[Clinical effects of retrograde anterolateral thigh flaps in repairing anterior knee joint wounds under the concept of precise flap surgery].

Objective: To introduce the methods of retrograde anterolateral thigh flaps in repairing anterior knee joint wounds under the concept of precise flap surgery and to explore the clinical effects. Methods: A retrospective observational study was conducted. From August 2014 to March 2022, 7 patients with anterior knee joint wounds were treated with retrograde anterolateral thigh flap under the guidance of the concept of precise flap surgery in the 920th Hospital of Joint Logistic Support Force of PLA. Among them, 6 were males and 1 was female, aged 36 to 66 years. The sizes of wounds were 7 cm×5 cm to 15 cm×11 cm after debridement. All the patients were performed with computed tomography angiography (CTA), the donor and recipient sites were evaluated according to the precise flap surgery method, and the optimal pedicle, perforator, and pivot of flaps were chosen. The flap sizes were 10 cm×6 cm to 20 cm×9 cm, and all the donor sites of flaps were sutured directly. The consistency of the intraoperative exploration with preoperative CTA was observed. The flap survival and occurrence of complications were observed after surgery. The color, appearance, texture, and occurrence of complications were followed up. At the last follow-up, the blood supply of flaps was evaluated using the blood circulation evaluation indicators of Chinese Medical Association Hand Surgery Branch's trial criteria for digital replantation function evaluation, and the function of knee joint was evaluated using knee joint scoring system of hospital for special surgery. Results: The flap condition of the intraoperative exploration was completely consistent with that of preoperative CTA. The flaps survived completely after surgery in 6 patients, while necrosis at the edge of the flap occurred in 1 patient, which healed after dressing change. All the flaps were hyperperfused after surgery, and the color of the flaps gradually became normal after 1 week. Follow-up of 7 to 44 months showed that the color, appearance, and texture were well in all the patients, while local osteomyelitis at the proximal tibia occurred in 1 patient. At the last follow-up, all the 7 patients had excellent blood circulation; the function score of knee joint was 69 to 91, which was evaluated as excellent in 3 cases, good in 3 cases, and fair in 1 case. Conclusions: The retrograde anterolateral thigh flap has large variations, and the application of precise flap surgery method can accurately understand the variations before surgery, guide the design and cutting of the flaps, thus achieving precise repair of anterior knee joint wounds, with good repair outcome.

[HIV self-testing reagent use in pre-exposure prophylaxis and related factors in men who have sex with men].

Objective: To understand the current status of HIV self-testing reagent use in pre-exposure prophylaxis (PrEP) and related factors in men who have sex with men (MSM). Methods: From December 2018 to December 2019, "Gold data" online platform (www.jinshuju.com) was used to conduct multicenter PrEP studies in Shenyang, Beijing, Chongqing and Shenzhen of China. Results: A total of 1 222 MSM PrEP users were included in the multicenter study. The average age of the participants was (31.5±8.7) years, and the number of sexual partners in the past three months was 3 (P25,P75:2,6). The proportions of those who did not use condoms in anal sex with fixed, casual and commercial partners were 62.7% (456/727), 56.3% (440/781) and 41.0% (16/39), respectively. Up to 74.5% (910/1 222) of participants had used HIV self-testing reagents, and the number of HIV self-testing during last year was 3 (P25,P75:2,5). The multivariate logistic regression analysis indicated that compared with age group >40 years, those with education level of junior high school or below, those with psychological identity as female, event driven PrEP users, those never using new type drugs in past 3 months, the participants aged 18- years (aOR=2.06, 95%CI: 1.35-3.14), 26- years (aOR=2.72, 95%CI: 1.77-4.17), 31- years (aOR=1.76, 95%CI: 1.19-2.59), undergraduates (aOR=2.18, 95%CI: 1.35-3.49), graduate students and above (aOR=3.06, 95%CI: 1.69-5.54), those with psychological identity as male (aOR=3.22, 95%CI: 1.55-6.70), daily PrEP users (aOR=1.35, 95%CI: 1.03-1.78), and new type drug users in the past three months (aOR=1.72, 95%CI: 1.30-2.28) had higher proportions of HIV self-testing behaviors. Conclusions: The proportion of HIV self-testing in MSM PrEP users was high, while it was relatively low in older age group, event driven PrEP users and MSM never using new type drugs. To assess and improve the effectiveness and compliance of PrEPs, it is necessary to provide better HIV self-testing service for MSM with low HIV self-testing rate.

Histological subtypes of solid-dominant invasive lung adenocarcinoma: differentiation using dual-energy spectral CT.

AIM: To investigate the value of dual-energy spectral computed tomography (DESCT) for evaluating the histological subtypes of solid-dominant invasive lung adenocarcinoma (SILADC). MATERIALS AND METHODS: Sixty-seven patients with SILADC were enrolled. All patients underwent DESCT and were divided into Group I (those with a lepidic/acinar/papillary predominant pattern) and Group II (those with a solid/micropapillary predominant pattern) based on their correlation with prognosis. Patient clinicopathological characteristics, DESCT morphological features, and quantitative parameters of the tumours were compared between both groups. Multiparametric analysis was performed using binary logistic regression with DESCT findings. Receiver operating characteristic (ROC) curves were used to assess the diagnostic performance of single-parameter and multiparametric analysis. RESULTS: Patient gender, lymph nodes status, pathological TNM stage, and histological differentiation significantly differed between the two groups (all p<0.05). Moreover, significant differences were observed between both groups in DESCT morphological features including tumour size, necrosis, calcification, air bronchogram, and vascular convergence sign, and quantitative parameters including K40-65 keV, effective atomic number, and water concentration on unenhanced CT and iodine concentration in the arterial and venous phases (all p<0.05). Multiparametric analysis showed that tumour size, air bronchogram, K40-65 keV and effective atomic number on unenhanced CT were the most effective variations for predicting the histological subtypes of SILADC and obtained an area under the ROC curve (AUC) of 0.906. CONCLUSIONS: DESCT was useful for differentiating histological subtypes with different prognosis of SILADC.

High expression of SHMT2 is correlated with tumor progression and predicts poor prognosis in gastrointestinal tumors.

OBJECTIVE: Gastrointestinal tumors are malignant tumors with high morbidity. Mitochondrial serine hydroxymethyltransferase 2 (SHMT2) is a key enzyme in the synthesis of serine and glycine, which has prognostic and therapeutic value for many malignant tumors. However, the role of SHMT2 in gastric cancer (GC), esophageal cancer (ESCC), and colorectal cancer (CC) has not been clarified. PATIENTS AND METHODS: The expression of SHMT2 was detected in GC, ESCC, and CC by immunohistochemistry and reverse real time transcription-polymerase chain reaction. The relationships between SHMT2 expression and clinicopathologic characteristics, recurrence-free survival (RFS), and disease-specific survival (DSS) were analyzed by the survival analysis and correlation analysis. RESULTS: The positive expression rate of SHMT2 in GC, ESCC, and CC was 74.1%, 69.2%, and 71.7%, respectively. Patients with high expression of SHMT2 had a worse prognosis. In GC, high SHMT2 expression had positive correlation with lymph node metastasis (p=0.005) and histological grade (p=0.002). In ESCC, high SHMT2 expression had positive correlation with pT classification (p=0.033) and pM classification (p=0.029). In CC, high SHMT2 expression had positive correlation with tumor size (p=0.004), lymph node metastasis (p=0.035), TNM stage (p=0.007), and histological grade (p=0.020). Notably, SHMT2 expression was an independent prognostic factor for RFS and DSS in GC, ESCC, and CC (p<0.05). CONCLUSIONS: SHMT2 is upregulated in GC, ESCC, and CC. The high expression of SHMT2 is correlated with gastrointestinal tumors progression, and poor prognosis, which is a potential new target for the diagnosis and treatment of gastrointestinal tumors.

Tunable hybridization of graphene plasmons and dielectric modes for highly confined light transmit at terahertz wavelength.

We theoretically report a novel graphene-based hybrid plasmonic waveguide (GHPW) by integrating a GaAs micro-tube on a silica spacer that is supported by a graphene-coated substrate. In comprehensive numerical simulations on guiding properties of the GHPW, it was found that the size of hybrid plasmonic mode (TM) can be reduced significantly to ~10-4(λ2/4), in conjunction with long propagation distances up to tens of micrometers by tuning the the waveguide's key structure parameters and graphene's chemical potential. Moreover, crosstalk between two adjacent GHPWs that are placed on the same substrate has been analyzed and ultralow crosstalk can be realized. The proposed scheme potentially enables realization of the various high performance nanophotonic components-based subwavelength plasmonic waveguides in terahertz domain.

Hypergravity-assisted chemical liquid deposition of nano-granular film on the inner surface of a quartz tube.

Transparent tubes with functions of heating and temperature measurement are badly required in the visualization investigation of two-phase flows and flow-boiling heat transfer. In order to prepare such a tube, we introduced a cost-effective and energy-efficient procedure of hypergravity-assisted chemical liquid deposition (HACLD) to produce transparent and conductive silver (Ag) films on the inner surfaces of quartz tubes, typically 50 mm in length and 8 mm in inner diameter with a set-up that was designed and built for this purpose. Precursors of organometallic Ag precursor solutions were prepared by dissolving silver citrate and 1,2-diaminopropane in 2-methoxyethanol with required concentration for the chemical liquid deposition process. Semitransparent and conductive Ag films formed inside the required quartz tubes under specific heating process in hypergravity. One of the films was about 47 nm in thickness, 23 Ω per square sheet resistance, and 30% optical transmittance. This attempt may pave a way for the understanding of the film forming mechanism in hypergravity, and the development of a film preparation technology of HACLD.

Predictors of high on-aspirin platelet reactivity in elderly patients with coronary artery disease.

OBJECTIVES: Previous studies have illustrated the link between high on-aspirin platelet reactivity (HAPR) with increasing thrombotic risks. The aim of our study was to investigate relative risk factors of HAPR in elderly patients with coronary artery disease. METHODS: Elderly, hospitalized coronary artery disease patients on regular aspirin treatment were enrolled from January 2014 to September 2016. Medical records of each patient were collected, including demographic information, cardiovascular risk factors, concomitant drugs and routine biological parameters. Arachidonic acid (AA, 0.5 mg/mL) and adenosine diphosphate (ADP, 5 µmol/L) induced platelet aggregation were measured via light transmission assay (LTA) to evaluate antiplatelet responses, referred as LTA-AA and LTA-ADP. RESULTS: A total of 275 elderly patients were included, with mean age of 77.2±8.1 years, and males accounted for 81.8%. HAPR was defined as LTA-AA in the upper quartile of the enrolled population. HAPR patients tended to have lower renal function (P=0.052). Higher serum uric acid (SUA) level, as well as lower platelet count, hemoglobin and hematocrit were observed in HAPR patients, with a higher proportion of diuretics use (P<0.05). Multivariate analysis revealed that SUA (OR: 1.004, 95% CI: 1.000-1.007, P=0.048), platelet count (OR: 0.994, 95% CI: 0.989-1.000, P=0.045), hematocrit (OR: 0.921, 95% CI: 0.864-0.981, P=0.011) and concomitant P2Y12 receptor inhibitors use (OR: 1.965, 95% CI: 1.075-3.592, P=0.028) were correlated with HAPR. Spearman's correlation analysis demonstrated an inverse association of LTA-AA with hematocrit (r=-0.234, P<0.001), hemoglobin (r=-0.209, P<0.001) and estimated glomerular filtration rate (r=-0.132, P=0.031). CONCLUSION: SUA, platelet count, hematocrit and P2Y12 receptor inhibitors use were independently correlated with HAPR. These parameters might provide novel therapeutic targets for optimizing antiplatelet therapy.

[A Fisher discriminant model to predict the outcome of postoperative blood pressure in primary aldosteronism].

Objective: To establish a Fisher discriminant model in order to predict the outcome of postoperative blood pressure for primary aldosteronism (PA). Methods: A total of 83 cases from the First Affiliated Hospital of Chongqing Medical University were enrolled and divided into two groups: cure group and not cure group according to postoperative blood pressure. Fisher stepwise discriminant analysis was used to establish a discriminant model, and compared with aldosteronoma resolution score (ARS) and nomogram model by receiver operating characteristic curve. Results: Hypertension was cured in 52 cases, and 31 cases remained uncured. Patients in uncured group were older, and had bigger body mass index (BMI), longer duration of hypertension, higher serum triglyceride (TG), more types of antihypertensive drug, higher incidence of diabetes, smoking and alcohol intake, less typical nodules on computed tomography imaging, lower estimated glomerular filtration rate (eGFR) and high density lipoprotein cholesterol. The discriminant model based on BMI, types of antihypertensive drugs, typical nodules on CT, eGFR and TG was established and the cut-off value was 0.195 9, with a sensitivity of 86.5% and a specificity of 83.9%. The area under the curve was 0.857 (95% CI: 0.764-0.951), which was higher than that of ARS (0.733, 95% CI: 0.619-0.847) and the nomogram model (0.735, 95% CI: 0.619-0.851). Conclusion: The Fisher discriminant model had a high value to predict the outcome of postoperative blood pressure in PA.

Preclinical study on induction of pluripotent stem cells from urine of dilated cardiomyopathy patients.

OBJECTIVE: Dilated cardiomyopathy (DCM) is featured by left or bilateral ventricular dilation combined with systolic dysfunction. Its clinical manifestations include heart enlargement, cardiac failure, arrhythmia and cardiac arrest. Medication and heart transplantation have but only limited treatment effect on DCM. MATERIALS AND METHODS: Induced pluripotent stem cell (iPSC) treatment provides a new solution for DCM treatment. Human renal epithelial cells were extracted from the urine of patients with DCM and transfected with Sendai virus carrying OCT3/4, Sox2, Klf4 and c-Myc gene to generate iPSCs by reprogramming. RESULTS: The morphology and pluripotency of iPSCs obtained from the renal epithelial cells from patients with DCM were confirmed, as well as the growth characteristics, immunohistochemical features and surface markers of embryonic stem cells. Teratoma was formed in vivo. CONCLUSIONS: We demonstrated that it was feasible to obtain iPSCs from the urine of patients with DCM. This technique lays down the cytological foundation for understanding the pathogenesis and for drug screening and gene therapy for DCM.

PREVALENCE OF NONTOXIC NODULAR GOITER AFTER A NEARLY TWO-DECADE UNIVERSAL SALT IODIZATION IN A LITTORAL REGION OF SHANDONG PROVINCE, CHINA.

INTRODUCTION: With the introduction of iodized salt, more and more people are exposed to iodine sufficiency in some regions. The purpose of this study was to investigate the prevalence of nontoxic nodular goiter (NTNG) in the littoral region with high iodine supply after a nearly two- decade universal salt iodization. SUBJECTS AND METHODS: Eight hundred and thirty- five participants (from 25~65 years; males 421 and females 414) were invited for the study from Huan-cui District of Weihai City, Shandong Province from January 2013 to September 2014. All participants were inspected and diagnosed by endocrinologists according to the thyroid function tests and the thyroid gland imaging. After the normal diet of three days, the urine samples of the participants were collected between 8:00AM and 9:00AM and the urinary iodine (UI) concentrations were analyzed using Urinary Iodide Test Kit. RESULTS: The overall prevalence of NTNG in the region was 40.1%, and different prevalence occurred in the different age ranges (p<0.01). The prevalence of NTNG was 32.51%, 37.44%, 49.70%, 58.57 and 74.77% in the age group of ≤ 30, 31-40, 41-50, 51-60 and >60 years, respectively. Meanwhile, the prevalence of NTNG in women (42.08%) was higher than that in men (34.29%, p<0.05). The median of UI concentrations were 139.4µg/L and 101.5µg/L for the group with NTNG and without NTNG, respectively (p<0.01). However, there was no significant difference in UI concentrations among the groups with different age ranges (p>0.05), and statistical difference was not observed for UI concentrations between women and men (p>0.05). Intriguingly, higher UI concentrations were found in the group with larger thyroid size (p<0.01). CONCLUSION: The iodine excess can lead to the high occurrence of nodular goiter in the littoral region, and individual UI concentration detection is recommended for the iodine nutritional status analysis among normal people when Universal Salt Iodization (USI) continues to be implemented in the region.

AT1R A1166C polymorphism and risk of pregnancy-induced hypertension: a meta-analysis of case control studies.

PURPOSE: The purpose of this study was to perform a quantitative review of previous case control studies examining the association between AT1R A1166C polymorphism and pregnancy-induced hypertension (PIH). MATERIALS AND METHODS: Odds ratio (OR) and 95% confidence intervals (CI) were used as measures of effect sizes. Overall effect sizes were derived using a random-effects model or fixed-effects model when appreciated, and stratified by ethnicity. Funnel plots and Egger's regression asymmetry tests were utilized for publication bias detection. RESULTS: A total of ten articles (including 920 PIH cases and 1408 controls) were included in this meta-analysis. The overall effect sizes (OR = 2.14, 95% CI: 1.54-2.98, p < 0.00001) of additive model indicated PIH patients had a significant higher frequency of allele C. Meanwhile, the OR of the dominant model was 2.22 (95% CI: 1.51-3.26,p < 0.00001) which signified that PIH patients also had a significant higher frequency of AC+CC genotypes. The subgroup analyses were in line with the overall outcomes except the Caucasians PIH patients had a non-significant CA+CC genotypes (OR = 1.37, 95% CI: 0.95-1.98, p > 0.05). The Egger's test of additive model (p = 0.451) and dominant model (p = 0.623) revealed no statistical significance for publication bias. CONCLUSION: The meta-analysis suggested that the AT1R Al166C polymorphism was significantly associated with the PIH, especially in Asian subjects.

Changes in histone acetylation during oocyte meiotic maturation in the diabetic mouse.

Although there is considerable evidence that diabetes can adversely affect meiosis in mammalian oocytes, acetylation status of oocytes in a diabetic environment remains unclear. The objective was to determine acetylation or deacetylation patterns (based on immunostaining) of H3K9, H3K14, H4K5, H4K8, H4K12, and H4K16 sites at various stages during meiosis in murine oocytes from control and diabetic mice. According to quantitative real time polymerase chain reaction (qPCR), mean ± SEM relative expression of Gcn5 (1.70 ± 0.14 at metaphase [M]I and 1.27 ± 0.01 at MII, respectively), Ep300 (1.74 ± 0.04 at MI and 1.80 ± 0.001 at MII), and Pcaf (2.01 ± 0.03 at MI and 1.41 ± 0.18 at MII) mRNA in oocytes from diabetic mice were higher than those from controls (P < 0.05), whereas there was no difference (P > 0.05) during the germinal vesicle (GV) stage between the two groups (1.23 ± 0.04 for Gcn5, 0.82 ± 0.06 for Ep300, and 0.80 ± 0.07 for Pcaf). Conversely, relative mRNA expression concentrations of Hdac1, Hdac2, Hdac3, Sirt1 and Sirt2 during the germinal vesicle stage were lower in oocytes of diabetic mice (0.24 ± 0.03 for Hdac1, 0.11 ± 0.001 for Hdac2, 0.31 ± 0.03 for Hdac3, 0.28 ± 0.02 for Sirt1, and 0.55 ± 0.02 for Sirt2; P < 0.05). Similarly, the expression concentrations of these genes at the MI stage were lower in oocytes from diabetic mice (0.79 ± 0.12 for Hdac1, 0.72 ± 0.001 for Hdac2, 0.02 ± 0.001 for Sirt1, and 0.84 ± 0.08 for Sirt2; P < 0.05). Their expression concentrations at the MII stage were also lower in oocytes from diabetic mice (0.46 ± 0.03 for Hdac1, 0.93 ± 0.01 for Hdac2, 0.56 ± 0.01 for Hdac3, 0.01 ± 0.002 for Sirt1, and 0.84 ± 0.04 for Sirt2; P < 0.05). At the MI stage, however, there was no difference in the expression of Hdac3 between the two groups of oocytes (0.96 ± 0.03; P > 0.05). Taken together, diabetes altered the intracellular histone modification system, which may have contributed to changes in histone acetylation, and may be involved in the compromised maturation rate of oocytes in diabetic humans.

Molecular mechanics modeling of deformation and failure of super carbon nanotube networks.

A generalized molecular structure mechanics (MSM) model is proposed to investigate the deformation and failure behaviors of super carbon nanotubes (SCNTs) within the quasi-static approximation. The failure mechanism of the SCNTs with Y- and X-type junctions was examined by combining a failure criterion for the breakage of the carbon-carbon bonds in the CNT networks. The carbon-carbon bonds are modeled as elastic bars with equivalent stiffness and break as their elongation ratio reaches only 19%, which means that the broken carbon-carbon bonds are ineffective in terms of the Morse potential function. It is shown that the MSM method, combined with the failure criterion of the carbon-carbon bonds, is a powerful approach to simulate the deformation and failure of both Y junctions and X junctions with different chiralities and sizes. The deformation and failure modes of these junctions which involve rotation, bending and stretching of the CNT arms are predicted using the present model and the effects of various parameters of the junctions on their mechanical behaviors are discussed.

One-year monthly survey of rotavirus, astrovirus and norovirus in three sewage treatment plants in Beijing, China and associated health risk assessment.

To evaluate the presence and distribution of the three main viruses (rotavirus, astrovirus, and norovirus) responsible for human acute gastroenteritis in sewerage system an one-year study was carried out in Beijing, China. A total of 96 samples of influent and effluents from three sewage treatment plants (STPs) were collected from November 2006 to October 2007. Silica was used to concentrate viral particles from water samples and a reverse transcriptase-nested polymerase chain reaction (RT-nested PCR) method was used for detection of viruses. Viruses could be detected in 35.4% (34/96) of the water samples analyzed, where human rotavirus was the most frequently detected (32.3%, 31/96), followed by human astrovirus (6.3%, 6/96) and human norovirus (3.1%, 3/96). According to the quantitation results of rotaviruses, which were gained by the real-time quantitative RT-PCR method with SYBR Green I , it was known that the distributions of rotaviruses in influents and effluents of three STPs were quite similar, i.e., abundant in cold weather (from October to March) and less prevalent in warm weather (from April to September). According to the estimated exposure dose, exposure frequency, as well as the acceptable annual risk level, it was shown that the rotaviruses in the reused wastewater after conventional treatment process presented potential risk to human health through both occupational and accidental exposure.

One-year monthly survey of rotavirus, astrovirus and norovirus in three sewage treatment plants (STPs) in Beijing, China and associated health risk assessment.

To evaluate the presence and distribution of the three main viruses (rotavirus, astrovirus, and norovirus) responsible for human acute gastroenteritis in sewerage systems, a one-year study was carried out in Beijing, China. A total of 96 samples of influent and effluents from three sewage treatment plants (STPs) were collected from November 2006 to October 2007. Silica was used to concentrate viral particles from water samples and a reverse transcriptase-nested polymerase chain reaction (RT-nested PCR) method was used for detection of viruses. Virus(es) could be detected in 35.4% (34/96) of the water samples analysed, where human rotavirus was the most frequently detected one (32.3%, 31/96), followed by human astrovirus (6.3%, 6/96) and human norovirus (3.1%, 3/96). According to the quantitation results of rotaviruses, which were gained by the real-time quantitative RT-PCR method with SYBR Green I, it was known that the distributions of rotaviruses in influents and effluents of three STPs were quite similar, i.e., abundant in cold weather (from October to March) and less prevalent in warm weather (from April to September). According to the estimated exposure dose and exposure frequency, as well as the acceptable annual risk level, it was shown that the rotaviruses in the reused wastewater after conventional treatment process presented potential risk to human health through both occupational and accidental exposure.

First molecular detection of group A rotaviruses in drinking water sources in Beijing, China.

The most prevalent group A rotavirus found in the diarrheic children was also determined in drinking water sources including raw water, treated water and tap water in Beijing, and then the possible contamination contributions to tap water for human consumption were discussed in this study. A total of 26 raw water samples, 77 treated water samples and 143 tap water samples in Beijing were collected for analysis of group A rotavirus from April 2006 to August 2007. According to the results, it was shown that group A rotaviruses occurred in 9 raw water samples (34.6%), 9 treated water samples (11.7%) and 32 tap water samples (22.4%) during the sampling period, and low disinfectant residuals or a vulnerability of the distribution system to pressure transients, in addition to raw water, may account for the group A rotaviruses contamination to tap water. The rotavirus contamination observed in this study may highlight a potential public health risk and illustrate the importance of including routine virological analysis of drinking water supplies during winter time in Beijing.

Enhanced mechanical properties of single-walled carbon nanotubes due to chemical functionalization.

Recent studies have shown that the chemical functionalization of carbon nanotubes weakens most of their mechanical properties such as the critical buckling force under compression and the critical buckling moment under torsion. However, the mechanical properties including the critical bending curvature and the critical bending moment of single-walled carbon nanotubes can be improved after functionalization as shown in this paper. The molecular mechanics simulations reveal that there exists an optimum functionalization degree at which the critical curvatures of the functionalized carbon nanotubes reaches its maximum value. The critical curvatures of the carbon nanotubes increase with increasing functionalization degree below the optimum value, while the critical curvatures change little as the functionalization degree is beyond the optimum value. The influences of the bending directions and the aspect ratios of the functionalized carbon nanotubes are also examined via molecular mechanics simulations.

Resonance analysis of multi-layered graphene sheets used as nanoscale resonators.

A stacked plate model for the vibration of multi-layered graphene sheets (MLGSs), in which the van der Waals (vdW) interaction between layers is described by an explicit formula, is presented. Explicit formulae are derived for predicting the natural frequencies of double- and triple-layered graphene sheets, and they clearly indicate the effect of vdW interaction on the natural frequencies. The natural frequencies are calculated for various numbers of layered graphene sheets, and the results show that the vdW interaction has no influence on the lowest natural frequency (classical frequency) of an MLGS but plays a significant role in all higher natural frequencies (resonant frequencies) for a given combination of m and n. The vibration modes that are associated with the classical frequencies for each sheet of an MLGS are identical. In contrast, the vibration modes that are associated with the resonant frequencies are non-identical and give various vibration patterns, which indicates that MLGSs are highly suited to use as high frequency resonators.

[Determination of fatty acids in shark cartilage by GC-MS using microwave-assisted digestion and derivatization].

A rapid microwave-assisted digestion and derivatization method for the determination of fatty acids in shark cartilage by GC-MS was developed. The optimum conditions for digestion and derivatization were studied in detail using orthogonal design. The digestion and derivatization were accomplished in 4 minutes at 600 W microwave power using HCl-methanol (1:4, V/V) as digestion and derivatization solvent, and the extraction of the target analytes could be carried out simultaneously. This method is rapid, solvent-saving, and particularly suitable for the rapid determination of fatty acids in solid samples.

[Studies on retinoids. IV. Design, synthesis and structure-activity relationships of di-t-butylphenyl compounds].

Retinoic acid and its analogues play important roles in modulating cell growth, differentiation, immunity and apoptosis. Clinically they are used for cancer chemoprevention and chemotherapy. Based upon the moiety of 3,5-di-t-butyl-4-hydroxy phenyl ring, a series of substituted aromatic amide, ester and chalcones were designed and synthesized, which mimic the molecular shape, size, and spacial disposition of functional groups of retinoic acid. The general structure is as follows: [formula: see text] where R stands for hydrogen atom or methyl group, Y is the linkage -CONH-, -NHCO-, -COO-, -COCH = CH-, or a member of a heterocycle, X represents various substituents at different positions. The SAR indicates that the presence of hydrophobic group(s) at one end of the molecule, and a carboxyl group at the other end, and a conjugative system of molecule are necessary and full prerequisite for exhibiting activity. Loss of any one factor of them will abolish the activity. Being obligatory for anti-oxidative effect, the phenolic hydroxy group does not convey biological activity, because after methylation of the hydroxy group the compound increases the differentiation-inducing activity and loses the anti-oxidative effect, indicating that there is no correlation between the two activities. With a stable conformation of two phenyl rings with cis-conformation N-methylated acyl amide (No. 30) features in bent shape of the molecule, instead of an extended conformer, which is taken by the non-N-methylated partner and all-trans retinoic acid. A bent conformer of No. 30 accounts for the inactivity. In this paper compounds No. 4f, 4g, 5a, 7, 13, 32, 37, and 38 exhibited significant activity among them 4-[3-(3, 5-di-t-4-methoxyphenyl)-3-oxo-1-propenyl] benzoic acid (No. 38) showed high activity comparable to that of retinoic acid. The pharmacological action of No. 38 is under investigation.