An update on the compound challenge: 90-44-8

SDS of cas: 90-44-8. About Anthrone, If you have any questions, you can contact Djellout, H; Raio, A; Boutoumi, H; Krimi, Z or concate me.

An article Bacillus and Pseudomonas spp. strains induce a response in phenolic profile and enhance biosynthesis of antioxidant enzymes in Agrobacterium tumefaciens infected tomato plants WOS:000532107100002 published article about INDUCED SYSTEMIC RESISTANCE; CROWN-GALL; PEROXIDASE-ACTIVITY; BIOLOGICAL-CONTROL; SALICYLIC-ACID; BACTERIA; RHIZOBACTERIA; RHIZOSPHERE; GROWTH; BIOCONTROL in [Djellout, H.; Krimi, Z.] Univ Saad Dahlab, Lab Valorisat Ressources Agrobiol, Dept Biotechnol, Fac Sci Nat & Vie, Blidal 09000, Algeria; [Raio, A.] Ist Protez Sostenibile Piante CNR, Via Madonna Piano 10, I-50019 Sesto Fiorentino, FI, Italy; [Boutoumi, H.] Univ Saad Dahlab, Dept Chim Ind, Lab Genie Chim, Blidal, Algeria in 2020, Cited 38. The Name is Anthrone. Through research, I have a further understanding and discovery of 90-44-8. SDS of cas: 90-44-8

Some antagonistic bacteria contribute to the management of plant diseases by stimulating the host natural defense and/or by providing direct biocontrol of pathogens. The objective of this study was to evaluate the biocontrol performances and the ability to induce a systemic response to crown gall of four strains belonging to Bacillus and Pseudomonas genera. Evaluation of in vitro antagonistic ability showed that the four bacteria had a different spectrum of activity against the three tested strains of Agrobacterium tumefaciens. A delay in time of appearance and a significant reduction of the tumor size were observed in tomato plants obtained by bio-primed seeds and stem inoculated with A. tumefaciens. Seed priming with antagonistic strains stimulated some systemic defense mechanisms in tomato plants that can be related to the reduction of disease symptoms induced by A. tumefaciens. Both antagonists and A. tumefaciens strains induced variations in phenol content and peroxidase activity while polyphenol oxidase activity was mainly affected by the single A. tumefaciens strain. The response was different in relation to the various combinations of antagonist/pathogen, however Pseudomonas brassicacearum EPR3 strain was the most effective strain.

SDS of cas: 90-44-8. About Anthrone, If you have any questions, you can contact Djellout, H; Raio, A; Boutoumi, H; Krimi, Z or concate me.

Reference:
Thiomorpholine – Wikipedia,
,Thiomorpholine | C4H9NS – PubChem

 

Discover the magic of the Benzophenone

About Benzophenone, If you have any questions, you can contact Hu, YY; Shao, Y; Zhang, SW; Yuan, Y; Sun, Z; Yuan, Y; Jia, XD or concate me.. Quality Control of Benzophenone

Quality Control of Benzophenone. Authors Hu, YY; Shao, Y; Zhang, SW; Yuan, Y; Sun, Z; Yuan, Y; Jia, XD in PERGAMON-ELSEVIER SCIENCE LTD published article about in [Hu, Yingying; Zhang, Shuwei; Yuan, Yuan; Sun, Zheng; Yuan, Yu; Jia, Xiaodong] Yangzhou Univ, Sch Chem & Chem Engn, Yangzhou 225002, Jiangsu, Peoples R China; [Shao, Yu] Yangzhou Univ, Sch Informat Engn, Huayang West Rd 196, Yangzhou 225127, Jiangsu, Peoples R China in 2021, Cited 43. The Name is Benzophenone. Through research, I have a further understanding and discovery of 119-61-9

A sp(3) C-H bond functionalization and C – C bond cleavage were realized by AIBN/0 2 catalyst system, providing a series of benzophenones under mild reaction conditions. The mechanistic study shows that a peroxide intermediate is involved in this transformation, and in the case of diphenylmethanes, the sp(3) C-C bond is cleaved through the peroxide rearrangement, which might provides a new way to cleave relatively strong C-C bond and be applied to more general C-C bond activation. (C) 2021 Elsevier Ltd. All rights reserved.

About Benzophenone, If you have any questions, you can contact Hu, YY; Shao, Y; Zhang, SW; Yuan, Y; Sun, Z; Yuan, Y; Jia, XD or concate me.. Quality Control of Benzophenone

Reference:
Thiomorpholine – Wikipedia,
,Thiomorpholine | C4H9NS – PubChem

 

Chemistry Milestones Of Benzophenone

Quality Control of Benzophenone. About Benzophenone, If you have any questions, you can contact Pollard, VA; Kennedy, AR; McLellan, R; Ross, D; Tuttle, T; Mulvey, RE or concate me.

Quality Control of Benzophenone. In 2021.0 EUR J INORG CHEM published article about CATALYZED HYDROBORATION; CATECHOLBORANE; REACTIVITY; REDUCTION; MOLECULES; DIFFUSION; CLEAVAGE; HYDRIDE; NMR in [Pollard, Victoria A.; Kennedy, Alan R.; McLellan, Ross; Ross, Duncan; Tuttle, Tell; Mulvey, Robert E.] Univ Strathclyde, Dept Pure & Appl Chem, WestCHEM, Glasgow G1 1XL, Lanark, Scotland in 2021.0, Cited 55.0. The Name is Benzophenone. Through research, I have a further understanding and discovery of 119-61-9.

Dialkylaluminium amides iBu(2)Al(TMP) and iBu(2)Al(HMDS) can perform catalytic hydroboration of ketones with pinacolborane to form the expected boronic esters. However, repeating the same reactions stoichiometrically without a ketone leads unexpectedly to ring-opening of pinacolborane and insertion of its open chain into the Al-N(amido) bond. To date there has been limited knowledge on decomposition pathways of HBpin despite its prominent role in hydroboration chemistry. X-ray crystallography shows these mixed Al-B products [iBu(2)Al{OC(Me)(2)C(Me)(2)O}B(H)(NR2)](2) (NR2=TMP or HMDS) form dimers with an (AlO)(2) core and terminal B-N bonds. Since the bond retention (B-H) and bond breaking (B-O) in these transformations seemed surprising, DFT calculations run using M11/6-31G(d,p) gave an energy profile consistent with a sigma-bond metathesis mechanism where London dispersion interactions between iBu and (amide) Me groups play an important stabilising role in the final outcome.

Quality Control of Benzophenone. About Benzophenone, If you have any questions, you can contact Pollard, VA; Kennedy, AR; McLellan, R; Ross, D; Tuttle, T; Mulvey, RE or concate me.

Reference:
Thiomorpholine – Wikipedia,
,Thiomorpholine | C4H9NS – PubChem

 

An update on the compound challenge: 104-21-2

HPLC of Formula: C10H12O3. About 4-Methoxybenzyl acetate, If you have any questions, you can contact Roser, C; Toth, C; Renner, M; Herpel, E; Schirmacher, P or concate me.

Authors Roser, C; Toth, C; Renner, M; Herpel, E; Schirmacher, P in BMC published article about in [Roser, Christoph; Toth, Csaba; Renner, Marcus; Herpel, Esther; Schirmacher, Peter] Heidelberg Univ Hosp, Inst Pathol, Neuenheimer Feld 224, D-69120 Heidelberg, Germany; [Roser, Christoph] Heidelberg Univ Hosp, Dept Orthodont & Dentofacial Orthopaed, Neuenheimer Feld 400, D-69120 Heidelberg, Germany; [Herpel, Esther] Natl Ctr Tumor Dis NCT, Tissue Bank, Neuenheimer Feld 224, D-69120 Heidelberg, Germany; [Toth, Csaba] Trier MVZ Histol Cytol & Mol Diagnost, Max Planck Str 5, D-54296 Trier, Germany in 2021, Cited 53. HPLC of Formula: C10H12O3. The Name is 4-Methoxybenzyl acetate. Through research, I have a further understanding and discovery of 104-21-2

Background: Colorectal familial adenomatous polyposis (FAP) adenomas exhibit a uniform pathogenetic basis caused by a germline mutation in the adenomatous polyposis gene (APC), but the molecular changes leading to their development are incompletely understood. However, dysregulated apoptosis is known to substantially affect the development of colonic adenomas. One of the key regulatory proteins involved in apoptosis is apoptosis repressor with caspase recruitment domain (ARC). Methods: The expression of nuclear and cytoplasmic ARC in 212 adenomas from 80 patients was analyzed by immunohistochemistry. We also compared expression levels of ARC with the expression levels of p53, Bcl-2, COX-2, and MMR proteins. Statistical analyses were performed by Spearman’s rank correlation and linear regression test. Results: ARC was overexpressed in the nuclei and cytoplasm of most FAP adenomas investigated. Cytoplasmic ARC staining was moderately stronger (score 2) in 49.1% (n = 104/212) and substantially stronger (score 3) in 32.5% (n = 69/212) of adenomas compared to non-tumorous colorectal mucosa. In 18.4% (n = 39/212) of adenomas, cytoplasmic ARC staining was equivalent to that in non-tumorous mucosa. Nuclear expression of ARC in over 75% of cells was present in 30.7% (n = 65/212) of investigated adenomas, and nuclear expression in 10-75% of cells was detected in 62.7% (n = 133/212). ARC expression in under 10% of nuclei was found in 6.6% (n = 14/212) of adenomas. The correlation between nuclear ARC expression and cytoplasmic ARC expression was highly significant (p = 0.001). Moreover, nuclear ARC expression correlated positively with overexpression of Bcl-2, COX-2 p53 and beta-catenin. Cytoplasmic ARC also correlated with overexpression of Bcl-2. Sporadic MMR deficiency was detected in very few FAP adenomas and showed no correlation with nuclear or cytoplasmic ARC. Conclusions: Our results demonstrated that both cytoplasmic and nuclear ARC are overexpressed in FAP adenomas, thus in a homogenous collective. The highly significant correlation between nuclear ARC and nuclear beta-catenin suggested that ARC might be regulated by beta-catenin in FAP adenomas. Because of its further correlations with p53, Bcl-2, and COX-2, nuclear ARC might play a substantial role not only in carcinomas but also in precursor lesions.

HPLC of Formula: C10H12O3. About 4-Methoxybenzyl acetate, If you have any questions, you can contact Roser, C; Toth, C; Renner, M; Herpel, E; Schirmacher, P or concate me.

Reference:
Thiomorpholine – Wikipedia,
,Thiomorpholine | C4H9NS – PubChem

 

More research is needed about 4-Methoxybenzyl acetate

About 4-Methoxybenzyl acetate, If you have any questions, you can contact Horiuchi, S; Ozaki, A; Inoue, M; Aida, J; Yamaoka, K or concate me.. Recommanded Product: 4-Methoxybenzyl acetate

I found the field of General & Internal Medicine; Research & Experimental Medicine very interesting. Saw the article Relation of High Social Capital to Preferable Emotional Response to News Media Broadcasting of Natural Disasters: A Nationwide Cross-Sectional Study in Japan published in 2019. Recommanded Product: 4-Methoxybenzyl acetate, Reprint Addresses Horiuchi, S (corresponding author), Teikyo Univ, Grad Sch Publ Hlth, Itabashi Ku, 2-11-1 Kaga, Tokyo 1738605, Japan.. The CAS is 104-21-2. Through research, I have a further understanding and discovery of 4-Methoxybenzyl acetate

Media coverage of disasters potentially damages mental health. Moreover, its effects may differ as recipients may have different emotional responses toward media. The present study examined whether social capital, known to be protective against mental problems, influences a recipient’s emotional response toward news media broadcasting of natural disasters via newspapers, television and internet in Japan. Three social capital components, social participation, social support and cognitive social capital, were considered in the present study as each component reportedly had different effect on mental health. This nationwide cross-sectional survey was undertaken in 2015 among 1,200 Japanese citizens aged 15 to 79 years who were selected using the multi-stage sampling procedure. Data were collected via the drop-off pick-up method using a printed structured questionnaire. Negative and positive emotions were classified based on recipients’ responses against news media. Among 1,190 participants who reported emotions toward news media, 30.9% (368) had experienced any natural disasters, 37.4% (445) belonged to at least one formal or informal organization (social participation), 40.2% (478) had high social support, and 68.8% (819) had high cognitive social capital. High social support was associated with both reduced negative emotional response (OR 0.66, 95% Confidence Interval (CI) 0.47-0.93) and increased positive emotional response (OR 1.48, 95% CI 1.04-2.12) in multivariate analyses, while high cognitive social capital was only associated with increased positive emotional response (OR 1.62, 95% CI 1.11-2.37). These results suggest protective effects of social support and cognitive social capital against news media coverage of natural disasters.

About 4-Methoxybenzyl acetate, If you have any questions, you can contact Horiuchi, S; Ozaki, A; Inoue, M; Aida, J; Yamaoka, K or concate me.. Recommanded Product: 4-Methoxybenzyl acetate

Reference:
Thiomorpholine – Wikipedia,
,Thiomorpholine | C4H9NS – PubChem

 

Some scientific research about Anthrone

About Anthrone, If you have any questions, you can contact Luo, YS; Wang, QY; Mao, XC; Sheng, SR or concate me.. Formula: C14H10O

I found the field of Polymer Science very interesting. Saw the article Synthesis and characterization of new cardo poly(ether amide)s containing 9(10H)-anthrone units published in 2020. Formula: C14H10O, Reprint Addresses Wang, QY; Sheng, SR (corresponding author), Jiangxi Normal Univ, Minist Educ, Key Lab Funct Small Organ Mol, Nanchang 330022, Jiangxi, Peoples R China.. The CAS is 90-44-8. Through research, I have a further understanding and discovery of Anthrone

A new aromatic diamine, 10,10-bis[4-(4-aminophenoxy)phenyl]-9(10H)-anthrone (BAPA) has been synthesized from anthrone via three-step procedure. Direct phosphorylation polycondensation of BAPA with various aromatic dicarboxylic acids produced a series of cardo poly(ether amide)s with inherent viscosities of 0.97-1.29 dL g(-1). All the polymers were readily soluble in polar solvents such as N-methyl-2-pyrrolidone, N, N-dimethylacetamide (DMAc), and pyridine at room temperature, and afforded transparent, strong, and flexible films upon casting from DMAc solvent. The resulting poly(ether amide)s had glass transition temperatures of 254-316 degrees C, 10% weight loss temperatures of 495-524 degrees C, and char yields of 55-70% at 800 degrees C in nitrogen. These polymers were amorphous and their films exhibited tensile strengths of 81.6-104.7 MPa, tensile moduli of 1.8-2.4 GPa, and elongations at break of 8-15%.

About Anthrone, If you have any questions, you can contact Luo, YS; Wang, QY; Mao, XC; Sheng, SR or concate me.. Formula: C14H10O

Reference:
Thiomorpholine – Wikipedia,
,Thiomorpholine | C4H9NS – PubChem

 

An overview of features, applications of compound:119-61-9

Application In Synthesis of Benzophenone. About Benzophenone, If you have any questions, you can contact Wang, YH; Zhao, JW; Xu, F; Zhang, QD; Ai, ZL; Li, BY or concate me.

Authors Wang, YH; Zhao, JW; Xu, F; Zhang, QD; Ai, ZL; Li, BY in WILEY published article about in [Wang, Yuan-Hui; Ai, Zhi-Lu] Henan Agr Univ, Minist Agr & Rural Affairs Peoples Republ China, Key Lab Staple Grain Proc, Zhengzhou, Peoples R China; [Wang, Yuan-Hui; Zhao, Jing-Wen; Xu, Fei; Li, Bo-Yu] Henan Univ Technol, Coll Food Sci & Technol, Zhengzhou, Peoples R China; [Zhang, Qi-Dong] Zhengzhou Tobacco Res Inst CNTC, Zhengzhou, Peoples R China in 2021.0, Cited 31.0. Application In Synthesis of Benzophenone. The Name is Benzophenone. Through research, I have a further understanding and discovery of 119-61-9

The volatile compounds of Jiaozi-steamed breads (JSBs) fermented by Jiaozi starters from eight regions in China were extracted using simultaneous distillation and extraction (SDE) and headspace solid-phase microextraction and determined using gas chromatography-mass spectrometry (GC-MS). 1-Hexanol, 3-methyl-1-butanol, phenylethyl alcohol, benzaldehyde, naphthalene, ethanol, acetic acid, and n-hexadecanoic acid were the main volatiles of JSBs. Principal component analysis exhibited that the volatiles of JSBs from Nanyang City, Xi’an City, and Zhumadian City was negatively correlated to that of other five JSB samples. Cluster analysis demonstrated that the volatile characteristics of JSBs from Heze City, Minqin County, Taian City, Weinan City, and Yuncheng City belonged to a category, and the JSBs of Nanyang City, Xi’an City, and Zhumadian City were different from other five JSBs. It demonstrated that the volatile components of steamed breads in North China and South China were different. Practical applications From this study, it can be seen that simultaneous distillation and extraction (SDE) can completely extract volatile compositions of steamed breads fermented by Chinese traditional starter Jiaozi. SDE/GC-MS was suitable for the analysis of JSBs volatile composition. The relative contents of 1-hexanol, 3-methyl-1-butanol, phenylethyl alcohol, benzaldehyde, naphthalene, ethanol, acetic acid, and n-hexadecanoic acid in JSBs were at high level, and their contents could be used as a marker to identify JSBs. The volatile compositions of JSBs made of Jiaozi starters from Heze City, Minqin County, Taian City, Weinan City, and Yuncheng City were similar. However, JSBs of Nanyang City, Xi’an City, and Zhumadian City were different from other five JSBs. The volatile components of steamed breads in North China and South China were different, which reflected the difference in dietary habit in the southern and northern areas of China.

Application In Synthesis of Benzophenone. About Benzophenone, If you have any questions, you can contact Wang, YH; Zhao, JW; Xu, F; Zhang, QD; Ai, ZL; Li, BY or concate me.

Reference:
Thiomorpholine – Wikipedia,
,Thiomorpholine | C4H9NS – PubChem

 

Brief introduction of 3-Nitrobenzaldehyde

Product Details of 99-61-6. About 3-Nitrobenzaldehyde, If you have any questions, you can contact Eslahi, H; Sardarian, AR; Esmaeilpour, M or concate me.

In 2021 CHEMISTRYSELECT published article about CRYSTAL-STRUCTURE; DOCKING in [Eslahi, Hassan; Reza Sardarian, Ali] Shiraz Univ, Dept Chem, Coll Sci, Shiraz 7194684795, Iran; [Esmaeilpour, Mohsen] Niroo Res Inst, Chem & Proc Engn Dept, Tehran 1468617151, Iran in 2021, Cited 82. The Name is 3-Nitrobenzaldehyde. Through research, I have a further understanding and discovery of 99-61-6. Product Details of 99-61-6

The novel copper(II) ions decorated Fe3O4@SiO2 composite magnetic spheres were synthesized by grafting copper(II) ions onto glucosamine modified Fe3O4@SiO2 NPs. The magnetic Fe3O4@SiO2-TCT-GA-Cu(II) catalyst were characterized by varies physicochemical techniques such as FT-IR, FE-SEM, TEM, DLS, XRD, EDX, VSM, TGA, VSM, ICP, and UV-Vis. The catalytic performance of this novel catalyst was studied in the green preparation of 5-substituted 1H-tetrazole based hybrids via three-component and one-pot reaction of sodium azide, hydroxylamine hydrochloride, and various aldehydes in water and ethylene glycol, as a green solvent mixture. This green protocol provides significant advantages such as non-vigorous conditions, short reaction times, outstanding yield of desired tetrazoles, minimizing of chemical waste, wide-ranging substrate, quick and efficient work-up procedure and using environmentally benign, durable, cost effective, magnetically separable, reusable nanocatalyst.

Product Details of 99-61-6. About 3-Nitrobenzaldehyde, If you have any questions, you can contact Eslahi, H; Sardarian, AR; Esmaeilpour, M or concate me.

Reference:
Thiomorpholine – Wikipedia,
,Thiomorpholine | C4H9NS – PubChem

 

You Should Know Something about Anthrone

Computed Properties of C14H10O. About Anthrone, If you have any questions, you can contact Bazyar, Z; Hosseini-Sarvari, M or concate me.

In 2019 J ORG CHEM published article about HIGHLY SELECTIVE OXIDATION; BAND-EDGE EMISSION; ONE-POT SYNTHESIS; MERGING PHOTOREDOX; SUPPORTED GOLD; LIGHT; NANOPARTICLES; EFFICIENT; CATALYSIS; DECARBOXYLATION in [Bazyar, Zahra; Hosseini-Sarvari, Mona] Shiraz Univ, Dept Chem, Shiraz 7194684795, Iran in 2019, Cited 88. The Name is Anthrone. Through research, I have a further understanding and discovery of 90-44-8. Computed Properties of C14H10O

Photoredox catalysis in recent years has manifested a powerful branch of science in organic synthesis. Although merging photoredox and metal catalysts has been a widely used method, switchable heterogeneous photoredox catalysis has rarely been considered. Herein, we open a new window to use a switchable heterogeneous photoredox catalyst which could be turned on/off by changing a simple stimulus (O-2) for two opponent reactions, namely, oxidative and protodecarboxylation. Using this strategy, we demonstrate that Au@ZnO core-shell nanoparticles could be used as a switchable photocatalyst which has good catalytic activity to absorb visible light due to the localized surface plasmon resonance effect of gold, can decarboxylate a wide range of aromatic and aliphatic carboxylic acids, have multiple reusability, and are a reasonable candidate for synthesizing both aldehydes/ketones and alkane/arenes in a large-scale set up. Some biologically active molecules are also shown via examples of the direct oxidative and protodecarboxylation which widely provided pharmaceutical agents.

Computed Properties of C14H10O. About Anthrone, If you have any questions, you can contact Bazyar, Z; Hosseini-Sarvari, M or concate me.

Reference:
Thiomorpholine – Wikipedia,
,Thiomorpholine | C4H9NS – PubChem

 

Machine Learning in Chemistry about C13H10O

About Benzophenone, If you have any questions, you can contact Zhang, XY; Wei, DB; Sun, XF; Bai, CZ; Du, YG or concate me.. Recommanded Product: 119-61-9

Recommanded Product: 119-61-9. Zhang, XY; Wei, DB; Sun, XF; Bai, CZ; Du, YG in [Zhang, Xinyi; Wei, Dongbin; Sun, Xuefeng; Bai, Chenzhong; Du, Yuguo] Chinese Acad Sci, Res Ctr Ecoenvironm Sci, State Key Lab Environm Chem & Ecotoxicol, Beijing 100085, Peoples R China; [Zhang, Xinyi; Wei, Dongbin; Sun, Xuefeng; Bai, Chenzhong; Du, Yuguo] Univ Chinese Acad Sci, Beijing 100049, Peoples R China published Free available chlorine initiated Baeyer-Villiger oxidation: A key mechanism for chloroform formation during aqueous chlorination of benzophenone UV filters in 2021, Cited 41. The Name is Benzophenone. Through research, I have a further understanding and discovery of 119-61-9.

Chloroform, a regulated disinfection by-product in water, is often generated during chlorination disinfection treatment. However, the formation of chloroform is heavily dependent on the molecular structures of precursors. Moreover, compounds containing ketone moiety are ubiquitous in water environments. However, it is unclear if they can generate chloroform during chlorination. In this study, 14 benzophenones (BPs), efficient and widely used UV filters, with different substituents were selected to explore chloroform formation during chlorination. All 14 BPs generated chloroform, with yields dependent on their molecular structures and operational conditions. Compounds 2,2′,4,4′-tetrahydroxy-BP and benzophenone produced the highest and lowest chloroform of 0.313 and 0.013 g/g, respectively, corresponding to the fastest and slowest formation rate constants of 1.41 x 10(-1) and 2.71 x 10(-2) min(-1). Alkaline conditions and high chlorine dosages were favorable to chloroform formation. Three reactions played key roles in chloroform formation from BPs: (1) chlorine initiated Baeyer Villiger oxidation converted ketone moieties of BP molecules into esters; (2) the esters further underwent hydrolysis and formed phenolic and benzoic products; and (3) benzoic acids underwent decarboxylation and hydrolysis to form phenolic products. Subsequently, these phenolic products could further generate chloroform in the chlorination system. More importantly, BPs could generate chloroform in the ambient water matrices during practical chlorination treatment. This work emphasized the critical role of Baeyer-Villiger oxidation for chloroform formation, implying that pollutants containing aromatic ketone moieties generate chloroform during chlorination disinfection, and their potential risk should therefore be reviewed. (C) 2020 Elsevier Ltd. All rights reserved.

About Benzophenone, If you have any questions, you can contact Zhang, XY; Wei, DB; Sun, XF; Bai, CZ; Du, YG or concate me.. Recommanded Product: 119-61-9

Reference:
Thiomorpholine – Wikipedia,
,Thiomorpholine | C4H9NS – PubChem