ALBERT

Notes: Effects of implanted hydrogen on removal of oxygen from a Si top layer on buried oxide by the post-implantation annealing were studied. The Si top layer and the buried oxide layer were analyzed by secondary ion mass spectroscopy (SIMS) and cross-sectional transmission electron microscopy (X-TEM). With implanted hydrogen, oxygen concentration in the Si top layer could be reduced below the SIMS detection limit by annealing at relatively lower temperature 1150 °C for 2 h in an ambient of N2. It is verified by X-TEM that the Si top layer is precipitate-free. An amount of hydrogen comparable to the amount of oxygen contained in the Si top layer is needed to remove the oxygen completely. This effective removal of oxygen is attributed to the suppression of oxygen precipitation and the enhanced dissolution of oxide precipitates by hydrogen.

Notes: Summary. The phytotoxicity of numerous herbicides was measured on cucumber, sorghum, and wheat plants in terms of the minimum lethal concentration of herbicide in nutrient solution surrounding the roots of photosynthetizing plants. Wheat and cucumber were about equally sensitive as test plants, while, sorghum at a similar growth stage required ten to one hundred times the concentration (on a molar basis) of most chemicals for lethal effect. Only paraquat as a root-absorbed herbicide appeared to be completely non-selective to all three species. The triazines showed considerable selectivity to sorghum; of all the triazines tested only CP-17029 was more toxic to wheat and sorghum than to cucumber.None of the compounds were ethal at a concentration of 10−7 molar (7.00, expressed as the negative logarithm); the triazine G-34360 (desmetryne) showed the greatest toxicity (6.85) to the cucumber plant. Diuron on the same species had a toxicity rating of 6.69 and bromacil 6.72.Mesure de la phytotoxicité des herbicides au moyen de l'absorption radiculaire

Notes: Summary. 1. Laboratory methods of evaluating herbicides were developed to determine their relative effectiveness as inhibitors of seed-germination, seedling growth and juvenile plants under photosynthetic conditions.2. Chemicals such as dinoseb, PGP and diquat were found to be very toxic to seeds, all of them having an MDso lower than 4 × 10−5 for both radish (Raphanus sativus L.) and Sudan grass (Sorghum sudanense Stapf).3. Of the chemicals examined, the most toxic to radish seed were dinoseb, PCP, octochlorocyclohexenone, tetrachlorophenol, 2,4-dinitrophenol, hexachloro-2,5-cyclo-hexadiene-1-one and pentabromophenol in that order. Nitrophenols were more toxic to the seeds than the corresponding chloro-derivatives but pentachloronitrobenzene was inactive.4. 2,6-Dichlorobenzonitrile and chlorpropham (CIPC) were found to be especially toxic to Sudan grass seed.5. 2,4,5-T, 2,6-dichlorobenzonitrile and diquat were extremely toxic to germinating cucumber (Cucumis sativus L.) seeds, while the latter two and chlorpropham were very toxic to Sudan grass seedlings. Other herbicides which were quite phytotoxic to plants in this stage are 2,4-D, 2-methoxy-3,6-dichlorobenzoic acid (cucumber), dinoseb, PGP, EPTC and 2,3,6-TBA (Sudan grass).6. Diuron, atrazine, monuron and simazine were found to be quite inactive on the seeds and seedlings tested but extremely phytotoxic to young cucumber plants grown in. the light. Molar concentrations from 10−7 to 10−8, applied only to the roots, were found to be lethal under the conditions employed. Ametryne, prometryne, 2,4,5-T, JV-(3,4-dichlorophenyl)-N'-methoxy-JV'-methylurea and EPTC were also lethal at this dosage while fenac, 2,4-D and fenuron were lethal from 10−6 to 10−5 M.7. In all the tests, 2,4,5-T was found to be quite effective being especially toxic to germinating cucumber seeds.Evaluation au laboratoire de quelques herbicides〈section xml:id="abs1-1"〉〈title type="main"〉Résumé1. Des méthodes d'évaluation des herbicides au laboratoire ont été créées pour déterminer leur activité comme inhibiteurs de la germination et de la croissance des plantules et des jeunes plantes dans les conditions de la photosynthèse.2. Des produits tels que le dinoseb, le PCP et le diquat ont été reconnus comme très toxiques pour les semences. Ils présentent tous une DLso inférieure à 4 × 10−5 pour le radis (Raphanus sativus L.) et le Sudan grass (Sorghum sudanense Stapf).3. De tous les produits examinés, les plus actifs furent, dans l'ordre, le dinoseb, le PCP, l'orthochlorocyclo-hexanone, le tetrachlorophenol, le 2,4-dinitrophénol, l'hexachloro2,5-cyclohexadiène-l-one et le pentabromophenol. Les nitrophénols furent plus toxiques pour les semences que les dérivés chlorés correspondants, mais le pentechloronitrobenzène fut inactif.4. Le 2,6-dichlorobenzonitrile et le chlorpropham (CIPC) se révélèrent particulièrement toxiques pour les semences de Sudan grass.5. Le 2,4,5-T, le 2,6-dichlorobenzonitrile et le diquat furent extrémement toxiques pour les graines en germination de concombre (Cucumis sativus L.) cependant que les deux derniers et le chlorpropham furent très toxiques pour les semences de Sudan grass. Les autres herbicides qui furent extrémement toxiques pour les plantes à ce stade furent le 2,4-D, l'acide 2-méthoxy-3,6-dichlorobenzoïque (concombre) le dinoseb, le PCP, I'EPTC et le 2,3,6-TBA (Sudan grass).6. Le diuron, l'atrazine, le monuron et la simazine se montrèrent totalement inactifs sur les semences et les plantules mais tres phytotoxiques pour les jeunes plantes de concombre poussant a Ia lumiere. Des concentrations molaires de 10−7 a 10−6 appliquées seulement aux racines se montrèrent létales dans les conditions où elles furent employées. L'amétryne, la prometryne, le 2,4,5-T, la N-(3,4-dichlorophényle)-N'-méthoxy-N'-méthy-Iurée et I'EPTC produisirent le même effet pour la meme dose, tandis que le fénac le 2,4-D et le fénuron furent létaux de 10−á 10–5 M.7. Dans tous les tests, le 2,4,5-T a été trouvé très actif et spécialement toxique pour les graines de concombre en germination.