Phase Behavior of Polyelectrolyte-Surfactant Complexes at Planar Surfaces

We investigate theoretically the phase diagram of an insoluble charged surfactant monolayer in contact with a semi-dilute polyelectrolyte solution (of opposite charge). The polyelectrolytes are assumed to have long-range and attractive (electrostatic) interaction with the surfactant molecules. In addition, we introduce a short-range (chemical) interaction which is either attractive or repulsive. The surfactant monolayer can have a lateral phase separation between dilute and condensed phases. Three different regimes of the coupled system are investigated depending on system parameters. A regime where the polyelectrolyte is depleted due to short range repulsion from the surface, and two adsorption regimes, one being dominated by electrostatics, whereas the other by short range chemical attraction (similar to neutral polymers). When the polyelectrolyte is more attracted (or at least less repelled) by the surfactant molecules as compared with the bare water/air interface, it will shift upwards the surfactant critical temperature. For repulsive short-range interactions the effect is opposite. Finally, the addition of salt to the solution is found to increase the critical temperature for attractive surfaces, but does not show any significant effect for repulsive surfaces.Comment: 23 pages, 10 figure

The Effect of Toluene Solution on the Hydrogen Absorption of the Mg-Ti Alloy Prepared by Synthetic Alloying

The synthesis and characterization of the Mg–Ti alloy have been carried out through a mechanical alloying technique under toluene solution. The Mg and Ti powders are milled for 10, 20, and 30 h in a high energy ball mill. The milled alloys are then hydrided at a temperature of 300 oC in order to investigate the possibility used for hydrogen storage materials. The refinement analyses of the x-ray diffraction patterns show that mechanical alloying of the Mg–Ti powders under toluene solution results in the formation of the TiH2 and Mg2Ti phases. Quantitative analyses indicate that the mass fractions of the TiH2 and Mg2Ti phases are 62.90 % and 30.60 %, while the value for Mg and Ti amount to 2.6 wt% and 1.25 wt%. On hydriding at a temperature of 300 oC, the milled powders are transformed into Mg2TiH4, TiH2 and γ-MgH2 phases with the mass fractions of 25.48 wt%, 64.0 wt%, and 10.52 wt%, respectively. Microstructure analyses show that before milling the shape of particle is mostly a ball shape, after 30 h of milling the shape of particles changes into polygonal shape, and upon hydriding the shape of particles changes from a polygonal shape into an irregular one. The final composition of the specimen after hydriding exhibits that Mg-Ti alloy can be promoted as a hydrogen storage material.Received: 27 January 2009; Revised: 19 November 2009; Accepted: 24 November 200

Safe Food Handling Knowledge, Attitude and Practice of Food Handlers in Hospital Kitchen

Hospital food hygiene plays an important role to patient's health. Studies proved that improper practices and lack of knowledge are contributing factors of foodborne diseases. This study was conducted to determine knowledge, attitude and practice of hospital safe food handling in Semarang, Central Java. A cross sectional study was conducted in two general hospitals' kitchen. Data were collected from 60 food handlers through validated questionnaire. Respondents were grouped into two categories: a. Teaching Hospital, and b.Non-teaching Hospital. Data were collected in February-April 2017. Most of food handlers (80%) were graduated from vocational senior high school (SMK). Respondent's age were 28-37 years (36.7%) in average. Most of respondent‟s work experience (85%) was less than 15 years. The result showed that more than 80% of food handlers have good knowledge in safe food handling procedures, good attitude (66%) and good practices (90%). There was no significant difference of knowledge, attitude and practices between two groups. Results strongly emphasize the need of food hygiene training of hospital food handlers. It also suggest that non food handlers such as nurse or kitchen supervisor should involved in the training. Some aspects of food handlers' safety behavior need to be emphasized

The Effect of Toluene Solution on the Hydrogen Absorption of the Mg-Ti Alloy Prepared by Synthetic Alloying

The synthesis and characterization of the Mg–Ti alloy have been carried out through a mechanical alloying technique under toluene solution. The Mg and Ti powders are milled for 10, 20, and 30 h in a high energy ball mill. The milled alloys are then hydrided at a temperature of 300 oC in order to investigate the possibility used for hydrogen storage materials. The refinement analyses of the x-ray diffraction patterns show that mechanical alloying of the Mg–Ti powders under toluene solution results in the formation of the TiH2 and Mg2Ti phases. Quantitative analyses indicate that the mass fractions of the TiH2 and Mg2Ti phases are 62.90 % and 30.60 %, while the value for Mg and Ti amount to 2.6 wt% and 1.25 wt%. On hydriding at a temperature of 300 oC, the milled powders are transformed into Mg2TiH4, TiH2 and γ-MgH2 phases with the mass fractions of 25.48 wt%, 64.0 wt%, and 10.52 wt%, respectively. Microstructure analyses show that before milling the shape of particle is mostly a ball shape, after 30 h of milling the shape of particles changes into polygonal shape, and upon hydriding the shape of particles changes from a polygonal shape into an irregular one. The final composition of the specimen after hydriding exhibits that Mg-Ti alloy can be promoted as a hydrogen storage material.Received: 27 January 2009; Revised: 19 November 2009; Accepted: 24 November 200

Video Mixer yang Dapat Diprogram

Perkembangan teknologi yang semakin pesat memberi kesempatan untuk mengembangkan berbagai aplikasi elektronika. Di antara perkembangan tersebut adalah suatu piranti yang dapat mengontrol output video yang diinginkan dari beberapa input video. Piranti ini didasarkan pada suatu kebutuhan dalam dunia multimedia, yaitu di antaranya video mixer. Kebutuhan tersebut muncul karena pada umumnya pada suatu event digunakan beberapa kamera video yang secara langsung pada layar Liquid Crystal Display (LCD). Pada aplikasi ini digunakan empat input video dan output video. Untuk melakukan seleksi terhadap video digunakan rangkaian untuk memilih input video yang ingin untuk ditampilkan. Selain secara manual, pemilihan input video dapat dilakukan secara otomatis dengan menggunakan mikrokontroler. Proses mixing yang dilakukan adalah melakukan control intensitas dari sinyal video. Dalam penelitian ini alat video mixer yang dapat diprogram telah direncanakan, dibuat, dan diuji bekerja dengan baik sesuai dengan fungsinya

Needles in a haystack: screening and healthcare system evidence for homelessness

Effectiveness of screening for homelessness in a large healthcare system was evaluated in terms of successfully referring and connecting patients with appropriate prevention or intervention services. Screening and healthcare services data from nearly 6 million U.S. military veterans were analyzed. Veterans either screened positive for current or risk of housing instability, or negative for both. Current living situation was used to validate results of screening. Administrative evidence for homelessness-related services was significantly higher among positive-screen veterans who accepted a referral for services compared to those who declined. Screening for current or risk of homelessness led to earlier identification, which led to earlier and more extensive service engagement