Covalent enzyme coupling on cellulose acetate membranes for glucose sensor development

International audienceMethods for immobilizing glucose oxidase (GOx) on cellulose acetate (CA) membranes are compared. The optimal method involves covalent coupling of bovine serum albumin (BSA) to CA membrane and a subsequent reaction of the membrane with GOx, which has previously been activated with an excess of p-benzoquinone. This coupling procedure is fairly reproducible and allows the preparation of thin membranes (5-20 µm) showing high surface activities (1-3 U/cm2) which are stable over a period of 1-3 months. Electrochemical and radiolabeling experiments show that enzyme inactivation as a result of immobilization is negligible. A good correlation between surface activity of membranes and their GOx load is observed

Risk-based prioritization of pharmaceuticals in the natural environment in Iraq

Numerous studies have demonstrated the occurrence of pharmaceuticals in the natural environment, raising concerns about their impact on non-target organisms or human health. One region where little is known about the exposure and effects of pharmaceuticals in the environment is Iraq. Due to the high number of pharmaceuticals used by the public health sector in Iraq (hospitals and care centres) and distributed over the counter, there is a need for a systematic approach for identifying substances that should be monitored in the environment in Iraq and assessed in terms of environmental risk. In this study, a risk-based prioritization approach was applied to 99 of the most dispensed pharmaceuticals in three Iraqi cities, Baghdad, Mosul and Basrah. Initially, information on the amounts of pharmaceuticals used in Iraq was obtained. The top used medicines were found to be paracetamol, amoxicillin and metformin with total annual consumption exceeding 1000 tonnes per year. Predicted environmental concentrations (PECs) and predicted no-effect concentrations (PNECs), derived from ecotoxicological end-points and effects related to the therapeutic mode of action, were then used to rank the pharmaceuticals in terms of risks to different environmental compartments. Active pharmaceutical ingredients used as antibiotics, antidepressants and analgesics were identified as the highest priority in surface water, sediment and the terrestrial environment. Antibiotics were also prioritized according to their susceptibility to kill or inhibit the growth of bacteria or to accelerate the evolution and dissemination of antibiotic-resistant genes in water. Future work will focus on understanding the occurrence, fate and effects of some of highly prioritized substances in the environment

Interdependence between transportation system and power distribution system: a comprehensive review on models and applications

The rapidly increasing penetration of electric vehicles in modern metropolises has been witnessed during the past decade, inspired by financial subsidies as well as public awareness of climate change and environment protection. Integrating charging facilities, especially high-power chargers in fast charging stations, into power distribution systems remarkably alters the traditional load flow pattern, and thus imposes great challenges on the operation of distribution network in which controllable resources are rare. On the other hand, provided with appropriate incentives, the energy storage capability of electric vehicle offers a unique opportunity to facilitate the integration of distributed wind and solar power generation into power distribution system. The above trends call for thorough investigation and research on the interdependence between transportation system and power distribution system. This paper conducts a comprehensive survey on this line of research. The basic models of transportation system and power distribution system are introduced, especially the user equilibrium model, which describes the vehicular flow on each road segment and is not familiar to the readers in power system community. The modelling of interdependence across the two systems is highlighted. Taking into account such interdependence, applications ranging from long-term planning to short-term operation are reviewed with emphasis on comparing the description of traffic-power interdependence. Finally, an outlook of prospective directions and key technologies in future research is summarized.fi=vertaisarvioitu|en=peerReviewed

HUBUNGAN KUAT TEKAN BETON ANTARA HASIL UJI TEKAN KUBUS DAN UJI TEKAN SILINDER PADA BETON DENGAN AGREGAT PULAU TIMOR

Benda uji silinder atau kubus diperlukan untuk menentukan kuat tekan beton. Benda uji kubus berdimensi 15cmx15cmx15cm sedangkan bentuk silinder berdimensi 15cmx30cm. Ketersediaan cetakan benda uji silinder di lapangan sering tidak terpenuhi karena persediaan yang terbatas dan memaksa seorang tenaga supervisi mengijinkan menggunakan cetakan benda uji kubus untuk menguji mutu beton yang sedang dikerjakan.  Sesuai PBI 1971 untuk melakukan konversi kuat tekan beton berdasarkan benda uji kubus   sehingga setara dengan kuat tekan beton dengan benda uji silinder dikalikan faktor 0.83 atau menggunakan formula f’c=(0,76+ 0,2log(f’ck/15)).f’ck (Nugraha, et al, 2007 dan Mulyono, 2003). Agregat alam berupa pasir dan krikil di Pulau Timor alam merupakan batuan endapan bukan merupakan material hasil erupsi gunung api sehingga karakteristiknya berbeda. Kajian dilakukan untuk mengevaluasi faktor konversi 0,83 dan formula f’c=(0,76+0,2log(f’ck/15)).f’ckpada beton dengan  agregat Pulau Timor.  Penelitian dilakukan dengan benda uji beton dengan agregat Quarry Takari di Pulau Timor, berjumlah 30 buah terdiri dari 15 buah berbentuk silinder dan 15 buah berbentuk kubus. Masing-masing mutu beton disiapkan 3 benda uji yaitu untuk mutu K-175, K-200, K-225, K-250 dan K-300. Setelah benda uji dirwat selama 28 hari di laboratorium kemudian dilakukan uji kuat tekan.Hasil ratio rata-rata hubungan kuat tekan benda uji kubus dan silinder beton dengan agregat Pulau Timor sebesar 0.83 dan dalam fungsi regresi linear dengan persamaan f’c = 0,822 f’ck + 0,312, dimana f’c dan f’ck dalam MPa dengan nilai slump 30-60 mm dengan Koefisien korelasi (r) = 0.905 dan koefisien determinasi (r2) = 0.819, menunjukkan 81,90% nilai kuat tekan beton f’c dapat ditentukan berdasarkan hasil pengujian benda uji kubus dan 18,10% ditentukan faktor lain. Rata-rata faktor konversi hasil penelitian sebesar 0,83 sama dengan yang dicantumkan dalam PBI 1971 dan formula konversi hasil penelitian : f’c = 0,822f’ck+0,312 menunjukkan rerata perbedaan absolut sebesar 0,82 MPa atau 3,17%  dengan formula f’c=(0,76+0,2log(f’ck/15)).f’ck