Search Results (5)

In this study, the efficiency of functionalized bentonite (F-bentonite) and NiAl-layered double hydroxide (LDH), as well as their nanocomposites, was explored regarding the adsorption of cadmium ions (Cd²⁺) in batch tests. Surface characterization using SEM, EDX, and FTIR analyses confirmed the successful loading of LDH (NiAl) onto the F-bentonite and the adsorption of Cd²⁺ onto the F-bentonite, LDH (NiAl), and LDH/F-bentonite composite adsorbent, suggesting ion exchange and surface precipitation as the main controlling mechanisms of the formation of adsorbent. An equilibrium contact period of 60 min was suggested, with the LDH/F-bentonite composite presenting the highest adsorption capacity and removal effectiveness as compared to the other adsorbents. The LDH/F-bentonite composite also presented the highest removal efficiency and maximum adsorption capacity at an optimum pH value of 7.0. A steady increase in the uptake capacity of Cd²⁺ was observed by increasing the dosage of the adsorbents, with the LDH/F-bentonite composite having the best adsorption capacity. The fitting of the pseudo second-order kinetic model to the adsorption data of Cd²⁺ suggested chemisorption on the adsorbents’ surfaces as the controlling mechanism. The Langmuir isotherm with a near-perfect fitting revealed a monolayer adsorption, while physical adsorption of Cd²⁺ onto all the adsorbents is proposed using the D–R isotherm. Finally, both homogeneous and heterogeneous adsorption systems are proposed for all the adsorbents due to the satisfactory fitting of the Sips and R–P isotherm models. Full article

Heat-affected zones (HAZs) in real welds are usually quite narrow, and consequently most standard mechanical tests are difficult or even impossible. Therefore, simulated microstructures are often used for mechanical tests. However, the most often used weld thermal cycle simulator produces only a few millimeters wide area of simulated microstructure in the middle of specimens. Consequently, these kind of simulated specimen are not suitable for standard tensile tests, and even for Charpy impact tests, the simulated area can be too narrow. Therefore, to investigate the mechanical properties of a fine-grain heat-affected zone in 18CrNiMo7-6 steel, two methods were used for simulation of as-welded microstructures: (a) a weld thermal cycle simulator, and (b) as an alternative, though not yet verified option, austenitizing in a laboratory furnace + water quenching. The microstructures were compared and mechanical properties investigated. The grain sizes of the simulated specimens were 10.9 μm (water-quenched) and 12.6 μm (simulator), whereby the deviations from the real weld were less than 10%. Both types of simulated specimen were used for hardness measurement, Charpy impact tests, and fatigue tests. Water-quenched specimens were large enough to enable standard tensile testing. A hardness of 425 HV, yield strength R_p02 = 1121 MPa, tensile strength R_m = 1475 MPa, impact energy KV = 73.11 J, and crack propagation threshold ΔK_thR = 4.33 MPa m^0.5 were obtained with the water quenched specimens, and 419 HV, KV = 101.49 J, and ΔK_thR = 3.4 MPa m^0.5 with the specimens prepared with the simulator. Comparison of the results confirmed that the annealed and quenched specimens were suitable for mechanical tests of FG HAZs, even for standard tensile tests. Due to the use of simulated test specimens, the mechanical properties determined can be linked to the FG HAZ microstructure in 18CrNiMo7-6 steel. Full article

In patients treated for prostate cancer (PCa) with radical prostatectomy (RP), determining the risk of extraprostatic extension (EPE) and nodal involvement (NI) remains crucial for planning nerve-sparing and extended lymphadenectomy. The study aimed to determine proteins that could serve as immunohistochemical markers of locally advanced PCa. To select candidate proteins associated with adverse pathologic features (APF) reverse-phase protein array data of 498 patients was retrieved from The Cancer Genome Atlas. The analysis yielded 6 proteins which were then validated as predictors of APF utilizing immunohistochemistry in a randomly selected retrospective cohort of 53 patients. For univariate and multivariate analysis, logistic regression was used. Positive expression of TfR1 (OR 13.74; p = 0.015), reduced expression of CD49b (OR 10.15; p = 0.013), and PSA (OR 1.29; p = 0.013) constituted independent predictors of EPE, whereas reduced expression of e-cadherin (OR 10.22; p = 0.005), reduced expression of CD49b (OR 24.44; p = 0.017), and PSA (OR 1.18; p = 0.002) were independently associated with NI. Both models achieved high discrimination (AUROC 0.879 and 0.888, respectively). Immunohistochemistry constitutes a straightforward tool that might be easily utilized before RP. Expression of TfR1 and CD49b is associated with EPE, whereas expression of e-cadherin and CD49b is associated with NI. Since following immunohistochemical markers predicts respective APFs independently from PSA, in the future they might supplement existing preoperative nomograms or be implemented in novel tools. Full article

The envelope removal method has the advantage of suppressing the background spectrum and expanding the weak absorption characteristic information. However, for second-class water bodies with a relatively complex water quality, there are few studies on the inversion of chlorophyll a ($Chl\text{-}\mathrm{a}$) concentration in water bodies that consider the spectral absorption characteristics. In addition, the current research on the inversion of the $Chl\text{-}\mathrm{a}$ concentration was carried out under the condition of sample concentration equilibrium. For areas with a highly variable $Chl\text{-}\mathrm{a}$ concentration, it is still challenging to establish a highly applicable and accurate $Chl\text{-}\mathrm{a}$ concentration inversion model. Taking Dongting Lake in China as an example, this study used high-concentration samples and spectral absorption characteristics to invert the $Chl\text{-}\mathrm{a}$ concentration. The decap method was used to preprocess the high-concentration samples with large deviations, and the envelope removal method was used to extract the spectral absorption characteristic parameters of the water body. On the basis of the correlation analysis between the water $Chl\text{-}\mathrm{a}$ concentration and the spectral absorption characteristics, the water $Chl\text{-}\mathrm{a}$ concentration was inverted. The results showed the following: (1) The bands that were significantly related to the $Chl\text{-}\mathrm{a}$ concentration and had a large correlation coefficient were mainly located in the three absorption valleys (400–580, 580–650, and 650–710 nm) of the envelope removal curve. Moreover, the correlation between the $Chl\text{-}\mathrm{a}$ concentration and the absorption characteristic parameters at 650–710 nm was better than that at 400–580 nm and 580–650 nm. (2) Compared with the conventional inversion model, the uncapped inversion model had a higher R_P² and a lower RMSE_P, and was closer to the predicted value of the 1:1 line. Moreover, the performance of the uncapped inversion model was better than that of the conventional inversion model, indicating that the uncapped method is an effective preprocessing method for high-concentration samples with large deviations. (3) The predictive capabilities of the ER_New model were significantly better than those of the R_New model. This shows that the envelope removal method can significantly amplify the absorption characteristics of the original spectrum, which can significantly improve the performance of the prediction model. (4) From the inversion models for the absorption characteristic parameters, the prediction models of A_{650–710 nm}_New and D_{650–710 nm}_New exhibited the best performance. The three combined models (A_{650–710 nm}&D_{650–710 nm}_New, A_{650–710 nm}&NI_New, A_{650–710 nm}&DI_New) also demonstrated good predictive capabilities. This demonstrates the feasibility of using the spectral absorption feature to retrieve the chlorophyll concentration. Full article

Copper-containing nitrite reductases (CuNiRs) play a key role in the global nitrogen cycle by reducing nitrite (NO₂⁻) to nitric oxide, a reaction that involves one electron and two protons. In typical two-domain CuNiRs, the electron is acquired from an external electron-donating partner. The recently characterised Rastonia picketti (RpNiR) system is a three-domain CuNiR, where the cupredoxin domain is tethered to a heme c domain that can function as the electron donor. The nitrite reduction starts with the binding of NO₂⁻ to the T2Cu centre, but very little is known about how NO₂⁻ binds to native RpNiR. A recent crystallographic study of an RpNiR mutant suggests that NO₂⁻ may bind via nitrogen rather than through the bidentate oxygen mode typically observed in two-domain CuNiRs. In this work we have used combined quantum mechanical/molecular mechanical (QM/MM) methods to model the binding mode of NO₂⁻ with native RpNiR in order to determine whether the N-bound or O-bound orientation is preferred. Our results indicate that binding via nitrogen or oxygen is possible for the oxidised Cu(II) state of the T2Cu centre, but in the reduced Cu(I) state the N-binding mode is energetically preferred. Full article