Duration of load effects on development of deformations in bolted moment connection

Experience saved in the construction industry shows that the timber portal frames with semi-rigid connections at knee joint exhibit permanently increase displacements at the knee and apex point. Normally, timber portal frame with semi-rigid knee joint connection is made with mechanical fasteners located in double circles and cannot be designed without relevant rotation at connection during structures’ exploitation time. The only way to increase connection rigidity is to rise distance from fasteners location at connection, but at the same time, the tension and shear stress become significant at the external section of members. The previous experience is obtained by a model testing showing that deformations at semi-rigid connections are non-linear. These were tests under short-term load and did not disclose creep effects, which can be significant. This study is aimed at the examination of increasing deformations with time under constant static load (creep effects) in semi-rigid dowelled connection. Experimental test models were made and set under long-term load in controlled environmental conditions (heated laboratory room). Results show a significant creep influence to decrease connection stiffness. Corresponding numerical test of orthotropic 3d model by Dlubal RFEM software tools was performed analyzing the value of expected deformations. Results of the numerical test showed that friction between timber elements and extra nuts on bolts can increase connection stiffness. Research results in this stage show that the creep can affect connection stiffness more than expected. Also, experimental test results showed lower deformation values comparing with the ones obtained by the numerical test.

PENGTINGNYA PARTISIPASI WALI MURID DALAM MENINGKATKAN MINAT BELAJAR SISWA

Things that have little role and meaning in this education problem are the roles and participation of parents in the family. As one part of the educational institution that has the first and foremost predicate, families should be a good opportunity to catch up with children in school or can also be used as additional momentum to understand and clarify material from school. Thus the role of parents in this problem is very large. As part or component of the education system, guardians of students and the community in general are entitled to develop their participation in the advancement of education. In the development of children's learning interest and many are influenced by several by several factors, both internal and external factors. Participation of guardian students is included in the external section which has important values in efforts to increase children's learning interest. The participation of guardian students can be useful in increasing students' interest in learning, this can be seen from the emergence of encouragement of children to study hard, easy and easy for students to solve the difficulties they face and as a medium for success in learning.

Peripherally Inserted Central Catheters (PICCs) Implantation in the Clinical Management of Oncohematologic Patients: Results of a Large Multicenter, Retrospective Study of the REL Group (Rete Ematologica Lombarda - Lombardy Hematologic Network, Italy)

Background: PICCs are vascular devices inserted from a peripheral vein of the upper third of the arm under ultrasound guide, and provide a central venous access (CVA) with an intermediate duration between short term central venous catheters (CVCs), such as jugular or subclavian CVCs, and long term ones (port-a-caths). PICC insertion is ease and safe with no pneumothorax or hemothorax risk. Their extremity reaches a central vein, and can be used for cytostatic drugs, hyperosmolar solutions, and antibiotics infusion. Furthermore, patients (pts) at high risk of hemorrhage for thrombocytopenia or coagulopathy are eligible for PICC insertion. Nevertheless, some concern exists about the risk of infectious and thrombotic complications associated with PICC use in immunocompromised cancer pts characterized by a prothrombotic state. In particular, few clinical data from large oncohematologic pts series are available on PICCs' implants and their complications. Aims: To analyze the results of a large multicenter, retrospective study of the REL group (Rete Ematologica Lombarda-Lombardy Hematologic Network, Italy) aimed at clinically characterizing PICC use in oncohematologic patients management. Methods: Four REL Hematology Centers participate to the study. The clinical data of 453 implanted PICCs from January 2010 to June 2015, were retrospectively collected, for a total of 44,577 catheter days. Pts median age was 61 yrs (range 10-88). Patients' diagnoses were 197 non-Hodgkin's lymphoma, 10 chronic lymphocytic leukemia, 105 acute myeloid leukemia, 45 acute lymphoblastic leukemia, 33 Hodgkin's lymphoma, 39 multiple myeloma, 12 myelodysplastic/myeloproliferative syndrome, 6 miscellaneous. All pts received intravenous chemotherapy, long term anti infectious drugs (antibiotics and antifungals), and hypertonic solutions. PICCs were inserted by ultrasound-guided puncture of a peripheral vein of the arm, by microintroducer technique, under strict asepsis. Chest X-ray was performed to verify correct tip location (ideally in the proximity of cavo-atrial junction). Data on PICCs' lumen number are available in 423 cases: 292 (69%) were single-lumen and 131 were double-lumen (31%). Results: Median PICC life-span was 90 days (range 1-760, Kaplan-Meier method). No major insertion-related complications were observed. Late complications occurred in 172/453 PICCs (38%, 3.8/1000 catheter days): 93 infectious (20%, 2/1000 catheter days), 38 thrombotic (8%, 0.8/1000 catheter days), 37 mechanical (8%, 0.8/1000 catheter days), 5 (1%, 0.1/1000 catheter days) miscellaneous complications (patient intolerance, local pain and hematoma). Among infectious complications, we reported 24 cases (5%, 0.5/1000 catheter days) of fever of unknown origin (FUO) and 69 (15%, 1.5/1000 catheter days) catheter-related bloodstream infections. Mechanical complications consisted of 3 (1%) catheter dislocations, 19 accidental removals (4%), 16 (3%) lumen occlusions and 3 (1%) breakages of the external section of PICC. In 376/453 (83%) cases PICC was removed due to end of intravenous therapy in 160 patients (35%), death in 98 (22%) and to various complications in 118 (26%) cases. Specifically, FUO lead to PICC removal in 10 (2%), infection in 40 (9%), venous thrombosis in 25 (5%) cases, catheter dislocation or accidental removal in 22 (5%), lumen occlusion in 13 (3%), breakage of the external section of PICC in 2 (0,5%), other mechanical complication in 4 (1%), local pain and miscellaneous 2 (0,5%) each. In the case of a complication occured, the incidence of PICC removal was 68% (118/172): FUO/infections represented the removal cause in 50/172 (29%), mechanical complications in 40/172 (23%), thrombosis in 25/172 (14%) cases. Conclusions: Traditional CVCs are associated with significant complications, reported at varying frequencies in highly heterogeneous oncohematologic pts series: infections are reported from 4.6 to 23% and thromboses from 1.2 to 30.2% of the cases. We have clinically characterized a large series of PICCs in oncohematologic patients. Our data suggest that their implant, as an alternative to traditional CVCs, is a safe and effective way to provide oncohematologic patients at high risk of hemorrhagic and infective complications with a CVA. PICCs compare favorably with traditional CVCs reported complications, and facilitate the proper management of complex and prolonged therapeutic programs. Disclosures No relevant conflicts of interest to declare.

SEM and AFM Studies on the Surface and Cross Section Morphology of Rayon-Based Activated Carbon Fibers

The surface and cross section morphology of rayon-based carbon fibers (RCF) and the resulting rayon-based activated carbon fibers (RACF) were investigated through scanning electron microscopy and atomic force microscopy. It was found that the surface of RCF exhibited grooves and striations with the width ranging from 30 to 90 nm, and the striation distribution was about 25 bars per µm around the circumference. While on the RACF, lots of pores emerged on the surface and superficial cross section (about 1 ~ 2 µm to the surface), namely, the external section was porosity but the interior section was close-grained. It was detected that the pore sizes ranged from 50 to 550 nm and the approximate pore distribution was 10 pores in 1×1 µm2. Furthermore, the walls of pores were not smooth but consisted of continuous grains with the diameters about 30 nm.