SIFAT HIDROPHOBIK ISOLASI RESIN EPOKSI DENGAN BAHAN PENGISI ALUMINA, PASIR SILIKA DAN FIBER GLASS

Isolator adalah alat yang berfungsi sebagai isolasi dan pemegang mekanis dari perlengkapan atau penghantar yang dikenai beda potensial. Jika isolator gagal dalam kegunaannya memisahkan antara dua saluran maupun saluran dengan pentanahan maka penyaluran energi tersebut akan tidak optimal. Pengaruh keadaan udara di sekitarnya dan polutan yang menempel pada permukaan isolator yang menyebabkan permukaan isolator bersifat konduktif. Dalam melayani suatu sistem tenaga listrik, ada beberapa hal yang perlu diperhatikan dan dipertimbangkan dalan pembuatan isolator yaitu, sifat-sifat dari kandungan material sebagai bahan dasar untuk membuat isolator, kemampuannya pada cuaca buruk, keadaan saat terkontaminasi serta pertimbangan masalah biaya produksi. Isolator akan mengalami pemburukan dalam penggunaannya. Pemburukan isolator disebabkan karena sinar UV, pengembangan pembekuan dari polutan. Karena pemburukan itu maka kinerja dari isolator akan berkurang.. Dalam penelitian ini bahan uji memiliki ukuran 70 X 70 X 5 mm, dan bahan tersebut merupakan campuran dari (DGEBA) dan methaphenylene diamine (MPDA) dan bahan pengisi berupa pasir silika,alumina dan fiber glass perbandingan campuran dari bispenol A dengan MPDA adalah 1:1, sedangkan sebagai filler mulai dari 10%, 20%, 30%, 40%, 50% dengan lama penyinaran UV bervariasi 0 sampai 96 jam. Dari penelitian ini didapat nilai ESDD dan besar sudut kontak. Dari hasil pengukuran sudut kontak hanya ada dua bahan isolator yang yang bersifat hidrophobik yaitu fiber glass 50% UV 36 jam dan alumina 30% UV 12 jam dan yang lain masih bersifat partially weatted ( basah sebagian ). Secara keseluruhan ternyata bahan isolasi berpengisi fiber glass lebih tinggi nilai sudut kontaknya dibandingkan pasir silika dan alumina, maka, perlu dicari cara agar proses pembuatan bahan uji terbebas dari adanya void dan perlunya pembuatan isolator dari bahan yang tahan terhadap air

Giant magnetocaloric effect in Gd2NiMnO6 and Gd2CoMnO6 ferromagnetic insulators

We have investigated magnetocaloric effect in double perovskite Gd2NiMnO6 (GNMO) and Gd2CoMnO6 (GCMO) samples by magnetic and heat capacity measurements. Ferromagnetic ordering is observed at ~130 K (~112 K) in GNMO (GCMO), while the Gd exchange interactions seem to dominate for T < 20 K. In GCMO, below 50 K, an antiferromagnetic behaviour due to 3d-4f exchnage interaction is observed. A maximum entropy (-{\Delta}SM) and adiabatic temperature change of ~35.5 J Kg-1 K-1 (~24 J Kg-1 K-1) and 10.5 K (6.5 K) is observed in GNMO (GCMO) for a magnetic field change of 7 T at low temperatures. Absence of magnetic and thermal hysteresis and their insulating nature make them promising for low temperature magnetic refrigeration

Tetramer Orbital-Ordering induced Lattice-Chirality in Ferrimagnetic, Polar MnTi2O4

Using density-functional theory calculations and experimental investigations on structural, magnetic and dielectric properties, we have elucidated a unique tetragonal ground state for MnTi2O4, a Ti^{3+} (3d^1)-ion containing spinel-oxide. With lowering of temperature around 164 K, cubic MnTi2O4 undergoes a structural transition into a polar P4_1 tetragonal structure and at further lower temperatures, around 45 K, the system undergoes a paramagnetic to ferrimagnetic transition. Magnetic superexchange interactions involving Mn and Ti spins and minimization of strain energy associated with co-operative Jahn-Teller distortions plays a critical role in stabilization of the unique tetramer-orbital ordered ground state which further gives rise to lattice chirality through subtle Ti-Ti bond-length modulations

メチル化CpG結合ドメインによるDNAおよびタンパク質認識の構造学的研究

京都大学新制・課程博士博士(工学)甲第25304号工博第5263号京都大学大学院工学研究科分子工学専攻(主査)教授 佐藤 啓文, 教授 森 泰生, 教授 跡見 晴幸学位規則第4条第1項該当Doctor of Philosophy (Engineering)Kyoto UniversityDGA

Vigorous Exercise Effect on Cardiovascular Health

Many studies examine the effects of vigorous cardiovascular exercise on the heart. Intense exercise causes frequent muscle contractions in the heart and specific biomarkers that usually signify a myocardial infarction are released into the bloodstream. However, studies indicate that there might not be a correlation between the release of biomarkers and cardiac function. Another study shows that long term vigorous exercise negatively affects the heart by dramatically increasing the mass and volume of the right and left ventricles, thereby resulting in hypertrophy. The cardiac hypertrophy is still evident even after the subjects have stopped exercising. Cardiac hypertrophy results in myocardial fibrosis and scarring. The percent of myocardial fibrosis in those engaging in long term vigorous exercise was significantly higher than that of the control group. After intense training, tests found a reduced right ventricle ejection fraction due to dilation of the right ventricle while there was no dilation in the left ventricle. In addition, a correlation was found between reduced right ventricle ejection fraction and ventricle arrhythmias. The mortality rate of vigorous exercisers was slightly higher in comparison to those who moderately exercised. Animal studies showed that rats who exercised developed left ventricle hypertrophy, impaired diastolic function, and right ventricle dilation, the symptoms found in humans with an “athlete’s heart.” Additional research on the effect of vigorous exercise on the heart needs to be conducted to verify these findings

Bounding Betti Numbers of Sets Definable in O-Minimal Structures Over the Reals

A bound for Betti numbers of sets definable in o-minimal structures is presented. An axiomatic complexity measure is defined, allowing various concrete complexity measures for definable functions to be covered. This includes common concrete measures such as the degree of polynomials, and complexity of Pfaffian functions. A generalisation of the Thom-Milnor Bound for sets defined by the conjunction of equations and non-strict inequalities is presented, in the new context of sets definable in o-minimal structures using the axiomatic complexity measure. Next bounds are produced for sets defined by Boolean combinations of equations and inequalities, through firstly considering sets defined by sign conditions, then using this to produce results for closed sets, and then making use of a construction to approximate any set defined by a Boolean combination of equations and inequalities by a closed set. Lastly, existing results for sets defined using quantifiers on an open or closed set are generalised, using a construction from Gabrielov and Vorobjov to approximate any set by a compact set. This results in a method to find a general bound for any set definable in an o-minimal structure in terms of the axiomatic complexity measure. As a consequence for the first time an upper bound for sub-Pfaffian sets defined by arbitrary formulae with quantifiers is given. This bound is singly exponential if the number of quantifier alternations is fixed.Comment: 82 page, PhD thesi

An analytical study on wound dehiscence and related factors

Wound dehiscence is a significant cause of post operative morbidity. In this study the various factors associated with wound dehiscence were studied. All patients with wound dehiscence post gynecological surgeries in our hospital were evaluated retrospectively for possible risk factors. Major risk factors as per our study include malnutrition,obesity, illiteracy, low socioeconomic status,anemia, diabetesmellitus, blood transfusion, prolonged surgery, emergency procedures. Most of these factors were preventable or modifiable at a primary level.