Biomedical subjects

H-D Park

Publications and source records attributed to H-D Park.

2 recordsLinked to original sources

PubMed2003

Personal-computer-based three-dimensional reconstruction and simulation of maxillary sinus.

Anatomical descriptions of the maxillary sinus are critical in pathological diagnosis and the treatment planning of surgical procedures. This study was undertaken to develop a new technique for simulating anatomical structures and to clarify the morphological and clinical characteristics of the maxillary sinus. Thirty-three hemi-sectioned Korean heads were used in this study. CT scans and DentaScan reformatted cross-sectional images were taken on all specimens. From the CT images, three-dimensional reconstructed images were made using the V-works program. From the three-dimensional reconstructed images of the maxillary sinus, six categories of maxillary sinus were created, categorized according to their lateral aspects and shapes of the inferior walls. In 55%, a flat inferior wall of the maxillary sinus was observed. All measurements (anterior-posterior length, height, width and volume) of the sinus were larger in males than in females. From the DentaScan reformatted panoramic images, the anterior limit of the maxillary sinus was located in the first premolar area (58%), and the posterior limit was in the third molar and maxillary tuberosity area (94%). We therefore offer a new virtual technique for manipulating three-dimensional reconstructed images easily on a personal computer. On the reconstructed images the three-dimensional morphology could be observed and the anatomical characteristics of the maxillary sinus and surrounding structures could be determined.

Anatomy, Cross-Sectional↗

PubMed2002

Molecular analysis of ammonia-oxidizing bacterial populations in aerated-anoxic orbal processes.

Aerated-anoxic processes operate under the principle that small additions of oxygen to an anoxic reactor induce simultaneous nitrification and denitrification. In these systems, ammonia oxidation in the anoxic zone can easily account for 30-50% of the total nitrification in the reactor, even though the dissolve oxygen concentration is usually below detection limit. To investigate whether the nitrification efficiency in aerated-anoxic processes was due to the presence of specialized ammonia-oxidizing bacteria (AOB), an analysis of the AOB population in an aerated-anoxic Orbal process and a conventional nitrogen removal process was carried out using phylogenetic analyses based on the ammonia monooxygenase A (amoA) gene. Terminal restriction fragment length polymorphism (TRFLP) analyses revealed that Nitrosospira-like organisms were one of the major contributors to ammonia oxidation in a full-scale aerated-anoxic Orbal reactor. However, the relative populations of Nitrosospira-like and Nitrosomonas-like AOB were not constant and appeared to have seasonal variability. Cloning and sequence comparison of amoA gene fragments demonstrated that most of the AOB in the aerated-anoxic Orbal process belonged to the Nitrosospira sp. and Nitrosomonas oligotropha lineages. The abundance of Nitrosospira-like organisms in aerated-anoxic reactors is significant, since this group of AOB has not been usually associated with nitrification in wastewater treatment plants.

Ammonia↗