Modelling and solving an <Emphasis Type="Italic">m</Emphasis>-location, <Emphasis Type="Italic">n</Emphasis>-courier,priority-based planning problem on a network

In this paper, we study an m-location, n-courier, priority-based planning problem on a network, which we refer to as the Courier Planning Problem (CPP). The CPP arises on a daily basis in the context of planning the transportation of materials and personnel in peacetime for the Turkish Armed Forces. The main issue addressed in CPP is to transport as many of deliverables as possible from their origins to their destinations via a fleet of transportation assets (couriers) that operate at fixed routes and schedules. Priorities must be taken into account and constraints on the routes, operating schedules, and capacities of the transportation assets must be obeyed. Time windows may be specified for some or all transportation requests and must be satisfied. We study the CPP as well as its two extensions, and present integer programming formulations based on the multi-commodity flow structure. The formulations are tested on real world-based data and display satisfactory computational performance. Our main contributions are to develop an effective formulation scheme for a complicated large-scale real world problem and to demonstrate that such problems are solvable via commercial general purpose solvers through meticulous modelling.     

Outstanding effect of the conformational restriction of isoquinolines: hints for the development of optimized antimicrobial agents

Conformational restriction constitutes a useful strategy of molecular modification for the design of new potential drug candidates. Herein we present the planning, antimicrobial evaluation, and establishment of structure–activity relationship (SAR) data for some isoxazole (3a–k, 8a–c, and 9a–c) and pyrazole (5a–h) derivatives. These derivatives were structurally designed by conformational restriction followed by bioisosteric exchange of previously described antimicrobial isoquinolines (1a–c). Some of these more conformationally restricted derivatives present improved properties as new antibacterial drug candidates.     

Phage Displayed HBV Core Antigen with Immunogenic Activity

Hepatitis B is a major public health problem worldwide, which may lead to chronic liver diseases such as cirrhosis and hepatocellular carcinoma. The hepatitis B core antigen (HBcAg) is one of the major viral proteins, which forms the inner core of hepatitis B virus (HBV) particles. In this study, filamentous bacteriophage M13 was genetically modified to display the polypeptides of HBcAg in order to develop an alternative carrier system. HBcAg gene was inserted into the minor coat protein (pIII) gene of M13, and HBcAg was expressed on the phage surface as a whole protein. Antigenicity and immunogenicity of HBcAg were tested by immunizing BALB/c mice three times with HBcAg-displaying recombinant phages. After successful immunization, one of the mice with high antibody titer to HBcAg was selected for fusion, and four monoclonal antibodies specific for HBcAg were developed. This result showed that HBcAg-displaying recombinant bacteriophages are immunogenic and can potentially be used for the development of monoclonal antibodies.     

A simple and sensitive LC-ESI-MS (ion trap) method for the determination of bupropion and its major metabolite, hydroxybupropion in rat plasma and brain microdialysates

A specific and highly sensitive liquid chromatography-electrospray mass spectrometry (LC-ESI-MS) method for the direct determination of bupropion (BUP) and its main metabolite hydroxybupropion (HBUP) in rat plasma and brain microdialysate has been developed and validated. The analysis was performed on a Bonus RP C18 (100 mm × 2.1 mm i.d., 3.5 μm particles) column using gradient elution with the mobile phase consisting of acetonitrile and ammonium formate buffer (10 mM, pH 4). Plasma samples were analyzed after a simple, one-step protein precipitation clean-up with trichloroacetic acid (TCA), however clean-up for microdialysis samples was not necessary, enabling direct injection of the samples into the LC-ESI-MS system. Signals of the compounds were monitored under the multiple reaction monitoring (MRM) mode of the LC-ESI-MS (ion trap) for quantification. The precursor to product ion transitions of m/z 240-184 and m/z 256-238 were used to measure BUP and HBUP, respectively. The method was validated in both plasma and microdialysate samples, and the obtained lower limit of quantification (LLOQ) was 1.5 ng mL⁻¹ for BUP and HBUP in both matrices. The intra- and inter-day assay variability was less than 15% for both analytes. This LC-ESI-MS method provided simple sampling, rapid clean-up and short analysis time (<9 min), applicable to the routine therapeutic monitoring and pharmacokinetic studies of BUP and HBUP.     

New insights on the single machine total tardiness problem

Virtually all algorithmic studies on the single machine total tardiness problem use Emmons’ theorems that establish precedence relations between job pairs. In this paper, we investigate these theorems with a geometric viewpoint. This approach provides a compact way of representing Emmons’ theorems and promotes better insights into dominance properties. We use these insights to differentiate between certain classes of easy and hard instances.     

Entropy generation in a square enclosure with partial heating from a vertical lateral wall

The entropy generation during the transient laminar natural convection in a square enclosure that is partially heated from a vertical lateral wall is numerically investigated. The active sites referring to the main irreversibility locations are determined. The Boussinesq approximation is used in the natural convection modelling. The effects of Prandtl (Pr) and Rayleigh (Ra) number combinations on the entropy generation are investigated. The study is restricted to the fluids of Prandtl number from 0.01 to 1.0, and Rayleigh numbers in the range of 10²–10⁸. It is found that the upper corner of the heated part of the side wall is the active site where the entropy generation initiates due to irreversibilities representing the energy loss.     

HPLC Separation of Different Groups of Small Polar Compounds on a Novel Amide-Embedded Stationary Phase

Retention behaviors of an amide-embedded silica base stationary phase, which was recently developed by our group, were studied by using six different groups of small polar compounds including phenolic compounds, substituted anilines, chlorinated herbicides, Sudan dyes and some nucleotides and nucleosides in HPLC. The chromatographic behaviors of the prepared stationary phase for these analytes were compared with those of a commercially available reversed-phase column ACE C18 under same conditions. Among the six groups of analytes studied, the amide-silica stationary phase showed enhanced selectivity towards phenolic compounds, substituted anilines, Sudan dyes and herbicides under reversed-phase conditions and satisfactory selectivity towards nucleosides and nucleotides which could not be separated with ACE C18 column under HILIC conditions. Experimental data provided some evidence that functional groups on the stationary phases might have certain degrees of influence on selectivity possibly through secondary interactions with the model compounds. The retentions of the moderately polar compounds such as phenolic acids, anilines and herbicides on the stationary phase are higher than highly polar compounds such as nucleotides and nucleosides due to both the hydrophobic and hydrophilic interactions between the stationary phase and analytes. The quantitative determination of Sudan dyes (I, II, III, and IV) in red chilli peppers was performed. Many red chilli peppers were screened and three of them contained Sudans dyes.

     

Using dynamic software in mathematics: the case of reflection symmetry

This study was carried out to examine the effects of computer-assisted instruction (CAI) using dynamic software on the achievement of students in mathematics in the topic of reflection symmetry. The study also aimed to ascertain the pre-service mathematics teachers’ opinions on the use of CAI in mathematics lessons. In the study, a mixed research method was used. The study group of this research consists of 30 pre-service mathematics teachers. The data collection tools used include a reflection knowledge test, a survey and observations. Based on the analysis of the data obtained from the study, the use of CAI had a positive effect on achievement in the topic of reflection symmetry of the pre-service mathematics teachers. The pre-service mathematics teachers were found to largely consider that a mathematics education which is carried out utilizing CAI will be more beneficial in terms of ‘visualization’, ‘saving of time’ and ‘increasing interest/attention in the lesson’. In addition, it was found that the vast majority of them considered using computers in their teaching on the condition that the learning environment in which they would be operating has the appropriate technological equipment.     

Fiber optic sodium and potassium sensing by using a newly synthesized squaraine dye in PVC matrix

In recent years squarines received attention as fluorescent labels. Their very promising spectral properties such as long wavelength absorption and emission, high extinction coefficients and quantum yields could lead novel sensing technologies. In this work newly synthesized fluoroinophores named bis[4-N-(1-aza-4,7,10,13-tetraoxacyclopentadecyl)-3,5-dihydroxyphenyl]squaraine, azacrown-1 and 2 bis[4-N-(1-aza-4,7,10,13,16-pentaoxacyclooctadecyl)-3,5-dihydroxyphenyl]squaraine, azacrown-2 have been used for sodium and potassium sensing in plasticized PVC matrix. The squaraine derivatives exhibited fluorescence emission based optical responses to sodium and potassium with a detection limit of 1.10(-9) M. The sensor compositions exhibited wide response ranges between 10(-9) and 10(-5) M Na(+)or K(+), and, therefore, may be an alternative method to flame emission spectroscopy. The sensor is fully reversible within the dynamic range and the response time is 3 min under batch conditions. Cross sensitivity to pH is negligible in the pH range of 6.2-7.3. Throughout fiber optic based studies a relative signal change of 54-56% has been achieved. The azacrown dyes have the advantage that they can be excited with long wavelength light and, are, therefore, LED compatible. The cross sensitivity of azacrown-1 and -2 to Ba(2+), Ca(2+) and NH(4)(+)were also tested in separate solutions.     

Emission based oxygen sensing approach with tris(2,2′-bipyridyl)ruthenium(II)chloride in green chemistry reagents: room temperature ionic liquids

Room temperature ionic liquids doped with tris(2,2′-bipyridyl)ruthenium(II)chloride together with chemically and biochemically inert perfluoro chemicals (PFCs) have been used for the first time for optical O₂ sensing purposes. The response to oxygen of the Ru complex in 1-methyl-3-butylimidazolium tetrafluoroborate (RTIL-I) and 1-methyl-3-butylimidazolium bromide (RTIL-II) has been evaluated in terms of sensitivity, stability, regeneration ability and response time. The response times were 2 and 5 s, respectively, and the signal changes were reversible. Better oxygen solubility, enhanced molar absorption coefficients and photostabilies were found for the RTILs. The stability the Ru complex in RTILs was tested over 12 months and it is when stored in the ambient air of the laboratory. Correspondence: Kadriye Ertekin, Fen-Edebiyat Fakultesi, Dokuz Eylul Universitesi, Kimya Bolumu, 35160 Buca, Izmir, Turkey