Influence of ultrafiltration membrane characteristics on adsorptive fouling with dextrans

This paper presents a detailed investigation of fouling mechanisms for ultrafiltration membranes with polysaccharides obtained by studying membrane–solute (static adsorption) and membrane–solute–solute interactions (ultrafiltration (UF)). Two polyethersulfone (PES) membranes and one stabilized cellulose (cellulosic) membrane with a nominal cut-off of 10 kg/mol and dextrans with average molar mass (M) of 4, 10 and 15 kg/mol were used. The membranes before and after static adsorption of dextran were characterized by captive bubble contact angle and tangential streaming potential measurements as well as ultrafiltration sieving curves for polyethylene glycols. Significant water flux reductions (4–15%), which also correlated with dextran molar mass, and changes of the other membrane characteristics occurred after static dextran adsorption for the PES membranes. An empirical model to describe the correlation between the relative water flux reduction and the concentration of solute had also been proposed. In contrast, no significant changes could be detected for the cellulosic membrane. Significant membrane–solute interactions had also been confirmed in the ultrafiltration experiments with dextrans where irreversible fouling had been observed for the PES but not for the cellulosic membranes. The results provide fundamental information for a better understanding of fouling by polysaccharides. In particular, it had been confirmed that hydrophilic and neutral dextrans can significantly foul PES membranes via adsorption to the surface of the membrane polymer. On this basis, methods for control of this fouling can be properly developed

Solitons in a parametrically driven damped discrete nonlinear Schr\"odinger equation

We consider a parametrically driven damped discrete nonlinear Schr\"odinger (PDDNLS) equation. Analytical and numerical calculations are performed to determine the existence and stability of fundamental discrete bright solitons. We show that there are two types of onsite discrete soliton, namely onsite type I and II. We also show that there are four types of intersite discrete soliton, called intersite type I, II, III, and IV, where the last two types are essentially the same, due to symmetry. Onsite and intersite type I solitons, which can be unstable in the case of no dissipation, are found to be stabilized by the damping, whereas the other types are always unstable. Our further analysis demonstrates that saddle-node and pitchfork (symmetry-breaking) bifurcations can occur. More interestingly, the onsite type I, intersite type I, and intersite type III-IV admit Hopf bifurcations from which emerge periodic solitons (limit cycles). The continuation of the limit cycles as well as the stability of the periodic solitons are computed through the numerical continuation software Matcont. We observe subcritical Hopf bifurcations along the existence curve of the onsite type I and intersite type III-IV. Along the existence curve of the intersite type I we observe both supercritical and subcritical Hopf bifurcations.Comment: to appear in "Spontaneous Symmetry Breaking, Self-Trapping, and Josephson Oscillations in Nonlinear Systems", B.A. Malomed, ed. (Springer, Berlin, 2012

Pesantren and the Preservation of Islam Nusantara

This article describes the background of the rise of an Indonesian moderate Islamic understanding in the midst of a trans-national Islamic movement with the scriptural-puritanical in it's character which spread out pervasively in the country; and this new Islamic model is intolerant to local traditions. Meanwhile, historically, Islam Nusantara has been deeply rooted among the Moslems in archipelago, and this traditional-moderate Islam has been developed by Wali-songo. Islam Nusantara is accommodative to the local cultures and traditions. It produces a moderate and tolerant model of Islam. This article also describes the role of pesantren in protecting the heritages of Islam Nusantara. Copyright (c) 2015 by KARSA. All right reservedDOI: 10.19105/karsa.v23i2.71

Business Cycles in International Historical Perspective

This paper examines business cycles theoretically and empirically, with a quantitative study based on experience over the long run and in a cross section of countries. Several major questions in business cycle theory are explored. Theoretical concerns indicate that the properties of business cycle models depend not only on important structural aspects of the model such as money neutrality, labor market structure, and price adjustment, but also on the closure of the model in international markets. Econometric considerations suggest that more information about the country-specific versus universal features of cycles could be gleaned from the study of panel data. A review of business cycle properties in a sample of over a dozen countries is considered in light of these issues.

Partisipasi Masyarakat dalam Pengelolaan Usaha Ekowisata Taman Nasional Tesso Nilo Kabupaten Pelalawan Provinsi Riau (Studi Kasus di Desa Lubuk Kembang Bungo)

This research purposed to get know how the communities participation and how the management of ecotourism in tesso nilo national park lubuk kembang bunga village district ukui sub-district plalawan on the stage of development of ecotourism there and potential to be developed in the Tesso Nilo national park.This study used a qualitative method with descriptive approach to describe the actual state by collecting data and information in the field. The subject of the study researchers used a key informant as many as 16 people are concerned with sub-indicators. While data collection techniques in this study using observation, interviews, and documentation.Based on the research that has been done, the public response to community participation in the management of ecotourism businesses that occurred in the area of Tesso Nilo National Park is already underway in three participation that direct participation, indirect participation, and no participation, each of which has involved the participation of society in every, but the direct participation has not maximize the role of local communities or local in them.Key words : Community participation, ecotourism, Tesso Nilo National Park

Are male orangutans a threat to infants? Evidence of mother-offspring counter strategies to infanticide in Bornean orangutans (Pongo pygmaeus wurmbii)

Sexually selected infanticide by males is widespread in primates. Female primates employ a variety of strategies to reduce infanticide risk. While infanticide has never been directly observed in wild orangutans (Pongo spp.), their slow life history makes infants vulnerable to infanticide. The mating strategies of female orangutans include polyandrous and postconceptive mating that may serve to increase paternity confusion, an infanticide avoidance strategy. Here, we investigate whether female orangutans alter their social interactions with males as another infanticide avoidance strategy. We hypothesize that females with younger offspring avoid males and that the distance between mother and offspring decreases in the presence of males. We use long-term behavioral data collected between 1994 and 2016 from Bornean orangutans (Pongo pygmaeus wurmbii) in Gunung Palung National Park, Indonesia, to test whether the sexual selection hypothesis for infanticide helps explain aspects of orangutan social behavior. We found that mothers with offspring 6 yr. old and females without offspring. In addition, the distance between a mother–offspring dyad showed a statistically significant decrease in the presence of males, but not females. Our results are consistent with the hypothesis that female orangutans employ strategies to reduce infanticide risk in their social interactions. Because orangutans have a high fission–fusion dynamic, they have flexibility in manipulating social interactions as a counter-infanticide strategy. Our results suggest that infanticide by males is a selective pressure shaping female orangutan social behavior.Accepted manuscrip