨rx2(Δ2)⟩−⟨rx2(Δ1)⟩. The framework is quantitative for short, finite-duration gradient pulses and under the Gaussian phase approximation (GPA). To validate the framework, we consider one-dimensional diffusion between impermeable, parallel planes, as well as periodically-spaced, permeable planes. Excellent agreement is obtained between the estimation and the ground truth in the regime where the GPA is expected to hold. Importantly, the GPA can be made to hold for any underlying microstructure, making the proposed framework widely applicable.
Physical and theoretical chemistry, Analytical chemistry
The deficiency of chemistry and physics laboratories in schools has profound implications for scientific education, as illuminated by a study conducted in Covasna County. Deprived of laboratory access, students lack the opportunity to experiment with chemical and physical phenomena, limiting the application of theoretical knowledge. This shortfall may foster a superficial understanding of the subjects and potentially dampen enthusiasm for science. Moreover, the absence of exposure to laboratory equipment and techniques stunts the cultivation of practical and critical skills crucial for scientific or technical careers, hindering students’ preparation for future pursuits in these fields.
Practical skills and a deep comprehension of scientific principles are indispensable for success in such careers. The absence of laboratory experience may place students at a disadvantage in university admissions or job competitions. It is imperative to implement viable solutions - investments in laboratory infrastructure, additional training for educators, and the development of interactive learning programs compensating for the dearth of practical experience. Integrating modern technology into the educational framework offers alternative avenues for experimentation and practical learning, mitigating the absence of physical laboratories. The study, conducted via an online questionnaire involving 61 school respondents, underscores the adverse impact of lacking chemistry and physics laboratories on students’ learning and development. However, by implementing solutions, the situation can improve, ensuring students receive comprehensive and equitable science education. Addressing this deficit is pivotal in nurturing the next generation of scientists and innovators, equipping them with the skills needed to tackle real-world challenges and contribute to scientific progress.
During the last three decades, secondary metabolites of marine origin have emerged as a significant source of bioactive compounds. Among the marine organisms explored, sponges offer a vast number of metabolites with unique structural diversity and a plethora of biological activities. Ageladine A, a fluorescent bromopyrrole alkaloid isolated from the marine sponge <i>Agelas nakamurai</i>, exhibited matrix metalloproteinase (MMP) inhibitory properties, as well as antiangiogenic activity. Due to this interesting biological profile, Ageladine A became, soon after its discovery, a target for total synthesis. In addition, a significant number of derivatives have been synthesized, and their biological activity was evaluated. The present review highlights all the successful efforts made towards the synthesis of Ageladine A. Furthermore, all the medicinal chemistry approaches to identify and assess new more potent inhibitors and to elucidate the structural features responsible for the activity are described.
Sakonsupa Damdib, Nuttamon Vanichsetakul, Phanuwat Pimpapoat
et al.
The novel and intriguing role of Fe(NO3)3 as a chemical activator in carbonization of macadamia nutshell is introduced in this work. Magnetic mesoporous carbon was achieved by chemical activation of macadamia nutshell with Fe(NO3)3 under nitrogen atmosphere at 850°C (MMC-850). Porosity of MMC-850 included SBET 317 m2/g with Vmicro 0.0796 cm3/g and considerably high Vmeso 0.4318 cm3/g. Not only did MMC-850 possesses good magnetic properties with saturation magnetization and coercive force of 31.48 emu/g and 506.6 Oe, respectively, but MMC-850 also showed high-removal efficiency of reactive black dye (RB5) with maximum adsorption capacity at 123.51 mg/g. The experimental data fit the Langmuir isotherm and Elovich model. Thermal regeneration was effective in degrading RB5 and removal ability was above 90% after two regeneration cycles. RB5 removal from water by MMC-850 as an adsorbent is considered a facile and inexpensive method since macadamia nutshell is a food by-product which is a green and renewable carbon precursor. MMC-850 is a potential adsorbent because it can be separated from wastewater treatment system using magnetic force. Besides, MMC-850 particle is not brittle compared to other porous biochar/activated carbon with similar size; therefore, it is an excellent candidate for column packing or scaling up for wastewater treatment facilities in the future.
Jun WATANABE, Masaki FURUSAWA, Kosuke NAKAMOTO
et al.
3,6-diphenyltetrazine (DPT) is an electron-deficient π-conjugated molecule with a perfectly planar structure and high crystallinity. In this study, discharge-charge tests of crystalline DPT as a cathode material for sodium ion batteries were conducted. DPT showed an initial reversible capacity of 102 mAh/g (theoretical capacity 114 mAh/g), corresponding to one electron reaction. The plateau of the discharge-charge profiles was observed at 1.9–2.1 V vs. Na/Na+. According to the ex-situ XRD, FT-IR, and XPS measurements to investigate the discharge-charge mechanism, the redox center was identified as the conjugated tetrazine ring. DPT was in a crystalline form in both the charged and discharged state and indicated the potential as a reversible Na ion host.
Prostate Specific Antigen (PSA) is a key marker for prostate cancer screening by standard laboratory tests based on blood, plasma or serum analysis. The current laboratory methods for PSA level determination are based on various chromatographic, immunochemical and other instrumental analyses that has to be done in the specialized laboratories. Experiments in this work are focused on construction of a Quartz Crystal Microbalance (QCM) biosensor as a simple device suitable for point-of-care diagnosis based on PSA concentration determination in body fluids. The QCM sensors were covered with antibody against PSA and gold nanoparticles modified with specific antibody against PSA were prepared in a separate step. Change in oscillation frequency was measured as the immunocomplexes QCM biosensor – PSA – modified gold nanoparticles were formed. Calibrating for standard solution of PSA, limit of detection equal to 0.054 μg/l and limit of quantification equal to 0.18 μg/l were figured. The biosensor was not sensitive to interference of other plasma proteins or to matrix effect and fully correlated with the Enzyme-Linked Immunosorbent Assay (ELISA) as a standard method. In a conclusion, the biosensor appears to be a simple and reliable tool that can be used in standard laboratory and point-of-care testing.
Industrial electrochemistry, Physical and theoretical chemistry
Bence Hajdusits, Marcin J Suskiewicz, Nikolas Hundt
et al.
In Gram-positive bacteria, the McsB protein arginine kinase is central to protein quality control, labeling aberrant molecules for degradation by the ClpCP protease. Despite its importance for stress response and pathogenicity, it is still elusive how the bacterial degradation labeling is regulated. Here, we delineate the mechanism how McsB targets aberrant proteins during stress conditions. Structural data reveal a self-compartmentalized kinase, in which the active sites are sequestered in a molecular cage. The ‘closed’ octamer interconverts with other oligomers in a phosphorylation-dependent manner and, unlike these ‘open’ forms, preferentially labels unfolded proteins. In vivo data show that heat-shock triggers accumulation of higher order oligomers, of which the octameric McsB is essential for surviving stress situations. The interconversion of open and closed oligomers represents a distinct regulatory mechanism of a degradation labeler, allowing the McsB kinase to adapt its potentially dangerous enzyme function to the needs of the bacterial cell.
Norazreen Zakaria, Yusairie Mohd, Lim Ying Chin
et al.
A low impedance between the microelectrode surface and brain biological tissue interface is important for a good signal quality during immunosensor recording to prevent tissue damage during electrical stimulation. The incorporation of a conducting polymer on a microelectrode surface with an internal diameter of 50 μm can significantly reduce the electrode-electrolyte (brain lysate) impedance. An impedimetric immunosensor assay was developed by exploiting the Poly ortho-phenylenediamine (PoPD) conducting properties and has been electrodeposited on the Pt/Ir microelectrode surface. The modified PoPD-Pt/Ir was further biofunctionalised with glutaraldehyde (GA) that act as a crosslinker to mouse monoclonal Aβ antibody (mAβab) immobilisation on PoPD-Pt/Ir. An immunosensor is a simpler and faster method for real-time monitoring of amyloid beta (Aβ40) based on antigen-antibody binding properties compared to the microdialysis technique in a real-time neurochemical study. This Pt/Ir-PoPD-GA- mAβab immunosensor was tested with a trace amount of Aβ40 in the brain tissue lysate sample. Nyquist plots revealed the specific binding of mAβab-amyloid beta (Aβ40) to the biofunctionalised PoPD modified microelectrode surface. Furthermore, proposed equivalent circuits were developed in conjunction with each stage of biofunctionalisation layers on modified Pt/Ir microelectrode to fit and interpret the circuit components that could further explain certain chemical processes and mechanisms of the immunosensor system such as the effect of the electrical component of PoPD film formed during fabrication and its physicochemical properties. The advantages of this needle-like immunosensor include the use of a minimal amount of protein immobilisation reagents with a highly sensitive, selective, and rapid detection technique.
Industrial electrochemistry, Physical and theoretical chemistry
The corrosion behavior, mechanical properties, and microstructural evolution of a concrete/P110 casing steel system were studied in a simulated, CO2-saturated formation water under different CO2 partial pressures. It has been found that the corrosion and mechanical properties of the cement and the cement/casing interface were affected by both cement hydration and CO2 corrosion, making the performance of the cement matrix and the interfacial transition zone improve initially and then deteriorate with time. The corrosion resistance of the casing steel reduced with increasing the immersion time and CO2 pressure. The degradation of cement and cement/casing interface was aggravated under the high CO2 pressure, which assisted the formation of a defected corrosion product layer (predominantly FexCa1-xCO3) and led to severer corrosion on the casing steel surface.
Industrial electrochemistry, Physical and theoretical chemistry
Vlachou Marilena, Siamidi Angeliki, Goula Efstratia
et al.
A variety of commonly used hydrogels were utilized in the preparation of calcium alginate beads, which incorporate the chronobiotic hormone melatonin (MLT). The in vitro release of the hormone in aqueous media at pH 1.2 and 6.8 was probed in the conjunction with the swelling of the beads and their thermal degradation properties. It has been found that the release of MLT from the beads was reversibly proportional to the extent of their expansion, which depends on the molecular mass/viscosity of the biopolymers present in the beads; the higher the molecular mass/viscosity of the hydrogels the greater the beads swelling and the less the MLT’s release. Thermogravimetric analysis (TGA) data support the presence of the components in the hybrid hydrogel beads and elucidate their effects on the thermal stability of the systems. Thus, the physicochemical properties of the biopolymers used, along with their stereoelectronic features modulate the release of MLT from the beads, providing formulations able to treat sleep onset related problems or dysfunctions arising from poor sleep maintenance.
Microbial extracellular electron transfer (EET) in diverse environments has gained increasing attention. However, the EET capability of oral pathogens and associated mechanisms has been scarcely studied. Here, our results suggest that the Capnocytophaga ochracea, an etiological human pathogen showed current production and demonstrated a rate enhancement of electron transport at a high cell-density. C. ochracea produced ∼10-fold more current at an OD600 of 0.5 associated with twice a higher glucose consumption rate per cell, compared to 0.1, measured in a three-electrode electrochemical system by single-potential amperometry at +0.2 V (vs Ag/AgCl [sat. KCl]). During current production, the accumulation of the redox molecules on the electrode was observed at high OD600 compared to low OD600. Apart from cell released redox active product, externally added redox active additives enhanced the electron transport, suggesting the EET capability of C. ochracea via electron mediator. A higher metabolic activity via single-cell assay (based on anabolic incorporation of 15NH4+) in cells that did not attach to the electrode strongly suggests the EET rate enhancement through an electron mediator. As bacterial populations play a role in the pathogenesis of human infections such as periodontitis, our results suggest that population-induced EET mechanisms may facilitate in-vivo colonization of C. ochracea.
In this work, [EMIM]F-urea-H2O system is capable of dissolving Cu2O, and then the metallic copper was electrodeposited from this system at room temperature. The reduction of Cu (I) in this system involves a quasi-reversible and one-step single-electron transfer process. The electrodeposition of copper was performed on a tungsten (W) substrate at −0.67 V (vs. Ag) and 353 K via potentiostatic electrolysis. The electrodeposits were identified as metallic copper, as verified by XRD and EDS. SEM image shows that uniform, polygonal nanoparticles of copper were obtained after the potentiostatic static electrolysis.