Role of Edge Reconstruction in the Synthesis of Few-Layer Black Phosphorene

Recent advancements in preparing few-layer black phosphorene (BP) are hindered by edge reconstruction challenges. Our previous studies have revealed the factors contributing to the difficulty of growing few-layer BP. In this study, we have successfully identified three reconstructed edges in bi- and multilayer BP through a combination of the crystal structure analysis by particle swarm optimization (CALYPSO) global structure search and density functional theory (DFT). Notably, the reconstruction between adjacent layers proves more beneficial than self-passivation or maintaining pristine edges. Among the reconstructed edges, the reconstructed ZZ edge is the most stable, regardless of the number of layers. Calculated electronic band structures reveal a significant transition in the electronic properties of black phosphorus nanoribbons (BPNRs), changing from metallic to semiconducting. This insight not only enhances the understanding of the fundamental properties of BP but also provides valuable theoretical guidance for the experimental growth of BPNRs or black phosphorus nanowires (BPNWs).

The Atomic Drill Bit: Precision Controlled Atomic Fabrication of 2D Materials

The ability to deterministically fabricate nanoscale architectures with atomic precision is the central goal of nanotechnology, whereby highly localized changes in the atomic structure can be exploited to control device properties at their fundamental physical limit. Here, an automated, feedback-controlled atomic fabrication method is reported and the formation of 1D-2D heterostructures in MoS₂ is demonstrated through selective transformations along specific crystallographic orientations. The atomic-scale probe of an aberration-corrected scanning transmission electron microscope (STEM) is used, and the shape and symmetry of the scan pathway relative to the sample orientation are controlled. The focused and shaped electron beam is used to reliably create Mo₆ S₆ nanowire (MoS-NW) terminated metallic-semiconductor 1D-2D edge structures within a pristine MoS₂ monolayer with atomic precision. From these results, it is found that a triangular beam path aligned along the zig-zag sulfur terminated (ZZS) direction forms stable MoS-NW edge structures with the highest degree of fidelity without resulting in disordering of the surrounding MoS₂ monolayer. Density functional theory (DFT) calculations and ab initio molecular dynamic simulations (AIMD) are used to calculate the energetic barriers for the most stable atomic edge structures and atomic transformation pathways. These discoveries provide an automated method to improve understanding of atomic-scale transformations while opening a pathway toward more precise atomic-scale engineering of materials.

Association of COVID-19 patient’s condition with fasting blood glucose and body mass index: A retrospective study

BACKGROUND: The COVID-19 pandemic broke out in 2019 and rapidly spread across the globe. Most of the severe and dead cases are middle-aged and elderly patients with chronic systemic diseases. OBJECTIVE: This study aimed to assess the association between fasting blood glucose (FPG) and body mass index (BMI) levels in patients with coronavirus disease 2019 (COVID-19) under different conditions. METHODS: Experimental-related information (age, gender, BMI, and FPG on the second day of admission) from 86 COVID-19 cases (47 males and 39 females) with an average age of (39 ± 17) years was collected in April and November 2020. These cases were divided into three groups according to the most severe classification of each case determined by the clinical early warning indicators of severe-critically illness, the degree of progression, and the treatment plan shown in the diagnosis and treatment plan of COVID-19 pneumonia. Statistical models were used to analyze the differences in the levels of FPG and BMI, age, and gender among the three groups. RESULTS: 1. Experimental group: 21 patients with asymptomatic or and mild symptoms (group A), 45 patients with common non-progression (group B), and 20 patients with common progression and severe symptoms (group C). 2. The age differences among the three groups were statistically significant and elderly patients had a higher risk of severe disease (t= 4.1404, 3.3933, 9.2123, P= 0.0001, 0.0012, 0.0000). There was a higher proportion of females than males in the normal progression and severe disease cases (χ2= 5.512, P= 0.019). 3. The level of FPG was significantly higher in group C than in group A (t= 3.1655, P= 0.0030) and B (t= 2.0212, P= 0.0475). The number of diabetes or IFG in group C was significantly higher than in group A (χ2= 5.979, P= 0.014) and group B (χ2= 6.088, P= 0.014). 4. BMI was significantly higher in group C than in groups A (t= 3.8839, P= 0.0004) and B (t= 3.8188, P= 0.0003). The number of overweight or obese patients in group C was significantly higher than in groups A (χ2= 8.838, P= 0.003) and B (χ2= 10.794, P= 0.001). 5. Patients’ age, gender, and FPG were independent risk factors for COVID-19 disease progression (β= 0.380, 0.191, 0.186; P= 0.000, 0.034, 0.045). CONCLUSION: The levels of FPG and BMI were significantly increased in the population with common progressive and severe COVID-19. FPG and age are independent risk factors for the progression of COVID-19.

Self-passivated edges of ZnO nanoribbons: a global search

The edge structure of two-dimensional (2D) materials plays a critical role in controlling their growth kinetics and morphological evolution, electronic structures and functionalities. However, until now, the accurate edge reconstruction of ZnO nanoribbons remains absent. Here, we present results of a global search of ZnO edge structures having used the CALYPSO program combined with the density functional theory (DFT) method. In addition to a database of all the possible edge reconstructed structures of ZnO nanoribbons, the most stable edge reconstructed structures of armchair (ZnO_AC), O-enriched zigzag (O_ZZ) and Zn-enriched zigzag edges (Zn_ZZ) have been confirmed based on molecular dynamics (MD) simulation and bonding configuration analysis of atoms near the edges. The edge formation energies show that their stabilities depend on the chemical potential (μ_O) and the concentrations (ρ_O) of oxygen atoms. Interestingly, a highly stable Zn_ZZ edge exhibits a novel nanotube-like structure and metallic characteristics, while the most stable reconstructed O_ZZ edge, resembling the letter "T", exhibits a narrow direct band-gap. It is almost certain that their electronic properties are determined by the edge states.

Effect of Ligand Structures on Ligand-Protected Gold Clusters: [Au-(p-/m-/o-MBT)]1-8 Clusters

The controllable preparation of ligand-protected clusters is still an unresolved problem, which may be due to that their formation mechanism is unclear. We propose that the ligand is the key to solve the above problems. Here, by using p-, m-, and o-methylbenzenethiol ligand protected gold clusters as examples, we try to explore the effect of ligand structures on ligand-protected gold clusters. The geometrical structures, relative stabilities and surface properties of small-sized ligand-protected gold clusters [Au-SR]_1-8 (SR = p-/m-/o-MBT) have been systematically studied based on the density functional theory. The results show that the ground state structures of [Au-SR]_1-8 clusters tend to form closed rings except for [Au-SR]_1,2. The different structures of ligand have significant effect on the structures and stabilities of ligand-protected clusters. By analyzing their surface properties and possible growth patterns, it is found that [Au-SR]_1,2 clusters serve as the basic building blocks, and the larger clusters can be regarded as the combinations of them. This study provides some insights into the effect of ligands on ligand-protected clusters, which is useful for understanding the formation mechanism of ligand-protected clusters.

Structures and Electronic and Hydrogen Storage Properties of Magnesium Scandium Hydrides

MgH₂ is well known as a potential hydrogen storage material. However, its high thermodynamic stability, high dissociation temperature, slow absorption, and desorption kinetics severely limit its application. Aiming at these shortcomings, we try to improve the hydrogen storage property of MgH₂ by doping with transition metal Sc atoms. The structures and electronic and hydrogen storage properties of Mg-Sc-H systems have been systematically studied by combining the crystal structure analysis by particle swarm optimization and density functional theory method. The results show that the structure of MgScH₈ with the R3 space group is the most stable one, which is proved to be a wide-band gap (2.96 eV) semiconductor. The possible decomposition pathways, which are crucial for the applicability of R3-MgScH₈ as a hydrogen storage material, are studied, and the pathway of MgScH₈ → ScH₆ + Mg + H₂ is found to be the most favorable one under 107.8 GPa pressure, while above 107.8 GPa, MgScH₈ → Mg + Sc + 4H₂ becomes the most thermodynamically stable pathway and releases the maximum amount of hydrogen. Based on the root mean square deviation calculation, it is found that R3-MgScH₈ begins to melt at 400 K. The result of ab initio molecular dynamics simulations shows that the hydrogen release capacity (4.04 wt %) can be easily achieved at 500 K, thus making MgScH₈ a potential hydrogen storage material.

Mechanism of 2D Materials' Seamless Coalescence on a Liquid Substrate

The seamless coalescence of parallelly aligned 2D materials is the primary route toward the synthesis of wafer-scale single crystals (WSSCs) of 2D materials. The epitaxial growth of various 2D materials on a single-crystal substrate, which is an essential condition of the seamless coalescence approach, has been extensively explored in previous studies. Here, by using hexagonal boron nitride (hBN) growth on a liquid gold surface as an example, we demonstrate that growth of WSSCs of 2D materials via the seamless coalescence of self-aligned 2D islands on a liquid substrate is possible. Here we show that, in the presence of hydrogen, all the hBN edges tend to be hydrogen terminated and the coalescence of hBN islands occurs only if their crystallographic lattices of neighboring hBN islands are aligned parallelly. The mechanism of hBN self-alignment revealed in this study implies that, under the optimum experimental condition, the seamless coalescence of 2D materials on a liquid substrate is possible and thus provides guidance for synthesizing WSSCs of various 2D materials by using liquid phase substrates.

[Effects of hypoxia combined with LPS on the expression of pro- inflammatory cytokines and BNIP3 in primary cultured astrocyte]

Objective: To investigate the expression of Bcl-2/E1B-19K-interacting protein 3 (BNIP3) and inflammation in astrocytes under lipopolysaccharide ( LPS ) combined with hypoxia. Methods: Primary cultured astrocytes and neurons in vitro were divided into four groups: normoxia group; hypoxia group; LPS group; LPS plus hypoxia group (each group is provided with 3 duplicate holes). After treated with LPS(100 ng/ml), hypoxia group and LPS plus hypoxia group were placed in hypoxia cell incubator with 0.3% O₂, and normoxia group and LPS group were placed in normal cell incubator for 24 h. Primary astrocytes were divided four groups as above for 6 h,12 h and 24 h. The expression of BNIP3 in astrocytes was detected by Western blot. The expressions of tumor necrosis factor-α(TNF-ɑ), interleukin-1β (IL-1β) and interleukin-6 (IL-6) mRNA in astrocytes were detected by RT-PCR. The levels of TNF-ɑ, IL-1β and IL-6 in cultured medium were detected by ELISA. Results: Compared with the normoxia group, the expressions of inflammatory cytokines TNF-ɑ, IL-1β and IL-6 mRNA had no change in hypoxia group and were increased in LPS group and LPS plus hypoxia group (P＜0.01). Compared with the LPS group, the expressions of inflammatory cytokines IL-1β and IL-6 mRNA were increased in LPS plus hypoxia group (P＜0.05, P＜0.01). Compared with the normoxia group, the levels of inflammatory cytokines had no change in hypoxia group and the levels of TNF-ɑ and IL-6 were increased in LPS group and LPS plus hypoxia group (P＜0.01), the level of IL-1β had no change in LPS group and LPS plus hypoxia group. Compared with the LPS group, the levels of TNF-ɑ and IL-6 had no more change in LPS plus hypoxia group. BNIP3 was expressed in primary neurons and astrocytes in vitro. Compared with astrocytes in the normoxia group, the expression of BNIP3 in LPS group had no change and was increased markedly in hypoxia group and LPS plus hypoxia group (P＜0.01). Compared with neurons in the normoxia group, the expression of BNIP3 in LPS group had no change and was increased in hypoxia group and LPS plus hypoxia group (P＜0.05, P＜0.01). Compared with neurons in the hypoxia group, the expression of BNIP3 in astrocytes of hypoxia group was increased (P＜0.01). Compared with the normoxia group at the same time point, the expression of BNIP3 in LPS group had no change and was increased in hypoxia group and LPS plus hypoxia group (P＜0.05, P＜0.01). Compared with the hypoxia group at the same time point, the expression of BNIP3 was increased markedly in LPS plus hypoxia group at 6 h and 12 h (P＜0.01). Conclusion: The combination of hypoxia with LPS augmented inflammation in astrocyte and LPS enhanced the expression of BNIP3 in astrocyte under hypoxia, suggesting BNIP3 might be involved in regulating astrocyte inflammation.

Crystal Structures, Phase Stabilities, Electronic Properties, and Hardness of Yttrium Borides: New Insight from First-Principles Calculations

Yttrium borides have attracted much attention for their superconducting and high chemical stability. However, the fundamental knowledge of the mechanical properties and hardness of yttrium borides is rather lack. Here, we performed a systematic investigation on yttrium borides with various stoichiometries based on an unbiased CALYPSO structure search method and first-principles calculations. A new YB₆ compound with R3m hexagonal structure is observed, which is more stable than the experimental synthesized Pm3̅m phase. The calculated formation enthalpy, elastic constants, and phonon dispersions distinctly show that the R3m-YB₆ is energetically, mechanically, and dynamically stable. The density of states and electronic band structure reveal that all the stable yttrium borides are metallic. Based on a semiempirical method, the Vicker hardness of R3m-YB₆ is expectant to be 37.0 GPa, indicating it is a potential ultrahard metal. Our results provide insights for future synthesis and design of new type functional materials.

Structures, Mobilities, and Electronic Properties of Functionalized Silicene: Superhalogen BO2 Adsorption

The narrow band gap of silicene severely hinders its application in nanoelectronic devices. Therefore, it is significant to open the band gap of silicene and maintain its high carrier mobility. And for that, the adsorption of different coverage superhalogens BO₂ on the silicene surface have been investigated based on density functional theory and the CALYPSO method. The results show that BO₂ unit prefers to adsorb on silicene with adjacent mode irrespective of the size of substrate. The electronic structure analysis indicates that the density of states near the Fermi level are mainly contributed by Si-p and BO₂-p orbitals. (BO₂)_n-silicene exhibits metallic character with the exception of (BO₂)₂ adsorbed on 4 × 4 supercell. As for (BO₂)₂-silicene, silicene transforms from a gapless direct semiconductor to an indirect semiconductor. Furthermore, the effective electron mass of two BO₂ superhalogens on 4 × 4 silicene is estimated and found to be smaller than that of graphene. It is expected to result in higher electron mobility.

Prediction of the Iron-Based Polynuclear Magnetic Superhalogens with Pseudohalogen CN as Ligands

To explore stable polynuclear magnetic superhalogens, we perform an unbiased structure search for polynuclear iron-based systems based on pseudohalogen ligand CN using the CALYPSO method in conjunction with density functional theory. The superhalogen properties, magnetic properties, and thermodynamic stabilities of neutral and anionic Fe₂(CN)₅ and Fe₃(CN)₇ clusters are investigated. The results show that both of the clusters have superhalogen properties due to their electron affinities (EAs) and that vertical detachment energies (VDEs) are significantly larger than those of the chlorine element and their ligand CN. The distribution of the extra electron analysis indicates that the extra electron is aggregated mainly into pseudohalogen ligand CN units in Fe₂(CN)₅^¯ and Fe₃(CN)₇^¯ cluster. These features contribute significantly to their high EA and VDE. Besides superhalogen properties, these two anionic clusters carry a large magnetic moment just like the Fe₂F₅^¯ cluster. Additionally, the thermodynamic stabilities are also discussed by calculating the energy required to fragment the cluster into various smaller stable clusters. It is found that Fe(CN)₂ is the most favorable fragmentation product for anionic Fe₂(CN)₅^¯ and Fe₃(CN)₇^¯ clusters, and both of the anions are less stable against ejection of Fe atoms than Fe(CN)_n-x.

Investigation on the neutral and anionic BxAlyH2 (x + y = 7, 8, 9) clusters using density functional theory combined with photoelectron spectroscopy

The photoelectron experimental spectra measured at 266 nm and simulated spectra of B₂Al₅H₂⁻ and B₂Al₆H₂⁻ clusters.

Microhydration effects on the structures and electrophilic properties of cytidine

Adiabatic electron affinities (AEAs) for cytidine hydrates with up to four water molecules.

Structures and bonding of auropolyboroenes [Au2(B4)xB3]−, [Au2(B4)xB2]2− and [Au2(B4)xB]+ (x = 2, 3): comparison with dihydride polyboroenes

Equilibrium structures of auropolyboroenes [Au₂(B₄)_xB₃]⁻, [Au₂(B₄)_xB₂]²⁻ and [Au₂(B₄)_xB]⁺ (x = 2, 3) are obtained from density functional theory-based calculations.

Systematic theoretical investigation of geometries, stabilities and magnetic properties of iron oxide clusters (FeO)nμ(n = 1–8, μ = 0, ±1): insights and perspectives

The structural and magnetic properties of neutral and charged (FeO)_n^μ(n= 1–8,μ= 0, ±1) clusters have been studied using an unbiased CALYPSO structure searching method.

Probing the structural and electronic properties of small aluminum dideuteride clusters

Adsorption of deuterium on the neutral and anionic Aln(λ) (n=1-9, 13; λ=0, -1) clusters has been investigated systematically using density functional theory. The comparisons between the Franck-Condon factor simulated spectra and the measured photoelectron spectroscopy (PES) of Cui and co-workers help to search for the ground-state structures. The results showed that D2 molecule tends to be dissociated on aluminum clusters and forms the radial AlD bond with one aluminum atom. By studying the evolution of the binding energies, second difference energies and HOMO-LUMO gaps as a function of cluster size, we found Al2D2, Al6D2 and Al7D2(̄) clusters have the stronger relative stability and enhanced chemical stability. Also, considering the larger adsorption energies of these three clusters, we surmised that Al2, Al6 and Al7(̄) may be the better candidates for dissociative adsorption of D2 molecule among the clusters we studied. Furthermore, the natural population analysis (NPA) and difference electron density were performed and discussed to probe into the localization of the charges and reliable charge-transfer information in AlnD2 and AlnD2(̄) clusters.

Structural and relative stabilities, electronic properties, and hardness of iron tetraborides from first prinicples

First-principles calculations were carried out to investigate the structure, phase stability, electronic property, and roles of metallicity in the hardness for recently synthesized FeB4 with various different structures. Our calculation indicates that the orthorhombic phase with Pnnm symmetry is the most energetically stable one. The other four new dynamically stable phases belong to space groups monoclinic C2/m, orthorhombic Pmmn, trigonal R3̅m, and hexagonal P63/mmc. Their mechanical and thermodynamic stabilities are verified by calculating elastic constants, formation enthalpies, and phonon dispersions. We found that all phases are stabilized further under pressure. Above the pressure of about 50 GPa, the formation enthalpy of Pmmn is almost equal to that of P63/mmc phase. The analysis on density of states not only demonstrates that formation of strong covalent bonding in these compounds contributes greatly to their stabilities but also that they all exhibit metallic behavior which does not relate to the approach used. By considering metallic contributions, the estimated Vickers hardness values based on the semiempirical model show that the OsB4-structured FeB4, with a hardness of 48.1 GPa, well exceeding the limitation of superhardness (40 GPa), is more hard than the most stable phase. The others are predicted to be potential hard materials. Moreover, the atomic configuration and strong B-B covalent bonds are found to play important roles in the hardness of materials.

Phase stability, mechanical properties, hardness, and possible reactive routing of chromium triboride from first-principle investigations

The first-principles calculations are employed to provide a fundamental understanding of the structural features and relative stability, mechanical and electronic properties, and possible reactive route for chromium triboride. The predicted new phase of CrB3 belongs to the rhombohedral phase with R-3m symmetry and it transforms into a hexagonal phase with P-6m2 symmetry at 64 GPa. The mechanical and thermodynamic stabilities of CrB3 are verified by the calculated elastic constants and formation enthalpies. Also, the full phonon dispersion calculations confirm the dynamic stability of predicted CrB3. Considering the role of metallic contributions, the calculated hardness values from our semiempirical method for rhombohedral and hexagonal phases are 23.8 GPa and 22.1 GPa, respectively. In addition, the large shear moduli, Young's moduli, low Poisson's ratios, and small B∕G ratios indicate that they are potential hard materials. Relative enthalpy calculations with respect to possible constituents are also investigated to assess the prospects for phase formation and an attempt at high-pressure synthesis is suggested to obtain chromium triboride.

Structures, electrophilic properties, and hydrogen bonds of cytidine, uridine, and their radical anions: Microhydration effects

Structures, electrophilic properties, and hydrogen bonds of the neutral and anionic monohydrated nucleoside, (cytidine)H2O, and (uridine)H2O have been systematically investigated using density functional theory. Various water-binding sites were predicted by explicitly considering the optimized monohydrated structures. Meanwhile, predictions of electron affinities and vertical detachment energies were also carried out to investigate their electrophilic properties. By examining the singly occupied molecular orbital and natural population analysis, we found the excess negative charge is localized on the cytidine and uridine moiety in anionic monohydrates. This may be the reason why the strength of hydrogen bonding undergoes an obvious change upon the extra electron attachment. Based on the electron density (ρ) and reduced density gradient (RDG), we present an approach to map and analyze the weak interaction (especially hydrogen bond) in monohydrated cytidine and uridine. The scatter plots of RDG versus ρ allow us to identify the different type interactions. Meanwhile, the maps of the gradient isosurfaces show a rich visualization of hydrogen bond, van der Waals interaction, and steric effect.

[Effect of cadmium chloride on the expression and phosphorylation of mitogen-activated protein kinase in normal rat kidney epithelial cells]

OBJECTIVE

To explore the effect of cadmium chloride on the expression and phosphorylation of mitogen-activated protein kinase (MAPK) in normal rat kidney epithelial (NRK) cells.

METHODS

The NRK cells were incubated with cadmium chloride either at respective dose (0, 1, 5, 10, 20, 40 µmol/L) for 24 h or at same dose (10 µmol/L) for respective time (0, 0.5, 1.0, 2.0, 4.0, 8.0 h). Western blotting was applied to test the expression of MAPK in NRK cells (ERK1/2, p38, JNK); and phosphor-specific antibody to detect the phosphorylated MAPK (p-ERK1/2, p-p38, p-JNK).

RESULTS

There was no significant difference in the MAPK expression among the groups either treated with different doses or for different time; however, the level of phosphorylated MAPK was comparatively higher than it in control group. There was an obvious expression of p-ERK1/2 at 1.00 ± 0.06 in the group incubated with 10 µmol/L CdCl(2); and the expression in the 20 µmol/L and 40 µmol/L CdCl(2) group was 2.58 ± 0.11, 2.76 ± 0.23 respectively, which was 1.58 and 1.76 times more than it in 10 µmol/L CdCl(2) group. The differences were statistically significant (F = 827.70, P < 0.01). The respective expression of p-p38MAPK in the 20 µmol/L (2.47 ± 0.20)and 40 µmol/L CdCl(2) group (3.73 ± 0.25)was 1.47 and 2.73 times more than it in control group (1.00 ± 0.02), and the differences were also statistically significant (F = 280.06, P < 0.01). There was a dose-effect relationship of the concentration of cadmium in the expression of p-ERK1/2 (r = 0.919, t = 4.69, P = 0.009) and p-p38MAPK (r = 0.945, t = 5.79, P = 0.004). Additionally, phosphorylated MAPK expressed in a time-dependent manner. The expression of p-ERK1/2 was obvious in the group incubated for 1 h (1.26 ± 0.11), and the respective expression in the 4 h group (1.51 ± 0.07) and 8 h group (3.53 ± 0.23) was 1.5 and 3.5 times of it in the control group (1.00 ± 0.02). The differences were statistically significant (F = 427.82, P < 0.001). The expression of p-p38MAPK increased significantly in 1 h group (1.31 ± 0.07); while the respective expression in 4 h group (3.53 ± 0.32) and 8 h group (4.41 ± 0.38) was 3.5 and 4.4 times of it in control group (1.00 ± 0.03). The differences were also statistically significant (F = 280.06, P < 0.001).

CONCLUSION

Cadmium chloride could significantly enhance the phosphorylation of MAPK in NRK cells; and it is probably associated with the activation of MAPK.

3,9-Dichloro-2,4,8,10-tetra-oxa-3,9-di-phosphaspiro-[5.5]undecane-3,9-dione

In the title compound, C(5)H(8)Cl(2)O(6)P(2), the two six-membered rings display chair conformations. The P=O bond distances are 1.444 (2) and 1.446 (2) Å. Weak inter-molecular C-H⋯O hydrogen bonds are present in the crystal structure.

[Pathological analysis and mRNA expression of apoptosis genes in rat kidney tissue after subacute melamine treatment]

OBJECTIVE

to investigate pathological changes and mRNA expression of apoptosis genes bcl-2, bax and Caspase-3 in rat kidney tissue after rats are administrated with melamine for 28 days.

METHODS

10 male SD rats and 10 female SD rats in each group were administrated with three doses of melamine (low dose, middle dose, high dose) by gavage for 28 days. The animals were divided into three experimental groups and one control group. The doses for male rats were 200, 400, 800 mg/kg, but for female rats they were 150, 300, 600 mg/kg. After melamine treatment the animals were sacrificed and the kidneys were taken out for pathological analysis and for detecting mRNA expression of bcl-2, bax and Caspase-3 with fluorescent quantitative PCR assay.

RESULTS

the tubular cylinders were observed in three experimental groups. The positive rates of tubular cylinders in three groups (from low dose to high dose) were 11/20, 13/20, 16/20, respectively. Additionally, melamine induced a significant decrease in mRNA expression of bcl-2 at low dose, middle dose or high dose, bcl-2 expression decreased by 20.58% - 49.51% in three groups treated with melamine. Furthermore, bax mRNA levels increased by 44.66% - 300.96% in groups treated with three doses of melamine, and Caspase-3 mRNA levels increased by 64.76% - 360.75% in groups treated with three doses of melamine.

CONCLUSIONS

melamine could induce pathological changes of rat kidneys, and it also induces a significant alteration of apoptosis Bcl-2, Bax and Caspase-3 mRNA expression in rat kidney tissue.

The study of resonance Raman scattering spectrum on the surface of Cu nanoparticles with ultraviolet excitation and density functional theory

Cu colloid was prepared by oxidation-reduction; it was relatively steady in fixed conditions, with size about 10-30 nm. The Raman spectrum of p-hydroxybenzoic acid (PHBA) in Cu colloid solution with the ultraviolet (UV) excitation at 325 nm, was obtained, even it is usually difficult to obtain Raman signals in Ag or Au in the UV region. It was found that the Raman signal intensities result from the resonance enhanced of surface plasmon resonance of Cu nanoparticles excited at 325 nm. The adsorption behavior of PHBA on the Cu nanoparticles was studied by combining with density functional theory (DFT); it was found that the calculated Raman frequencies were in good agreement with experimental value. So one can conclude that the simplified model is probably reasonable to describe some resonance Raman experiments.

A heterogeneous model for gas transport in carbon molecular sieves

A dual resistance model with distribution of either barrier or pore diffusional activation energy is proposed in this work for gas transport in carbon molecular sieve (CMS) micropores. This is a novel approach in which the equilibrium is homogeneous, but the kinetics is heterogeneous. The model seems to provide a possible explanation for the concentration dependence of the thermodynamically corrected barrier and pore diffusion coefficients observed in previous studies from this laboratory on gas diffusion in CMS. The energy distribution is assumed to follow the gamma distribution function. It is shown that the energy distribution model can fully capture the behavior described by the empirical model established in earlier studies to account for the concentration dependence of thermodynamically corrected barrier and pore diffusion coefficients. A methodology is proposed for extracting energy distribution parameters, and it is further shown that the extracted energy distribution parameters can effectively predict integral uptake and column breakthrough profiles over a wide range of operating pressures.