Herbicides have consistently contributed to yield increases in crop production for many decades however, those same herbicides are facing the loss of effectiveness because of the rapid spread of weed resistance. Since the first instance of herbicide resistance to triazine herbicides over 50 years ago, resistant biotypes have been observed to the major herbicides numbering more than 150 different weed species due to excessive use of single mode of action (MoA)treatments combined with limited crop rotation practices. In the US, the most well-known broad-spectrum herbicide used in major crops, glyphosate is facing huge challenges due to the appearance of many resistant weed species. The consequences of the loss of effectiveness of the current herbicide choices, coinciding with an increasing world population with improved living standards, is beginning to present a severe constraint on food security globally. Unfortunately, the agriculture industry has been unable to find any new mechanism in the last 30 years. The absence of choices of novel active ingredients along with the increased costs of developing new entities is forcing the industry to rely on older modes of action which, with limited application, means lower annual yields of the major crops as the number of resistant weed species increases. The Chemical Genomics group in FMC Agricultural Solutions Discovery has been building ‘Chemistry to Gene’ (C2G) capability to identify new MoAsby applying chemical genomics tools. We have recently discovered that compounds described in WO2017075559A1, are potent selective herbicides with novel action that control many grasses. As a result of knowledge of the mechanism of this area of chemistry, we have extended the work to include a ‘Gene to Chemistry’ (G2C) approach to provide new structural starting points for more synthesis projects.

Type I clathrate was produced by arc melting and hot pressing and thermoelectric properties were investigated. Negative Seebeck coefficient at all temperatures measured, which means that the majority carriers are electrons. Electrical conductivity decreased by increasing temperature and thermal conductivity was 0.012 W/cmK at room temperature and dimensionless thermoelectric figure of merit (ZT) was 0.01 at 873K.

The precipitation behaviors of γ″(Ni3Nb) in four Ni-base alloys were investigated. The four alloys were forged Ni20Cr20Fe5Nb alloy, mechanically alloyed Ni20Cr20Fe5Nb alloy, IN 718 alloy and ECAPed(equal channel angular pressing) IN 718 alloy. Aging treatment was employed at either 600℃ or 720℃ for 20 hrs. The TEM observation and hardness test were performed to identify the formation of γ″. The precipitation of γ″ was noticed after aging at 600℃ for 20 hrs in the mechanically alloyed Ni20Cr20Fe5Nb alloy and ECAPed IN 718 alloy, while it was observed after aging at 720℃ for 20 hrs in the forged Ni20Cr20Fe5Nb alloy and IN 718 alloy before ECAP. The lower aging temperature for γ″ precipitation in the mechanically alloyed Ni20Cr20Fe5Nb alloy and ECAPed IN 718 alloy than in the forged Ni20Cr20Fe5Nb alloy and IN 718 alloy before ECAP appeared to be due to the severe plastic deformation which occurred during mechanical alloying or ECAP.

Fe doped skutterudite CoSb3 with a nominal composition of FexCo1-xSb12 (0≤x≤2.5) have been synthesized by mechanical alloying (MA) of elemental powders, followed by vacuum hot pressing. Phase transformations during mechanical alloying and vacuum hot pressing were systematically investigated using XRD. Single phase skutterudite was successfully produced by vacuum hot pressing using as-milled powders without subsequent annealing. However, second phase of FeSb2 was found to exist in case of x≥2, suggesting the solubility limit of Fe with Co in this system. Thermoelectric properties as functions of temperature and Fe contents were evaluated for the hot pressed specimens. Fe doping up to x=1.5 with Co in FexCo4-xSb12 appeared to increase thermoelectric figure of merit (ZT) and the maximum ZT was found to be 0.78 at 525K in this study.

Ni-doped was prepared by the encapsulated induction melting and hot pressing, and its doping effects on the thermoelectric properties were investigated. Single phase was successfully obtained by the subsequent heat treatment at 773K for 24 hours. Nickel atoms acted as electron donors by substituting cobalt atoms. Thermoelectric properties were remarkably improved by the appropriate doping.

The encapsulated induction melting and hot pressing were employed to prepare Fe-doped skutterudites and their thermoelectric properties were investigated. Single phase was successfully obtained by the subsequent heat treatment at 773K for 24 hours. Iron atoms acted as electron acceptors by substituting cobalt atoms. Thermoelectric properties were remarkably improved by the appropriate doping. was found as an optimum composition for best thermoelectric properties in this work.

Undoped powders were synthesized by mechanical alloying (MA) of elemental powders using a nominal stoichiometric composition. Nano-structured, single-phase skutterudite was successfully produced by vacuum hot pressing (VHP) using MA powders without subsequent annealing. Phase transformations during synthesis were investigated using XRD, and microstructure was observed using SEM and TEM. Thermoelectric properties in terms of Seebeck coefficient, electrical conductivity, thermal conductivity and figure of merit(ZT) were systematically measured and compared with the results of analogous studies. Lattice thermal conductivity was reduced owing to increasing phone scattering in nano-structured MA , leading to enhancement in the thermoelectric figure of merit. MA associated with VHP technique offers an alternative potential processing route for the process of skutterudite.

기계적 합금화 공정을 이용하여 열전재료FeSi2분말을 제조하여 열간압축법을 사용하여 성형하였다. 열간압축 성형된 FeSi2는 열전특성을 나타내는 β-FeSi2 상 및 상변태가 완료되지 않은 α-Fe2Si5와 ε-FeSi의 혼합상으로 이루어져 있음이 확인되었다. 열전재료로의 β-FeSi2 상변태 유도를 위해 항온열처리를 행하여 상변태 조건을 조사하였다. SEM, TEM, XRD, DTA 등을 이용하여 상변태 거동을 분석한 결과, 830˚C에서 24시간 진공 항온열처리 후 단상의 β-FeSi2 상을 얻을 수 있었다. 항온열처리 전의 열간압축 성형체와 상변태가 완료된 β-FeSi2의 기계적 성질과 열전 특성을 측정하여 비교 분석하였다.