MOHAMMAD IQBAL and R. E. VERRALL. Can. J. Chem. 67, 727 (1989). Apparent molar adiabatic compressibilities and volumes of aqueous solutions of the following drugs (sodium salicylate, methyl orange, L-tryptophan, phenol, and the hydrochloride salts of propranalol, procaine, pilocarpene, and ephedrine) have been calculated from high precision density and sound velocity measurements at 25°C. These drugs are considered important in several biochemical phenomena such as anomalous protein binding, anesthesia, or unique structure-activity relationship and this study is part of a comprehensive investigation of drug-protein interactions in biological systems. The data are qualitatively interpreted in terms of solute-solvent and solute-solute interactions. Some plausible modes of drug hydration are discussed with particular reference to the structure of the drug molecules. The adiabatic compressibility shows a strong correlation with the hydrational behaviour of the solute molecule and appears to be sensitive to the structural features of the solute, such as shape, size, branching, and presence of aromatic rings. It is argued that these aspects are important in terms of considering the geometrical fit of the solute into the ordered form of the aqueous solvent surrounding these solutes.Key words: apparent molar adiabatic compressibilities, apparent molar volumes, hydration of drugs.MOHAMMAD IQBAL et R. E. VERRALL. Can. J. Chem. 67, 727 (1989). Utilisant des mesures de haute prtcision de la densitt ainsi que de la vitesse du son, a 25"C, on a calculC les volumes et les compressibilitCs molaires apparentes de solutions aqueuses des drogues suivantes: salicylate de mCthyle, orange de mtthyle, L-tryptophane, phCnol ainsi que les chlorhydrates de la propanolamine, de la procaine, du piloc&ne et de 1'CphCdrine. Ces drogues sont souvent considCrtes comme importantes dans plusieurs phenomknes biochimiques tels que la liaison anormale des protkines, I'anesthCsie ou une relation structure-activitC particulikre; cette ttude a Ct C rCalisCe dans le cadre d'un examen gtntral des interactions drogues-protCines dans des systkmes biologiques. Qualitativement, on interprkte ces donnees en fonction d'interactions solute-solvant et solutC-solute. On discute de quelques modes plausibles pour l'hydratation des drogues et en particulier la structure des drogues. I1 existe une importante corrtlation entre les compressibilitCs adiabatiques et les possibilitts d'hydratation des moltcules en solution vis-a-vis de I'hydratation; de plus, elles semblent Stre sensibles aux caractkristiques structurales du solutt, comme la forme, la grosseur, les ramifications et la presence de noyaux aromatiques. On suggkre que ces aspects sont importants lorsqu'on veut insCrer ces solutCs dans la forme ordonnte du solvant aqueux qui entoure ces solutCs.

Partial molar volumes (P) and adiabatic compressibilities (k") of di-, tri-, and tetraglycine have been calculated from high precision density and sound velocity measurements carried out at 25 "C. The contributions (V",o(gly) and K,"(gly)) of the glycyl unit, in a peptide of hypothetical infinite length, are estimated by four different techniques. Final values, obtained by averaging the concordant data, are 37.51 i 0.07 cm3 mol-' and (-8.50 k 0.01) X cm3 mol-' bar-' for V-"(gly) and kmo(gly), respectively. These values are required for use in a revised additivity scheme for calculating partial specific volumes and compressibilities of proteins. Contributions of the peptide group (-CONH-) to P and P are also estimated by comparing with data of o,w-amino acids. The values of i"(-CONH-) and R"(-CONH-) estimated in this way are 20.61 cm3 mol-' and -12.4 X cm3 mol-' bar-', respectively. Some plausible modes of peptide solvation also are discussed.

In order to take into account the Fermi distribution function a t finite T for the number of occupied states in eq 8 and 9, it is useful to divide the integral eq 5 into three parts:The first integral gives the number of occupied states for the temperature equal to 0 K. The second integral represents the occupied states above E F and the third the vacant states below EF. SinceflE -EF) andf(EF -E) decay quickly with increasing values of IE -EFI, one can approximate the second and third integral by developing D(E) in a power series around D(EF).with z = E -EF/(kT) and the minus sign valid for the third integral.Introducing the new parameter z, the difference between the second and third integral AZ is -k T dzOne sees that by inserting the series of eq A2 into eq A3 all terms cancel except those of the second term of the series:The last integral has the value 0.8225'' and replacing dz by dE, one obtains as the final approximationThe integral over all occupied states in an electronic energy band, Z(EF) of eq 5 , can therefore be approximated by Registry No. Graphite, 7782-42-5.Proteinsolvent and protein-protein interactions in aqueous solutions are interpreted from calculated partial specific volumes (&O), adiabatic compressibilities (&O). and expansibilities (&O) obtained from high-precision density and sound velocity measurements at 20,25, 30, 35, and 40 OC. The results provide some information about the structural and dynamic features of these proteins and show a greater dependence of volumetric data on hydrophobicity than on any other protein characteristic. Hemoglobin has a larger content of apolar amino acids in a quaternary structure and this is reflected by larger changes in dVo, &.so, and deo with temperature, relative to the serum albumins which have fewer apolar amino acids and a tertiary structure. Subtle differences between the globular structure of BSA and HSA are revealed from compressibility and expansibility data which not only support some previous observations but also provide new information about the surface polarity and distribution of hydrophobicity within these molecules. A slight but systematic concentration dependence of &, $J~,~, and is observed in this temperature range which is interpreted in terms of protein dynamics. It is argued that, with increasing temperature, microunfolding of the protein molecule increases the probability of exposing some of the buried apolar residues to the solvent, thereby altering the surface hydration. The mechanism of solutesolute interactions thus changes as the hydration shells of interacting protein molecules begin to overlap. IntroductionOne convenient way to study intermolecular interactions is by thermodynamic methods. A number of studies of protein solutions

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Medical students' preference for one teacher over another is directly correlated with a teacher's ability to teach, his or her interpersonal skills, as well as personal and professional qualities.

Dalam proses penetasan telur, suhu merupakan salah satu faktor yang penting untuk dilakukan pengendalian. Pada penelitian ini elemen pemanas dimanfaatkan sebagai heater. Suhu yang stabil akan mempengaruhi dari kualitas dan kuantitas dari tetas telur ayam. Setting Point suhu yang digunakan pada penelitian ini dikisaran 38°C. Metode yang digunakan pada penelitian ini berbasis research and development, dengan memanfaatkan sistem kendali logika fuzzy tipe sugeno orde nol sebagai pengendalinya dan pemrograman java untuk aplikasi software yang digunakan. Dari penelitian dihasilkan sistem kendali suhu dengan respon sistem yang dibutuhkan sistem untuk mencapai kondisi steady state selama 1.084,9 detik tanpa adanya gangguan, sedangkan untuk kondisi sistem dengan adanya gangguan membutuhkan waktu untuk mencapai kondisi steady state selama 126.9 detik.

The major objective of the study was to explore teachers perceptions about the importance of facial expression in the teaching-learning process. All the teachers of government secondary schools constituted the population of the study. A sample of 40 teachers, both male and female, in rural and urban areas of district Peshawar, were selected through a simple random sampling technique. Data were collected through a questionnaire containing ten items regarding facial expressions. It was concluded that teachers deemed the technology of facial expressions very essential and important, not only for themselves, but also for the attainment of students learning outcomes.

Dimasa sekarang ini robot banyak digunakan dalam berbagai bidang kehidupan, terdapat berbagai jenis robot yang dikembangkan salah satunya adalah robot lengan karena memiliki fungsi yang sama dengan lengan manusia. Salah satu kendala dalam pengoperasian robot adalah karena kebanyakan robot memerlukan pemrograman terlebih dahulu untuk mengoperasikan sehingga sulit bagi orang awam. Tujuan dari penelitian ini adalah membuat sistem kendali lengan robot yang dapat mengendalikan lengan robot hanya dengan menggerakan tangan dan menekan tombol. Penelitian ini menggunakan sensor MPU-6050 sebagai sensor sudut dan potensiometer sebagai pengatur gerakan robot, selain itu juga menggunakan Arduino Uno sebagai pengolah masukan sensor agar dapat mengendalikan lengan robot. Adapun robot yang digunakan adalah robot lengan 4 DOF (Degree Of Freedom) dengan penggerak motor servo. Penelitian ini menggunakan metode research and development yaitu dengan mempelajari dan mengembangkan penelitian sebelumnya. Pengujian sensor MPU-6050 mendapatkan hasil dengan nilai error pembacaan sebesar 0,72% pada sumbu X dan 0,68% pada sumbu Y. Waktu yang dibutuhkan untuk sekali proses pemindahan barang adalah selama 3 detik. Hasil dari sistem yang telah dibuat, robot mampu memindahkan barang ketempat yang diinginkan. Tingkat keberhasilan proses pindah barang menggunakan robot lengan 4 DOF adalah 100%.