Autoxidation of Hydrocarbons: From Chemistry to Catalysis

This contribution summarizes our recent efforts to unravel the radical chemistry of autoxidations. Abstraction of the weakly bonded αH-atom of the primary hydroperoxide product by chain carrying peroxyl radicals is identified as the source of major end products such as alcohol and ketone/aldehyde. In the case of cyclohexane autoxidation, this reaction is even responsible for the majority of ring-opened by-products. In a second part, different approaches to autoxidation catalysis are discussed, ranging from transition metal ion catalysis to organocatalysis with immobilized N-hydroxyphthalimid

Autoxidation Chemistry: Bridging the Gap Between Homogeneous Radical Chemistry and (Heterogeneous) Catalysis

During the autoxidation of cyclohexane, abstraction of the αH-atom of the hydroperoxide product by chain-carrying peroxyl radicals produces both the desired alcohol and ketone products, as well as the majority of by-products. Rationalizing the impact of this reaction, one should aim for a (catalytic) destruction of this hydroperoxide without the intervention of peroxyl chain-carriers. Starting from these new insights in the molecular mechanism, attempts for rational catalyst design are initiate

Strategi Pengembangan Agroindustri Keripik Pisang (Studi Kasus pada Seorang Pengusaha Keripik Pisang di Desa Hegarmanah Kecamatan Cidolog Kabupaten Ciamis)

Penelitian ini bertujuan untuk mengetahui besarnya biaya, penerimaan dan pendapatan, faktor internal dan eksternal yang berpengaruh terhadap pengembangan agroindustri keripik pisang, alternatif strategi yang dapat diterapkan dalam pengembangan agroindustri keripik pisang di Desa Hegarmanah Kecamatan Cidolog Kabupaten Ciamis. Jenis penelitian yang digunakan dalam penelitian ini adalah metode studi kasus. Data yangdikumpulkan meliputi data primer dan data sekunder. Penarikan responden dalam penelitian ini dilakukan purposive sampling yaitu penetuan sampel dengan pertimbangan tertentu yang dipandang dapat memberikan data secara maksimal, maka responden yang diambil satu orang pengusaha keripik pisang dan sebagai responden pendukung yaitu satu orang Pemerintah Desa Hegarmanah dan satu orang dari Dinas Pertanian.Hasil penelitian menunjukan bahwa:1) Besarnya biaya total yang dikeluarkan oleh pengusaha keripik pisang dalam satu kali proses produksi sebesar Rp 1.369.385,67, penerimaannya sebesar Rp 2.500.000,00 dan pendapatannya sebesar Rp 1.130.614,33.2) Faktor internal dan eksternal yang berpengaruh pada pengembangan agroindustri keripik pisang di Desa Hegarmanah Kecamatan Cidolog Kabupaten Ciamis terdiri dari kekuatan, kelemahan dan peluang, ancaman. Faktor-faktor yang menjadi kekuatan yaitu tersedianya cukup jumlah tenaga kerja, produksi mudah dilakukan, produk keripik pisang yang tahan lama, harga produkyang terjangkau. Sedangkan faktor-faktor yang menjadi kelemahan yaitu keterbatasan permodalan, kualitas SDM yang masih kurang, pengemasan produk masih sederhana, dan promosi masih kurang. Faktor-faktor yang menjadi peluang yaitu tidak ada pesaing produk sejenis disatu daerah, pangsa pasar yang masih luas, permintaan semakin meningkat, cuaca tidak mempengaruhi produksi. Faktor-faktor yang menjadi ancaman yaitu kelangkaan bahanbaku, fluktuasi harga bahan baku, kurang adanya peran dari pemerintah, dan kenaikan harga sarana produksi.3) Alternatif strategi yang dapat diterapkan dalam pengembangan agroindustri keripik pisang di Desa Hegarmanah Kecamatan Cidolog Kabupaten Ciamis yaitu mempertahankan kualitas produksi dan pengembangan pasar, mempertahankan kontinyuitas produksi untuk memenuhi permintaan, optimalisasi kualitas SDM untuk memenuhi permintaan produk, diversifikasi produk untuk memenuhi pangsa pasar, pengelolaan tenaga kerja dan ketersediaan bahan baku,keseragaman harga jual dengan peran serta pengawasan pemerintah, penganekaragaman pengemasan untuk memaksimalkan produksi dan menjalin kerja sama dengan pihak terkait dalam menyikapi permodalan

ESR evidence for disordered magnetic phase from ultra-small carbon nanotubes embedded in zeolite nanochannels

A multi-frequency electron spin resonance (ESR) study provides evidence for the occurrence of low temperature ferromagnetic/spin-glass behavior in aligned arrays of sub-nanometer single walled carbon nanotubes confined in zeolite nano-channels, owing to sp2-type non-bonding carbon associated localized states with density of ~3 x 1019 /g. Features related to the much anticipated conduction ESR are not detected. In the paramagnetic phase, the ESR linewidth is found to be weakly dependent on microwave frequency.Comment: Accepted to be published in EuroPhysics Letter

Shape-selective zeolite catalysis for bioplastics production

Biodegradable and renewable polymers, such as polylactic acid, are benign alternatives for petrochemical-based plastics. Current production of polylactic acid via its key building block lactide, the cyclic dimer of lactic acid, is inefficient in terms of energy, time, and feedstock use. We present a direct zeolite-based catalytic process, which converts lactic acid into lactide. The shape-selective properties of zeolites are essential to attain record lactide yields, outperforming those of the current multistep process by avoiding both racemization and side-product formation. The highly productive process is strengthened by facile recovery and practical reactivation of the catalyst, which remains structurally fit during at least six consecutive reactions, and by the ease of solvent and side-product recycling

Diagnostic performance of a novel loop-mediated isothermal amplification (LAMP) assay targeting the apicoplast genome for malaria diagnosis in a field setting in sub-Saharan Africa.

BACKGROUND: New diagnostic tools to detect reliably and rapidly asymptomatic and low-density malaria infections are needed as their treatment could interrupt transmission. Isothermal amplification techniques are being explored for field diagnosis of malaria. In this study, a novel molecular tool (loop-mediated isothermal amplification-LAMP) targeting the apicoplast genome of Plasmodium falciparum was evaluated for the detection of asymptomatic malaria-infected individuals in a rural setting in The Gambia. METHODS: A blood was collected from 341 subjects (median age 9 years, range 1-68 years) screened for malaria. On site, a rapid diagnostic test (RDT, SD Bioline Malaria Antigen P.f) was performed, thick blood films (TBF) slides for microscopy were prepared and dry blood spots (DBS) were collected on Whatman(®) 903 Specimen collection paper. The TBF and DBS were transported to the field laboratory where microscopy and LAMP testing were performed. The latter was done on DNA extracted from the DBS using a crude (methanol/heating) extraction method. A laboratory-based PCR amplification was done on all the samples using DNA extracted with the Qiagen kit and its results were taken as reference for all the other tests. RESULTS: Plasmodium falciparum malaria prevalence was 37 % (127/341) as detected by LAMP, 30 % (104/341) by microscopy and 37 % (126/341) by RDT. Compared to the reference PCR method, sensitivity was 92 % for LAMP, 78 % for microscopy, and 76 % for RDT; specificity was 97 % for LAMP, 99 % for microscopy, and 88 % for RDT. Area under the receiver operating characteristic (ROC) curve in comparison with the reference standard was 0.94 for LAMP, 0.88 for microscopy and 0.81 for RDT. Turn-around time for the entire LAMP assay was approximately 3 h and 30 min for an average of 27 ± 9.5 samples collected per day, compared to a minimum of 10 samples an hour per operator by RDT and over 8 h by microscopy. CONCLUSION: The LAMP assay could produce reliable results the same day of the screening. It could detect a higher proportion of low density malaria infections than the other methods tested and may be used for large campaigns of systematic screening and treatment

Decadal ocean forcing and Antarctic ice sheet response: Lessons from the Amundsen Sea

Mass loss from the Antarctic Ice Sheet is driven by changes at the marine margins. In the Amundsen Sea, thinning of the ice shelves has allowed the outlet glaciers to accelerate and thin, resulting in inland migration of their grounding lines. The ultimate driver is often assumed to be ocean warming, but the recent record of ocean temperature is dominated by decadal variability rather than a trend. The distribution of water masses on the Amundsen Sea continental shelf is particularly sensitive to atmospheric forcing, while the regional atmospheric circulation is highly variable, at least in part because of the impact of tropical variability. Changes in atmospheric circulation force changes in ice shelf melting, which drive step-wise movement of the grounding line between localized high points on the bed. When the grounding line is located on a high point, outlet glacier flow is sensitive to atmosphere-ocean variability, but once retreat or advance to the next high point has been triggered, ocean circulation and melt rate changes associated with the evolution in geometry of the sub-ice-shelf cavity dominate, and the sensitivity to atmospheric forcing is greatly reduced