The Marcellus tight gas shale represents a significant resource within the northeastern United States. It is both a large reserve, with an estimated 30 to 300 TCF of recoverable gas, and is close to some of the largest prospective markets in the country. However, production is fraught with technological obstacles, the most significant of which include prospecting, access by drilling, stimulation, and recovery. Prospecting is difficult because viability of the reservoir relies both on the original gas in place and in the ability to access that gas through pre-existing fractures that may be developed through stimulation. Drilling is a challenge since drilling costs typically comprise 50% of the cost of the wells and access to the reservoir is improved with horizontal drilling which may access a longer productive zone within the reservoir than cheaper vertical wells. Finally, stimulation methods are necessary to improve gas yields and to reduce the environmental impacts of both consumptive water use and the subsequent problems of safe disposal of fracwater waste. We discuss the challenges involved in the economic recovery of gas from tight gas shales in general and the Marcellus in particular.

The Cambrian succession in the North China Platform comprises a mixed carbonate-siliciclastic sequence, superbly exposed in the southern part of Shandong Province, China. In order to refine the lithostratigraphy of the Cambrian succession, this paper presents detailed sedimentary logs of outcrop sections in the Jinan, Laiwu, Jining, and Linyi areas. The entire succession consists of six lithologic units: Liguan, Zhushadong, Mantou, Zhangxia, Gushan, and Chaomidian formations in ascending order. The upper boundary of the Zhushadong Formation is refined as the base of the first purple mudstone bed of the Mantou Formation. The Mantou Formation is, in turn, bounded at the top by a thick oolitic grainstone bed of the Zhangxia Formation. The upper boundary of the Gushan Formation is placed at the base of a distinct bioclastic grainstone bed of the Chaomidian Formation. The constituent members of the Zhushadong, Mantou, and Chaomidian formations are also refined. Seventeen trilobite biozones are recognized, representing the Cambrian Series 2 to the Furongian.

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Background As the prevalence of antibiotic resistance is increasing, the effectiveness of traditional Helicobacter pylori (H pylori) therapies is gradually declining. We aimed to evaluate the efficacy of tailored therapy (dual priming oligonucleotide [DPO]‐based multiplex PCR) and previous antibiotic exposure survey predicting for antibiotic resistance. Materials and Methods Patients with H pylori infection who did not receive previous treatment were enrolled. The patients were divided into four groups (no resistance [NR] group, clarithromycin resistance [CLA‐R] group, metronidazole‐resistant [MET‐R] group, and CLA‐ and MET‐resistant [Dual‐R] group) based on the results of dual priming oligonucleotide (DPO) polymerase chain reaction (PCR) and previous antibiotic exposure survey, and they were treated with tailored therapy based on antibiotic susceptibility. Results Consecutive patients were distributed in the NR (n = 36, 70.6%), CLA‐R (n = 9, 17.6%), and suspected MET‐R (n = 6, 11.8%) group. The overall intention‐to‐treat/per‐protocol eradication rate (ITT/PP) was 92.2%/94.0%. In the subgroup analysis, the ITT and PP of the NR, CLA‐R, and MET‐R groups were 94.4%/94.4%, 77.8%/87.5%, and 100.0%/100.0%, respectively. Total of 31 patients in all subgroups were evaluated for antibiotic resistance; five (16.1%), two (6.5%), and three (9.7%) participants showed CLA, MET, and dual resistance in culture‐based susceptibility test. Compared with culture‐based MIC test, the accuracy of DPO‐based multiplex PCR in determining CLA resistance was 90.3%, while the accuracy of survey in determining MET resistance was only 77.4%. Conclusion A tailored therapy based on DPO‐PCR and history of previous antibiotic use is useful in clinical practice and well correlated with culture‐based susceptibility test.