Electrical conduction by interface states in semiconductor heterojunctions

peer reviewedaudience: researcher, professionalElectrical conduction in semiconductor heterojunctions containing defect states in the interface region is studied. As the classical drift-diffusion mechanism cannot in any case explain electrical conduction in semiconductor heterojunctions, tunnelling involving interface states is often considered as a possible conduction path. A theoretical treatment is made where defect states in the interface region with a continuous energy distribution are included. Electrical conduction through this defect band then allows the transit of electrons from the conduction band of one semiconductor to the valence band of the second component. The analysis is initiated by electrical measurements on n-CdS/p-CdTe heterojunctions obtained by chemical vapour deposition of CdS on (111) oriented CdTe single crystals, for which current--voltage and capacitance--frequency results are shown. The theoretical analysis is based on the numerical resolution of Poisson's equation and the continuity equations of electrons, holes and defect states, where a current component corresponding to the defect band conduction is explicitly included. Comparison with the experimental curves shows that this formalism yields an efficient tool to model the conduction process through the interface region. It also allows us to determine critical values of the physical parameters when a particular step in the conduction mechanism becomes dominant

Novel, synergistic antifungal combinations that target translation fidelity

There is an unmet need for new antifungal or fungicide treatments, as resistance to existing treatments grows. Combination treatments help to combat resistance. Here we develop a novel, effective target for combination antifungal therapy. Different aminoglycoside antibiotics combined with different sulphate-transport inhibitors produced strong, synergistic growth-inhibition of several fungi. Combinations decreased the respective MICs by ≥8 fold. Synergy was suppressed in yeast mutants resistant to effects of sulphate-mimetics (like chromate or molybdate) on sulphate transport. By different mechanisms, aminoglycosides and inhibition of sulphate transport cause errors in mRNA translation. The mistranslation rate was stimulated up to 10-fold when the agents were used in combination, consistent with this being the mode of synergistic action. A range of undesirable fungi were susceptible to synergistic inhibition by the combinations, including the human pathogens Candida albicans, C. glabrata and Cryptococcus neoformans, the food spoilage organism Zygosaccharomyces bailii and the phytopathogens Rhizoctonia solani and Zymoseptoria tritici. There was some specificity as certain fungi were unaffected. There was no synergy against bacterial or mammalian cells. The results indicate that translation fidelity is a promising new target for combinatorial treatment of undesirable fungi, the combinations requiring substantially decreased doses of active components compared to each agent alone

Heterologous expression of a novel drug transporter from the malaria parasite alters resistance to quinoline antimalarials

Antimalarial drug resistance hampers effective malaria treatment. Critical SNPs in a particular, putative amino acid transporter were recently linked to chloroquine (CQ) resistance in malaria parasites. Here, we show that this conserved protein (PF3D7_0629500 in Plasmodium falciparum; AAT1 in P. chabaudi) is a structural homologue of the yeast amino acid transporter Tat2p, which is known to mediate quinine uptake and toxicity. Heterologous expression of PF3D7_0629500 in yeast produced CQ hypersensitivity, coincident with increased CQ uptake. PF3D7_0629500-expressing cultures were also sensitized to related antimalarials; amodiaquine, mefloquine and particularly quinine. Drug sensitivity was reversed by introducing a SNP linked to CQ resistance in the parasite. Like Tat2p, PF3D7_0629500-dependent quinine hypersensitivity was suppressible with tryptophan, consistent with a common transport mechanism. A four-fold increase in quinine uptake by PF3D7_0629500 expressing cells was abolished by the resistance SNP. The parasite protein localised primarily to the yeast plasma membrane. Its expression varied between cells and this heterogeneity was used to show that high-expressing cell subpopulations were the most drug sensitive. The results reveal that the PF3D7_0629500 protein can determine the level of sensitivity to several major quinine-related antimalarials through an amino acid-inhibitable drug transport function. The potential clinical relevance is discussed

Scholarly publishing depends on peer reviewers

The peer-review crisis is posing a risk to the scholarly peer-reviewed journal system. Journals have to ask many potential peer reviewers to obtain a minimum acceptable number of peers accepting reviewing a manuscript. Several solutions have been suggested to overcome this shortage. From reimbursing for the job, to eliminating pre- publication reviews, one cannot predict which is more dangerous for the future of scholarly publishing. And, why not acknowledging their contribution to the final version of the article published? PubMed created two categories of contributors: authors [AU] and collaborators [IR]. Why not a third category for the peer-reviewer

Scholarly publishing depends on peer reviewers

The peer-review crisis is posing a risk to the scholarly peer-reviewed journal system. Journals have to ask many potential peer reviewers to obtain a minimum acceptable number of peers accepting reviewing a manuscript. Several solutions have been suggested to overcome this shortage. From reimbursing for the job, to eliminating pre-publication reviews, one cannot predict which is more dangerous for the future of scholarly publishing. And, why not acknowledging their contribution to the final version of the article published? PubMed created two categories of contributors: authors [AU] and collaborators [IR]. Why not a third category for the peer-reviewer?Scopu

Pengaruh Penerapan Metode Drill And TutorialTerhadap Peningkatan Hasil dan Motivasi Belajar Mahasiswa Program Studi Pendidikan Fisika Universitas Muhammadiyah Mataram

Penelitian ini tentang pengaruh penerapan metode Drill and Tutorial terhadap peningkatan hasil dan motivasi belajar mahasiswa program studi pendidikan fisika Universitas Muhammadiyah Mataram Tahun Akademik 2013/2014. Penelitian ini dilaksanakan dengan tujuan (1) mengetahui pengaruh penerapan metode Drill and Tutorial terhadap hasil belajar mahasiswa; (2) mengetahui pengaruh penerapan metode Drill and Tutorial terhadap motivasi belajar mahasiswa; (3) membandingkan tingkat pemahaman konsep mahasiswa menggunakan pembelajaran metode Drill and Tutorial dengan metode konvensional. Jenis penelitian ini adalah penelitian eksperimen. Populasi dalam penelitian ini adalah semua mahasiswa semester V Program Studi pendidikan Fisika Universitas Muhammadiyah Mataram Tahun Akademik 2013/2014. Sampel penelitiandiambil dengan teknik purposive sampling yang terbagi menjadi 2 kelas sampel. Kelas VA ditentukan sebagaikelas eksperimen dan kelas VB sebagai kelas kontrol. Jumlah sampel pada penelitian ini adalah 31 mahasiswa antara lain 16 mahasiswa kelas eksperimen dan 17 mahasiswa kelas kontrol. Data tentang hasil belajar mahasiswadikumpulkan dengan metode tes menggunakan tes hasil belajar, dianalisis dengan menentukan skor rata-rata dan ketuntasan klasikal, sedangkan data tentang motivasi belajar mahasiswa terhadap metode pembelajaran yang diterapkan dikumpulkan dengan teknik angket dan dianalisis dengan menentukan kategori skor rata-rata. Berdasarkan hasil analisis data statistik dapat disimpulkanbahwa (1) penerapan pembelajaran dengan metode Tutorial and Drill memiliki pengaruh yang signifikan terhadap hasil belajar mahasiswa pada mata kuliah fisika modern, yaitu nilai rata-rata mahasiswa sebesar 69,69 pada kelas eksperimen, sedangkan nilai rata-rata mahasiswa sebesar 57,06 pada kelas kontrol. (2) penerapan pembelajaran dengan metode Tutorial and Drill memiliki pengaruh yang signifikan terhadap motivasi belajar mahasiswa pada mata kuliah fisika modern, yaitu sebelum diberikan perlakuan jumlah mahasiswa yang memiliki motivasi baik sebesar 25%, sedangkan setelah diberikan perlakuan jumlah mahasiswa yang memiliki motivasi baik (positif) meningkat menjadi 81,25%. (3) terdapat perbedaan yang signifikan antara pembelajaran menggunakan metode Drill and Tutorial dibandingkan dengan pembelajaran metode konvensional terhadap peningkatan hasil belajar mahasiswa pada mata kuliah fisika moder

Sensor Getaran Dua Dimensi (2-d) Berbasis Koil Datar untuk Mengukur Frekuensi Getaran Gempa di Wilayah Lombok Nusa Tenggara Barat

Pada penelitian ini telah dirancang aplikasi koil datar sebagai sensor getaran untuk deteksi dini gempa. Koil datar adalah lilitan kawat yang sangat tipis dan bertindak sebagai induktor. Koil datar ini bersama dengan kapasitor membangun sebuah osilator yang menghasilkan frekuensi bergantung pada nilai induktansi dan kapasitansi. Osilator ini dinamakan osilator LC. Induktansi koil datar bergantung pada jarak benda logam di depan koil datar. Jika induktansi berubah, frekuensi akan berubah juga. Frekuensi dapat dirubah ke dalam bentuk tegangan untuk merepresentasikan jarak. Efek ini kemudian diterapkan pada frekuensi rendah menggunakan bandul pada rumahan sensor. Berdasarkanpenelitian, sensor getaran untuk mendeteksi gempa bumi sudah dirancang serta masih dalam proses pengujian dan kalibrasi. Sensor getaran yang sudah dibuat adalah sensor koil datar arah x da arah y. Frekuensi getaran yang sudah bisa diukur dalam arah x adalah 0,468 Hz. Nilai ini hampir sama dengan frekuensi sumber getaran sebesar 0,46 Hz. Adapun frekuensi yang getaran yang sudah bisa diukur dalam arah y adalah 0,55 Hz dan nilai ini hampir sama dengan frekuensi sumber getaran sebesar 0,5 Hz

Affordability of essential medicine prices in Malaysia’s private health sector

Nur Sufiza Ahmad,1 Farida Islahudin2 1Pharmaceutical Services Division, Ministry of Health Malaysia, Petaling Jaya, Malaysia; 2Faculty of Pharmacy, Universiti Kebangsaan Malaysia, Kuala Lumpur, Malaysia Background: The lack of price control in Malaysia has led to increased market competition, resulting in high medicine prices, notably in the private sector. This largely affects patients’ out-of-pocket expenses in the private sector. Although generic medicines are preferred due to affordability, the prices are still notably high.Methods: This study compares innovator and generic medicine prices to estimate treatment affordability in the private sector. Private hospitals and community retail pharmacies were examined from 2011 to 2015. Data were collected on the basis of recommendations by the World Health Organization’s Health Action International.Results: The markup of generic medicines was significantly higher than that of innovator medicines during the study period (p<0.001). While the markup of generic medicine was 31%–402% (36%–171% and 31%–402% for core and supplementary list items), that of innovator medicine was 24%–86% (28%–86% and 24%–80% for core and supplementary list items). There was no significant increase in the median price ratio for 11 selected generic medicines (from 1.8±3.9 to 2.9±8.2) (p>0.05). However, the median price ratio of the 11 innovator medicines significantly increased (from 4.9±6.1 to 11.2±20.3) (p=0.045). Affordability of all generic medicines was below the 2-day wage for treatment, with captopril (25 mg tablet) reporting the highest cost (1.1–1.7-day wages). Among innovator medicines, omeprazole (20 mg capsule; 6.2–7.0 days’ wages) reported the highest median treatment cost.Conclusion: There is a need for policies to control national drug prices, to ensure medicine prices are monitored. This can help keep out-of-pocket expenses, especially in middle-income countries such as Malaysia, at a minimal in the private sector. Keywords: community medicine, patient education, pharmacy, hospital&nbsp

Medication adherence in patients with type 2 diabetes mellitus treated at primary health clinics in Malaysia

Nur Sufiza Ahmad,1 Azuana Ramli,1 Farida Islahudin,2 Thomas Paraidathathu21Pharmaceutical Services Division, Ministry of Health, Petaling Jaya, Malaysia; 2Faculty of Pharmacy, Universiti Kebangsaan Malaysia, Kuala Lumpur, MalaysiaPurpose: Diabetes mellitus is a growing global health problem that affects patients of all ages. Even though diabetes mellitus is recognized as a major chronic illness, adherence to antidiabetic medicines has often been found to be unsatisfactory. This study was conducted to assess adherence to medications and to identify factors that are associated with nonadherence in type 2 diabetes mellitus (T2DM) patients at Primary Health Clinics of the Ministry of Health in Malaysia.Materials and methods: The cross-sectional survey was carried out among T2DM patients to assess adherence to medication in primary health clinics. Adherence was measured by using the Medication Compliance Questionnaire that consists of a total of seven questions. Other data, such as patient demographics, treatment, outcome, and comorbidities were also collected from patient medical records.Results: A total of 557 patients were recruited in the study. Approximately 53% of patients in the study population were nonadherent. Logistic regression analysis was performed to predict the factors associated with nonadherence. Variables associated with nonadherence were age, odds ratio 0.967 (95% confidence interval [CI]: 0.948–0.986); medication knowledge, odds ratio 0.965 (95% CI: 0.946–0.984); and comorbidities, odds ratio 1.781 (95% CI: 1.064–2.981).Conclusion: Adherence to medication in T2DM patients in the primary health clinics was found to be poor. This is a cause of concern, because nonadherence could lead to a worsening of disease. Improving medication knowledge by paying particular attention to different age groups and patients with comorbidities could help improve adherence.Keywords: type 2 diabetes mellitus, adherence, glycemic control, primary car