A Novel Approach to Clean Tanning Technology

Traditional chrome tanning technology is still widely used today. In this technology, chrome shaving as well as chrome contained effluent in tanning and retanning processes is a big issue in the industry. Wet white tanning technology has been gaining in importance in recent years, but in general, the comprehensive performance of chrome-free tanned leather is not comparable with that of chrome tanned leather. In the present work, chrome-free tanning and chrome tanning are combined in a reversed procedure, which produces leather with chrome tanned leather quality without chrome tanned leather waste problems. In this procedure, a special amphoteric organic compound, no pickle, no salt chrome-free tanning agent TWT was used to tan delimed hides （no pickle） making wet white with shrinking temperature at 80-85 ~C. Then, new method called reversed tanning further process the wet white into chrome-tanned crust. In this reversed method, retanning, fatliquoring and coloring processes were carried out before chrome tanning. This technology eliminates chrome waste issue in tanning, shaving, post tanning processes. The chrome contained effluent is only concentrated in the last chrome tanning process. The leather made with this technology has complete conventional chrome-tanned leather quality. In this way, chrome leather quality without chrome waste problems was achieved. So, it is a new clean tanning technology.

Mechanism of Chrome-free Tanning with Tetra-hydroxymethyl Phosphonium Chloride

Tetra-hydroxymethyl phosphonium chloride （THPC） has been considered as an important chrome-free tanning agent. To understand the THPC tanning mechanism, the structure, charge distribution, activity and tanning ability of each phosphorous compound in THPC tanning system were studied, by ^31p NMR, FT-IR spectroscopy, differential scanning calorimetry （DSC） and computational chemistry method, etc. When pH raised to 6.0, the decomposition of THPC would take place, which results in a production of free formaldehyde, tri-hydroxymethyl phosphonium （TrHP） and tri-hydroxymethyl phosphine oxide （TrHPO）. At pH 9.0, THPC will be converted completely to TrHP and most TrHP is further oxidized into TrHPO. It is possible that, in reaction of phosphorous compounds and collagens, both P-C and C-O bonds would break simultaneously or individually. From molecular charge distribution and bond polar properties, it is deduced that, if P-C bonds break, the activity is in order of TrHPO 〉 THPC 〉 TrHE whereas if C--O bonds break, the order is TrHP 〉 THPC 〉 TrHPO. It is more possible that P--C bonds will break in reaction with collagen, and TrHPO may be more active in the THPC tanning system. The results of tanning and DSC also prove the above conclusion. Furthermore, the fact that the shrinkage temperature of THPC tanned leather was below 70℃ when basified to pH 5.0 or lower suggests that the hydroxymethyl groups of THPC and TrHP are less possible to combine directly with amino groups of collagen.

Synthesis and study of MPNS/SMA nano-composite tanning agent

The radical polymerization of maleic anhydride（MA）,styrene（ST）with the vinyl groups introduced onto the surface of the nano-sized silica via solution polymerization method was developed.The methacryloxypropyl nano-sized silica（MPNS）was used as macromonomer and polymerized with maleic anhydride and styrene by initiating with BPO in toluene.The structure and properties of MPNS/SMA nano-composite were characterized by FT-IR spectra and TEM.Meanwhile,it was applied as tanning agent compared with the traditional styrene-maleic anhydride copolymer in leather.It was found that the applied leather had better quality characteristics with the addition of the nano-sized silica.

Diatomaceous silica filter aid filtration for the effective separation of colloidal Cr（OH）＿3 precipitate from tanning wastewater

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Eco-friendly Leather： Chromium Reduction in the Tanning Cycle

The leather manufacturing is traditionally responsible for high environmental pollution. Tannery effluent contains, indeed, large amounts of lime sludge, sulfides, acids, toxic metals salts, in particular chromium salts, which are toxic, non-biodegradable and hardly disposable. For this reason, great research efforts are addressed to establish a significantly eco-sustainable and convenient business for companies and to produce high quality leather products. The replacement of current commercial chemical and toxic products with innovative natural/naturalized products and technologies in some crucial phases of the tanning cycle （mainly bating and defatting）, can induce an eco-friendly reduction of the needed chromium amount. Leather samples, treated with innovative bating and defatting products and tanned by several different Cr contents, were characterized by SEM-EDS （Scanning Electron Microscopy equipped with Energy Dispersive X-Ray Spectroscopy） and TGA （Thermogravimetric Analysis）. SEM-EDS was used to observe the surface and cross-section morphology and to provide a semi-quantitative elemental analysis, while TGA to evaluate the thermal stability and decomposition phases. The compatibility of the innovative products was demonstrated and the environmental impact of the process, performed by the effluents characterization, was effectively improved as a result of a 20% Cr lowering. The use of innovative products and the chromium reduction did not affect the thermal stability, leather morphology and not involve significant differences in the composition.

Indoor tanning bed use and risk of food addiction based on the modified Yale Food Addiction Scale

The popularity of indoor tanning may be partly attributed to the addictive characteristics of tanning for some individuals.We aimed to determine the association between frequent indoor tanning,which we view as a sunogate for tanning addiction,and food addiction.A total of 67,910 women were included from the Nurses＇ Health Study II.In2005,we collected information on indoor tanning during high school/college and age 25-35 years,and calculated the average use of indoor tanning during these periods.Food addiction was defined as ≥3 clinically significant symptoms plus clinically significant impairment or distress,assessed in 2009 using a modified version of the Yale Food Addiction Scale.Totally 23.3%（15,822） of the participants reported indoor tanning at high school/college or age 25-35 years.A total of 5,557（8.2%） women met the criteria for food addiction.We observed a dose-response relationship between frequency of indoor tanning and the likelihood of food addiction（P_（trend）〈 0.0001）,independent of depression,BMI,and other confounders.Compared with never indoor tanners,the odds ratio（95%confidence interval） of food addiction was 1.07（0.99-1.17） for average indoor tanning 1-2 times/year,1.25（1.09-1.43） for 3-5times/year,1.34（1.14-1.56） for 6-11 times/year,1.61（1.35-1.91） for 12-23 times/year,and 2.98（1.95-4.57） for 24 or more times/year.Frequent indoor tanning before or at early adulthood is associated with prevalence of food addiction at middle age.Our data support the addictive property of frequent indoor tanning,which may guide intervention strategies to curb indoor tanning and prevent skin cancer.

Tanning Industry in Xinji City

Xinji City, in the middle south of Hebei Province, has a tanning history of more than 400 years. The city boasted over 100 kinds of fur and leather products, over 300 workshops and shops and 24 foreign agencies in the early years of the Qing Dynasty (1644-1911). Since 1949, especially since 1981,the city’s tanning industry has witnessed a big leap. There are around 10, 000 tanning enterprises in the city with an annual industrial value of RMB 1.3 billion and an annual export value of US $

慢性手部湿疹患者口服补骨脂素联合家用便携式tanning unit进行PUVA治疗与医院监管下的PU-VA治疗的比较:一种公开随机对照实验的有效性

Objective: To study whether oral psoralen-UV-A (PUVA) with a portable tanning unit at home is as effective as hospital-administered bath PUVA in patients with chronic hand eczema. Design: Open-label randomized controlled trial, with a 10week treatment period and an 8-week follow-up period. Setting: Two university hospital dermatology departments in the Netherlands, specializinginhand eczema. Patients: One hundred fifty-eight patients with moderate to severe chronic hand eczema (more than 1 year induration). Interventions: Oral PUVA using methoxsalen capsules and a simple portable commercial facial tanning unit, or hospital-administered bath PUVA with trioxsalen. Main Outcome Measures: The primary outcome was clinical assessment by a hand eczema score (evaluation of desquamation, erythema, vesiculation, infiltration, fissures, itch, and pain, each on a 4-point scale) after 10 weeks of treatment. The secondary outcome was hand eczema score at 8 weeks of follow-up, after completion of treatment. The tertiary outcome was travel cost and time off work. Results: Both groups showed a comparable and substantial decrease in hand eczema score (meaningful clinical improvement). This decrease was maintained during the follow-up period. Patients treated with oral PUVA at home had lower travel costs and less time off work. Conclusions: Oral PUVA at home has a clinically relevant efficacy, similar to that of hospital-administered bath PUVA. This effect was maintained during an 8-week follow-up period. It resulted in lower travel costs and less time off work.

A High Throughput Screening Platform for Skin Tuning Properties from Natural Products: Identification of Skin Tanning Compounds

Skin lightening and tanning are two major areas dominating the market of skincare and cosmetic products. Though the demands are originated from two different communities, the two areas share a same goal—skin colour tuning. The known safe compounds with skin colour tuning activities are limited. In contrary, Chinese medicinal herb provides a pool of natural bioactive compounds, which have been used in Asian countries for long time and have been tested for its toxicity. Here, we demonstrate a high throughput screening platform for potential compounds usable for skin colour tuning. From 147 natural compounds, 26 of them showed potential in skin tanning functions by using the high throughput melanogenesis platform based on the melanogenesis assay on B16 melanocytes. Five of them promoted melanogenesis by over 50%. Moreover, apart from 1, 8-dihydroxyanthraquinone, the other four compounds showed enhancement effect on tyrosinase activity. From the result, the compounds increased the Vmax of tyrosinase without changing the Km in a dose-dependent manner. Thus, there should be no irreversible structural change of the enzyme. Definitely, this report contributes to the development of personalization in skincare and cosmetic products.

Egg tanning improves the efficiency of CRISPR/Cas9-mediated mutant locust production by enhancing defense ability after microinjection

The mutant efficiency and hatching ratio are two key factors that significantly affect the construction of genome-modified mutant insects.In the construction of CRISPR/Cas9-mediated dsLmRNase2^(–/–)mutant locusts,we found that the tanned eggs which experienced a 20-min contact with the oocyst exhibited a higher success rate compared to fresh newly-laid eggs that were less tanned.However,the heritable efficiency of the dsLmRNase2 deletion to the next generation G_(1 )progeny was similar between adults derived from the tanned or less tanned engineered eggs.Further,the similar effective mutant ratios in the normally developed eggs and G_(0) adults of tanned and less tanned eggs also indicated that tanning did not reduce the absolute mutation efficiency induced by CRISPR/Cas9.Moreover,we found that the syncytial division period,which was longer than the time for tanning,conferred a window period for microinjection treatment with efficient mutation in both tanned and less tanned eggs.We further found that tanned eggs exhibited a higher hatching rate due to a reduced infection rate following microinjection.Both the anti-pressure and ultrastructure analyses indicated that the tanned eggs contained compressed eggshells to withstand increased external pressure.In summary,tanned eggs possess stronger defense responses and higher efficiency of genome editing,providing an improved model for developing Cas9-mediated gene editing procedures in locusts.

Tanning capacityof Tessmannia burttii extracts:thepotentialeco-friendlytanning agents fortheleatherindustry

In the present study,the tannins from stem and root barks of Tessmannia burttii Harms(Caesalpiniaceae),a plant species abundantly growing in Tanzania and other parts of Africa,were investigated for their suitability in hides tanning.Tannin powder was extracted at selected temperatures(30,50 and 80°C)and the influence of each temperature on the crosslinking capacity was evaluated.The interaction mechanism between hide powder collagen and the tannins was studied by Differential Scanning Calorimetry(DSC),trinitrobenzensulfonic(TNBS)acid assay and amino acid hydrolysis methods.Extraction temperatures showed low influence on crosslinking capacity of the tannins.However,extract obtained at 50°C exhibited best performance in terms of gap size between T onset and T peak.The stem bark extract yield was higher than that from the root bark,but both were within the recommended ranges.The tannin content(61%)of T.burttii stem bark extract was above recommended value(10%),whereas its total phenolic content and total flavonoic content were found to be above that of commercial Acacia mearnsii tannin.The study of cross-linking parameters as a function of pH showed cross-linking to occur via a covalent mechanism at the basic amino groups.However,the bonds were not resistant to acid hydrolysis.The observed interaction mechanism indicated that tannins from stem and root barks of T.burttii belong to the condensed tannin,similar to A.mearnsii(black wattle),a commercial tannin source that was used in this study as a reference.Findings from this study depict that T.burttii extracts are auspicious eco-friendly alternative source of vegetable tannins to overcome the use of chromium salts in the leather industry.

Interaction between retanning agents and wet white tanned by a novel bimetal complex tanning agent

A promising and practical chrome-free tanning system has been developed based on a novel Al–Zr bimetal complex tanning agent.However,to achieve satisfactory resultant leather,the retanning process that is compatible with this emerging tannage needs to be investigated systematically.This paper aims to explore the interaction between the bimetal complex tanned wet white and retanning agents.The isoelectric point(pI)of wet white was 7.2,which was nearly the same as wet blue.The electropositivity of wet white was even higher than that of wet blue during post-tanning processes,resulting in higher uptake rate of retanning agents.The distribution of various retanning agents in wet white was analyzed by pI measurement of layered leather and fluorescent tracing technique.The retanning agents were unevenly distributed throughout the cross-section,which might be an important restriction factor in obtaining satisfactory organoleptic properties of the crust leather.This fact is mainly due to the strong electrostatic interaction between anionic retanning agents and wet white.Applying a high dosage of multiple retanning agents in a proper sequence of addition benefited the full penetration of retanning agents in leather matrix and thus improved the organoleptic properties of crust leather.This work provides guidance for optimizing retanning process of the wet white leather.

Influence of microwave on chromium complex composition in tanning liquor

Since microwave irradiation could promote hydrolysis and olation of chromium tanning liquor,but the influence of microwave on chromium complex component in the liquor was still unknown.Chromium sulphate solution(0%basicity)and 33%basicity chromium tanning liquor were subjected microwave(MW)and water bath(WB)heating,and the samples without any warming were regarded as control.Ion exchange chromatography(IEC)and gel filtration chromatography(GFC)were used to measure the charge composition and molecular size of chromium complexes in each sample.FT-IR was used to characterize the structure of chromium complexes in each composition separated by IEC.Moreover,the chromium tanning liquor after warming was used in hide powder tanning trials to illustrate whether microwave would affect its tanning ability.The results show there are more high positive charge and large molecular size complexes in chromium tanning liquor after warming but the phenomena are more significant in MW samples compared with WB due to non-thermal effect of microwave.In addition,microwave has more powerful effect on 33%basicity chromium tanning liquor hydrolysis and olation to generate larger molecular size complexes.In FT-IR results,the combination pattern between chromium and ligands are changed after warming but there is no difference between WB and MW.The chromium exhaustion and thermal stability of hide powder tanned with chromium tanning liquor after microwave irradiation are both higher.It could conclude that both thermal and non-thermal effects of microwave promote the process together,and the nonthermal effect leads to more high positive charge and large molecular size complexes and has stronger influence on high polarity system.In short,this work would provide theoretical basis for applying microwave in tanning agent modification and chrome tanning process further.

Collagen structure changes during chrome tanning in propylene carbonate

Green solvents,such as propylene carbonate(PC),can be used in leather processing to improve the efficiency of chrome tanning and reduce wastewater.Here we report a combined small-angle X-ray scattering(SAXS)and differential scanning calorimetry(DSC)study on PC and its efficacy as a carrier medium during chrome tanning.SAXS analysis on the collagen structure of chrome tanned leather using PC,compared to conventionally tanned leather using water,showed an increase in Cr uptake in addition to the more uniform penetration of Cr through the leather cross-section.The increased binding of Cr to the collagen matrix drives the decreased hydration environment of the collagen triple helix.Furthermore,DSC studies show a uniform hydrothermal stability for the PC samples due to the more even distribution of Cr through the collagen matrix.Understanding the mechanisms by which chrome tanning occurs in non-aqueous solvents can guide us towards a more sustainable future for the leather industry.

Aluminum tanning of hide powder and skin pieces under microwave irradiation

The application and mechanism study of microwave irradiation in traditional industries have attracted considerable attention owing to the unique thermal and athermal effects that could lead to unexpected benefits in high-efficiency and clean production.Herein,we report the investigation of the aluminum tanning under microwave irradiation upon using hide powder and skin pieces,respectively,as simulants of real hide or skin.The aluminum tanning process and the tanned products under microwave heating(MWH)were studied and compared with those of conventional water bath heating(WBH)as the controls.For the tanning system of hide powder,the tanning effluents were analyzed in terms of pH,conductivity,dielectric constant and aluminum content,and the tanned powder was investigated by differential scanning calorimetry(DSC),thermogravimetric(TG)analysis,and FT-IR spectroscopy.For the skin piece system,the pH and aluminum content of tanning effluents were also determined,and at the same time,DSC,TG,SEM,FT-IR and shrinkage temperature were used to illustrate the actions of microwaves on the structure and properties of the tanned pieces.The results show that aluminum reactivity in the penetration and binding process of collagen fibers in hide powder and skin pieces improved using microwave treatment.The residual aluminum content was greatly reduced by microwave heating action,and the increased amount of aluminum with evener distribution was observed in the tanned products.Microwave irradiation also resulted in the tanned products with better thermal stability and thermal decomposition resistance.This work further promotes application of microwave treatments for aluminumbased tanning in leather industry.

Alternative splicing of POUM2 regulates embryonic cuticular formation and tanning in Bombyx mori

Insect cuticle is an apical extracellular matrix produced by the epidermis,tracheal,hind-and foregut epithelia during embryogenesis and renewed during molting and metamorphosis.However,the underlying regulatory mechanism for embryonic cuticle formation remains largely unclear.Here,we investigate the function of the transcription factor POUM2 in the embryonic cuticular formation in Bombyx mori,a model lepidopteran insect.Clustered regularly interspaced palindromic repeats(CRISPR)/CRISPR-associated protein-9-mediated knockout of POUM2 resulted in the defect of cuticular deposition,pigmentation,and sclerotization in the embryos.Differentially expressed transcripts analysis of 7-d-old embryos identified 174 up-or downregulated cuticular protein transcripts,8 upregulated chitin degradation transcripts,2 downregulated chitin synthesis transcripts and 48 up-or downregulated transcription factor transcripts in the POUM2−/−embryos.The expression levels of the key factors of the tyrosine metabolic pathway,such as tyrosine hydroxylase(Th),Dopa decarboxylase(DDC),and arylalkylamine N-acetyltransferase(aaNAT),were significantly decreased in the POUM2−/−embryos.POUM2 isoform POUM2-L specifically bound the POU cis-regulatory element(CRE)in the Th promoter and increased the transcription of Th,whereas POUM2-S could not bind the POU CRE,although it also increased the transcription of Th.Heterogeneous nuclear ribonucleoprotein Squid-1 directly bound the POUM2 pre-mRNA(messenger RNA)and inhibited the alternative splicing of POUM2-L to POUM2-S mRNA.These results suggest that POUM2 participates in the cuticular formation by regulating the chitin and cuticular protein synthesis and metabolism,and the cuticular pigmentation and sclerotization by regulating tyrosine metabolism during embryogenesis.This study provides new insights into novel function of POUM2 in embryogenesis.

Extraction of a novel tanning agent from indigenous plant bark and its application in leather processing

The use of vegetable tanning materials in leather processing has drawn attention as an alternative to basic chromium sulphate for its natural abundance and environmental aspects.In this work,an attempt has been made to extract vegetable tannins from Xylocarpus granatum bark using different solvents(e.g.,water,methanol,ethanol,and chloroform)and compare with conventional vegetable tanning agents such as mimosa and quebracho.The highest extraction efficiency was observed 31.22%by methanol.The presence of tannin content and polyphenolic compounds,e.g.(-)epicatechin(503 mg/100 g dry extract),catechin hydrate(218 mg/100 g dry extract),catechol(29 mg/100 g dry extract)were ensured by UV-Vis,FT-IR spectroscopy and HPLC.Again,condensed tannins,moisture content,and pH of the methanol extracted tannin were found 47.80%,5.82%,and 3.97 respectively.The leather tanned by Xylocarpus granatum tannin showed a shrinkage temperature of 86.34±1.52℃.Other properties such as tensile strength,tear strength,grain cracking load,and distention at grain cracking were comparable to conventional vegetable-tanned leather.The cross-sectional morphology of the tanned leathers was also characterized by scanning electron microscopy(SEM)which revealed a compact structure of the leather fibers.In light of the findings from the study,X.granatum bark tannin could be a well alternative to chromium and a new source of vegetable tannin for the leather industry.

Combination tanning mechanism inspired environmentally benign catalyst for efficient degradation of tetracycline

The utilization of chelation reaction between metals and tannins is a common tanning method in leather chemistry.Herein,a novel combination tanning mechanism inspired environmentally benign catalyst(CMBT-Fe^(0))was synthesized by immobilizing Fe nanoparticles onto bayberry tannin(BT)grafted chitosan microfibers(CM).The obtained catalyst featured a well-defined microfibrous structure,on which Fe^(0)nanoparticles were highly dispersed to exhibit exceptional catalytic activity for the degradation of tetracycline(TC).The catalytic activity of CMBT-Fe^(0)was 1.72 times higher than that of the commercial Fe^(0)nanoparticles without immobilization,with 95.03%of TC degraded within 90.0 min.The CMBT-Fe^(0)catalysts were recycled 6 times,with the removal rate of TC maintained at 82.56%.Furthermore,a possible mechanism responsible for the catalytic removal of TC was provided by analyzing the catalytic degradation products via liquid chromatography-mass spectrometry.Therefore,our investigation successfully developed efficient catalysts to address the concerned environmental issue of antibiotic pollution.

Extraction of a novel tanning agent from indigenous plant bark and its application in leather processing

The use of vegetable tanning materials in leather processing has drawn attention as an alternative to basic chromium sulphate for its natural abundance and environmental aspects. In this work, an attempt has been made to extract veg-etable tannins from Xylocarpus granatum bark using different solvents (e.g., water, methanol, ethanol, and chloroform) and compare with conventional vegetable tanning agents such as mimosa and quebracho. The highest extraction efficiency was observed 31.22% by methanol. The presence of tannin content and polyphenolic compounds, e.g. (-)epicatechin (503 mg/100 g dry extract), catechin hydrate (218 mg/100 g dry extract), catechol (29 mg/100 g dry extract) were ensured by UV-Vis, FT-IR spectroscopy and HPLC. Again, condensed tannins, moisture content, and pH of the methanol extracted tannin were found 47.80%, 5.82%, and 3.97 respectively. The leather tanned by Xylocar-pus granatum tannin showed a shrinkage temperature of 86.34 ± 1.52 °C. Other properties such as tensile strength, tear strength, grain cracking load, and distention at grain cracking were comparable to conventional vegetable- tanned leather. The cross-sectional morphology of the tanned leathers was also characterized by scanning electron microscopy (SEM) which revealed a compact structure of the leather fibers. In light of the findings from the study, X. granatum bark tannin could be a well alternative to chromium and a new source of vegetable tannin for the leather industry.

磁控溅射制备铝、钛掺杂钽氮化合物薄膜的微观结构与电学性能研究

采用反应射频磁控溅射法,在Al_(2)O_(3)陶瓷基片上通过共溅射的方式成功制备了Al-TaN和Ti-TaN薄膜,并通过调节Al和Ti靶的溅射功率以实现了掺杂,研究了掺杂元素变化对薄膜微观结构和电学性能的影响。结果显示,随着掺杂元素Al和Ti的增加,TaN薄膜的粗糙度逐渐增大,晶体结构逐渐向非晶转变;Al元素掺杂时,当Al靶掺杂功率由0 W升至70 W,薄膜电阻率由0.88 mΩ·cm增至82.72 mΩ·cm;Ti元素掺杂时,当Ti靶掺杂功率由0 W升至70 W,电阻率由1.03 mΩ·cm降至0.32 mΩ·cm。此时,随着Al和Ti靶材掺杂功率由0 W升至70 W,薄膜的TCR值分别从-1313×10^(-6)℃^(-1)逐渐负偏至-3831×10^(-6)℃^(-1)和从-1322×10^(-6)℃^(-1)正偏至-404×10^(-6)℃^(-1)。该研究为溅射制备掺杂TaN薄膜提供了深刻的理论和实验基础。