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1.
Zhonghua Wei Chang Wai Ke Za Zhi ; 26(10): 977-985, 2023 Oct 25.
Artigo em Chinês | MEDLINE | ID: mdl-37849269

RESUMO

Objective: To evaluate the safety of double and a half layered esophagojejunal anastomosis in radical gastrectomy. Methods: This prospective, multi-center, single-arm study was initiated by the Affiliated Cancer Hospital of Zhengzhou University in June 2021 (CRAFT Study, NCT05282563). Participating institutions included Nanyang Central Hospital, Zhumadian Central Hospital, Luoyang Central Hospital, First Affiliated Hospital of Henan Polytechnic University, First Affiliated Hospital of Henan University, Luohe Central Hospital, the People's Hospital of Hebi, First People's Hospital of Shangqiu, Anyang Tumor Hospital, First People's Hospital of Pingdingshan, and Zhengzhou Central Hospital Affiliated to Zhengzhou University. Inclusion criteria were as follows: (1) gastric adenocarcinoma confirmed by preoperative gastroscopy;(2) preoperative imaging assessment indicated that R0 resection was feasible; (3) preoperative assessment showed no contraindications to surgery;(4) esophagojejunostomy planned during the procedure; (5) patients volunteered to participate in this study and gave their written informed consent; (6) ECOG score 0-1; and (7) ASA score I-III. Exclusion criteria were as follows: (1) history of upper abdominal surgery (except laparoscopic cholecystectomy);(2) history of gastric surgery (except endoscopic submucosal dissection and endoscopic mucosal resection); (3) pregnancy or lactation;(4) emergency surgery for gastric cancer-related complications (perforation, hemorrhage, obstruction); (5) other malignant tumors within 5 years or coexisting malignant tumors;(6) arterial embolism within 6 months, such as angina pectoris, myocardial infarction, and cerebrovascular accident; and (7) comorbidities or mental health abnormalities that could affect patients' participation in the study. Patients were eliminated from the study if: (1) radical gastrectomy could not be completed; (2) end-to-side esophagojejunal anastomosis was not performed during the procedure; or (3) esophagojejunal anastomosis reinforcement was not possible. Double and a half layered esophagojejunal anastomosis was performed as follows: (1) Open surgery: the full thickness of the anastomosis is continuously sutured, followed by embedding the seromuscular layer with barbed or 3-0 absorbable sutures. The anastomosis is sutured with an average of six to eight stitches. (2) Laparoscopic surgery: the anastomosis is strengthened by counterclockwise full-layer sutures. Once the anastomosis has been sutured to the right posterior aspect of the anastomosis, the jejunum stump is pulled to the right and the anastomosis turned over to continue to complete reinforcement of the posterior wall. The suture interval is approximately 5 mm. After completing the full-thickness suture, the anastomosis is embedded in the seromuscular layer. Relevant data of patients who had undergone radical gastrectomy in the above 12 centers from June 2021 were collected and analyzed. The primary outcome was safety (e.g., postoperative complications, and treatment). Other studied variables included details of surgery (e.g., surgery time, intraoperative bleeding), postoperative recovery (postoperative time to passing flatus and oral intake, length of hospital stay), and follow-up conditions (quality of life as assessed by Visick scores). Result: [1] From June 2021 to September 2022,457 patients were enrolled, including 355 men and 102 women of median age 60.8±10.1 years and BMI 23.7±3.2 kg/m2. The tumors were located in the upper stomach in 294 patients, mid stomach in 139; and lower stomach in 24. The surgical procedures comprised 48 proximal gastrectomies and 409 total gastrectomies. Neoadjuvant chemotherapy was administered to 85 patients. Other organs were resected in 85 patients. The maximum tumor diameter was 4.3±2.2 cm, number of excised lymph nodes 28.3±15.2, and number of positive lymph nodes five (range one to four. As to pathological stage,83 patients had Stage I disease, 128 Stage II, 237 Stage III, and nine Stage IV. [2] The studied surgery-related variables were as follows: The operation was successfully completed in all patients, 352 via a transabdominal approach, 25 via a transhiatus approach, and 80 via a transthoracoabdominal approach. The whole procedure was performed laparoscopically in 53 patients (11.6%), 189 (41.4%) underwent laparoscopic-assisted surgery, and 215 (47.0%) underwent open surgery. The median intraoperative blood loss was 200 (range, 10-1 350) mL, and the operating time 215.6±66.7 minutes. The anastomotic reinforcement time was 2 (7.3±3.9) minutes for laparoscopic-assisted surgery, 17.6±1.7 minutes for total laparoscopy, and 6.0±1.2 minutes for open surgery. [3] The studied postoperative variables were as follows: The median time to postoperative passage of flatus was 3.1±1.1 days and the postoperative gastrointestinal angiography time 6 (range, 4-13) days. The median time to postoperative oral intake was 7 (range, 2-14) days, and the postoperative hospitalization time 15.8±6.7 days. [4] The safety-related variables were as follows: In total, there were 184 (40.3%) postoperative complications. These comprised esophagojejunal anastomosis complications in 10 patients (2.2%), four (0.9%) being anastomotic leakage (including two cases of subclinical leakage and two of clinical leakage; all resolved with conservative treatment); and six patients (1.3%) with anastomotic stenosis (two who underwent endoscopic balloon dilation 21 and 46 days after surgery, the others improved after a change in diet). There was no anastomotic bleeding. Non-anastomotic complications occurred in 174 patients (38.1%). All patients attended for follow-up at least once, the median follow-up time being 10 (3-18) months. Visick grades were as follows: Class I, 89.1% (407/457); Class II, 7.9% (36/457); Class III, 2.6% (12/457); and Class IV 0.4% (2/457). Conclusion: Double and a half layered esophagojejunal anastomosis in radical gastrectomy is safe and feasible.


Assuntos
Adenocarcinoma , Laparoscopia , Neoplasias Gástricas , Idoso , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Adenocarcinoma/cirurgia , Anastomose Cirúrgica/métodos , Flatulência/complicações , Flatulência/cirurgia , Gastrectomia/métodos , Laparoscopia/efeitos adversos , Complicações Pós-Operatórias/etiologia , Estudos Prospectivos , Qualidade de Vida , Estudos Retrospectivos , Neoplasias Gástricas/patologia
4.
Zhonghua Yi Xue Za Zhi ; 101(34): 2703-2709, 2021 Sep 14.
Artigo em Chinês | MEDLINE | ID: mdl-34510877

RESUMO

Objective: To investigate the value of spleen density in predicting the prognosis of patients with gastric cancer after radical gastrectomy. Methods: A total of 415 patients with gastric cancer who underwent radical resection in the Department of General Surgery, Affiliated Cancer Hospital of Zhengzhou University from January 2012 to December 2015 were retrospectively analyzed. Of the patients, there were 295 males and 120 femles with a median age of 59 years (range 28-83 years). The patients were divided into diffuse decreased spleen density group (DROSD) (spleen density≤43.0 HU, n=118) and non-diffuse decreased spleen density group (N-DROSD) (spleen density>43.0 HU, n=297) according to the density of spleen detected by computed tomography (CT). The receiver operating characteristic (ROC) curve was used to identify the checkpoint of spleen density in predicting the recurrence of the gastric cancer in those patients. The relationship with clinicopathological factors and prognosis in the two groups were further analyzed. Results: The optimal critical value of spleen density for predicting postoperative recurrence of gastric cancer was 43.0 HU, the area under the curve of ROC was 0.608, and the sensitivity and specificity was 84.9% and 40.4%, respectively. Spleen density was related to albumin, hemoglobin, neutrophil lymphocyte ratio (NLR) and tumor diameter in patients with gastric cancer (all P<0.05). The 5-year disease-free survival rate and 5-year disease-specific survival rate of all the patients was 45.5% and 50.1%, respectively. Univariate survival analysis showed that age, NLR, PLR, tumor location, tumor diameter, Lauren classification, TNM stage, nerve invasion, vascular invasion, DROSD and adjuvant chemotherapy were all related to the 5-year disease-free survival rate (all P<0.05); Age, NLR, tumor location, tumor diameter, Lauren classification, TNM stage, nerve invasion, vascular invasion, DROSD and adjuvant chemotherapy were all related to the 5-year disease-specific survival rate (all P<0.05). Multivariate survival analysis showed that high NLR level (HR=1.501, 95%CI: 1.136-1.984), late TNM stage (HR=2.559, 95%CI: 1.850-3.539), DROSD (HR=2.093, 95%CI: 1.571-2.788) and no adjuvant chemotherapy (HR=1.583, 95%CI: 1.204-2.083) were independent risk factor for the 5-year disease-free survival rate (all P<0.05). Late TNM stage (HR=1.938, 95%CI: 1.395-2.692), DROSD (HR=1.566, 95%CI: 1.180-2.078) and no adjuvant chemotherapy (HR=1.336, 95%CI: 1.016-1.758) were independent risk factors for the 5-year disease-free survival rate (all P<0.05). For stage Ⅰ patients, the 5-year disease-free survival rates of DROSD group and N-DROSD group was 78.6% and 83.7%, respectively; and the 5-year disease-specific survival rates was 85.7% and 89.8%, respectively (both P>0.05). For stage Ⅱ and Ⅲ patients, the 5-year disease-free survival rates of DROSD group and N-DROSD group was 15.4% and 48.8%, respectively, and the 5-year disease-specific survival rates was 17.3% and 54.0%, respectively (all P<0.001). Conclusion: As an imaging evaluation method, spleen density is a new tool, which can be used as a prognostic indicator for gastric cancer patients.


Assuntos
Neoplasias Gástricas , Adulto , Idoso , Idoso de 80 Anos ou mais , Gastrectomia , Humanos , Masculino , Pessoa de Meia-Idade , Recidiva Local de Neoplasia , Estadiamento de Neoplasias , Prognóstico , Estudos Retrospectivos , Baço/patologia , Neoplasias Gástricas/cirurgia
6.
Zhonghua Yi Xue Za Zhi ; 100(42): 3319-3322, 2020 Nov 17.
Artigo em Chinês | MEDLINE | ID: mdl-33202494

RESUMO

Objective: To explore the application value of carbon nanoparticles labeled node staining in D2 radical resection of gastric cancer with neoadjuvant chemotherapy. Methods: The retrospective cohort study was conducted. The clinicopathological data of 82 patients with gastric cancer who were admitted to Henan Tumor Hospital from April 2016 to April 2019 were collected. 38 patients who used carbon nanoparticles labeled node staining were in the observation group, while other 44 patients were in the control group. Data analysis including the operation and results of harvested of lymph nodes. Results: All patients successfully completed the operation.Thirty-eight patients successfully completed the injection of carbon nanoparticles. Surgery: observation group operating time was (150±28) min, intraoperative blood loss was (207±121) ml, group operating time was (140±23) min, intraoperative blood loss was (256±182) ml. There was no statistically significant difference between the two groups. Detection of Lymph node: A total of 1 260 lymph nodes were detected in the observation group and 981 in the control group. In the observation group, the mean lymph node sorting time was (17.2±3.3) min, the average number of harvested lymph node was 33.2±10.4, the number of the first station of lymph node was 19.8±5.3, the second station of lymph node was 13.4±6.4, the number of harvested small node(<5 mm) was 673, the positive lymph nodes was 13(range,1-31). They were all higher than those in the control group, which were (20.6±4.4)min,22.3±6.6, 12.6±4.1, 9.7±3.2,432,6 (range,1-13) , respectively. The difference between the two groups was statistically significant (P<0.05). The metastasis rate was 19.1% (241/1 260) in observation group and 16.5%(162/981) in the control group. The difference was no statistical(P>0.05). The rate of black -dyed harvested lymph node was 54.4%(686/1 260) in carbon nanoparticles group. Conclusions: The application of carbon nanoparticles labeled node staining in D2 radical resection of gastric cancer with neoadjuvant chemotherapy is feasible and safe. It can increase the number of lymph nodes detected, which is beneficial to the evaluation of chemotherapy effect and prognosis of patients.


Assuntos
Nanopartículas , Neoplasias Gástricas , Carbono , Humanos , Excisão de Linfonodo , Linfonodos , Metástase Linfática , Terapia Neoadjuvante , Estudos Retrospectivos , Coloração e Rotulagem , Neoplasias Gástricas/tratamento farmacológico , Neoplasias Gástricas/cirurgia
8.
Zhonghua Wei Chang Wai Ke Za Zhi ; 23(10): 969-975, 2020 Oct 25.
Artigo em Chinês | MEDLINE | ID: mdl-33053992

RESUMO

Objective: For gastric cancer patients undergoing total gastrectomy, the esophagojejunal anastomosis is the main site of postoperative anastomotic leakage. How to improve the safety of the esophagojejunal anastomosis is a hot topic. This study evaluated the safety of double and a half layered esophagojejunal anastomosis in total gastrectomy for gastric cancer. Methods: A retrospective cohort study was conducted. Clinical data of 764 gastric cancer patients, who were diagnosed as gastric adenocarcinoma by preoperative gastroscopicbiopsy and were judged to be able to complete R0 resection by imaging examination, in the Affiliated Tumor Hospital of Zhengzhou University (Henan Cancer Hospital) from May 2015 to May 2019 were retrospectively collected and analyzed. two and a half layered esophagojejunal anastomosis was used in the treatment group (295 cases), and the routine anastomosis was used in the control group (469 cases). Postoperative complicating including anastomosis-assisted complications were compared between the two groups. Results: The baseline data of two groups were not significantly different (all P>0.05). All the patients successfully completed the operation. In observation group and control group, the total operative time [(140.7±27.0) minutes vs. (139.6±22.8) minutes], intraoperative blood loss [(200.6±111.0) ml vs. (214.4±114.1) ml], anastomosis time [(20.4±4.3) minutes vs. (19.9±4.6) minutes], time to first flatus [(4.1±1.1) days vs. (4.2±1.1) days], time to fluid diet [(5.4±1.0) days vs. (5.5±0.9) days], time to postoperative nasointestinal tube removal [(9.8±3.2) days vs. (10.0±2.3) days], and postoperative hospital stay [(15.4±6.5) days vs. (15.9±5.6) days] were not significantly different (all P>0.05). Compared to the control group, the treatment group had lower rates of anastomosis-associated complications [1.7% (5/295) vs. 4.7% (22/469), χ(2)=4.768, P=0.029] and anastomotic leakage [1.0% (3/295) vs.3.4% (16/469), χ(2)=4.282, P=0.039]. The differences in the incidence of anastomotic stenosis and anastomotic bleeding were not statistically significant between the two groups (both P>0.05). In the treatment group and control group, rates of total postoperative complication [34.2% (101/295) vs. 32.2% (151/469), χ(2)=0.838, P=0.360] and severe complication [Clavinen-Dindo grade III and above; 4.7% (14/295) vs. 7.2% (34/469), Z=-1.465, P=0.143] were not significantly different as well. Conclusion: Two and a half layered esophagojejunal anastomosis is safe and feasible in total gastrectomy for gastric cancer and can reduce anastomosis-associated complications.


Assuntos
Esofagoplastia , Esôfago/cirurgia , Jejuno/cirurgia , Neoplasias Gástricas , Adenocarcinoma/patologia , Anastomose Cirúrgica , Fístula Anastomótica/etiologia , Gastrectomia , Humanos , Estudos Retrospectivos , Neoplasias Gástricas/cirurgia
11.
Rev Sci Instrum ; 90(1): 013302, 2019 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-30709192

RESUMO

This paper describes the radio frequency (RF) measurement and tuning result of a 13 MeV Alvarez-type drift tube linac (DTL) for a compact pulsed hadron source (CPHS) at Tsinghua University. The design, machining, assembly, and alignment of the DTL are presented for integrity. The CPHS project consists of a high-current proton linac (13 MeV, 16 kW, peak current of 50 mA, 0.5 ms pulse width at 50 Hz), a neutron target station, a small-angle neutron scattering instrument, and a neutron imaging/radiology station. The linac contains an electron cyclotron resonance ion source, a low energy beam transport line, a four-vane radio frequency quadrupole (RFQ) accelerator, an Alvarez-type DTL, a high energy beam transport line, and a RF power supply and distributor. Construction on the CPHS started in June 2009, and the CPHS has provided 2000 h since 2013 to users with the neutrons produced by the 3 MeV proton beam from the radio frequency quadrupole bombarding on the beryllium target as an achievement of its mid-term objective. Presently, the tuning of the assembled DTL cavity has been completed successfully. The 4.3-m-long DTL consists of 40 accelerating cells, among which 39 full-length drift tubes (DTs) are suspended inside the cavity, and two half-length DTs are mounted inside the two end flanges of the cavity. Each DT contains a permanent magnet quadrupole. Thirteen post couplers and nine tuners are available for the tuning of the field. The relative error of the field after tuning is within ±1.6%, with a tilt sensitivity within ±33%/MHz in all cells. The beam energy will reach its designed value of 13 MeV after the DTL is installed in the beam line downstream the 3 MeV RFQ accelerator.

12.
Zhonghua Yi Xue Za Zhi ; 97(9): 687-690, 2017 Mar 07.
Artigo em Chinês | MEDLINE | ID: mdl-28297830

RESUMO

Objective: To investigate the feasibility, safety and efficacy of preoperative CT in the classification of adenocarcinoma of the esophagogastric junction. Methods: A total of 517 consecutive patients from May 2012 to June 2016 with esophagogastric junction carcinoma in the department of general surgery of Henan Cancer Hospital was retrospectively analyzed, according to the clinical pathological data of three type four layer method and statistics of various types of surgery in patients with preoperative enhanced CT. Results: 517 patients were successfully received surgery, including 152 cases of type Ⅰ(131 cases of complete abdominal surgery, 21 cases of abdominal incision diaphragm in thoracic surgery), 239 cases of type Ⅱ (177 cases of complete abdominal surgery, 62 cases of abdominal incision diaphragm in thoracic surgery), Ⅲ/Ⅳ type choice of chest abdominal surgery in 126 cases. The operation time was (102±17) min, the amount of hemorrhage was (136±18) ml, the dominant anastomotic fistula happened in 16 cases, 5 cases of pancreatic fistula, 7 cases of intestinal obstruction, anastomotic stenosis in 3 cases, thoracic and abdominal sensation in 12 cases, all the complications were cured by conservative treatment. The average value of esophageal resection margin was(5.1±0.6)cm, 2 cases with positive residual tumor margin and average length of stay was (8.9±1.6)d. Conclusion: Using preoperative enhanced CT in the adenocarcinoma of the esophagogastric junction to choose surgical approach can ensure the safety margin. What's more, unnecessary thoracotomy is reduced which is expected to be a new classification method for the operation of esophagogastric junction cancer.


Assuntos
Adenocarcinoma , Junção Esofagogástrica , Neoplasias Esofágicas , Hemorragia , Humanos , Metástase Linfática , Duração da Cirurgia , Estudos Retrospectivos , Neoplasias Gástricas , Toracotomia , Tomografia Computadorizada por Raios X
13.
Zhonghua Yi Xue Za Zhi ; 97(6): 443-446, 2017 Feb 14.
Artigo em Chinês | MEDLINE | ID: mdl-28219132

RESUMO

Objective: To explore the technical advantages of artery approach in lymph node sortingofrectal cancer. Methods: Sixty patients with rectal cancer who treated in general surgery department of Henan provincial tumor hospitalfrom July 2015 to January 2016 were enrolled. Patientswere divided into two groupsrandomly.Lymph node sorting methods of control group andobservation group were the traditional method and the artery approach method respectively. The total number of lymph nodes, the average inspection number, the patients number of lymph nodes less than 12, the number of positive lymph nodes, the metastasis rate of the patients, the number of average diameter less than 5 mm, the number of the positive lymph nodes which average diameter less than 5 mm, the sorting time of lymph nodes, the total number of every stationand other indicators were collected and compared. Results: There wasa significant difference between the observation group and the control groupin the total number(553 vs 395, P<0.05), the number of positive ones(96 vs 54, P<0.05), average inspection number(18.43±5.93 vs 13.27±1.96, P=0.000), the sorting time (min) (14.1±2.5 vs 17.4±3.2, P=0.000), the average diameter less than 5 mm number(4.73±1.31 vs 1.23±1.14, P=0.000), the number of positive ones average diameter less than 5 mm(0.97±1.03 vs 0.20±0.55, P=0.010), the first(8.17±4.58 vs 5.07±1.96, P=0.000) and second station(6.57±1.87 vs 4.90±1.69, P=0.001)inspection number.The inspection number less than 12, the positive rate of lymph node, the metastatic rate of the patient and the inspection number of third station have no significant differences (all P≥0.05). Conclusion: Theartery approach method inrectal cancer lymph node inspectionhas many advantages such as simple operation, obtaining more lymph nodes and more accurate pathological staging.


Assuntos
Neoplasias Retais , Artérias , Humanos , Excisão de Linfonodo , Linfonodos , Metástase Linfática , Estadiamento de Neoplasias
14.
Arch Virol ; 152(8): 1553-8, 2007.
Artigo em Inglês | MEDLINE | ID: mdl-17458619

RESUMO

We amplified gag sequences from 66 individuals infected with HIV-1 CRF07_BC during 2003-2005 in the Xinjiang region of China. A novel deletion of 7aa (including a KELY motif) in the central region of the CRF07_BC gag p6 domain was detected, which has not been reported in other HIV-1 subtypes. Further deletions of up to 13aa (including KQE and KELY motifs) was also found in this domain, representing the biggest natural deletion up to now. Moreover, the CD4+ count and viral load level indicated that 1-13aa deletions in CRF07_BC gag p6 do not have a significant effect on viral replication and fitness.


Assuntos
Produtos do Gene gag/genética , HIV-1/classificação , HIV-1/genética , Recombinação Genética , Deleção de Sequência , Sequência de Aminoácidos , Produtos do Gene gag/química , Genes gag , Infecções por HIV/virologia , Humanos , Dados de Sequência Molecular , Filogenia , Reação em Cadeia da Polimerase , Alinhamento de Sequência , Análise de Sequência de DNA , Abuso de Substâncias por Via Intravenosa/complicações , Produtos do Gene gag do Vírus da Imunodeficiência Humana
15.
Artigo em Chinês | MEDLINE | ID: mdl-17086276

RESUMO

BACKGROUND: To determine the subtype of HIV-1 of drug users (DUS) in Guangdong Pearl River delta. METHODS: HIV-1 pro-viral DNA from buffy coat of 43 DUS in Guangdong was amplified by nested PCR. The C2-V3 regions of HIV-1 ENV gene was sequenced directly from the PCR product and analyzed. RESULTS: The 43 DUS were confirmed to be infected with four HIV-1 subtype or Circulating Recombinant Form (CRFs): 07-BC(n=29), AE(n=9), 08-BC(n=3) and B(n=2). Genetic distances showed that the AE group was the closest to CM240 strain isolated in Thailand which is mainly circulating in sexually transmitted infector. The 07-BC group was the closest to C54A strain isolated in Northeastern China. The 08-BC group was the closest to 97CNGX-9F strain isolated in Guangxi, China. The B strain was the closest to rl42 strain isolated in Thailand. CONCLUSION: HIV-1 CRFs 07-BC predominates in DUS in Guangdong Pearl River delta.


Assuntos
Genes env , HIV-1 , Sequência de Bases , China , Usuários de Drogas , Infecções por HIV/virologia , HIV-1/genética , Humanos , Dados de Sequência Molecular , Filogenia , Rios , Análise de Sequência
16.
J Chem Phys ; 125(3): 34706, 2006 Jul 21.
Artigo em Inglês | MEDLINE | ID: mdl-16863372

RESUMO

The reaction of a transition metal coordination complex, Ti[N(CH(3))(2)](4), with self-assembled monolayers (SAMs) possessing-OH, -NH(2), and -CH(3) terminations has been examined using supersonic molecular beam techniques. The emphasis here is on how the reaction probability varies with incident kinetic energy (E(i)=0.4-2.07 eV) and angle of incidence (theta(i)=0 degrees -60 degrees ). The most reactive surface is the substrate underlying the SAMs-SiO(2) with a high density of -OH(a) (>5 x 10(14) cm(-2)), "chemical oxide." On chemical oxide, the dynamics of adsorption are well described by trapping, precursor-mediated adsorption, and the initial probability of adsorption depends only weakly on E(i) and theta(i). The dependence of the reaction probability on substrate temperature is well described by a model involving an intrinsic precursor state, where the barrier for dissociation is approximately 0.2-0.5 eV below the vacuum level. Reaction with the SAMs is more complicated. On the SAM with the unreactive, -CH(3), termination, reactivity decreases continuously with increasing E(i) while increasing with increasing theta(i). The data are best interpreted by a model where the Ti[N(CH(3))(2)](4) must first be trapped on the surface, followed by diffusion through the SAM and reaction at the SAMSiO(2) interface with residual -OH(a). This process is not activated by E(i) and most likely occurs in defective areas of the SAM. On the SAMs with reactive end groups, the situation is quite different. On both the-OH and -NH(2) SAMs, the reaction with the Ti[N(CH(3))(2)](4) as a function of E(i) passes through a minimum near E(i) approximately 1.0 eV. Two explanations for this intriguing finding are made-one involves the participation of a direct dissociation channel at sufficiently high E(i). A second explanation involves a new mechanism for trapping, which could be termed penetration facilitated trapping, where the Ti[N(CH(3))(2)](4) penetrates the near surface layers, a process that is activated as the molecules in the SAM must be displaced from their equilibrium positions.

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