Investigation of the acicular aragonite growth behavior in AOD stainless steel slag during slurry-phase carbonation

This study presents a novel method for producing acicular aragonite using argon oxygen decarburization (AOD) slag while controlling the reaction temperature, reaction time, stirring speed, and the magnesium-to‑calcium stoichiometric ratio. This approach provides steel plants with an opportunity to decrease their CO2 emissions and promote efficient resource utilization and CO2 storage through the production of high-quality value-added products. The experimental results showed that reaction temperature was the most significant factor affecting the carbonation efficiency of AOD slag, followed by reaction time, stirring speed, CO2 partial pressure, and the liquid-to-solid ratio (L/S). The study also found that elevated temperature and prolonged reaction duration favored the preferential precipitation of aragonite. Additionally, raising the temperature and the magnesium-to‑calcium stoichiometric ratio was shown to enhance the formation of aragonite, affecting its crystal growth orientation and dimensions. The optimal combination of reaction parameters for the preparation of acicular aragonite was found to be the reaction time of 8 h, the magnesium-to‑calcium stoichiometric ratio of 0.8, the reaction temperature of 120 °C, and the stirring speed of 200 r·min-1. Under these conditions, the resulting acicular aragonite exhibited excellent overall uniformity, a large aspect ratio, and a smooth crystal surface, with a content of 91.49 %, a single crystal length ranging from 9.86 to 32.6 μm, and a diameter ranging from 0.63 to 2.15 μm. This study provides valuable insights into the efficient production of acicular aragonite from steel slag while reducing CO2 emissions and promoting the sustainable use of resources.

Growth mechanism, electronic properties and spectra of aluminum clusters

Density functional theory (DFT) and particle swarm optimization (PSO) have been applied to study the growth behavior, electronic properties and spectra of neutral, anionic and cationic aluminum clusters with 3-20 atoms. Many isomers have been obtained through a comprehensive structural search. The results indicate that the ground state structures of neutral and anionic aluminum clusters follow an identical periodic growth law. When the number of atoms is 6-11 and 13-18, Al atoms in these clusters grow around an octahedral cluster nucleus and an icosahedral cluster nucleus, respectively. For Al_n⁺ (n ≤ 14 and n ≠ 7) clusters, the most stable structure is different from that of Al_n or Al_n^-clusters. When n > 14, the ground state structure of Al_n⁺ clusters is similar to that of Al_n or Al_n^-clusters. The electronic properties of aluminum clusters have been analyzed by the averaged binding energy, second-order difference of energy, energy gap and dissociation energy. It is found that the Al₇⁺ and Al₁₃^- clusters have very high stability and a large energy gap and can be regarded as two superatoms. The aluminum cluster with 18 or 40 valence electrons are the least likely to lose an electron. The dissociation behavior of Al_n⁺ clusters caused by collision is reasonably explained by means of the dissociation energy. The optical absorption spectra of neutral aluminum clusters have been simulated by using the time-dependent density functional theory. The ground states of anionic aluminum clusters have been determined by comparing theoretical photoelectron spectra (PES) with experimental findings. Infrared and Raman spectra of cationic aluminum clusters have been forecasted and can assist in identifying the most stable structure in future experiments.

[Solid pseudopapillary neoplasms of the pancreas : Diagnostics, surgical treatment and postoperative outcome]

BACKGROUND

Malignant solid pseudopapillary neoplasms (SPN) are rare tumor entities of the pancreas. The prognosis for SPN is generally excellent, although some tumors have malignant potential and tend to metastasize or relapse.

OBJECTIVE

The aim was to investigate whether there are histopathological or surgical risk factors that enable the biological potential of SPN to be estimated.

PATIENTS AND METHODS

Data from patients with SPN treated in two large German pancreas centers from 2009 to 2018 were evaluated with respect to the occurrence of SPN, surgical management, histopathological tumor characteristics and the postoperative outcome.

RESULTS

A total of 22 patients with SPN (17 women, 5 men) were operated on. The median age of the patients was 37 years (range 19-69 years). At the time of surgery 20 patients showed tumor growth limited to the pancreas. A female patient with recurrence of an externally resected SPN had lymph node involvement. Another female patient had a hepatic metastatic recurrence (Union Internationale contre Cancer (UICC) stage IV) of an externally resected SPN. Although all patients survived recurrence-free during the follow-up, this patient developed liver metastases again. The survival rate up to the end of the follow-up (median 43 months; range 1-132 months) of this study was 100%.

CONCLUSION

There is a lack of knowledge of the possible parameters that can be used to predict the biological behavior of SPN. Apart from an increased likelihood of recurrence after resection of an SPN recurrence, no clear risk factors could be identified in the examined patient collective that could indicate an increased malignant potential and a possibly poorer outcome. Only a radical surgical resection with lymphadenectomy enables a reliable assessment of the tumor stage and the removal of possibly affected lymph nodes, which could be the cause of a recurrence if left intact.

Growth behavior, glucose consumption and phenol removal efficiency of Chlorella vulgaris under the synergistic effects of glucose and phenol

The use of algae is an effective approach to remove phenol and its derivatives from polluted water. The growth behavior, glucose consumption and phenol removal efficiency of Chlorella vulgaris under the synergistic effects of glucose and phenol were investigated. The evolutions of tolerance and removal efficiency of C. vulgaris to phenol under different trophic modes and glucose contents were observed. The results revealed that growth of C. vulgaris were inhibited with the increase of phenol from 0 to 400 mg L^-1 in culture media; the tolerance to phenol enhanced with the addition of glucose from 2 to 10 g L^-1, while glucose consumption was inhibited with the increase of phenol content; phenol removal efficiency varied with glucose concentrations in mixotrophic media. The finding suggested that phenol inhibited the growth of C. vulgaris and glucose assimilation under mixotrophic cultivation, while appropriate glucose addition could enhance the tolerance of C. vulgaris to phenol and affect the phenol removal efficiency.

Probing the Structural, Electronic, and Magnetic Properties of Ag n V (n = 1-12) Clusters

The structural, electronic, and magnetic properties of Ag _n V (n = 1-12) clusters have been studied using density functional theory and CALYPSO structure searching method. Geometry optimizations manifest that a vanadium atom in low-energy Ag_nV clusters favors the most highly coordinated location. The substitution of one V atom for an Ag atom in Ag _n + 1 (n ≥ 5) cluster modifies the lowest energy structure of the host cluster. The infrared spectra, Raman spectra, and photoelectron spectra of Ag _n V (n = 1-12) clusters are simulated and can be used to determine the most stable structure in the future. The relative stability, dissociation channel, and chemical activity of the ground states are analyzed through atomic averaged binding energy, dissociation energy, and energy gap. It is found that V atom can improve the stability of the host cluster, Ag₂ excepted. The most possible dissociation channels are Ag _n V = Ag + Ag _n - 1V for n = 1 and 4-12 and Ag _n V = Ag₂ + Ag _n - 2V for n = 2 and 3. The energy gap of Ag _n V cluster with odd n is much smaller than that of Ag _n + 1 cluster. Analyses of magnetic property indicate that the total magnetic moment of Ag _n V cluster mostly comes from V atom and varies from 1 to 5 μ _B. The charge transfer between V and Ag atoms should be responsible for the change of magnetic moment.

Phenolic acid allelochemicals induced morphological, ultrastructural, and cytological modification on Cassia sophera L. and Allium cepa L

The allelopathic potential of leaf aqueous extract (LAE) of Calotropis procera on growth behavior, ultrastructural changes on Cassia sophera L., and cytological changes on Allium cepa L. was investigated. LAE at different concentrations (0.5, 1, 2, and 4 %) significantly reduced the root length, shoot length, and dry biomass of C. sophera. Besides, the ultrastructural changes (through scanning electron microscopy, SEM) induced in epidermal cells of 15-day-old seedlings of Cassia leaf were also noticed. The changes induced were shrinking and contraction of epidermal cells along with the formation of major grooves, canals, and cyst-like structures. The treated samples of epidermal cells no longer seem to be smooth as compared to control. LAE at different concentrations induces chromosomal aberrations and variation in shape of the interphase and prophase nucleus in A. cepa root tip cells when compared with control groups. The mitotic index in treated onion root tips decreased with increasing concentrations of the extracts. The most frequent aberrations were despiralization at prophase with the formation of micronuclei, sticky anaphase with bridges, sticky telophase, C-metaphase, etc. The results also show the induction of ghost cells, cells with membrane damage, and cells with heterochromatic nuclei by extract treatment. Upon HPLC analysis, nine phenolic acids (caffeic acid, gentisic acid, catechol, gallic acid, syringic acid, ellagic acid, resorcinol, p-coumaric acid, and p-hydroxy benzoic acid) were identified. Thus, the phenolic acids are mainly responsible for the allelopathic behavior of C. procera.

Mesenchymal stem cell growth behavior on micro/nano hierarchical surfaces of titanium substrates

Surface topography of an orthopedic implant plays an essential role in the regulation of bone formation with surrounding bone tissue. To investigate the effects of surface topography of titanium (Ti) substrates on cellular behavior of mesenchymal stem cells (MSCs), a series of micro/nano hierarchical structures were fabricated onto micro-structured titanium (Micro-Ti) substrates via a sol-gel method with spin-coat technique. Scanning electron microscopy (SEM), surface profiler, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and water contact angle measurement were employed to certify the successful fabrication of micro/nano hierarchical structures with the presence of various nano-sized TiO2 grains (20 nm, 40 nm and 80 nm, respectively) onto micro-structured surfaces. The formation mechanism of the micro/nano hierarchical structures was proposed. Moreover, the effects of those hierarchical structures on the growth behavior of MSCs were evaluated both on cellular and molecular levels in vitro. The results confirmed that micro/nano hierarchical structures with large grains (80 nm) greatly promoted the proliferation and differentiation of MSCs comparing with other small grains (20 nm and 40 nm). The study provides an alternative for the fabrication of hierarchically structured Ti implants for potential orthopedic application.

Structural and compositional evolution of FePt nanocubes in oganometallic synthesis

In this study, the mechanisms for the formation of FePt nanocubes via pyrolysis of iron pentacarbonate [Fe(CO)5] and platinum(II) acetylacetonate [Pt(acac)2] were investigated. The time evolution of the structure, morphology, and composition of the FePt nanocubes was probed by transmission electron microscopy (TEM) at different reaction stages. On the basis of the detailed characterization, we determined the following aspects of the reaction mechanism: (1) The FePt nanocubes are rapidly formed at 160°C to 180°C by the decomposition of the precursors, and the formation of the FePt nanocubes is dominated by the nucleation of Pt-rich species followed by a slow deposition process of Fe atoms. (2) A thin Fe atomic layer is present on the FePt nanocubes, which does not influence their phase transition into a fct structure. (3) The use of Fe(CO)5 is the key factor leading to the anisotropic growth of the FePt nanocubes, and the Fe(CO)5/Pt(acac)2 molar ratio not only determines the composition of the resulting FePt nanocubes but also affects their morphology and structures.

Stability analysis of a novel epidemics model with vaccination and nonlinear infectious rate

In this paper, by considering pathogen evolution and human interventions behaviors with vaccines or drugs, we build up a novel SEIRW model with the vaccination to the newborn children. The stability of the SEIRW model with time-varying perturbation to predict the evolution tendency of the disease is analyzed. Furthermore, we introduce a time-varying delay into the susceptible and infective stages in the model and give some global exponential stability criteria for the time-varying delay system. Finally, numerical simulations are presented to verify the results.