Chemical Studies on the Stability of Soil Aggregates : Change in Permeability of Soil Aggregate Column Induced bu Percolating with Neutral and Alkaline Solution

既報の結果に基づいて推論した粒団生成に関与する成分が, 果して土粒子の耐水性連結にいかなる役割を演じているかを明らかにする研究の一環として, 静置状態で土壌粒団に中性ならびにアルカリ性の溶液を透過させて土壌から特定の成分の離脱を試み, その場合に起こる粒団の崩壊と土壌の持つ透液性の変移をしらべた。1. 主として水溶性と置換性の成分を土壌から溶脱する機能のある0.05N塩化ナトリウム溶液を土壌粒団に透過させると土壌粒団の崩壊ならびに透液性の低下は極めて少なかった。したがって, 置換性塩基類は粒団の安定性に対し大きな役割を果していないことが明らかになった。2. アルカリ性の腐植抽出剤である0.5%水酸化ナトリウム溶液を土壌粒団に透過させると, 粒団の崩壊が著しく, それに応じて土壌の持つ透液性も低下した。しかし, 土壌からの腐植の離脱量と透液性の低下との間に認められた相関は高くないので粒団の安定性は腐植の単独作用によって律せられるものでないことがわかった。この際同時にアルミニウムがかなり多量に離脱され, これが粒団の安定性に関与することが類推された。3. 中性の腐植抽出剤である0.1Mピロ燐酸ナトリウム溶液を土壌粒団に透過させると, 土壌の種類によってその程度はかなり異なるが概して粒団崩壊と透液比の低下は大きかった。ところが, 土壌から離脱した腐植量と透液比の低下との間には相関が見出せなかった。ピロ燐酸ナトリウム溶液は土壌から腐植と同時に鉄, アルミニウム, カルシウムなどの無機成分を溶脱し, これらの正電荷を抑えて土粒の分散を促がす機能が高いから, この場合の粒団の崩壊はとくに同時に離脱する鉄やアルミニウムによるところが大きいと考えられる。 / With the object to determine the kinds of binding materials in soil aggregates and the part played by each of them, experiments were made on the effect of percolation with neutral or alkaline solution on the aggregate stability. The results obtained are as follows : 1) Aggregates were not greatly affected by the treatment with 0.05N sodium chloride solution. Hence, the part played by exchangeable bases appeared not large in the stabilization of aggregates. 2) When 0.5% sodium hydroxide solution was passed through the column to remove humus from aggregates, the permeability was remarkably lowered. But since the amount of humus removed was not so closely related to the degree of lowering in permeability, the aggregate stability did not seem attributable to the function of humus alone. It was suggested that aluminum removed from aggregates in a large amount in addition to humus participates in their stability. 3) When treated with 0.1M sodium pyrophosphate solution, neutral reagent for humus extraction, the aggregates were markedly broken down and their permeability was greatly lowered, though not without some differences in the extent of effect among the kinds of soil. On the other hand, no distinct correlation was found between the amount of humus removed and the degree of lowering in permeability ratio (the ratio of the permeability at any given time after treatment, Pt, to the initial permeability, Pi). In this case, inorganic components such as aluminum and iron, which were removed by sodium pyrophosphate solution in addition to humus, were considered to be intimately concerned with the result. 4) From these results, it may be indicated that the part played by the combined action of humus and aluminum or iron is important for the stability of soil aggregates

Apert syndrome: the Paris and Rotterdam philosophy

Introduction: Apert syndrome is a rare type of syndromic craniosynostosis. Patients have an explicit phenotype with craniofacial dysmorphologies and severe symmetrical syndactyly of the hands and feet. This review includes background information about the syndrome and several aspects of the treatment. Areas covered: The cause of Apert syndrome is found in unique mutations in the Fibroblast Growth Factors Receptor (FGFR) 2 gene in 99%. It results in cranial suture fusion, craniofacial dysmorphologies and severe symmetrical syndactyly of the hands and feet. Patients with Apert syndrome are at risk for mental retardation, mobility impairment and intracranial hypertension (ICHT). This is the result of a complex interaction between (1) abnormal skull growth, (2) ventriculomegaly, (3) venous outflow obstruction and (4) obstructive sleep apnea (OSA). Mental retardation is mainly determined by the FGFR2 mutation and treatment is directed at protecting the intrinsic potential of neurocognition. Expert Opinion: To prevent ICHT, we prefer an occipital expansion in the first year of life. Screening on ICHT and its underlying causes is necessary at least until the age of ten by means of skull circumference measurements, fundoscopy, optical coherence tomography, MRI and polysomnography. Multicentre studies on long-term outcome are required to validate the rationale of different clinical protocols