An updated age for the Xujiayao hominin from the Nihewan Basin, North China: Implications for Middle Pleistocene human evolution in East Asia.

The Xujiayao site in the Nihewan Basin (North China) is one of the most important Paleolithic sites in East Asia. Twenty Homo fossils, which were previously assigned to an archaic Homo sapiens group, have been excavated along with more than 30,000 lithic artifacts and ∼5000 mammalian fossil specimens. Dating of the Xujiayao hominin has been pursued since its excavation in the 1970s, but its age has remained controversial because of limitations of the dating techniques that have been applied to available materials. Here, we report new ages for the Xujiayao hominin based on combined electron spin resonance (ESR) dating of quartz in the sediments and high-resolution magnetostratigraphy of the fluvio-lacustrine sequence. The magnetostratigraphy suggests that the upper Matuyama and Brunhes polarity chrons are recorded at Xujiayao. The ESR dating results indicate a pooled average age of 260-370 ka for the Homo-bearing layer, which is consistent with its position within the middle Brunhes normal polarity chron indicated by magnetostratigraphy. This age estimate makes the Xujiayao hominin among the oldest mid-Pleistocene hominins with derived Neanderthal traits in East Asia. This age is consistent with the time when early Denisovans, a sister group of Neanderthals, appeared and colonized eastern Eurasia. Our updated age and the Neanderthal-like traits of the Xujiayao Homo fossils, particularly the Denisovan-like molar teeth, make it possible that the Xujiayao hominin could represent an early Denisovan.

ESR dating of the Majuangou and Banshan Paleolithic sites in the Nihewan Basin, North China.

The fluvio-lacustrine sequences in the Nihewan Basin, northern China provide an important source of Paleolithic settlements and therefore early human occupation in the eastern Old World. Here we present electron spin resonance (ESR) chronology for the Majuangou (MJG-III, MJG-II and MJG-I) and Banshan (BS) Paleolithic sites in this basin by the quartz Ti-Li center ESR dating. Results show that the ages of MJG-III and MJG-II could be estimated to be ∼1.70 Ma (millions of years ago); of MJG-I, ∼1.40 Ma; and BS, ∼1.35 Ma. This ESR chronology is consistent with the previous magnetochronology, thus providing strong support for the earliest human presence at the high northern latitudes of Northeast Asia.

Monitoring and control of UV and UV-TiO2 disinfections for municipal wastewater reclamation using artificial neural networks.

The use of ultraviolet (UV) irradiation as a physical wastewater disinfection has increased in recent years, especially for wastewater reuse. The UV-TiO(2) can generate OH radicals, which is highly effective to inactivate microorganisms in wastewater disinfection. However, both UV and UV-TiO(2) disinfections create multiple physical, chemical, and bio-chemical phenomena that affect their germicidal efficiency. It is difficult to build a precise control model using existing mathematic models. This study applies artificial neural network (ANN) models to control UV and UV-TiO(2) disinfections. Experimental results indicate that the ANN models, which precisely generate relationships among multiple monitored parameters, total coliform counts in influent and effluent, and UV doses, can be used as control models for UV and UV-TiO(2) disinfections. A novel ANN control strategy is applied to control UV and UV-TiO(2) disinfection processes to meet three total coliform count limits for three wastewater reuse purposes. The proposed controlled strategy effectively controls UV and UV-TiO(2) disinfection, resulting in acceptable total coliform counts in effluent for the three wastewater reuse purposes. The required UV doses for UV-TiO(2) disinfection were lower than those for UV disinfection, resulting in energy saving and capacity reduction of 13.2-15.7%.