Energy level measurement for organic semiconductors.

Along with the miniaturization and versatility of organic optoelectronic devices, it is desired to achieve a profound comprehension of the charge transport mechanism and even the basic device physics. The basis of these studies is the acquisition of relevant information about energy levels. This review provides a comprehensive analysis of five commonly-used techniques, including cyclic voltammetry, ultraviolet electron spectroscopy, inverse photoemission electron spectroscopy, low energy inverse photoemission spectroscopy and hot electron spectroscopy. According to the advantages and disadvantages, working mechanism, and application conditions, researchers will screen out a reliable and suitable characterization method, quickly and accurately. This should be beneficial for the efficient promotion of organic electronics and save valuable time for the related research studies.

Adequate dietary magnesium intake may protect females but not males older than 55 years from cognitive impairment.

BACKGROUND: Magnesium is an essential nutrient required to maintain brain health throughout life, and adequate magnesium intake is positively associated with cognitive performance in older adults. However, sex differences in magnesium metabolism have not been adequately assessed in humans. OBJECTIVES: We investigated sex differences in the effect of dietary magnesium intake and the risk of different types of cognitive impairment in older Chinese adults. METHODS: We collected and assessed dietary data and cognitive function status in people aged 55 years and older in northern China who participated in the Community Cohort Study of Nervous System Diseases from 2018 to 2019 to explore the relationship between dietary magnesium intake and the risk of each type of mild cognitive impairment (MCI) in sex-specific cohorts of older adults. RESULTS: The study included 612 people: 260 (42.5%) men and 352 (57.5%) women. Logistic regression results showed that for the total sample and women's sample, high dietary magnesium intake reduced the risk of amnestic MCI (ORtotal = 0.300; ORwomen = 0.190) and multidomain amnestic MCI (ORtotal = 0.225; ORwomen = 0.145). The results of restricted cubic spline analysis showed that the risk of amnestic MCI (ptotal = 0.0193; pwomen = 0.0351) and multidomain amnestic MCI (ptotal = 0.0089; pwomen = 0.0096) in the total sample and women's sample gradually decreased with increasing dietary magnesium intake. CONCLUSIONS: The results suggest that adequate magnesium intake may have a preventive effect against the risk of MCI in older women.

A networked iron and nitrogen-doped ZIF-8/MWCNTs heterostructure for oxygen reduction reaction.

Zeolitic Imidazolate Frameworks-8 (ZIF-8) is commonly used as an ideal precursor for non-noble metal catalysts because of its high specific surface area, ultra-high porosity, and N-rich content. Upon pyrolyzing ZIF-8 at 900 °C in Ar, the resulting material, referred to as Z8, displayed good activity toward the oxygen reduction reaction (ORR). Then the ZIF-8 was mixed with various conductive carbon materials, such as multiwall carbon nanotubes (MWCNTs), Acetylene black (ACET), Vulcan XC-72R (XC-72R), and Ketjenblack EC-600JD (EC-600JD), to form Z8 composites. The Z8/MWCNTs composite exhibited enhanced ORR activity owing to its network structure, meso-/microporous hierarchical porous structure, improved electrical conductivity, and graphitization. Subsequently, iron and nitrogen co-doping is achieved through the pyrolysis of a mixture comprising Fe, N precursor, and ZIF-8/MWCNTs, which is denoted as FeN-Z8/MWCNTs. The intrinsically high electrical conductivity of MWCNTs facilitated efficient electron transfer during the ORR, while the meso-/microporous hierarchical porous structure and network structure of Fe, N co-doped ZIF-8/MWCNTs promoted oxygen transport. The presence of Fe-containing species in the catalyst acted as activity centers for ORR. This strategy of preparing Z8 composites and modifying them with Fe, N co-doping offers an insightful approach to designing cost-effective electrocatalysts.

Analysis and detection using novel terahertz spectroscopy technique in dietary carbohydrate-related research: Principles and application advances.

As one of the main functional substances, carbohydrates account for a large proportion of the human diet. Conventional analysis and detection methods of dietary carbohydrates and related products are destructive, time-consuming, and labor-intensive. In order to improve the efficiency of measurement and ensure food nutrition and consumer health, rapid and nondestructive quality evaluation techniques are needed. In recent years, terahertz (THz) spectroscopy, as a novel detection technology with dual characteristics of microwave and infrared, has shown great potential in dietary carbohydrate analysis. The current review aims to provide an up-to-date overview of research advances in using the THz spectroscopy technique in analysis and detection applications related to dietary carbohydrates. In the review, the principles of the THz spectroscopy technique are introduced. Advances in THz spectroscopy for quantitative and qualitative analysis and detection in dietary carbohydrate-related research studies from 2013 to 2022 are discussed, which include analysis of carbohydrate concentrations in liquid and powdery foods, detection of foreign body and chemical residues in carbohydrate food products, authentication of natural carbohydrate produce, monitoring of the fermentation process in carbohydrate food production and examination of crystallinity in carbohydrate polymers. In addition, applications in dietary carbohydrate-related detection research using other spectroscopic techniques are also briefed for comparison, and future development trends of THz spectroscopy in this field are finally highlighted.

Going ballistic: a novel characterization for the electronic energy gap.

The energy gap of molecular semiconductors is a critical parameter in molecule-based devices because it fundamentally determines the operating principle and device performance, such as the charge transfer driving force. Hence, an accurate quantification of the energy gap of a molecular semiconductor is essential. The hot electron technique, which is implemented using a hot electron transistor and ballistic electron emission microscope, has been verified as the most powerful characterization in recent years. By monitoring the charge transport on the metal/molecule interface, an electron-injection barrier (or LUMO) and hole-injection barrier (or HOMO) can be achieved, which contributes to the electronic energy gap determination. In this review, a comprehensive comparison of these two techniques was made. It helps us to select a suitable method in specific situations and provides a profound comprehension of the charge transport process in molecular semiconductor and molecule-based devices.

Evaluation of Electroconvulsive Therapy in Adolescents With Major Depressive and Bipolar Disorders: A Retrospective Analysis.

OBJECTIVE: This study aims to provide an evaluation of electroconvulsive therapy (ECT) in hospitalized adolescents with major depressive and bipolar disorders by examining its treatment outcomes as well as comparing it with outcomes of hospitalized patients, treated as usual (TAU). METHODS: This is a retrospective study based on medical records documented between April 2011 and December 2017 from Beijing An Ding Hospital. Patients were diagnosed according to the International Classification of Diseases, Tenth Revision . The study included 288 inpatients, with 2 groups of 171 patients treated by ECT and 117 TAU. The primary outcome was measured using the severity subscale of Clinical Global Impression. Mann-Whitney U test, χ2 test, and linear regression with mixed models were used to analyze the data. RESULTS: Symptom severity reduced significantly for both groups ( ß = -0.62, t975.93 = -20.54, P < 0.001). The TAU group was associated with lower score on the severity subscale of Clinical Global Impression ( ß = 0.28, t980.32 = 8.36, P < 0.001). The ECT group had a higher remission rate (28.65%) than the TAU group (16.24%), but the time required for remission was longer ( U [ NECT = 49, NTAU = 19] = 615, z = 2.10, P = 0.04). Adverse events of ECT were barely observed. CONCLUSION: Electroconvulsive therapy is an efficacious and safe treatment for adolescents. However, as the superiority in efficacy was not evident in ECT group, its prescription should be prudently considered for younger patients who respond well to other treatments.

Deciphering different effects of ZVI and NaOH on metabolic characteristics in the process of methanogenesis recovery from VFA suppression.

Dosing zero valent iron (ZVI) or sodium hydroxide (NaOH) is the common method of addressing acidification in anaerobic digestion (AD) systems; however, few studies have discussed and compared their effects on microbial metabolism. In the present study, microbial syntrophy and metabolic pathways under ZVI and NaOH regulation are comparatively analyzed through microbial network analysis and metagenomic/metaproteomic analyses. CH4 yield in the ZVI reactor was 414 mL/gVS, an increase of 23% when compared with that in the reactor with NaOH dosing (336 mL/gVS). The methanogenesis recovery period in the ZVI reactor (37 days) was shorter than that in the NaOH reactor (48 days). Co-occurrence networks indicated that ZVI promoted Methanoculleus and Methanosarcina to establish a complex syntrophic association with SAO bacteria (Syntrophaceticus and Aminobacterium) and syntrophic acetogens (Syntrophomonas), strengthening SAO-hydrogenotrophic methanogenesis (HM) and acetoclastic methanogenesis (AM) pathways simultaneously. Metagenomic analysis showed that the relative abundance of mcrA and fwdB in the ZVI reactor was higher 27% than that in the NaOH reactor. Furthermore, through metaproteomics analysis, much more enzymes related to glucose degradation, bioconversion of butyric acid and pyruvate, conversion of formate and acetate to CO2, and production of CH4 from acetate and CO2 were significantly upregulated under ZVI regulation than under NaOH regulation (fold change relative to control [FC] > 1.5, p < 0.05). The results of the present study enhance our understanding of methanogenic mechanisms under the regulation of ZVI, providing a theoretical basis for its practical application in AD systems experiencing VFA suppression.

Association of dietary inflammatory index and metabolic syndrome in the elderly over 55 years in Northern China.

We assessed the association between the dietary inflammatory index (DII) and the development of metabolic syndrome in the elderly over 55 years in Northern China. The data of 1936 Chinese adults aged 55 years and over from a community-based neurological disease cohort study from 2018 to 2019 were analysed. Multiple logistic regression and restricted cubic splines regression were used for analysis, and social demographics, lifestyle and health-related factors were adjusted. In the fully adjusted model, the risk of metabolic syndrome increased by 1·28-fold in people with a pro-inflammatory diet. When we divide the metabolic syndrome by its components, high pro-inflammatory diet and hyperglycaemia, TAG, hypertension and abdominal obesity, we failed to observe a significant association between a high pro-inflammatory diet and HDL-cholesterol. However, these associations are moving in the expected direction. At the same time, the results of BMI subgroup analysis showed that with the increase of DII, obese people are at increased risk of metabolic syndrome, hyperglycaemia, high TAG, hypertension and abdominal obesity. Also in overweight people, the increase in DII is accompanied by an increased risk of hyperglycaemia and abdominal obesity. Higher inflammatory diet is related to metabolic syndrome, hypertension, hyperglycaemia, abdominal obesity and hypertriglyceridaemia. Further research is needed to confirm the role of inflammation and diet in the development of metabolic syndrome; however, it is desirable to reduce the dietary components associated with inflammation.

Twelve novel sesquiterpenes with anti-inflammatory and cholesterol-lowering activities from burdock leaves.

Nine new cadinane-type sesquiterpenoids (1-9) and three new eucalyptane -type sesquiterpenes (10-12) were isolated from the ethyl acetate extract of Burdock leaves, which were commonly used for preventing or treating atherosclerosis in China. Their structures were confirmed by extensive spectroscopic analysis, single-crystal X-ray diffraction analysis and ECD calculations. Compound 1 possessed the rare large conjugated skeleton. All the isolates were evaluated for anti-inflammatory and cholesterol-lowering activities by the LPS- and oxidized-low-density-lipoprotein-stimulated RAW 264.7 cells, respectively. As the results, all isolates could decrease the productions of NO, and down-regulate the accumulation of cholesterol. Among them, 4 showed the most potent cholesterol-lowering effect. For the high content of 4 in the herb, mechanistic study of 4 was performed and the results showed that 4 markedly reduced the release of pro-inflammatory mediators which was probably associated with inhibition of the PI3K/Akt and 5-LOX signaling pathways. The findings of this study demonstrated the anti-inflammatory/cholesterol-lowering effects of the new sesquiterpenes from burdock leaves, which provides chemical basis and scientific evidence for the herb used as anti-atherosclerosis agents for the further study. The sesquiterpene lactones of burdock leaves are expected to become new small molecule inhibitors for the treatment of AS.

Effect of Metformin Therapy on Biological Properties and Prognosis of Breast Cancer Patients Complicated with Type-2 Diabetes.

Objectives: To evaluate the effect of Metformin therapy on patients of breast cancer with complications of Type-2 diabetes. Methods: Altogether 102 cases of breast cancer complicated with Type-2 diabetes admitted into Hebei General Hospital from January 2019 to December 2020 were included in the study. They were divided into two groups per whether Metformin was administered in the regimen, namely Metformin group and non-Metformin group. In the meanwhile, 106 cases of breast cancer without Type-2 diabetes admitted in the same period were selected to form a control group. Three groups were compared in terms of general data (incl. age, body mass, family history, menopause or not), clinical staging, tumor histological differentiation, molecular subtyping (Incl. Luminal A, Luminal B, ERBB2+, Basal-like) and prognosis. Results: Compared with the control group, Metformin group and non-Metformin group presented more patients with an older age and post-menopause state (P<0.05), but the latter two groups were not significantly different (P > 0.05). Patients in Metformin group and non-Metformin group had higher clinical staging and histological differentiation and more cases of Basal-like subtype than those in the control group (P < 0.05), without significant difference between those two groups (P > 0.05). More cases of local relapse, lymphatic and distant metastasis were seen in Metformin and non-Metformin groups, but the differences were not significant (P > 0.05). Both groups had lower 5-year survival rates than the control group (P < 0.05). Metformin group had a higher overall survival rate as well as a survival rate free of other lethal reasons than the non-Metformin group (P < 0.05) but was not significantly different from the control group in the survival rate free of other lethal reasons (P > 0.05). Conclusions: Type-2 diabetes remains one of the risk factors affecting breast cancer development, progress and prognosis, which could lower the 5-year overall survival rate among breast cancer patients. This is especially evident among menopaused women. Metformin therapy may improve the prognosis of patients of breast cancer complicated with Type-2 diabetes.

Expressions of IGF-1R and Ki-67 in breast cancer patients with diabetes mellitus and an analysis of biological characteristics.

OBJECTIVES: There is a cross-link of insulin and insulin-like growth factor-1 (IGF-1) with each other's receptors. The present study was carried out to explore the relationship of Type-2 diabetes mellitus (T2DM) with the occurrence and development of breast cancer by analyzing the expression of IGF-1R and Ki-67, as well as the biological characteristics in breast cancer patients with and without diabetes mellitus. METHODS: A total of 102 cases of breast cancer patients with T2DM admitted in Hebei General Hospital from January 2019 to December 2020 were selected and grouped in T2DM group. While the control group included 106 cases of breast cancer patients without diabetes mellitus in the same period. Further comparison was conducted focusing on the general data, clinical stage, tumor histological grade, molecular classification and prognosis, and the expressions of IGF-1R and Ki-67 in breast cancer tissue between groups. RESULTS: Compared with control group, patients in T2DM group were elderly and accounted for a larger proportion of post-menopause (p<0.05), yet with no significant difference in body mass and family history (p>0.05). Compared with control group, T2DM group had advanced clinical stage, higher histological grade, and more common molecular type, with statistical differences between groups (p<0.05). Furthermore, there were higher proportions of local recurrence, lymph node metastasis and distant metastasis in T2DM group than those in control group, yet with no statistical significance (p>0.05). While statistical difference was found in the comparison of the 5-year survival rate, which was lower in T2DM group than that in control group (p<0.05). In addition, compared with control group, there were significant increase in both the expressions of IGF-1R and Ki-67 in T2DM group (p<0.05). CONCLUSIONS: T2DM may be one of the risk factors affecting the occurrence, development and prognosis of breast cancer, which may decrease the 5-year survival of breast cancer patients. Besides, high expressions of IGF-1R and Ki-67 may be the key factors for poor prognosis of breast cancer patients with diabetes mellitus.

[Agreement analysis and result calibration by ordinary least product regression between bioelectrical impedance analysis and dual energy X-ray absorptiometry].

OBJECTIVE: To analyze agreement of body fat percentage measured by bioelectrical impedance analysis(BIA) and dual energy X-ray absorptiometry(DXA) in Chinese adults, and to calibrate BIA measurement by ordinary least product regression(OLP). METHODS: Volunteers aged 18-65 were recruited to measure total body fat percentage and trunk fat percentage by BIA(Tanita BC-601 F) and DXA(Hologic Discovery QDR), respectively. Agreement between the two methods was compared by OLP. Bootstrap method was used to do the internal validation of the calibration equation. The calibration effect was verified by the agreement analysis of the calibrated BIA result and the DXA result. RESULTS: Before calibration, all 95%CIs of the intercepts of the OLP regression lines did not include 0, and all 95%CIs of the slopes of the OLP regression lines did not include 1. 00. After calibration, all 95% CIs of the intercepts of the OLP regression lines included 0, and all 95% CIs of the slopes included 1. 00. CONCLUSION: There are fixed bias and proportion bias between BIA and DXA in measuring total body fat percentage and trunk fat percentage in Chinese men and women. Calibration should be considered when body fat percentage is measured by BIA.

Diagnostic Capability and Influence Factors for a New Electrocardiogram Criterion in the Diagnosis of Left Ventricular Hypertrophy in a Chinese Population.

INTRODUCTION: Based on a small sample of patients with hypertension, a few studies have reported that the newly proposed SD + SV4 criterion for left ventricular hypertrophy (LVH) is better than traditional criteria. This study aimed to verify the diagnostic capability of the SD + SV4 criterion in a Chinese population with or without hypertension and to analyze the factors affecting the diagnostic accuracy of LVH. METHODS: A total of 248 patients with LVH or paroxysmal supraventricular tachycardia (PSVT) discharged from Fuwai Hospital from January 2010 to July 2018 were enrolled. Patients with LVH were diagnosed according to the left ventricular mass index calculated by the echocardiogram parameter as the gold standard in this study. The receiver operating curve (ROC) curve was performed to assess the diagnostic capability and cut-off values of the SD + SV4, RavL + SV3, and SV1 + RV5/RV6 criteria for LVH. Then, multivariate logistic regression analyses were performed to in-vestigate the factors affecting the accuracy of the SD + SV4 criterion. RESULTS: There were 170 (68.5%) patients with hypertension and 110 (44.4%) with PSVT. According to echocardiography, 107 (43.1%) patients were diagnosed with LVH. The area under the curve (AUC) of the SD + SV4 criterion was the largest compared with that of the RavL + SV3 and SV1 + RV5/RV6 criteria (AUC 0.765 vs. 0.718 vs. 0.713, respectively). The sex-specific SD + SV4 criterion had the highest consistency with the gold standard (r = 0.532 ± 0.054, p < 0.01), accompanied by the highest sensitivity (70.1%) and specificity (85.8%). The cut-off values of the sex-specific SD + SV4 criterion for LVH were ≥2.65 mV (male)/2.15 mV (female). The left ventricular ejection fraction (LVEF; OR 0.920, 95% CI 0.882-0.959, p < 0.001) was significantly different between the SD + SV4 criterion and the gold standard for LVH after adjusting for hypertension, PSVT history, body surface area, interventricular septum thickness, posterior wall thickness, and left ventricular internal diameter. CONCLUSION: The newly proposed SD + SV4 criterion provides improved sensitivity and accuracy for the diagnosis of LVH in the Chinese population. A decrease in LVEF is an independent factor affecting the diagnostic accuracy of LVH.

[Relationship between rs2282679 gene locus polymorphism and vitamin D deficiency in college students].

OBJECTIVE: To investigate the relationship between vitamin D binding protein gene rs2282679 A/C polymorphism with blood vitamin D levels. METHODS: A total of 286 eligible subjects were selected from one university in Hebei Province. Serum 25-hydroxylated vitamin D levels were measured by liquid chromatography-mass spectrometry, and gene chip was used for genotyping of rs2282679 locus. Statistical analysis was performed using R software. RESULTS: A total of 285 participants in the study completed the experiment, and result indicated that the distribution of the rs2282679 locus A/C polymorphism in the participants was consistent with the Hardy-Weinberg equilibrium. The genotype of rs2282679 was significantly associated with serum vitamin D insufficiency and deficiency(P=0. 031). Allele A was a risk factor for vitamin D insufficiency and deficiency. The OR value of allele C relative to A was 0. 65, and the genetic pattern of allele C relative to A was dominant(P=0. 03). CONCLUSION: The vitamin D-binding protein gene rs2282679 was significantly associated with serum vitamin D insufficiency and deficiency in college students, and A-allele is a risk factor accounting for vitamin D insufficiency and deficiency in college students.

Study of the Effect of Neutral Polysaccharides from Rehmannia glutinosa on Lifespan of Caenorhabditis elegans.

The problem of an aging society is becoming increasingly acute. Diseases related to aging also come with it. There are some diseases that people can't treat fundamentally. Therefore, people try to find a natural ingredient from natural medicine to treat these diseases and improve the quality of life of the elderly. With the screening of a large number of traditional Chinese medicines, we found that polysaccharides from Rehmannia glutinous (PRG) can prolong the lifespan of Caenorhabditis elegans (C. elegans). Neutral polysaccharide is the main component of PRG. In the present study, we used a C. elegans model to illustrate the stress resistance and lifespan extension effect and mechanism of two kinds of neutral polysaccharide fractions from Rehmannia glutinosa (NPRG), respectively called NPRRP and NPRR. Our data showed that two kinds of neutral polysaccharides fractions could extend the lifespan and delay senescence of wild-type worms. Moreover, the mechanism study revealed that NPRG was able to promote the nuclear localization of DAF-16 resulting in the activation of antioxidant enzymatic systems under oxidative stress. We also observed that NPRG didn't increase the lifespan of mutants with daf-16 portion loss of function, suggesting NPRG prolonging the lifespan partially required the daf-16 gene on the insulin/IGF-1 signaling pathway (IIS). NPRG was found to have no effect on Escherichia coli OP50 (E.coli OP50) growth and pharyngeal pump movement of nematodes, indicating that the anti­aging effect of NPRG is not realized by the caloric restriction. However, mRNA levels of daf-2 were remarkably decreased after NPRG treatment. Thus daf-2 lost its inhibitory effect on the expression of daf-16 and had a continuous stimulation effect on the IIS, then prolonged the life of nematodes. Overall, our results illustrated the potential utilization of NPRG as a functional pharmaceutical ingredient to increase stress resistance and extend the life of C. elegans via the IIS, which could be developed as a natural supplement agent.

Biochemical and Structural Studies of the Interaction between ARAP1 and CIN85.

Arf-GAP with Rho-GAP domain, ANK repeat and PH domain-containing protein 1 (ARAP1), Cbl-interacting protein of 85 kDa (CIN85), and casitas B-lineage lymphoma (Cbl) play important roles in epidermal growth factor receptor (EGFR) internalization and recycling. In previous studies, ARAP1 was found to interact with CIN85, and their interaction attenuated the ubiquitination of EGFR. However, the molecular mechanism was still unclear. In this study, we first biochemically and structurally characterized the interaction between ARAP1 and CIN85, and found that the CIN85 SH3B domain bound to the ARAP1 PXPXXRX (except P) XXR/H/K motif with high affinity and specificity. Based on this binding model, we further predicted other potential CIN85 binding partners and tested their interactions biochemically. Moreover, our swapping data and structure alignment analysis suggested that the ß2-ß3 loops of the CIN85 SH3 domains and the H87ARAP1/E132CIN85 interaction were critical for ARAP1 binding specificity. Finally, our competitive analytical gel-filtration chromatography and isothermal titration calorimetry (ITC) results showed that ARAP1 could compete with Cbl for CIN85 binding, which provides a biochemical basis for the regulatory roles of ARAP1 in the CIN85-mediated EGFR internalizing process.

Brachytherapy in the treatment of breast cancer.

Brachytherapy is an important radio-therapeutic modality for a variety of malignancies, including prostate cancer, cervix cancer, breast cancer, vagina cancer, endometrium cancer, head and neck cancer, and many more. This technique has been shown to be an effective and safe non-pharmaceutical treatment with fewer serious complications and better outcome than other treatments for breast cancer. Every year, hundreds of thousands of patients around the world benefit from brachytherapy, which reliably delivers a relatively higher radiation dose to the intended target. However, the follow-up time, patient eligibility criteria, treatment strategy, and radiation doses used in published studies are somewhat inconsistent, making it difficult to strictly compare and evaluate the performance of the treatment. More rigorous studies are required to confirm the safety of this technique and to make outcome data more comparable. In this review, we focus on recent advances in breast brachytherapy techniques and provide an overview of outcomes, cosmetic outcome, toxicity, complications, and limitations of brachytherapy for the treatment of breast cancer. We also summarize the clinical outcomes and toxicity results in patients receiving or not receiving brachytherapy.

Systematic biochemical characterization of the SAM domains in Eph receptor family from Mus Musculus.

The Eph receptor family is the largest subfamily of receptor tyrosine kinases and well-known for their pivotal roles in axon guidance, synaptogenesis, artery/venous differentiation and tumorigenesis, etc. Activation of the Eph receptor needs multimerization of the receptors. The intracellular C-terminal SAM domain of Eph receptor was reported to mediate self-association of Eph receptors via the homo SAM-SAM interaction. In this study, we systematically expressed and purified the SAM domain proteins of all fourteen Eph receptors of Mus musculus in Escherichia coli. The FPLC (fast protein liquid chromatography) results showed the recombinant SAM domains were highly homogeneous. Using CD (circular dichroism) spectrometry, we found that the secondary structure of all the SAM domains was typically alpha helical folded and remarkably similar. The thermo-stability tests showed that they were quite stable in solution. SEC-MALS (size exclusion chromatography coupled with multiple angle light scattering) results illustrated 200 µM Eph SAM domains behaved as good monomers in the size-exclusion chromatography. More importantly, DLS (dynamic light scattering) results revealed the overwhelming majority of SAM domains was not multimerized in solution either at 200 µM or 2000 µM protein concentration, which indicating the SAM domain alone was not sufficient to mediate the polymerization of Eph receptor. In summary, our studies provided the systematic biochemical characterizations of the Eph receptor SAM domains and implied their roles in Eph receptor mediated signaling pathways.

[Determination of Trace Germanium in Plant Samples by Dry Ashing-Atomic Fluorescence Spectrometry].

To reduce the limit of detection (LOD) and allow the accurate determination of Ge, a dry ashing method was performed to enrich the Ge in plant samples. A method for the determination.of trace Ge in plant samples by HG-AFS was established. Study of the effect of temperature on the ashing of plant samples showed that no volatile loss of Ge occurred even at 900 °C. Additional experiments indicated that a 4 h burning process at 600 °C would be sufficient to fully ash the plant samples. Various digestion methods (involving nitric acid, hydrofluoric acid, and sulfuric acid digestion methods) for ashed samples were investigated. High-temperature ashing with large sample weights was used, which could reduce the reagent doses and the method's LOD effectively and simultaneously, the precision of the method was improved. The method's LOD was 0.27 ng · g(-1), and the relative standard deviation was 3.99%-6.81%. Verified with national biological reference materials (grade I), the proposed method was accurate and reliable.

Vector scattering from one-dimensional periodic perfectly conducting surface: transverse magnetic polarization.

Based on the Rayleigh hypothesis and Floquet's theorem, a vector method for studying electromagnetic wave scattering from a one-dimensional periodic conducting surface with tapered transverse magnetic (TM) wave incidence is presented. The fields are represented by vectors instead of scalars so that the vector behavior of scattering (such as cross polarization) can be naturally explored. The new formulation opens a wide range of applications of the method, concerning not only gratings used in TM polarization but also conical diffraction, crossed gratings, two-dimensional problems, photonic band gaps, nonlinear optics, etc. The numerical results are consistent with the T-matrix method in the particular case in which the plane of incidence is perpendicular to the generators of the surface. For the general case in which the plane of incidence is not perpendicular to generators of the surface, the proposed method obtains significant results that reveal cross-polarized and anisotropic characteristics in the scattering while the energy balance is kept satisfactory. This straightforward approach is much more efficient than the T-matrix; thus it is suitable to extend to other more involved periodic scattering problems.