Ink Material Selection and Optical Design Considerations in DLP 3D Printing.

Digital light processing (DLP) 3D printing has become a powerful manufacturing tool for the fast fabrication of complex functional structures. The rapid progress in DLP printing has been linked to research on optical design factors and ink selection. This critical review highlights the main challenges in the DLP printing of photopolymerizable inks. The kinetics equations of photopolymerization reaction in a DLP printer are solved, and the dependence of curing depth on the process optical parameters and ink chemical properties are explained. Developments in DLP platform design and ink selection are summarized, and the roles of monomer structure and molecular weight on DLP printing resolution are shown by experimental data. A detailed guideline is presented to help engineers and scientists to select inks and optical parameters for fabricating functional structures for multi-material and 4D printing applications.

Is a Clean Development Mechanism project economically justified? Case study of an International Carbon Sequestration Project in Iran.

The present study evaluates a carbon sequestration project for the three plant species in arid and semiarid regions of Iran. Results show that Haloxylon performed appropriately in the carbon sequestration process during the 6 years of the International Carbon Sequestration Project (ICSP). In addition to a high degree of carbon dioxide sequestration, Haloxylon shows high compatibility with severe environmental conditions and low maintenance costs. Financial and economic analysis demonstrated that the ICSP was justified from an economic perspective. The financial assessment showed that net present value (NPV) (US$1,098,022.70), internal rate of return (IRR) (21.53%), and payback period (6 years) were in an acceptable range. The results of the economic analysis suggested an NPV of US$4,407,805.15 and an IRR of 50.63%. Therefore, results of this study suggest that there are sufficient incentives for investors to participate in such kind of Clean Development Mechanism (CDM) projects.

Effectiveness of silica-lasing method on the bond strength of composite resin repair to Ni-Cr alloy.

PURPOSE: The aim of this study was to evaluate the effectiveness of silica-lasing method for improving the composite resin repair of metal ceramic restorations. MATERIALS AND METHODS: Sixty Ni-Cr cylindrical specimens were fabricated. The bonding surface of all specimens was airborne-particle abraded using 50 µm aluminum oxide particles. Specimens were divided into six groups that received the following surface treatments: group 1-airborne-particle abrasion alone (AA); group 2-Nd:YAG laser irradiation (LA); group 3-silica coating (Si-CO); group 4-silica-lasing (metal surface was coated with slurry of opaque porcelain and irradiated by Nd:YAG laser) (Si-LA); group 5-silica-lasing plus etching with HF acid (Si-LA-HF); group 6-CoJet sand lased (CJ-LA). Composite resin was applied on metal surfaces. Specimens were thermocycled and tested in shear mode in a universal testing machine. The shear bond strength values were analyzed using ANOVA and Tukey's tests (α = 0.05). The mode of failure was determined, and two specimens in each group were examined by scanning electron microscopy and wavelength dispersive X-ray spectroscopy. RESULTS: Si-CO showed significantly higher shear bond strength in comparison to other groups (p < 0.001). The shear bond strength values of the LA group were significantly higher than those of the AA group (p < 0.05). No significant difference was found among lased groups (LA, Si-LA, Si-LA-HF, CJ-LA; p > 0.05). The failure mode was 100% adhesive for AA, Si-LA, Si-LA-HF, and CJ-LA. LA and Si-CO groups showed 37.5% and 87.5% cohesive failure, respectively. CONCLUSION: Silica coating of Ni-Cr alloy resulted in higher shear bond strength than those of other surface treatments.

Wnt5a influences viability, migration, adhesion, colony formation, E- and N-cadherin expression of human ovarian cancer cell line SKOV-3.

Epithelial ovarian cancer (EOC) cells express Wnt5a, but its role in ovarian cancer progression is poorly defined. The aims of the present study were two-fold: 1) to determine the Wnt5a role in viability, apoptosis, migration, colony formation and adhesion of human serous epithelial ovarian cancer cell line SKOV-3, and 2) to assess the relationship of Wnt5a with E- and N-cadherin in high- and low-grade human serous ovarian cancer specimens. Wnt5a over-expression led to 29% increased serum-independent cell viability (P < 0.05) and 35% decreased caspase-3 activity (P < 0.01) compared to SKOV-3 cells. There was 96% (P < 0.001) increased cell motility in Wnt5a-transfected SKOV-3 (SKOV-3/Wnt5a) cells compared to SKOV-3, which was abrogated in the presence of JNK inhibitor. In addition, there was about 42% increased cell adhesion to Matrigel compared to SKOV-3 cells (P < 0.001). Colony-forming assay showed a 4.4-fold increased colony formation in SKOV-3/Wnt5a cells compared to SKOV-3 cells (P < 0.001). E- and N-cadherin levels were reduced by 49 % and 67 % in SKOV-3/Wnt5a cells compared to mock cells, respectively. Wnt5a and E-cadherin immunoexpression was significantly (P < 0.001) different in low-grade serous ovarian cancer (LGSC) and high-grade serous ovarian cancer (HGSC). In HGSC specimens, strong immunoexpression of Wnt5a was detected compared to LGSC. However, E-cadherin showed moderate immunostaining (84 %) in HGSC, whereas 100 % of LGSC specimens showed strong immunoexpression. In both groups no N-cadherin immunoexpression was detected. Moreover, Wnt5a showed a positive relationship with E-cadherin in the LGSC group (r = 0.661, P = 0.027). These results may support important roles for Wnt5a in EOC progression.

Influence of different power outputs of intraoral Nd:YAG laser on shear bond strength of a resin cement to nickel-chromium dental alloy.

Up to now, there is no any experience about the application of dental lasers to bond resin composites to metal surfaces in dentistry. The aim of this preliminary study was to evaluate if the laser irradiation of ceramic-covered alloy surface would improve the bond strength of resin to metal, and if different parameters of laser output may influence the strength of this bond. Fifty three cylinders (thickness of 5 mm and diameter of 10 mm) were made up of a commercially available nickel-chromium alloy by lost-wax technique. Forty prepared specimens were divided into four groups. Five specimens in each group were covered by slurry of dental opaque porcelain and irradiated by Nd:YAG laser using different output parameters for each group. Other five specimens in each group were treated using the same laser parameters without porcelain covering. Five sandblasted specimen served as control group. Panavia F2.0 was bonded on the metal surfaces using polyethylene tubes. In ceramic-coated specimens, silane was applied to achieve chemical bond between silica particles and resin cement. All specimens were thermocycled and subjected to shear bond strength (SBS) test (50 kgf at 0.5 mm/min). Two specimens of each ceramic-coated laser-treated groups were studied using scanning electron microscopy and wavelength dispersive X-ray spectroscopy which showed stabilization of silica particles on the metal surface. ANOVA procedure showed that although shear bond strength was significantly higher in porcelain-covered laser treated samples, but the effect of power output of laser irradiation was not significant (P = 0.917). There were no statistically significant difference between SBS in control samples and laser treated specimens without porcelain covering. It can be concluded that Nd:YAG laser surface treatment may improve the silica coating of alloy surface to achieve better resin-metal bond.

Tensile bond strength of sealants following Er:YAG laser etching compared to acid etching in permanent teeth.

The aim of this in vitro study was to assess the effect of Er:YAG laser surface treatment on the tensile bond strength of a sealant in permanent teeth. A total of 30 sound third molars were selected and embedded in cold-cure acrylic resin. The enamel surfaces were flattened by a grinding. The teeth were randomly divided into three groups and pretreated as follows: (1) 37% phosphoric acid; (2) Er:YAG laser (1.5 ml/min water spray, 100 mJ energy output, 10 Hz frequency, focal distance 17 mm); (3) Er:YAG laser + 37% phosphoric acid. The treated surfaces were isolated by double adhesive Sellotape and after insertion of a split Teflon matrix at an isolated site, sealant was applied. The specimens were thermocycled and stored at 37°C in distilled water for 72 h, then subjected to a tensile bond strength test (50 kgf at 0.5 mm/min). The mean tensile bond strengths (± SD, in megapascals) were: 18.51 ± 5.68 in group 1, 8.06 ± 2.69 in group 2, and 17.33 ± 5.04 in group 3. Data were submitted to analysis of variance and the Tukey test. No significant difference were found between groups 1 (37% phosphoric acid) and group 3 (Er:YAG laser + 37% phosphoric acid) but treatment with the Er:YAG laser alone (group 2) resulted in significantly lower tensile bond strength than seen in the other groups. In this setting, the Er:YAG laser prepared the enamel surface for sealing but did not eliminate the need for acid etching before sealant application.

Tea polyphenols and theaflavins are present in prostate tissue of humans and mice after green and black tea consumption.

Green and black tea have shown promise in the chemoprevention of prostate cancer. The objective of this study was to determine the bioavailability and bioactivity of tea polyphenols (PP) and theaflavins in human serum and human and mouse tissues. A decaffeinated black tea diet was administered to C57BL/6 mice. PPs and theaflavins were found in the small and large intestine, liver, and prostate in conjugated and free forms. The relative prostate bioavailability of theaflavin was 70% higher than that of epigallocatechin gallate (EGCG). In the second mouse study, a green tea (GT) diet was administered followed by the control diet for 1-5 d. Epicatechin (EC), EGCG, and epicatechin gallate (ECG) concentrations in prostate tissue were significantly decreased after 1 d of consuming the control diet. Epigallocatechin gallate (EGC), however, did not decrease significantly. For the human study, 20 men scheduled for surgical prostatectomy were randomly assigned to consume 1.42 L daily of GT, BT, or a caffeine-matched soda control (SC) for 5 d before radical prostatectomy. Tea PPs were greater in prostate samples from men consuming BT and GT than in men consuming SC (P = 0.0025). Although tea PP were not detectable in serum, ex vivo LNCaP prostate cancer cell proliferation was less when cells were grown in media containing patient serum collected after BT (P < 0.001) and GT (P = 0.025) consumption relative to baseline serum This is the first human study to show that tea polyphenols and theaflavins are bioavailable in the prostate where they may be active in the prevention of prostate cancer.

Expression of retinoid receptors in sebaceous cell carcinoma.

PURPOSE: The aim of this study is to investigate whether there are any abnormalities in the in vivo expression of retinoid acid receptors (RAR-alpha, RAR-beta and RAR-gamma) and retinoid X receptors (RXR-alpha, RXR-beta and RXR-gamma) in sebaceous cell carcinoma. METHODS: Expression of retinoid receptors in paired specimens of cancerous tissues (n = 10) and adjacent normal tissues (n = 10) from 10 patients with sebaceous cell carcinoma was studied immunohistochemically by using anti-retinoid receptor antibodies. RESULTS: In eight of the 10 normal tissue samples, all six receptors were expressed. In the other two samples, all receptors were expressed except RAR-gamma (one sample) or RXR-gamma (two samples). Five tumours (50%) lacked RAR-alpha; RAR-alpha expression was lower in tumours than in normal tissues in eight of 10 cases. RAR-beta was expressed in the cytoplasm of nine of 10 tumours; RAR-beta expression was at least as high in tumours as in normal tissue in eight of 10 cases. Two tumours lacked RAR-gamma; three tumours had lower RAR-gamma expression than paired normal epithelium; four had the same RAR-gamma expression, and one had higher RAR-gamma expression. RXR-alpha expression was strong in all normal tissues and tumour samples. Ten tumours lacked RXR-beta and all 10 tumours lacked RXR-gamma expression. CONCLUSIONS: Diminished RXR-beta and RXR-gamma expression might be related to the development of sebaceous cell carcinoma. Additional studies are required to establish whether the defects in RAR expression in sebaceous cell carcinoma might affect the potential response of this tumour to treatment with retinoids.

Retinoid receptor subtypes in sebaceous cell carcinoma of the eyelid.

PURPOSE: To study retinoid receptor expression in sebaceous cell carcinoma of the eyelid. METHODS: Expression of retinoid receptors (RAR alpha, beta, and gamma and RXR alpha, beta, and gamma) in tumor specimens from 10 patients with sebaceous cell carcinoma of the eyelid and in 3 normal incidental tarsus specimens from healthy adults without cancer was studied immunohistochemically by using antiretinoid receptor antibodies. RESULTS: In all 3 specimens of normal tarsus, all 6 retinoid receptors were expressed. RARalpha expression was absent in 3 tumors and was decreased in 3 tumors compared with expression in the control tissues. RARbeta expression in carcinomas was primarily perinuclear; 6 tumors showed increased RARbeta expression compared with controls. RARgamma expression was absent in 4 tumors and was decreased in 2 tumors compared with controls. RXRalpha nuclear expression was decreased compared with controls in 5 tumors. RXRbeta expression was low in 7 tumors. RXRgamma expression was absent in 6 tumors. CONCLUSIONS: Aberrant expression of retinoid receptors in sebaceous cell carcinoma of the eyelid might play a role in the pathogenesis and progression of this carcinoma.

Growth factor receptor expression in orbital lymphangioma: possible therapeutic implications.

OBJECTIVE: To examine the expression of molecules targeted by imatinib mesylate (STI571;Gleevec) and epidermal growth factor receptor (EGFR) inhibitors in orbital lymphangiomas. DESIGN: Retrospective observational case series. PARTICIPANTS: Six patients with orbital lymphangioma treated at four institutions between March 2000 and December 2002. METHODS: Tissue specimens and medical records from six patients were collected. Immunohistochemical analysis was performed using antibodies against c-kit and platelet-derived growth factor receptor (PDGFR) alpha and beta and EGFR tyrosine kinase.