Solvent-free synthesis of benzoic esters and benzyl esters in novel Brønsted acidic ionic liquids under microwave irradiation

Fischer esterifications of benzoic acid with a variety of alcohols and a variety of acids with benzyl alcohol could be promoted by four novel Brønsted acidic ionic liquids a–d that bear a benzyl on the imidazolium or pyridinium cation. The reactions were carried out smoothly without the need of added catalyst with good to excellent isolated yields (77–98.5%) under solvent-free microwave irradiation conditions in the presence of 50 mol% ionic liquids. These ionic liquids could be recovered easily and recycled three times without any significant loss in their catalytic activity.     

Selective Oxidation of Hydrocarbons on Composite Oxides

A catalyst for the selective oxidation of hydrocarbons to unsaturated aldehydes, acids, acid anhydrides, divinyls, or styrenes has to perform several functions. First, it must supply a limited amount of oxygen to the reactant, sufficient to allow the formation of the desired product but not enough to allow complete oxidation. Further, it must provide appropriate sites for the adsorption of the hydrocarbons in deformed, reactive states. Last, the catalyst should be capable of transferring electrons from and to the reactants. These three demanding characteristics of an active catalyst impose severe limitations on the systems that can effectively perform selective oxidation reactions. Therefore catalyst selectivity, normally measured by the rate of formation of the specific product relative to that of undesired products, is sensitive to reaction conditions (temperature, feed rate, feed composition, and reactor design) and is very dependent on the details of the structure of the catalyst itself, its carriers, and promoters.     

基于2,3-吡啶二羧酸阳离子的系列Br(o)nsted酸性离子液体的合成与表征

以2,3-吡啶二羧酸、1-溴丁烷、苄基氯、相应的有机或无机酸为原料,经两步反应,在2,3-吡啶二羧酸阳离子基础上合成了8种结构新颖的室温功能化离子液体,这些功能化离子液体在室温下呈液相,同时表现出较强的Brnsted酸性.     

Effects of Simulated Herbivory on Defensive Compounds in Forage Plants of Norwegian Alpine Rangelands

A field study on the effects of current grazing practices on plants in central Norway found no increase in either phenolic compounds or proteinase inhibitors in plants subjected to grazing by sheep. This could either reflect insufficient damage to the plants due to low grazing intensity or a lack of a long-term response of the plants to grazing. In this study, we tested the hypothesis that damage to forage plants used by sheep and rodents in Norwegian alpine rangelands can stimulate a long-term (at least 2-week) increase in levels of defensive compounds. We used clipping experiments to manipulate the severity and timing of damage to eight species of common plants used by herbivores in Norway. Under greenhouse conditions (i.e., climate-controlled), we subjected mature plants to one of four clipping treatments: control (0% leaf tissue removed), low (10–15% leaf tissue removed), high (70–75% leaf tissue removed), or sustained (15% of leaf tissue removed every other day up to a total removal of 75%, i.e., five clippings over 9 days). Samples were collected 2 weeks after final clipping and analyzed for concentrations of total phenolics, proteinase inhibitors, ratio of total phenolics to soluble proteins, and ratio of proteinase inhibitors to soluble plant proteins. As expected, the different species of plants responded differently to simulated herbivory, but most plants either showed no response to mechanical wounding and tissue loss or had reduced defensive compounds. Thus, our results do not support the hypothesis that herbivory induces a long-term increase in defensive compounds in alpine rangelands of Norway, a result consistent with those from field studies.     

Vector phase correlation

Phase correlation has been applied for over 25 years to applications such as registration of images, but there has never been a simple generalisation to vector images. Here, for the first time, a vector approach to phase correlation, based on hypercomplex Fourier transforms, is proposed and demonstrated     

Instant Ciphertext-Only Cryptanalysis of GSM Encrypted Communication

In this paper we present a very practical ciphertext-only cryptanalysis of GSM (Global System for Mobile communications) encrypted communication, and various active attacks on the GSM protocols. These attacks can even break into GSM networks that use “unbreakable” ciphers. We first describe a ciphertext-only attack on A5/2 that requires a few dozen milliseconds of encrypted off-the-air cellular conversation and finds the correct key in less than a second on a personal computer. We extend this attack to a (more complex) ciphertext-only attack on A5/1. We then describe new (active) attacks on the protocols of networks that use A5/1, A5/3, or even GPRS (General Packet Radio Service). These attacks exploit flaws in the GSM protocols, and they work whenever the mobile phone supports a weak cipher such as A5/2. We emphasize that these attacks are on the protocols, and are thus applicable whenever the cellular phone supports a weak cipher, for example, they are also applicable for attacking A5/3 networks using the cryptanalysis of A5/1. Unlike previous attacks on GSM that require unrealistic information, like long known-plaintext periods, our attacks are very practical and do not require any knowledge of the content of the conversation. Furthermore, we describe how to fortify the attacks to withstand reception errors. As a result, our attacks allow attackers to tap conversations and decrypt them either in real-time, or at any later time. We present several attack scenarios such as call hijacking, altering of data messages and call theft. An earlier version of this paper appears in Barkan et al. (Advances in Cryptology, Proceedings of Crypto 2003, Lecture Notes in Computer Science, vol. 2729, pp. 600–616, 2003).     

Effect of fruit canopy positions on the properties of apricot (Prunus armeniaca L.) varieties

Effect of fruit position in the tree on properties of two commercially important apricot varieties (Hac?halilo?lu and Kabaa??) was investigated. Principal component analysis separated apricots based on their variety and canopy position. Hac?halilo?lu variety was distinguished from Kabaa?? variety by its higher pH, weight, dry matter (DM), soluble solid, citric acid, and catechin content. Major features which contribute to variation of the canopy position were β‐carotene, malic acid, catechin, ascorbic acid, soluble solid content, DM, malic acid, and neochlorogenic acid. Fruits located on the top of the tree were richer in phenolic compounds and exhibited higher degree of antioxidant activity measured by 2.2′‐azinobis[3‐ethylbenzthiazoline‐6‐sulphonic acid] (ABTS) method than those located on the bottom of the tree. Except for chlorogenic and neochlorogenic acids, all other forms of phenolic compounds were higher in concentration in the fruits located on the top of the canopy especially for the Hac?halilo?lu variety.

Practical applications

The results of this study may be of interest for apricot breeders as it provides important information about cultivar specific canopy effect on fruit quality. Furthermore, the results can be used by apricot producers for canopy management and pruning strategies to create of homogenous microclimate in the fruit canopy which would limit quality variation.     

Feasibility of bio-hythane production by co-digesting skim latex serum (SLS) with palm oil mill effluent (POME) through two-phase anaerobic process

Hydrogenogenic batch fermentation without nutrients addition was investigated at different SLS: POME mixing ratios of 100:0, 95:5, 90:10, 85:15, 80:20, 75:25, 70:30, 65:35, 60:40, 55:45,50:50, and 0:100 (Volatile Solid, VS basis) at initial organic concentrations of 21 and 7 g-VS/L. Satisfactory hydrogen yield of 84.5 ± 0.7 mL H₂/g-VS_added was achieved from 7 g-VS/L batch having SLS: POME-VS mixing ratio of 55:45. Adding NaHCO₃ 3 g/L or 0.43 g-NaHCO₃/g-VS) in the two-stage anaerobic system at 7 g-VS/L could provide sufficient buffering capacity. Hydrogenogenic effluent from 7 g-VS/L batch at SLS: POME mixing ratio of 55:45 (VS basis) could further generate rather high methane yield of 311.2 ± 8.0 mL- CH₄/g-VS_added in themethanogenic stage.According to the experimental results, bio-hythane approximately 55.5 × 10⁶ m³/year with 21% (V/V) of hydrogen, equivalent to51.0 × 10⁶ l-gasoline could be produced potentially from 3.88 × 10⁶ m³ of mixed SLS and POME through the two-stage anaerobic co-digestion.