An explanation of the discrepancy between the results of h.p.l.c. and DNS assays in the analysis of lignocellulosic hydrolysates

The concentration of polymerised sugars in enzymic hydrolysates from lignocellulosic materials was determined by high pressure liquid chromatography (h.p.l.c.) of hydrolysates before and after dilute acid hydrolysis: significant quantities of polymerised glucose and xylose were found in lignocellulosic hydrolysates, and these accounted for the discrepancy between the dinitrosalicyclic acid (DNS) and h.p.l.c. assay methods.     

An h.p.l.e. and m.s. analysis of distillate fractions of neutral oil from hydrogenated Akabira coal to elucidate chemical structures

Akabira coal-derived neutral oil was separated into 25 narrow boiling range fractions covering 183–423 °C, and subsequently separated into compound class fractions : alkanes, monoaromatics, naphthalene-type diaromatics, fluorene-type diaromatics and tri- and/or tetraaromatics, by high performance liquid chromatography (h.p.l.c.). The compound type analyses of the distillate/h.p.l.c. fractions were performed using electron impact mass spectroscopy (e.i.m.s.) or field ionization mass spectroscopy (f.i.m.s.). Aromatic/hydroaromatic compound types and the alkyl side-chain carbon distribution of the distillate/h.p.l.c. fractions were clarified, based on the separation behaviour of h.p.l.c. and the type analyses according to Z value by m.s. By the distillation/h.p.l.c./m.s. method, coal-derived oil was characterized in terms of the distribution of the numbers of aromatic rings, naphthenic rings and carbons of alkyl groups attached to these rings. The variations in chemical structure in a compound class with distillation temperature are discussed in terms of these chemical structural factors.     

The use of the F.p.l.c.R system in method development and process monitoring for industrial protein chromatography

The f.p.l.c.^R for high performance biomolecular purification is now widely used in laboratory and pilot scale separations, both as a means of developing new methods for purification and for analysing the purity of intermediary and final products. The speed of the technique means that it is possible to analyse fractions from a process step and to receive the results within 15–30 min. Two aspects are examined in this paper: the monitoring of protein product formation during fermentation and the analysis of fractions in large scale chromatography. The suitability of the technique in an operating process is discussed.     

Compositions of distillate recycle solvents derived from direct coal liquefaction in the SRC-I process: 1. Hydrocarbons

The qualitative and quantitative compositions of 260–427 °C distillate recycle solvents derived from direct liquefaction of subbituminous Wyodak coal and bituminous Kentucky $\text{9}\text{14}$ coal in the SRC-I process are discussed. A liquid chromatography method which involves a column switching technique was used to provide solubility characteristics and compound-class compositions. The hydrocarbon compounds, which accountfor> 60 wt% of the distillate recycle solvents, were further analysed using a unique combination of high-performance liquid chromatography (h.p.l.c.) and field ionization mass spectrometry (f.i.m.s.). Thirty homologous series were identified. Carbon number and distribution and concentration of the homologous series were determined. The h.p.l.c./f.i.m.s. method unravelled various hydroaromatic types which otherwise would be very difficult or impossible to determine.     

Comparison of coal tars by l.c.-m.s.

The application of l.c.-m.s., using both quadrupole and magnetic sector mass spectrometers, to the analysis of aromatic fractions of hydropyrolysis tars and a Gray-King tar, is described. The results are compared with those obtained by g.c.-m.s. and probe mass spectrometric methods such as field desorption, desorption chemical ionization and low ionizing voltage probe. The molecular weight range observed by l.c.-m.s. is much greater than that observed by g.c.-m.s. and is similar to those observed by probe methods. The proportion of the aromatic fractions eluted from the NH₂-bonded silica column by hexane is not known, but some polar molecules are retained and can be eluted by increasing solvent polarity. The results indicate the presence of extensive homologous series of aliphatics and aromatics with carbon numbers exceeding C₅₀. The extent of alkylation decreases with increasing severity of the method used to prepare the tar.     

Characterisation of separated melamine—formaldehyde adducts (methylolmelamines) and adduct mixtures by h.p.l.c. and by n.m.r. and u.v. spectroscopy

Most of the individual methylolmelamines that occur in melamine–formaldehyde adduct mixtures have been separated by preparative high-performance liquid chromatography (h.p.l.c.) and recovered in amounts sufficient to allow their characterisation by high-field ¹H- and ¹³C-n.m.r. Particular attention has been paid to the chemical shifts of the aromatic azine carbons of the melamine nuclei. These carbon shifts are shown broadly to be in agreement with some values previously published, but additional assignments have been made. It is shown that a satisfactory quantitative analysis of the methylolmelamines in a melamine–formaldehyde adduct mixture can be carried out either by h.p.l.c. or by ¹³C-n.m.r.     

Separation and characterization of large-ring number polycyclic aromatic hydrocarbons in non-distillable, pyridine soluble coal-liquids

Low-pressure liquid chromatography, high-performance liquid chromatography, and field ionization mass spectrometry (f.i.m.s.) were used to obtain compositional information on large-ring number polycyclic aromatic hydrocarbon (PAH) present in a non-distillable coal liquid sample. A highly selective h.p.l.c. method for the separation of (PAH) from polar compounds was applied to nitrogen-compound fractions derived from a Wyodak non-distillable ( > 427 °C) coal-liquid sample. F.i.m.s. analyses revealed that the PAH subfractions isolated by the h.p.l.c. procedure contained large-ring number PAH and relatively few nitrogen compounds. The methods developed can generally be applied to the analyses of complex organic mixtures, and in conjunction with other methods, can yield detailed polycyclic aromatic hydrocarbon compositional information.     

Garment dyeing

Rapid and reliable procedures for the chemical analysis of insect-resist agents, or mothproofers, on wool have been developed. These methods, based on chromatographic analysis(using g.l.c. and h.p.l.c), are routinely employed by many laboratories for the quality control of insect-resist agents on wool textile products. Full details of the procedures used to determine the traditional agents, recognised by the International Wool Secretariat, are described in the paper.     

A g.l.c. simulated distillation technique to study changes in the composition of coke-oven road tars in service

A simulated distillation technique has been developed making use of gas-liquid chromatography (g.l.c.) for the quantification of oils present in road tars derived from coke-oven crude tars. The tar-oil constituents are grouped into boiling temperature ranges which coincide with those of fractions or cuts used in a standard (conventional) distillation test. The g.l.c. method caters for the wide range in boiling temperatures of tar-oil constituents and for the fact that only about half of the tar substance injected is eluted from the column. In the analyses of tars recovered from road surfaces a means has been found to compensate for the presence of detritus in the tar. This method has several important advantages over the standard distillation procedure. Its accuracy and precision are superior and it can be used to determine constituents boiling as high as 400°C (673 K). (Due to the thermal sensitivity of coal tar hydrocarbons, the temperature in the standard distillation test may not exceed 340°C.) The g.l.c. method is more rapid and the small amount of tar required facilitates the analyses of tars weathered in road surfaces. In addition, repeat analyses can be carried out without inconvenience and the handling of the tar material is reduced. The g.l.c. method provides a powerful research tool for the study of the weathering of road tars. This paper gives the results of some weathering investigations. These show that even constituents with high boiling points (in the range 370–400°C) may be partially lost from tars in the first year of service. Oil losses are most rapid in the first year, but all constituents with boiling points below 300°C may be lost after prolonged service. From data provided by this method and measurements of the change in viscosity of tars on weathering, it has been possible to conclude that, in the case of coke-oven tars, evaporation is the major weathering mechanism in the South African Highveld climate. There is a good correlation between oil losses and the hardening of tars, particularly in the early life of a spray-and-chip surfacing. Such studies have led to the development of improved road tar binders with economic benefit to the South African road industry.     

H.p.l.c. quantitation of hydrocarbon class types in cracked products

H.p.l.c. was optimized to obtain quantitative compositional data on hydrocarbon class type (saturates, olefins, aromatics plus polars) in cracked products from vacuum gas oil (370–500°C) feed over REY zeolite catalyst in a micro-activity test unit. H.p.l.c. separation was achieved using an amino column, a backflush device and nC₆ as mobile phase. An RI detector was used to obtain total saturates and aromatics and a 200 nm u.v. detector to estimate olefins and aromatic hydrocarbons by ring number. Quantitation was achieved using external standard procedure and standards were prepared from the identical petroleum products to obtain response factors. A considerable variation in the liquid product yield during cracking reactions was noticed, from 40 to 70 wt%. Cracking reactions were also favoured through hydrogen transfer, increasing substantially the aromatic content in the range 50–70 wt%. Olefins were also formed during cracking, ranging from 5 to 10 wt%.     

The role of vinylsulphonyl reactive dyes in prevention of wool damage

Reactive dyes of the vinylsulphone and α-bromoacrylamido types inhibit wool fibre degradation during dyeing. The effect is proportional to the amount of dye applied, which may be explained in terms of set inhibition and modification of the cell membrane complex. Reactive dyes are capable of interfering with the fibre thiol-disulphide interchange reactions, as evidenced by a study of model thiol derivatives of vinylsulphone dyes. H.p.l.c. has been widely employed to separate and assist with identification of these thiol adducts. The role of the cell membrane complex has been clarified using reactive vinylsulphone fluorescent compounds as dye models and following fibre penetration using fluorescence microscopy.     

Synthesis of Isocryptolepine-Triazole Adducts and Evaluation of Their Cytotoxic Activity

Eighteen hybrid compounds between 8-bromo-2-fluoro-isocryptolepine ( 4 ) and 1,2,3-triazole were synthesized via azide rearrangement-annulation reaction. Compound 4 underwent regioselective N-propargylation and click reaction to form 8-bromo-2-fluoro-isocryptolepine-triazole hybrids 11 which were evaluated for cytotoxic activity. Compound 11 c containing 1-anisyltriazole was the most effective in inhibiting HepG2, HuCCA-1 and A549 cell lines (IC₅₀ values of 1.65–3.07 μM) while compounds 11 a (1-phenyltriazole), 11 j (1-para-CF₃-benzyltriazole) and 11 l (1-meta-Cl-benzyltriazole) were potent inhibitors of HuCCA-1, HepG2 and A549 cell lines, respectively. Moreover, 11 l showed the lowest cytotoxicity to normal human kidney cell line. Compounds 11 c and 11 l provided improvement of cytotoxic activity over 4 . Compounds 4 , 11 c and 11 l were selected to investigate their mechanisms of action. The results showed that 4 could induce G2/M cell cycle arrest and was involved in the upregulation of p53 and p21 proteins. However, the mechanisms of growth inhibition by 11 c and 11 l were associated with G0/G1 cell cycle arrest and mediated by induction of oxidative stress.     

Characterisation of some melamine-formaldehyde condensates and some cured resins by 1H, 13C and 15N n.m.r. spectroscopy

Some oligomeric species (condensates) in a melamine-formaldehyde adduct mixture have been isolated by preparative high performance liquid chromatography (h.p.l.c.) and partly identified by high field ¹H and ¹³C nuclear magnetic resonance (n.m.r.) spectroscopy. The oligomers are shown most likely to be largely dimers, trimers and tetramers and to contain both methylene and methylene ether linkages. Some cured melamine-formaldehyde resins are shown by solid-state cross-polarisation magic angle sample spinning (c.p./m.a.s.) ¹³C and ¹⁵N n.m.r. to contain linear and branched methylene and methylene ether linkages but few free methylol groups. The relative proportions of the various linkages in both the oligomers and the cured resins appear to be controlled mainly by the melamine: formaldehyde ratio.     

Upgrading of coal-derived liquids: 3. Characterization of upgraded liquids by thin-layer chromatography combined with flame-ionization detection

Four components, namely, saturates, aromatics, resins and asphaltenes, in upgraded coal-derived liquids were determined by thin-layer chromatography combined with flame-ionization detection (t.l.c./FID method). The results agree with previous results using various analytical methods. The t.l.c./FID method was found to be a simple and effective method for screening of hydroconversion catalysts and also for a follow-up investigation of the chemical changes of coal-derived liquids during the hydroconversion process.     

Comparison of molecular weight distribution models for polymers characterized by g.p.c.

A semi-empirical model which employs polynomials based on general free radical polymerization kinetics, is developed to describe the molecular weight distribution data as well as to evaluate the average molecular weights of a variety of commercial thermoplastics including polystyrene, poly(methyl methacrylate) and low density polyethylene. These novel expressions are equally applicable to a natural rubber sample with a bimodal distribution. Least-squares methods for the classical Schulz and Flory distribution functions are introduced to handle the g.p.c. data of the above polymers. Comparison of the results collected from various analyses indicates clearly that the polynomial model is the most versatile one in the sense that it can be utilized to smooth out satisfactorily the molecular weight distribution data of many polymers. In general, the Wesslau distribution function is particularly good for the highly branched polyolefin and the Schulz model is fairly effective for the addition polymers of moderately sharp molecular weight distribution, presumably with $\text{M}\text{?}{}_{\mathrm{<mtext>w</mtext>}}\text{M}\text{?}{}_{\mathrm{<mtext>n</mtext>}}\text{=3.0}$. However, the Flory and Tung distributions are found to be rather inferior in the present studies. On the basis of the current findings, a new procedure is suggested to facilitate the computations of the true average molecular weights from g.p.c. data directly.     

Methods of Attenuating Ischemia-Reperfusion Injury in Liver Transplantation for Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is one of the most frequent indications for liver transplantation. However, the transplantation is ultimately associated with the occurrence of ischemia-reperfusion injury (IRI). It affects not only the function of the graft but also significantly worsens the oncological results. Various methods have been used so far to manage IRI. These include the non-invasive approach (pharmacotherapy) and more advanced options encompassing various types of liver conditioning and machine perfusion. Strategies aimed at shortening ischemic times and better organ allocation pathways are still under development as well. This article presents the mechanisms responsible for IRI, its impact on treatment outcomes, and strategies to mitigate it. An extensive review of the relevant literature using MEDLINE (PubMed) and Scopus databases until September 2020 was conducted. Only full-text articles written in English were included. The following search terms were used: “ischemia reperfusion injury”, “liver transplantation”, “hepatocellular carcinoma”, “preconditioning”, “machine perfusion”.     

Comparative evaluation of the Double-Cantilever Beam and Tapered Double-Cantilever Beam tests for estimation of the tensile fracture toughness of adhesive joints

The continuous development observed in bonded joints, along with the improvements of the adhesives’ properties, are resulting in an increase of the bonded joint applications, as well as the variety of applications. Regarding the strength prediction of adhesive joints, two highly relevant methods are Fracture Mechanics and Cohesive Zone Models (CZM). By Fracture Mechanics, this is usually carried out by an energetic analysis. CZM enable the simulation of damage initiation and propagation. The tensile critical strain energy release rate (G_Ic) of adhesives is one of the most important parameters for predicting the joint strength. Two of the most commonly used tests are the Double-Cantilever Beam (DCB) and the Tapered Double-Cantilever Beam (TDCB). This work aims to assess the capability of the DCB and TDCB test to estimate the value of G_Ic of adhesive joints. Three types of adhesives with different levels of ductility are used, to study the accuracy of the typical data reduction methods under conditions that are not always consistent with Linear Elastic Fracture Mechanics (LEFM) principles. For both test protocols, methods that do not require measurement of the crack length (a) during the test are evaluated. In the DCB test, these are the Compliance Calibration Method (CCM), Corrected Beam Theory (CBT) and Compliance-Based Beam Method (CBBM). The methods used in the TDCB test are the Simple Beam Theory (SBT), CCM and CBT. With few exceptions, the results were consistent between the different methods considered for each test. The discrepancy of results is higher when comparing the two types of tests, except for the brittle adhesive. It was concluded that the data reduction methods for the TDCB test are too conservative to measure G_Ic of ductile adhesives.     

Four Novel p.N385K,p.V36A,c.1033–1034insT and c.1417–1418delCT Mutations in the Sphingomyelin Phosphodiesterase 1 (SMPD1) Gene in Patients with Types A and B Niemann-Pick Disease (NPD)

Background: Types A and B Niemann-Pick disease (NPD) are autosomal-recessive lysosomal storage disorders caused by the deficient activity of acid sphingomyelinase due to mutations in the sphingomyelin phosphodiesterase 1 (SMPD1) gene. Methods: In order to determine the prevalence and distribution of SMPD1 gene mutations, the genomic DNA of 15 unrelated Iranian patients with types A and B NPD was examined using PCR, DNA sequencing and bioinformatics analysis. Results: Of 8 patients with the p.G508R mutation, 5 patients were homozygous, while the other 3 were heterozygous. One patient was heterozygous for both the p.N385K and p.G508R mutations. Another patient was heterozygous for both the p.A487V and p.G508R mutations. Two patients (one homozygous and one heterozygous) showed the p.V36A mutation. One patient was homozygous for the c.1033–1034insT mutation. One patient was homozygous for the c.573delT mutation, and 1 patient was homozygous for the c.1417–1418delCT mutation. Additionally, bioinformatics analysis indicated that two new p.V36A and p.N385K mutations decreased the acid sphingomyelinase (ASM) protein stability, which might be evidence to suggest the pathogenicity of these mutations. Conclusion: with detection of these new mutations, the genotypic spectrum of types A and B NPD is extended, facilitating the definition of disease-related mutations. However, more research is essential to confirm the pathogenic effect of these mutations.     

Coal flash pyrolysis: 2. Polymethylene compounds in low temperature flash pyrolysis tars

Pyrolysis of coals at low temperatures (< 600 °C) produces tars containing the precursors of the low molecular weight aliphatic hydrocarbons, such as ethylene and propylene, observed on flash pyrolysis of the coals at higher temperatures (700–800 °C). This is shown by further pyrolysis of these low temperature tars at high temperatures. Various methods, including isolation by h.p.l.c. were used to confirm the presence of straight chain paraffin and olefin pairs (C₁₄C₂₆ and above) in the low temperature tars. Pyrolysis of pure paraffins and olefins in this molecular weight range at temperatures > 700 °C produce ethylene, propylene and other cracking products similar to those obtained on flash pyrolysis of coal.     

Continuous Dyeing

The review concentrates on the period 1973-79 and is restricted to fully-continuous methods, i.e. semi-continuous processes such as pad-batch or pad-roll are not considered. An indication of the major trends of development during this period is given. The most important section relates the form in which the substrate is dyed to the type of equipment used: topics include the continuous dyeing of (a) undrawn synthetic filaments in the gel state, (b) warp yams, (c) conventional woven and knitted fabrics, (d) carpets. Developments in low pick-up techniques of application, such as foam-padding, loop-transfer and spray methods, as well as in fixation and washing processes, are discussed. A much shorter section on non-aqueous methods follows. me large number of patents referring to continuous dyeing from organic solvents and dating mainly from early in the period covered by the review are mentioned briefly. The more promising recent development of the combined dyeing and mercerizing of cotton in liquid ammonia is given attention. The third section is concerned mainly with developments in dyes, auxiliaries and process sequences in continuous dyeing. Unlike the earlier sections, it is subdivided according to the major fibre types: wool and nylon, cellulosic fibres, polyester-cellulosic blends. The concluding paragraphs reiterate the major themes, with an attempt to indicate possible future trends in continuous dyeing.