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1.
Zhonghua Yi Xue Za Zhi ; 103(40): 3211-3218, 2023 Oct 31.
Artículo en Chino | MEDLINE | ID: mdl-37879876

RESUMEN

The abdominal wall can be treated as a whole physiological and functional entity which is composed of multiple anatomical structures and planes. Surgical approaches and technical details that required are diverse in different area. Indeed, the abdominal wall is confined by several anatomical boundaries which make these surgical planes separated. If one could dissect these boundaries, then separated spaces could be connected, establishing an ample retromuscular/preperitoneal space to accommodate the mesh of ventral hernia repair. The concept of totally visceral sac separation (TVS) is achieved. The TVS concept is a summary of diverse ventral hernia repair techniques. Since its initiation and spread, this technique has been widely accepted and implemented by domestic surgeons due to its outstanding performance. This treatise will review the relevant anatomy as well assurgical tricks by the authors that aid in performing TVS. Some of the details are more tricky and harder to understand, thus this in-depth description of the technique.


Asunto(s)
Pared Abdominal , Hernia Ventral , Laparoscopía , Humanos , Mallas Quirúrgicas , Hernia Ventral/cirugía , Endoscopía , Pared Abdominal/cirugía , Herniorrafia/métodos , Laparoscopía/métodos
2.
J Chem Phys ; 152(24): 244704, 2020 Jun 28.
Artículo en Inglés | MEDLINE | ID: mdl-32610998

RESUMEN

The development of two-dimensional (2D) magnetic materials with half-metallic characteristics is of great interest because of their promising applications in spintronic devices with high circuit integration density and low energy consumption. Here, by using density functional theory calculations, ab initio molecular dynamics, and Monte Carlo simulation, we study the stability, electronic structure, and magnetic properties of a OsI3 monolayer, of which crystalline bulk is predicted to be a van der Waals layered ferromagnetic (FM) semiconductor. Our results reveal that the OsI3 monolayer can be easily exfoliated from the bulk phase with small cleavage energy and is energetically and thermodynamically stable at room temperature. Intrinsic half-metallicity with a wide bandgap and FM ordering with an estimated TC = 35 K are found for the OsI3 monolayer. Specifically, the FM ordering can be maintained under external biaxial strain from -2% to 5%. The in-plane magnetocrystalline anisotropy energy of the 2D OsI3 monolayer reaches up to 3.89 meV/OsI3, which is an order larger than that of most magnetic 2D materials such as the representative monolayer CrI3. The excellent magnetic features of the OsI3 monolayer therefore render it a promising 2D candidate for spintronic applications.

3.
Ecotoxicol Environ Saf ; 190: 110128, 2020 Mar 01.
Artículo en Inglés | MEDLINE | ID: mdl-31891838

RESUMEN

Over the last few decades, the threat posed to biodiversity and ecosystem function by atmospheric nitrogen (N) deposition has been increasingly recognized. The disturbed nutrient balance and species composition of plants induced by higher N deposition can impact the biodiversity of the organisms that consume the plants. In this research, we implemented several experiments to estimate the effects of increased N deposition on the growth, survival, and nutrients of the dominant epiphytic lichens in the subtropical mountains in Central China to assess the lichen food amount and nutritional quality for two endangered primates endemic to China. Our results indicated that the thallus growth and propagule survival of the lichens were significantly decreased when nitrogen addition changed from 6.25 to 50.0 kg N·ha-1·y-1; it was also shown that lichen biomass could be decreased by 11.2%-70.2% when the deposition addition exceeded 6.25 kg N·ha-1·y-1. Further, our study revealed that increased nitrogen deposition also reduced the nutritional quality of the lichens via reducing the soluble protein and soluble sugar levels and increasing the fiber content, which would substantially affect the diet selection of the plants consumers in the region, particularly the populations of the two lichen-eating endangered primate species, Rhinopithecus roxellana and R. bieti. Our experimental study suggested that the nitrogen pollution derived from anthropogenic activities could cause cascading effects for the whole forest ecosystem of Central China; thus, more studies about nitrogen deposition in this region are required.


Asunto(s)
Contaminantes Atmosféricos/análisis , Monitoreo del Ambiente , Líquenes/química , Nitrógeno/análisis , Animales , Atmósfera , Biodiversidad , Biomasa , China , Ecosistema , Contaminación Ambiental , Abastecimiento de Alimentos , Bosques , Líquenes/metabolismo , Nitrógeno/metabolismo , Primates
4.
Zhonghua Yi Xue Za Zhi ; 98(36): 2933-2936, 2018 Sep 25.
Artículo en Chino | MEDLINE | ID: mdl-30293353

RESUMEN

Objective: Investigating a novel approach to treat a midline ventral hernia--totally endoscopic sublay repair (TES). The procedure will be described in detail and the safety and efficacy evaluated. Methods: During July and December 2017, eleven consecutive cases of primary and secondary epigastric midline ventral hernias were repaired using the TES procedure. A large mesh should be placed in the retrorectus position using this minimally invasive procedure. The indications for this procedure include umbilical, epigastric and incisional hernia equal in length to the rectus diastasis. Results: All operations were successful without open conversion. The mean operation time was 120 mins(80-205 min), postoperative pain was mild and the mean VAS was 2.5 on first postoperative day. The average postoperative stay in hospital was 3.3 days (2-5 days). 2 cases experienced postoperative seroma but without adverse effect on the final outcome and no recurrences during the follow-up period of 1 to 6 months. Conclusions: TES procedure is safe, practical and minimally invasive requiring no specific device and highly reproducible. Besides there is no need for expensive anti-adhesion mesh and fixation tacker which make it more cost effective. TES is a good technique for the surgical treatment of midline ventral hernia.


Asunto(s)
Hernia Ventral , Mallas Quirúrgicas , Endoscopía , Humanos , Tempo Operativo , Complicaciones Posoperatorias
5.
Beijing Da Xue Xue Bao Yi Xue Ban ; 50(4): 651-656, 2018 Aug 18.
Artículo en Chino | MEDLINE | ID: mdl-30122766

RESUMEN

OBJECTIVE: To analyze the conventional application of using comprehensive hemostatic methods during the perioperative period, and the effect of autologous blood transfusion (ABT) device compared with non-negative pressure drainage on preventing blood loss and allogenic blood transfusion after primary total knee arthroplasty (TKA). METHODS: A total of 131 patients (131 knees) with severe knee osteoarthritis who underwent unilateral primary TKA by the same surgeon in Peking University Third Hospital from June 2014 to June 2015 were enrolled in this study. The patients were divided into ABT group (64 patients) and control group (67 patients). ABT devices were used for drainage and blood transfusion in the ABT group while the control group used the non-negative pressure drainage only. The results of the drainage fluid volume, the decrease of hemoglobin, the total blood loss, the hidden blood loss and blood transfusion after TKA were compared between the two groups. RESULTS: The drainage fluid volume in ABT group was significantly higher than that in control group [515 mL (80-1 610 mL) vs. 260 mL (40-670 mL), P<0.001]. The autologous blood transfusion in ABT group was 245 mL (60-1 070 mL). There were no significant differences between the two groups in the value of hemoglobin decrease 1 day after surgery (P=0.340) and 3 days after surgery (P=0.524). There were no significant differences in the total blood loss (P=0.101) and the hidden blood loss (P=0.062) between the two groups either. There were 9 patients in the 131 patients who received allogeneic blood transfusion, of whom 5 in the ABT group (5/64, the blood transfusion rate was 7.8%) and 4 in the control group (4/67, the blood transfusion rate was 6.0%), and no significant differences in the blood transfusion rate between the two groups (P=0.943). CONCLUSION: With the conventional application of using comprehensive hemostatic methods during perioperative period, the ABT device did not show the effective result of controlling postoperative blood loss and failed to reduce the rate of allogeneic blood transfusion in patients with unilateral primary TKA. However, the ABT device could increase the drainage fluid volume and improve the patient's hospitalization expenses. Therefore, there is no need for routine application of ABT device in unilateral primary TKA.


Asunto(s)
Artroplastia de Reemplazo de Rodilla , Pérdida de Sangre Quirúrgica , Transfusión de Sangre Autóloga , Transfusión Sanguínea , Pérdida de Sangre Quirúrgica/prevención & control , Transfusión de Sangre Autóloga/instrumentación , Hemostáticos , Humanos
7.
J Anim Sci ; 95(10): 4239-4250, 2017 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-29108073

RESUMEN

Long noncoding RNA (lncRNA) has been increasingly implicated in the regulation of muscle development. Large White pigs have a higher muscle growth rate than do Mashen pigs. In the present study, the lncRNA expression profiles in skeletal muscle of these 2 pig breeds were compared at 1, 90, and 180 d of age using RNA sequencing. We obtained 2,718 million clean reads and identified a total of 5,153 novel lncRNA. We found 1,407 differentially expressed lncRNA that showed consistent expression patterns between the 2 breeds at all the 3 sampling points. Ten lncRNA were randomly selected, and their expression was validated using Real-time Quantitative PCR. In summary, this study identifies a number of lncRNA that correlate with muscle growth. The regulation and function of these lncRNA in muscle growth and development need to be further explored.


Asunto(s)
Desarrollo de Músculos/genética , ARN Largo no Codificante/genética , Porcinos/genética , Animales , Secuencia de Bases , Perfilación de la Expresión Génica/veterinaria , Masculino , Músculo Esquelético/crecimiento & desarrollo , Distribución Aleatoria , Análisis de Secuencia de ARN/veterinaria , Porcinos/crecimiento & desarrollo
8.
Beijing Da Xue Xue Bao Yi Xue Ban ; 48(2): 351-5, 2016 Apr 18.
Artículo en Chino | MEDLINE | ID: mdl-27080295

RESUMEN

OBJECTIVE: To evaluate the efficiency of the tibial coronal alignment after total knee arthroplasty with the extramedullary cutting system guided by the tibial tubercle and anterior tibial tendon, and to discuss the potential risk factors for the postoperative malalignment. METHODS: A retrospective study of 212 primary unilateral TKA surgeries (in 188 patients) in our hospital between June to December in 2014 had been analysed. All the cases were performed by one surgical group. An extramedullary tibial cutting guide system had been used, with a landmark of one third inner-medial tibial tubercle as a proximal anatomy reference, and anterior tibial tendon as a distal marker. The mechanical axis of lower extremity in full-length X-ray was measured before surgery, and the tibial prosthetic coronal alignment was checked two weeks postoperation, evaluating the accuracy of this extramedullary cutting system guided by our method. RESULTS: Since good alignment was defined as an angle within 3 degrees of the perpendicular to the mechanical axis, the tibial component positions were acceptable in 191 knees (90.1%), five knees were in valgus postoperative, and sixteen knees were in varus. There were seventeen(8.7%) in 179 knees with a preoperative varus presented malalignment after surgery, and four in 12 preoperative valgus kneess howed malalignment also, no statistical difference was found by Chi-square test(χ(2)=2.778,P=0.096), which cannot define the relationship between the varus or valgus deformity preoperation and the malalignmentposition in tibial prosthesis after surgery. Twenty-two knees suffered a severe preoperative deformity as a varus or valgus angle larger than 20 degrees with absolute value of mechanical axis before surgery and tibial prosthetic coronal alignment were 21.95 °(20.00°,26.90°)and 1.85°(0.10°, 7.10°), showed a significant difference (Z=2.11,P=0.035) compared with the data [10.65°(0.50°,19.80°)in preoperative mechanical axis and 1.10°(0.00°,4.60°)in the tibial prosthetic coronal alignment]of 190 knees who presented a mild deformity before surgery(less than 20 degrees), the result indicated the severe preoperative deformity might be a potential mal-alignment risk factor within this cutting system in TKA surgery. CONCLUSION: The tibial coronal alignment after total knee arthroplasty could achieve good results with extramedullary cutting guide, by using one third inner-medial tibial tubercle and anterior tibial tendon as a proximal and distal anatomy marker. Postoperative varus might occur in this system, and tibial prosthetic malalignment appeared more often in the patients who suffered a severe deformity before surgery.


Asunto(s)
Artroplastia de Reemplazo de Rodilla , Desviación Ósea/diagnóstico , Articulación de la Rodilla/cirugía , Tibia/cirugía , Pueblo Asiatico , Humanos , Articulación de la Rodilla/diagnóstico por imagen , Prótesis de la Rodilla , Extremidad Inferior/diagnóstico por imagen , Periodo Posoperatorio , Estudios Retrospectivos , Factores de Riesgo , Tendones , Tibia/diagnóstico por imagen
9.
Heredity (Edinb) ; 114(2): 133-42, 2015 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-25370210

RESUMEN

Relatedness between individuals is central to ecological genetics. Multiple methods are available to quantify relatedness from molecular data, including method-of-moment and maximum-likelihood estimators. We describe a maximum-likelihood estimator for autopolyploids, and quantify its statistical performance under a range of biologically relevant conditions. The statistical performances of five additional polyploid estimators of relatedness were also quantified under identical conditions. When comparing truncated estimators, the maximum-likelihood estimator exhibited lower root mean square error under some conditions and was more biased for non-relatives, especially when the number of alleles per loci was low. However, even under these conditions, this bias was reduced to be statistically insignificant with more robust genetic sampling. We also considered ambiguity in polyploid heterozygote genotyping and developed a weighting methodology for candidate genotypes. The statistical performances of three polyploid estimators under both ideal and actual conditions (including inbreeding and double reduction) were compared. The software package POLYRELATEDNESS is available to perform this estimation and supports a maximum ploidy of eight.


Asunto(s)
Funciones de Verosimilitud , Modelos Genéticos , Poliploidía , Genotipo , Heterocigoto , Endogamia , Patrón de Herencia , Modelos Estadísticos , Programas Informáticos
10.
Br J Radiol ; 85(1010): 147-52, 2012 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-22308219

RESUMEN

OBJECTIVES: Form discordance of cavity walls (FDCW) and form concordance of cavity walls (FCCW) in multislice spiral CT (MSCT) were investigated to determine their value in differentiating between peripheral lung cancer cavities and single pulmonary tuberculous thick-walled cavities. An assessment of the role of multiplanar reconstruction (MPR) in detecting FDCW and FCCW was also performed. METHODS: MSCT cross-sectional images of 116 consecutive cases (including 60 cases with available MPR images) with peripheral lung cancer cavities and 118 consecutive cases (including 62 cases with available MPR images) with single pulmonary tuberculous thick-walled cavities (wall thickness >3 mm) were retrospectively analysed. According to the characteristics of cavitary internal and external walls on MSCT, these cavities were divided into two types (FDCW and FCCW). FDCW was further divided into three subtypes (FDCW-I, FDCW-II and FDCW-III); FCCW was further divided into two subtypes (FCCW-I and FCCW-II). RESULTS: On the cross-sectional and MPR images, the total detection rate of FDCW-I and FDCW-III in peripheral lung cancer cavities was 76.7% (89/116) and 93.3% (56/60), respectively, whereas the total detection rate of FCCW-I and FCCW-II in single pulmonary tuberculous thick-walled cavities was 75.4% (89/118) and 91.9% (57/62), respectively. CONCLUSIONS: FDCW-I, FDCW-III, FCCW-I and FCCW-II were valuable in differentiating between peripheral lung cancer cavities and single pulmonary tuberculous thick-walled cavities. MPR could improve the detection of FDCW-I and FDCW-III in peripheral lung cancer cavities and FCCW-I and FCCW-II in single pulmonary tuberculous thick-walled cavities.


Asunto(s)
Carcinoma/diagnóstico por imagen , Procesamiento de Imagen Asistido por Computador/métodos , Neoplasias Pulmonares/diagnóstico por imagen , Tuberculosis Pulmonar/diagnóstico por imagen , Adulto , Anciano , Femenino , Humanos , Masculino , Persona de Mediana Edad , Tomografía Computarizada Multidetector , Estudios Retrospectivos , Tomografía Computarizada Espiral , Adulto Joven
11.
Cytotherapy ; 10(1): 90-7, 2008.
Artículo en Inglés | MEDLINE | ID: mdl-18202978

RESUMEN

BACKGROUND: C3H10T1/2 cells, from a mouse embryonic fibroblast cell line, were used to investigate the improvement of alginate-based microencapsulated cells for cellular therapy. METHODS: Purified sodium alginate (PSA) and non-purified sodium alginate (SA) were used to prepare alginate-based microcapsules, and their biocompatibility and membrane strength were then compared for the purposes of analyzing the advantages of purifying SA. In addition, poly-l-lysine (PLL) was replaced by chitosan for alginate-chitosan microcapsule preparation. The process of optimization and chemical modification of alginate-chitosan microcapsules using polyethylene glycol was also reviewed. RESULTS: The results showed improved biocompatibility and membrane strength of PSA-based microcapsules. Under optimal conditions, mesenchymal stromal cell (MSC)-loaded alginate-chitosan microcapsules with good morphology could be obtained using PSA and chitosans of medium molecular weight (1.0-2.5 x 10(5)). A chitosan solution of 0.1% (w/v) and a reaction time of 7 min between alginate and chitosan were determined as optimal preparation parameters. DISCUSSION: It could be concluded that the chemical modification of alginate-based microcapsules can improve their biocompatibility.


Asunto(s)
Alginatos/química , Materiales Biocompatibles/química , Cápsulas/química , Trasplante de Células Madre/métodos , Animales , Materiales Biocompatibles/farmacología , Técnicas de Cultivo de Célula , Línea Celular , Proliferación Celular/efectos de los fármacos , Supervivencia Celular/efectos de los fármacos , Quitosano/química , Células Madre Embrionarias/química , Células Madre Embrionarias/citología , Fibroblastos/citología , Ácido Glucurónico/química , Ácidos Hexurónicos/química , Membranas Artificiales , Ratones , Polietilenglicoles/química
12.
Phytomedicine ; 15(5): 386-8, 2008 May.
Artículo en Inglés | MEDLINE | ID: mdl-17977703

RESUMEN

The EtOAc extract of Rabdosia coetsa showed angiotensin-converting enzyme (ACE) inhibitory activity. Bioassay-guided isolation of this extract yielded ethyl caffeate (1), rosmarinic acid (2) and methyl rosmarinate (3), which inhibited ACE activity by 32.42%, 55.19% and 39.50% respectively, at the concentration of 10 microg/ml.


Asunto(s)
Inhibidores de la Enzima Convertidora de Angiotensina/química , Inhibidores de la Enzima Convertidora de Angiotensina/farmacología , Isodon/química , Extractos Vegetales/farmacología , Animales , Ácidos Cafeicos/química , Ácidos Cafeicos/farmacología , Cinamatos/química , Cinamatos/farmacología , Depsidos/química , Depsidos/farmacología , Pulmón/enzimología , Peptidil-Dipeptidasa A/efectos de los fármacos , Peptidil-Dipeptidasa A/aislamiento & purificación , Peptidil-Dipeptidasa A/metabolismo , Extractos Vegetales/química , Conejos , Ácido Rosmarínico
13.
Biochem Biophys Res Commun ; 362(4): 923-7, 2007 Nov 03.
Artículo en Inglés | MEDLINE | ID: mdl-17767917

RESUMEN

We investigated the encapsulation of BMP-2 gene-modified mesenchymal stem cells (MSCs) in alginate-poly-L-lysine (APA) microcapsules for the persistent delivery of bone morphogenic protein-2 (BMP-2) to induce bone formation. An electrostatic droplet generator was employed to produce APA microcapsules containing encapsulated beta-gal or BMP-2 gene-transfected bone marrow-derived MSCs. We found that X-gal staining was still positive 28 days after encapsulation. Encapsulated BMP-2 gene-transfected cells were capable of constitutive delivery of BMP-2 proteins for at least 30 days. The encapsulated BMP-2 gene-transfected MSCs or the encapsulated non-gene transfer MSCs (control group) were cocultured with the undifferentiated MSCs. The gene products from the encapsulated BMP-2 cells could induce the undifferentiated MSCs to become osteoblasts that had higher alkaline phosphatase (ALP) activity than those in the control group (p<0.05). The APA microcapsules could inhibit the permeation of fluorescein isothiocyanate-conjuncted immunoglobulin G. Mixed lymphocyte reaction also indicates that the APA microcapsules could prevent the encapsulated BMP-2 gene-transfected MSCs from initiating the cellular immune response. These results demonstrated that the nonautologous BMP-2 gene-transfected stem cells are of potential utility for enhancement of bone repair and bone regeneration in vivo.


Asunto(s)
Alginatos/química , Proteínas Morfogenéticas Óseas/genética , Proteínas Morfogenéticas Óseas/inmunología , Técnicas de Cultivo de Célula/métodos , Inmunidad Innata/inmunología , Células Madre Mesenquimatosas/inmunología , Polilisina/análogos & derivados , Transfección/métodos , Factor de Crecimiento Transformador beta/inmunología , Proteína Morfogenética Ósea 2 , Cápsulas , Células Cultivadas , Polilisina/química , Factor de Crecimiento Transformador beta/genética
14.
J Asian Nat Prod Res ; 9(2): 183-6, 2007 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-17454316

RESUMEN

A novel alkaloid, gaultherialine A (1), along with twenty-seven known compounds were isolated from the whole plants of Gaultheria nummularioides D. Don. The structure of the new alkaloid was elucidated as 7,8-dimethoxy-1-(4-methoxyphenyl)-4,5-dihydro-2H-benzo[e]indole-2-one N-oxide (1) on the basis of spectral evidence.


Asunto(s)
Alcaloides/aislamiento & purificación , Gaultheria/química , Alcaloides/química , Estructura Molecular
15.
J Asian Nat Prod Res ; 9(1): 1-5, 2007.
Artículo en Inglés | MEDLINE | ID: mdl-17365181

RESUMEN

A new meroditerpenoid, igeumone (1), together with 18 known compounds (2-19), were isolated from ethanolic extract of the bark of Mayodendron igeum. Their structures were determined by analysis of spectral data or comparison with authentic samples. X-ray crystallographic analysis was employed to unambiguously determine the structure of 1.


Asunto(s)
Bignoniaceae/química , Diterpenos/aislamiento & purificación , Árboles/química , China , Cristalografía por Rayos X , Diterpenos/química , Resonancia Magnética Nuclear Biomolecular , Corteza de la Planta/química , Espectrometría de Masa por Ionización de Electrospray , Espectrofotometría Infrarroja , Espectroscopía Infrarroja por Transformada de Fourier
16.
Chemosphere ; 68(1): 10-6, 2007 May.
Artículo en Inglés | MEDLINE | ID: mdl-17292453

RESUMEN

Water, suspended solid (SS) and sediment samples were collected from nine water courses in Tianjin, China and analyzed for dichlorodiphenyltrichloroethane (DDT) and its metabolites (DDXs, including o,p'-,p,p'-DDT, DDD and DDE). The average DDX concentrations in water, SS and sediment were 59+/-30 ng l(-1), 2690+/-1940 ng g(-1)dry wt. and 340+/-930 ng g(-1)dry wt., respectively. Due to the termination of the extensive agricultural application and industrial manufacture, DDXs in river sediment decreased by one order of magnitude since 1970's and low DDT fractions in these sediments were observed. Still, DDXs in the sediments near the outlets of the major manufacturers remained relatively high attributed to the historic input. DDXs in sediment were also positively correlated with organic matter content. Spatial distributions of DDXs in SS and water was different from that in sediment. For SS, a negative correlation between DDX concentration and SS content indicated a dilution effect in many rivers. Dissolved organic carbon content was the major factor affecting DDX concentrations in water phase. Wastewater discharged from dicofol manufacturers and likely illegal agricultural application were the primary reasons causing high DDT (DDE+DDD) ratios in SS and water.


Asunto(s)
DDT/análisis , Contaminación Química del Agua/análisis , China , DDT/metabolismo , Diclorodifenil Dicloroetileno/análisis , Diclorodifenildicloroetano/análisis , Sedimentos Geológicos/química , Ríos , Microextracción en Fase Sólida , Factores de Tiempo
17.
Amino Acids ; 33(3): 537-41, 2007 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-17048123

RESUMEN

Optically pure (S)-3-p-hydroxyphenyllactic acid derivatives are important intermediates of peroxisome proliferator-activated receptor alpha/gamma dual agonists and heteropeptides. Many efforts have been made for synthesis of those intermediates, but there exist some flaws yet. We observed that dielectric constants of organic solvents drastically affected diazotization of O-benzyl-L-tyrosine. Optically pure (S)-3-p-benzyloxyphenyllactic acid was obtained by simple recrystallization when DMF or DMSO of higher dielectric constant was used as a co-solvent in diazotization of O-benzyl-L-tyrosine. It was easily turned into various optically pure (S)-3-p-hydroxyphenyllactic acid derivatives.


Asunto(s)
Fenilpropionatos , Conformación Molecular , Fenilpropionatos/síntesis química , Fenilpropionatos/química , Solventes
18.
Environ Pollut ; 139(1): 183-93, 2006 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-16087280

RESUMEN

A level IV fugacity model was used to simulate the dynamic changes of gamma-hexachlorocyclohexane (gamma-HCH) concentrations in environmental media in Tianjin, China. A similar model (level III) was previously used and validated under steady state conditions; this paper explores its dynamic behavior. Application of the level IV fugacity model has been validated using independently observed gamma-HCH concentrations in various media during the early 1980s and during 2001. Sensitivity analysis was conducted using coefficient-of-variation normalized sensitivity coefficients. The model was also subject to uncertainty analysis using Monte Carlo simulation. It was found that concentrations of gamma-HCH reached within 95% of their steady-state levels in all media after less than 15 years. Around one order-of-magnitude decreases in gamma-HCH concentrations in various media occurred between 1993 and 2001. We project that gamma-HCH concentrations will decrease another 1.7-1.9 orders of magnitude to reach 1.1 (0.9-1.2) x 10(-14), 2.7 (2.5-3.0) x 10(-10), 1.2 (1.1-1.3) x 10(-7), and 6.1 (5.4-6.8) x 10(-8) mol/m(3), in air, water, soil, and sediment, respectively, by 2020. The sensitivities and true uncertainty of the model are discussed.


Asunto(s)
Contaminantes Ambientales/análisis , Hexaclorociclohexano/análisis , Insecticidas/análisis , Contaminantes Atmosféricos/análisis , China , Monitoreo del Ambiente/métodos , Sedimentos Geológicos , Residuos Peligrosos/análisis , Modelos Químicos , Método de Montecarlo , Reproducibilidad de los Resultados , Contaminantes del Suelo/análisis , Incertidumbre , Contaminantes Químicos del Agua/análisis
19.
Environ Pollut ; 142(3): 567-75, 2006 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-16360248

RESUMEN

A previously published data set of HCH isomer concentrations in topsoil samples from Tianjin, China, was subjected to geospatial analysis. Semivariograms were calculated and modeled using geostatistical techniques. Parameters of semivariogram models were analyzed and compared for four HCH isomers. Two-dimensional ordinary block kriging was applied to HCH isomers data set for mapping purposes. Dot maps and gray-scaled raster maps of HCH concentrations were presented based on kriging results. The appropriateness of the kriging procedure for mapping purposes was evaluated based on the kriging errors and kriging variances. It was found that ordinary block kriging can be applied to interpolate HCH concentrations in Tianjin topsoil with acceptable accuracy for mapping purposes.


Asunto(s)
Monitoreo del Ambiente/métodos , Hexaclorociclohexano/análisis , Residuos de Plaguicidas/análisis , Contaminantes del Suelo/análisis , China , Recolección de Datos/métodos , Interpretación Estadística de Datos , Monitoreo del Ambiente/instrumentación
20.
Chemosphere ; 60(6): 753-61, 2005 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-15939453

RESUMEN

The dynamic exposures to HCHs of individuals born between the years 1913 and 1993 in Tianjin have been simulated by connecting a fugacity model (IV) with a multimedia exposure model. Ingestion is the most important pathway for human beings to take up HCHs, and concentrations in the human body correlate with body weight changes. Accumulations of HCHs were derived assuming that the degradation in human body behaved linearly. The health risk of exposure to HCHs was measured using cancer risk and loss of life expectancy (LLE), and LLE was modified from its original definition to incorporate a dynamic calculation that takes variances in exposure into account. Monte-Carlo simulations were run to analyze the uncertainties of the model.


Asunto(s)
Contaminantes Ambientales/análisis , Contaminación de Alimentos , Hexaclorociclohexano/análisis , Insecticidas/análisis , Residuos de Plaguicidas/análisis , Factores de Edad , Peso Corporal , China , Productos Agrícolas , Monitoreo del Ambiente , Humanos , Isomerismo , Carne , Modelos Teóricos , Método de Montecarlo , Medición de Riesgo , Alimentos Marinos , Incertidumbre , Verduras
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