Aluminum-based PVD rear-side metallization for front-junction nPERT silicon solar cells

Aluminum-based physical vapor deposition metallization for the rear side of front-junction nPERT silicon solar cells is presented. Single-layer Al metallization is compared with Al-Si (1 at% Si) alloy and multi-layer Al-based metallization in terms of Al-spiking, specific contact resistance and back-side reflection. Al-spiking is observed when a single-layer Al metallization is used. Using an Al-Si alloy metallization, Al-spiking is avoided, however, resulting in a strong Si-precipitation. A novel approach consisting of a multi-layer Al-Si/Al stack instead of single-layer Al or Al-Si alloy metallization is developed. Optimizing the thickness of the Al-Si layer in the Al-Si/Al stack significantly decreases Si-precipitation and suppresses the Al-spiking at the same time. In addition, the optimized Al-Si/Al stack showed sufficiently low specific contact resistance and high back-side reflection and this even with a significantly higher thermal stability than the single-layer Al metallization.Diese Arbeit befasst sich mit Al-basierter physikalischer Gasphasenabscheidung als alternatives Herstellungsverfahren einer Rückseitenmetallisierung für nPERT Siliziumsolarzellen. Al-basierte Metallisierungssysteme wie Al, Al-Si-Legierung (1 at% Si) und Al-Si/Al-Schichtstapel wurden in Bezug auf Al-Spiking, spezifischem Kontaktwiderstand und Rückseitenreflexion untersucht und verglichen. Bei Verwendung einer Al-Einzelschichtmetallisierung kam es zur Bildung von Al-Spikes. Wurde eine Al-Si-Legierung aufgebracht, konnte das Al-Spiking vermieden werden, jedoch gleichzeitig mit einer Bildung von starkausgeprägten Si-Präzipitaten. Deswegen wurde ein neuer Ansatz mit einem Al-Si/Al-Schichtstapel statt Einzelschichtsystemen entwickelt. Mit diesem Ansatz und mit einer optimierten Dicke der Al-Si-Schicht konnten sowohl das Al-Spiking als auch die Si-Präzipitation deutlich reduziert werden. Der optimierte Al-Si/Al-Schichtstapel zeigte zusätzlich einen ausreichend niedrigen spezifischen Kontaktwidestand und eine hohe Rückseitenreflexion und darüber hinaus eine deutlich höhere thermische Stabilität verglichen mit dem Al-Einzelschichtmetallisierung

Uncontrolled Glycemia and High Percentage of Truncal Fat Elevate Levels of CRP and IL-6 Among Patients with Type 2 Diabetes

Background Systemic inflammation is the continuous phenomenon of inflammatory response which can promote tissue damage. Systemic inflammation is characterized by circulatory elevation of many inflammatory mediators such as (CRP, IL-6 and TNF-α). This state plays a pivotal role in all stages of type 2 diabetes. Stages include pathogenicity and progression and chronic complication development. This study aimed at investigating the risk of systemic inflammation among type 2 diabetic patients according to glycemic control. Objectives This work aimed to investigate the risk of systemic inflammation among type 2 diabetic patients in relation to body fat accumulation and distribution among patients with controlled glycaemia versus poorly controlled patients. Subjects/Methods Study protocol and tools were approved by the research ethics committee; Institutional Review Board (IRB) at Jordan University of Science and Technology (JUST). Patients were recruited from out-patient endocrinology unit at King Abdullah University Hospital (KAUH), Jordan University of Science and Technology Health Center and major private endocrinology clinics in North of Jordan. Initial screening included 1500 patients diagnosed with type 2 diabetes. Due to the multiple co-variation nature of the relationship of interest, about 75% of the initially screened patients were excluded from the study. A total of 198 male and female patients diagnosed with type 2 diabetes participated in this cross-sectional. Patients’ weight, height, waist circumference, total body fat and truncal fat percent were measured. Venous blood specimen were collected and levels of HbA1c, serum hs-CRP, serum IL-6 were determined. A 10-ml sample of venous blood was collected from each patient by a registered nurse. HbA1c blood samples collected in Ethylene-Diamine-Tetra-Acetic acid (EDTA) tubes and measured in whole blood using the Immuno-inhibition test for the quantitative determination of glycosylated hemoglobin (Beckman Coulter AU analyzers). Blood samples of hs-CRP and IL-6 collected in Z-Clot activator tubes. Samples were allowed to clot before centrifugation for 15 minutes at 1000 × g. Aliquot of serum stored at ≤ -22°C in a sterile small tubes prior to biochemical assay. Immuno-turbidimetric test was used to determine hs-CRP levels (Beckman Coulter AU analyzers). IL-6 was measured using a human immunoassay kit from R&D SYSTEMS through sandwich-type enzyme-linked immunosorbent assay (ELISA). Absorbance Microplate reader was used to measure the optical density of IL-6 (BioTek ELx800). Anthropometrics (weight, height) were measured following World Health Organization procedures. 18 Body weight was measured with the individuals wearing no shoes and light clothing. Height was measured using measuring rod (Seca, Germany).Body Mass Index (BMI) was calculated using the ratio of weight (kilograms) to the square of height (meters) kg/m2. Waist circumference (WC) was measured to the nearest centimeter using non-stretchable circumference measuring tape (SECA 203, Germany). The site of tape placing was determined according to World Health Organization (WHO) description of middle way between the iliac crest and lower rib border. The WHO BMI cutoff points were used to classify patients based on their BMI and WC. Patients’ total body fat and truncal fat percent were determined using bioelectrical impedence technique (TANITA, BC-418). The Segmental body composition analyzer (TANITA, BC-418) used in this study was previously validated against hydro-densitometry in the assessment of body composition in healthy young adults. Body fat and percentage cut-off points used were gender and age specific based on which patients were classified into healthy, over-fat, and obese. Cut-off points for truncal fat % were gender specific based according to which patients were classified into three levels of truncal fat: low, average, and high. A P-value of < 0.05 was considered the cut-off level for statistical significance. Multivariate analysis of variance (MANOVA) was used to examine the relationship between serum levels of hs-CRP, IL-6 and glycemic control and body fatness, Least Significant Difference (LSD) post-hoc MANOVA was conducted to determine the difference between patients in different categories. Results Poorly controlled females had higher levels of hs-CRP as compared to poorly controlled males (P = 0.004). However, no differences were noticed in the CRP serum levels in good glycemic control group. At the same time, older patients with poor glycemia had higher serum IL-6 levels as compared to younger patients. In poor glycemic control group and after adjusting for age, gender, lipid lowering drugs and diabetes duration, the (hs-CRP) serum levels of patients with high BMI (obese) was significantly higher than that observed in the normal, and overweight patients (P-value = 0.02). Body fat percentage was significantly associated with hs-CRP serum levels inpoor glycemic control group; patients with healthy body fat percentages had lower hs-CRP (6.30 ± 0.66) compared to patients with obese patients (11.89 ± 1.30). Trunk fat mean seems to be significantly associated with patients’ hs-CRP serum levels regardless of the glycemic control groups (P-value = 0.05). Among patients with poor glycemic control, higher levels of serum IL-6 were detected in obese patients (6.10 ± 0.93) compared to those with normal body weight patients (4.06 ± 1.82). Similar trend is found with regard to WC where patients with poor glycemic control continue to have higher levels of IL-6 with higher WC (P = 0.018). Positive relationship was found between IL-6 serum levels and trunk fat percentage among all patients regardless of glycemic control. Conclusion Findings of the current study indicate that high subcutaneous intraperitoneal fat induces the risk of systemic inflammation regardless of glycemic control. General obesity is associated with systemic inflammation only among patients with poor glycemic control. This study had several strengths including the tough selection procedure of the participants to rule out any response to acute response to inflammation. Several blood measurements were performed on the patients including HbA1c, CRP, and IL-6 which add to the validity of our hypothesis testing. Moreover, the study operationalized obesity in different ways BMI, WC, total and truncal fat%. However, findings of this study is limited due to the cross-sectional nature of the study design.qscienc

Elective laparoscopic splenectomy for giant hemangioma: a case report

Although unusual, hemangioma is the most common primary splenic neoplasm. Splenectomy is indicated when the tumor is large, with increased risk of hemorrhage. The laparoscopic approach is preferred for most elective splenectomies. Although technically feasible, laparoscopic splenectomy can be a challenge in the patient with splenomegaly. We present herein a case of an 18-year-old male asymptomatic patient who underwent laparoscopic splenectomy for the incidental finding of splenomegaly caused by a large splenic hemangioma. Laparoscopic splenectomy appears to be a safe and effective procedure, in appropriately experienced hands, for patients with splenomegaly, given the spleen's fragile anatomy and its relationship to other abdominal viscera

Long-term Follow-up of Laparoscopic Splenectomy in Patients with Immune Thrombocytopenic Purpura

Laparoscopic splenectomy (LS) has been reserved for intractable and relapsing immune thrombocytopenic purpura (ITP) despite medical treatment. With further experiences of LS in ITP, we investigated long term outcomes of LS, especially newly developed morbidities, and tried to find predictive factors for favorable outcomes. From August 1994 to December 2004, fifty-nine patients whose follow-up period was more than 12 months after LS were investigated. After a long-term follow-up (median 54 months, range 12.5-129 months), a complete response (CR) was found in 28 patients (47.5%), partial response in 24 (40.7%), and no response in 7 (11.9%). The relapse rate during follow-up periods was 15.2%. The rapid response group (p=0.017), in which the platelet count increased more than twice of the preoperative platelet count within 7 days after LS, relapsing after medical treatment (p=0.02), and the satisfactory group as the initial result of LS (p=0.001) were significant for predicting CR in univariate analysis, but only the initial satisfactory group was an independent predictive factor for CR in multivariate analysis (p=0.036, relative risk=6419; 95% CI, 1.171-35.190). Infections were the most frequent morbidities during the follow-up period, which were treated well without mortality. LS is a safe and effective treatment modality for ITP. Active referral to surgery might be required, considering complications and treatment results related to long-term use of steroid-based medications

Splenic peliosis with spontaneous splenic rupture: report of two cases

BACKGROUND: Peliosis is a rare condition characterised by multiple cyst-like, blood-filled cavities within the parenchyma of solid organs. Most commonly affecting the liver, isolated splenic peliosis is an even more unique phenomenon. Patients with the condition are often asymptomatic. However, this potentially lethal condition can present with spontaneous organ rupture. We present two such cases, discuss their management and review what is currently known in the existing literature. CASE PRESENTATION: A previously well twenty-six year old woman presented with abdominal pain following a trivial episode of coughing. A diagnosis of spontaneous splenic rupture was made following clinical and radiological examination. She underwent emergency splenectomy and made a full, uneventful recovery. Histopathological examination confirmed splenic peliosis. The second case describes an eighty six year old lady who sustained a trivial fall and developed pain in her left side. A CT confirmed splenic rupture. She became haemodynamically unstable during her admission and underwent emergency splenectomy. Histopathological examination revealed splenic peliosis. She went on to make an uneventful recovery. CONCLUSION: Splenic peliosis is very rare. It has a number of associations including immunosuppression, drug therapy and infection. Although patients are often asymptomatic, life-threatening spontaneous organ rupture may occur. If the diagnosis of peliosis is confirmed, additional investigations should be considered to detect its presence in other organs. Furthermore, the presence of the condition may be relevant if further medical or surgical intervention is planned

Laparoscopic versus conventional appendectomy - a meta-analysis of randomized controlled trials

<p>Abstract</p> <p>Background</p> <p>Although laparoscopic surgery has been available for a long time and laparoscopic cholecystectomy has been performed universally, it is still not clear whether open appendectomy (OA) or laparoscopic appendectomy (LA) is the most appropriate surgical approach to acute appendicitis. The purpose of this work is to compare the therapeutic effects and safety of laparoscopic and conventional "open" appendectomy by means of a meta-analysis.</p> <p>Methods</p> <p>A meta-analysis was performed of all randomized controlled trials published in English that compared LA and OA in adults and children between 1990 and 2009. Calculations were made of the effect sizes of: operating time, postoperative length of hospital stay, postoperative pain, return to normal activity, resumption of diet, complications rates, and conversion to open surgery. The effect sizes were then pooled by a fixed or random-effects model.</p> <p>Results</p> <p>Forty-four randomized controlled trials with 5292 patients were included in the meta-analysis. Operating time was 12.35 min longer for LA (95% CI: 7.99 to 16.72, p < 0.00001). Hospital stay after LA was 0.60 days shorter (95% CI: -0.85 to -0.36, p < 0.00001). Patients returned to their normal activity 4.52 days earlier after LA (95% CI: -5.95 to -3.10, p < 0.00001), and resumed their diet 0.34 days earlier(95% CI: -0.46 to -0.21, p < 0.00001). Pain after LA on the first postoperative day was significantly less (p = 0.008). The overall conversion rate from LA to OA was 9.51%. With regard to the rate of complications, wound infection after LA was definitely reduced (OR = 0.45, 95% CI: 0.34 to 0.59, p < 0.00001), while postoperative ileus was not significantly reduced(OR = 0.91, 95% CI: 0.57 to 1.47, p = 0.71). However, intra-abdominal abscess (IAA), intraoperative bleeding and urinary tract infection (UIT) after LA, occurred slightly more frequently(OR = 1.56, 95% CI: 1.01 to 2.43, p = 0.05; OR = 1.56, 95% CI: 0.54 to 4.48, p = 0.41; OR = 1.76, 95% CI: 0.58 to 5.29, p = 0.32).</p> <p>Conclusion</p> <p>LA provides considerable benefits over OA, including a shorter length of hospital stay, less postoperative pain, earlier postoperative recovery, and a lower complication rate. Furthermore, over the study period it was obvious that there had been a trend toward fewer differences in operating time for the two procedures. Although LA was associated with a slight increase in the incidence of IAA, intraoperative bleeding and UIT, it is a safe procedure. It may be that the widespread use of LA is due to its better therapeutic effect.</p

Initial Experiences with Laparoscopy-assisted and Total Laparoscopy for Anatomical Liver Resection: A Preliminary Study

Although laparoscopic surgery has become more popular, its technical difficulties have limited the applications of this technique to liver surgery. We report here on our experience with liver resection with using the laparoscopy-assisted (Lap-Assist) and total laparoscopic (Total-Lap) methods. From April 2001 to June 2003, a total of 20 laparoscopic anatomical resections of the liver were retrospectively reviewed. These were comprised of 10 cases in which the Lap-Assist method was used (these were performed during the early study period), and 10 cases in which the Total-Lap was used (these were done in the later study period). In the Lap-Assist group, the following resections were performed: 7 cases of left lateral sectionectomy, a case of left hemihepatectomy, a case of right hemihepatectomy and a case of open conversion. In the Total-Lap group, 6 cases of left hemihepatectomy and 4 cases of left lateral sectionectomy were performed. The sizes of the incisions were 8.7 cm and 4.6 cm, respectively, (p=0.000). There were no differences in the operation times, the transfusion amounts, the starting days of the patients' diets, the complication rates or the durations of the hospital stay between the two groups. Both the laparoscopy-assisted method and the total laparoscopic method are feasible to use for performing anatomical liver resection